ruin BEN'GURION UNIVERSITY OF THE NEGEV SIXTH ISRAEL MATERIALS ENGINEERING CONFERENCE IMEC VI
PROGRAM AND ABSTRACTS
THE DEAD SEA, ISRAEL FEBRUARY 24-25 1993 j; s
i XJJ1 BENGUHION UNIVERSITY OF THE NEGEV SIXTH ISRAEL MATERIALS ENGINEERING CONFERENCE IMEC VI
PROGRAM AND ABSTRACTS
THE DEAD SEA, ISRAEL FEBRUARY 24-25 1993 TABLE OF CONTENTS Page #
Organizing Committee
Conference Sponsors I
Scientific Program 1 - 18
Authors Index 19 - 22
Abstracts
'-Plenary Sessions A-l - C-2
"-Technical Sessions 1.1.1 - 4.4.5
•-Posters PI.3 - P2.53 ORGANIZING COMMITTEE
D. Eliezer, Ben Gurion University of the Negev (Chairman) D. Itzhak, Ben Gurion University of the Negev E. Abramov, Nuclear Research Center, Negev M. Fass, Israel Defence Force A. Grinbaum, Bromine Compounds Ltd. J. Haddad, Ben Gurion University of the Negev N. Nir, Armament Development Authority H. Rahman, Technion, Israel Institute of Technology A. Siegman, Technion, Israel Institute of Technology M. Talianker, Ben Gurion University of the Negev M. Wolf, National Council for Research and Development Y. Zchavi, Technion, Israel Institute of Technology
CONFERENCE SPONSORS;
* Ben Gurion University of the Negev
* Technion, Israel Institute of Technology
* Israel Atomic Energy Commission
* Armament Development Authority
* Ministry of Science and Technology
* Ministry of Energy
* Carmel Bank
* Landseas (Israel) Ltd.
* Buehler UK, Ltd.
CONFERENCE ORGANIZERS ORTRA LTD. 2 Kaufman Street P.O. Box 50432 Tel Aviv 61500, Israel Tel: 972-3-664825, Fax: 972-3-660952
-I- SCIENTIFIC PROGRAM WEDNESDAY. FEBRUARY 24. 1993
10:00-10:30 OPENING SESSION Green Hall Chairmen: D. Ellezer, Ben Gurion University A. Siegman, Technion
OPENING REMARKS D. EUezer, Chairman, Organizing Committee A. Braverman, President, Ben Gurion University of the Negev
10:30-11:20 PLENARY SESSION A Green Hall Chairmen: D. Eliezer, Ben Gurion University A. Siegman, Technion
A-l STRUCTURAL MATERIALS FOR NASP T.M.F. Ronald, Wright-Patterson Air Force Base, USA
A-2 MICROSTRUCTURE, PHASE TRANSFORMATIONS AND MECHANICAL PROPERTIES OF ORDERED ORTHORHOMBIC Ti NbAl-BASED ALLOYS R.G. Rowe, GE Corporate Research and Development, USA
11:20-11:40 Coffee Break Foyer
11:40-12:45 PLENARY SESSION B Green Hall Chairmen: D. Itzhak, Ben Gurion University I. Gefen, Ministry of Defense
B-l POLAR LANGMUIR BLODGET FILMS FOR NONLINEAR OPTICS AND PYROELECTRIC DEVICES • J.B. Lando, CWR
B-2 SYNTHESIS AND PROPERTIES OF TRI-ALUMINIDES BY MECHANICAL ALLOYING • R.B. Schwarz, Los Alamos National Lab., USA
B-3 ATOMISTIC SIMULATION OF HYDROGEN-INDUCED FRACTURE OF AN IRON-BASED SUPERALLOY N.R. Moody, S.M. FoUes, J.E. Angelo, M.I. Baskes, Sandia National Laboratories, USA
* Abstract not submitted
-1- f WEDNESDAY. FEBRUARY 24. 1993 /Continued
12:45-13:15 I POSTER SESSION PI Sufat Hamidhar Pl.l DEVELOPMENT OF COMPOSITE COATINGS BY PLASMA SPRAY * M. Konrad, Ben Gurion University, G. Gurevitz, Israel Aircraft Industries
PI.2 PROCESS OF STABLE AUSTENITE PRODUCTION DURING THE POINT WELDING OF MARAGING STEELS • A. Pasternak, Y. Neiman, T. Wagner, Israel Military Industries
PI .3 PROPERTIES OF CEMENTED CARBIDE WITH DIFFERENT CoCONTENT AND DIFFERENT GRAINS SIZE OF TUNGSTEN CARBIDE FOR CONSTANT MEAN FREE PATH R. Porat, I. Gavisb, Iscar
P1.4 ASSESSMENT OF FATIGUE LIFE OF ALUMINUM ALLOY COMPONENTS WITH CRACKS USING RANDOM LOAD MONITORING SYSTEM R. Arone, S. Ustilovsky, G. Sharshukov, A. Loksb, L. Potepun, Technion
P1.5 SOURCES OF ACOUSTIC EMISSION IN AL-LI BASE ALLOYS AND THEIR VARIATIONS WITH HEAT TREATMENT V. Zeides, I. Roman, The Hebrew University
PI .6 SELF-STRENGTHENING OF THE STAINLESS-STEEL UNDER SHOCK LOADING E. Zaretsky, Ben Gurion University of the Nsgev
P1.7 DISLOCATION SOURCES IN SHOCK DEFORMATION OF METALS E. Zaretsky, Ben Gurion University of the Negev
P1.8 LOCAL REINFORCEMENT OF METAL CASTINGS WITH CERAMIC FIBRES/ PARTICLES B. Barkai, N. Kami, Technion
P1.9 FORMATION OF Co AND Ta SILICIDES ON Si (100) and Si (111) SUBSTRATES FROM CODEPOSITED Co AND Ta FILMS S. Darwish, J. Pelleg, Ben Gurion University of the Negev
P1.10 PROBABILISTIC PROCESSES AND FORMING STRUCTURE DURING SOLIDIFICATION D. Kopeliovicu, Antek, Ltd.
Pl.H THERMAL TREATMENT AND BRAZING IN VACUUM AND HIGH VACUUM FURNACES • I. Goldfarb, Chromat Ltd.
P1.12 INFLUENCE OF GRAIN BOUNDARY SEGREGATION ON THE THERMOPHYSICAL PROPERTIES OF CERAMICS T. Gambaryan, E.Y. LUovsky, M. Shapiro, Technion
P1.13 TEMPERATURE AND GAS PRESSURE DEPENDENCES OF THERMAL CONDUCTIVITY OF DENSE AND INSULATING CERAMIC MATERIALS E. Y. Litovsky, M. Shapiro, Technion
* Abstract nut submitted I WEDNESDAY. FEBRUARY 24. 1993 /Continued
POSTER SESSION Pi/Continued
P1.14 SYNTHESIS OF IRON, NICKEL AND COBALT TITANIDES FROM FINE ELEMENTAL POWDERS E. Paransky, I. Gotmao, E.Y. GutmaDUS, Technion
P1.15 DEVELOPMENT AND CHARACTERIZATIONS OF COMPOSITE SOLID ELECTROLYTE FOR BIPOLAR LITHIUM BATTERIES FOR ELECTRIC VEHICLES E. Peled, D. Golodnitsky, Tel Aviv University
P1.16 CAPACITORS WITH GRAIN BOUNDARY BARRIER LAYER MICROSTRUCTURE IN THE BaO-(SrO)-TiO AND BaO-SnO -TiO SYSTEMS V. Stancovski, M. Kravcnik, A. Goldstein, A. Bar, Technion
P1.17 EFFECT OF HEAT TREATMENT CONDITIONS IN ALUMINUM-MATRIX COMPOSITES C. Alexandra, P. Moldovan, Polytechnic Institute Bucharest, G.V. Ghica, INTEC, Romania
P1.18 IN SITU QUALITY MONITORING TECHNIQUE FOR A HIP PROCESS O. Tevet, Ben Gurion University, O. Yeheskel, U. Atzmony, M.P. Dariel, NRC
P1.19 MICROSTRUCTURAL EVALUATION OF CAST ALUMINUM ALLOY MATRIX COMPOSITES P. Moldovan, C. Alexandra, Polytechnic Institute Bucharest, G.V. Ghica, INTEC, Romania
P1.20 UNUSUAL MECHANICAL PROPERTIES OF HIGH-STRENGTH ROLLED STEEL WITH MACROANISOTROPIC STRUCTURE P.D. Odessky, S.I. Morozov, M.R. Uritsky, A.B. Steblov, V.T. Cheraenko, TsNIISK, Russia
P1.21 MAGNETOCHEMISTRY OF THE TETRAHALOFERRATE (III) IONS IN THE A3Fe2X9 SERIES R. Suaviv, IMI, R.L. Carlin, The University of Illinois, USA
P1.22 STRUCTURE AND PROPERTIES OF RAPIDLY SOLIDIFIED GOLD-TITANIUM ALLOYS T. Abuud, D. Shechtman, Technion
P1.23 MICROSTRUCTURAL AND COMPOSITIONAL CHARACTERIZATION OF TiW/Al-0.8% SI/TiW/PtSi/(100)Si A. Ashkenazi, Y. Komem, Technion I. Lerner, National Semiconductor
P1.24 UTILIZING ACOUSTIC-EMISSION AS A NON-DESTRUCTIVE METHOD FOR PRESSURE VESSELS A. Mittelman, The Hebrew University
P1.25 Au-Cu-Cd ELECTROPLATED ALLOYS STRUCTURE AND MECHANICAL PROPERTIES S. LJbov, E. Igner, Jotaly Ltd.
P1.26 PROCESSING OF A HIGH-PURITY ALUMINA MATERIAL O. Glozman, L. Baum, W.D. Kaplan, D.G. Brandon, Technion
-3- WEDNESDAY. FEBRUARY 24. 1993 /Continued
Poster Session Pi/Continued
P1.27 THERMOMECHANICALLY STRENGTHENED SHAPES FOR BUILDING STRUCTURES MADE OF LOW-CARBON AND LOW-ALLOYED STEEL A. Klyucli, Technion
P1.28 PERFORMANCES AND WEAR PHENOMENA OF THE TiN-COATED TWIST DRILLS D. Julean, L. Kerekes, M. Carean, Technical Unveristy of Cluj, Romania
P1.29 SOLID STATE AMORPHIZATION OF Cu-Ti-B POWDER SYSTEM BY MECHANICAL ALLOYING M. Savransky, S. Berger, BX. Weiss, Technion
P1.30 STUDY OF CHEMICAL VAPOR INFILTRATION PROCESS FOR SiC MATRIX COMPOSITES N. Nawi, D. Itzhak, U. Admon, M.S. Dariel, NRCN, Ben Gurion University of the Negev
P1.31 HIGH TEMPERTURE PERICLASE INSULATION 1. Yaniv, R. Cytermann, T. Litovsky, IMI
PI .32 INTERNAL RESIDUAL STRESSES AND WEAR RESISTANCE PROPERTIES OF COMPOSITE NiCr ELECTROCHEMICAL DEPOSITS S. Eskin, O. Berkh, J. Zabavi, J. Lanfir, L, Zevin, Technion
P3.33 QUANTITATIVE NON-DESTRUCTIVE LAYER-BY-LAYER ANALYSIS OF THE SURFACE SUB-REGION OF SOLIDS BY EPMA A. Berner, Technion
P1.34 EDS AND X-RAY DIFFRACTION STUDY OF TERNARY ARTIFICIAL SUPERLATTICES I. Goldfarb, E. Zolotoyabko, A. Berner, D. Shechtman, Technion
Pl.3.5 PREADHESION LASER SURFACE TREATMENT OF COMPOSITE POLYMER, POLYMERS AND METALS ADHERENDS M. Hotel, J. Zahavi, Technion, A, Bucbman, H. Doduik, Rafael
PI .36 LASER PLANARIZATION S. Tamir, J. Zahavi, Technion, Y. Lerner, National Semiconductor
P1.37 DURABILITY OF GLASS FIBRE REINFORCED CEMENT1TIOUS COMPOSITES WITH DIFFERENT LOW ALKALI/LOW LIME MATRICES A. Bentur, K. Kovler, Technion, I. Odler, Technical University Clausthal, Germany
P1.38 CORROSION AND STRESS CORROSION CRACKING BEHAVIOR OF AIS1 304 AND AISI 316 STAINLESS STEELS IN 55% LiBr O. Elias, I. Lev, D. Itzhak, Ben Gurion University of the Negev P. Peled, Bromine Compounds Ltd.
P1.39 THE INFLUENCE OF ELECTRON IRRADIATION ON ADHESION OF METAL FILMS • S. Stolyarova, Eltam Technology Inc.
P1.40 THE EFFECT OF FREQUENCY IN PLASMA MATERIALS PROCESSING A. Raveb, NRC, A. Bettelbeim, J.E. Klemberjj-Sapieha, L. Martinu, M.R. Wertheimer, Ecole Polytechnique, Montreal, Canada
-4- WEDNESDAY. FEBRUARY 24. 1993 /Continued
Poster Session Pi/Continued P1.41 THE POSSIBLE USE OF MIXED IONIC ELECTRONIC CONDUCTORS, INSTEAD OF ELECTROLYTES, IN FUEL CELLS I. Riess, Technion
P1.42 FRACTURE OF CARBON FIBRE REINFORCED PEEK UNDER STATIC AND FATIGUE CONDITIONS: THE INFLUENCE OF THE DEGREE OF CRYSTALLINITY A. Tregub, H. Hare), G. Marom, The Hebrew University C. Migliaresi, University of Trento, Italy
P1.43 RAPID THERMAL ANNEALING OF HIGH DOSE ARSENIC-IMPLANED SILICON E.N. Shauly, National Semiconductor, Technion, ¥. Komem, Technion
P1.44 CHARACTERIZATION OF THE IMPLANT ENERGY DISTRIBUTION OF HIGH CURRENT BF2 IMPLANTS INTO (001) Si N. Bacharach, Technion, E.N. Shauly, National Semiconductor, Technion, Y. Komem, Technion, Y. Avrahamov, National Seminconductor
P1.45 A COMPARISON OF TCA (TRICHLOROATHANE) AND DCE (TRANS 1,2 DICHLOROETHLENE) - GROWN OXIDES ON SILICON E.N. Shauly, National Semiconductor, Technion, R. Mor, Y. Avrahamov, Technion
PJ.46 INVESTIGATION OF THE ACOUSTIC FIELD GENERATED BY REACTIVE SPUTTERED ZnO LAYERS IN ACOUSTO-OPTIC DEVICES, BY MEANS OF X-RAY DIFFRACTION E. Jacobsohn, E. Zolotoyabko, D. Shechtman, Technion
P1.47 IN SITU X-RAY DIFFRACTION DURING THE FORMATION OF TiSi2 C49 FROM Ti-Si MULTILAYER ON Si(lOO) J. Sariel, Nuclear Research Center, H. Chen, University of Illinois, USA
P1.48 PREDICTION AND CALCULATION OF THE PROPERTIES OF CERAMICS WITH SPINAL STRUCTURE E.N. Men, I. Sinitsky, D.G. Brandon, Technion
P1.49 THE SYNERGISTIC EFFECT OF ENVIRONMENTAL PARAMETERS ON THE BEHAVIOR OF PLASTIC MATERIAL R. Huberman, E. Gutman, D. Itzhak, Ben Gurion University of the Negev
P1.50 THE EFFECTS OF DOPANTS ON THE DEVELOPMENT OF THE MICROSTRUCTURE IN THIN FILMS OF Al O W.D. Kaplan, D.G. Brandon, Technion
P1.51 MICROSTRUCTURAL EVALUATION OF ALIGNED CERAMIC MATRIX COMPOSITES N. Shafry, D.G. Brandon, Technion
P1.52 A COMPUTER PROGRAM FOR THE CALCULATION OF ATOMIC POSITIONS ON GENERAL GRAIN BOUNDARIES W.D. Kaplan, D.G. Brandon, Technion
P1.53 STRONG ELECTROSORPTION AT THE THIN BISMUTH FILM/ELECTROLYTE INTERFACE A. Bluvstein, Advanced Technologies Center
P1.54 EVOLUTION OF EQUILIBRIUM THIN CRACK CAUSED BY DIFFUSION IN HIGH STRENGTH MATERIAL AND CERAMICS » V. Strelcov, Israel
13:15-14:20 Lunch Break * Abstract not submitted -5- WEDNESDAY. FEBRUARY 24. 1993 /Continued
14:30-16:00 Kesem Hall SESSION 1.1 - POLYMERS Chairmen: E. Gutman, Ben Gurion University A. Cohen, Rafael
1.1.1 POLYMERIC ANTIPLASTICIZATION POLYCARBONATE WITH POLYCARPROLACTONE M. Sinister, M. Narkis, A. Siegman, Technion
1.1.2 DIELECTRIC AND DYNAMIC MECHANICAL CURE MONITORING OF POLYESTER RESIN: MOLECULAR INTERPRETATION D. Alpersteio, A. Siegman, M. Narkis, Technion
1.1.3 THERMOELASTICITY OF FIBER/MATRIX INTERFACIAL INTER- ACTION IN POLYMER COMPOSITE MATERIALS A. Tregub, G. Marom, Hebrew University V.P. Privalko, Academy of Science of Ukraine, H.G. Kilian, University of Ulm, Germany
1.1.4 DEGRADATION OF POLYMERS BY HYPERTHERMAL ATOMIC OXYGEN R. Vered, G. Nahor, G.D. Lempert, NRCN G. Marom, Hebrew University, L. Lifsbitz, NRC
14:30-16:00 SESSION 1.2 - COMPOSITE MATERIALS I Jerusalem Hall Chairmen: Z. Berger, LAI O. Yeheskel, NRCN
1.2.1 TRANSCRUSTALLINITY IN THERMOPLASTIC COMPOSITES AND ITS INFLUENCE ON THEIR MECHANICAL PERFORMANCE N. Klein, G. Marom, Hebrew University of Jerusalem
1.2.2 POLYETHYLENE FIBRES - POLYETHYLENE MATRIX COMPOSITES: PREPARATION AND PHYSICAL PROPERTIES A. Teishev, Hebrew University of Jerusalem, S. lncardona, The University of Trento, Italy, G. Marom, Hebrew University of Jerusalem
1.2.3 STRUCTURE CHARACTERIZATION OF LASER PROCESSED WC/Co LAYERS M. Boas, Rafael, M. Bamberger, Technion
1.2.4 MICROSTRUCTURE AND MECHANICAL PROPERTIES OF SiC PLATELET / CORDIERITE GLASS-CERAMIC COMPOSITES R. Chaim, Technion
1.2.5 SURFACE ENGINEERING OF STEELS IN MOLTEN BORAX S. B. Fazluddio, A. Koursaris, University of Wilwalersrand, .C. Ringas, MATTEK, SCIR, K. Cowie Melal Technology Engineering, South Africa
-6- WEDNESDAY. FEBRUARY 24. 1993 /continued
14:30-16:00 SESSION 1.3 - MATERIAL PROCESSING 1 Green Hall Chairmen: G. Cohen, NRCN A. Levin, Technion
1.3.1 ELECTRICAL RESISTIVITY OF 3104 Al-ALLOYS A. Stern, NRCN, L. Phillips, A.H. Cahn National Institute of Standards and Technology, USA
1.3.2 DEPOSITION OF DIAMOND FILMS ON CEMENTED CARBIDES (WC + Co) A.K. Mehlmann, A. Fajer, S.F. Dirnfeld, Y. Avigal, Technion R. Porath, Iscar Ltd.
1.3.3 SOLID STATE SYNTHESIS OF CoAl AND NiAl INTERMETALLICS VIA HIGH PRESSURE CONSOLIDATION OF FINE ELEMENTAL POWDERS L. Farber, E.Y. Gutmanas, Technion
1.3.4 THERMODYNAMIC CONSIDERATION FOR SOLID STATE AMORPHIZATION BY MECHANICAL ALLOYING Y. Chakks, S. Berger, B.Z. Weiss, Technion
1.3.5 FACTORS AFFECTING THE QUALITY OF ELECTRON BEAM (EB) WELDS OF Al 1050 END CAPS TO Al 6061 TUBES A. Stern, NRCN and Ben Gurion Univeristy of the Negev, I. Dahan, NRCN, D. Eliezer, Ben Gurion University of the Negev
14:30-16:00 SESSION 1.4 THIN FILMS I Disco Chairmen: M. Dariel, NRCN D. Fuks, Ben Gurion University
1.4.1 HOMOGENIZATION OF LAYERED THIN FILMS UNDER ELECTRIC CURRENT L. Klinger, A. Katsman, A. Levin, Technion
1.4.2 MAGNETRON-SPUTTERED Co-DEPOSITED THIN FILMS AS A METHOD FOR CONSTRUCTION OF MULTI-COMPONENT PHASE SYSTEMS I. Goldfarb, D. Shechtman, Technion
1.4.3 ELASTIC INTERACTION BETWEEN PRECIPITATES IN THIN LAYERS R. Shneck, M.P. Dariel, Ben Gurion University of the Negev, A. Brofcman, Jerusalem
1.4.4 GRAIN GROWTH IN COPPER-CHROMIUM MULTILAYERS U. Admon, NRCN, M.P. Dariel, NRCN, Ben Gurion Univeristy, G. Kimmel, J. Sariel, NRCN, A. Stecnman, NRCN, Ben Gurion University, > L. Zevin, Ben Gurion University
1.4.5 ELECTROMIGRATION IN THIN FILMS: TIME DEPENDENCE OF STRESS DISTRIBUTION AND HILLOCK GROWTH A. Katsman, L. Klinger, A. Levin, E. Glickman, Tcchnion
16:00-16:20 Coffee Break Foyer
-7- WEDNESDAY. FEBRUARY 24. 1993 /continued
16:20-17:50 SESSION 2.1 - CERAMICS Jerusalem Hall Chairmen: R. Chaim, Technion E. Manor, Ben Gurion University
2.1.1 CERAMIX MATRIX COMPOSITES PRODUCED BY DIRECT MELT OXIDATION E. Manor*, Ben Gurion University of the Negev, H. Ni, C.G. Levi, University of California, Santa Barbara, USA R. Mebrabian, Carnegie Mellon University, USA
2.1.2 TENSILE BEHAVIOR OF ALUMINA CARBON/EPOXY LAMINATED SYSTEM D. Sherman, FA Lecki, University of California, Santa Barbara, USA
2.1.3 PROCESSING OF Al O -SiC POWDER "NANOCOMPOSITES" I. Levin, D.G. Brandon, Technion
2.1.4 GLASS-CERAMICS: OPTIMIZATION OF STRUCTURE, PROPERTIES AND TECHNOLOGY R. Khodakovskaya, IMI
16:20-17:50 SESSION 2.2 ENVIRONMENTAL Green Hall EFFECT I Chairmen: Y. Yahalom, Technion M. Talianker, Ben Gurion University
2.2.1 MICROSTRUCTURAL AUDITING TO TRACEABLE STANDARDS IN THE PC DRIVEN QUALITY CONTROL LABORATORY B. Bousfield, Buehler Europe Ltd., UK
2.2.2 THE EFFECT OF TRAPPING AND RELEASE PROCESS ON THERMONUCLEAR FUSION REACTORS PERFORMANCE E. Abramov, Ben Gurion University of the Negev, NRCN
2.2.3 INTERFACIAL EFFECTS IN THE PRESENCE OF HYDROGEN IN Al/Al3Ti/SiC G. Solovioff, D. Eliezer, Ben Gurion University of the Negev
2.2.4 A NEW MATHEMATICAL APPROACH BASED ON THE CIRCULAR DIAPHRAGM TO EXPLAIN THE BLISTER EFFECT ON IMPLANTED METALS D. Moreno, E. Abramov, NCRN, D. Eliezer, Ben Gurion University of the Negev
2.2.5 HYDROGEN EFFECT IN INTERMETALLIC TITANIUM-ALUMINIDES ALLOYS J. Haddad, D. Eliezer, Ben Gurion University of the Negev
! • J WEDNESDAY. FEBRUARY 24. 1993 /Continued
16:20-17:50 SESSION 2.3 - COATINGS I Kesem Hall Chairmen: A. Kaufman, IKA Industrial Consult. Z. Livne, NRCN
2.3.1 EXTREMELY SMALL CRYSTALS IN MULTILAYERED C.V.D. COATING OF TiC + TiN AND THEIR EFFECT ON THE PERFORMANCE OF CUTriNG TOOLS R. Porat, N. Arisbkevich, A, Geltz, Iscar Ltd.
2.3.2 ELECTROCHEMICAL DEPOSITION OF ALLOYS OF GRADUATE COMPOSITION Fe/Cu R. Interto', Y. Yahalom, Technion
2.3.3 THE INFLUENCE OF A THIRD ELEMENT ON THE INTERFACE REACTIONS IN METAL MATRIX COMPOSITES (MMC): Al-GRAPHITE SYSTEM D. Lotker, J. Pelleg, D. Fuks, Ben Gurion University of the Negev, M. Ganor, O. Yeheskel, NRCN
2.3.4 DIAMOND-LIKE CARBON FILMS: PREPARATION, MICROSTRUCTURE- PROPERTY RELATIONSHIP A. Raveh, NRCN, L. Martinu, J.E. Klemberg-Sapieha, MR. Wertheimer, Ecole Polytechnique, Montreal, Canada
16:20-17:50 SESSION 2.4 - ELECTRONIC MATERIALS Disco Chairmen: J. Pelleg, Ben Gurion University N. Croitoru, Tel Aviv University
2.4.1 ELECTRONIC PACKING AND THERMAL DESIGN * C. Colin, AT&T Bell Laboratories, USA
2.4.2 PATTERNING OF SUPERCONDUCTING YBCO FILMS M. Riabkina-Fisbman, J. Zahavi, Technion
2.4.3 AMORPHOUS DIAMOND-LIKE-CARBON FOR MIS AND MIM DIODES M. Alaluf, D. Aizenman, N. Croitoru, Tel Aviv University
2.4.4 BARIUM NONATITANATE DIELECTRC MINIATURE RESONATORS FOR MICROWAVE CIRCUITS A. Goldstein, M. Kravchik, V. Stancovsky, V. Belov, Technion
2.4.5 CORRELATION BETWEEN ELECTRICAL PROPERTIES AND STRUCTURAL CHANGES IN Sb IMPLANTED S^ Ge LAYERS Z. Atzmon, M. Eizenberg, Technion, *}.W? Mayer, Y. Shachara-Diamand, Cornell University, USA, F. Schaffler, Daimler-Benz AG, Germany
* Abstract not submitted
-9- THURSDAY. FEBRUARY 25. 1993
09:00-10:10 PLENARY SESSION C Green Hall Chairmen: S. Dirafeld, Technion A. Stem, NRCN
C-l OXIDATION BEHAVIOUR OF INTERMETA1LIC PHASES FOR HIGH TEMPERATURE APPLICATION HJ. Grabke, M. Steihorst, M.W. Bnimm, Max Planck Institute, Dusscldorf, Germany
C-2 ELECTROMAGNETIC MONITORING OF METAL PROCESSING A.H. Kahn, L.C. Phillips, National Institute of Standards and Technology, USA, A. Stern, NRCN
C-3 MECHANICAL ALLOYING AS A PROCESSING ROUTE FOR Ni-Al BASED INTERMETALLICS * M. Dollar, Institute of Technology, Illinois, USA
10:10-10:30 Coffee Break Foyer
10:30-11:15 Sufat Hamidbar POSTER SESSION P2
P2.1 A METHOD FOR THE MEASUREMENT OF THE THERMAL CONDUCTIVITY TENSOR IN THIN LAYERS OF YBa2Cu O? L. Kornblit, N. Gluzman, M. Auslander, Ben Gurion University of the Negev
P2.2 STRUCTURE OF TiN NITROGEN RICH FILMS R.R. Manory, RMIT, Australia, G. KimmeL NRC
P2.3 BEHAVIOR OF ALUMINUM BRASS • P. Yoffe, Y. Barucb, Israel Electric Corp., S. Libov, Technion
P2.4 XRD INVESTIGATION OF CHROMIUM ALLOYED MEDIUM CARBON STEEL X-20 CrMoV12.1 M. Velin, P. Yoffe, Israel Electric Corp., S. Libov, Technion
P2.5 HYDROGEN CONDITION IN MIDDLE CARBON LOW ALLOY BAINITE STEEL: LOCALIZATION, DIFFUSION AND FLAKES GENERATION IN LARGE FORGING P. Yoffe, Israel Electric Corp.
P2.6 STEEL AND IRON CAST RESISTANT AGAINST WEAR: OPTIMIZATION OF RESISTANCE IN WEAR * I. Gilad, IAI
P2.7 A NEW METHOD FOR DETERMINATION OF HEAT TRANSFER COEFFICIENTS IN THE PROCESS OF RAPID QUENCHING OF AMORPHOUS METALLIC RIBBONS V. Manov, M. Geller, E. Broyk-Levinson, Technion A. Manucbin, Urals Polylechnical Institute, Russia
'Abstract not submitted THURSDAY. FEBRUARY 25. 1993 /Continued Poster Session P2/Continued
P2.8 PECULIARITIES OF GLASS-FORMING CONDITIONS OF INORGANIC, CHALCOGENIDIC AND METALLIC GLASSES V. Manov, D. Shechtman, Technion
P2.9 HYDROGEN ATTACK ON COPPER AND COPPER-BERYLLIUM ALLOY SURFACE D, Moreno, NRC, D. Eliezer, Ben Gurion University of the Negev
P2.10 DECAGONAL QUASICRYSTALLINE PHASE IN THE Al-Cu-Co ALLOY SYSTEM B. Gmshko, R. Wittmann, K. Urban, Forschungszentrum Julich GmbH, Germany
P2.ll SPRAY PROCESSING OF METAL MATRIX COMPOSITES EJ. Lavernia, University of California, USA
P2.12 SOME PRINCIPLES OF CREATION OF PROTECTION STRUCTURES L.I. Slepyan, Tel Aviv University
P2.13 IRRADIATION EFFECT ON THE PROPERTIES OF Cu-0.8% Cr ALLOY: POSSIBILITY OF THE SLIGHTLY DOPED Cu-ALLOYS USE AS CANDIDATE MATERIAL FOR THERMONUCLEAR REACTOR DIVERTER PLATES V.M. Ustinovshchikov, INFODISK Temed Ltd. L.N. Bystrov, N.R. Bochvar, Academy of Science, Russia
P2.14 CYCLIC IRRADIATION EFFECT ON CREEP BEHAVIOR OF Fe-BASE BCC ALLOYS, MODEL ALLOYS L.N. Bystrov, A.B. Tsepelev, Academy of Science, Russia V.M. Ustinovshchikov, INFODISK Temed Ltd.
P2.15 REPLICATION MICROSCOPY AND A REMNANT LIFE ASSESSMENT TECHNIQUE B. Feldraan, Y. Man, A. Kaufman, IKA Industrial Consulting
P2.16 INFLUENCE OF THE FORM OF STRESS-STRAIN DIAGRAM ON THE SHOCK RESISTANCE OF MATERIAL AND STRUCTURES L, Slepyan, Tel Aviv University, M. Ayxenberg-Stepanenko, Negev Advanced Technical Center
P2.17 ENVIRONMENTAL EFFECTS ON THE BEHAVIOR OF CARBON/EPOXY COMPOSITE Y. Bainer, A. Grinberg, LAI, E. Gutman, Ben Gurion University of the Negev
P2.18 ON THE STRUCTURE PERFECTION OF YTTRIUM ALUMINUM GARNET REAL CRYSTALS Y. Rosenberg, I. Keldman, Tel Aviv University
P2.19 EFFECT OF SHORT TIME EXPOSURE TO HIGH TEMPERATURE ON THE TENSILE STRENGTH OF AA 2024 - T8 ALUMINUM SHEETS S. Bar Ziv, A. Cohen, A. Ledelsky, Rafael
P2.20 ADVANCED GRAPHITE FIBRES * D. Ronen, IMI
P2.21 CORROSION OF COMMERCIALLY PURE ALUMINUM TYPE A5 1050 DURING LONG SERVICE AT IRR2 REACTOR B. Herrmann, A. Munitz, Y. Gurevitz, C. Cotter, NRCN
'Abstract not submitted
-11- THURSDAY. FEBRUARY 25. 1993 /Continued
Poster Session P2/Continued
P2.22 TENSILE PROPERTIES OF NEUTRON IRRADIATED CO WORKED ALUMINUM 6063 ALLOY A. Munitz, F. Simca, A. Stecbmao, C. Cotler, M. Talyunker, Ben Gurion University of the Negev, S. Oahan, NRCN
P2.23 M1CROSTRUCTURE OF TIG AND ELECTRON BEAM COPPER-STAINLESS STEEL WELDS A. Munitz, C. Cotler, H. Sacham, E. Aberman, NRCN
P2.24 GROWTH OF A METASTABLE EUTECTIC IN Al-U ALLOYS SOLIDIFIED IN A COPPER MOLD A. Munitz, C. Cotler, E. Nechama, NRCN, M. Talyanker, Ben Gurion University of the Negev
P2.25 SULFUR SEGREGATION ON NICKEL SURFACES O. Segel, M. Polak, Ben Gurion University of the Negev
P2.26 POTENTIAL-CURRENT OSCILLATIONS OF TITANIUM ALLOY EXPOSED TO IN NaBR SOLUTION UNDER APPLIED POTENTIAL CONDITIONS Y. Shterenberg, D. Itznak, Ben Gurion University of the Negev
P2.27 MODEL FOR PHASE FORMATION IN THIN-FILM METAL/SEMICONDUCTOR SYSTEMS FROM AN AMORPHOUS INTERLAYER M. Beregovsky, M. Eizenberg, Technion
P2.28 ANISOTROPY IN RESIDUAL STRAINS AND LATTICE PARAMETER OF REACTIVE SPUTTER-DEPOSITED Zr FILMS A. Laor, L. Zevin, J. Pelleg, Ben Gurion University of the Negev
P2.29 BLISTERS FORMATION DUE TO HELIUM IMPLANTATION OF COPPER AND ITS ALLOYS * D. Moreno, NRCN, E. Abramov, O. Eliezer, Ben Gurion University of the Negev
P2.30 HYDROGEN INTERACTION WITH NICKEL PRE-IMPLANTED WITH He: THE EFFECT OF THE DOSE AND POST-IMPLANTATION ANNEALING E. Abramov, NRCN, Ben Gurion University, G. Solovioff, Ben Gurion University of the Negev, Y. Grinberg, NRCN, G.D. Lampert, Soreq Nuclear Center, D. Eliezer, Ben Gurion University of the Negev
P2.31 PRELIMINARY STUDY ON MICROSTRUCTURE OF Al-Be ALLOYS * M. Brill, O. Shmariau, A. AdJer, S. Harush, NRC E. Abramov, NRC, Ben Gurion University of the Negev
P2.32 STRESS CRACKING AS A RESULT OF HYDRIDE FORMATION IN U-0.1% Cr S. Zalkind, R. Ashcenazy, S. Harusb, A. Venkert, D. Moreno, D. Halperin, NRCN, E. Abramov, NRCN, Ben Gurion University of the Negev
P2.33 CVD AND MBE OF RAREFIED H2 OF SiGe SOLID SOLUTION K. Ljutovich, Uzbek Academy of Science, Uzbekistan
P2.34 TEXTURE OF URANIUM ALLOYS DUE TO PLASTIC DEFORMATION * A. Dabush, D. Dayan, G. Kimmel, Y. Dahan, M. Dariel, NRCN
*Abstract not submitted
-12- THURSDAY. FEBRUARY 25 19 9 3 /Continued
Poster Session P2/Continued
P2.35 THE INFLUENCE OF METALLIC GETER ON THE OXYGEN IMPURITY IN As-Se INFRARED FIBER • E. Nir, I. Tugendhaft, A. Bornsteln, Soreq Nuclear Research Center, N. Croitoni, Tel Aviv University
P2.36 THE BEHAVIOR OF METALS UNDER INDUCED POTENTIAL D. Itzhak, Ben Gurion University of the Negev, H. Straze, Bromide Compounds Ltd.
P2.37 HYDROGEN INDUCED BLISTERS FORMATION AND GROWTH IN NICKEL PRE- IMPLANTED WITH HELIUM G. Solovioff, Ben Gurion University of the Negev, E. Abramov, NRCN D. Eliezer, Ben Gurion University of the Negev
P2.38 THE CORROSION BEHAVIOR OF TITANIUM-ALUMINIDE ALLOYS A. Ben-Gigi, G. Solovioff, D. Eliezer, Ben Gurion University of the Negev
P2.39 HYDROGEN EFFECTS IN Al-A^Ti-SiC G. Solovioff, E. Abramov, D. Eliezer, Bin Gurion University of the Negev, EJ. Lavernia, University of California, USA
P2.40 THE CORROSION BEHAVIOR OF Al/Al3Ti/SiC N. Wertsman, G. Solovioff, D. Eliezer Ben Gurion University of the Negev, EJ. Laveroia, University of California, USA
P2.41 HYDROGEN EFFECT ON THE ORDERED ORTHORHOMBIC Ti NbAl BASED ALLOYS N. Stern, G. Solovioff, D. Eliezer, Ben Gurion University of the Negev
P2.42 PHASE FORMATION BETWEEN CO-DEPOSITED Co-Ta THIN FILM AND SINGLE CRYSTAL SILICON SUBSTRATE G. Briskin, J. Pelleg, M. Talyanker, Ben Gurion University of the Negev
P2.43 THE SOURCE OF FRINGE CONTRAST OBSERVED IN THE INTERFACE BETWEEN HELIUM BUBBLE AND CuBe ALLOY MATRIX D. Moreno, NRCN, D. Eliezer, Ben Gurion University of the Negev
P2.44 FCGR AND FRACTURE TOUGHNESS IN Ti6Al-4V OF DIFFERENT MORPHOLOGIES J. Brandelstein, Rafael, L. Levin, Technion
P2.45 THE EFFECT OF MACHINING PARAMETERS ON THE SURFACE ROUGHNESS OF Ni COATED Al MIRRORS G. Kohn, Ben Gurion University of the Negev, Y. Shneor, Rotem Industries, R. Papiar, IAI
P2.46 A NEW SELECTIVELY ABSORBING COATING T. Werber, J. Yahalom, Technion
P2.47 CONTROLLED THERMOPROTECTIVE COATINGS FOR GAS TURBINES E. Shvarzshtein, T. Werber, J. Yahalom, Technion
P2.48 THEORETICAL METHOD FOR CALCULATION OF THE DIFFUSION DEPTH C. Samoila, University of Transylvania of Brasov, Romania
'Abstract not submitted -13- \ THURSDAY. FEBRUARY 25. 1993 /Continued I Poster Session P2/Contlnued P2.49 METHODS FOR OBTAINING METALLIC MAGNESIUM FOR MODIFICATION OF NODULAR CAST IRON A. Crisan, I. Ciobanu, University of Transylvania of Brasov, Romania
P2.50 HYDRIDES FORMATION IN a2 AND TTITANIUM M. Dangur, J. Haddad, D. Eliezer. Ben Gurion University of the Negev
P2.51 Ge SINGLE CRYSTAL FILMS GROWN BY MBE ON (Ca,Sr)F/AL O AND GaAs SUBSTRATES E. Redmard, E. Grunbaum, G. Oeufsher, Tel Aviv University
P2.52 WIDE ANGLE XRD STUDY OF THE EFFECT OF PROCESSING CONDITIONS ON POLY (P-PHENYLENE BENZOBISTHIAZOLE) E.L. Garstein, Y. Cohen, Technion
P2.53 OXIDATION GROWTH IN 1NTERMETALLIC Ti-25-10-3-1 M. Dangur, D. Eliezer, Ben Gurion University of the Negev
11:15-12:45 SESSION 3.1 - ENVIRONMENTAL EFFECTS II Green Hall Chairmen: E. Abramov, NRCN M. Volf, Israel
3.1.1 SIMULATION OF HYDROGEN ISOTOPES DIFFUSION THROUGH METAL LATTICE CONTAINS CONTINUOUS ENERGY TRAPS E. Abramov, NRCN, Ben Gurion University of the Negev, N. Yakobovitcb, Israel Air Force, E. Berman, D. Eliezer, Ben Gurion University of the Negev
3.1.2 SURFACE MECHANOCHEMISTRY OF CRYSTALLINE SOLIDS E. Gutman, Ben Gurion University of the Negev
3.1.3 NON1SOTHERMAL EFFECTS DURING THE MAIN CRACK PROPAGATION IN BRITTLE MATERIALS E. Druinsky, L. Levin, R. Arone, A. Klyuch, Technion
3.1.4 THE EFFECT OF TIN AND NICKEL ADDITION ON THE ENVIRONMENTAL BEHAVIOUR OF SINTERED DUPLEX STAINLESS STEEL A. Sharon, D. Itzhak, Ben Burion University of the Negev
-14- THURSDAY. FEBRUARY 25. 1993 /Continued
11:15-12:45 SESSION 3.2 - PHYSICAL METALLURGY Kesem HaU Chairmen: t P. Moldovan, Poiytecnic Inst. Romania R. Shurck, Ben Gurion University
3.2.1 X-RAY DIFFRACTOMETRY IN MATERIALS SCIENCE L. Zevin, Ben Gurion University of the Negev
3.2.2 STUDY IN IMPROVEMENT OF WEAR BEHAVIOUR IN HIGH KINEMATIC PAIRS BY WAY OF A COMPUTER PROGRAM E. Bennan, S. I. Grunfeld, Ben Gurion University of the Negev
3.2.3 ASPECTS OF BEHAVIOUR CONCRETE MACHINE TOOL STRUCTURES USING FINITE ELEMENT METHOD C. Ispas, C. Dogariu, A. Craciunescu, Polytechnic Institute of Bucharest, Romania
3.2.4 A MODEL DESCRIBING THE CURVED ARRHENIUS PLOTS IN SELF - DIFFUSION OF METALS V. Segel, J. Pelleg, D. Fuks, Ben Gurion University of the Negev, S. Dorfman, Technion
11:15-12:45 SESSION 3.3 - CORROSION Jerusalem Hall Chairmen: J. Zahavi, Technion P. Pelted, Bromine Compounds Ltd.
3.3.1 THE INFLUENCE OF SURFACE TREATMENTS OF ALUMINUM ALLOYS ON THEIR RESISTANCE TO CORROSION FATIGUE M. Landkof, J. Rezek, A.Cohen, Rafael
3.3.2 FORMICARY CORROSION OF COPPER I. Weisshaus, A. Kaufman, E. Erdan, Orlil Ltd.
3.33 STRESS CORROSION CRACKING OF STAINLESS STEEL IN BROMIDE HEAVY BRINES P. Peled, Bromine Compounds Ltd., D. Itzhak, Ben Gurion University of the Negev
3.3.4 THE EFFECT OF MELT TEMPERTURE ON THE ELECTRICAL RESISTIVITY AND CRYSTALLIZATION TEMPERATURE OF Al -La-Ni AND Al -Ce.-Ni AMORPHOUS ALLOYS 91 5 4 91 .s 4 V. Manov, D. Shechtman, Technion, A. Rubshtefn, A. Voronel, Tel Aviv University
3.3.5 USE OF ELECTRICAL EQUIVALENT CIRCUIT TO SIMULATE SOME CASES OF PROTECTIVE COATINGS UNDER CORROSION CONDITIONS J. Hazan, J. Yahalom, Technion
-15- THURSDAY. FEBRUARY 25. 1993 /Continued
11:15-12:45 SESSION 3.4 - COATINGS II Disco Chairmen. R. Porat, Iscar Ltd. M. Pass, ORT, Israel
3.4.1 SURFACE DIFFUSION AND COATING OF SiC AND B C BY INTERACTION WITH METAL POWDERS P. Mogiltvsky, I. Gotman, E.Y. Gutmamts, Technion, WA. Kaysser, Max Planck Institute, Stuttgart, Germany
3.4.2 ELECTROPHORETIC DEPOSITION OF HYDROXYAPATICE COATINGS FOR MEDICAL APPLICATIONS A. Zhitomirsfcy, L. Gal-Or, Technion
3.4.3 M1CROSTRUCTURE, PHASE COMPOSITION AND RESIDUAL STRESSES IN PLASMA SPRAYED THERMAL BARRIER COATINGS M. Levit, S. Berger, BZ. Weiss, Technion
3.4.4 PRODUCTION OF Cr BASED COMPOSITE COATINGS IN THE PRESENCE OF ADDITIVES O. Berth, S. Eskln, J. Zahavi, Technion
3.4.5 DIAMOND COATINGS Z. Klein, A. Markovitch, A. Shalmon, Rafael
12:45-14:00 Lunch Break Dinine Room
14:00-15:30 SESSION 4.1 - MECHANICAL Jerusalem Hall BEHAVIOUR OF MATERIALS Chairmen: N. Nir, Rafael J. Haddad, Ben Gurion University
4.1.1 MECHANOCHEMICAL METHODS IN MATERIAL SCIENCE PJ. Butyagin, Russian Academy of Science, Russia
4.1.2 RESIDUAL MECHANICAL PROPERTIES OF ABLATIVE COMPOSITES ON EXPOSURE TO HIGH TEMPERATURES H. Weisshaus, I. Engelberg. ADA
4.1.3 STRESS AND FAILURE ANALYSIS OF TAPERED ADHESIVE JOINTS A. Buchmao, F. Weinstein, Y. Holdengraber, I. Honigman, H. Dodiuk, Rafael
4.1.4 FATIGUE MECHANISMS OF 95/5 Pb/Sn MICRO SOLDER JOINTS UNDER FULLY REVERSED SHEAR N. Nir, AT&T Bell Laboratories, USA, A.R. Storm, T.D. Dudderar, Rafael
4.1.5 FRACTURE TOUGHNESS MEASUREMENTS FOR CERAMIC MATERIAL A. Ashur, A. Cohen, Rafael THURSDAY. FEBRUARY 25. 1993 /Continued
14:00-15:30 SESSION 4.2 - COMPOSITE MATERIALS II Kesem Hall Chairmen: L. Zevin, Ben Gurion University C. Samoila, Univ of Transylvania
4.2.1 THE EFFECT OF IMPURITIES ON THE TENSILE ELONGATION OF BERYLLIUM 0. Yeheskel, NRCN
4.2.2 THE PREPARATION OF FIBER REINFORCED ALUMINUM SiCT/6061 BY DIFFUSION BONDING M. Paz, J. Mironi, N. Atzmon, M. Elkaiyam, Israel
4.2.3 COMPARATIVE STUDIES CONCERNING THE BEHAVIOUR OF RESIN/FIBRE GLASS COMPOSITE MATERIALS 1. Constantly Polytechnic Institute of Bucharest, G. Dan, S.C Simtex, Romania
4.2.4 RECRYSTALLIZATION OF TUNGSTEN BASE HEAVY METAL ALLOYS C. Weinberger, D. Chaiat, TAAS Israel Industries Ltd.
4.2.5 LASER SURFACE ALLOYING OF FERROUS ALLOYS WITH CrB : SOLIDIFICATION BEHAVIOUR AND MICRO-STRUCTURE G. Shafirstein, M. Bamberger, Technion, S. Aricly, F. Maisenhalder, M. Langohr, DLR Stuttgart, Germany
14:00-15:30 SESSION 4.3 - MATERIAL PROCESSING II Green Hall Chairmen: I. Ciobanu, Univ. of Transylvania S. Moisa, Ben Gurion University
4.3.1 ULTRASONICS AS A RESEARCH TOOL IN POWDER TECHNOLOGY O. Yeheskel, H. Klimker, Y. Gefen, M. Ganor, NRCN
4.3.2 EFFECT OF PROCESSING ON MICROSTRUCTURE AND PROPERTIES OF TUNGSTEN HEAVY ALLOYS E.Y. Gutman, D. Zack, D. Chaiat, Technion
4.3.3 STRUCTURAL CHARACTERIZATION OF EPITAXIAL THIN FILMS BY RECIPROCAL SPACE MAPPING G.H.O. Daalderop, T.R. Ryan, Philips Analytical X-Ray, The Netherlands
4.3.4 MICROSTRUCTURE OF Al-U ALLOYS SOLIDIFIED AT COOLING RATES BETWEEN 0.03-0.5 K/SEC A. Munitz, V.Y. Zenou, C. Cotier, A. Zahavi, Z. Barkai, NRCN
4.3.5 IMPROVING PRODUCT DESIGN THROUGH A CONTROLLED EXPERIMENT B. Milman, 1. Sirota, TAAS Israel Industries, D.M. Steinberg, Tel Aviv University
-17- THURSDAY. FEBRUARY 25. 1993 /Continued
14:00-15:30 SESSION 4.4 THIN FILMS II Chairmen: M. Polak, Ben Gurion University D. Borochov, Israel
4.4.1 COMPUTERIZED SYSTEM FOR EVALUATION OF ENERGY ABSORPTION DURING LASER TREATMENT OF METALS M. Geller, E. Armon, M. Bamberger, Technion
4.4.2 THE INTERFACE FORMED BETWEEN PbBiSrCaCuO HIGH-T SUPER- CONDUCTOR CERAMIC AND Ag OR Ag-BASED ALLOYS N. Froumin, J. Baram, M. Polak, Ben Gurion University of the Negev
4.4.3 DEPOSITION OF DIAMOND-LIKE CARBON FILMS BY LASER PLASMA TECHNIQUE J. Karpmao, M. Riabkina-Fishman, J. Zahavi, Technion
4.4.4 RECONSTRUCTION OF SURFACE AND ENVIRONMENTAL SENSITIVE MECHANICAL BEHAVIOR OF METALS EX. Glickman, The Hebrew University of Jerusalem
4.4.5 THE NEW METHOD OF CRYSTAL PERFECTION CHARACTERIZATION USING X-RAY BRAGG REFLECTIONS Y. Rosenberg, Tel Aviv University
15:30-15:45 Coffee Break Foyer
15:45-16:15 CLOSING SESSION Green Hall Chairman: D. Itzhak, Ben Gurion University
-18- AUTHORS' INDEX
E. Aberman P2.23 D ,G. Brandon PI.26, PI.48, PI.50, T. Aboud PI. 22 PI.51, PI.52, 2.1.3 E. Abramov 2.2.2, 2.2.4, 3.1.1 A . Brofcnan 1.4.3 P2.29, P2.30, P2.31, E . Broyk-Levinaon P2.7 P2.32, P2.37, P2.39 M .V. Bruum C-l A. Adler P2.31 A . Buchman 4.1.3, PI. 35 U. Admon 1.4.4, PI. 30 P .J. Butyagin 4.1.1 D. Aizenman 2.4.3 L N. Bystrov P2.13, P2.14 M. Alaluf 2.4.3 M Carean PI. 28 C. Alexandru, PI.17, PI. 19 R L. Carlin PI. 21 D. Alperstein 1.1.2 D Chaiat 4.2.4 J.E. Angelo B-3 D Chalat 4.3.2 S. Ariely 4.2.5 R Chaim 1.2.4 N. Arishkevich 2.3.1 Y Chakks 1.3.4 E. Armon 4.4.1 B. Chen PI.47 R. Arone 3.1.3, PI.4 V.T. Chernenko, PI. 20 R. Ashcenazy P2.32 I. Ciobanu P2.49 A. Ashkenazi PI. 23 A. Cohen 3.3.1, 4.1.5, P2.19 A. Ashur 4.1.5 Y. Cohen P2.52 N. Atzmon 4.2.2 C. Conn 2.4.1 Z. Atzmon 2.4.5 I. Constantin 4.2.3 O. Atzmony, PI. 18 C. Cotler 4.3.4, P2.21, P2.22, M. Auslander P2.1 P2.23, P2.24 Y. Avigal 1.3.2 K. Cowie 1.2.5 Y. Avrahamov PI.44, PI.45 A. Craciunescu 3.2.3 M. Ayzenberg-Stepanenko P2.16 A. Crisan P2.49 N. Bacharach PI.44 N. Croitoru 2.4.3, P2.35 Y. Bainer P2.17 R. Cytermann, PI.31 M. Bamberger 1.2.3, 4.2.5, 4.4.1 G.B.O. Daalderop 4.3.3 A. Bar PI. 16 A. Dabush P2.34 J. Baram 4.4.2 I. Dahan 1.3.5 B. Barkai PI.8 S. Dahan P2.22 Z. Barkai 4.3.4 Y. Dahan P2.34 Y. Baruch P2.3 S. Dan 4.2.3 S. Bar Ziv P2.19 M. Dangur P2.50, P2.53 M-][. Baskes, B-3 H.V. Dariel 1.4.4, PI .18 L. Baum PI. 26 M.S. Dariel PI.30, P2.34 V. Belov 2.4.4 D. Dayan P2.34 A. Ben-Gigi P2.38 S. Darwish, PI.9 A. Bentur PI. 37 B. Deutsher P2.51 H. Beregovsky P2.27 S.F. Dirnfeld 1.3.2 S. Berger 1.3.4, 3.4.3, PI.29 H. Doduik 4.1.3, PI. 35 A. Berner PI.33, PI. 34 C. Dogariu 3.2.3 0. Berkh 3.4.4, PI. 32 M. Dollar C-3 E. Berman 3.1.1, 3.2.2 S. Dorfman 3.2.4 A. Bettelheim PI. 40 E. Druinsky 3.1.3 A. Bluvstein PI.53 T.D. Dudderar 4.1.4 M. Boas 1.2.3 M. Eizenberg 2.4.5, P2.27 N.BI. Bochvar P2.13 0. Elias PI. 38 A. Bornstein P2.35 D. Eliezer 1.3.5, 2.2.3, 2.2.4, B. Bousfield 2.2.1 2.2.5, 3.1.1, P2.9, P2.29 J. Brandelstein P2.44 P2.30, P2.37, P2.38 M. Brill P2.31 P2.39, P2.40, P2.41 G. Briskin P2.42 P2.43, P2.50, P2.53 M. Elkaiyan 4.2.2
-39- I. Engelberg 4.1.2 D. Itzbak 3.1.4 . 3.3.3, PI. 30 E . Erdan 3.3.2 PI. 38 , PI.49, P2.26 S . Eskin 3.4.4, PI. 32 P2.36 L . Farber 1.3.3 E. Jacobsohn PI. 46 A . Payer 1.3.2 D. Julean, PI. 28 S . B. Fazluddin 1.2.5 A .H. Katan C-2, 1.3.1 B . Feldman P2.15 W .D. Kaplan PI. 26 , PI.50, PI.52 I. Feldman P2.18 N. Karai PI. 6 S .M. Foiles, B-3 J . Karpman 4.4.3 N . Froumln 4.4.2 A.. Katsman 1.4.1 , 1.4.5 D . Fuks 2.3.3, 3.24 A . Kaufman 3.3.2 , P2.15 L . Gal-Or 3.4.2 W .A. Kaysser 3.4.1 T.. Gambaryan PI. 12 L.. Kerekes, PI. 28 M . Ganor 2.3.3, 4.3.1 E,. Khodakovskaya 2.1.4 -1 E..L. Garstein P2.52 H.G. Kilian 1.1.3 r I.. Gavish PI. 3 G.. Kimmel 1.4.4 , P2.2, P2.34 y.. Gefen 4.3.1 N.. Klein 1.2.1 M.. Geller 4.4.1, P2.7 Z.. Klein 3.4.5 A.. Geltz 2.3.1 J.,E. Klemberg-Sapieha 2.3.4, PI.40 G. V. Gtaica PI.17, PI. 19 H.. Klinker 4.3.1 I.. Gilad P2.6 L.. Klinger 1.4.1 . 1.4.5 E.. Glickman 1.4.5, 4.4.4 A., Klyucb 3.1.3 , PI.27 0., Glozman PI. 26 G., Kobn P2.45 M., Gluzman P2.1 Y., Komem PI. 23 , PI.43, PI. 44 I. Goldfarb 1.4.2, PI.11, PI.34 M. Konrad, Pl.l A. Goldstein 2.4 4, PI. 16 D., Kopeliovich, PI.10 D. Golodnit8ky PI. 15 L. Kornblit P2.1 I. Gotman 3.4.1, PI. 14 A. Koursaris 1.2.5 H.J. Grabke C-l K. Kovler PI.37 A. Grinberg P2.17 M. Kravchik 2.4.4 , PI.16 Y. Grinberg P2.30 G.D. Lampert 1.1.4 , P2.30 E. Grunbaum P2.51 M. Landkof 3.3.1 S. I. Grunfeld 3.2.2 J. B. Lando B-l B. Grushko P2.10 J. Lanfir PI. 32 6. Gurevitz Pl.l M. Langohr 4.2.5 Y. Gurevitz P2.21 A. Laor P2.28 E. Gutman 3.1.2, PI.49, P2.17 E.J. Lavernia P2.ll , P2.39, P2.40 E.Y. Gutman 4.3.2 F.A. Lecki 2.1.2 E.Y. Gutmanas 1.3.3, 3.4.1, PI.14 A. Ledelsky P2.19 J. Haddad 2.2.5, P2.50 I. Lerner PI.23 D. Halperin P2.32 Y. Lerner PI. 36 H. Harel PI.42 I. Lev PI. 38 S. Harush P2.31, P2.32 C.G. Levi 2.1.1 J. Bazan 3.3.5 A. Levio 1.4.1,, 1.4.5 B. Herrmann P2.21 I. Levin 2.1.2,, 2.1.3 Y. Holdengraber 4.1.3 L. Levin 3.1.3, P2.44 I. Honigman 4.1.3 M. Levit 3.4.3 R. Huberman PI. 49 S. Libov P2.3, P2.4, P]L.25 E. Igner PI. 25 L. Lifenitz 1.1.4 S. Incardona 1.2.2 E.Y. Litovsky, PI.12, PI.13, PI. 31 a. Interter 2.3.2 K. Ljutovicb P2.33 c. Ispas 3.2.3 A. Loksh, PI.4 D. Lotker 2.3.3 F. Maisenhalder 4.2.5 Y. Man P2.15
-20- A. Manuchin P2.7 I. Roman PI. 5 E. Manor 2.1.1 T.M.F. Ronald A-l R.R. Manory P2.2 D. Ronen P2.20 V. Manov 3.3.4, P2.7, P2.8 Y. Rosenberg 4.4.5, P2.18 A. Markovitch 3.4.5 M. Rotel PI.35 L. Martinu PI. 40 A. Rubshtein 3.3.4 6. Marom 1.1.3, 1.1.4, 1.2.1, R.G. Rowe A-2 1.2.2, PI.42 T.R. Ryan 4.3.3 L. Martinu 2.3.4 H. Sacham P2.23 J.W. Mayer 2.4.5 C. Samoila P2.48 A.K. Mehlmann 1.3.2 J. Sariel 1.4.4, PI.47 R. Mehrabian 2.1.1 M. Savransky, PI. 29 E.H. Men PI. 48 F. Schaffler 2.4.5 C. Migliaresi PI.42 R.B. Schwarz B-2 B. Milman 4.3.5 0. Segel P2.25 J. Mlroni 4.2.2 V. Segel 3.2.4 A. Mittelman PI. 24 Y. Shacham-Diamand 2.4.5 P. Mogilevsky 3.4.1 6. Shafirstein 4.2.5 F. Moldovan PI.17, PI.19 N. Shafry Pi.51 N.R. Moody, B-3 A. Sbalmon 3.4.5 R. Mor PI.45 M. Shapiro PI.12, PI.13 D. Moreno P2.9, P2.29, 2.2.4, 6. Sharshukov PI.4 P2.32, P2.43 A. Sharon 3.1.4 S.I. Morozov, PI. 20 E.N. Shauly PI.43, PI.44, PI.45 A. Munitz 4.3.4, P2.21, P2.22, R. Shaviv PI.21 P2.23, P2.24 D. Shechtman 1.4.2, 3.3.4, P2.8, 6. Nahor 1.1.4 PI.22, PI.34, PI.46 M. Narkis 1.1.1, 1.1.2 D. Sherman 2.1.2 N. Nawi, PI. 30 D. Shmariau P2.31 E. Nechama P2.24 R. Shneck 1.4.3 Y. Neiman, PI.2 Y. Shneor P2.45 H. Ni 2.1.1 Y. Shterenberg P2.26 E. Nir P2.35 M. Shuster 1.1.1 N. Mir 4.1.4 E. Shvarzshtein P2.47 P.D. Odessky, PI. 20 A. Siegmann 1.1.1, 1.1.2 I. Odler PI. 37 F. Sifflca P2.22 R. Papiar P2.45 I. Sinitsky PI.48 E. Paransky, PI. 14 I. Sirota 4.3.5 A. Pasternak, PI. 2 L.I. Slepyan P2.12, P2.16 M. Paz 4.2.2 G. Solovioff 2.2.3, P2.30, P2.37, E. Peled, PI. 15 P2.38, P2.39, P2.40, P. Peled 3.3.3, PI.38 P2.41 J. Pelleg 2.3.3, 3.2.4, PI.9 V. Stancovsky 2.4.4, PI.16 P2.28, P2.42 A.B. Steblov, PI.20 M. Polak 4.4.2, P2.25 A. Stechman 1.4.4, P2.22 L.C. Phillips C-2, 1.3.1 M. Steihorst C-l R. Porat PI.3, 1.3.2, 2.3.1 D.M. Steinberg 4.3.5 L. Potepun PI. 4 A. Stern C-2, 1.3.1, 1.3.5 V.P. Privalko 1.1.3 N. Stern P2.41 A. Raveb 2.3.4, PI.40 S. Stolyarova PI.39 E. Radmard P2.51 A.R. Storm 4.1.4 J. Rezek 3.3.1 H. Straze P2.36 M. Riabkina-Fisbman 2.4.2, 4.4.3 V. Strelcov PI.54 I. Riess PI.41 M. Talyanker P2.22, P2.24, P2.42 C. Ringas 1.2.5 S. Tamir PI.36
-2\~ A . Teishev 1.2.2 0 . Tevet PI. 18 A. Tregub 1.1.3 , PI.,42 A .B. Tsepelev P2.14 I.. Tugendhaft P2.35 K.. Urban P2.10 M.R. Uritsky, PI. 20 S.. Ustilovsky, PI. 4 V.,M. Ustinovshchikov P2.13, P2.14 A.. Venkert P2.32 R. Vered 1.1.4 A. Voronel 3.3.4 T. Wagner PI.2 C. Weinberger 4.2.4 F. Veinstein 4.1.3 B.Z. Weiss 1.3.4,, 3.4.3 , PI.29 H. Weisshaus 4.1.2 I. Weisshaus 3.3.2 T. Werber P2.46,, P2.47 H.R. Wertheimer 2.3.4,, PI.40 N. Wertsman P2.40 R. Wittoann P2.10 J. Yahalom 2.3.2 3.3.5, P2.46, P2.47 N. Yakobovitch 3.1.1 I. Yaniv PI. 31 0. Yeheskel 2.3.3, 4.2 .1,, 4.3.1 PI. 18 M. Yelin P2.4 P. Yoffe P2.3, P2.4 , P2.5 D. Zack 4.3.2 A. Zahavi 4.3.4 J. Zabavi 2.4.2, 3.4 • 4, 4.4.3 PI.32, PI.35, PI. 36 S. Zalkind P2.32 E. Zaretsky PI.6, PI.7 F. Zeides, PI. 5 V.Y. Zenou 4.3.4 h. Zevin 1.4.4, 3.2 .1 P2.28 PI. 32 A. Zhitomirsky 3.4.2 E. Zolotoyabko PI.34, Pl.t46
-22- ABSTRACTS
1 I
PLENARY SESSIONS \ STRUCTURAL MATERIALS FOR NASP I Terence M.F. Ronald
NASP Joint Program Office
Wright-Patterson Air Force Base
Ohio 45433, USA
The materials classes of primary interest for the NASP X-30 experimental vehicle include
titanium alloys, titanium-based metal-matrix composites, carbon-carbon composites, ceramic
matrix composites. On the airframe, these materials would be used as lightweight skin
panels of honeycomb-core, Iruss-core, or integrally stiffened thin sheet configuration.
Where necessary, they would be cooled with the gaseous hydrogen fuel by incorporating
coolant passage into the structure. In the engines, they would be used in the hot gas
path of the ramjet/scramjet, and also in the inlet and nozzle areas. The engine
application represents a particularly challenging problem because of the severe
environment, involving high thermal, acoustic and mechanical loading. In this case, the
structural components almost certainly will be actively cooled, meaning that the materials
may be in contact with hot hydrogen from the fuel, in addition to hot oxygen and the
gaseous products of combustion.
I
A-l MICROSTRUCTURE, PHASE TRANSFORMATIONS AND MECHANICAL
PROPERTIES OF ORDERED ORTHORHOMBIC Ti2NbAl-BASED ALLOYS R.G. Rowe GE Corporate Research and Development,
Schnectady, NY 12309, USA
Titanium aluminide alloy and process development for the past decade has centered upon balancing elevated temperature strength and creep resistance with room temperature fracture toughness and ductility. Ordered orthorhombic Ti2NbAl-based alloys lie upon a new higher strength vs. fracture toughness curve than conventional titanium aluminides. This has made them attractive candidates for elevated temperature aircraft and aerospace applications in both monolithic and composite form. The tensile and creep properties of these alloys will be described as a function of microstructure and quaternary alloy additions. Their transformation behavior, and equilibrium phase relations, which are less well established than for conventional titanium aluminides, will be reviewed. Changes in grain boundary structure have been observed during long time creep exposure for grain boundaries under normal applied stress. The relationship of these changes to the transformation behaviour of the alloys will be discussed.
A-2 I ATOMISTIC SIMULATION OF HYDROGEN-INDUCED FRACTURE OF AN IRON- | BASED SUPERALLOY N.R. Moody, S.M. Foiles, J.E. Angelo, and M.I. Baskes Sandia National Laboratories, Livermore, CA 94551-0969
Austenitic supetalloys are often used in hydrogen and hydrogen-producing environments due to their good resistance to hydrogen effects compared with other alloy systems. Nevertheless, these alloys can exhibit dramatic reductions in ductility and crack growth resistance when exposed to high hydrogen fugacity environments. We studied the effects of high fugacity hydrogen in the crack growth susceptibility of one of these superalloys, IN903. This work showed that the resistance to crack growth decreased by a factor of three when exposure to hydrogen triggered a change in fracture mode from microvoid coalescence to intergranular failure. Although the grain boundaries are known trap sites for hydrogen, the effects of hydrogen on the intergranular fracture process are not well- defined, being attributed to a either a decrease in atomic bond strength or to the enhancement of localized plasticity. Neither of these mechanisms are verifiable through direct observation in bulk samples using currently available techniques. As a consequence, we combined Monte Carlo and molecular dynamics calculations with the embedded atom method (EAM) to help to define the effects of hydrogen trapping on the fracture of grain boundaries through simulation. For all lattices, fracture began by the breaking of bonds next to the polyhedral defects that characterize the boundary structure followed by rapid failure of the remaining bonds across the boundary plane. These simulations showed that hydrogen did not alter the sequence of events comprising the fracture process but did lower the fracture stress from 18 GPa to a lower limiting value of 8 GPa as the trap sites along the boundary plane filled. The hydrogen atoms in these sites were the only hydrogen atoms involved in the fracture process. Within the constraints imposed in these calculations, the results of this study showed that the "inherent" effect of hydrogen is to reduce the cohesive force between atoms across the boundary. This presentation will discuss these results and their impact on our understanding of how hydrogen affects fracture in iron and nickel-rich superalloys.
This work supported by U.S. DOE Contract DE-AC04-76DP00789 and the Office of Basic Energy Sciences, Division of Materials Science.
H-J I OXIDATION BEHAVIOUR OF INTERMETALLIC PHASES FOR HIGH I TEMPERATURE APPLICATION 1 H.J. Grabke, M. Steihorst and M.W. Brumm j Max-Planck-Institut fur Eisenforschung, Diisseldorf, Germany
The oxidation behaviour of NiAl, NbAl3 and different alloys from the system Ni-Nb-Al was investigated in the temperature range 700-1400°C.
NiAl proves to be rather oxidation resistant, at high temperatures > 100°C protective AI2O3 scales are formed. But, the oxidation, especially of NiAl with Ni excess, leads to cavity formation beneath the scale and spalling of the scale. Between 800-1000°C at first metastable AI2O3 - modifications are formed which gradually transform to a - AI2O3, this transformation is accelerated for NiAl-Cr alloys. Local attack of NiAl under internal oxidation and outgrowth of Ni/A^O^ protrusions was observed under special conditions, low p<>2 and intermediate temperatures.
Under corresponding conditions NbAl3 shows "pesting", i.e. disintegration into fine oxidized particles. This phenomenon is initiated by oxygen diffusion into grain boundaries and AI2O3 precipitation at the grain boundaries, as shown by Auger electron spectroscopy. But also at high temperatures > lOOO'C NbAl3 is not oxidation resistant, since upon cracking of the AI2O3 scale the Nb2Al formed below the scale is oxidized under formation of fast growing oxides - a stratified scale of A2IO3 and of AlNbC>4 and layers is obtained.
In contrast to the single phase materials some multiphase alloys behave much better, concerning as well the oxidation at intermediate temperatures (no pesting) as the high temperature oxidation, e.g. NiAl-Cr, NiAl-NbNiAl and NiAl-NbNiAl-NbAl3.
c-i ELECTROMAGNETIC MONITORING OF METAL PROCESSING Arnold H. Kahn*. Louis C. Phillips* and Adin Stern** *National Institute of Standards and Technology, Gaithersburg, MD 20899, U.S.A. I ' **Israel Atomic Energy Commission, Nuclear research Center-Negev, f Beer Sheva 84190, Israel
Electromagnetic methods provide excellent means of non-contact sensing of properties of metals during processing. In the applications to be described, eddy currents are induced in the material under test by a primary exciting coil, which applies an ac magnetic field to the material. A secondary coil, the pickup, responds to the field as modified by the currents induced in the test material. The response depends upon the electrical conductivity and magnetic permeability of the material, its defects and inhomogeneities, and on its geometric shape and dimensions. Greatest information is obtained by sweeping the frequency of excitation, so as to probe varying depths of the material. In the cases to be discussed we shall be concerned with simple uniform shapes such as uniform sheets and cylindrical rods. In the application to the measurement of the temperature of aluminum sheets we utilize the temperature dependence of the electrical resistivity of the material. The electrical resistivity of a dilute alloy of aluminum is that of pure aluminum plus additive contributions associated with alloying composition, the degree of solid solution of the components, and the metallurgical state. In cases of controlled conditions with varied composition we have been able to perform on-line eddy current monitoring of the temperature of moving aluminum sheet, in the range of 300° to 400°C, to an accuracy of + 16°C. For the range of compositions used there would have been an apparent spread of 60°C. Fluctuations in the temperature of the moving sheet limited the precision; with improved control the accuracy demonstrated would have been higher. Further testing is ' in progress. Four additional applications will be discussed briefly. 1.) In the hot isostatic pressing and consolidation of metal powders, eddy current methods have been used to monitor the dimensions of a cylindrical canister containing the powders and thereby to obtain as in situ measurements of density during the processing. 2.) An application to the measurements of the resistivity of carbon-carbon sheet during heat treatment has been accomplished using a through transmission technique similar to that used for aluminum, but at higher frequencies. 3.) The method is also being applied to the determination of the depth of case hardening of steel shafts. Here magnetic and electrical changes due to case hardening are detected. 4.) An application to measuring the velocity of liquid metal flow in now under way in at NIST.
C -2 r
TECHNICAL SESSIONS I f POLYMERIC ANTDPLAOTICIZATION POLYCARBONATE WITH I POLYCAPROLACTONE I M. Shuster*, M. Narkis*, A. Siegmann** •Department of Chemical Engineering ••Department of Materials Engineering Technion-Israel Institute of Technology, Haifa 32000, Israel
Physical blends of polycarbonate (PC) with polycaprolactone (PCL), containing 0-30% PCL were prepared by melt mixing. The compatible blends were studied using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), mechanical testing, rheological and density measurements. Yield strength, elastic modulus and density of the blends were found to attain maximum values, depending on PCL content,
while Tg continuously decreased. PCL presence resulted in the embrittlement of PC as detected by impact and tensile tests. Simultaneously, the PC's P-transition intensity was depressed, as detected by DMA. Activation energy of PC secondary relaxation process was found to be somewhat higher for PC/PCL blends than for PC. Thus, local, intermolecularly non-cooperative motions, usually associated with ^-relaxation, are restricted in the presence of PCL. The addition of PCL to PC results in increased shear sensitivity and lower high shear rates viscosity; improving processability.
i.i.i DIELECTRIC & DYNAMIC MECHANICAL CURE MONITORING OF POLYESTER RESIN: MOLECULAR INTERPRETATION * D. Alperstein, A. Siegman, M. Narkis Technion-Israel Institute of Technology, Haifa 32000, Israel
Dielectric measurements as a mean to monitor polymeric resins during cure has gained much interest. This is due to the accuracy of this method, especially in light of the recent technological breakthroughs in producing accurate, easy to use sensors. In spite of its increasing popularity only a few basic phenomenological principles are currently understood concerning the dielectric relaxation during cure. Moreover, molecular insight to the dielectric relaxations is rare due to the vast complexity of dealing in molecular terms with a constantly changing polymer. f<
In order to partially overcome few of these obstacles unsaturated polyester was chosen as a ; model system for its relative chemical simplicity.
In this system the curing process involves only crosslinking with no chemical changes of the ester groups. Hence, the dielectric relaxation should reflect molecular rearrangements only due to network formation. In order to elaborate the frequency range, two additional dynamic methods were used: (1) Compressive dynamic mechanical method simultaneously with the dielectric measurements, (2) Dynamic rheometry. :
The results show a frequency influence on the molecular motion causing the relaxation. In the dielectric and mechanical measurements very fast molecular vibration modes can be followed. Such fast modes take place short time after the gel-point. At this stage of the curing process the polymer network is still loose, having a low crosslinking density. This loose network, swollen with most of the styrene monomer (the gel-point is at about 6% conversion), enables these fast molecular vibration modes. The rheological results show, however, relaxation at very high conversion which corresponds to slow vibration modes in a highly crosslinked network. The general origin of all molecular motions during cure is «• demonstrated by applying the same power law to all relaxation times, from the resin to the highly crosslinked network. •'
i. i. ? f THERMOELASTICITY OF FIBER / MATRIX INTERFACIAL INTERACTION IN POLYMER COMPOSITE MATERIALS A. Tregub*, G. Marom*, V.P. Privalko**, H.G. Kilian*** *Casali Institute of Appl. Chemistiy, Graduate School of Appl. Science and Technology, } } The Hebrew University of Jerusalem, Jerusalem 91904, Israel i **Institute of Macromolecular Chemistry, Academy of Science of Ukraine, 48 Kharkov Shaussee, Kiev, 252160, Ukraine ***Abt. Exp. Physik, University of Ulm, Oberer, Eselsberg, Ulm D7900, Germany It is well known, that structure and properties of the fibre/matrix interface have a pronounced effect on the mechanical performance and physical properties of composite materials [1]. Different methods for characterizaton of the fiber/matrix interface exist, including pull-out, microdebonding, fragmentation (critical length) and fibre push-out (indentation) tests. [2]. Such methods do not provide a thermodynamic description of the microfailure process, and, particularly, they do not enable to determine the onset of microfailure more precisely then ordinary visual techniques. The thermoelasticity approach, based on simultaneous measurements of the mechanical work and of the concomitant heat, exposing two aspects of the deformation of the material (developed for polymers (3|), was applied in investigating the fiber/matrix interaction in composites. In particularly, it was intended to expand our studies of poly-(etheretherketone) (PEEK)/carbon fibre composites (designated APC). The experiments were carried by a Thian-Calvet type deformation microcalorimeter [4]. First, the thermoelastic approach was applied for experimental and theoretical treatment of PEEK matrix. The thermoelastic behaviour of PEEK was typical of the polymeric glass, in both the elastic and the plastic regions. The experimental deformation dependences of the energetic effects were in accordance with Kilian's model describing the elastic and plastic deformation of a polymeric glass as a united process [5].
Consecutively, an investigation of model microcomposite samples (consisting of an isothermally crystallized at 25°C J-Polymer matrix with carbon fibers) was performed. For that microcomposite, after the said thermal treatment a transcrystalline layer was clearly observed along the fibers. Testing was performed on a pure matrix film and on matrix with either one longitudinal or two transverse fivers. The idea was to compare the thermodynamics of stretching of the pure matrix and of the microcomposites, and to reveal the contribution, if any, of a -« transcrystalline layer. Unfortunately, no meaningful difference in the energetic effects of stretching was discovered between the samples, probably, because the fiber volume fraction was 1 too low to separate the contribution of fivers and transcrystalline layers from that of the matrix. However, the measurements of the heat of stretching allowed to describe the deformation behaviour of the investigated samples more accurately, than routine mechanical force measurements. I REFERENCES
1 1. D. Hull, An Introduction to Composite Materials, Cambridge University Press, Cambridge, J.I 1981. 2. M. Narkis, E.J.-A. Chen and R.B. Pipes, Polym. Comp., 9, 245 (1988). 3. H.-G. Kilian, Th. Vilgis, Coll. Pol. Sci., 262, 15 (1984). 3. H.-G. Kilian, G.W.H. Hohne, Termochimia Ada, 69, 199 (1983).
4. J.A. Koene, B. Heise and H.-G. Kilian, J. Polym. Sci.: Polym. Phys. Ed.,27, 1235 (1989).
I.I. i
DEGRADATION OF POLYMERS BY HYPERTHERMAL ATOMIC OXYGEN
R. Vered*, G. Nahor*, G.D. Lempert*. G. Marom**, Y. Lifshitz* * Applied Physics & Mathematics Department, Soreq NRC, Yavne, Israel **Kasali Institute, Hebrew University, Jerusalem, Israel
Degradation of polymers by hyperthermal atomic oxygen and other hyperthermal species occurs in a variety of practical systems including external surfaces of spacecraft in low earth orbits (LEO), i.e. at altitudes of 200-800 km. The impact of a spacecraft orbiting at 8 km/sec with the residual atomic oxygen yields an equivalent oxygen energy of 5 eV resulting with a significant erosion especially of polymeric surfaces.
In the present work the effects of hyperthermal species on two polymers commonly used for space applications (Kapton H and Teflon FEP) were investigated. The polymers were exposed to O+ and Ne+ influence of 1017 - 1019 ions/cm2 at energies of 30 eV and 20 keV. A variety of phenomena associated with the degradation of these polymers were investigated including total mass loss release of gaseous fragments during bombardment (RGA), surface morphology (SEM) and surface chemical composition (XPS).
The experimental data will be presented and the influence of energy and type of the bombarding species will be analyzed. The relative significance of the collisional and chemical effects for the different polymers will be discussed.
The relevance of the present study to space simulation of atomic oxygen (ATOX) effects in polymers will be evaluated.
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TRANSCRUSTALLINTTY EM THERMOPLASTIC COMPOSITES AND ITS INFLUENCE ON THEIR MECHANICAL PERFORMANCE f Nava Klein, Gad Marom f* Casali Institute of Aplied Chemistry, Graduate School of Applied Science and Technology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel Thermoplastic matrix composites have been developed in recent years to replace thermoset composites for a number of reasons including their higher fracture toughness and unlimited shelf life. When a fiber is embedded in a thermoplastic semi-crystalline resin, heterogeneous nucleation may occur. In a case where there is high density of nucleation sites along the fiber surface, a columnar layer of crystals known as transcrystalline layer will develop around the fiber. Although the presence of the transcrystalline layer has been reported, the mechanism by which transcrystallization occurs is not fully understood. Moreover, a method that will predict its creation has not been offered yet.
Since the transcrystallization is known to be a nucleation-controlled process, it depends strongly on thermodynamic conditions such as the crystallization temperature or the cooling rate. Other factors, found to affect its appearance, are the topology and surface coating of the fibre, the thermal history, thermal conductivity mismatch between fiber and matrix, high surface free energy of the fiber and presence of stresses at the fiber/matrix interface.
The distinct morphology of the transcrystalline layer leads to different mechanical properties compared with the bulk resin. However, the effects of the transcrystalline layer on the composite mechanical properties are still unclear, and so the role of a •» transcrystalline interface in compositees is not conclusive.
The objective of the research was to discover the main factors that determined the transcrystallinity process and the mechanism by which its presence affected the mechanical properties of the composites. The kinetics of the transcrystallization process in isothermal conditions were studied using samples of microcomposites on a hot stage, examined by a polarizing microscope. The microcomposites consisted of either pitch- based carbon fibers or aramid fibers, embedded in Nylon 6,6 resin. The kinetics data were used to calculate energy parameters, using a modified heterogeneous nucleation mechanism.
The ability to control the transcrystalline layer and, in turn, its influence on the performance of composite materialsd would result in manufacture process optimization.
i. :\ i POL VETH YLENE FIBRES - POLYETHYLENE MATRIX COMPOSITES: PREPARATION AND PHYSICAL PROPERTIES
A. Teishev*, S. Incardona**, and G. Marom*
*Casali Institute of Applied Chemistry Graduate School of Applied Science and Technology The Hebrew University, 91904 Jerusalem, Israel **Department of Materials Engineering The University of Trento Mesiano 38050, Trento, Italy
A major disadvantage of high-strength ultra high modulus polyethylene (UHMPE) fibers, restricting their application in composite materials, is their chemical inertness, that prevents their bonding to polymer matrices. The present research is an attempt to embed UHMPE fibers (SPECTRA 900 and 1000) in high-density polyethylene (HDPE) matrix. Because of the chemical similarity of the composite components good bonding at the fiber-matrix interphase could be expected, while because of their different physical states and melting points (melting temperatures are about 130°C and I50°C for the matrix and the fiber, respectively) the molding of the composites is feasible. The effect of various processing conditions on the ultimate material properties was also investigated, as it was expected to determine the microstructure of the composite.
The matrix, the fiber and unidirectional composite laminae were studied using thermomechanical analysis (TMA), differential scanning calorimetry (DSC), a hot stage crystallization unit attached to a polarizing microscope and universal tensile testing machine. The TMA showed negative thermal expansion of the fiber within the full experiment temperature range. Three regions of contraction according to the values of the thermal expansion coefficient were detected. DSC analysis of both fiber and composite specimens did not reveal any appreciable difference for various thermal treatments. The tensile strength and modulus values were close to those reported for the SPECTRA - epoxy resin composite. A slight decrease of strength for the higher processing temperatures was observed while the Young modulus did not change. The study of the matrix microstructure did not give any proof of transcrystalline growth at the fiber-matrix interphase even for chemical or plasma surface treated fibers, and the matrix washed in different solvents.
A new material with impressive mechanical performance was prepared and analysed. The results of the study confirmed that HDPE could be successfully used as a inatrix with UHMPE fibres.
: i STRUCTURE CHARACTERIZATION OF LASER PROCESSED WC/Co LAYERS M. Boas*, M. Bamberger** *Rafael, P.O.Box 2250, Haifa, Israel **Material Engineering Department, Technion, Haifa, Israel
Laser surface cladding or similarly laser surface alloying can be utilized for creating a hard layer on matrix having lower hardness. This will lead to the improvement of the surface adhesive and abrasive wear properties and also corrosion resistance can be acquired to the material surface. Laser alloying hardening processes have the potential for various industrial applications with the advantage of causing lower sub-surface damage and lower dimension distortions in comparison to other hardening techniques.
In the current research, metallurgical characterization was performed to surface layers of low carbon steel alloyed with WC/Co. Laser alloying was carried out by powder injection and by melting a pre-layered plasma sprayed coating. In the two alloying methods, layers with various hardness level can be produced, depending on the working parameters of the laser beam and the alloyed material properties. Layer hardness, phases composition and the general structure depend mainly on the content of the alloying elements. Less uniform structure accompanied with surface cracks and higher hardness will result from high WC content. Lower carbides content will lead to more uniform structure with still substantial hardness. Phases composition will be mainly influenced by the laser working conditions and by the composition of the plasma sprayed which might be quite different from this of the original powder. t: MICROSTRUCTURE AND MECHANICAL PROPERTIES OF SiC PLATELET/CORDIERITE GLASS-CERAMIC COMPOSITES Rachman Chaim j Dept. of Materials Engineering, Technion-Israel Institute of Technology, Haifa, Israel Cordierite glass-ceramics reinforced by different volume fractions (0, 10,20 and 30%) of SiC platelets were fabricated by mechanical mixing of appropriate powders, followed by cold and hot-pressing above the glass transition temperature. Some of the specimen were subjected to post-sintering crystallization treatments. The resultant sintered mierostructure was highly textured within which the prismatic SiC platelets were oriented with their basal planes perpendicular to the hot-pressing direction. The true porosity was dependent upon the SiC content. The single-edge-notched-beam (SENB) fracture toughness and the bending strength increased significantly v»ith the SiC content Fractography by SEM has confirmed the crack-deflection to be a dominant mechanism which contributed to the improvement in the mechanical properties. f
SURFACE ENGINEERING OF STEELS IN MOLTEN BORAX a S. Bhagga Fazluddin*, A. Koursaris*, C. Ringas**, K. Cowie*** i •Department of Metallurgy & Materials Engineering, University of the Witwatersrand, South Africa **MATTEK, CSIR, Cottesloe, Johannesburg, South Africa ***Metal Technology Engineering, Chris Street, Alrode 1451, South Africa The formation of VC, NbC, and Cr-carbide coatings of steels immersed in molten borax baths containing carbide-forming constituents has been known for some time. A study was made of the formation of carbide coating on steel specimens treated in molten borax baths containing V2O5. The prevalence of oxidizing or reducing conditions in the bath was found to play a decisive role in the formation of the VC layer. The influence of treatment factors such as time, temperature, and bath composition on the thickness of the coating was investigated. Microstructural examination of coated specimens was performed using optical and electron microscopy. Microhardness tests, X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) analyses were carried out in order to characterise the layers produced. I ELECTRICAL RESISTIVITY OF 3104 Al-ALLOYS t A. Stern*, L. Phillips**, A.H. Cahn** | *Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel ? **National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
The most characteristic single property distinguishing metals from other materials is that of readily conducting electricity. It is not surprising, therefore, that the electrical resistivity is frequently measured and used as a tool in metallurgical research. In the application to the measurement of the temperature of 3104 aluminium sheets we utilized the temperature dependence of the electrical resistivity of the material.
The electrical resistivity of samples taken from twenty 3104 Al coils supplied by 5 manufacturers, having composition variations allowed within the alloy designation, was mesured at room and high (300°C to 400°C) temperature by the eddy current (EC) method. The room temperature EC resistivity was compared to the 4 - point probe DC measurements and a excellent agreement was found between the two methods. In our analysis of the data we have assumed the validity of Matthiessen's rule, that the resistivity of a dilute alloy is the sum of the resistivity of the pure aluminum at the specified temperature and the resistivity contribution from alloying elements and from deformation. The deformation contribution to resistivity, measured as 0.035 |i£2cm in annealing experiment, was present in the room temperature samples, and assumed absent at high temperature. The alloying contribution to resistivity (called also residual resistivity) is a function of composition and the degree of solid solution of the alloying elements. To a first approximation room temperature structure of 3104 Al alloy consists of an Al matrix having Mg, Zn and Ga in solution and Si, Fe, Cu, Ti and V out of solution in form of precipitates. Most of the Mn is out of solution in form of intermetallic precipitates and the rest is in solution in the Al matrix. The amount of the Mn in solution was calculated from the room temperature residual resistivity of the 3104 Al alloy using the values of residual resistivities per 1% weight of the different alloying elements in solution and out of solution. The calculated alloying elements in solution and out of solution. The calculated amount of Mn(%wt) in solution is in the range of 0.23 - 0.42 and different for the five manufacturers. As the amount of Mn in solution is process dependent, the different manufacturers probably used slightly different procedures to produce the coils, yielding different amounts of Mn in solution DEPOSITION OF DIAMOND FILMS ON CEMENTED CARBIDES (WC + Co) A.K. Mehlmann*. A. Fayer* and S.F. Dirnfeld*. Y. Avigal**, R. Porath*** * Department of Materials Engineering
** Solid State Institute Technion-Israel Institute of Technology, Haifa 32000, Israel ***Iscar Ltd., P.O. Box 385, Maaloth, Israel
The possibility to use diamond films on cutting tools has turned the low-pressure diamond deposition on cemented carbides into a field of large interest.
This research was performed with the aim to get quantitative estimation of the main factors which affect the diamond layer quality; nucleation density, outward diffusion of cobalt from substrate and interfacial stresses. The experiments were accomplished on cemented carbide substrate (WC + 6% Co) using the hot filament CVD method and CH4/H2 1% mixture.
The nucleation process was studied on polished and fractured surfaces. We investigated the effects of ultrasonic pretreatment and deposition temperature on nucleation. The deposition experiments performed on fractured substrates suggest that the main role in enhancing nucleation is played by surface contamination.
The SEM images of substrates surface partially covered by diamond show that cobalt particles strongly attack contiguous diamond crystals. The fact of cobalt influence diamond deposition was confirmed by the different growth kinetics of diamond coating on unetched and etched substrates. The etching was performed using a HNO3/H2O 1:1 solution.
It was found that when heating at 940°C in CH4/H2 1 % activated gas mixture a strong etching effect of cobalt, probably by atomic hydrogen, is obtained.
The residual stresses in diamond films were measured by X-rays diffraction method. The experimental results show that compression stresses take place in diamond coatings which are essentially related to deposition temperature. SOLID STATE SYNTHESIS OF CoAl AND NiAl 1NTERMETALLICS VIA HIGH jf PRESSURE CONSOLIDATION OF FINE ELEMENTAL POWDERS L. Farber and E.Y. Gutmanas
Department of Materials Engineering, Technion, Haifa, Israel
CoAl and NiAl B2 intermetallics were synthesized from consolidated to full density jj micron size elemental powder blends (Co, Ni-AI). Consolidation was performed by cold sintering (high pressure consolidation at ambient temperature) at pressures considerably lower than those required for consolidation to full density of the prealloyed intermetallic powders. Subsequent homogenization heat treatments resulted in solid state reactive ( synthesis of the corresponding aluminide. The microstructure and phase composition of the aluminides obtained were studied employing X-ray diffraction, SEM/EDS and f TEM/EDS. DTA experiments showed that at temperatures above 500°C self-propagating \ synthesis (SPS) of Co and Ni aluminides takes places accompanied by the formation of a transient liquid phase. The SPS process is difficult to control and usually results in the decreased density and cracking of the final product. To avoid the formation of the liquid : phase, the first step of the synthesis heat treatment was performed at temperatures below 500°C. During this treatment the formation of intermediate CO, Ni-AI phases of different stoichiometry, including CoAl and NiAl, was observed, the kinetics of the process being controlled by the diffusion of components through these phases. Reactive diffusion * processes in Co, Ni-AI powder systems were studied on model structures - an Al foil partly or fully embedded in a Co or Ni powder and, vice versa, a Co or Ni foil/thin sample embedded into an Al powder. Layered structures prepared from alternating thin Al and Ni foils were also used in model experiments. It was found that the synthesis process didn't go to completion at temperatures below 500°C. In order to obtain a one phase equiatomic aluminide, higher temperatures were required. The presence of the intermediate phase layers at former Co, Ni-AI powder particle interfaces allowed to accomplish the synthesis without the liquid phase formation. The described approach to •*. the synthesis of CoAl and NiAl may be used for production of close to net shape full } density intennetallic parts. »
f THERMODYNAMIC CONSIDERATION FOR SOLID STATE AMORPHIZATION BY MECHANICAL ALLOYING Y. Chakk, S. Berger, B.Z. Weiss
Dept. of Materials Engineering, Technion, Israel Institute of Technology, Haifa, Israel
Mechanical alloying (MA) is a high energy ball milling process. Powder particles trapped between the colliding balls undergo micros true tural, compositional, and surface morphology changes. Mechanical alloying is a solid state process which can lead to various results such as amorphization of crystalline alloys, formation of intermetallic compounds, creation of solid solutions from non-soluble elements, and reducing the grain size to a nano-meter scale. The final product of mechanically alloyed powders depends on the initial composition, microstructure.atomic size, and electronegativity.
In the present paper, a quantitative approach for determining the possibility of solid state amorphization of bi-elemental system by MA is presented. The model is based on known physical properties of the powder elements. This approach takes into considerations the initial lattices and atomic sizes of the powder elements, their heat of mixing, and the milling parameters. It gives the composition range where amorphization can occure for specific milling parameters and the enthalpy change associated with it. This theoretical approach was tested on various experimental data and the result will be discussed. FACTORS AFFECTING THE QUALITY OF ELECTRON BEAM (EB) WELDS OF Al 1050 END CAPS TO Al 6061 TUBES A. Stern*- **, I. Dahan* and D. Eliezer**
•Nuclear Research Center-Negev, Beer-Sheva, Israel **Materials Engineering Department, Ben Gurion University, Beer-Sheva, Israel
An experimental study on automatic and autogeneous electron beam welding (EBW) of Al 1050 and caps to Al 6061 tubes (OD 10mm x lmm wall thickness), was carried out. The composition of the bulk weld metal in dissimilar metal EB autogeneous butt welds depends on the location of the beam axis in relation to the plane of joint faces. The effect of varying the compositions of the fusion zone as a result of different EB positions (i.e. the weld metal dilution) on microstructure, discontinuities and hardness of the weld joint has been studied. Two sets of specimens, using 10 J/mm and 19 J/mm heat inputs have been welded. In order to examine the role of the dilution on the properties of the weld joint, transverse sections through the fusion zone and the HAZ were prepared for metallographic observations under optical and scanning electron microscopes. Electron probe microanalysis (EMPA) was used to determine the chemical composition of the weld metal. Microhardness measurements, carried out at a load of 0.2 N, were used to study the mechanical response of the joint to the welding parameters.
In this study, the following conclusions were drawn:
1. The most frequent weld discontinuities found in the fusion zone are porosity and cracks. The extent of cracking and porosity was correlated to the dilution of the weld metal, which in turn is influenced by the symmetry of the fusion zone.
2. A general increase in cracking and porosity occurrence was observed in the welded specimens subjected to the higher heat input.
3. The hardness profiles of the fusion zone are directly related to the degree of dilution. A significant increase in microhardness was observed in areas adjacent to fusion zone line in the Al 6061 HAZ (above 100 HV, as compared with about 60 HV in the weld metal and 80 HV for the Al 6061 tube). This result can be explained in terms of recrystallization and precipitation reactions in the HAZ of the Al 6061 tubes. HOMOGENIZATION OF LAYERED THIN FILMS UNDER ELECTRIC CURRENT L. Klinger, A. Katsman, A. Levin Department of Materials Engineering, Technion Israel Institute of Technology, Haifa
Layered thin film structures are an essential element of modern devices in microelectronics. An indispensable requirement with regard to these elements is stability in electric and temperature fields. At the operating temperatures of layered thin films, grain boundary diffusion occurs within each layer and between layers. Under the action of electric current via the multilayer film, internal stresses are fomied in conductor layers as a result of electromigration. The stresses that appear in adjoining layers are responses. The stress gradient across the layered structure intensifies the interdiffusion between layers which, in turn, accelerates homogenization of the layered structure.
In the present work we consider internal stress formation in a two-layer thin film on an undeformed substrate under the action of electric current. Layer conductivities are assumed to differ substantially. Stress relaxation may lead to growth of hillocks at the outer surface. Where a conductor does not possess an outer surface, relaxation occurs by interdiffusion - mutual penetration of material from one layer to another.
Diffusion equations describing the process were solved, taking into account the fluxes of components caused by stress gradients formed during diffusion and also the process of stress relaxation.
Stress distribution, constituent concentrations and their time dependencies were calculated for a two-layered thin film structure. The velocity of the cathode edge as a function of path length, current density and temperature was studied. The calculated * MAGNETRON-SPUTTERED Co-DEPOSITED THIN nLMS AS A METHOD FOR < f CONSTRUCTION OF MULTI-COMPONENT PHASE SYSTEMS I. Goldfarb and D. Shechtman
• Technion-Israel Institute of Technology, Haifa 32000, Israel
The preparation of a series of alloy specimens that follow a full binary or ternary ' composition range is a difficult task if bulk specimens are made in large numbers.
In our method we prepare a continuous sample covering all composition range of a multi- component systems, with the desired composition accuracy. Our method involves ' prismatically (Wedge-shaped) deposited alternating thin multi-layers of the desired components in such a manner that the concentration gradient will be from 0% to 100% for • each component. ] In this study, the Au-Ag-Cu ternary system was chosen for its simplicity and application. This diagram is characterized by phase separation resulting from the binary Ag-Cu diagram, and by ordering reactions from the binary Au-Cu systems. Unlimited solubility in all composition range takes place in the binary Au-Ag system. 30 tri-layered films, 12 nm each, were sputter-deposited in 55 Formvar-coated Mo grids. The overall thickness was chosen to be thick enough for X-ray diffraction (XRD) and for suitable Energy Dispersive Spectroscopy (EDS) analysis, but thin enough for Transmission Electron Microscope (TEM). Mo was chosen as a substrate material for its inertness to Au, Ag and Cu in the relevant temperature range. The substrate grids were arranged in a form of close-packed triangle so as to give 55 differently-composed samples, covering an isothermal section through the ternary phase diagram.
The investigation was proceeded in following stages:
1. Samples were deposited by means of magnetron DC-sputtering onto the substrates at room-temperature, as described. \ i • 2. The as-deposited samples were analyzed by XRD and EDS, in order to determine their structure and composition. ,,
3. Samples were then homogenized by heat-treatment at low temperatures for various periods of time, resulting in multi-phased equilibrium samples.
4. These samples were then analyzed again by XRD, and by TEM.
Based on these results, it is concluded, that the proposed method is an effective way for a ,,h construction of multi-component phase systems, }
.4.2 ELASTIC INTERACTION BETWEEN PRECIPITATES IN THIN LAYERS
R. Shneck*, M.P. Dariel* and A. Brokman** *Ben Gurion University of the Negev, Beer Sheva, Israel **Jerusalem, Israel
Our work is concerned with the effect of the elastic interactions on the precipitate distribution within thin films. We shall present and discuss the solution of the elasticity problem of a finite coherent precipitate in an elastic, isotropic and homogeneous layer. It is well established that the elastic interaction between dilating precipitates vanishes in a isotropic infinite matrix. The proximity of free surfaces induces, however, an attractive elastic interaction between like particles that increases monotonically with decreasing interparticle distance. The attractive interaction is maximal when the particles become of equal size and it increases as they grow closer to the free surfaces.
The correlations that result from the elastic interaction in the thin layers generate a tendency towards clustering of equal-sized particles. However, the self-energy of an isolated precipitate decreases rapidly as it grows closer to the free surfaces favoring,at the advanced stages of the precipitation, precipitate coalescence rather than clustering.
1 .4.3 GRAIN GROWTH IN COPPER-CHROMIUM MULTILAYERS
' U. Admon*. M.P. Dariel*- **, G. Kimmel*, J. Sariel*, A. Stechman*- ** and I L. Zevin** *Nuclear Research Centre-Negev, POB. 9001, Beer Sheva, Israel **Deparunent of Materials Engineering, Ben Gurion University, Beer Sheva, Israel
Copper-chromium multilayers with wavelength, k ~ 20 nm, were prepared by dual magnetron sputtering on silicon substrates. The mutual immiscibility of copper and chromium ensures that the layers retain their individual character and that no interdiffusion or reaction takes place between them at the deposition temperature. Low-angle X-ray diffraction revealed a well defined one-dimensional copper-chromium superlattice and -* allowed the accurate determination of the repeat distance, namely the combined thickness of two adjacent layers. ,
High-an<:!c X-ray patterns showed the presence of a intense but broadened (111) Cu line, suggesting a strongly textured layered structure. The absence of Cr diffraction peaks, in spite of the presence of 30 % Cr, as indicated by EDS measurements, is attributed to the nature of the chromium layers, a relatively high melting point metal. At the deposition temperature, the Cr layers are either amorphous or nanocrystalline.
High temperature X-ray diffraction runs were carried out in the 300-620°C temperature range, as a function of the length of the dwell time at the high temperature. The height of the (111) Cu diffraction line increases with its concurrent narrowing, while the integrated intensity stays relatively constant. The narrowing of the diffraction line is due to the grain growth taking place in the copper layers during the high temperature anneal. The analysis of the line narrowing as a function of the annealing time provides information regarding the kinetics of grain growth within the multilayers. In principle, results obtained at different temperatures allow to infer in the mechanism of copper mobility within the multilayers, in particular, regarding the relative contribution of the bulk, grain boundary • and surface diffusion effects.
Additional peak appear above 600°C. Preliminary interpretation suggests the nucleation 5 of chromium or chromium rich compounds. Additional experiments are underway to determine the temperature range for chromium nucleation and grain growth within the multilayered material.
The results establish the potential and scope of using multilayered metallic materials as subject of study of nucleation and growth phenomena in thin metallic layers. f "
t. 4.4 I ELECTROMIGRATION IN THIN FILMS: TIME DEPENDENCE OF STRESS I DISTRIBUTION AND HILLOCK GROWTH f A. Katsman, L. Klinger, A. Levin, E. Glickman
| Dept. of Materials Engineering, Technion, Israel Institute of Technology, Haifa, Israel
^ This study is devoted to stress initiation and evolution due to electromigration in thin films. The new element of the proposed analysis is explicit inclusion of the relaxation process occurring through formation of hillocks near the anode end of the conductor line under consideration. Calculation is based on Kirchheim's model in conjunction with the creep equation which controls the rate of hillock formation.
Two cases are analyzed: (i) extrusion of material through a fixed aperture (e.g. in dielectric coating); (ii) extrusion through an aperture whose size is time-dependent; in this case the hillock zone size is a function of the stress distribution. It was shown that after a short incubation period, the stress distribution can be calculated via a diffusion-like equation with a source: fO, 0 aa ~((E/n)(CT-at), 0>at where Da = D Q E/kT is the effective diffusion coefficient (E - modulus of elasticity, T) - effective viscosity, 1.4.5 CERAMIC MATRIX COMPOSITES PRODUCED BY DIRECT MELT OXIDATION E. Manor*, H. Ni**, C.G. Levi**, and R. Mehrabian*** *Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel **Materials Department, University of California-Santa Barbara, Santa Barbara, CA 93106, U.S.A. ***President, Carnegie Mellon University Pittsburg, PA 15213, U.S.A. Ceramic Matrix Composites produced by direct melt oxidation can be designed to have high toughness and good thermal shock resistance, as well as high stiffness, good wear resistance and high temperature stability. Furthermore, the method allows production of near net shape at a low cost. In the more general case, the high temperature oxidation (T > 1200°K) of molten Aluminum with suitable alloying additions yield a continuous AI2O3 matrix with interpenetrating three dimensional network of metal microchannels. Favorable structure properties can be achieved by growing this "composite-matrix" into preforms consisting of reinforcing particulates. Characterization of the resulting composites included the volume fraction of SiC and residual metal, the scale of the microstructural features, the composition of the metal within the channels, and the porosity as a function of both temperature and SiC particle size. The oxidation rate of a slightly modified A380 Aluminum alloy was significantly enhanced by the presence of the SiC preform, with a tendency to increase with decreasing particle size. The underlying mechanism involves: preform wetting and secondary nucleation of AI2O3 on the particle surfaces, perhaps by reaction of the alloy with the S1O2 layer formed on the SiC. The study was initiated with the objective of enhancing our understanding of the growth of an Al2C<3/metal matrix into SiC preforms, evaluating the role of the preform on the growth process and the origin of various microstructural defects, notably porosity and chemical segregation. I TENSILE BEHAVIOR OF ALUMINA CARBON/EPOXY LAMINATED SYSTEM | Dov Sherman and Frederick A. Leckie Department of Mechanical Engineering, University of California, *' Santa Barbara, CA 93206 }• Ceramics are attractive due to their superior mechanical properties. The elastic modulus of ceramics is high, and the density is low. As a consequence, the specific modulus (E/p) and strength ( An alternative system is reported hete The composite is made of a multimaterial laminated system consisting of alternating together brittle and ductile thin layers. The britlle, the ceramics, is stiff and the ductile is stronger and has later strain to failure, and serves as the reinforcement. This system is a new philosophy in reinforcement of brittle materials. A thin alumina layers, alternating together with carbon/epoxy prepreg tapes.represents a brittle ductile laminated system. This system is available for experimental study, is cheap and can easily be obtained. It gives an excellent oppohinity to study the mechanical behavior of brittle ductile laminated systems, and is a first step in investigatirehigh "* ( ^performance ceramics. Experimental studies of alumina carbon/epoxy reveal the potential of this type of reinforcement. It is observed that the stress for first cracking in this system is much larger than for embedded fiber reinforced brittle matrix composites. Another advantage of such layered systerrys that the undamaged modulus and strength are nearly isotropic that is significant when the material is subjected to biaxial stress state. In addition, multiple fracture mechanism when loaded in the carbon fiber direction causes pseudo ductile behavior of the system. The mechanical behavior in tension is fully described. The influence of number of layers is examined experimentally and minimum number of layers is set for maximum stress for first fracture. Highly branched wide laminated system are compared with narrow system to demonstrate the width effect in such laminates. 1/ PROCESSING OF AI2O3 - SiC POWDER 'NANOCOMPOSUES" I. Levin and D.G. Brandon Dept. of Materials Engineering, Technion-Israel Institute of Technology, Haifa, Israel The mechanical properties of alumina based ceramics can be enhanced by the addition of a small volume fraction of submicron SiC particles. The conventional method for producing a such material is by hot-pressing. The purpose of the present work is to develop pressureless sintering for high-density alumina with small additions of submicron SiC particles dispersed in a high-purity matrix. Green compacts were processed by attrition milling of the initial powders followed by filter-pressing. Optimization of the processing parameters was designed to obtain green compacts with high packing density. Introduction of SiC submicron particles as a wear product of SiC grinding media during attrition of the alumina powder was investigated. XRD quantitative analysis was used to determine the SiC content. Information about size of the SiC particles and their distribution in the matrix was obtained by EDS mapping. The influence of processing parameters on the green density of compacts will be discussed. 2.1.3 GLASS-CERAMICS: OPTIMIZATION OF STRUCTURE, PROPERTIES AND TECHNOLOGY Rimma Khodakovskaya IMI (TAMI) Institute for Research & Development Ltd Glass-ceramics are obtained by the method of nucleated crystallization of glass. We have investigated the regularities of this process including the kinetics and mechanisms of phase separation of glass, phase transitions during its crystallization and relationship between structure and properties of glass-ceramics. With this aim we used different structural methods such as XRD, SAXS, TEM, EPR, IRS, Neutronography, DTA, DTG etc. for the experimental study of the process and materials. The specific objects of our research were glass-ceramics based on cordierite, mullite, quartz-like solid solutions (MgO-Al2O3-SiO2 system) and (J-eucriptite and (i-spodumene solid solutions (Li2O-Al2O3-SiO2 system). The effects of the main factors controlling the process, namely: temperature and redox conditions of glass melting, regime of crystallization, pre-crystallization heat-treatment, small additives of extraneous oxides, concentration of nucleating agents were elucidated and as a result, methods for optimization of structure, properties and technology of glass- ceramics were established. The features of the crystallization and sintering of glass powders and their mixtures with crystal were elucidated. As result we could broaden the range of glass-ceramics compositions, using ones outside the glass-forming ranges, by applying powder (ceramic) technology. We propose a novel principle of formation of glass-crystalline structures by self-heating reactions, which take place during the sintering of powders with special additives. We have applied this principle for obtaining mullite glass-ceramics and also high-temperature coatings. A large group of glass-ceramics with valuable properties was thus developed, based on both glass and ceramic technology. These materials are characterized by high strength (up to 6(X) MPA after thermal-chemical strengthening), thermal expansion coefficient over a wide range of values (from 100-10"7 K"1 to 200-10"7 K-1, among them materials with a near to zero), high thermal shock and chemical resistance, low dielectrical losses (< 5-10"4), dielectrical constants of 5-25, controlled porosity, bioactivity. ?. 1 .4 MICROSTRUCTURAL AUDITING TO TRACEABLE STANDARDS IN THE PC DRIVEN QUALITY CONTROL LABORATORY Brian Bousfield Technical Marketing Manager, Buehler Europe Ltd., Coventry, England ABSTRACT Total information management throughout all aspects of a manufacturing process, from user material through production and sales, can best be managed via some form of file server acting as a director of operations. The quality control laboratory although operating with individual computers will inevitably be linked to the file server. The implications of this and the opportunity it affords to update our thinking in the subjective black art of surface preparation for microstructural analysis will be investigated. SITUATION Microstructural analysis is subjective, the surface preparation method or recipe is often the result of a committee driven "round robin", the results being empirically derived, the emphasis on machine automation without control being fraught with pitfalls. There are no standards, no statistical means of auditing and the results are not traceable. Finally and perhaps in consequence there exists no formalised training programme for technicians specifically involved in surface preparation of materials. This paper therefore will address these problems and will use as an example the work carried out on a recent European vocational training course held in the UK (Dec. 1992). The subject of the course was "Auditing to Traceable Standards - Plasma Spray Coatings". Integrated within this work will be the logistics of the PC driven quality control for total information management. c THE EFFECT OF TRAPPING AND RELEASE PROCESS ON THERMONUCLEAR FUSION REACTORS PERFORMANCE E. Abramov Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel and Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel Trapping and release processes occur during the operation of thermonuclear fusion reactor are reviewed. A theoretical study have been conducted to quantify trapping parameters under the relevant conditions. The results show that large quantity of hydrogen isotopes atoms will be accomodated in trapping sites at relatively high binding energy. This will drastically affect the fuel, i.e. hydrogen isotopes, balance. A large scale experimental study was carried out in order to verify the theoretical findings. Hydrogen trapping and release parameters have been measured over wide range of helium pre-implanted samples. These samples represented the materials which will behave as the first wall of fusion reactor after different aging duration. An unexpected phenomenon of enhanced helium release due to hydrogen introduction was observed. This behaviour will damage the plasma purity and therefore the reactor performance might be affected. 1 ? . ? . 2 IM BMTERFACIAL EFFECTS IN THE PRESENCE OF HYDROGEN IN Al / AI3T1 / SiC G. Solovioff and D. Eliezer Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel Dispersion strengthened, elevated temperature aluminium-titanium alloys derive their strength and thermal stability from the presence of dispersed nanometer-size particulates which effectively impede dislocation motion during deformation. The strengthening characteristics of these particulates at elevated temperatures are dependent on their ability to resist coarsening. Among the family of transition metal, high temperature alloys, Al-Ti alloys are actively being studied due to their attractive combination of elevated temperature properties. In addition, AL-Ti alloys are being studied as potential candidate matrix materials in metal matrix composites (MMCs) in an effort to further increase the modulus and the strength. There is definitive proof that hydrogen can interact with any number of features commonly found in most structural alloys, including point defects, dislocations, grain boundaries, particles and voids. In the present study, spray atomized and co-deposited Al/Al3Ti/SiC were characterised following hydrogen charging, in order to investigate the effects on microstructure and in the Matrix-Particles interface. The cooperative relation between microscopic distribution of hydrogen and fracture morphologies will be discussed. it 2.2. 3 I* A NEW MATHEMATICAL APPROACH BASED ON THE CIRCULAR DIAPHRAGM TO EXPLAIN THE BLISTER EFFECT ON IMPLANTED METALS D. Moreno*, E. Abramov* and D. Eliezer** *NRCN, Beer Sheva, Israel **Dept. of Materials Engineering, Ben Gurion University , Beer Sheva, Israel The deformation and partial exfoliation of surface layers due to hydrogen and/or helium interaction with metals has been the subject of considerable research. Blister formation due to the build-up of induced gas into the metal was investigated widely in diverse metals and alloys. However there is no consensus as to the driving mechanism behind this phenomenon. Recently, a new approach on the blister formation phenomenon has been discussed by means of the mathematical solution on a uniformly loaded circular plate with clamped edges (circular diaphragm). It is general accepted that the blister formation depends strongly on the metal/alloy surface temperature, crystallographic orientation and on the energy and dose of implantation. In the present investigation we found that the blister formation depends on the mechanical properties of the material and the near surface concentration of the implanted gas, which depends on the crystallographic orientation by means of the stopping power of the implanted atom. We assume that both the mechanical properties and the penetration of the bombarded atoms depends strongly on the temperature of implantation. In order to obtain diverse depths and concentrations of gas, based on the Pearson IV, helium was implanted at different energies and doses at the same temperature. The irradiation was carried out using the MEIRA (The Soreq high output isotope separator- Israel). Sample groups of, 1) annealed copper polycrystal, 2) single crystal in the principal directions <001>, <101> and <111>, and 3) Cu-2 Be-o.2 Co after diverse thermomechanical treatment in order to obtain mechanical properties, had been implanted at a specific dose among 2xlO17 - 2.3xlO18 He/cm2. The depth profile was analysed by secondary ions mass-spectrometer (SIMs). The surface morphology was analysed using a scanning electron microscope (SEM). Representative histograms of the blister size distribution were carried out, based on a large number of micro graphs. In almost all models, blister initiation starts from the assumption of excessive growth of large gas bubbles either by the agglomeration of clusters or by the coalescence of small bubbles. Growth of large gas bubbles causes the transport of residual interstitial atoms by dislocation loop glide toward the surface. The atom movement becomes possible because helium and vacancies coalesce in bubbles and tend to build-up large cavities parallel to the surface. The reported model is based on the fact that at certain depths from the surface the pressure in the cavities approaches the yield stress of the metal and blistering will start. The thickness of this Film depends on the mechanical properties of the specific metal. Once the blister cavity is formed, the deformation of the thin film to form a blister cap on the build up of the pressure in the cavity which depends on the implanted dose. The present model can be concluded by saying that the thickness of the blister's cap cannot be correlated with the projected range of the implantation as assumed by other authors elsewhere. The helium concentration needed to build up a pressure to create blister in a depth which is close to the projected range is higher than the implanted concentration and the edge of the circular skin where the maximum stresses are developed and the fact that at high implantation energy (large projected range) the bursting of the blisters occurs by multi layer caps support the present model. 2.2.4 HYDROGEN EFFECT IN INTERMETALLIC TITANIUM - ALUMINIDES ALLOYS I J. Haddad, D. Eliezer Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel The titanium aluminides basically are of two generic types: the ordered hexagonal close packed Ti3Al (012) and the ordered face centered tetragonal TiAl (y). The low density ordered intermetallic titanium aluminides, based on Ti3AI and TiAl have drawn a lot of research attention mainly due to their favourable elevated temperature properties. Because of their ordered crystal structures both families of alloys have very attractive elevated temperature strength characteristics but their Achilles heel is low ambient temperature ductility. Ternary alloying has overcome the problem of low temperature brittleness of both alloys. Niobium additions improve the ductility of alpha-2, and the ductility of gamma is improved by vanadium additions. Hydrogen embrittlement of titanium alloys, although most often associated with a single form of degradation (hydride formation) can be very complex, and very little understanding presently exists of the hydrogen interaction with the titanium-aluminide phases. Understanding of ductility and fracture behaviour is still emerging, as is knowledge of environmental effects such as hydrogen embrittlement This study investigated the effect of hydrogen charging on the phase changes and the hydride formation at room temperature on Ti-48Al-lV at.% (Ti-48-1), and on Ti-25Al-10Nb-3V-lMo at.% alloys. 2.2.5 f I i EXTREMELY SMALL CRYSTALS IN MULTI LAYERED C.V.D COATING OF TiC + TIN AND THEIR EFFECT ON THE PERFORMANCE OF CUTTING TOOLS Reuven Porat, Natalie Arishkevitch, Avi Geltz ISCAR LTD., Tefen, Israel In the process of coating it is known that one of the useful combinations for coating cutting tools is to use a triple layer of TiC + TiCN + TiN. This combination gives combined wear protection. TiC is a good adhesive wear resistant which protects the cutting tool from flank wear and TiN is a diffusion barrier wear resistant which protects the cutting tool from crater wear. While we increased the number of coating layers to achieve the same coating thickness we got the advantage of higher tool life in machining steels. However, aside from having higher wear resistance, using this combination also helps us to increase efficiency of the machining process by increasing the cutting speed. The explanation for this advantage of wear resistance and the capability to withstand high cutting speeds can be explained by the multi layer interruptions, as these interruptions of the wear mechanism cause a halt in the wear procedure. This multi coating layer can reduce and even neglect the effect of the substrate properties on the behavior of the coating, i.e., this combination is the best barrier diffusion for cobalt and carbon from the substrate to the coating, so the properties of the coating are unaffected by the properties of the cemented carbide substrate. Another advantage is that while in single layers, increasing the thickness of the coating causes a reduction of the good mechanical properties, such as transverse rupture strength, and increases the sensitivity for fractures. In this case, the multi layer coating behaved like a stopping mechanism to eliminate propagation of the cracks, so that the thick coating behaved like a thin coating enabling all the mechanical properties of the substrate to remain with only small reductions in the mechanical properties. By using multi layers we can increase the rate of deposition. In the beginning of every coating process the rate of deposition is extremely high, after which gradually reaches a much slower pace. By starting each layer from the beginning, and having higher amounts of layers, we succeed to increase the deposition rate, and achieve greater efficiency in the crystal growth rate. In this paper we represent tool life of C.V.D. coated cutting tools, in machining steel with different cutting speeds and comparison between coated cutting tools with multi coated layers, to single layers. 2.3. ELECTROCHEMICAL DEPOSITION OF ALLOYS OF GRADUATE COMPOSITION Fe/Cu R. Interter and Yoseph Yahalom Compositionally modulated alloys exhibit greatly altered properties relative to the pure component of their homogeneous alloys. The mechanical and magnetic properties of these alloys are of particular interest. These properties are highly dependent on the individual layer thickness of the composite. These alloys have been usually deposited by vapor deposition or by ion sputtering. A system of special interest is Fe/Cu since iron and copper do not dissolve in each other at the ambient temperature. If each component should preserve it's structure a clear interface boundary would be expected between the layers. It was the purpose of the present work to develope a method that would produce foils of modulated Fe/Cu alloys by electrodeposition. The procedure used was based on the Yahalom Zadok method for deposition CM A by electrochemical means. By this process an ordered alloy of two metals in alternated layers is built. This process uses a pulse plating technique in which the less noble metal is plated at a lower potential followed by a step in potential to the deposition value of the nobler metal layer. The deposition of the two metals is done from the same solution while the more noble metal is in a low concentration compared to the less noble metal in order to limit by diffusion it's deposition during the deposition of the more active metal. By repetition of this process the compositional modulated layer is formed. Deposition of modulated structure of Fe/Cu by square pulse is problematic. However the iron layer dissolves when the potential is switched from the deposition potential of iron to that of copper. Means to overcome this difficulty have been developed in the present study. An electrolyte containing an inhibitor for iron dissolution was used. More importantly the gradual pulse technique was used for formation of Fe/Cu compositionally modulated alloys. X-Ray diffraction of a deposit with 100 A layers confirmed the presence of iron in the sample in BCC structure. Auger analysis of CMA with designed 100 a layers indicated that iron is present at an average concentration of about 10% indicating a low current efficiency for iron deposition under the pulsing conditions. The modular structure of the Fe/Cu layers cannot of course be revealed in the Auger profile since it is below the resolution of the instrument. 2.3.2 THE INFLUENCE OF A THIRD ELEMENT ON THE INTERFACE RACTIONS IN METAL MATRIX COMPOSITES (MMQ: Al - GRAPHITE SYSTEM D. Lotker*, J. Pelleg*, D. Fuks*,M. Ganor**, O. Yeheskel** •Department of Material Engineering, Ben Gurion University of the Negev, Beer Sheva, IsraeJ **Nuclear Research Center, Negev, Beer Sheva, Israel First principal calculations have indicated that reaction between fiber and metal matrix can be reduced to a large extent, or even eliminated when appropriate solute in small quantities is incorporated in the MMC. In the Al-graphite (gr) composite system interface reactions were observed by different researches, when such an MMC is maintained at sufficiently high temperatures. Such reactions may occur either during the preparation of such composites or during thermal treatment. We have produced Al-gr specimens by infiltration by molten Al under pressure in graphite molds at a temperature of 775°C. Silicon at a level of 0.5% was used as the addition to reduce the reactions at the fiber-metal interface. Control specimens without silicon were also prepared. The specimens were characterized at all stages by X-ray diffraction to see if AI4C3, which is the reaction product, was formed in the above system. No presence of AI4C3 was found in the specimens with the silicon addition, where's appreciable amounts of this phase were found in the control specimens. The results of the metallographic examination by SEM and optical microscope will be discussed. The kinetics of reaction zone formation in this type of specimens will be presented. 2.3.3 DIAMOND-LIKE CARBON FILMS: PREPARATION, MICROSTRUCTURE - PROPERTY RELATIONSHIP A. Raven*, L. Martinu**, J.E. Klemberg-Sapieha**, and MR. Wertheimer** *NRC-Negev, Division of Chemistry, P.O. Box 9001, Beer Sheva 84190, Israel **"Groupe des Couches Minces" (GCM) and Department of Engineering Physics, Escole Polytechnique, Box 6079, Station "A", Montreal, Quebec H3C 3A7, Canada Despite great interest in deposition of crystalline diamond, diamond-like carbon (DLC) films are also considerably important. The main reason for this is the possibility of preparing homogeneous, dense, chemically inert films with low friction coefficient, at low substrate temperature (below 200°C) and over large areas. Deposition of DLC from hydrocarbon fed gases in low pressure glow discharge has become a widely used method of preparation. During growth, the layers are subjected to ion bombardment, controlled by the difference between the plasma potential and the negative dc bias voltage at the sample surface. The resulting dense films are usually characterised by a sp2/sp3 hybridization ration of ~0.4, by hydrogen concentration in the range 20-40 at.%, optical gap 0.8-1.5 eV, refractive index 1.9-2.2 and density 1.5-1.8 g/cm3 (1-3]. Based on the comparison of hydrogen concentration values determined by the nuclear elastic recoil detection (ERD) technique with infrared spectroscopy data, microhardness and density measurements, it was found that the DLC films can be distinguish to three different microstructural categories [1], namely: (a) hard hydrocarbon, with hydrogen predominantly unbonded, which is typically deposited under high (> 200 eV) ion energy, but lower ion flux; (b) hard hydrocarbon, with hydrogen predominantly bonded, this material being deposited under high ion flux, but low (~ 100 eV) ion energy, and (c) a mixture of hard hydrocarbon and polymer-like component, grown under high ion flux but low ion energy (< 20 eV). The current investigation in deposition of DLC films has been motivated in order to correlate between processing, microstructure and properties (microhardness, density, adhesion, friction coefficient), and to develop some understanding regarding those issues. 1. A. Raven, L. Martinu, S.C. Gujrathi, J.E. Klemberg-Sapieha, and M.R. Wertheimer, Surface and Coatings Technology (in press). 2. L. Martinu, A. Raveh, A. Domingue, L. Bertrand, J.E. Klemberg-Sapieha, S.C. Gujrathi, and M.R. Wertheimer, Thin Solid Films 208, (1992) 42. 3. A. Raveh, L. Martinu, J.E. Klemberg-Sapieha, and M.R. Wertheimer, J. Vac. Sci. Techno!. A 10. (1992) 12. 2.3.4 PATTERNING OF SUPERCONDUCTING YBCO FILMS M. Riabkina-Fishman, J. Zahavi Israel Institute of Metals, Technion, Haifa 32000 Development of lithographic techniques for patterning YBCO superconducting films to the required configuration would represent an important technological achievement that would allow the incorporation of this type of superconductors in microelectronic devices. The necessary patterning precision could be achieved by conventional litography techniques used in microelectronics industry, but the wet treatment involved in lithography methods is detrimental to the conductivity of TBCO films and therefore this approach is not optimal. There is a different approach to the patterning of YBCO films. This approach takes an advantage of the fact that superconducting properties of YBCO films are a function of the substrate type and that only an epitaxial growth producing oriented YBCO films with Cu-O planes parallel to the substrate surface will result in superconducting film with a high critical temperature. The principle is to use a substrate which is known to favor epitaxial oriented growth of YBCO film and deposit on it an amorphous or polycrystalline layer. Then this layer must be processes by an appropriate precision lithography technique in order to expose areas of substrate in the desired shape and size. At the third stage YBCO film is deposited on this processed substrate. The deposited YBCO film, while covering the whole surface of such a composite substrate, would possess superconductivity only in the areas where original substrate was exposed prior to YBCO deposition and would be insulating where the intermediate layer was preserved. SrTiO3 (100) single crystals were used as a substrate and amorphous SiO2 films 2000 A thick were deposited as an intermediate layer. The results of resistivity measurements on patterned and unpatterned films showed that the patterned film had only slightly lower onset anil critical temperatures (Tc = 88°K instead of 90°K). AMORPHOUS DIAMOND-LIKE-CARBON FOR MIS ANS MIM DIODES M. Alaluf, D. Aizenman and N. Croitoru Department of Electrical Engineering-Physical Electronics, Tel Aviv University, Israel Amorphous Diamond-Like-Carbon (DLC) films were deposited by r.f. plasma system in methane (CH4) environment. The amorphous film was found to have a diamond structure (TEM micrograph) with hardness of 4800 knoop. It was found that the film is semiconducting with an energy gap of 2.7 eV, a typical resistivity of 108 Qcm and measured optical transparency in the visible and mid-IR light. Rectifying Al/DLC/p-type silicon and A17DLC/A1 diodes were fabricated. Electrical measurements of current- voltage (I - V), capacitance-voltage (C - V) characteristics and the temperature dependence of the current (I - T) were measured. The I - V and the I - T measurements shows two conducting processes: a) ohmic dependence at low electric field (E < 1.2 x 104 V/cm) and b) Frenkel-Poole emission type with low barrier height (<|>m = 0.37 - 0.44 eV) at high electric field (E > 1.2 x 104 V/cm). These processes are typical behavior for Metal- Insulator-Semiconductor (MIS) and Metal-Insulator-Metal (MIM) diodes. r f 2.4.J I BARIUM NONATITANATE DIELECTRIC MINIATURE RESONATORS FOR I MICROWAVE CIRCUITS ? Goldstein A., Kravchik M., Stancovsky V., Belov V. /. Israel Ceramic and Silicate Institute t -; Technion City, Haifa, 32000 Ceramic materials with intermediary constant values offer the possibility to produce millimeter size resonators of high quality. The low size compared to that of the traditional Invar alloy cavity resonators makes the ceramic resonator a natural choice for a variety of electronic systems operating in the gigahertz frequency region, mostly for applications related to tele-communications. Materials having compositions located in the titania-rich region in the BaO-TiO2 system were shown to possess the properties required for the production of high quality resonators. The relevant parameters are the dielectric constant e, the quality factor Q, and the temperature coefficient of resonance frequency TC. Their values are determined by the phase composition, microstructure, nature and amount of impurities. The objective of this investigation was to determine the technology enabling one to obtain resonators with optimal dielectric properties. Various powder preparation and processing methods, green body formation techniques, thermal treatment schedules and the influence of dopants like Sn and Mn were examined and correlated. The phase and chemical composition and the sintered specimens' microstructure were investigated too. The values of £ and tg5 (Q) were measured at 1 and 10 MHz (preliminary testing). Specimens with a bulk density close to the theoretical value, containing only dibarium nonatitanate phase were obtained. Those specimens exhibited values of e about 40 and of tg5 less than 2 x 10"4. Resonators based on this material are presently being tested. 2.4.4 CORRELATION BETWEEN ELECTRICAL PROPERTIES AND STRUCTURAL CHANGES IN Sb IMPLANTED SiixGex LAYERS Z. Atzmon*, M. Eizenberg*. J.W. Mayer**, Y. Shacham-Diamand**, F. Schaffler*** *Dept. of Mat. Eng. and Solid State Inst., Technion, Haifa 32000, Israel. **CornelI University, Ithaca, NY 14853, USA. ***Daimler-Benz AG, Ulm Research Center, D-7900 Ulm, Germany. Electrical properties of Sb implanted strained Si/-xGex alloy layers are reported. Two sets of Sii-xGex epilayers with compositions of x = 0.08 and 0.18, MBE grown on (100) Si substrates, were implanted at room temperature with Sb+ ions at energies of 200 and 100 keV, respectively, and doses of 1013 and 1015 cm-2. These alloys were heat-treated in a rapid thermal annealing (RTA) system at temperatures between 500 and 900°C for durations between 5 and 600 sec. Secondary Ion Mass Spectrometry (SIMS) and Spreading Resistance Profiling (SRP) measurements show that Sb implantation with a does below the critical value for amorphization (1013 cm"2), formed a p-type region upon annealing at 500°C. Only higher temperature anneals transformed the implanted layer into the expected n-type doping. Maximal values of electrical activity (45 ± 10%) and mobility were obtained in this case only at temperatures around 8OO-9O0°C. For the high does implantation (1015 cnr2) it was found that the highest activation efficiency was obtained at 500-600°C. The maximal electrical activity at the implantation profile peak was 50-60%, a value which is six fold larger than the maximum solid solubility of Sb in Si at the annealing temperature. However, the electrical activity in the end-of-range (EOR) region was very low, probably as a result of unannealed point defects that produced the p-type region at the low dose implantation. 2.4.5 SIMULATION OF HYDROGEN ISOTOPES DIFFUSION THROUGH METAL LATTICE CONTAINS A CONTINUOUS ENERGY TRAPS E. Abramov*- ***, N. Yakobovitch**, E. Berman*** and D. Eliezer *** *Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel **Israeli Air-Force, Tel Aviv, Israel ***Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel A unique computer code DIFFTRAP have been developed to solve diffusion equations when continuous energy traps exist. DIFFTRAP enables simulation of light atoms diffusion through metal lattice contains any known distributed traps under general initial and boundary conditions. The advantages of DIFFTRAP in comparison with other previously exist codes is described. An application of DIFFTRAP for the case of hydrogen trapping near or around helium bubbles is presented. The simulation of thermal desorption experiment using DIFFTRAP is shown. The desorption curve simulated by using continuous energy traps is compared to those resulting by using discreets energy traps. DIFFTRAP can be used to improve the estimation of hydrogen isotopes recycling between the plasma and the walls of thermo-nuclear fusion reactor. 3. 1 . J i. C SURFACE MECHANOCHEMISTRY OF CRYSTALLINE SOLIDS E. Gutman Dept. of Materials Engineering, Ben Gurion University of the Negev, Beer Sheva, Israel Interactions of crystalline solids with an environments and one with another are going through an influence of solids stress state which is named mechanochemical effect. Mechanochemical systems behave as an open nonequilibrium systems. Nonlinear synergistic effects of surface and volume interactions are likely. The structure of mechanochemical system has hierarchical, heterogeneous self-correlated type and it is controlled by the minimum entropy production principle. The following in fundamental principals of solid mechanochemistry new notions were introduced. These are mechanochemical (mechanoelectrochemical) activity of substance, chemical potential of dislocations and "dislocation lattice" in a crystal, affinity of plastic deformation process, dislocations flow. This made possible to estimate a connection between chemical potential of solid atom and dislocation, also describe kinetic equations for mechanochemical phenomena. Generally, the entropy production of the such system consists of minimum three main terms which are corresponding to three irreversible processes: deformation, chemical reaction and solid dispersion. These processes are developing, for example, during surface solid treatment, stress corrosion, solid-state synthesis, powder sintering, preparation of ultrafine-grained powders, amorphization by milling, applications of disintegratory technology, etc. In this paper the basic theoretical notions of mechanochemistry are reported as well as some of its practical applications. A new effect of metals and minerals plastification, that we called "chemomechanical effect", enables to propose methods for the mechanochemical surface treatments of metals, alloys and minerals. This effect was a theoretical phenomenon followed by experimentally proved phenomenon, as additive plastic flow of solid under chemical (electrochemical) reactions on its surface. The chemomechanical effects was displayed in mineral (calcite) single crystal dissolution by appearance of mechanical twins and their growth from microhardness indentation and in metal (iron) single crystal by the appearance of jogs of slip-band on microhardness indentation faces. For engineering materials we developed a special method for the measurement of depth penetration (hardness) of a needle-shaped indentor into surface that is polarized from the potentiostat. The determination of chemomechanical effect allows the evaluation of the role of the autocatalytic mechanism of fracture for the control of chemical resistance, and the development of new material treatment technologies (as wet-drawing, mechanochemical cleaning of metals, grinding and dispersion of minerals, drilling, etc.). f. NONISOTHERMAL EFFECTS DURING THE MAES CRACK PROPAGATION IN I BRTTTLE MATERIALS i % E. Druinsky*, L. Levin*, R. Arone**, A. Klyuch* i ? *Department of Materials Engineering, Technion, Israel Institute of Technology, Haifa ; 32000, Israel **Israel Institute of Metals, Technion, Israel Institute of Technology, Haifa 32000, Israel The classical criterion for a brittle fracture of solids is given by the Griffith theory which has been developed and modified by Orowan and Irwin for the case of small ductile strains at the crack tip. A generalized Griffith-Orowan-Irwin's concept was formulated in the terms of energy balance, that leads to equality between stress intensity factor and fracture toughness. On the other hand, in quasi-brittle materials the main crack may propagate by a thermally activated mechanism [1]. This process can be analyzed in the frame of the chemical kinetics approach and described by the rate theory [2]. The last leads to the Arrhenius type dependence for the crack velocity [3]: . kT vL where T is temperature, k and h are the Boltzmann's and Plank's constants correspondingly, L is an activation length and E+ is an activation energy [4]: E+= A. Sharon and D. Itzhak Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel The environmental behaviour of Duplex stainless steel containing additions of elemental tin or nickel powders has been investigated. Open circuit potential measurements a well as potentiodynamic tests were carried out for each sample immersed in 1N H2SO4 at room temperature. It is concluded that elemental additions of tin powder to the Duplex stainless steel improves considerably the corrosion resistance of the specimen rendering an environmental behaviour very similar to the wrought or cast Duplex steel. Addition of nickel powder to the same Duplex powder does not show any significant contribution to the corrosion resistance of the sintered specimen. A substantial change in the pore morphology of specimen containing tin powder has been observed when increasing the additive content. A smaller change in the pore morphology of powders containing nickel additive has been observed. Metallographical and S.E.M (Scanning Electron Microscope) observations have been carried out and correlated to the environmental behaviour. 3.1.4 X-RAY DIFFRACTOMETRY IN MATERIALS SCIENCE Lev Zevin Ben Gurion University of the Negev, Beer Sheva Chemical compounds used as materials usually have an uncomplicated crystal structure with a relatively small unit cell. It is the chemica! bond rather that any other factor that determines the structure of the crystal and the class of material. The physical properties of the material within a given class of compound, although related to the average structure, are greatly influenced by deflections from the average structure or by crystal defects. The mainframe of the crystal structure can be easily established from relatively nonprecise diffraction data. Not so, for crystal defects, which produces only secondary effects in the diffraction pattern, i.e., small variations in the position and shape of the diffraction peaks. Thus, peak profiles themselves rather than their integrated intensities are often greater interest to the materials scientist. Nowadays we are witnessing a spectacular revival of interest in powder diffraction. The reasons for this renaissance are many and varied, but the most significant single development is the fitting of certain mathematical and physical models to the total diffraction pattern. The elaboration of this technique has been facilitated by the development of automatic diffractometers and the dramatic increase in the amount and quality of the data that can be recorded in a given time. Achievements in modern instrumentation and data processing are characterized by precision in peak location of 0.00 T and peak width of 0.05° for a well-crystallized material. The following applications of modern X-ray diffractometry will be discussed: Development of residual strains and lattice anisotropy in IVB metal nitrides Residual strains and stresses in multiphase ceramics X-ray diffraction by modulated structures and diffusion study Refinement of crystal structures by powder diffraction data Diffraction effects in metals produced by light atoms-hydrogen an helium Anisotropic microstructural effects in materials Full-pattern approach in phase quantification J.2.1 STUDY IN IMPROVEMENT OF WEAR BEHAVIOUR IN HIGH KINEMATIC f PAIRS BY WAY OF A COMPUTER PROGRAM E. Berman* and S.I. Griinfeld** j *Depaitment of CAD/CAM/CAEJ **Department of Mechanical Engineering, Ben Gurion University, Beer Sheva, Israel The paper covers an improvement program related to wear behaviour in high kinematic pairs. The program has been worked out based on adequate mathematic model, where geometrical and mechanical factors of the kinematic pairs are taken into consideration. The program allows for a tridimensional and bidimensional graphic representation of the wear function, while making an estimation of possible critical zone. Although the calculation is iterative, the number of iterations is relatively small, the method used being the rapidly convergent method. The paper gives numerical examples, which have also been experimentally checked. 3.2.2 i i ASPECTS OF BEHAVIOR CONCRETE MACHINE TOOL STRUCTURES USING FINITE ELEMENT METHOD Constantin Ispas, Constantin Dogariu, Aurelian Craciunescu Polytechnic Institute of Bucharest, Romania The recent machine tools must satisfy, to be competitive, specified accuracy of shape and dimensions of the workpiece produced and it must show high technical performance with economical efficiency. To answer at this need, the research workers by machine tools field, searches to discover the new solutions, the new materials with remarkable properties. For machine tool structure elements, reinforced concrete simple and with resines was adopted, to take the advantage of the experience and knowledge accumulated in civil engineering and of inexpensive cost. Also, concrete has been used for machine tool structures as a material which improves the damping of vibration characteristic. The paper presents some aspects of behavior machine tool structures by reinforced concrete in metallic shape. The finite element method is used to determine the deformation state, the stress-slip values of a contact element describes of the interface between concrete and reinforcement, the local stress state. Material characteristic was determinated on the test bodies and on the material models. Also, the drying process and this secondary phenomena, the concentration and slow relaxation, was emphasized too. The results obtained by finite element method was used to establish the best design for machine tool structure elements. 3.2.3 *; A MODEL DESCRIBING THE CURVED ARRHENIUS PLOTS IN SELF-DIFFUSION OF METALS V. Segel*, J. Pelleg*, D. Fuks* and S. Dorfman** *Department of Materials Engineering, Ben Gurion University of the Negev, Beer Sheva, Israel **Department of Physics, Technion, Israel Institute of Technology, Haifa, Israel The temperature dependence of the diffusion coefficient is discussed along the lines of a model recently suggested, in which the total energy, Etot, per atom is concentration dependent. The application of the model was tested by actual experimental data for a few BCC and FCC metals. The basic assumption of the model are a) that the system of metal and vacancies can be considered as random solid solution of holes in the bulk and b) the formation energy of vacancies is concentration dependent. No other assumptions were made in the model and no preconceived mechanisms for diffusion are postulated. The usual Arrhenius equation D=Doexp[-l/kT*(E>Em)] (1) has been modified to take into consideration the mentioned assumptions of the model and it can be expressed as: D = Do exp[- E° + E m + A/( 1 + exp (E°/kT ))) /kT] (2) In the above equation D and Do are the diffusion coefficient and the preexponential factor, E v and Em are the migration and formation energies by a vacancy, and A, is a parameter which is connected with the interactions of vacancies. The term modifying the usual ' Arrhenius relation is given according to the equation (A/(I + exp (E°/kT))). This term takes into account the natural changes occurring in the vacancy concentration with temperature. The model was tested for FCC(Ni) and BCC(Nb, pTi, V). The choice of the metals was aimed to test the universal application of eq. (2), since it is known that some of the metals, "the so called anomalous BCC metals", show a strong temperature dependence beyond the slight curvature found in some !•('(' metals also. THE INFLUENCE OF SURFACE TREATMENTS OF ALUMINUM ALLOYS ON THEIR RESISTANCE TO CORROSION FATIGUE M. Landkof, J. Rezek, A. Cohen The influence of surface treatments on the corrosion fatigue resistance of aluminum alloys 6061 and 50X3 has been investigated. The surface treatments included sulfuric acid anodization and chromate conversion coating. S-N curves of the two alloys, bare and surface treated, have been constructed both in air and in 3.5% NaCl soln. Chromate conversion coating improved the resistance of both alloys to corrosion fatigue. Sulfuric acid anodization improved the resistance of AA5O83, but had a mixed effect on AA606I, where in some cases it increased the susceptibility to corrosion fatigue. This effect was attributed to the known susceptibility of the anodization layer to fatigue cracking. AA5083 was found to be less resistant to corrosion fatigue than AA6061, inspite of its well known corrosion resistance and its better fatigue resistance in air. The susceptibility of this alloy was probably caused by hydrogen embrittlement. 3 . 'i . I FORMICARYCORROSIONOFCOPPER :; I. Weisshaus, A. Kaufman and E. Erdan ORLIL Ltd. Night Vision Tubes & Equipment, Industrial Zone, P.O.Box 110, Kazrin 12900, Israel Pitting corrosion of copper and copper alloys was investigated intensively since the year 1950. There is an agreement about two types of pitting corrosion of copper as described in the book of Szkalarska-SmiaJowska "Pitting Corrosion". : Both types of corrosion refer to copper tubes used for water supply and in both cases the corrosion mechanism is related to the water composition. The pitting causing water A should be hard and contain high sulphate content and fairly low chloride content. Also, a '' deposited carbon film is important for the creation of the pitting. According to Cornwell copper without carbon deposit cannot reach the pitting potential. Mattson assumed that in carbonate water with sulphate ions a basic copper sulphate forms that enables the following reaction to occur: s 2Cu + H2O = Cu2O + 2H++ 2e- All the above mentioned works and many other refer to the pitting of copper in water. Only recently attention was paid to the type of pitting attack on copper where the species causing the pitting are not the sulphate and the carbonate in the water. * Copper tubes of heat exchanger units, suffer from a type of localized corrosion that causes leaks in the tubes within a short period of up to three weeks. A scanning electron microscopic examination of the corroded copper tubes surface and of the cross section shows that the corrosion appears as pits that develop to a network of microscopic grooves and caverens. The corrosion develops prefert ._,- along the grain boundaries. Analysis of the surface and the corrosion products by Auger electron spectroscopy detects y' mainly three elements, namely, copper oxygen and carbon. In addition there are traces of \ sulphur and chlorine. £ The corrosive media was suspected to be L :riixture of organic acid (acetic acid) with | humide air and water. The Handbook of Corrosion Data states that the copper and its f alloys, except those with high zinc, show good resistance to all concentration of acetic fc acid in the absence of oxygen or other oxidants. Contamination of the acid with air j increases the attack significantly. I The attack on the copper was repeated in the laboratory. |''i Specimens were immersed in a diluted and aerated solution of acetic acid. T[ I.I.;. I I STRESS CORROSION CRACKING OF STAINLESS STEEL IN BROMIDE HEAVY I BRINES I I P. Peled* and D. Itzhak** | *Bromine Compounds LTD. Israel I **Materials Engineering Department, Ben Gurion University of the Negev, Israel The stress corrosion cracking (SCC) of stainless steel in bromide heavy brine solutions, was investigated. Susceptibility to SCC was exhibited in exposure to boiling ZnBr2, as well as LiBr, at a temperature of 1450°C. Previous reports showed no SCC susceptibility in exposure to NaBr, Zn/CaBr2 or CaBr2 heavy brines and some inhibiting effects of the bromide addition in other environments. 3.3.3 THE EFFECT OF MELT TEMPERATURE ON THE ELECTRICAL RESISTIVITY AND CRYSTALLIZATION TEMPERATURE OF AI91 - La5 - N14 AND AI91 - Ce5 - Ni 4 AMORPHOUS ALLOYS V. Manov*, D. Shechtman*, A. Rubshtein** and A. Voronel** •Department of Materials Engineering, Technion, Haifa, Israel **Department of Physics, Tel Aviv University, Tel Aviv, Israel New low density amorphous alloy ribbons with high Al concentration have been produced by melt spinning in vacuum. The metallic alloys were melted in alumina crucibles prior to their ra;id quenching onto a copper drum surface. Contact of the molten alloys with the crucible and with residual gases in the vacuum was prevented by a layer of molten salts. Ductile rapidly solidified ribbons, the thickness of which is about 20 micrometers have been prepared following different soaking times of the melt. Two series of experiments were conducted. In the first, the molten alloy was soaked for 5 minutes at 1273, 1373 and 1473K. In the second, the alloys were soaked for 10 minutes at 1473K followed by 5 minutes at 1273 and 1373K. The amorphous structure of all the ribbons has been confirmed by an X-ray diffraction study. The specific electrical resistivity and its dependence on the preparation conditions and on the alloy's temperature was studied over a large temperature range at heating rate of 0.05 K/s. The electrical resistivity thus changes from 40 to 49 Ohmcm for AI91- Las - Ni4 amorphous alloy ribbons and from 38 to 44 Ohmcm for different samples of AI91 - Ces - Ni4 alloys. The variation of crystallization temperature and activation energy of crystallization for the ribbons were determined. 3.3.4 j USE OF ELECTRICAL EQUIVALENT CKCUITE TO SIMULATE SOME CASES OF j PROTECTIVE COATINGS UNDER CORROSION CONDITIONS £ Joseph Hazan and Joseph Yahalom i; i Department of Materials Engineering, Technion, Israel Institute of Technology, Israel I f In this work, the behaviour of (he interface under corroding conditions is simulated by electrical equivalent circuits. The effect of the protection by anodizing, painting and chromating is also described and discussed. In each case, attention is given in the simulation, to the electrical parameters of the intact coating layer, to the porosity of the protective film and to its evolution during the corrosion process. Simulated results using various sets of parameter values according to experimental data are reported and the most directly interesting quantities from the point of view of corrosion, protection and diffusion are detected. Not all the electrical components related to the different layers can be determined from the narrow experimental range of frequency. The break points at very low and at very high frequencies in the log z vs. log f Bode diagrams are not always detected in the case of anodized aluminium alloy (2024) and the small capacitive loop at very high frequencies. In the case of a chromic- phosphoric conversion later on zinc is not found in its entire form. The influence of the separation of the time constants in the determination of the different impedance parameters is emphasized. Finally, the distortion of the impedance diagrams due to diffusion effects and to the inhomogeneity of the surface are discussed. 3 . •> . I SURFACE DIFFUSION AND COATING OF SiC AND B4C BY INTERACTION ; WITH METAL POWDERS i P. Mogilevsky*, 1. Gotman*, E.Y. Gutmanas* and W.A. Kaysser** •' *Department of Material Engineering, Technion, Haifa, Israel **Max-Planck-Institut, Stuttpart, Germany SiC and B4C are known to react with metals at high processing or service temperatures. This interaction has a detrimental effect on the properties of metal matrix composite materials reinforced by SiC and B4C fibers or whiskers. Controlled reactions, and especially those accomplished before the final processing, may be helpful in protecting the ceramic/metal interface from further degradation. In the present work, the interaction of SiC and B4C ceramics with Cr and Ti powders was investigated. Experiments were performed on SiC or B4C plates immersed into the metal powders. Partially immersed samples were used for investigation of the surface diffusion of the metal atoms on a ceramic surface. It has been shown that SiC and B4C can be successfully coated by interaction with Cr and Ti powders. During vacuum heat treatments at 1173- 1473°K,reactive diffusion of metals atoms along the ceramic resulted in the formation of coatings OP the ceramic surface. The microstructure and phase composition of the coatings obtained were studied employing X-ray diffraction, SEM/EDS and Auger spectroscopy. The coatings have a multi-layer structure, the phase composition of the interfacial layer depending on the thermodynamics of the corresponding ceramic/metal system. The coatings formed on the SiC surface were found to contain carbides and silicides of the corresponding metal, the outer layer being a carbide or a mixture of a carbide and a silicide. Treating B4C in Cr powder yielded a coating which consisted of Cr borides and amorphous carbon, the outer layer containing only the borides. This coating growth was shown to be controlled by diffusion. Thermal stability of the coated and uncoated ceramic/metal interfaces was estimated by placing SiC and B4C plates into Fe- and Ni-base matrices and annealing the obtained model composites at 1273-1473°K for 1-10 h. The coatings obtained by treating SiC in Cr and Ti powders have been found to considerably improve the thermal stability of SiC in Fe and Ni matrices. A preliminary study of the thermal stability of B4C in a Fe matrix has shown that the coating of this ceramic by interaction with metal powders may be effective in preventing chemical interaction at Bimetal matrix interfaces. i.A.l ELECTROPHORETIC DEPOSFTION OF HYDROXYAPATICE COATINGS FOR MEDICAL APPLICATIONS A. Zhitomirsky, L. Gal-Or Institute of Metals, Technion, Haifa, Israel In the last few years many studies have been proven that hydroxyapatite (HAp) has excellent biocompatibility as its chemical composition is identical to that of bone tissue. Clinical observations have shown that when HAp is implanted in bone, a tight bond between the bone and the implant develops. Unfortunately, HAp has a low tensile strength and its resistance to fatigue failure is also vc.y low. In order to overcome these drawbacks co; HAp coated Ti implants are currently of much interest. Coatings are found to provide good biocompatibility, ability of bonding to bone, enhacement of new bone formation and corrosion protection of the metallic substrate. HAp ceramic fibers are of a high potential for development of composites. Considerable attention has been given to develop low- cost method for manufacturing continuous, uniform, fine grained fibers. Problems of stoiciometry, sinterability, formation rate and thickness control are also of great practical significance, It is the aim of this study to develop HAp coatings on titanium alloy implants and HAp fibers by electrophoresis. The HAp precipitaion experiments were performed at variable experimental conditions. Powders of varying degrees of crystallinity and thermal stability were synthesized, studied and used for electrophoretic deposition. In order to prevent compositional changes of the coating during the sintering stage, anodic oxidation of the substrate was performed for development of protective layers on the TiAlV alloy specimens. The obtained oxide films are found to contain phosphorus in addition to the alloying elements as well as oxygen. Carbon fibers of 7 |im diameter were used a a template for HAp fibers development. In contrast to results of some previous works submicron HAp powders were successfully deposited on the Ti alloy specimens and carbon fibers. The developed technology of fine HAp powder preparatoin allows to obtain relatively high deposition rates at low current densities. Variation of deposit weight with time and applied voltage were studied and i/nalyzed. Sintering behaviour of HAp coatings was studied at temperatures below the transition point of a + p -> P in the Ti Al V substrate. It has been established that low temperature densification is a result of the use of submicron particles. In our work the problem of coating densification has been also approached by use of cementitious bonding. A technology has been developed for preparation of hollow HAp ceramic fibers. This technology allows the simple solution of some technological problems in this field. 3.4.2 MICROSTRUCTURE, PHASE COMPOSITION AND RESIDUAL STRESSES IN PLASMA SPRAYED THERMAL BARRIER COATINGS M. Levit, S. Berger and B.Z. Weiss Department of Materials Engineering, Technion City, Haifa 32000, Israel The development of the thermal barrier coatings (TBCs) has received a great deal of attention in recent years. The present investigation was conducted on a duplex system consisting of a ZxQz-1 V2O3 outer ceramic layer over a NiCrAl Y inner metallic bond coat layer. The state of residual stresses, bonding mechanisms, microstructure, phase composition, interface phenomena, ir teri jnellar contact and internal lamellae structure of thermal barrier coatings were studied. The coatings were deposited by atmospheric plasma spraying on a Ni-based alloy substrates, which were kept at different temperatures during deposition. The research was carried out by using Transmission and Scanning Electron Microscopies combined with Energy Dispersive X-ray Spectroscopy, Optical Microscopy and X-ray Diffraction. It was found that both the plasma-sprayed bond and the ceramic coatings have a characteristic lamellar microstructure. The bond lamellar is composed of an outer amorphous film of oxides, an intermediate thin layer of columnar oxides grains and an inner polycrystalline region consisting of elongated intermetallic grains. The ceramic lamella is composed of an outer amorphous film and an inner region of columnar and equiaxed grains of the metastable tetragonal t-ZrO2 phase. Increasing the substrate temperature from 75°C to 500°C has not a significant influence on the microstructure, but the state of residual stresses in outer ceramic layer changes from tension to compression. The effect of the substrate temperature on the microstructure, composition and morphology of the interfaces, and on the residual stresses in the ceramic layer will be discussed. A mathematical model predicting the temperature and the velocity of the ceramic and metallic powder particles during the plasma spraying and before impact to the substrate was developed. The analytically calculated data have shown a good agreement with experimental results. 1.4.1 I PRODUCTION OF Cr BASED COMPOSITE COATINGS IN THE PRESENCE OF § ADDITIVES j 0. Berkh, S. Eskin, J. Zahavi i The effect of additives on particle codeposition with a chromium matrix is considered. It is shown that surface active additives act as particle codeposition stimulators or influence the morphology and phase composition of the matrix. Codeposition stimulators can either reduce electrolyte surface tension or be adsorbed on the surface of the cathode and particles changing the particle surface charge and adsorptivity. Additives involving matrix phase transformation can improve hardness and wear resistance of the composite coating and thus intensify the positive effect of the incorporated particles. Saccharin effect on AI2O3 particle codeposition with Cr-and Cr-Ni alloy from electrolyte on N, N-dimethylformamide base has been investigated. Saccharin introduction into electrolyte does not increase amount of AI2O3 particles in composite Cr-Ni coating but reduces coating deposition rate, internal stresses and wear of deposits. In order to reveal the role of saccharin in AI2O3 particle codeposition with Cr-Ni alloy, cathodic polarization measurements during codeposition process also spectral tests of electrolytes and partical electrophoretic mobility examination were carried out. On the base of obtained data mechanism of saccharin action is discussed and recommendations for CrMi-Al2O3 composite production are proposed. 3.4.4 DIAMOND COATINGS Z. Klein, A. Markovitch, A. Shalmon ? Dept. 27, Rafael, POB 2250, Haifa 31021, Israel I Hot filament and microwave plasma assisted CVD processes have been used to produce diamond coatings. Thin diamond films of 1-40 |im have been deposited on silicon substrates up to 25 mm diameter, at deposition rates to three microns per hour. A free standing diamond film, 40 \im thick was obtained by etching the silicon substrate. Influence of several process parameters on the deposition rate and on the quality of the diamond films was investigated. * filament materials and shapes * filament and substrate temperature * distance filament - substrate * MW power * substrate preparation * Composition concentration and flow rates of gases Characterization of the diamond films was done by Scanning Electron Microscopy, Raman and Infrared Spectroscopy. 3.4.5 f MECHANOCHEMICAL METHODS IN MATERIAL SCIENCE t i PJu. Butyagin Institute of Chemical Physics Russian Academy of Science Kosygina Str. 4, V-334 Moscow, 117977 Russia The oldest mcchanochemical process is the production of the fire during friction of wood sticks. By the friction the cellulose macromolecules are ruptured and free radicals are formed. Free radicals initiated chain oxidation of cellulose. The reaction of oxidation accompanied by heating. The heating leads to combustion. The next old mcchanochemical technology is the plastication of rubber. More recent technology is the preparation of superhard materials by the mechanical treatment of initial elements mixture. The example of mechanochemical processes in material science are surface modification, activation of sintering, low temperature synthesis and alloying, soft methods of material testing and many others. In the base of all above listed efforts lies the following fundamental phenomenon. In the course of mechanical action on solids the elastic energy not immediately transformed into Joule heat. Between action and heating there exists therefore a sequence of the nonequilibrium intermediate states: MECHANICAL WORK - - - -• ELASTIC ENERGY STRUCTURE H.ECTRONICALLY VIBRAT1ONAL TRANSLATION DEFECTS EXCITED STATES EXCITED STATES MOBILITY JOULE HEAT AND STABLE DEFECTS * Every intermediate state can be characterized by the energy yield, life time and chemical reactivity. For a lot of systems the nature of these states are determined. The mechanical activation consist in the production of structure defects. Mechanical defects accelerate the sintering and other diffusion controlled processes,dissolving, chemical and physico-chemical transformations, in (he limiting case the mechanical activation leads to amorphous state. It is a way to the production of materials with news property. The modification of surfaces is the result of mechanical treatments of powders in chemical active media (gases, liquid). The fracture and friction of particles by treatment lead to surface disordering. On the surface arise low coordinate atoms, free radicals, deformed interatomic bonds, electron exited states. All these chemical active structures decay as a rule in the course of physical relaxation and reaction with oxygen or other gases. But it is also possible to involve "11 the short living active centers and exited states in useful chemical transformation. In such a way one can prepare highly disperse powder for composite materials. The last group of processes based on the effect of translation mobility by plastic deformation. The deformation mobility on atomic level were simulated by the molecular dynamic method. The attention to this effect is connected with the synthesis of the materials in solid phase without dissolving, heating or melting the mixture of reagents. If the products of inechaaoehemical synthesis were formed in cold regime they have disordered nanocrystalline or amorphous structure. 1.1.1 I RESIDUAL MECHANICAL PROPERTIES OF ABLATIVE COMPOSITES ON t| EXPOSURE TO HIGH TEMPERATURES \ Haya Weisshaus, Israel Engelberg * ADA, P.O.Box 2250, Haifa 31021 Ablative composite materials exposed to high temperatures are subjected to two types of changes. The first is a chemical change of the polymeric matrix while pyrolysed. The second is composed of all the physical changes in matrix dimensions and the reinforcement's relative location within it. Erosion is an additional change caused when the source of heating is exhaust gases of rocket motor engines. These changes result in degradation of the initial mechanical properties of the composite. Ablative components are designed considering this degradation and calculations even maximize it by diminishing values to zero as a safety factor. However, the price in extra- load is especially expensive in avionic components. This study was aimed to measure the residual mechanical properties of the ablative composites at the actual high temperatures of application, as related to these temp, and to factors of their composition and fabrication. Connecting the information with the erosion behavior will enable implementation of results in practical calculations, improving the component's design. The relationship between temp, and pyrolysis mechanisms is quite known for Phenolic resin, the most abundant matrix. It is also believed that the heating rate and exposure duration as well as its combination with thermal conductivity at the specified temp., has a significant influence on the residual mechanical properties. Shape and dimensions of the specimen become therefore relevant parameters. In addition to these it is expected that the composition of the raw material, its manufacturing and polymerization processes will affect the residual mechanical properties. This study began with a carbon/phenolic ablative composite. It is a rayon precursor carbon fiber, satin weaved reinforced composite. Two procedures were chosen to fabricate plates of specified thickness, from which samples were cut out. Sizes were in 4.1.2 ji STRESS AND FAILURE ANALYSIS OF TAPERED ADHESIVE JOINTS if § A. Buchman, F. Weinstein, Y. Holdengraber, I. Honigman and H. Dodiuk % RAFAEL, P.O.Box 2250, Haifa 31021, Israel >, I Advanced thermoplastic composites have been recently introduced to the aerospace and I military market. As consequence the joining ol thermoplastic composites have become a critical manufacturing step. Due to geometrical imperfections and production processes of a layered composite with bonded joints a tapered adhesive is sometimes formed instead of a parallel one which leads to a loss of structural stress. A correlation between numerical results obtained by the Finite Element (F.E.) method and experimental data for parallel compared to tapered butt joints under tensile load was studied. The experimental results were obtained with two kinds of adherents (metallic and plastic) and two adhesives (flexible and brittle) for various adhesive layer thicknesses and taper angles. Two linear finite element simulations were constructed for both joints. The numerical results were used for modelling the ultimate tensile strength values and the failure modes for the various thicknesses of the adhesive joints tested. The numerical and test data results have shown that a thinner parallel adhesive layer leads to a stronger joint. An optimum adhesive layer thickness was found for the tapered configuration (0.4-0.5 mm). This thickness was achieved when the stress value and its gradient were distributed in an optimal ratio. Then, the mode of failure was changed from adhesive (interfacial) to cohesive (in the adhesive). The enhanced sensitivity found for the tapered joint strength as a function of its thickness leads to the conclusion that in composite layered bonded structures such joint should be prevented. Thus parallel joints in addition to other important parameters (surface treatment and material properties) should be considered. 4.1.3 FATIGUE MECHANISMS OF 95 / 5 Pb / Sn MICRO SOLDER JOINTS UNDER FULLY REVERSED SHEAR Nahum Nir*. Arthur R. Storm*1", T.D. Dudderar** *AT&T Bell Laboratories, Murray Hill, NJ., U.S.A. **Rafael, POB 2250, Haifa 31021, Israel In this study SEM Failure Mode Analysis (FMA) has been used to develop a new understanding of the mechanisms of Low-Cycle Fatigue (LCF) in 95/5 Pb/Sn solder micro-joints typical of those being used in high density micro-electronics. As a result it is now understood that many of the same phenomena that come into play in the LCF of high performance structural alloys play the same roles in solder micro-joints. However, it is necessary to also consider the added dimension of a relatively large (compared to the micro-joint volume) grain size which under all conditions makes microstructure (1) an important factor in determining the effective mix of active fatigue damage mechanisms and, under certain (relatively common) conditions of micro-joint geometry, (2) a major factor in determining the resulting fracture surface morphology. These understandings support the development of rational methodology for the optimization of flip-chip assembly processes, the selection of appropriate pad metallizations and the refinement of solder alloys for improved micro-joint reliability. 4.1.4 FRACTURE TOUGHNESS MEASUREMENTS FOR CERAMIC MATERIALS A. Ashur, A. Cohen Rafael, M.O.D. Hifa, Israel Fracture toughness testing has recently gained importance in ceramic materials characterisation. There are several methods of testing fracture toughness in ceramic materials but there is no standard method for KJC measurement. The fracture toughness values in ceramic materials depend on production process, microstructure, specimen geometry and the specimens preparation technique. In this work we have tested two different materials: ZnS and Slip Cast Fused Silica (SCFS), and compared the relative merits of the following testing methods: Single edge notch beam (SENB) Chevron notch. Indentation crack length and Indentation strength. The ZnS had been produced by CVD process. The material had no faults such as microcraks, porosity, etc. The Kic values, as measured by Chevron notch and by SENB methods were very similar, but different values were obtained by Indentation Strength method and by Indentation crack length methods. For SCFS material there was a considerable difference between the SENB and Chevron Notch KJC results. The scatter was similar for both methods. Indentation crack length and Indentation strength methods were inaplicable in this case, since the material is porosive. In the Chevron notch method, the crack geometry changes during its propagation. Consequently the influence of the specimen geometry on measured Kic values is reduced. J 4. ! .5 THE EFFECT OF IMPURITIES ON THE TENSILE ELONGATION OF BERYLLIUM O. Yeheskel Nuclear Research Center-Negev, P.O. Box 9001, Beer Sheva, Israel From literature survey the effects of beryllium oxide content and the content of impurities like iron, aluminum, silicon and magnesium , on the room temperature tensile elongation of beryllium were studied. The data from the literature is related only to beryllium which was processed by the powder route. No indication exists to a single metallic impurity which affects tensile elongation. The known relation ' that the tensile elongation is reduced with the increase of beryllium oxide content is found, but linear regression shows large spread. The effect of ratios of different impurity contexts on tensile elongation are examined as well. It is found that when Be() content is multiplied by the molar to atomic ratio of BeO/Si linear relationship with elongation exists. From linear regression the relationship between the tensile elongation, e, and the BeO content molar to atomic ratio is: e(%) = 4.02 - 5.3'10'3 • (wt%)BeO* (mol%) BeO/ (At ppm) Si. The ./egression coefficient r = 0.79, Similar relationship with shallower constant and larger spread is found in these specimens tor the Al content multiplied by the molar to atomic ratio BeO/Al. The atomic ratio Fe/Al, which is correlated to the phase FeAlBe, shows no relationship to the tensile elongation, indicating that this phase, has no crjeial effect on tensile elongation at room temperature as opposed to elongation at high temperatures ' . It is found that for specimens which underwent HIP consolidation , maximum elongation of about 4.5% is reached al the grain size range of (>-9u,m. It is shown in the present work that grain growth in beryllium thai is processed in the powder route ' , can be correlated with the molar to atomic ratio BeO/Si. It is postulated that the presence of silicious phases at the grain boundaries enables the annihilation of dislocations which are generated at Che BeO/Be interface due to the thermoplastic stresses during the cooling from processing temperature. The reduction of dislocation density contribute to the increase of tensile elongation. The possibility of slight grain boundary sliding in beryllium al room temperature is discussed. Ways of increasing the tensile elongation of beryllium al room temperature are given. .Z. ] \ THE PREPARATION OF FIBER REINFORCED ALUMINIUM SiCr/ 6061 BY | DIFFUSION BONDING f M. Paz, J, Mironi, N, Atzmon, M. Elkaiyam I Two processes for the preparation of Silicon Carbide fibers - reinforced aluminium - Hot j1 Pressing (HP) and Hot Isostatic Pressing (HIP) - were examined. Various basic L- configurations - plane, cylindrical and "channel like" - were produced and characterized. The effect of the parameters on the mechanical properties of the configurations were studied. The basic configurations produced and characterized were variously combined in order to ascertain the possibility of their further employment. .2 COMPARATIVE STUDIES CONCERNING THE BEHAVIOR OF RESIN / FIBRE GLASS COMPOSITE MATERIAL Ispas Constantin*, Gramada Dan** •Polytechnic Institute of Bucharest, Romania **S.C. SIMTEX S.A., Romania One of the major directions in technological enhancement consists in investigations to obtain durable, light-weighted, various, resistant, easy machinable materials, and which should simultaneously cover more specific requirements. Composite materials (CM), which accomplish the majority of these conditions, have known in the last years an explosive multiplication of their fields of application. One of them-machine constructions, and more particularly machine-tools accomplishment - have been an interesting area for extending the use of composite materials. In this spirit, in Romania there have been developed studies and searches for improving the behavior of the machine-tools in the cutting process and to elaborate new types of composite structures. A step in this searches consisted in comparative studies on the behavior of various samples of CM in different conditions. There have been selected for experiments samples of CM with matrix of unsaturated polyester resin with medium viscosity and fast polymerization, reinforced with four kinds of fibre-glass type E. All the working materials are in the current production of specialized firms in Romania. The samples were produced by the direct manual forming process. On specific testing stands, there have been experimented the behavior of samples on static, dynamic and tribological (the response at wear and tear stress and defining the friction coefficient) applications. In the paper are comparatively presented the results obtained during the experiments accomplished on the presented CM and some other plastic and metallic (ferrous ans non-ferrous) materials, currently used in machine-tool building. The results permitted the elaboration of some recommendations regarding the optimum intimate structure of CM resin/glass in the specific applications in machine-tool building. A . ? . i RECRYSTALLIZATION OF TUNGSTEN BASE HEAVY METAL ALLOYS Chaim Weinberger and Dov Chaiat TAAS - Israel Industries Ltd. The traditional-tungsten base heavy-metal alloy is a composite material, containing a minimum of 8.5wt% of tungsten grains embedded within a W-Ni-Fe matrix. Liquid phase sintering of this two-phase alloy results in spherical tungsten grains, with an average grain size of 30± 10 micrometers. Rotary swaging is a well-known technology used as part of a thermomechanica) heat treatment in tungsten alloys. Tungsten-base alloy bars are usually swaged up to a maximum 30% reduction in area. The swaging results in a slight deformation of the tungsten grains. Several recrystallization heat treatments were performed at temperatures of 1430 and 1500°C in order to determine recrystallization behavior with various amounts of cold working of the two types of alloys: A-90 and A-95. 4.2.4 LASER SURFACE ALLOYING OF FERROUS ALLOYS WITH CrB2: SOLIDIFICATION BEHAVIOR AND MICRO • STRUCTURE G. Shafirstien*, S. Ariely**, M. Bamberger*, F. Maisenhalder** and M. Langohr** *Department of Materials Engineering, Technion, Haifa, Israel **DLR Stuttgart, Germany A CW-CO2 laser was used to alloy the surface of a-Fe and AISI 1045 steel plates with CrB2 by the powder injection method. The OB2 particles were partially dissolved in the bath forming a melted layer of Fe-Cr-B or Fe-Cr-B-C its thickness and B content depends on the laser parameters and the substrate's thermo-physical properties. The typical microstructures were: 1) Columnar iron-borides which grow on the residual chromium borides, 2) Iron dendrites which grow on the substrate, 3) Eutectic and 4) a layer of iron borides which engulfs the OB2 particles. The solidification behavior resulting the co-existence of these phases and its dependence on the laser operating parameters will be discussed based on a simplified mathematical model. 4.:'."' ULTRASONICS AS A RESEARCH TOOL IN POWDER TECHNOLOGY O. YeheskeJ, H. Klimker, Y. Gefen, M. Ganor Physics Division Nuclear Research Center - Negev P.O. Box 9001, 84190 Beer Sheva, Israel When an ultrasonic sound wave is travelling through powder particles pressed together, its velocity is affected by the nature of the phases comprising it, the quality of the bom! between the particles and the volume of pores. The longitudinal and transverse sound velocities thus realized, are related to the elastic moduli of that bulk. This is the theory underlying the foundation to the possibility of measuring the clastic properties of powder compacts as they are being densifled via a I'owder Metallurgy (P/M) route. Examples of sound wave velocity measurements on post sintered metals and ceramics specimens and during Hot Isostatic Pressing (HIP) of powder specimens are shown. Changes in sound velocity during densificalion are related to various stages of the sintering processes while they occur. A measure to the material quality can thus be set. The technique was successfully applied to study the effects of the HIP cycle parameters e.g., temperature, pressure and time, on the dcnsificalion mechanisms in l-e, NaCl and Ti Al. The agreement of relevant theories to experimental data will be reviewed. 4. EFFECT OF PROCESSING ON MICROSTRUCTURE AND PROPERTIES OF TUNGSTEN HEAVY ALLOYS E.Y. Gutman, D. Zack and D. Chalat Department of Materials Engineering, Technion, Haifa, Israel. The effect of high energy attrition milling, high pressure consolidation and of alloying on niicrostructure and mechanical properties of tungsten heavy alloys was investigated. High level of homogeneity was achieved by attrition milling of the powder blends. Alloying elements enhancing diffusion and high pressure consolidation lower the temperature or shorten the exposures at temperatures which provide full density. All this provides retention of fine scale microstructure resulting in higher yield stress and hardness of the alloys. 4.3.2 STRUCTURAL CHARACTERIZATION OF EPITAXIAL THIN FILMS BY RECIPROCAL SPACE MAPPING Gerardo H.O. Daalderop, Tom R. Ryan Philips Analytical X-Ray Almelo, The Netherlands By use of X-ray diffraction a wealth of information about the structural properties of materials can be obtained. In this contribution we will specifically focus on the use of reciprocal space mapping to characterize epitaxial thin films. The distribution of X-ray intensity around the reciprocal lattice points can give direct evidence of the presence of pseudo-morphio coherent, relaxed incoherent, tilled growth, sub-grain boundaries or sample curvature. To achieve this, it is essential that the integration volume in reciprocal space, determined by the resolution of the optics of the diffraclometer, is less than the width of the X-ray intensive in reciprocal space. In this contribution, the concepts will be introduced briefly, followed by examples dealing with 111-V coherent layers, II-VI incoherently grown layers, HTo superconductors and magnetic metallic multilayers. The advantages are shown of matching the optics to the materials problem. This work was done with the Philips Materials Research Diffractometer where the optics can be changed within seconds. We demonstrate how this interrhangeability is crucial for the analysis of a wide range of slructural problems. 4. i. MICROSTRUCTURE OF Al-U ALLOYS SOLIDIFIED AT COOLING RATES BETWEEN 0.03^.5 K/SEC A. Munitz, V.Y. Zenou, C. Cotler, A. Zahavi, and Z Barkai Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel High purity aluminum (99.99%) and high purity uranium (99.9%) were used to prepare Al-U alloys with U concentration ranging between 15-27 wt.%. Alloys with the desired composition were melted in a resistance furnace in an alumina-coated graphite crucible under argon atmosphere. The microstructure was examined utilizing scanning electron microscopy with EDS capabilities. The eutectic composition was found to be an increasing function of the cooling rates. The results are discussed in term of existing solidification theories. U: 4.4.4 IMPROVING PRODUCT DESIGN THROUGH A CONTROLLED EXPERIMENT Benny Milman*, Issachar Sirota*, David M. Steinberg** *TAAS Israel Industries, POB 1044, Ramat Hasharon 47100, Israel **Tel Aviv University, Ramat Aviv 69978, Israel One of the important goals of quality management in today's competitive marketplace is to build quality into products and processes at the development stage. The use of statistically controlled experiments, in which several parameters are studied simultaneously, can help accomplish this goal efficiently. This paper describes a case study that illustrates the utility of controlled experiments in product development. The customer required improvements in the safety of a pyrotechnic ignitor used in one of the products they purchased. The safety improvements could be met by replacing the "match- head" initiator by a type 1A/1W no fire initiator. However, there was concern that changing the initiator might degrade other important product performance characteristics. A controlled experiment was designed to compare three different initiators, the booster charge and the main charge. The experiment quickly and efficiently pointed to a superior initiator and the optical charges to maintain high performance with enhanced product safety. COMPUTERIZED SYSTEM FOR EVALUATION OF ENERGY ABSORPTION DURING LASER TREATMENT OF METALS Dr. M. Geller, Dr. E. Armon and Prof. M. Bamberger Department of Materials Engineering, Technion, Haifa, Israel Knowledge of the interaction of a workpiece and laser radiation is of extreme importance in application of laser technology to materials processing. At present, only relatively few publications contain relevant quantitative data. In the present work a new method was developed for determination of the energy absorbed by the substrate during laser irradiation. This was done by solving the "Inverse Problem of Heat Conductance" for the treated metal with a view to determining the temperature-time pattern in the substrate, which in turn yielded the heat flow into the workpiece and the temperature of the treated surface. By this means the coupling between laser radiation and matter was quantitatively described, as function of the surface temperature. The resulting equation was used in a simulation algorithm for the laser surface heating, which finally yielded the thickness of the treated layer as function of the laser operating parameters. The calculated and measured values are in quite good agreement. I I /• 4.4.1 THE INTERFACE FORMED BETWEEN PbBiSrCaCuO HKiH-Tc SUPERCONDUCTOR CERAMIC AND Ag OR Ag-BASED ALLOYS N. Froumin, J. Baram and M. Polak Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel Properties of interface formed between high Tc superconducting materials and metals are of a great importance due to their effects on the performance of practical devices. We have studied the interactions between PbBiSrCaCuO and silver: 1) deposited as a thin film subjected to 3()0-7()0°C heat treatments, and 2) as the metallic melts in wetting sessile drop experiments. The interface chemistry of the deposited film was examined by X-ray Photoelectron Spectroscopy (XPS), combined with argon sputtering. Elemental diffusion into the silver overlayer with significant temperature-dependent segregation of bismuth at the silver surface. The contact angle obtained in the wettability experiments for silver melt on PbBiSrCaCuO was 78 degrees with improved wetting effects in the following alloys: Ag-4%Bi, Ag-4%Pb and Ag-4%Cu. Both EDAX analysis of the drop/ceramic interface and AES analysis of the drop surface and periphery indicate dissolution of the ceramic elements in silver, segregation of the bismuth on the top surface of the drop and fonnation of an interaction zone at the drop periphery, containing silver, less copper, more bismuth and calcium than in the ceramic. Furthermore, there is evidence for the presence of some silver on the free ceramic surface. Correlation is made between these XPS results with reported results on contact resistivity in the system BiSrCaCuO/Ag films. The wettability results of PbBiSrCaCuO ceramic by liquid silver or silver alloys can be used for optimization of adhesion in the composite materials, and therefore eventually enhance electrical properties. 4 . -'I..'' DEPOSITION OF DIAMOND-LIKE CARBON FILMS BY LASER PLASMA TECHNIQUE J. Karpman, M. Riabkina-Fishman, J. Zahavi Israel Institute of Metals, Technion. Diamond-like carbon films (DLC) were prepared by 193 nm, 25 ns pulse duration, 2-10 Hz frequency, ArF excimer laser ablation of a high purity graphite target. Laser-plasma enhancement by means of special electrode, near the target and substrate and bias was also used. The effects of substrate temperature, laser flux and in situ laser pretreatment of the substrate surface on the optical, mechanical properties and electrical resistivity of the films were investigated. Film thicknesses were 40-1200 nm, substrate temperature ranged from room level up to 250°C; laser fluxes -107 -5 • l()ll) W/cm2. SEM, Ellipsomsometry, X-ray analysis, Auger and Raman spectroscopy, IR transmittance, were used for coating characterization. Adhesion of films to substrates was measured by scratch testing and by a method based on measurement of the tear effort. We deposited amorphous, smooth, hard films with good adhesion. It was found out that as laser flux density increases, the amount of particles, knocked out of the target, also considerably increases. Electrical discharge generated by the laser plume also enhances this trend. Laser-induced plasma appreciably (as much as 3-5 tiines) increases the deposit growth rate owing to additional etching of the target. Adhesion and hardness of films increase steeply as substrate temperature and laser flux density rise. Laser-induced plasma has little effect on adhesion properties but increases film hardness. Pretreatment of the substrate by diamond paste does not affect growth rale, film morphology and does not substantially improve adhesion strength at the low substrate temperature. IR measurements show considerably transmittance throughout the whole range of 400-4000 cnr'. 4.4. i RECONSTRUCTION OF SURFACE AND ENVIRONMENTAL SENSITIVE MECHANICAL BEHAVIOR OF METALS E.E.Glickman Graduate School of Appl. Sci. and Technol., the Hebrew University, 91904, Jerusalem Sufficient reduction in specific surface energy resulted from adsorption, wetting and electrical charging is often assumed to play a decisive role in environment induced degradation of mechanical properties of solids (Rehbinder-Westwood effects of plasticity). But neither surface energy-mechanical properties relations nor a mechanisms which may be responsible for such a relation are well established. The present paper offers a brief review of Surface Energy Effects in Metal Plasticity (SEEMP). A special emphasis was made on the recent direct observations of kinetics of subcritical crack growth and voiding, grain boundary sliding and creep in simple model systems under controllable decrease in specific surface energy. Relevant fractographic and acoustic emission finding are also discussed. Proceeding from these data we suggested a microscopic mechanism of SEEMP whose basic concepts may be formulated as follows: (i) SEEMP results from an acceleration of diffusion mass transfer in a near-surface region; (ii) an essential reduction in a specific surface energy y (for example from wetting of a solid metal by a liquid one) leads to an essential decrease in the formation energy Uk ^ y of kinks (semicrystalline positions) located at surface ledges and of vacant sites at smooth terraces; (iii) thus, transition from atomically smooth to atomically rough surface which consists in a drastic increase in thermal equilibrium concentration of these defects Q »= exp -yAT may well take place; (iv) this in its turn increases the efficiency of the surface as source and sink of point defect involved into diffusion controlled processes of creep, voiding and subcritical crack growth in the vicinity of the surface. Exponential relations "specific surface energy y-crack velocity (rale of voiding) creep rate" observed on experiments in near-surface region give a good evidence in support of the suggested mechanism of SEEMP. The results are of interest for understanding one of the basic mechanism of environmental sensitive mechanical behavior of metals. 4.4.4 THE NKW METHOD OF CRYSTAL PERFECTION CHARACTERIZATION USING X-RAY BRAGG REFLECTIONS Yuri Rosenberg School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel A knowledge of the degree of the crystal perfection is of fundamental interest for applied research where these crystals are used. X-ray diffraction on the strength of its nature is one of the most appropriate methods for crystal lattice imperfections study. One of the widely used approaches in this field is based on the comparison of experimentally measured integrated intensities Int (hkl) of X-ray Bragg reflections (hkl) with the results of calculations by some theoretical model of structure defectivness. As is generally known for any crystal the experimentally measured value Int (hkl) for every reflection does lie in the range with well-specified limits. The lower limit Dyn (hkl) corresponds to ideally perfect crystal, the upper one Kin (hkl) - to ideally mosaic crystal, the proportion Kin (hkl) / Dyn (hkl) depends on the structure factor of considered reflection and X-ray wavelength used and may be as high as 100. The theoretical description of X-ray diffraction in perfect and slightly distored crystals - dynamical theory is highly reliable as well as the kinematical theory, describing the X-ray scattering from ideally mosaic crystals. Nevertheless a great majority of crystals are neither perfect nor ideally mosaic. Until now for them there are no other way except for application of the kinematical theory with extinction correction. But this approach is really adequate only for crystals where the Int (hkl) of the most strong Bragg reflections are not less than 80-90% of Kin (hkl). However the integrated intensities of a lot of practically important crystals are essentially smaller than Kin, often in these crystals Int(hkl)/Dyn (hkl) is not more than 3-5 and correspondingly, Int (hkl) / Kin (hkl) is less than 0.1 -0.3. The goal of the present work was to characterized the structure perfection of this kind of crystals. For ihe interpretation of experimental intensities obtained in symmetrical Bragg case was to modify the standard dynamical theory formulas as follows: Int (hkl) = | Dyn (hkl) / P] * [R* /R], R1 = R(g / P), where Dyn (hkl), R and g are computed after W.H. Zachariasen ("Theory of X-ray diffraction in crystals", N.Y., Wiley, 1945), and P - empiric parameter, being = {l=[S(hkl)/D]2j-0.S where S (hkl) - the extinction length and D - mean coherence domain dimension in ') . 4 . • , f i POSTERS PROPERTIES OF CEMENTED CARBIDE WITH DIFFERENT Co CONTENT AND DIFFERENT CRAINS SIZE OF TUNGSTEN CARBIDE FOR CONSTANT MEAN I FREEPATH R. Porat, I. Gavish Iscar, Israel The aim of the project was to investigated the mechanical properties such as hardness TRS nad fracture toughness of different compositions of cemented carbide from the group of material related to die ISO K-35 application. The composition has been prepared with a different cobalt content, different grain size in the way that the composition of the finished sintered product will show mean free path of the cobalt in the range of 5 \xm. The possibility to control the mean free path of the cobalt in the composition besides the different cobalt content and the different grrain size is by preparing the material in different milling time to get different starting point of the tungsten carbide grain size. The mean free path of the cobalt is related to the cobalt content and the specific area of the tungsten carbide grain size. In this case changing of the surface area and the cobalt content could help us to reach the constant value of the mean free path. Normally the same mean free path will show the same hardness and the same fracture toughness. We investigate all these different possibilities to see if can get optimum properties. Wli prepared the following procedure according to the required properties. We mill different compositions composed on WC + TaC/NbC + Co. The reason is to add to the composition small amounts of TaC/NbC is to reach uniform structure and to eliminate grain growth. This was especially needed while we increased milling time which could cause the un-uniform structure and grain growth. For this experiment we prepared 4 basic compositions composed on WC + TaC/NbC + Co as follows: Compositions wt% WC wt% Co wt% TaC-NbC We av. grain size Jim (raw material) A 88 12 2 5 B 88 10 2 5 C 90 8 2 5 D 90 8 2 9 The different materials A B C D have been prepared in different milling time to get different wide range of X (mean free path of the cobalt). The thickness of X has been calculated from the equation combining the coercive force, volume of the coblat and the grain size of the tungsten carbide. The material has been pressed and sintered and the mechanical properties have been measured such as hardness, T.R.S. and fracture toughness. Summarizing the result we found optimum mechanical properties in the following composition: 10% CO + 2% TaC/NbC + 88% WC. In this project we shall show the relation between mechanical properties, composition structure and grain size. ii. ASSESSMENT OF FATIGUE LIFE OF ALUMINIUM ALLOY COMPONENTS WITH CRACKS USING RANDOM LOAD MONITORING SYSTEM R. Arone, Sh. Ustilovsky, G. Sharshukov, A. Loksh, L, Potepun Israel Institute of Metals, Technion R&D Foundation, Technion City, Haifa 32000, Israel A stochastic approach describing fatigue crack growth under random loads and incorporating the closure concept for assessment of load interaction effects is presented. Two extreme loading histories are considered: (a) The superposition of overloads, random in time and magnitude, on base-line constant-amplitude cyclic loading, and (b) Random sequence of load peaks. In the first case the model is based on presentation of the delay time due to retardation effects associated with the overloads as a purely discontinuous Markov process. A numerical procedure developed is based application of Kolmogorov-Feller integrodifferential equation. An expression for failure probability is derived. In the second case the load peaks are considered as a sequence of equally distributed noncorrelated random variables. The crack opening stress, determined for an arbitrary i th cycle, is estimated on the basis of the highest maximum and the lowest stresses observed through n preceding cycles. It is shown that in this case some characteristic integral of crack length is normally distributed. Numerical procedure developed accounts for stochastic nature of both the load and the material. In order to verify the model a computerized system for monitoring of simultaneous propagation of random arrays of fatigue cracks has been developed. The panel-type sheet specimens with two rows of single edge cracks (a row on each side) comprising up to 14 cracks (7 on each side) has been used. Constant amplitude cyclic tests performed with the above arrays allowed to evaluate stochastic parameters of material characteristics governing the crack propagation. I 1-1.4 , SOURCES OF ACOUTSTIC EMISSION IN AL-LI BASE ALLOYS Si AND THEIR VARIATIONS WITH HEAT TREATMENT F. Zeides, 1. Roman The present report describes acoustic emission study of two Al-Li alloys. Al-Li alloys are candidates for advanced structural applications, especially in aircraft and aerospace | industry. For this reason intensive development efforts are under way in several ',v countries. The present work employed acoustic emission (AE) studies, as an important support to traditional metallurgical analyses. Ae was registered and monitored during either tensile or compression tests. It has been found that there are two major sources of i AE in the studies alloys, namely, plastic deformation activity and constituent particles failure. Both origins are sensitive to the heat treatment conditions, so that AE may be j££ used as a macroscopic tool for microstructural evaluation. . ;•• « SELF- STRENGTHENING OF THE STAINLESS-STEEL UNDER SHOCK LOADING E. Zaretsky Pearlston Center for Aeronautical Studies, Department of the Mechanical Engineering, Ben-Gurion University of the Negev, POB 653, Beer-Sheva, 84105, Israel The shock induced martensite formation in "marageing" and "marageing"-type alloys is well-known phenomenon, e.g. 11], In the present work the behavior of stainless steel (of 321-iype) near its dynamic fracture threshold at room temperature and shock induced formation of martensite at temperatures from - 40°C up to - 100°C were studied. The velocity interferometer (e.g. [2]) was used for determination of dynamic mechanical properties (Hugoniot elastic limit - HEL, shock viscosity, spallation strength, elasto- plastic transformation hysteresis etc.) of shocked 10-irun width 100-mm dia stainless steel samples. The shock (plane impact) was generated by the impact of 3-mm width steel impactor accelerated by 57-mm-dia powder gun up to velocities 80-500 m/sec. The pre- shoted samples was cooled in situ by soldered copper pipe ring with liquid N2 through disposable rubber pipes. The cross-section of "soft-caught" after impact samples was studied metal lographically. It was shown that the martensite which was formed due the shock induced deviatoric stresses is responsible for stainless steel HEL and spallation strength growth almost in two times. The metallographica! studies of soft-caught samples showed a decrease of martensite transformation starting point from - 60°C in un-shocked samples up to - 20°C in shocked ones. The room-temperature impact experiments show an unknown anomalous growth of stress-strain hysteresis at the impact velocities of about 80-100 m/sec which is close to the stainless steel fracture threshold of 130-140 m/sec. A model capable of explaining both the phenomena is suggested. It based on dynamics of low-energy (10-50 mJ/m^) stainless steel stacking faults. It is shown that the process of voids nucleation due the reverse dislocation reactions with the Frank loops generation and their following coagulation is more realistic for the spallation fracture explanation than the mechanism based on dislocation absorption by micro-cracks [3]. By the simultaneous analyses of both present work experimental data and open literature findings the significant role of partial dislocation motion accompanying the stacking faults reproduction, growth and interaction is shown. In spite of comparatively low stacking fault energy the proper alloying of the material aimed at shock fault formation in every plane of crystal lattice may lead to sufficient growth of its dynamics strength. 1. Chang S-N, Meyers M A Martensitic transformation induced by a tensile stress pulse in Fe-22.5 wt% Ni-4 wt% Mn alloy, Acta Metallurgica, 1988, 36, 1085-1098 2. Barker L M, Hollenbach R E Velocity interferometer for surface of any refractory, Journ. of Appl. Phys., 1972, 43, 4669-4675 3. Tong-Yi Zhang, Li J C M Interaction of a Screw Dislocation with an Interface Crack, Journ. of Appl. phys., 1991, 70, 744-751 PI .(. DISLOCATION SOURCES IN SHOCK DEFORMATION OF METALS $ E. Zaretsky Pearl ston Center for Aeronautical Studies, Department of the Mechanical Engineering, Ben Ciurion University of the Negev, POB 653, Beer-Sheva, 84105, Israel The mechanisms of high-strain-rate (with rates about 10s - 109 sec1) plastic deformation j are not clear as yet; even in the simplest situations. For example, during the plane impact :; a high-speed transition from initial "one-dimensional stress" state to the final situation of • "hydrostatic compression" takes place. The high-speed relaxation of deviatoric stress occurs immediately behind the shock front [1]. The known attempts to describe this relaxation in terms of solid-state dislocation theory were unsuccessful by the following reasons: H 1. The existing dislocation concentrations in pre-strained material and the highest possible 4i dislocation velocities during the deformation (both being the factors of strain rate) are ^l; not enough for quantitative agreement with experimental data [2]. In addition, the ;;. shock-loading behavior of both initially dislocation-saturated and dislocation-free Tj materials are very similar. • 2. Explanations including the processes of dislocation nucleation of multiplication are more successful from the point of view of the strain rate description. However, they ' lead to two or three orders of magnitude surplus in dislocation concentration at the > final stage of the stress-relaxation process. To overcome this contradiction one need an additional artificial assumption of simultaneous nucleation of opposite-sign dislocation [3] (annihilate during final stages of the shock loading). The recent pulse X-ray diffraction measurements of structure variations of solids under ^ shock loading |4| lead to better understanding of the stress relaxation mechanism. The '••-' lattice stacking faults (SF) bounded by the partial dislocation (PD) are responsible for this relaxation and almost all shear deformation in stacking faults. The present work suggest a new theory of dislocation multiplication under effeci of shear j stress generated immediately behind the shock front. The theory based on the analyses of PD motion under shear (deviatoric) stress effect, i.e. bow-out of pinned partial segment to half-loop, stretching of its lateral branches and these branches collapse with forming of new PD loop (bounding SF fragment) and a pinned half-loop ready to new act of reproduction. The theory allows to estimate the rise time of a shock front, the residual post-shock temperature and to predict elasto-plastic and fracture behavior of shocked metal. v* 1. Swegle J W, Grady D E Shock Viscosity and the Prediction of Shock Wave Rise W Times. Journ. of Appl. Phys., 1985, 59, 692-701 %. 2. Johnson J N Constitutive Relation for Rate-Dependent Plastic Flow in Polycrystalline m Metals. Journ. of Appl. Phys., 1969, 40, 2287-2293 §; 3. Meyers M A A Mechanism for Dislocation Generation in Shock-Wave Deformation. ps Scripta Metallurgies 1978, 12, 21-26 |3 P 4. Zaretsky E B X-Ray Diffraction Evidences of Stacking Faults Role in Plastic j$ Deformation of Solids under Shock-Wave Loading Shock Waves, 1993 (accepted for publication). I'l .7 LOCAL REINFORCEMENT OF METAL CASTINGS WITH CERAMIC FIBRES /PARTICLES B. Barkai, N. Kami Israel Institute of Metals, Technion Research and Development Foundation, Ltd., Haifa Israel Metallic composite materials (MMC) are increasingly occupying an important position in modern industry. Including of ceramic fibres or particles in the metallic matrix produces a material with improved properties, such as hardness and resistance to abrasion, as compared with the matrix material. Local reinforcement of castings permits utilization of the advantages of MMCs confines to the regions where the particular product requires them while leaving intact the desirable properties of the base metal, e.g. machianability and ductility, over the rest of the product. This paper summarizes a number of research projects carried out by the authors in the courses of the past few years and dealing with the development of preparation methods and the investigation of the properties of aluminium and zinc alloy castings reinforced with alumina fibres or silicon carbide particles. The reinforcement fibres are introduced into the metal as a mass of compressed fibres (preform), which contains about 20% fibres and 80% air spaces. The reinforced portion forms an integral part of the casting. From metallographic observations made in the boundary zone, metal/MMC, it became clear that the microstructure of the metal remained unaffected by the contact with the reinforcement fibres, while no clear dividing line was formed separating the metal from the MMC in the boundary region. There is good penetration of the metal into the air spaces between the fibres; all the spaces are filled with mertal, so that close contact has been established between the metal matrix and the fibres. Silicon carbide particles were introduced by a similar method. In research carries out by the authors the investigation focused on the possibility of placing the mass of fibres in different areas of the casting. The results showed that the penetration of the metal into the interstices between the fibres was good and independent of the location of the fibre preform in the casting. Hardness tests of the specimens of alumina fibre reinforced aluminium matrices showed that the MMC regions of the specimens tested as cast are very hard as compared with the areas of the rest of the metal. Tensile tests were made with specimens taken from the cast part in such a manner that they contained, at their centre an MMC aera and, at their ends (where they held by the tensile machine) - metal only. The results of these tests point to a lower fracture stress and a reduced ductility a compared with specimens consisting only of metal. An examination of the fracture face under a scanning electron microscope (SEM) showed that in all the specimens the fracture occured in the boundary region between the metal and the reinforcement layer. In specimens of a zinc alloy matrix with silicon carbide reinforcement the changes in properties exhibited similar tendencies. Comparative wear tests showed that reinforced matrix specimens withstood abrasion better than unreinforced matrix specimens. ]'\ . FORMATION OF Co AND Ta SILICIDES ON Si (100) AND Si (111) SUBSTRATES FROM CODEPOSITED Co AND Ta FILMS S. Darwish and J. Pelleg Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel The silicides are used in the microelectronic industry as interconnecting lines and as contact material. The silicides have low resistivity and they are characterised by good thermal stability. In ternary systems of refractory metal - near noble metal - and silicon (in some experiments the substrate is the third component, i.e., silicon) after annealing at temperatures above 700°C disilicides are usually on the top of this layer. The near noble silicide near the silicon substrate is used as shallow contact, and the refractory silicide on the top of this layer p protects this contact. The low resistivity of the near noble silicide, and the high thennal stability of the refractory silicide make such a system valuable in the semiconductor industry. In this work we investigated the formation of cobalt and tantalum disilicides from co-deposited film of Co and Ta by electron gun deposition on silicon substrates N-type <100> and <111> to a thickness of 1500 A. The formation investigated at temperatures range 700-1000°C by hot X-ray diffraction (in situ) and rapid thermal annealing (RTA). The phases indetification was done by the above techniques. The difference in the rates of formation of the silicides was observed between phases on Si <100> and <111> substrates. No reports on the Co-Ta-Si system were yet published. PROBABILISTIC PROCESSES AND FORMING STRUCTURE DURING SOLIDIFICATION D. Kopeliovich It is known, that distribution of defects in a metal product has a probabilistic character, that results in statistical description of its quality (durability, reliability). However solidification, which considerably determines formation of these defects, is usually being described by deterministic ways. It makes difficult to prognosticate distribution of defects. In this work a probabilistic concept of solidification has been developed. It is proved that solidification parameters (cooling rate, temperature gradient, solidification rate etc.) are random magnitudes. Role of fluctuations in selforganization during solidification is considered. The probabilistic concept has been used for developing imitative models of solidification. Two kinds of model are developed. The discrete model simulates a wide range of structures: from monocrystal to amorphous. The continual model considers transferprocesses which take place in the transient zone of crystallization. A further imitative model is for the simulation of forming dendrite. This model is based on the assumption of a random character of supercooling. It yields branchy structures that become more even as local negative supercooling gradient decreases. The probabilistic concept has been used for creating the method of prognostication of A - segregation in steel ingots. The method allowed to prevent appearance of this segregation in critical points of the nuclear power plants. Influencing of cooling rate and chemical composition upon dendritic structure parameters was investigated by experiment. An experimental set up for influencing upon solidification by means alternating electromagnetic field has been designed. it 1M . If) INFLUENCE OF GRAIN BOUNDARY SEGREGATION ON THE THERMOPH YSIC AL PROPERTIES OF CERAMICS x Tatiana Gambaryan, Efim Ya. Litovsky and Michael Shapiro Faculty of Mechanical Engineering, Technion - Israel Institute of Technology Haifa 3200, Israel i Heat transfer in porous ceramics is accompanied by diffusion of various kinds of impurities, normally present in all crystalline materials. These impurities tend to concentrate (segregate) from the bulk onto surfaces of small pores, existing in the region separating two sintered crystalline granules. Under the influence of an externally applied temperature gradient the impurities diffuse in the bulk and along the pores' surfaces. These diffusion-segregation processes are accompanied by heat release and absorption, occurring on the opposite sides of the pores. These processes are shown to affect the temperature field near the pore and, hence, the effective thermal conductivity of ceramic materials. A simple model of heat transfer in porous ceramics in the presence of segregation-surface diffusion mechanism is proposed. The effective thermal conductivities of materials possessing a small amount of spherical or cylindrical pores are calculated, which are shown to generalize the well known Maxwell formula for conductivities of composite materials. Nondimensional parameters are formulated which govern the relative influence of segregation and diffusion of impurities on the effective conductivity of porous materials. Estimates performed for several Arrhenius type surface isotherm formulas, relating surface and bulk concentrations of impurities, show that the segregation-diffusion mechanism satisfactorily describes abnormal temperature dependences of thermal conductivities of refractory oxides in vacuum. However, for atmospheric pressure the effect of this mechanism is dominated by gas conductivity in pores. Analyses of influence of grain boundary segregation-diffusion processes on the thermophysical properties of ceramics possessing various compositions and microstructures were performed. It was shown that this mechanism is most significant for temperatures exceeding 1500°C and for measurements in vacuum in the temperature range from 400 to KKXTC. ; 'i. i:' TEMPERATURE AND GAS PRESSURE DEPENDENCES OF THERMAL CONDUCTIVITY OF DENSE AND INSULATING CERAMIC MATERIALS E. Ya. Litovsky, M. Shapiro Faculty of Mechanical Engineering Technion-Israel Institute of Technology, Haifa 32000 Porous ceramics and refractories are widely used in metallurgy, insulating constructing materials, space technology, high-temperature furnaces, etc. Operating conditions of such materials cover wide ranges of temperatures (T), pressures (P) and gas compositions. Investigation of thermal properties of ceramics are essential in designing and optimization of various high-temperature aggregates and materials, possessing predetermined thermal properties. Analysis of experimental data are presented, which where obtained for thermal conductivities X(P, T) and thermal diffusivities a(P, T) of high temperature oxide ceramic materials with porosity 5-98%, obtained for temperatures 5OO-25OOK and gas pressure 1()-2 - 2 • 107 Pa. These results reveal several abnormal effects in behavior of X(P, T) and a(P, T), which can not be explained on the basis of known classical mechanisms of heat transfer in porous materials, the latter include heat conduction in solid and gas phases, radiation and gas convection within the pores. It was found that X.(T) exhibits complicated nonmonotonic behavior. This contradicts the results of classical experimental investigation of X(T) for dense crystal ceramic materials which decrease with increasing temperature (Eiken's law). The latter dependence was not observed for porous materials in rarefied gases. The dependence of X.(P) and a(P) upon the gas pressure at high temperatures is qualitatively different from that observed for low temperatures. In particular, it was found that a(P) increase with decreasing gas pressure. For insulating refractories thermal conductivities was found to be complicated function of porosity, pores and particle sizes. The above effects are qualitatively explained by a combination of the classical and new heat transfer mechanisms, related to heterogeneous heat and mass transfer process occurring at the grain boundaries of dense ceramics, and heat radiation scattering for insulating refractories. The novel heat transfer mechanisms include segregation-surface diffusion of impurities along grain boundaries and pore surface and gas transport, arising from chemical conversion in pores. Analysis and classification of the pressure-and temperature dependences of thermal conductivity for various refractories and ceramic materials on the basis of the fractal model of porous materials structures and the above mentioned heat transfer mechanisms. Pressure- and temperature dependences of thermophysical properties of dense refractories i. i i I SYNTHESIS OF IRON, NICKEL AND COBALT TITAJVIDES FROM FINE t ELEMENTAL POWDERS I ''' E. Paransky, I. Gotman and E.Y. Gutmanas I- Department of Materials Engineering, Technion, Haifa, Israel Iron, nickel and cobalt titanides were synthesized from consolidated to full density micron size elemental powder blends (Fe, Ni, Co-Ti). Consolidation was performed by cold sintering (high pressure consolidation at ambient temperature) at pressures considerably lower than those required for consolidation to full density of the prealloyed intermetallic powders. Subsequent homogenization heat treatments resulted in solid state reactive synthesis of the corresponding titanides. Synthesis of a titanide of the final stoichiometry was accomplished through the formation of intermediate Fe, Ni, Co-Ti phases of different stoichiometry, and its kinetics were controlled by the diffusion of components through these phases. Reactive diffusion processes in Fe, Ni, Co-Ti powder systems were studied on model structures - a Ti foil partly or fully embedded in a Fe, Ni or Co powder and, vice versa, a Fe, Ni or Co foil/thin sample embedded into a Ti powder. Based on the model experiments, the synthesis heat treatment parameters were chosen. The effect of processing parameters on the microstructure and mechanical properties (hardness, yield strength at elevated temperatures) of obtained titanides was investigated. X-ray diffraction, SEM/EDS and TEM/EDS employed for microstructural investigations showed that the titanides obtained had very fine homogeneous microstructure with micron/submicron grain size. Solid-state reactive synthesis from elemental powder blends may be used for production of close to net shape full density titanide intermetallic parts. l'l . 14 DEVELOPMENT AND CHARACTEREA1TONS OF COMPOSITE SOLID ELECTROLYTE FOR BIPOLAR LITHIUM BATTERIES FOR ELECTRIC VEHICLES E. Peled and D. Golodnitsky Our goals are to develop and characterize a small laboratory prototype of a new bipolar lithium battery for electric vehicles and energy storage. This rechargeable battery consists of thin foils (about 10-5011 thick) of lithium anode, composite solid electrolyte (CSE) or composite polymer electrolyte (CPE), composite cathode and bipolar Ni based current collector. This paper describes materials fabrication and evaluation for the CSE, CPE and the composite cathode. Our CSEs and CPEs mechanically stable, have very good compatibility towards lithium, good ionic conductivity (10"5 - 10"3 ohm"1 cm1 at 110°C), low and stable interface lithium/CSE resistance (10-50 ohm cm2 at 120°C for up to 1000 hi). The conductivity of our CSEs and CPEs at high salt concentration is one to two orders of magnitude higher than the state of art polymer electrolytes. For some compositions the lithium transfer number is closed to 1. Several Li/CSE batteries were cycled (charge-discharge) for over 60 times. CAPACITORS WITH GRAIN BOUNDARY BARRIER LAYER MICROSTRUCTURE IN THE BaO - (SrO) - TiO2 AND BaO - SnO2 -TiO2 S YSTEMS V. Stancovski, M. Kravchik, A. Goldstein, A. Bar Israel Ceramics and Silicates Institute, Technion City, Haifa The fast miniaturization of electronic circuits requires the development of capacitors with high volumetric efficiency. In the case of the lower operating voltages, grain boundary barrier layer capacitors, utilizing very thin dielectric layers, are of great interest. Grain boundary layer (GBBL) microstructures are characterized by semiconductive grains enveloped by insulating layers. At the macroscopic level, this results in an effective dielectric constant 1-3 orders of magnitude higher than the intrinsic dielectric constant of the material in question. The traditional synthesis of GBBL devices, involves a iwo stage sintering process: the first stage is a reduction, followed by controlled cooling down to room temperature. Semiconductive pellets are obtained at this stage of the process. A chemical treatment has to be done in order to provide the dopant ions involved in the formation of the barrier layers at the level of grain boundaries. The formation of the GBBL microstructure is achieved by a second thermal treatment, under oxidizing conditions. A single stage process, which does not involve a complicated chemical treatment of the reduced pellets and is compatible with the multilayer technique, is presently being investigated. The processing conditions, regarding parameters such as: composition of ceramic powders, atmosphere conditions and thermal treatment schedules, are examined. I'l . If; i EFFECT OF HEAT TREATMENT CONDITIONS IN ALUMINIUM - MATRIX COMPOSITES C. Alexandru*, P. Moldovan* and G.V. Ghica** *Department of Science and Eng., Polytechnic Institute, Splaiul Independentei, nr. 313, Sector 6, Cod. 77206, Bucharest, Romania **INTEC - SA Bucharest, Romania The purpose of the present study is to examine the role of the heat treatment conditions on the microstructure and microhardness of the paniculate reinforced Aluminium-matrix composites. The composites containing up to 20 vol. % A12O3 and SiC particles, was processes via a molten metal mixing route and then cast, heat treated in various conditions. The microstructural development during heat treatment was studied using optical and Scanning Electron Microscopy (SEM). The microhardness results were plotted against aging time, at a different temperatures, to obtain the aging curve. PI . I 7 INSITU QUALITY MONITORING TECHNIQUE FOR A HIP PROCESS O. Tevet*, O. Yeheskel**, V. Atzraony**, and M.P. Dariel** "Nuclear Research Center, P.O. Box 9001, Beer-Sheva, Israel 84190 *Ben Gurion University of the Negev, Beer Sheva, Israel Hot lsosiatic Pressing (HfP) is one of the most important processes in powder metallurgy. In this process powder of the material, enclosed in a canister, is simultaneously subjected to high pressure and high temperatures during a certain period of time. Due to this treatment the material is densificd. The details of the process regime strongly depend on the specific material and are usually obtained alter a costly and long procedure. A possibility to monitor the quality of the material during the densification process wili help to save time and money. Herewith a technique for insitu monitoring this quality is described. It is based on a sound wave velocity measurements of the material during the process. Comparing Ibe sound velocities in the material to the velocities expected in a fully densified sample under the same conditions (reference velocity) gives an indi :alion lo the material quality. In order to derive the velocity in the material one has lo divide the longitudinal dimension of the material by the "time of flight" of Ihe sound through it, which is the value measured by the technique. This dimension changes during the densification process due to both the change in the material density and the canister deformation. In the present work methods lo predict the dimension changes during the HIP process arc shown. Also arc discussed the theoretical based methods to derive the reference sound velocities under the process parameters from known values under other conditions. This technique enables a modification of the Ashby's densiticalion prediction model as will be shown. Results of applications of this technique during real HIP processes will be given. IM . I li MICROSTRUCTURAL EVALUATION OF CAST ALUMINIUM ALLOY MATRIX COMPOSITES P. Moldovan*. C. Alexandra* and G.V. Ghica** *Department of Science and Eng., Polytechnic Institute, Splaiul Independentei, nr. 313, Sector 6, Cod. 77206, Bucharest, Romania **1NTEC - SA Bucharest, Romania Aluminium alloy matrix composites with A1203, SiC and Graphite participates were synthesized using liquid metallurgy route. The microstructure of the composites were analysed using optical, Scanning Electron Microscopy (SEM) and energy dispersive microprobe (EDX). Several phenomena which influence solidification in unreinforced casting are modified in the presence of high volume fractions of the reinforcing phase. The evaluation of matrix structures was influenced by particle segregation due to settling, particle-solidification front interactions and interfacial chemical reactions was discussed. The nucleation of primary silicon on ceramic particles in AlSi matrix composites is widely observed. In the presence of magnesium there is a relatively high probability that the graphite particle surface will be suitably oriented, with respect to silicon, to form a iow energy interface with it and act as substrates for heterogeneous nucleation. PI . 19 UNUSUAL MECHANICAL PROPERTIES OF HIGH-STRENGTH ROLLED STEEL WITH MACROANKOTROPIC STRUCTURE P.D. Odessky, S.I. Morozov, M.R. Uritsky, A.B. Steblov and V.T. Chernenko Currently available on a commercial scale is hot-rolled steel strengthened in a special chamber-type installation directly ahead of the runoff table, the heat treatment consisting of surface cooling at rates as high as ~ 1000°C/s using turbulent water jets. Then the metal is tempered on the runoff table at the expense of heat accumulated in the axial zones. This rolled stock is made of conventional low-carbon or low-alloy structural steels used in mass production. The surface layers (up to 1 mm) acquire the structure of tempered martensite, whereas the core has the structures formed on diffusion type y-» a transformation. The result is structural macroanisotropy over the cross-section of steel. Normally, the hardness of surface layers exceeds that of the core by = 100 HV. The residual compression stress in the surface layers is as high as <= 100 N/mm2. The yield strength of steel is in the range from 350 to 630 N/mm2 depending on steel composition and cooling conditions. The property levels given above are average values and actually vary, for instance, in 2 2 angle steel with 8 mm flange as follows: ay = 560 N/mm , au = 660 N/mm for the 2 2 overall cross-section ; ay = 600 N/mm , au = 685 N/mm for 3 mm thick test pieces cut 2 2 from surface ; Oy = 455 N/mm , ou = 520 N/mm for the core zone. The peculiar protective effect of the more compressed higher strength surface zones by structural macroanisotropy is often responsible fo the unusually high mechanical and performance properties of rolled stock. MAGNETOCHEMISTRY OF THE TETRAHALOFERRATE (III) IONS IN THE A3Fe2X9 SERIES Roey Shaviv*, Richard L. Carlin** *TAMI (IMI) Institute for R&D P.O. Box J0140 Haifa Bay 26111 Israel **Department of Chemistry The University of Illinois at Chicago Chicago IL 60680 USA The magnetic properties of the tetrahaloferrate (HI) ions at elevated temperatures are paramagnetic and straightforward as expected from the 6A1 ground state with S = 5/2 in a (quasi) octahedral symmetry. At lower temperatures (below 10 K), where superexchange interactions become dominant, these materials tend to order as antiferromagnets. Specifically, for compounds of the stoichiometry A3Fe2X9 where A takes the form of |4-Y(py)H|+ (X = C1-, Br-; Y = H, CJ, Br; py = pyridine) the symmetry the ferrate ion is subjected to deviates from that of a perfect octahedron and the small unisotropy which results gives rise to spin canting in the magnetically ordered phase. The extent of short range magnetic ordering in these series appears to be dependant on Y whereas the critical temperature appears to be more strongly dependent on X-. Single crystals of several compositions in this series were studied by XRD, ac magnetic susceptibility, and calorimetric experiments. The results of these experiments will be presented and the magnetochemistry of the series will be discussed. Acknowledgement: This work was performed at the University of Illinois at Chicago and was funded by the National Science Foundation (USA) under DMR-8815798. STRUCTURE AND PROPERTIES OF RAPIDLY SOLIDIFIED GOLD - TITANIUM ALLOYS T. Aboud and D. Shechtinan Technion, Israel Institute of Technology Department of Materials Engineering, Haifa 32000, Israel This study concerns the development of rapidly solidified dilute gold alloys with a view to producing enhanced mechanical properties that should prove beneficial to the jewellery industry. Four alloys were melt spun: 1 wt.% Ti, 2wt.% Ti, 3wt.% ti and 5wt.% Ti. On etching polished cross-section in Aqua-regia all of the melt spun alloys were found to show transitions in structure associated with a change in: (a) solidification rate, (b) response to etching, (c) preferred orientation, (d) phase transformation and (e) grain size. It was found that (Ti) content causes a change in the ribbon formation mechanism; their sponsor is shown to be critically dependent on the thermal conductivity of the specific alloy. Two classes of TEM studies had been individually on flat-on and cross-section samples. The first is on regions of alloy which were electron transparent directly after melt spinning without further thinning being required, whilst the second is on alloys which were thinned subsequent to rapid solidification and hence are more representative of the bulk of the alloys. In accordance with, the microstructures observed by SEM and the phases detennined by X-ray diffraction (for both sides); full matching had been reported by the later class. The microstructures of the rapidly solidified dilute Au-Ti alloys and their response to post solidification heat treatment is discussed with reference to their mechanical properties. The properties of the as-solidified and heat treated alloys are shown to be determined by the solute content critically dependent on the degree of super saturation achieved and the size/morphology/density of precipitates presents. As predicted by rapid solidification theory, it was observed that the pre-mell spun alloys showed a highly segregated microstructure; whilst for the melt spun alloys a high degree of super saturation have been achieved. Enhanced mechanical properties have been achieved and the active hardening mechanisms are found to be solution hardening and precipitate hardening. I MICROSTRUCTURAL AND COMPOSITIONAL CHARACTERIZATION OF i TiW/AI-0.8%Si/TiW/PtSi/(100)Si a j A. Ashkenazi*. Y. Komem* and I. Lerner** I *Department of Materials Engineering, Technion, 32000, Israel •National Semiconductor, Migdai Haemek, 10566, Israel The microstructure and composition of a contact, composed of an outer layer made of (30nm) TJ3W7, an intermediate layer of (550nm) AI-0.8%Si, a diffusion barrier layer of (90nm) T13W7, and a platinum silicide layer (about 50 nin thick) as an interconnect to the (100) Si substrate, were studied after heat treatments at temperatures between 400 and 5(KrC. The contact microstructure was characterized by X-ray diffraction, Auger Electron Spectroscopy, Electron Microscopy and Secondary Ions Mass Spectroscopy. Special attention was given to the study of the correlation between the stability of the layered structure and the electrical properties of the contact, such as sheet resistance and contact resistance. It was discovered that the contact microstructure was not stable during the heat treatments, and diffusion processes of Al, Ti, W and Si are taking place. The first species to diffuse are Ti and W, from the inner and the outer TiW layers, at 400°C. This process is followed by some solid state reactions that create aluminide phases like AI3TJ, Al^W and AJ5W. At 475°C, the inner TiW diffusion barrier layers fails and Al starts to diffuse through it into the silicide layer. Consequently Al decomposes the PtSi layer and reacts ' with Pt to form the Al2Pt phase. The formation of this phase is followed by volume increasing which causes an upward bending of the inner TiW layer and fonnation of cracks. Total decomposition of the PtSi layer is found at 525°C and enables diffusion of Si from this layer into the Al layer. The microstructural changes during the heat treatments, like decrease in the Al layer thickness and formation of new phases with high resistivity like AI5W causes an increase in the sheet resistance. The replacing of the PtSi/Si contact by the Al2Pt/Si contact which has a lower Scholtky barrier height cause a decrease in the contact resistance. At 55O°C the contact fails as a result of A] .spike formation in the Si substrate. I k £ UTILIZING ACOUSTIC - EMISSION AS A NON - DESTRUCTIVE METHOD FOR I PRESSURE VESSELS f A. Mittelman \ School of Applied Science ' Hebrew University Jerusalem There are several Non Destructive Testing (NDT) methods that are employed in engineering applications and industry for quality control examination. It is well known that each method has its advantages and disadvantages. The mode of decision regarding NDT inspection in critical engineering components is generally based on correlation of NDT data from at least two independent methods. In this article the implementation of Acoustic Emission (AE) as a NDT method tat found to be much more reliable, simple to analyze and easy in utilizing than Ultrasonic (US) and X- ray for an industrial problem will be shown. The paper will apply to a problem in the field of pressure vessels. Pressure vessels were generally examined non destructively by using US and X-ray. In some vessels the indications of the US were indeterminate and in the X-ray were negative. The quality control authorization required that the results of the two methods will have negative results. The US results indicated that there might be a problem but the X-ray indicated that the vessels are okay. Analyzing the AE activity of those vessels during proof tests gave clear results in sorting the vessels. Monitoring and analyzing the RMS (root mean square) of the AE enabled us to distinguish between sound and defected vessels. The separation was conducted by ' monitoring the AE activity from the onset of loading. It was found that the degree of severity of the defects in vessels affect the AE activity already in low load levels. P] .24 i Au-Cu-Cd ELECTROPLATED ALLOYS STRUCTURE AND MECHANICAL If, PROPERTIES > S. Libov, Eva Igner f Jotaly Ltd. Electroplated gold alloys have a great importance in electronicjewellery and other industries. The binary system Au-Cu is well known in the literature and a large number of papers deal with it, whereas the ternary system Au-Cu-Cd is much less known. Cd has a great influence on the mechanical (physical) properties, colour and structure of this alloy. Au-Cu-Cd system is the subject of this presentation and the results obtained are discussed. The mechanical properties such as hardness, plasticity and physical properties such as _ density were measured and studied. The structure of these deposits were investigated using X-ray diffractometry. Au-Cu-Cd deposits give the X-ray spectrum of FCC lattice where Au and Cu are oriented according to the Bravais type lattice and Cd is presented as a defect in the vacancies or in the grain boundaries. X-ray analysis of the Au-Cu-Cd deposits show an asymmetrical broadening of the main line peaks which eventually is eliminated after the annealing heat treatment. Since the background is constant in both spectra (before and after the heat treatment it can be assumed that Cd and the vacancies move into the grain boundaries in the low temperature state. This assumption is supported by the fact that the deposit density does not change as well as its microscopic structure as illustrated in the SEM pictures and EDS analysis. The mechanical properties are changed significantly by the heat treatment e.g., the deposit becomes less brittle - plastic and hardness is also decreased. •* This investigation shows that by choosing the adequate deposit composition and by performing the optimal thermal treatment the desired mechanical properties can be obtained. PROCESSING OF A HIGH - PURITY ALUMINA MATERIAL O. Glozman, L. Baum, W.D. Kaplan, and D.G. Brandon Dept .of Materials Engineering, Technion-Israel Institute of Technology, Haifa, Israel Alumina is possibly the most intensely studied ceramic system. Despite the vast amount of published work, every alumina powder has to be studied and adapted to specific and available equipment. The primary objective in the sintering of high-purity polycrystalline alumina is to maximize the material density, while preventing abnormal grain growth, The purpose of the current study is to optimize the processing of high purity alumina powders into a high density product. Several powders of commercial alumina were tested: the specimens were prepared by filter-pressing of aqueous slips. Low viscosity and high solids content slurries were prepared and optimized by latin squares analysis. A dense green compact was formed, by controlled rate filter pressing. The final sintered density was, as expected upon the initial green density of the specimen. Pre-coarsening treatments and the effect of sintering rate were also examined. Preliminary experimental results will be reported. PI.26 THERMOMECHAN1CALLY STRENGTHENED SHAPES FOR BUILDING STRUCTURES MADE OF LOW-CARBON AND LOW-ALLOYED STEEL A. Klyuch Department of Materials Engineering, Technion, Israel Inst. of Technology, Haifa 32000 Thermal strengthening of steel shapes made from low-alloyed and low-carbon steel during their hot rolling seems to be of the most effective technologies. The production of such a metal is implemented in industrial conditions for the following kinds of shapes: angles, I-beams and channels. The main stage of the process is interrupted quenching with the following self-tempering. A heterogeneous microstructure is formed in the cross-section of the shape. The metal has a structural anisotropy and could be assumed as a composite material. One of the most important tasks of the research was to find a possibility of application of such a material in welded metal structures. For this reason the studying of these steel shapes has been performed both for the as-received condition and after welding. The rolled metal possesses a high homogeneity of its mechanical properties. For example for the 100 x 100 x 10 mm angles made of low-carbon steel yield stress ay = 460 MPa and the standard deviation Soy = 16 MPa. The resistance of the investigated material to brittle fracture is extremely high, e.g. U-notch Charpy impact toughness at temperature minus 70°C for the 75 x 75 x 8 mm angle made of low-carbon steel is 1.36MJ/cm2. The simultaneous increase in strength and fracture resistance should be explained by the presence of specific multilayer microstructure. PI .27 PERFORMANCES AND WEAR PHENOMENA OF THE TiN-COATED TWIST DRILLS Dan Mean, Ladislau Kerekes, Mariana Carean Technical University of Cluj-Napoca, Bd-ul Muncii 103-105, 3400, Cluj-Napoka, Romania One of the most serious problems in today's industry is the improvement of productivity. This is reflected by an important increase in the use of numerically machine tools and flexible manufacturing systems. Consideration has to be given to developing tools with longer life. The TiN-coated tool has great potential for improving the performance of manufacturing systems. The paper presents a comparative experimental study of the performances of conventional HSS drills and TiN-coated drills during the drilling of austenitic stainless steel. The results obtained revealed a great difference in performance between uncoated and TiN-coated drills; TiN-coated drills showed much superiority. The comparison of the axial forces and torque showed that using TiN layers, the decrease of the forces is about 5-8%, and of the torque about 15-20%. The average tool life of the TiN-coated drills was almost six times longer than the tool life of the conventional HSS drills. The microscopy of the tool surface showed that TiN-coated drills didn't present craters and built-up edges, but some cracks were observed running parallel to the cutting edge. Titanium coatings, due to their low friction and small thermal conductivity, act improve tool performance by reducing adhesion and lowering the wear of the tool surface. PI .28 j i SOLID STATE AMORTIZATION OF Cu-Ti-B POWDER SYSTEM BY I MECHANICAL ALLOYING f M. Savransky, S. Berger and B.Z. Weiss | Dept. of Materials Engineering, Technion, Israel Institute of Technology, Haifa, Israel A mixture of elemental powders of copper, titanium and troron was mechanically alloyed for the purpose to study the mechanism of solid state amorphization. Three different compositions and various milling times for each composition were applied. The microstructural, compositional and surface morphology changes occured during the MA were investigated by Scanning Electron Microscopy, Transmission Electron Microscopy combined with Energy Dispersive X-ray Spectroscopy, X-ray Diffraction and Differentia! Thermal Analysis. It was found that two amorphous alloys were formed as the result of MA. Both alloys are composed of only two elements Cu-Ti. However, the first alloy contained mainly copper while the second contained mainly titanium. The amorphous phases were dispersed homogeneously in the powder system surrounded by nano-crystalline grains of copper and titanium. The microstructure of the boron grains was not affected by the mechanical alloying and no interaction between boron and/or copper and/or titanium was observed. The quantity of the amorphous phases increased with increasing milling time until a steady state was reached. The increase of copper in the system from 60wt% to 80wt% lead to a decrease in the quantity of amorphous phase. In the system containing 95wt.% Cu no amorphous phase was observed. The enthalpy change associated with the crystallization of the amorphous phases was measured and correlated with the microstructural changes. STUDY OF CHEMICAL VAPOR INFILTRATION PROCESS FOR SiC MATRIX COMPOSITES i : N. Nawi, D. Itzhak, U. Admon and M.S. Dariel I Nuclear Research Center-Negev and Ben Gurion University ^ Ceramic Matrix Composite materials are well known for their high strength-to-weight ratio and fracture toughness. Conventional techniques for the fabrication of ceramic composites, such as sintering and hot pressing, involve mechanical stress and chemical damage to the fibers. One of only a few processes to fabricate ceramic composites without chemically or mechanically damaging the fibres is C.V.I (Chemical Vapor Infiltration), which is directly derived from C.V.D (Chemical Vapor Deposition). CVI and CVD allow the formation of complex geometries and produce very high melting point materials at medium and even low temperatures. Current isothermal commercial CVI processes suffer from major problems such as surface sealing, slow densification and density gradient in the product. Temperature gradient, forced-flow CVI1"3 reduces the infiltration time and the density gradient significantly. In this process efficiency of infiltration and yield are limited by (a) residence time (inversely proportional to gas velocity), (b) reaction rate (proportional to temperature in the MTS system), (c) unhotnogeneous gas flow distribution and susceptor configuration, (d) blocking of infiltration through formation of impervious internal layers in early stages of infiltration and by extraneous growth of deposits on the surface of the preform. The following is a preliminary report of CVI experiments, performed on graphite fiber preforms under the following conditions: graphite fibrous preforms were retained within a graphite holder in contact with a water-cooled metal gas distributor, thus cooling the bottom and side surfaces of the substrate. The top of the fibrous preform was exposed to the hot zone of a graphite susceptor which resulted in a thermal-gradient of up to 2500°C/cm in the preform. The reactant gases, MTS (methyltrichlorosilane - Ar as a carrier gas), H2 and Ar passed through the cold portion and towards the hot portion of the preform, where they decomposed, to form SiC matrix: CH3SiCl3 (MTS) = SiC + 3HC1 (Excess H2, Ar) HIGH TEMPERATURE PERICLASE INSULATION I. Yaniv, R. Cytermann, T. Litovsky IMI (TAMI) Institute for Research & Development Ltd ' One of the basic requirements expected from technical processes-especially high- temperature processes-is the rational application of energy. Therefore, development of high refractory insulating materials for applications at up to 2000K is of importance for engineering and technology. This work is concerned with the development of high temperature insulation technology on the basis of high purity periclase by the foam method. The high melting point of MgO and the availability of raw materials in Israel nidke this technology economically feasible. The main objects in technology development were creating an optimal material structure corresponding to minimal thermal conductivity and insuring high strength at low reheat change at elevated temperatures. Two basic practical requirements for high-temperature heat insulating materials were used: the porosity should be as large as it possible and the pores should be as small as possible. In order to achieve the desired properties the following technological investigations were carried out: optimization of conditions for initial material preparation, mixing conditions, foam formation and drying and sintering conditions. The technology developed allows to obtain a porous material structure with a porosity in the range 60-80% and particle size 1-10 \xm. Material strength is related to the porosity which in turn, may be adjusted by the process. The particle size distribution provides for large scattering of heat radiation and, as a result inhibits increase in effective thermal conductivity at high temperatures. As a result of performed investigation the technological parameter permitting to obtain high-temperature heat insulation on the basis of MgO with predetermined properties were found. PJ .31 INTERNAL RESIDUAL STRESSES AND WEAR RESISTANCE PROPERTIES OF COMPOSITE NiCr ELECTROCHEMICAL DEPOSITS S. Eskin, O. Berkh, J. Jahavi, J. Lanfir, L. Zevin Wear resistance, microhardness and residual strains and stresses of Cr-Al2O3 and CrNi- AI2O3 electrodeposited composite coatings were investigated as a function of AI2O3 concentration in electrolyte and deposition current density. Composite coating were produced from electrolyte on N, N-dimethylformamide base. For codeposition corrundum particles (a- AI2O3) were used with average particle size of 5 |J.m. Wear rate was estimate as a result of mass loss with sliding distance. Worn surfaces were examined by means of microscopic observation. As shown minimum wear rate was achieved at AI2O3 amount in electrolyte of 15-110 g/1. In the absence of particles the wear rate was 4 time of minimum wear rate. The increase of AI2O3 amount up to 150 g/1 resulted in 3.0-3.5 fold reduction of wear resistance. Microhardness of composite Cr and CrNi coatings did not exceed 650-750 HV and actually did not depend on AI2O3 content X-ray technique was used for determination of residual strains and stresses. Corrundum particles actually served as sensor for these measurements. Good precision in lattice measurements (~110"4) was obtained. Lattice constants "a" and "c" of hexagonal corrundum decreased with increase of particles amount in solution. At particle content about 240 g/1 lattice constants approach those of the free powder. Residual strains in direction normal to the sample surface were calculated as £2 - Ac/c, where Ac is reduction of lattice constant (c). The value of £2 ~ 2-10"3. The further calculation of residual stresses was based on AI2O3 particle location in three dimentional stress field. It was revealed that residual stresses reduced as AI2O3 particle content increased and current density dropped. Wear behavior of composites is discussed in terms of their residual stress condition. PI .32 QUANTITATIVE NON - DESTRUCTIVE LAYER - BY - LAYER ANALYSIS OF THE SURFACE SUB - REGION OF SOLIDS BY EPMA A. Berner Dept. of Materials Engineering, Technion-Israel Institute of Technology, Haifa, Israel A new method for non-destructive quantitative control of element content depth distribution in submicron surface layer of solids has been developed. The method consists in electron probe overvoltage variations for Electron Probe X- Ray Microanalysis (EPMA) and measurements of characteristic X-ray radiation intensity. The connection between the dependences of X-ray production I(E) and element content depth distribution C(z) is define by an integral equation. The concentration depth profile C(z) can be obtained by the measurement of I(E) and the solution of the given integral equation. The correction method is based on a X-ray production depth distribution function derived within the framework of the two-flux presentation of electron-solid interactions. The main advantage of this approach is that without any extra assumptions or simplifications, it can be effectively applied to a system with an arbitrary form of C(z). The method allows for the determination of composition and thickness and of thin submicron films on substrates and element depth distribution, in a non-destructive manner. The thickness of analysed layers can be from 50 nm to several micrometers. Depth resolution in layer-by-layer analysis may range from 8 to 80 nm. Errors of content determination are equal to 5-10% rel. The method was applied to the analysis of thin films of Si-Ge on Si substrates as well as to element content depth distribution control in some amorphous alloys and ion doped samples. The results obtained by this method are in good agreement with Auger Electron Spectroscopy and Secondary Ion Mass Spectrometry results. p 1.3 3 EDS AND X-RAY DIFFRACTION STUDY OF TERNARY ARTIFICIAL SUPERLATTICES I. Goldfarb, E. Zolotoyabko, A. Berner and D. Shechtman Technion-Israel Institute of Technology, Haifa 32000, Israel Artificial superlattice attract a great attention due to the possibility of "tailoring" unusual properties on interfaces with reduced dimensionality. Applications were found in mirror production for soft X-ray and ultraviolet radiations. The preparation of conventional flat superlattices involves an alternating deposition of components providing control of layer thickness on atomic level and absence of interdiffusion at the interfaces. New advantages arise when wedge-layered superlattice are prepared. For example a set of the samples with continuously varied concentration of the components can be produced simultaneously. This set may be used in order to investigate various properties as well as the phase diagram of multi-component systems. Here we present the results of X-ray diffraction (XRD) and Energy Dispersive Spectroscopy (EDS) of wedge-layered Au-Ag-Cu superlattice, produced by means of magnetron-sputter deposition. EDS has been carried out with 5 KV accelerating voltage using Au M Ag L and Cu L radiations. Quantitative results were obtained using conventional ZAF correction and the observed compositions were compared to the theoretically expected from the geometry of sputtering set-up. The correlation was rather good, giving correlation factors 0.95-0.99. X-ray diffraction patterns of all as-deposited samples revealed satellite-like structure of (11 l)-peaks, providing an evidence of the composition-modulated artificial superlattice formation. The experimental spectra are well described in a frameworks of kinematical theory for imperfect superlattice. The computer simulations have demonstrated extremely high sensitivity of the fitting procedure to the fluctuations AH/H of the superlattice period H. As a result a rapid, non- destructive and simple method of AH/H determination is proposed. PI.34 i PREADHESION LASER SURFACE TREATMENT OF COMPOSITE POLYMER, POLYMERS AND METALS ADHERENDS M. Rotel*, J. Zahavi,* A. Buchman**, H. Doduik** *Israel Institute of Metals, Technion City, Haifa 32000, Israel ••Materials and Processes Department, Rafael, P.O. Box 2250, Haifa 31021, Israel Proper surface treatment of an adherend is among the decisive factors with respect to the final quality and durability of an adhesive joints. Various surface treatments are practiced for plastic and metals among them abrasive treatment, chemical treatment and plasma etching. Excimer laser surface treatment presents a new technology for preadhesion treatment of various adherends such as aluminum alloys, thermoplastics and composite polymers. This method presents an alternative for the use of ecologically unfriendly chemicals involved in conventional pretreatments such as anodization and etching. Experimental results indicate that preadhesion laser surface treatment improve significantly strength of aluminum specimens bonded with rubber modified epoxy compared to untreated and anodized substrates. Also adhesion shear strengths of Polycarbonate, polyetherimide and composite adherends are improved compared to untreated or abrasive treated substrates. Optimal laser parameters (intensity, number of pulses) depends on treated materials. The mode of failure changes from adhesive to cohesive depending on laser parameters. Morphology changes ans chemical modification are responsible for the improved adhesion. I PI .35 LASER PL ANARIZATION S. Tamir, J. Zahavi*, Y. Lemer** **National Semiconductors T.T.D, Migdal Haemek, Israel Thin film interconnection technology is becoming very important as the density and speed of semiconductor devices continue to increase. High speed signal propagation is achieved by increasing film thickness and decreasing of line width. These demands lead to sever step coverage problems over high aspect-ratio metal lines and viaes which result in a poor electrical resistance and low reliability of the integrated circuit. One of the solution for filling the viaes is a planarization process using a laser which operates in a pulse mode. Laser irradiation of aluminum metal lines for a very short time cause to a local heating and melting of the metal. The molten metal flows into the via and filled it with the metal. In this work we studied the mechanism of via hole filling using an excimer laser operating at a pulse mode. Pulse duration is 24 nsec and laser wavelength is 193 nm. The beam was directed in perpendicular to a sample of chip which was obtained in its final stage of production or after metallization and before etching. The specimens were irradiated in a vacuum chamber at a total pressure of 1.5-10"6 Torr. The laser energy was concentrated in order to increase the energy. Via holl filling was obtained at laser energy higher than 1 J/cm2 in both kind of specimens, however better results were found at irradiation of chips which were in a stage after metallization before etching and patterning of the metal lines. Quantitative analysis of the filled via showed that aluminum and silicon concentration was the same as the aluminum matrix at laser energy range of 1.7 J/cm2 keeping the underlayer film not affected. Scanning Electron Microscope (SEM) observations showed that the filled viaes were smooth but there were some morphology changes in the aluminum metal. The details of results and mechanism of via hole filling will be presented in the paper. PI. 36 DURABILITY OF GLASS FB3RE REINFORCED CEMENTITIOUS COMPOSITES WITH DIFFERENT LOW ALKALI / LOW LIME MATRICES A. Bentur*, K. Kovler* and I. Odler** •National Building Research Institute, Technion-Israel Institute of Technology, Haifa Israel **Technical University Clausthal, Germany In recent years considerable effort has been directed at the research and development of new glass fibre reinforced cement composites intended for replacement of asbestos- cement, as well as to generate new materials of improved properties, in particular toughness. However, due to the high surface area the fibres are sensitive to interfacial effects with the matrix, which can be chemical or physical in nature and beneficial or deterious from the durability point of view. In the present work three low alkali/low lime cements were developed (Phosphate, Glass and Aluminum Phosphate cements), which have the potential for providing high durability composite. The ageing performance of composites of these matrices, reinforced with E-glass fibres, was studied. The considerable difference in the ageing performance of E-glass composites with different cementitious matrices could be observed and accounted for on the basis of microstructural and chemical effects. In the case where chemical attack and microstructural densening was eliminated (Phosphate cement composite), loss in microstructural densening was eliminated. In composites where the chemical attack was severe (Portland cement) and compounded with microstructural densening (Aluminum Phosphate cement), the durability performance was poor. In the case the Glass cement composite, where microstructural densening was eliminated and the chemical attack was rather mild, the loss in mechanical properties over ageing might be considered as tolerable. These results clearly prove the hypothesis that by adjusting the composition of the matrix, there is a potential for developing high durability fibre cement composites. PI. 37 (j CORROSION AND STRESS CORROSION CRACKING BEHAVIOR OF AISI 304 I AND AISI 316 STAINLESS STEELS IN 55% LiBr It< Ofira Elias*, Irit Lev*, David Itehak* and Pnina Peled** I *Department of Materials Engineering, Ben Gurion University of the Negev, f Beer Sheva, Israel **The Bromine Compounds Ltd., Israel The corrosion and stress corrosion cracking (SCC) behavior, of AISI 304 and AISI 316 stainless steel in LiBr environments, was investigated. U-bend tests, constant load tests, potentiodynamic polarization and open circuit potential measurements, were performed. The experiments were carried out in 55% LiBr environment at temperatures of 60-140'C and pH ranging from 6 to 11.6. It was found that AISI 304 and AISI 316 stainless steels are sensitive to SCC in 55% LiBr environment at temperatures higher than 80°C within the pH ranges of 6-11.6. AISI 316 shows higher resistance to SCC in this environment. Transgranular fracture was observed in the constant load tests, exhibit transgranular and ductile fracture, while AISI 316 failed in a mixed transgranular -»intergranular —> ductile fracture. Both stainless steels exhibit active passive behavior in the tested environments. PI. 38 THE INFLUENCE OF ELECTRON IRRADIATION ON ADHESION OF METAL FILMS Sara Stolyarova ELTAM Technology Inc. Ltd., P.B. Box 600, Haifa 31000, Israel The effect of electron irradiation on the adhesion of silver and copper films to vacuum- cleaved LiF and silica-based glass substrates have been investigated. The samples were exposed to high energy pulse irradiation: E = 3.5 MeV, f = 1.72 Hz, the density of electrons per pulse - 7-109 el/cm2. Doses varied from 1012 to 1010 el/cm2 (102- 109 pulses). The films 350 nm thick were deposited by thermal evaporation. The adhesion strength was measured by direct technique. Fracture surfaces were studied by the use of transmission electron microscope. Three schemes of experiment were used. The first scheme served to reveal the role of type and density of point defects created in substrates by electron irradiation. For this purpose the substrates were irradiate throughout, the bulk density of point defects was measured by spectrophotometer and after that the substrates were cleaved in vacuum directly in metal vapor stream. The fresh, free from contaminants contact of the metal film with the surface enriched with point defects was formed in this way. The nonmonotonous dependence of the adhesion strength on the irradiation dose was observed for both types of substrates. It was shown that the formation of simple point defects (F-centers) in the substrate enhances the adhesion of the films whereas the appearance of defect aggregates leads to adhesion failure at high irradiation doses. The second experimental scheme included direct irradiation of substrate surface in air before film deposition and allowed to study the effect of radiation induced chemical reactions with the environment on the adhesion strength. This kind of treatment has shown opposite effects in LiF and glass. The adhesion strength of silver film on LiF dropped while that in glass substrate increased significantly. In the third scheme the irradiation of the already prepared film-substrate contacts was studied. In this case the irradiation led to adhesion failure of Ag films both for LiF and glass substrates due to blistering effects ans reaction product formation at the interface. Basing on this studies the optimal conditions for adhesion activation have been found and the physical models for the effects observed have been proposed. THE EFFECT OF FREQUENCY IN PLASMA MATERIALS PROCESSING A. Raven*. A. Bettelheim**, J.E. Klemberg-Sapieha**, L. Martinu** and M.R. Wertheimer** *NRC-Negev, Division of Chemistry, P.O. Box 9001, Beer Sheva 84190, Israel **"Groupe des Couches Minces" (GCM) and Department of Engineering Physics, Escole Polytechnique, Box 6079, Station "A", Montreal, Quebec H3C 3A7, Canada The advantages of low pressure plasma over conventional processing techniques are well known. In view of certain distinct advantages of "high" frequency (microwave, 2.45 GHz) than "low" frequency (0.5 or 13.56 MHz), two particular material processings were studied [1-3]: (i) surface nitriding of a/(3 titanium alloy by nitrogen or by a nitrogen mixture with hydrogen, and/or argon, (ii) deposition of diamond-like carbon (DLC) in methane, methane-argon or methane/hydrogen mixtures. It is shown that "high" frequency plasma affects in more pronounced way the fragmentation and the creation of more species with high excitation potentials than the "low" frequency, as well as the characteristic microstructure, composition and formation rate. For the nitriding process, it was observed that nitriding of Ti-6A1-4V (a + P structure) at higher frequency increases the phase content of e and a' phases and decreases the 8-phase content. Nitriding of Ti-8Al-lV-lMo (a structure) at higher frequency result in an increase of a'-phase content and a decrease of e-phase content; whereas the 8-phase content remains constant. For the deposition of DLC, it was observed that the higher frequency results in more hydrogen bonded to the films with a higher deposition rate; whereas, ion bombardment at the surface enhances reactions in the gas phase and results in hard (about 30-48 GPa), low stress (about 0.5 GPa), and thick 3-10 |im) films containing 20-30 at.% of hydrogen. The effects of the plasma excitation frequency on processes in the plasma bulk and on the structure and properties (phase formation, formation rate, lattice parameters, hardness, wear and density) of the nitrided layers and of DLC films are presented and discussed. 1. A. Raveh, G. Kimmel, R. Avni and A. Grill, Advances in X-Ray Analysis 13, (1990) 129-135. 2. A. Raveh, R. Avni and A. Grill, Thin Solid Films 186, (1990)241-256. s 3. A. Raveh, L. Martinu, J.E. Klemberg-Sapieha, and M.R. Wertheimer. J. Vac. ;j Sci. Technol. A10, (1992) 1723-1727. $ P! .40 THE POSSIBLE USE OF MIXED IONIC ELECTRONIC CONDUCTORS, INSTEAD OF ELECTROLYTES, IN FUEL CELLS I. Riess, Physics Department, Technion IIT, Haifa 32000, Israel Mixed ionic electronic conductors (MIECs) are considered for replacing pure ionic conductors i.e. solid electrolytes (SEs) in fuel cells (FC)'. It is shown that an electronic conductivity that originates from a change in stoichiometry under reducing or oxidizing conditions at th electrodes, can be tolerated provided the FC is operated close to its maximum power output. Thus a MIEC can replace a SE in a FC that is intended to operate under those conditions. The operating conditions in the electrolysis process of water are different. Under these conditions MIEC cannot replace a SE. The analysis leading to the acceptance of mixed conductivity suggests also that electrodes can be prepared by stoichiometry or by doping of the surface region of the SE or MIEC used. The stoichiometry change and the doping will turn the surface regions into semiconductors which can serve as electrodes. The use of a protective thin SE layer on a MIEC is analyzed. It is not needed for a FC operated under maximum power output condition. It may, however, be useful for low power operation conditions and for electrolysis. 1. I. Riess, Solid State Ionics 52 (1992) 127. PI.41 FRACTURE OF CARBON FIBRE REINFORCED PEEK UNDER STATIC AND FATIGUE CONDITIONS: THE INFLUENCE OF THE DEGREE OF CRYSTALLINITY * A. Tregub*, H. Harel*. G. Marom* and C. Migliaresi** *Casali Institute of Appl, Chemistry, Graduate School of Appl. Science and Technology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel **Dept. of Materials Engineering, Univ. of Trento, Mesiano 38050, Trento, Italy Recently, our results of a study on the effect of the degree of crystallinity on the mechanical properties and fatigue behaviour of poly(etheretherketon) (PEEK) matrix composites have been reported. That study compared the mechanical behaviour of samples with low (10%) or high (35%) degree of matrix crystallinity, and for different 4 loading angles with respect to the reinforcement direction. It was shown that the degree of crystallinity effect was not confined to matrix dominant loading directions. Rather, % unexpected improvements with increasing crystallinity were observed in the mechanical strength and modulus and in the fatigue life, for fiber governed longitudinal samples. That effect was attributed to the influence of a transcrystalline layer, presumably formed on the fiber surface. It has been shown before that a transcrystalline layer could affect the stress transfer mechanism and reduce the residual thermal stresses. Thereby, its presence •* could improve certain longitudinal mechanical properties. The present study reports the results of a fractographic study performed in order to check the hypothesis on the effect of the transcrystalline layer. For that, the fracture surfaces of h : carbon fibre reinforced PEEK composites (APC-2) samples, failed either statically or by fatigue loading, were studied. The emphasis was laid on the question of how the presence of the transcrystalline interlayer results in a transition from an adhesive failure at . J the fibre/matrix interface to a cohesive failure within the interlayer. The fracture surfaces of longitudinal and transverse specimens of two levels of crystallinity, namely, of the as received material (35%) and of a thermally treated quenched material (10%), after static, fatigue and impact 3-point bending, were studied » by scanning electron microscopy. The fractography revealed different extents of matrix j, - material adhered to the fiber surfaces, depending on the degree of crystallinity and on the testing mode. In general, however, the fibres in the fracture surfaces of the lower fci crystallinity materials were mostly exposed, whereas those of the higher crystallinity p\ materials were covered by matrix debris bonded to the fibre surfaces. The presence of ' matrix fragments on the fibres implies that in the higher crystallinity material the fibre j forms a stronger bond with the matrix, probably through a transcrystalline interlayer, ~ within which fracture ultimately occurs. The paper discusses the mechanical strength, the fatigue behaviour and the fracture properties of the composites in terms of specific potential contributions of the transcrystalline interlayer. 1. \ PI .42 RAPID THERMAL ANNEALING OF HIGH DOSE ARSENIC-IMPLANED SILICON E.N. Shauly* ** and Y. Komem** •Department of Diffusion/Ion Implantation - National Semiconductor - Migdal Ha'Emek, 10556, Israel. **Department of Materials Engineering, Technion, Haifa, Israel. A scaled CMOS technology requires shallow source and drain (s/d) junctions. Junctions depths for 0.5 \x CMOS technology are approaching 100 nai or less, to prevent punchthrough and short channel effect for the N+/p s/d regions. Rapid Thermal Annealing (RTA) provides a promising technique to minimize the displacement of ion implantation impurities while activating impurities and annealing implantation damage. In this work the effect of RTA on the diffusion, activation and clustering was studied in (100)Si after implantation at different doses by resistivity measurements (Rs), Secondary Ion Mass Spectroscopy (SIMS), and by Spreading Resistance Analysis (SRP). The ranges of the implants doses was 3.29 x 1015 to 8.20 x 1015 [cm"2] with energy of 60 KeV. The RTA temperatures were between 980c and 1200c and times from 1 to 300 sec. For comparison hot-wall furnace annealings were performed at 900c and 550c for 2h and 30 min respectively. A computer model was developed to predict the maximum activation of the electrically active implants. The effect of implantation dose, the RTA time, and the RTA temperature at different conditions, was compared with the computer modeling. It was found that for the RTA higher does leads to lower Rs and deeper junction depth (Xj). However, after hot wall furnace annealing higher dose led to higher Rs. Longer RTA time decreased the Rs and increased Xj. Higher temperature improved the Rs due to less clustering effects. The work was sponsored by National Semiconductor, Migdal Ha'Emek, Israel. •f i CHARACTERIZATION OF THE IMPLANT ENERGY DISTRIBUTION OF HIGH CURRENT BF2 IMPLANTS INTO (001) Si N. Bacharach**, E.N. Shauly* **, Y. Komem** and Y. Avrahamov* *Department of Diffusion/Ion Implantation - National Semiconductor - Migdal Ha'Emek, 10556, Israel. **Department of Materials Engineering, Technion, Haifa, Israel. In the fabrication of p+/n-junctions in CMOS application, the use of BF2 as the implanted species instead of boron has become very common. The additional fluorine causes the amorphization of the implanted silicon substrate. When the implanted specie is boron, there is no amorphization. Amorphization reduces channeling effects and enabling shallower junctions for demand of higher gate densities. BF2 has been implanted using a high current implanter into (001)Si substrate. The implant does was in the range 3-4.3 x 1015. Different acceleration and extraction voltage ratios were used. Some of the implanted samples were annealed using Rapid Thermal Annealing (at one step at 1100c or two steps of 600c + 100c) and others were annealed in a hot-wall tube (at one step at 950c or two steps at 550 + 950c). The profiles of the fluorine and boron were measured by SIMS after implantation and after annealing treatments. Sheer resistance was measured after annealing. It was found that dissociation of BF2 ions occur during implant. The dissociation effect increases as the ratio extraction/acceleration voltage decreases. The dissociation level were calculated for different ratios. The effect of the ratio on the sheet resistance were also studied. The work was sponsored by National Semiconductor, Migdal Ha'Emek, Israel. f A COMPARISON OF TCA (TRICHLOROATHANE) AND DCE (TRANS 1,2 DICHLOROETHLENE) - GROWN OXIDES ON SILICON E.N. Shauly* **, R. Mor* and Y. Avrahamov* *Department of Diffusion/Ion Implantation - National Semiconductor - Migdal Ha'Emek, 10556, Israel. **Department of Materials Engineering, Technion, Haifa, Israel. In most VLSI processes, chlorine is introduced into the oxidation ambient to improve both the oxide and the underlying Si properties. The most popular chlorine sources are HCI, TCE or TCA. TCA has recently been identified as an ozone depleting chemical since it is very stable, and DCE was proposed as an alternative. DCE and HCI are substitute chemicals for TCA, but DCE is superior in performance to corrosive HCI. Process change from TCA to DCE need full checking of the process kinetics as well as the device characteristics. A comparison of TCA and DCE was made considering the following aspects: oxidation rate for the growth of thin oxides (<350A) using Nicollian-Reisman power law, oxide thickness for all CMOS oxidation processes, fixed oxide charge Qf, mobile ionic charge Qm, and C-V shifts for 1000A oxide. Breakdown voltage, leakage current, life time evaluation and yield results were compared using capacitors, SRAM and Answering Machine micro-processor using 1.0 Ji CMOS (Twin Well) technology that ran with TCA or DCE. It was found that oxidation rate with TCA and DCE have the same Nicollian-Reisman kinetics constants. All the CMOS processes grew the same thickness (within 3a). The C-V results show the same Qm levels where the average Qf is 35% less for the DCE oxide. Breakdown voltage, leakage current, life time evaluation tests and yield were comparable for the two chlorine sources. The work was sponsored by National Semiconductor, Migdal Ha'Emek, Israel. PI .45 INVESTIGATION OF THE ACOUSTIC FIELD GENERATED BY REACTIVE SPUTTERED ZnO LAYERS IN ACOUSTO-OPTIC DEVICES, BY MEANS OF X-RAY DIFFRACTION E. Jacobsohn. E. Zolotoyabko and D. Shechtman Dept. of Materials Engineering, Technion-I.I.T., Haifa 23000, Israel. ZnO films have aroused increasing interest lately due to their potential use in electrooptic and acoustooptic devices. There is a growing interest in using the silicon as a substrate since silicon technologies are highly developed. The advantage of such a use is in the possibility of integrating electrooptic and electronic devices on a common substrate. In the current investigation ZnO (1 |*m in thickness) was reactively sputtered on top of an SiO2 layer by dc magnetron gun. The films were deposited at power levels ranging from 100 to 250W. The gas mixture contained O2 with partial volume ranging from 20% to 80% at total pressure of 3-10 mtorr. The influence of the deposition parameters on the structure orientation and stoichiometry of the ZnO film was determined by means of AES, XRD, SEM and TEM. It was found that the O2 partial pressure has a crucial effect on the microstructure crystallographic orientation and stoichiometric properties of the ZnO film. SAW devices were then made. The acoustic field of the devices were studied by electrical measurements as well as by means of in situ X-ray diffraction. A new approach for probing acoustic field in acousto-opti'cal devices based on dynamical X-ray diffraction is demonstrated. The experimental results as well as the advantages of the method are discussed. PI. 4b f ' IN SITU X-RAY DIFFRACTION DURING THE FORMATION OF TiSi2 C49 K FROM Ti-Si MULTILAYER ON Si(100) d ?, J. Sariel* and H. Chen** * *Nuclear Research Center Negev, POB 9001, Beer-Sheva 84190, Israel. ', **University of Illinois at Urbana Champaign, Dept. of Mat. Sci. and Eng., ; 1304 W. Green St., Urbana, IL 61801, USA. Si and Ti multilayers transform at high temperatures (above 700°C) to TiSi2-C54. This phase is important for microelectronic applications because of its low resistivity, stability up to 900°C and compatibility with silicon processing. However before this phase is formed, an unfavourable metastable TiSi2-C49 phase is already formed at lower temperature. The kinetics of the transformation of TiSi2-C49 phase can be characterized as a process of nucleation and growth, using the well known Johnson Mehl Avrami (JMA) equation: f = 1 - exp (-ktn) where k - the rate constant t - the reaction time n - Avrami exponent In the present work the transformation of a multilayer of Si and Ti to the C49 phase is studied by in situ X-ray diffraction. Isothermal annealing in vacuum was done at four different temperatures, 270^, 290oC, 300°C and 310°C. A position sensitive detector (PSD) was used to collect the diffracted beams of (060) and (131) peaks, during the annealing time. From the plots of Ln(Ln(l/(I-f))) as a function of Ln(t), for each temperature, the Avrami exponent, n, was determined: n = 2.0 ± 0.1 The rate constant, k, is a function of the temperature, according to the equation: k = k0 - exp (-Q/RT) where ko - pre exponent Q - activation energy •( R -gas constant T - temperature By measuring the transformation isothermally at several temperatures, deriving k at each temperature and drawing Ln(k) as a function of 1/T the activation energy of the transformation, Q, was found to be: Q = 2.5 eV These values of Q and n were comparable to the values found by others in the literature. f PI .47 PREDICTION AND CALCULATION THE PROPERTIES OF CERAMICS WITH SPINEL STRUCTURE E.N. Men, I. Sinitsky and D.G. Brandon Department of Materials Engineering, Technion, Haifa, Israel. A self-consistent phenomenological scheme (CCM - cluster component method) has been used to describe and predict the crystal chemical and magnetic properties of defect spinels and solid solutions. The central idea of CCM is the relation of structure (including point defects and short and long-range order parameters) with a set of material properties by decomposition of the given solution into its components on the basis of suitable ordered structures in the given lattice. A simple defect spinel y - M2O3 and its solid solutions (1-C) MgQVi/304-c MM2O4 are considered (M1 = Mg, Fe, Zn1 M = Al, Cr, Fc). The influence of composition, defect content, degree of order and partial pressure on the lattice parameters and magnetic properties these spinels was investigated. PI. 48 T S ;-l THE SYNERGICTIC EFFECT OF ENVIRONMENTAL PARAMETERS ON THE i '•! BEHAVIOR OF PLASTIC MATERIAL * R. Huberman, E. Gutman and D. Itzhak Dept. of Materials Engineering, Ben Gurion University of the Negev, Beer Sheva, Israel The behavior of PMMA (Polymethyl methacrylate) and SAN [the random copolymer of styrene (70%) - acrylonitrile (30%)] in water saturated atmosphere under UV irradiation at 80°C was studied. The samples were exposed to the aggressive environments for about 4000 hours. The exposed samples were mechanically and optically tested. It was found that SAN is more stable as compared to PMMA and can be used as glazing materials for the cover of the Heliocol sun light collectors. PI.49 THE EFFECTS OF DOPANTS ON THE DEVELOPMENT OF THE MICROSTRUCTURE IN THIN FILMS OF AI2O3 W.D. Kaplan and D.G. Brandon Dept. of Materials Engineering, Technion-Israel Institute of Technology, Haifa, Israel In order to study the structure of general grain boundaries in alumina, doped and undoped anodic films of alumina were grown on aluminium substrates. The films are produced by the anodization of aluminium in a doped or undoped electrolyte, removal of the amorphous film from the metal substrate, and the subsequent crystallization of the self- supporting sample on specially prepared TEM sample grids. Films of a thickness of the order of 5 nm to 50 nm can be produced. Doping of the anodic films was achieved by adding cations of the desired dopant element to the anodizing electrolyte. The crystallization of the thin films is achieved through heat treatment in air at various temperatures. Above 1250°C, the (X-AI2O3 structure forms, and this was the main phase studied in this work. The purpose of the films was to provide high quality specimens for grain boundary characterization by high resolution electron microscopy (HREM) due to the large number of grain boundaries, and their near-normal orientation to the film surface. However, the introduction of different dopant elements caused changes in the microstructure of the film. These changes include grain size, degree of porosity, faceting of pores and grain boundaries, and changes of the film thickness during the crystallization process. In some cases, the average grain size was found to exceed the film thickness by an order of magnitude. The limitations and possibilities of this sample preparation technique will be presented, as well as preliminary characterization of the dopant-affected microstructure. PI. 50 MICROSTRUCTURAL EVALUATION OF ALIGNED CERAMIC MATRIX COMPOSITES N. Shafry, D.G. Brandon Dept. of Materials Engineering, Technion-Israel Institute of Technology, Haifa, Israel The microstructure of a ceramic composite was quantitatively characterized in order to : determine numerical values for the microstructural parameters which affect the interfacial : shear stress. The fiber diameter and the spatial fiber distribution were determined to characterize the degree of order of the fibers within the composite. ', The material for these studies was a 2-dimensional, SiC fiber-reinforced, glass-ceramic & laminate. . The specimens were polished, optically micrographed, and then lapped and repolished \ and micrographed again, taking the same location to produce a serial section. This •; procedure was repeated for each specimen, removing 25 to 50 |im at each stage. ' The micrographs were digitized using a Macintosh "OneScanner" and image analysis was performed using "Image 1.44" software. Each micrograph, containing over 100 fibers, was analyzed to obtain the diameter of the fibers and their center coordinates. Basic statistics were used to compare the data for single identified fibers through the serial sections and the angle of deviation of the fibers from the direction to the slicing was determined. The results show significant misalignment of the fibers within the composite, as well as other sources of stochastic deviation from ideal architecture. PI .53 I A COMPUTER PROGRAM FOR THE CALCULATION OF ATOMIC POSITIONS ON GENERAL GRABS BOUNDARIES W.D. Kaplan and D.G. Brandon Dept. of Materials Engineering, Technion-Israel Institute of Technology, Haifa, Israel The influence of grain boundaries on the characteristics of polycrystalline materials is important, both from a technological and a scientific point of view. With recent increases in the resolution of high resolution transmission electron microscopes (HRTEM), there has been a marked increase in the number of scientific research programs on the atomic structure of grain boundaries. However, computer simulations of the image must be conducted to understand the HRTEM images. These simulations involve the combination of the crystal (or defect) potential with the contrast transfer function (CTF) of the HRTEM. While a number of computer programs for the simulation of HRTEM images exist, most of these software routines include only the generation of ideal periodic crystallographic structures. The initial determination of atomic positions at defects, such as grain boundaries, requires computer codes of a different nature, which allow for rotation, translation, and varying occupancy over different regions of the crystals to be studied. In order to fulfill these requirements, a computer program has been developed which generates general grain boundaries. The program operates through conversion of the general Bravais symmetry to orthonormal space, and the generation of large simulated bicrystals. (The large size of the bicrystal has been set to minimize edge-effects in the subsequent image simulation programs). The program runs on personal computers, both IBM-PC and Apple Macintosh, and prepares super-cell files in EMS format. Possible uses and limitations of the software program will be presented, as well as a number of examples. PI.52 STRONG ELECTROSORPTION AT THE THIN BISMUTH FILM / ELECTROLYTE INTERFACE A. Bluvstein Advanced Technologies Center, TEMED Industrial Park, 206 Oron Rd, Arava, 86800, Israel Thin bismuth films are relatively new object in electrochemistry. Recently a number of peculiar effects were found at the thin Bi film/electrolyte interface. Surface conductance (SC) vs electrode potential curve qualitatively corresponds to that of semiconductor electrode with minimum at positive charge of the surface. At the negative charges SC can be described quantitatively by the fields effect. At the positive surface charges the SC increase is caused by oxygen electrosorption (for non-adsorbing electrolyte) or by halide chemisorption in the presence of Cl", Br' and I". Besides, halide adsorption results in the negative shift of the minimum of SC vs potential curve, and partial charge transfer upon adsorption rises in series Cl" < Br" < I". Time-resolved SC measurements show that adsorption kinetics obeys the Roginskii- Zeldovich equation. The kinetic parameters are also calculated. It is supposed that SC rise is connected with hole injection into the space charge region of Bi thin film electrode by surface states formed upon oxygen and halide adsorption. PI.53 A METHOD FOR THE MEASUREMENT OF THE THERMAL CONDUCTIVITY C' j TENSOR IN THEM LAYERS OF YBa2Cu3O7 * L. Kornblit, N. Gluzman, M. Auslander * Ben Gurion University of the Negev, Beer Sheva, Israel " A plate of MgO (10 x 5 x 0.5 mm3) is used as a substrate on which is grown a layer of YBa2Cu3O7 0.5 \im thick. The layer of Ba2Cu3O7 is covered with a film of SrTiO3 which must be about 0.005 ^m thick. On this film are vapour deposited a heater/thermometer and a thermometer in the form of two narrow (~ 3 nm) silver strips (thickness 0.3 Jim, : length 2.5 mm) with branches for current and potential probes. The SrTiO3 film isolates the heater/thermometer and the thermometer from the YBa2Cu3O7 layer. •} '•i Calculations show that the components of the thermal conductivity tensor A* (within the thin layer) and X.y (the component in the direction perpendicular to the plane of the layer can be found with the accuracy of ± 5%. P2.1 STRUCTURE OF TiNx NITROGEN RICH FILMS Rafael R. Manory* and Giora Kimmel** •Department of Chemical and Metallurgical Engineering and Microelectronics and Materials Electronic Center, RMIT, POB 2476V, Melbourne, Vic 3001, Australia **Division of R&D N.R.C.N/, POB 9001, Beer Sheva 84190, Israel This paper discusses various defects in TiN and related nitrides and their repair by heat treatments. TiNx thin film received on glass by reactive sputtering under various conditions. X-ray diffraction showed gradual structural changes as a function of the amount of nitrogen. It was clear that the strongest diffraction line was (200) for lower nitrogen contents and (111) for overstoichiometric cases. The structure was imperfect. After heat treatment an almost perfect NaCl structure was formed. P2.2 XRD INVESTIGATION OF CHROMIUM ALLOYED MEDIUM CARBON STEEL X-20 CrMoV12.1 M. Yelin*, P. Yoffe*, S. Libov** *IEC- Materials Laboratory, Haifa **Technion, Haifa Steel X-20 CrMoV12.1 was investigated as a promising heat resistant material. The investigated steel specimen contained 0.18% C, 10.5% Cr, 0.25% V, 0.9% Mo, 0.6% Mn, present as probable carbide generators, with the addition of 0.8% Ni. The steel was investigated at the following states: 1. as received (AR); 2. rolled with up to 30% reduction at 720°C (R); 3. heated at 600°c for 125 hours and coo/ed in air (HT); 4. after high temperature creep testing at 600°C under 20kg/mm^ load (HTC); 5. after exposing during 20 minutes at 1200°, 1250°, 1300°, 135O°C. Lattice strain (LSt) values. Lattice size changes (LSi), Austenite presence and Carbides transformation (CT) were examined and considered. ASTM Data Base was used for phase analyses. a-Iron analytic line width and broadening were measured for lattice parameters. Strain evaluations were made from comparison between XRD spectra for AR sample and the others. The following phase composition peculiarities were obtained: 1. Austenite was not revealed at XRD level for HTC and " 1350" states. 2. All of other states had 1.5-3% vol. austenite present. 3. Dominant kinds of carbides were M23C6 for AR and M7C3 for all other states. 4. The total freo carbide amount is minimum at R state and maximum at "1250". 5. Heating up to t > 1250°C results in Fe-Cr and/or Fe Cr Mo intermetallic compounds. 6. The largest LSt value was 0.303% (Sample "1200"), and the smallest one 0.08% (HTC specimen). A comparison between phase analysis and lattice parameter changes brings one to the conclusion that precipitation of intermetallics ought to unload the matrix twice as small on a micro-strain level. The carbide transformation kinetics model is offered and discussed from the XRD and from the results (of other investigations). P2.4 H YDRCXJEN CONDITION IN MIDDLE CARBON LOW ALLOY BAINITE STEEL: LOCALIZATION, DIFFUSION AND FLAKES GENERATION IN LARGE FORGING Pavel Yoffe Israel Electric Corp. Ltd., Haifa, Israel The common point of view for Hydrogen condition (HC) in steel is absent, and H-Me chemical bonding for 3d-transitive metals is discussed as ls-4s and ls-3d hybridizative INTERACTIONS impossibility at steel making conditions. Energy of H diffusion activation (EAHD) was evaluated at 673K, 973K and 1273K and evaluation results were considerable to show at three types of snares as vacancies, free grain surfaces as threevacancies. The HC notion as free monoatomic flow was adopted and hydrogen embrittlement idea was used for flakes generation description as follows. From called approximation and experiment condition the Fick's equation was decides as integral which was equal to reduced mass of hydrogen. Bymodal form of curves shows that two forms of H were extracted. The literature data of diffusion constants for Fe a and Fe X were used, and for every form Eda were calculated (kcal/g at): 673K - 3.35 and 2.84. 923K - 3.25, 2.84 and 5.45; 1273K - 5.5 and 7.0. The diffusion of two hydrogen forms - unbounced and absorbed by indented atoms - were fixed after comparison famous data and ours. Experiments temperatures and forging cooling condition conformity let to consider the FG next two processes collaborations contemporary: 1. Natural cavity filling by hydrogen up to CRITICAL pressure value (Pc) and superfilling of cavity - "in collector" diffusion (Die). 2. Cavity environment filling by hydrogen up to equilibrium solubility because of opposite (out of collector) diffusion (Doc). The Die reason is concentration gradient and Doc's one - the back osmose, or surplus gas PRESSURE. When Pc > owp or when forging is under abroad load cavity environment might be cracked up to length determined by diffusion way value. The last is snares concentration function and its asymmetry lead to a trim asymmetry. The local hydrogen concentration values were computed from real defects measurements by an equation which let to estimate crack length dislocation density 9 1 = (2.2-10 [H]/d(Ty), where - dislocation density, av - yield point and [H] - hydrogen concentration. The last value relates to domestic (regional) condition and being computed for our results gave data which were in a good accordance OF local mass spectrometry. It is clear of course the local hydrogen embrittlement is probable as a result of hydrogen concentration fluctuation, and crack trim should generate after outer loading. Activation energy of H diffusion calculations and well known data show that during usual technological heatings of investigated steel forging the vacancies left by H at 673K, the free surface - at 973K and threevacancies - at 1273K. The last defects part is not be determining because forged steel has high density as a rule. P2.5 I A NEW METHOD FOR DETERMINATION OF HEAT TRANSFER COEFFICIENTS | IN THE PROCESS OF RAPID QUENCHING OF AMORPHOUS METALLIC f RIBBONS | V. Manov*, M. Geller* E. Broyk-Levinson*, A. Manuchin** }• *Department of Materials Engineering, Technion, Haifa, Israel **Urals Polytechnical Institute, Ekaterinburg, Russia Knowing cooling rate values is of great importance in the rapid quenching technology. Rates of quenching are determined by the heat transfer coefficient between the melt and spinning drum surface during melt spinning procedure. Measuring the temperatures in the melt-drum system is complicated by the great value of the cooling rate (106 K/s). • — A new method for temperature control of rapid quenched melts has been developed. The method is based on the substitution of the real melt spinning procedure by the model one. The model presents a double-layered system with the copper film deposited over the amorphous one by the vacuum evaporation method. The heating of the double layer system is realised by short high-power electrical pulse (1-2 mks). Due to great difference between the two layer resistances, a significant difference arises between the temperatures of the amorphous and copper films. Quartz thin films were deposited on both sides of the | layered system to prevent its oxidation during the rapid heating and cooling. High sensitive photoelements are used for temperature measurements. . s The experimental data are obtained by using the oscillograph and are treated by the ^ equation of heat balance between amorphous film and copper. As was revealed, the value of heat-transfer coefficient is 5-104 W/m2K in the system Fe80 - B20 - Cu, that correlated to melt spinning parameters for above mentioned system. Suggested method of the heat transfer coefficients determination can be succesfully used in the production technology of a new amorphous metallic alloys. P2.7 PECULIARITIES OF GLASS-FORMING CONDITIONS OF INORGANIC, CHALCOGENIDIC AND METALLIC GLASSES V. Manov, D. Shechtman Department of Materials Engineering, Technion, Haifa, Israel Peculiarities of glass-forming of inorganic, chalcogenidic and metallic liquids have been analyzed. Experimental data concerning the structure of liquid and glasses, politerms of viscous flow of glass-forming, values of liquidus temperature TL and vitrification temperature Tg enables the extention of general principles of polymer structure of typical glasses to metallic glasses. The formula for theoretical estimation of the vitrification temperature has been obtained: (EL + 20RTL)ELTL (EL + 20RTL)EL + (EL - RTL)RTLlnf where: EL - activation energy of viscous flow of liquids, - . TL - melting temperature, 1012 Pas - vitrification viscosity value. r , . As have been shown for different glasses, the deviation of Tg ° values from experimental data less then 30K. Conclusion. Correlation between glass-forming principles of inorganic, chalcogenidic \*> and metallic alloys have been carried out. The method of definition of new metallic glasses compositions on base viscous flow values of melts have been suggested and tested succesfully. P2.8 HYDR(XJEN ATTACK ON COPPER AND COPPER-BERYLLIUM ALLOY SURFACE D. Moreno* and D. Eliezer** *NRCN, Beer Sheva, Israel **Department of Materials Engineering, Beer Sheva, Israel The importance of the interaction of hydrogen with metals, alloys and intermetallic compounds in the field of nuclear reactors, permanent magnets, heterogeneous catalysis, powder metallurgy, electrochemical cells etc., has been the subject of considerable research (1-4). The nature of the sample surface and structure, the degree of oxidation and the ease of the chemical reaction in a specific environment, all vary markedly with different materials. Surface interaction is the basic step of degradation in hostile environments like hydrogen, and it is known that the equilibrium surface composition often differs from their bulk in most alloys. Copper and its alloys tend not to form hydrides easily and therefore suitable for use in hydrogen environments. Copper's hydride is very rare (stable only in aqueous solutions), and has a FCC structure which is characterized by very low diffusivity hence the interaction with hydrogen is restricted mainly to the surface. The technical preparation and irradiation procedure for the copper and copper beryllium samples have been reported elsewhere (5-7). A scanning electron microscope was used to determine the surface degradation on the samples. The exposed surface of the charged copper samples revealed different types of degradation dependant on the surface history of the material. The degradation of the sample surface is due mainly to the traces of surface contamination which were coherent with the original surface structure. These traces are mainly the oxides, CuO and CuO2, and surface analysis (Auger) has determined these oxides to be a few nm deep. The enthalpies of formation for CuO and CuO2 are AHf = - 155.2 kJ/mol. and - 166.7 kJ/mol., respectively. These oxides are most probably created during the production of the material, and during charging and dissociation of hydrogen near the copper surface, the most probable reaction is the formation of H2O as in the following reaction: H2- >2H CuO + 2H > Cu + H2O or CU2O >Cu2 + H2O These spontaneous reactions are due to a lowering in the energy, as the enthalpy of formation of one mole of water is - 285.9 kJ/mol, significantly lower than either of the copper oxides. The water formed during the reaction is added to the electrolyte solution while holes and pitting are created on the surface. This reaction does not occur in the copper-beryllium alloy since the beryllium reacts with the oxygen with an enthalpy of formation of - 610.9 kJ/mol, resulting in a very stable oxide and the surface is not attacked. In copper and copper alloys, the degradation is attributed ti the chemical potential of the oxides on the surface, and the reaction of these oxides with hydrogen atoms dissociated in the hydrogen environment. 1. P.B. Viswathan, C.S. Swamy and V. Srinivasan, J. of the Less-Common Metals,163 (1990) 89-108. 2. M.R. Louthan, Jr., G.R. Caskey, Jr., J.A. Donovan and D.E. Rawl, Jr., Mater. Sci. Eng. 10 (1972) 357-368. 3. S. Nakahara and Y. Okinaka, Scripta Met. 19 (1985) 517-519. 4. I.R. Harris, Proc. of 12th Int. Workshop on RETM Magnets and their Application, Canberra, Australia (1992) 347-371. 5. D. Moreno, E. Abramov and D. Eliezer, Scripta Met. Mat. 26 (1992) 277-282. 6. D. Moreno, E. Abramov and D. Eliezer, Scripta Met. Mat. (admitted to be published). 7. D. Moreno and D. Eliezer, J. Material Science Letter (to be published). P2.9 DECAGONAL QUASICRYSTALLINE PHASE IN THE Al - Cu - Co ALLOY SYSTEM B. Grushko, R. Wittmann and K. Urban Institute fiir Festkorperforschung, Forschungszentrum Jiilich GmbH, Postfach 1913, W-5170Jiilich, Germany A thermodynamically stable decagonal quasicrystalline phase was first reported in Al-Cu- Co in 1988 [ 11. In later publications it was claimed that the high-temperature decagonal phase was sometimes replaced by complicated crystalline phases (approximants) during cooling. The effect was interpreted by several authors as the structural instability of any Al-Cu-Co decagonal phase at room temperature. The question of stability plays a crucial role in the discrimination between the current theories of quasicrystals. In order to clarify this question, a part of the phase diagram including the region of the decagonal phase was investigated at temperatures from 550°C up to the melting of alloys [2, 3]. In the present paper a complimentary study of the decagonal phase is presented. The study was carried out by transmission and scanning microscopy, energy dispersive X-ray analysis. X-ray diffractometry and differential thermal analysis. The Al-Cu-Co decagonal phase was found to behave as a stable phase in the studied temperature range. In a wide range of alloy compositions the decagonal phase formed at higher temperatures becomes supersaturated at lower ones as a result of the changes in the homogeneity region. The consequences of this fact and its manifestation in the observed electron diffractograms are discussed. 1. L.X. He, Y.K. Wu, and K.H. Kuo, J. Mater. Sci. Lett. 7, 1284 (1988). 2. B. Grushko, Phase Transitions, in press. 3. B. Grushko, Phil. Mag. Lett., in press. P2.10 SPRAY PROCESSING OF METAL MATRIX COMPOSITES Enrique J. Lavernia Materials Science and Engineering, Department of Mechanical and Aeorospace Eng., University of California, Irvine, CA 92717 Spray atomization and deposition processes provide an attractive means of combining near-net shape manufacturing with the structural control available through rapid solidification. This synthesis approach is currently being studied as an alternative route for the manufacture of highly reactive (i.e., Al, Mg), high temperature (i.e., Ni, Fe), difficult to work materials (i.e., NJ3A1), and metal matrix composites (Al/SiC, Ni3Al/TiB2). During spray atomization and deposition, a stream of molten metal is disintegrated into a fine dispersion of droplets using high energy inert gases. The resultant distribution of micron sized, rapidly quenched droplets is directed towards a substrate, where it impacts and builds up into a compact of predetermined microstructure and geometry. In the present lecture, the microstructures and mechanical behavior of various spray deposited materials elucidated as a function of processing conditions, reinforcement distribution (for MMCs), and alloy chemistry. In addition, the experimental results are discussed and compared to those anticipated from currently available theoretical models, paying particular attention to the synergism between processing parameters and microstructure. P2.11 SOME PRINCIPLES OF CREATION OF PROTECTION STRUCTURES L.I. Slepyan Tel Aviv University, Faculty of Eng., Dept. of Solids Mechanics Mat. and Structures, Tel Aviv, Israel Some principles of the improvement of the efficiency of protective structures under impact or explosion are considered. This can be achieved by the increase of its fracture energy (by prevention of the plastic extension deformation instability) or, in more general case, by optimum design of material properties, for example, by reduction of its extension resistance in the initial portion of deformation curve with its ultimate strength being held constantly. These structures look like a Superplastic Protective Structures (SPPS). The SPPS possess the property to dissipate a lot of energy before it is damaged, along with the capacity to have huge plastic strain. The process of damaging of SPPS is stable in tension; being shocked, they deform but do not break. The SPPS are assembled out of conventional materials, and their unusual behavior is caused by the microstructure, namely, by special ways of elements joining or by geometrical characteristics of the elements. Under normal conditions the SPPS behave as usual rigid materials. Where may the SPPS be used? (i) The SPPS are to used for construction of protective shells in which any dangerous stuff or liquid may be kept and transported. In extreme situations or accidents the tank made up of SPPS can be enormously stretched but remains tight. (ii) Another use of SPPS is the protective shells for atomic power plants, chemical plants, etc., meant to resist possible explosions and to protect environment from pollution and/or contamination. (iii) SPPS can be used as a material for tankers and similar bulks containing incompressible fluids to make all the construction compressible and thus prevent its puncture by shocks. P2.12 IRRADIATION EFFECT ON THE PROPERTIES OF Cu-0.8% Cr ALLOY: POSSIBILITY OF THE SLIGHTLY DOPED Cu-ALLO YS USE AS CANDIDATE MATERIAL FOR THERMONUCLEAR REACTOR DIVERTER PLATES. V.M. Ustinovshchikov*, L.N. Bystrov**, N.R. Bochvar** * Advanced Technologies Center Association, Temed Industrial Park, 1NFODISK TEMED Ltd., (206) Oron Rd.-Mishor Yemin Arava 86800, Israel ** A. A. Baikov Institute of Metallurgy, Academy of Science of Russia, Leninsky prospekt 49, Moscow, Russia Electron irradiation-induced aging of Cu-0.8% Cr alloy was investigated. The experimental conditions were electron energy about 2.3 MeV, dose-up to 2.2 x 1022 nr2, experimental temperatures 15 and 100°C. It was found, that due to irradiation-induced disintegration of supersaturated solid solution alloy electroconductivity and thus, thermoconductivity increased. This as well as rather high mechanical properties enable us to consider Cu-0.8% Cr alloy as candidate material for nuclear reactor diverter plates. P2.13 h CYCLIC IRRADIATION EFFECT ON CREEP BEHAVIOR OF Fe-BASE BCC || ALLOYS. MODEL ALLOYS. ? L.N. Bystrov*, A.B. Tsepelev*, V.M. Ustinovshchikov** i * A. A. Baikov Institute of Metallurgy, Academy of Science of Russia, Leninsky prospekt 49, Moscow, Russia ** Advanced Technologies Center Association, Temed Industrial Park, INFODISK TEMED Ltd., (206) Oron Rd.-Mishor Yemin Arava 86800, Israel Experimental study of cyclic irradiation effect on creep behavior of model Fe-base B.C.C. alloys, viz. Fe-15Cr, Fe-20Cr and Fe-4Cr-4V-4Al (wt.%), has been carried out in the range 200-500°C. It is shown that the cycle mode irradiation leads both to the short-time transient creep (due to dynamic dislocation bias) and the monotonous decreasing of creep rate (because of strengthening caused by radiation-induced solid solution decomposition). 1 P2.14 f REPLICATION MICROSCOPY AND A REMNANT LIFE ASSESSMENT TECHNIQUE B. Feldman, Y. Man and A. Kaufman IKA, Industrial Consulting, Haifa Throughout the world, most fossil electric power plants as well as chemical and petroleum plants have been in operation for long periods of time-so long, in fact that their structural and machine components are operating beyond their original design lives of 30 to 40 years. Considering the economic difficulties associated with building new plants, there is a growing need to predict life expectancy of steel, particularly those in operating for extended periods at high temperatures. Several techniques can be used to obtain life-prediction information. One of them is surface replication. The area to be replicated is grinded and polished. The surface is then etched to reveal the microstructure. A plastic film is applied, cured and carefully removed. The surface of the film retains a precise, reverse image of the etched component surface. In the laboratory, the replica is examined using light or scanning electron microscopy. There are many advantages of the replication technique. It is totally nondestructive and hence can be used for periodic monitoring. The replicas provide a permanent record of observations and can be stored. An accurate image of the component surface is obtained. It is capable of producing the same high-quality micrograph achieved in conventional metallography. Replication is by far the most sensitive methods of examination as compared with another NDT methods: ultrasonic, X-ray, Dye penetrant, and magneting particle inspection. As replication is the direct method of detecting current creep damage of equipment, it gives valuable information for the remaining life prediction. The stages of damage and degradation of microstructure of pipe-lines were accurately determined from the replicas. Then the remaining life corresponding to various damage stages were calculated for undamaged material, isolated cavitation, oriented cavitation, 1 and microcracking, respectively. For more accurate evaluation of remnant life, other methods are used, which take into account the degree of microdeformation of grain (MDC method), and the number fraction of grain boundaries that are damaged by cavitation or cracking ("A" parameter). Calculations were carried out using a master curve and by the equation: A = 0.517 (t/tr)-0.186 where: A = the number fraction of damaged grain boundaries, t = service life expected. tr = time to rupture. The most accurate methods to evaluate remnant life combine the physical damage and the degradation of the microstructure. P2.15 INFLUENCE OF THE FORM OF STRESS-STRAIN DIAGRAM ON THE SHOCK RESISTANCE OF MATERIAL AND STRUCTURES f L. Slepyan* and M. Ayzenberg-Stepanenko:,** .} *Tel Aviv University. Dept. of Engineering, Tel Aviv. Israel **Negev Advanced Techn. Center. Dimona. Israel The correlation between the material shock resistance an the form of O - £ curve (O is a stress, and e is a strain) is investigated by computer simulation of the structure models consisting of successively linked elements belonging to the same type with fixed tension strength limit Of and corresponding strain limit Ef. Such models are used to describe a plate response to the intense transverse shock. Since a structure resists mainly to tension the membrane approach is quite relevant The one- and two-dimensional strongly nonlinear problems of powerfool transverse shock are analysed. The shock energy is controlled by the value and velocity of an incident rigid mass. The geometry of the o - e curve is selected to reveal the situations when the most of structure material is in a large strain condition. It is found out that the shock resistance depends nonmonotonously on specific failure energy of material. It turns out that decrease of this parameter in the initial part of the diagram results in the rise of structure shock resistance. Conditions for obtaining the most significant increase of shock resistance are established. P2.16 I ENVIRONMENTAL EFFECTS ON THE BEHAVIOR OF CARBON / EPOXY i COMPOSTTE I f Yakob Bainer*, Ariel Grinberg, E.Gutman** i, ff * Israeli Aircraft Industries, RAMTA, Beer Sheva, Israel I **Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel Environmental effects of composite materials interest producers and users when structures are designated to be used in different aggressive environments. Environmental effects on mechanical and physical p properties of carbon/epoxy fabric AW 30/3502 and UD AS4/3502 were tested, while exposing to water, seawater, oil and alkaline solution (TURCO 4215-S at 60°C). The following effects were found: Liquid absorption in fabric is more than in UD. The degree of environmental effect in UD composite, at length direction is more than at the transverse direction. . - Environment effect degree in fabric composite no difference was found between length and transverse directions. Wetting characteristics influence the mechanical properties, such that, when the wetting angle is small the mechanical degradation is large & vice versa. P2.17 ON THE STRUCTURE PERFECTION OF YTTRIUM ALUMINIUM GARNET REAL CRYSTALS Yuri Rosenberg and Isai Feldman School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel Yttrium aluminium garnet (YAG) is one of the most widely used materials in laser technique. In recent years the growth of these crystals doped with rare-earth elements makes a good progress. But still the structure perfection of these crystals grown by different methods (Czochralski, floating zone etc.) is far from desirable. Crystal growth conditions and various defects influence on the homogeneity and optical properties of material obtained. So the characterization of structure defects in YAG crystals is needed and X-ray diffraction is an unsurpassed method for doing that. The facet growth regions are the principal volume defects in YAG crystals grown by floating zone methods. These regions are easily observed on X-ray diffraction topographs obtained by Lang or Berg-Barrett methods. Lattice parameter study on single crystal spectrometer by local precision Bond method shows that there is a systematic difference between lattice parameter in faceted regions and in crystal regions free from facets - that is true for both doped and undoped crystals. The observed difference in lattice parameter corresponds to slightly less oxygen octahedron rotation around < 111 > direction in facet region (3.01 degree) as compared to facet free crystal (3.17 degree). This phenomenon is caused by distinctive atomic site filling sequences as far as lateral growth based on two-dimensional nuc eaucvi nechanism takes place on the facet while adhesive growth is taking place on the off-facei legion. Integrated intensities of 16 selected X-ray Bragg anionic reflections (the structure factors of these reflection do not contain the contribution from cations) were measured on double crystal spectrometer. Using the intensity ratios for reflections with the same interplanar spacing (intensities were corrected for oxygen thermal vibration anisotropy as well) we determined anionic coordinates in YAG crystal. Combining coordinates and measured lattice parameters we got opportunity to fix the concentration of doping elements (Nd, Lu, Cr etc.) to within 0.03 atomic percent. The lattice parameter increase regularities in the boundary between facet and off-facet regions were also investigated. It was shown that rates of increase depend upon crystallographic directions. So cubic symmetry breakdown on the facet region periphery and corresponding birefringence take place. It is possible to describe the crystal lattice at the facet region periphery by means of two lattice parameters: c, parallel to < 112> and a, perpendicular to < 112> direction and c/a = 0.99995 ± 0.00001. P2.18 EFFECT OF SHORT TIME EXPOSURE TO HIGH TEMPERATURE ON THE TENSILE STRENGTH OF AA 2024 - T8 ALUMINIUM SHEETS S. Bar Ziv, A. Cohen, A. Ledelsky RAFAEL - A.D.A., P.O. Box 2250 (27), Haifa 31021, Israel During functional operation, there are several aerospace structural components which are exposed to elevated or high temperature. The duration of exposure is relatively short - up to few tens of seconds. It is resulted in either by propultion motor flame or by aerodynamic heating which is generated due to high velocity flight. The strength properties of structural materials which are heated in this fashion may be heavily degraded. The magnitude of degradation is controlled both by the temperature gained material and the heating duration. No published data were found regarding exposure times shorter then 30 min. In order to establish the strength properties during shorter thermal exposure times (10 to 20 sec), several tests were conducted. AA 2024-T8 sheet tensile specimens, mounted on a servohydraulic testing machine, were rapidly heated by high intensity radiation lamps. Tensile strength values during exposure to various temperature - time profiles, under continous as well as pulse loading conditions, were determined. Room temperature strength after the thermal exposure was also tested. Strenght reduction during short time exposure was found to be substantially smaller comparing with reduction level for 30 min. exposure. Room temperature tensile strength was found to be dramatically influenced by the thermal exposure. Heating the specimens to 300-420°C for only 10 sec. has resulted in yield strength reduction of about 50%. P2.19 r TENSILE PROPERTIES OF NEUTRON IRRADIATED CO WORKED ALUMINUM 6063 ALLOY A. Munitz*, F. Simca*, A. Stechman*, C. Cotler*. M. Talyanker**, and S. Dahan* *Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel **Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel The impact of neutron irradiation of cold-worked Al-6063 on the mechanical properties and the microstructure were investigated, utilizing optical microscopy, scanning electron microscopy, transmission electron microscopy, and tensile measurements. No voids could be observed up to fluences of about 3.3 x 1021 thermal neutrons/cm2 (< 0.625 eV). The uniform elongation as well as the ultimate strength of irradiate Al increase as functions of fluence. Metallographic examination and fractography reveal a decrease in local reduction of final fracture necking. This reduction is accompanied with a morphology transition from ductile transgranular shear rupture, to a combination of transgranular shear rupture with intergranular dimpled rupture. The transgranular shear rupture area increases with fluence. This suggests an increasing brittleness with fluence. P2.22 MICROSTRUCTURE OF TIG AND ELECTRON BEAM COPPER-STAINLESS STEEL WELDS A. Munitz, C. Cotler, H. Sacham, and E, Aberman Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel The microstructures of TIG and electron beam copper/stainless steel weldments were investigated using scanning electron microscopy. The relatively high cooling rates entailing in the welding process results in high bulk supercooling, which in turn, causes two microstructural effects: (i) Melt separation into two liquids: copper rich (LI) and copper poor (L2). Each of the two melts solidified according to a path dictated by the metastable phase boundary. (ii) Enhanced solute trapping of Cu in the oc-Fe phase and Fe in the e-Cu. P2.23 GROWTH OF A METASTABLE EIJTECTIC IN Al-U ALLOYS SOLIDIFIED IN A COPPER MOLD A. Munitz*, M. Talyanker**, C. Cotler*, and E. Nechama* *Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel **Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel High purity aluminum (99.99%) and high purity uranium (99.9%) were used to prepare Al-U alloys with U cc ncentration ranging between 3-22 wt.%. Alloys with the desired composition were melted in a resistance furnace in an alumina crucible under argon atmosphere. After allowing the melt to homogenize for several minutes, it was poured onto a 3/4" diameter copper mold. The microstructure was examined utilizing optical microscopy, scanning electron microscopy, and transmission electron microscopy. Two type of eutectic microstructures were revealed. A metastable eutectic between Al and UAI3, and a stable eutectic between Al and UAI4. The results are discussed in terms of existing solidification theories. y ^ P2.24 SULFUR SEGREGATION ON NICKEL SURFACES O. Segel and M. Polak Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel The segregation of sulfur (bulk concentration < 200 ppm) at nickel surfaces has been studied by Scanning Auger Electron Spectroscopy ;AES) based on the low-energy Ni(MVV) and S(LVV) Auger transitions that are highly surface sensitive. By directing the electron beam on selected grain surfaces, possible anisotropy in the segregation processes could be monitored. The main preliminary findings of the study are: A. Diffusion coefficient and activation energies based on the time and temperature dependencies of sulfur surface coverage. B. Temperature independent (550-750°C) saturation coverage of half a monolayer (6 = 0.5) indicating a stable ordered structure on sulfur of the nickel surfaces. C The Auger fine structure of sulfur [S(LVV)] changes with appearance under certain condition, of calcium and potassium at the surface. Future experiments aimed to elucidate effects of elastic deformation on surface segregation are pianned. P2.25 * POTENTIAL-CURRENT OSCILLATIONS OFTITANIUM ALLOY EXPOSED TO | IN NaBr SOLUTION UNDER APPLIED POTENTIAL CONDITIONS f Y. Shterenberg and D. Itzhak K Department of Materials Engineering, Ben Gurion University of the Negev, Israel £• '• Ti alloys of ASTM grades Ti-1, Ti-2, Ti-5, Ti-6, Ti-7, Ti-11 and Ti-12 were exposed to a solution of IN NaBr under inductive applied DC potential conditions. With Ti-1, Ti-2, Ti-?, Ti-11 and Ti-12 sparse but deep pits we i found. With Ti-5 and Ti-6 large number and shallow pits were found. During the tests, harmonic oscillations of potential and current were recorded. The phenomenon is pronounced in the monophase containing pd alloys, Ti-7 and Ti-11, and can be also observed in Ti-1, Ti-2 and Ti-12. In double phase alloys Ti-5 and Ti-6 the phenomenon is less apparent. Under applied potential of 5 volts the range of potential oscillations was 180 mV in Ti-12, and 120 mV in Ti-1 and Ti-2. In Ti-5 and Ti-6 the range was about 10 mV. The overall phenomenon of oscillations occurs between the breakdown,EB , and the pitting potential, Epp, and is related to the pitting evolving processes. P2.26 MODEL FOR PHASE FORMATION IN THIN-FILM METAL/SEMICONDUCTOR SYSTEMS FROM AN AMORPHOUS INTERLAYER M. Beregovsky and M. Eizenberg Department of Materials Engineering, Technion, Israel Institute of Technology, Haifa 32000, Israel Experimental observations of certain sequences of compound formation in metal/semiconductor systems can not be explained by existing models. In this work we propose a model of phase formation from an amorphous interlayer, which is formed in many systems between the deposited metal (Me) and the semiconductor substrate (X) at the earliest stage of reaction. The process in the Me/X system should proceed in such a way that at any moment the degradation rate of the free energy of the system should be maximal. The formation (or destruction) of a specific phase proceeds in accordance with the following reaction: -Mei x + rMe Mei.Co XCo =* 1 • y y i -c Xc where Mei. Co XQ> is the amorphous phase formed initially between the metal and the substrate, namely, the liquid-like solution of Me and X, Mei. y Xy is the formed crystalline phase, and Mel - C XC is the residua! amorphous phase, which is in equilibrium with the formed crystalline phase. A simple analytical dependence of the free energy degradation rate for crystalline phase formation (destruction) reactions on the composition of the amorphous interlayer and temperature has been constructed. As a result, the sequence of phase formation in thin-film metal/semiconductor systems can be determined. The general behaviour was found to be bound between two limiting cases: reaction and diffusion controlled processes. This model has been applied to the Ti/Sii_x Ge* system. It is shown that the experimental data for Ti/Si and Ti/Ge subsystems are in good agreement with the obtained result for the reaction and the diffusion controlled processes, respectively. Furthemore, our model can explain in general the peculiarities of phase formulation in the complex Ti/Si i. x Ge* system. We thank R. Ghez for useful discussions. P2.27 ANISOTROPY DM RESIDUAL STRAINS AND LATTICE PARAMETER OF REACTIVE SPUTTER-DEPOSITED Zr FILMS ; A. Laor, L. Zevin and J. Pelleg | Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel ^ Lattice parameter anisotropy is a well documented phenomenon in sputter-deposited ZrN films. The lattice parameter calculated from (111) diffraction peaks, is greater than the lattice parameters calculated on the basis of the other peaks. The mechanisms suggested to explain the anisotropy are discussed, and the mostly likely mechanism is indicate. The mechanisms considered are: a) The elastic anisotropy of nitride films, b) The rombohedral distortion, c) Selective entrapment of interstitial atoms, d) Selective growth of lattice defects. The first two mechanisms are rejected as incopatible with the - experimental data. The remaining two are possible but, preference is given to the selective entrapment of interstitials. This approach is taken because it seems to explain the development of microstrains and it is in the line with the X-ray technique applied to evaluate macrostrains. P2.28 I HYDROGEN INTERACTION WTTH NICKEL PRE-IMPLANTED WTTH He: | THE EFFECT OF THE DOSE AND TOOT-IMPLANTATION ANNEALING | E. Abramov*' **, G. Solovioff**, Y. Grinberg*, G.D. Lampert*** and D. Eliezer ** | *Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel **Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel ***Soreq Nuclear Research Center, Yavne, Israel The thermal desorption technique has been used to study the trapping of deuterium atoms in polycrystalline nickel pre-implanted with helium. Helium dose ranged from 1 x 1019 to 4 x 1021 ions/m2. A computer code was used to simulate the deuterium flux curves and the trapping characteristics. The effect of post-implantation annealing at 703-923K on trapping parameters was investigated. The effective binding energy Ebeff, was estimated to be in the range of 0.4-0.52 eV. The effect of helium dose and post-implantation annealing on trapping characteristics can be related to changes in helium clusters or bubbles configuration. The present study can improve the evaluation of hydrogen isotopes balance on future thermonuclear fusion reactors. P2.30 I STRESS CRACKING AS A RESULT OF HYDRIDE FORMATION IN U-0.1% Cr S. Zalkind*. R. Ashcenazy*, S. Harush*, A. Venkert*, D. Moreno*, D. Halperin* and E. Abramov*1 ** *Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel **Department of Materials Engineering, Ben Gurion University, Beer Sheva, Israel The alloy U-0.1%Cr was developed for heavy water nuclear reactors. This alloy and similar can also be used in future hybride (Fission/fusion) reactors blankets. During service, the alloy might be exposed to hostile environments, especially, humidity, for long periods. Corrosion and stress corrosion cracking due to humidity can cause failure and limit the service lifetime. Therefore, it is necessary to investigate this phenomenon. The present study reports the stress corrosion cracking in U-0.1%Cr alloy, caused by hydride formation due to humidity. Rivets were induced and pressed into adapted bores in plates, both made of U-0.1 %Cr. The assembled specimens were placed for several periods of time (up to three years) in different environments containing humidity. After aging a large amount of corrosion products were found at the rivet-bore interface of the specimens. Radial cracks, developed in the bore edge were detected for some specimens. X-ray diffraction patterns of the corrosion products showed mostly UH3 and some UO2. The sample was examined by metallographic techniques using both light and electron microscopy. The hydride phase which was observed, penetrated int o the metal forming a needle-like shape. Cracks were seen propagating into the hydride path. The formation of the hydride phase, which has a much lower density compared to the metal, yieled in a large volume change and therefore causing development of high stresses in the interface. Calculations shows that those stresses are high enough to yield the metal. P2.32 C VD AND MBE OF RAREFIED H2 OF SiGe SOLID SOLUTION Klara Ljutovich Institute of Electronics, Uzbek Academy of Sciences, Tashkent, 700143, Uzbekistan This paper reviews our studies of SiGe such as: chemistry of growth processes, growth kinetics, mechanisms of crystallization, parameters affected by the change in crystallization mechanisms, etc. Particular attention is paid to the layers properties related to the composition, thickness, surface morphology and interface character, dopants behavior, and electrical and optical parameters. As a result of programmed growth conditions the formation of layers with controlled Si and Ge distribution profiles is described. Such layers are shown to have the lowest density of interface defects and the highest mobility of carriers. We have proposed our mode of MBE in the medium of rarefied hydrogen as an alternative method for UHV MBE. To grow SiGe layers on Si, Ge, and sapphire substrates we used HF-heating and autocrucible sources. Device applications in bipolar transistors, photodetectors, solar cells etc. will also be discussed. P2.33 i i THE BEHAVIOUR OF METALS UNDER INDUCED POTENTIAL D. Itzhak* and H. Straze** *Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel **Bromide Compounds Ltd, Beer Sheva, Israel Stainless steels and other passive metals like Ti, Ta and Nb (The Valve metals), are used as construction materials in the Chemical industry. These metals, characterized by an anodic active-passive behaviour, are generally attacked by a local type of corrosion, usually crevice and pitting. These corrosion phenomena are accelerated under the influence of high induced potentials. The sensitivity of AISI 316 stainless steel and the metals Ti, Ta and Nb to induced potential terms, was investigated in electrolyte solutions, containing bromide and chloride ions. The main results of this work are: a: The breakdown potentials and the steady state corrosion potentials of the tested metals are lower in chemical environments containing bromide ions with respect to those containing chloride ions. b: The pitting corrosion phenomena was accelerated in bromide containing solutions, c: Crevice corrosion phenomena was accelerated in chloride containing solutions. d: The oxide layer developed on the metals Ti, Ta and Nb was approximately ten times thicker in solutions containing chloride ions than the layer developed on these me*als solutions containing bromide ions. The main finding arising from this work is the ability of the bromide ion to cause a dielectric breakdown, in lower anodic over voltage, to isolating or semiconducting oxides protecting the metals Ti, Ta and Nb and AISI 316 stainless steel, than chloride ion containing media. 1 P2.36 HYDROGEN INDUCED BLISTERS FORMATION AND GROWTH IN NICKEL PRE-IMPL ANTED WITH HELIUM G. Solovioff*, E. Abramov** and D. Eliezer* *Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel **Nuclear Research Center-Negev, POB 9001, Beer Sheva, Israel The technological interest in helium behaviour in metals stems to a large degree from fusion first wall and fission reactor applications. In fusion reactors helium is formed in the first wall by severe a bombardment and by tritium decay. In such a device, helium is formed moreover, by an (n, a) reactions whose origin is from the high flux of very energetic neutrons (~ 14 MeV). The purpose of this work is to analyse the effect of helium implantation and hydrogen charging on the surface behaviour of polycrystalline nickel (99.9%). Samples were electropolished against a nickel cathode in a 60% H2SO4 aqueous solution at room temperature until a clean and shining surface was obtained. The electropolished samples were irradiated with helium ions in a electromagnetic isotope separator. Acceleration energies of the helium ions ranged from 10 to 40 keV. The samples were cathodically charged at 10 mA/cm2 current density during 24 hr. This hydrogen charging was carried out at room temperature in 5% H2SO4 solution, with 5 mg/l NaAsC>2 added as a H-recombination poison. After and before every step the specimens were examined by SEM observations and X-ray diffraction. Whenever blisters were present after implantation, blister growth and exfoliation were found after the later hydrogen charging. The study indicate that blisters growth can occurs due to the coalescence of helium implantation zones. A schematic description which explains blister formation and growth due to hydrogen charging of pre-implanted metals will be suggested. P2.37 I THE CORROSION BEHAVIOR OF TITANIUM-ALUMINIDE ALLOYS i A. Ben-Gigi, G. Solovioff and D. Eliezer I •' Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel Modern transportation systems require minimum vehicle weight and high efficiency power plants to achieve high performance and low full consumption. These basic criteria apply to air, sea or ground vehicles, and in each case similar material problems limit current design capability. Titanium Aluminides ordered aitoys: they possess high specific strength and stiffness, excellent ueep properties, and good oxidation resistance at elevated temperature. These properties make it potential candidate for modern transportation systems. In view of the fact that these materials are likely to encounter aggressive environments during service, the influence of sulphuric acid and sodium chloride on the corrosion behavior of these materials was investigated. The corrosion behavior was investigated by pelentiodynamic technique, and scanning electron microscope (S.E.M) after and before being exposed to high anodic potential. The comparison between the potentiodynamic curves and the S.E.M observations showed a good correlation. All specimens exhibited active to passive transition in 3% NaCl with pitting formation at the transpassive potential. The range of passivation decreases as the amount of aluminium in the alloy decreases. A very stable passivation behavior was shown in all the specimens in 30% H2SO4 (except for the Ti 25A1 lONb 3V IMo alloy). All the samples show passivation layer breakdown and new layer rebuild. 1 More corrosion aspect will be discussed. P2.38 HYDROGEN EFFECTS IN Al-Al3Ti-SiCp G. Solovioff*. E.J. Lavemia**, E. Abramov* and D. Eliezer* *Ben Gurion University, Department of Materials Engineering, BeerSheva, Israel **University of California, Irvine, CA 92717, U.S.A Al-Ti alloys are being studied as potential candidate matrix materials in metal matrix composites (MMCs) in an effort to further increase the alloys' modulus and strength. In the present study, spray atomized, co-deposited and extruded Al-Al3Ti-SiCp MMCs. Transmission Electron Microscopy (TEM) was carried out on uncharged and charged samples in order to precisely identify the composition of the precipitates and in order to study the hydrogen effects on the morphology. The matrix and the precipitates were identified by a TEM-SAD pattern analysis. The Al matrix is composed by small (0.3-1.5 |ilm) equiaxed grains that surround the elongated A^Ti precipitates. Two classes of particles were found in the specimen: lfjrn wide and 3 to 5 \im length acicular Al3Ti particles and 3 \im irregular SiCp. The SiCp are small in number. There are many more A^Ti particles, but both types are dispersed homogeneously. The results show that under severe conditions such as exposure to NaCl solutions at cathodic charging conditions, initial crack propagation in Al-Ti/SiCp MMCs occurs without any applied stress. In all of the samples investigated hydrogen induced crack and voids at the reinforcement-matrix interface were present on the charged specimens. Therefore it can be concluded that even in absence of hydride formation there is the possibility that local increased concentrations of hydrogen exist and assist crack initiation and growth. It would appear that for the composite, there is always the possibility for preferential hydrogen accumulation at the large number of incoherent interfaces between the reinforcement particles and the matrix. P2.39 THE CORROSION BEHAVIOR OF Al / Al3Ti / SiC N. Wertsman*, G. Solovioff*, E.J. Lavernia** and D. Eliezer* *Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel **University of California, Irvine, CA 92717, U.S.A The development of advanced vehicles require several properties such as high strength to density ratio, high creep resistance and high resistance to corrosive environments. These requirements can be fulfilled by using Aluminium Titanium alloys as Intermetallics in Metal Matrix Composites (MMC). Rapid solidification during the manufacturing process will improve the performance of these materials. This work presents a research about the corrosion behavior of the Al-3 wt %Ti intermetallic compound reinforced by SiC particles. The measurements wee done in two solutions, NaCl 0.5N and H2SO4 3.67N at room temperature. The experimental methods included dipping the samples in the solutions for 24 and 72 hours and then SEM observation (surface and cross-section), WDS analysis and quantitative X-ray analysis were carried out too. Polarization potentiodynamic curves were used to characterise the corrosion parameters of the samples in the solutions. The samples showed very poor resistance to the sulphuric acid environment and severe pitting was observed, while dipping in the sodium chloride solution yielded corrosion products which appeared as spheric salt (AICI3) particles on the surface and caused crevice corrosion but no local pitting was found. The polarization curves showed no passivation domain in both solutions and different Taffel slopes in the cathodic curve. P2.40 HYDROGEN EFFECT ON THE ORDERED ORTHORHOMBIC Ti2NbAl BASED ALLOYS N. Stern, G. Solovioff and D. Eliezer Ben Gurion University, Department of Materials Engineering, Beer Sheva, Israel The need for low density structural materials with high temperature strength and low temperature ductility for aerospace application has driven interest in titanium aluminides, and especially in those of the Ti-Al-Nb system. Studies of the ternary Ti-AI-Nb alloy system have led to discovery of new ternary phases as the ordered orthorhombic O phase. Recently discovered ordered orthorhombic (O) Ti2NbAl-based alloys have demonstrated greater specific strength and greater fracture toughness than current TC3 Al-Nb based alloys. The major concern in the use of this class of materials, however, is the potential for embrittlement from exposure to hydrogen. Because titanium hydrides are known to adversely affect the strength and ductility of titanium based alloys, the formation of hydrides in titanium aluminides from hydrogen absorbed during service at high temperatures upon cooling is of particular concern. Recently, FCC of hydride phase was found in the BCC P - Ti alloy (Ti-30Mo Wt.%). The present study was carried out on sample of Ti-22Al-2Nb at.% alloy supplied by General Electric Alloys Properties Laboratory (USA). The hydrogen charging was performed in a charging cell at room temperature in the absence of any externally applied stresses in a 1 N H2SO4 solution with 0.25gr of NaAsO2 per liter added as a hydrogen recombination poison. A platinum counter electrode and a current density of 0.025-1 A/cm2 were used. The charging times were in the range of 12-120 hours. The as received specimens and the hydrogen charged specimens were characterised by X-ray diffractometry and Scanning Electron Microscopy (SEM). The main results for the as received specimens were: 1. The lattice parameters of the ordered orthorhombic (O) and BCC (po) phases were determined. 2. The microstructure consists of a large amount of O phases (~nm) particles within large grains of Po matrix. The preliminary results on the potential embrittlement of hydrogen on this alloy were: 1. No significant changes in the microstructure were observed. 2. Changes of the X-ray diffraction pattern were observed as a function of the cathodic charging times. Growth in the intensity of particular peeks may suggest a formation of FCC-Ti 8 hydride. F2.41 PHASE FORMATION BETWEEN CO-DEPOSITED Co-Ta THIN FILM AND SINGLE CRYSTAL SILICON SUBSTRATE G. Briskin, J. Pelleg and M. Talyanker Dept. of Materials Engineering, Ben Gurion University , Beer Sheva, Israel Metal silicides have been received much interest in recent years due to their application as contact materials, gate electrodes, or interconnects in microelectronic devices. Binary alloys of near-noble refractory metals have attracted interest for shallow silicide contacts in VLSI circuits. The object of the present work is to investigate formation in co-deposited Co-Ta film, of 1500 A thickness, on silicon n-type substrate of <100> or <111> orientation. X-ray diffraction and transmission electron microscopy were used to study phase transitions in the temperature range of 600-1109'C. It was found that in addition to the silicide phases of Co and Ta, an additional intermetallic compound of Co2Ta was formed. This phase appears only at the lower temperature range of 6OO-8OO°C. At temperatures between 900- 1100°C only the silicon rich phases were present. These are the low resistivity phases useful in the devices. No ternary phases have been observed. It was observed that silicide formation occurs at faster rate on <111> oriented silicon substrate. P2.42 THE SOURCE OF FRINGE CONTRAST OBSERVED IN THE INTERFACE BETWEEN HELIUM BUBBLE AND CuBe ALLOY MATRIX D. Moreno* and D. Eliezer** *NRCN, Beer Sheva, Israel **Dept. of Materials Engineering, Ben Guiion University , Beer Sheva, Israel The implantation of helium in metals causes the formation of helium bubbles and creates an order array called bubble superlattice. This phenomenon has been investigated widely and the most extensive studies of the structural nature of the gas bubbles super-lattice have been for copper [1-3]. At low implantation temperatures, vacancies have only limited mobility. In this case, the bubbles are overpressurrized and grow by an athermal process such as dislocation punching. The lattices of the arranged bubbles and the matrix of the host metal are oriented for diffraction along common planes but there is little understanding of the helium structure inside the bubbles. In theoretical studies, the calculated helium pressure arrives at values that are consistent with solid state helium. As a result of the typical size of these implanted bubbles, there is no technique available to prove this statement. The present work reports on the observed contrast features at interphase interfaces by high resolution transmission electron microscopy. The principal features are interfacial dislocations by means of Aw fringes [4]. Aco fringes generally arise at interfaces having correlated lattices which ar oriented for diffraction by common planes such that the deviation parameter a> is different for each crystal structure. The finite value of Ao) arises from a misfit between the host metal lattice around the bubbles and the helium structure. This misfit increases by the strain field created in the interface as a result of the bubbles growth and displacement of the bubble interface. The observed Aco fringes around the bubbles raise the possibility that the helium atoms are arranged in a specific structure since the Aco fringes are usually obtained by interaction of two lattices at the interface. REFERENCES 1. P.B. Johnson, A.L. Malcolm and D.J. Mazey, Nature 32, (1987), 316. 2. P.B. Johnson, A.L. Malcolm and D.J. Mazey, J. Nucl. Mater. 152, (1988), 69. 3. P.B. Johnson, A.L. Disprose (nee Malcolm) and D.J. Mazey, J. Nucl. Mater. 158, (1988), 108 4. R.C. Pond, J. of Microscopy 135, (1984), 213-240. P2.43 FCGR AND FRACTURE TOUGHNESS IN Ti-6AI-4V OF DIFFERENT MORPHOLOGIES J. Brandelstein* and L. Levin** *Metal Technologies Center, RAFAEL, Haifa, Israel ••Department of Materials Engineering, Technion, Haifa, Israel Modifications to the microstructure of Ti-6A1-4V were obtained, from a series of thermomechanical, thermochemical and two-stage thermal treatments which included temporary alloying with hydrogen. Values of fracture toughness Kjc and rates of fatigue-crack growth (FCGR), da/dN vs AK, were determined for each microstructure. The influence of the phase and morphological structure of the material on each region on the da/dN curve was examined, and a considerable dependence on the morphology was found for the I and HI regions. It was shown that the transition point between the I and II regions can be calculated from morphological data which was obtained by means of an image analyzer. The results indicate optimal values of fracture toughness in microstructure of the Broken- up type. P2.44 THE EFFECT OF MACHINING PARAMETERS ON THE SURFACE ROUGHNESS OF Ni COATED Al MIRRORS G. Kohn*, Y. Shneor** and R. Papiar*** *Dept. of Materials Engineering, Ben-Gurion University, Beer-Sheva, Israel **Rotem Industries Ltd., Rotmax Division, Beer-Sheva, Israel ***Israel Aviation Industries, Yahud, Israel The Rotmax Division of Rotem Industries Ltd., has been engaged for some time, together with the scientists of the NRCN, in the development and manufacture of components which demand ultra-precision engineering. The final machining steps of these components are done by computer-controlled ultra-precision diamond turning lathes (PDT). PDT systems are used in the manufacture process of optical components with stringent requirements on surface quality and dimensions. Flat, spherical and aspherical metal mirrors for laser applications, video tape recorder heads, and memory discs for computers, are a partial list of components manufactured using this method. The metals which are commonly used as substrate materials are among others, aluminium, copper and molybdenum. The surface quality achieved by PDT is a few hundredth of a micrometer with dimensional tolerances of several micrometers. Natural diamond cutting tools, with a very sharp cutting edge, are used in this machining process. Linear cutting speeds range between 100-1000 mm/min and the depth of cut very from 1-50 \xm. Tool motion per revolution is dependent on tool radius and the desired surface quality, and ranges between 0.5 and 10 |im/rev. This paper describes the general features of the ultra-precision diamond turning facility available at Rotmax Division. The production steps of nickel-coated aluminum mirrors are described together with the necessary testing procedures involved in the evaluation of the final surface roughness of the product P2.45 A NEW SELECTIVELY ABSORBING COATING T. Werber and J. Yahalom Department of Materials Engineering, Technion-Israel Institute of Technology, Haifa, 32000, Israel A novel kind of selectively absorbing coating for operations at temperatures higher than 300°C has been elaborated. The selective absorbing surface is an absorbing reflecting tandem NiO/Ni2Al3. The preparation of the selective absorbing surface is based on the formation of a nickel aluminide coating following conversion of its upper layer into an NiO layer by a chemical conversion process. Optical tests (hemispheric reflectance, absorptivity and emissivity measurements) have shown that the coating's selective absorbing properties are very good. In addition, the coating has high stability against environmental deterioration. P2.45 CONTROLLED THERMOPROTECTTVE COATING? FOR GAS TURBINES E. Shvarzshtein, T. Werber, J. Yahalom Department of Materials Engineering, Technion-Israel Institute of Technology, Haifa, 32000, Israel It is imjpossible to prevent ash deposition in the hot gases duct when the concentration of solid impurities in the gas stream exceeds the order of 1 ppm. The proposed approach consists of utilizing oxide-based deposit formations for increasing the surface durability of turbine blades and vanes. A basic factor in the protecting action of this kind of deposit is mass exchange with the working environment. The deposits are converted into a dynamically sustained coating when they survive as entrainment or wear loss. These deposits are built up by the environment throughout the operation period. This kind of a coating is termed a controllable thermoprotective coating (CTC). A CTC acts as a protective layer against material losses caused by wear of hot combustion gas streams, as well as erosion by impact of solid particles in such streams. The CTC also acts as thermoprotective barrier coating (TBC) because the deposit has a low thermal conductivity. The anticorrosion protection of CTC has an indirect character. The oxidation rate of the superalloy support is diminished in consequence of a decrease in the component temperature in TBC action as well as by suppressing the erosion in the synergetic oxidation-erosion process.67 P2.47 THEORETICAL METHOD FOR CALCULATION OFTHE DIFFUSION DEPTH C. Samoila University Transylvania of Brasov The paper presents a theoretical method based on the dimensional analysis through which can be established an analytical correlation of the factors that characterise the phenomena of diffusion at thermochemistry treatment; when the number of these factors surpass the possibilities of Fick's law. The examples will refer to the sulphatization of the small pieces of alloys. P2.48 METHODS FOR OBTAINING METALLIC MAGNESIUM FOR MODIFICATION OF NODULAR CAST IRON A. Crisan and I. Ciobanu University Transylvania of Brasov The paper presents a study about the production of granular metallic magnesium, a study that can be used at modification of S.G. Iron. Through general methods used for obtaining metallic granules, the paper presents two methods - the centrifugal casting and the vibratory stress of liquid alloy. After delivery or some conclusions about theoretical methods there are presented some equipment for laboratory and the experimental results. It makes a comparison between the theoretical and experimental results for the laboratory equipments that are used. The conclusions about the ways for obtaining granular metallic magnesium with good quality for modification of S.G. Iron are presented. P2.49 HYDRIDES FORMATION IN ct2 AND yTITANRJM M. Dangur, J. Haddad and D. Eliezer Dept. of Materials Engineering, Ben Gurion University of the Negev, Beer Sheva, Israel I lydrogen degradation of the mechanical and fracture behavior of titanium alloys can be a complex process, influenced both by hydrogen transport and the form and extent of the hydrogen-material interactions. A preliminary study was conducted on hydrogen embrittlement of titanium alloy. The main results of the present study show that hydrogen induced cracking or hydrides formation in ct2 and y. There is a general agreement as to the segre^'ion of hydrogen from the metal matrix to preferred location. The trapping of hydrogen is caused by the existence of locations which have an energetic locations in the lattice. The theoretical approach to hydrogen brittlements of intermetallic titanium 012, and y is concerned with the development of mechanisms which explain the kinetics of the trapping. The dislocations cause mobility which leads to convergence. At this point, nucleation and growth of new brittle hydride phase take place. P2.50 Ge SIGLE CRYSTAL FILMS GROWN BY MBE ON (Ca, Sr) F2 / AL2O3 AND GaAs SUBSTRATES E. Redmard*, E. Griinbaum* and G. Deutsher** *Faculty of Engineering, Tel Aviv University, Ramat Aviv, Israel **School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Israel Ge single crystal (S.C.) film is an attractive choice both as a bottom cell and as substrate for CaAs and AlGaAs top cell growth in tanden solar cell configurations. High purity S.C. Ge films were grown in UHV system by MBE (Molecular beam epitaxy) on GaAs (100) S.C. wafers and on Cao.4Sro.6F2 S.C. films grown in turn on AI2O3 (1T02) substrates. Large area (2x2 cm2), 3-10 |Am thick, self supporting Ge films were obtained by etching away the (CP, Sr) F2 inter layer thus separating the Ge film from the sapphire substrate. The sapphire substrates were reused after proper cleaning. The films were studied by SEM, RHEED and XRD. P2.51 WIDE ANGLE XRD STUDY OF THE EFFECT OF PROCESSING CONDITIONS ON POLY (P • PHENYLENE 3ENZOBKTHIAZOLE) E.L. Garstein and Y. Cohen Department of Chemical Engineering, Technion, Haifa 32000, Israel Fibers and films exhibiting exceptional mechanical properties have been developed from rigid rod polymers by processing from solution in a way which provides very high alignment of the rigid chains. The success in translating the molecular strength and the stiffness of the individual rigid chains to macroscopic properites relies on suitable morphology on the supramolecular scale, and it is therefore important to characterize the microstructure on this scale. In continuation of our SAXS study1 of polymer wet films as-dried in a supercritical CO2 and also subjected to heat treatment by drawing trough the furnace at 600°C for 10 sec, we have performed meridional scans (in the direction of fiber axis) employing symmetrical transmission technique and equatorial scans (perpendicular to the fiber axis) employing symmetrical reflection technique. The presence of the multiple meridional reflections pointed to a good orentation of the molecules, as well as to the high degree of axial order. From the WAXS photographs recorded using Statton camera, the preferred orientation was found to improve according to the azimuthal angle a = 27° - 30° to a = 22° - 25° for the as-CC>2 dried and the heat treated films, respectively. The equatorial scans showed that the 3-D crystallinity improved with heat treatment, since the overlapping reflections became better resolved. The lateral size of the crystallites estimated from the breadth of the equatorial peaks using the Debye-Scherrer formula increased from 4 nm to 11 nm. The observed sharpening of the meridional reflections with heat treatment also indicated on the possible combination of the reduction of the disorder and/or increase in the crystallite size. It is much of interest now to apply the paracrystallinity models for the detailed interpretation, of the diffraction spectra. 1. Y. Cohen and E. Garstein, Proc. 5th Isr. Mater. Sci. Soc., Haifa (1990), p. 259, eds. M. Bumberger and M. Schorr, Freund Publishing House, Ltd. P2.52 OXIDATION GROWTH EM INTERMETALLIC Ti-25-10-3-1 M. Dangur and D. Eliezer Dept. of Materials Engineering, Ben Gurion University of the Negev, Beer Sheva, Israel Reactive elements that contain intermetallic OC2 + P titanium quickly develop oxide by ionic reaction to receive type of oxides such as: T1O2, AI2O3 and NbO2- The oxidation kinetics and morphological features of the intermetallic Ti-25-10-3-1 were investigated. The comparison with the oxidation kinetics of T13AI + P is given by weight gain-oxidation time curves. In the early stage of oxidation, the curves show a parabolic shape indicating formation of a protective oxide thin scale, probably A2IO3, which avoids formation of another brittle oxides in this stage. After the initial transient period, the curve become linear. This behavior of the curve is due to high diffusivity of titanium in AI2O3 scale, resulting in the formation of T1O2 crystalline phase as an external scale. The nucleation and growth of TiO2 phase in the AI2O3 scale produces many pores in particular at the thin scale AI2O3 from 15 fxm to 150 Jim T1O2 oxidation layer. Sufficient aluminium transport from Ti-25-10-3-1 assists the formation of the AI2O3 scale, but it cannot act as a protective film against oxidation. High aluminium concentration in various type of intermetallic titanium can be protective against oxidation and can be used as a coating material. P2.53 LECO CORPORATION 3000 LAKEVIEW AVENUE ST. 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