Iniiiii DK9800177

* 11 iniiiii DK9800177

Materials Research Department

RIS0 1997 www. risoe.dk Materials Research Department

Annual Report 1997

Published by the Materials Research Department Riso National Laboratory April 1998

Ris0-R-1O13(EN) ABSTRACT

Selected activities of the Materials Research Department at Risa National Laboratory during 1997 are described. The scientific work is presented in four chapters: Materials Science, Materials Chemistry, Materials Engineering and Materials Technology. A survey is given of the Department's participation in international collaboration and of its activities within education and training. Furthermore, the main figures outlining the funding and expenditure of the Department are given. Lists of staff members, visiting scientists, publications and other activities are included.

Ris0-R-1O13(EN)

Published by the Materials Research Department, Risa National Laboratory April 1998

Editors: Bent F. Sarensen Niels Hansen

Editorial Board: Eivind Adolph J0rgen B. Bilde-S0rensen Morten Eldrup Grethe Winther Andy Horsewell Torben Leffers Helmer Nilsson Eva Sarensen

Journalistic consultant: Jargen Hornemann

Photos: Boye Koch Helmer Nilsson

Layout: Finn Hagen Madsen

Repro and printing: Holbask Center-Tryk

Cover composed of scanning electron microscope images of microstructures of materials having been subjected to high temperatures.

Materials Research Department Risa National Laboratory DK-4000 Roskilde DENMARK phone +45 4677 5700 fax +45 4677 5758 e-mail [email protected] Internet address: http://www.risoe.dk/afm/home/html

ISBN 87-550-2336-3 ISSN 0106-2840 ISSN 1397-8071 CONTENTS

INTRODUCTION - Materials Research Department 1997

MATERIALS SCIENCE - theory and characterization

7 Materials models and materials structures 13 Local structures and properties 16 Irradiation damage, defects and fusion materials 19 Techniques

22 MATERIALS CHEMISTRY - combined science and technology

23 Fuel cells 25 High-temperature superconductors 27 Techniques

28 MATERIALS ENGINEERING - modelling and performance

29 Design and mechanical testing 32 Properties of advanced composite materials 34 Techniques

36 MATERIALS TECHNOLOGY - synthesis, processing and product

37 Powder technological materials 39 Manufacturing technologies for advanced composite materials 41 Techniques

42 FINANCES 1997

44 PERSONNEL 1997

46 COMMUNITY ACTIVITIES 46 Postgraduate (PhD) projects 47 Undergraduate projects 47 External lecturers and examiners 47 Staff members on assignments abroad 48 Visiting scientists 49 Road shows 49 Colloquia 49 Distance learning courses 50 Participation in committees 51 Symposia and workshops 52 Teaching of high school students 53 Social activities

54 PUBLISHED WORK

64 ACRONYMS, ABBREVIATIONS, ETC. INTRODUCTION - Materials Research Department 1997

The international evaluation of Ris0 and positive development, however, just man obtained this degree. The staff of of the Department in 1996/97 was very balances increases in salaries and oper- the Department now includes four scien- positive with respect to the quality of ating expenses and thereby precludes tists with this title. our scientific and technological work. any substantial new investments. We As a further recognition of the On this basis, the evaluation panel are, however, glad that joint funding quality of basic research in the Depart- suggested that Ris0 should further from the Danish Technical Research ment, The Engineering Science Centre strengthen its many links to society. It Council and from Ris0's central fund has for Structural Characterization and was emphasized that collaboration with allowed us to enter into a collaborative Modelling, financed jointly by The Dan- universities and industry should be agreement with the European Synchro- ish Technical Research Council and Ris0, increased to make better use of Ris0 tron Radiation Facility (ESRF) in Gre- was extended by a further 5 years until resources. This means that future activi- noble, France. The aim of this collabora- 2002. Also to be mentioned is that ties must demonstrate solid links be- tion is the construction of a high energy electron microscopy has provided impor- tween research and teaching and be- X-ray diffractometer. This instrument, to tant new information on the microstruc- tween basic work and industrial applica- be operative in 1998, will provide break- ture and the chemical composition of tions. Guidelines for these efforts were throughs in materials research by allow- materials ranging from conventional later laid down in the form of specific ing in-depth structural analysis with metals like aluminium, copper and milestones in a 4 year contract between high spatial resolution; a radically new nickel to complex ceramic materials used Ris0 and the Ministry of Research. This technique, dubbed three dimensional X- in high temperature superconductors contract also contained the guarantee ray microscopy. and in solid oxide fuel cells. Measure- that the financial contribution from the ments of internal stresses in polycry- Government to Riso's activities will Achievements stals, thin layered structures and com- remain unchanged until the end of year Many years of research was concluded posites have also progressed well using 2001. Thus, to maintain the current when Dorte Juul Jensen defended her neutron, electron and X-ray diffraction. activity level, external funding (which Dr. technices thesis entitled 'Orientation Other achievements concern the supplements the Government funding) Aspects of Growth During Recrystalli- research and development carried out in must be maintained at least at present zation'. The defence took place at the collaboration with industry. An impor- levels. Fortunately, external funding has Technical University of Denmark and the tant theme has been composite materi- shown a slight increase in 1997, with a event was given more than usual atten- als, especially in the development and further increase expected in 1998. This tion as it was the first time that a wo- optimisation of thermoplastic composites and associated process technologies. There is a strong industrial interest in this type of materials since reduced occupational health hazards can be combined with improved properties of products, for example for windmills and automobiles. This potential has led to the formation of a consortium of 6 Danish industries which, together with the Department and the Danish Techno- logical Institute, has formulated a 4-year research, development and demonstration programme. Also in the composites area, materials with good strength and stiffness have been produced using natural fibres from trees and plants. One aim of this programme is to improve recyclability of products in the automotive and packag- ing industries. Finally, metal matrix composites with extremely high wear resistance have been developed in col- Dorte Juul Jensen (centre) defended her Dr. technices thesis in the laboration with Danish and foreign presence of the the Minister of Research (left) and the director of the Technical University of Denmark (right). industries. Good progress has also been achieved in the energy programmes carried out mainly under the sponsorship of the Danish Ministry of Environment and Energy. The aim here is to improve efficiency and reduce detrimental environmental effects of energy production, transport and usage. These programmes are (i) Solid Oxide Fuel Cells, (ii) High Temperature Superconductors, (iii) Windmill Wings, and (iv) Flywheels. In these programmes, large and medium size Danish firms are the industrial partners. Staff from these companies Video conferencing was used for teaching university st d t _ t participate actively in the work in the way video links (distance learning) and for video conferences. Department with the aim of integrating our joint research and development activities. On the European level, the Depart- ment has participated in a number of programmes within EU's 4th Framework Finally, we held the 18th Interna- programmes that we have completed programme, mainly BRITE-EURAM and tional Ris0 Symposium on Materials over the years may also be seen as JOULE-THERMIE. In 1997, the Depart- Science in September. The title was having provided good training. Such ment has co-ordinated three BRITE- 'Polymeric Composites - Expanding the programmes have shown us the benefit EURAM proposals and participated in Limits'. The 19th symposium, to be held of a good and friendly collaboration two. Three of these five proposals have in September 1998, has the title 'Model- within the whole Department. We are now been approved covering such activi- ling of Structure and Mechanics of therefore confident that we both have ties as forming, non-destructive testing Materials from Microscale to Product'. the competence and the spirit to meet and high temperature materials. Danish the changes occurring around us. industry participates in two of these The coming years To deal with developments taking programmes. These new contracts will With the present portfolio of program- place in society, a broader customer base bring the Department's annual income mes, most of the activities in the coming must be aimed at. Here, it is very posi- from EU's research programmes up to year or two will be along lines known tive that the main requirement in the about 9 mill. Danish kroner (DKK). This today. However, as more than 50 % of new contract between Rise and the is about 25 % of the total external the funding of the Department's activi- Ministry of Research is specifically that funding; this was the target that was set ties comes from external sources, chan- we expand our contact with industry in the beginning of the 4th framework ges around us will have a great impact and universities. Thus, what looks like programme about 4 years ago. on the future directions of our research. an imposed political demand is in fact Also, educational activities may be An example is EU's Framework pro- fully in accord with our visions for the mentioned. Teaching activities range gramme, planned to start in 1999. The future. Many new activities are planned from teaching high school students and programme will, without doubt, be in order to follow the intentions in this high school teachers at Ris0 to external agreed upon and will almost certainly contract. Both for these new activities lecturing of undergraduate and graduate contain an increase in budget compared and for the old ones it is a requirement courses at the Technical University of with the present programme. A change that the research and development must Denmark and Aarhus University. To in priorities can also be predicted, but be both focused and on an international strengthen our contact with Danish the funding of specific areas is at pre- level. It is only by maintaining these universities, the Department has estab- sent unknown. It is therefore mandatory research standards that we can be quali- lished facilities for distance learning and for the Department to be proactive as fied as partners for Danish and interna- video conferencing in a centre initiative before in the formulation of European tional industry, be inspiring teachers at together with 7 universities. Funding and Danish research programmes and the university level and provide solu- was partly provided by the Ministry of this will require great flexibility. In this tions to problems arising in our society Education; the centre was inaugurated situation we are in the fortunate posi- within sectors where materials are devel- by the Minister in May. tion that the many large and complex oped, produced and utilized. MATERIALS SCIENCE - theory and characterization

The research activities to be described within this programme area Project Funded Research: Materials Science cover a very wide range of subjects. The emphasis is on basic and strate- Project type ;. :. Project name Co-participants gic research, but all projects have a Danish Technical Structural • Condensed Matter Physics and Chemistry clear relation to potential technologi- Research Council* Characterization and Department, Rise . Engineering:,; . * Modelling of Materials cal applications. Science Centre (IVC> V'i- • The Engineering Science Centre for Danish Natural. ; ; Danish Centre for • Condensed Matter Physics and Chemistry Structural Characterization and Mod- Science Research \ X-ray Synchrotron Department, Rise Council Radiation • Danish Space Research Institute, Denmark (DANSYNC) • Department of Physics, DTU, Denmark elling of Materials, financed jointly • • '• by the Danish Technical Research H.C. 0rsted Labaratory, NBI, Denmark Haldor Topsee A/S, Denmark Council and Riso, is managed within Department of Chemistry, AU, Denmark the programme area, but the centre Institute of Chemistry, KU, Denmark Royal Danish School of Pharmacy, Denmark also includes many activities from other programme areas (and from the Danish Materials ' Materiats Processing, •" Inst. of Manufacturing Eng., DTU, Denmark Technology : Properties and • Department of Solid Mechanics, DTU, Denmark Condensed Matter Physics and Chem- Programme Modelling Centre • Department of Production, AAU, Denmark : istry Department at Riso). The estab- (MUP) : (MPPM) \ lishment of this centre, in 1993, has Large Installation Neutron Diffraction • Condensed Matter Physics and Chemistry contributed very significantly to the Programme Department, Riso (UP) V , • DR3, Rise programme area and to its interaction with the other programme areas. BRITE-EURAM Improvement of • Hydro Aluminium, a.s., Norway Quality and • Pechiney Recherche, France Productivity for • Granges AB, Sweden Among the highlights one may point Rolled and Extruded • Norwegian University of Science and Aluminium Products Technology, NTNU, Norway to (i) identification of the cross-slip through Microstructure • Ecoles des.Mines de Saint-Etienne, France mechanism in FCC metals by model- and Texture Modelling • Swedish Institute for Metal Research, Sweden (REAP) • Norwegian Inst. of Technology, SINTEF, Norway ling at the atomic scale, (ii) experimental verification of diffusional BRITE-EURAM Residual Stress Standard • Rolls Royce - Gas Turbines, UK using Neutron Diffraction • Sintech Keramik, Germany creep via microstructural observa- (RESTAND) • Schunk Kohlenstofftechnik, Germany tions, (iii) demonstration of a clear • Volkswagen, Germany • British Aerospace - Airbus, UK relation between the microstructure • AEA Technology, Harwell, UK and the crystallographic orientation • Rutherford Appleton Laboratory, UK • Hahn-Meitner Institute, Germany of grains in tensile deformed poly- • Institute Laue Langevin, France crystals, (iv) experimental confirma- • NFL (Studsvik), Sweden • : • • • : • Joint Research Centre Petten, The Netherlands tion of the production bias model for • University of Cambridge, UK defect accumulation during irradia- • Imperial College London, UK • University of Salford, UK tion, (v) final decision by the Euro- pean Synchrotron Radiation Facility EU-Fusion Materials Effects of • EU-sponsor, in collaboration with: Technology Programme Irradiation on - CRRP, Lausanne, Switzerland to establish a dedicated beam line for (EU-FTP) . Deformation Behaviour - Research Centre Julich, Germany 3D X-ray microscopy in collaboration of Iron and Low - AEA Technology, Harwell, UK Long Term Materials Activation Steels with Riso and (vi) improvement of Programme the methods for correction of beam- EU-FTP Effects of Irradiation • EU-sponsor, in collaboration with: skirt effects in X-ray spectrometry in on Physical and : - Oak Ridge National Laboratory, USA poor-vacuum scanning electron mi- Mechanical Properties - London University, UK Underlying . of Metals - Research Centre Julich, Germany croscopes. Technology - Inst. of Physics and Power Engr., Obninsk, Russia - Pacific Northwest National Laboratory, USA EU-FTP Copper and Copper Alloys • EU-sponsor, in collaboration with: Irradiation Testing for - Pacific Northwest National Laboratory, USA International First Wall and Divertor - University of Illinois, USA Thermonuclear - VTT Manufacturing Technology, Finland Experimental Reactor R & D (ITER) Materials models and materials structures

This programme concerns the development of micromechanical models for the mechanical behaviour of single- and multi-phase materials, including the (multi-phase) microstructure. The models are related to micromechanics and the basic physics as reflected in dislocation processes and, in certain contexts, processes at the atomic level.

Cross-slip of dislocations studied by a new atomistic method Among the many different dislocation reactions taking place during plastic deformation of materials, cross-slip is of special interest, because the cross-slip frequency seems to control the evolution of the deformation induced dislocation The new method of simulation, applied to a computer crystal of copper with 3.4 million atoms, identifies the lowest-energy cross-slip path microstructures as well as the growth of through configuration space. The path corresponds to the mechanism short fatigue cracks. Cross-slip is the proposed by Friedel and Escaig. The blue-coloured atoms show a con- mechanism by which a dissociated screw figuration close to constriction. dislocation changes its glide plane. Different models for the cross-slip mechanism have been proposed, but it modelled roughly 3.4 x 106 atoms. demonstrated (in collaboration with has not been possible so far to determine The cross-slip process was found to Universidad Nacional de Rosario, Argen- the exact mechanism by simulation or be initiated by the formation of a con- tina) that an advanced self-consistent experiment. The reason lies in the com- striction of the dislocation in the pri- model for the plastic deformation of plexity of the problem; a proper treat- mary glide plane. The short segment of polycrystals includes a systematic selec- ment of cross slip of a dissociated screw perfect screw dislocation then redisso- tion of the appropriate rotation rule dislocation from the primary glide plane ciates into the cross-slip plane, thereby depending on the shape of the grains. to the cross-slip plane requires atomistic taking the dislocation from the primary Equiaxed grains lead to MA, and flat- three dimensional simulations, which to the cross-slip plane via a transition tened and elongated grains lead to PSA. have only recently become feasible. state with two twisted dislocation con- For low strains (with equiaxed grains) In the present work (in collaboration strictions. This cross-slip mechanism is the model selects MA. Increasing strain with the Institute of Physics, the Techni- the mechanism by Friedel and Escaig. (with increasing flattening and elonga- cal University of Denmark, where a tion of the grains) leads to a continuous model technique has been developed) Grain shape and lattice rotation dur- transition towards PSA. The theoretically the problem of determining the cross-slip ing plastic deformation predicted transition to PSA is based on mechanism was addressed with the In theories for the formation of deforma- the assumption that a flattened and 'nudged elastic band' method. This tion texture one normally focuses on the elongated grain can be considered to be method is an atomistic method particu- slip pattern - with the assumption that a a homogeneously deforming entity, larly well suited to find optimal transi- specific combination of slip systems which is not necessarily correct. This is a tion paths through configuration space leads to a specific texture. However, this question which is rather fundamental for in cases where simpler methods are not assumption is not correct. A given slip the modelling of polycrystal deformation adequate. To find the optimal transition pattern may theoretically lead to quite at higher strains altogether. path, i.e. to determine how the dissoci- different textures depending on the rules ated screw dislocation changes its glide used for the calculation of the lattice The two-dimensional orientation plane, the method needs only the initial rotations producing the texture. distribution of planar microstructural and final state of the dislocation, but, For rolling deformation (or plane- features importantly, does not include any infor- strain deformation) one may use two The orientation distribution of planar mation about the transition path itself. different sets of rules for the lattice microstructural features like dislocation The simulations were carried out on a rotations: 'mathematical analysis' (MA) walls, twin lamellae and plate-shaped parallel computer, and each simulation and 'plane strain analysis' (PSA). It was precipitates is expressed in a two-dimen-

7 sional pole figure (expressing the distri- croscopic clusters has been suggested to hardened crystal undergo localized bution of the normals or the poles of the provide an alternative explanation of plastic shear with formation of dipole planar features). The experimental ob- planar slip. arrays, possibly by a cross-slip mecha- servations are one-dimensional orienta- The roles of SFE and SRO were both nism. The local dislocation hardening by tion distributions of the traces of the considered in the interpretation of a the dipole arrays shifts the localized planar features on different planar transmission electron microscope (TEM) shear to less soft regions, thus causing sections as observed by microscopical study of the recently observed stages of overall primary hardening. Softening is techniques (optical microscopy or elec- primary hardening, softening and sec- initiated at a stress amplitude sufficient tron microscopy). ondary hardening during cyclic plastic- to trigger formation of ISBs, which The synthesis of the two-dimen- ity of polycrystalline Cu-30%Zn. It was destroy the dipole arrays or the harden- sional orientation distribution from the found that specimens strained into the ing by SRO. Some planar slip materials, one-dimensional trace distributions primary hardening stage contained such as nitrogen alloyed austenitic corresponds to the fundamental proce- arrays of dislocation dipoles in compara- steels, display very short primary hard- dure in the analysis of crystallographic tively undislocated crystal. The onset of ening stages, suggesting that their texture, viz. the synthesis of the three- softening was accompanied by formation cyclic softening is due mainly to de- dimensional orientation distribution of intense shear bands (ISBs) forming struction of SRO. function (ODF) from the two-dimen- preferentially at grain boundaries and sional pole figures. And the basic prob- destroying the initial dipole arrays. In Modelling scale-dependent work lem is the same: the experimental infor- the stage of secondary cyclic hardening hardening in copper-tungsten com- mation is insufficient for a unique the polycrystal was found to contain a posites solution. fairly uniform structure of planar dislo- The prediction and optimization of It has been shown that there is an cation arrays. metal matrix composite behaviour ne- analytical solution for the synthesis of These observations appear to be cessitates an understanding of the the two-dimensional orientation distri- explained equally well in terms of SFE influence exerted by the reinforcement bution of planar features from observa- and SRO: During primary hardening on plastic deformation of the matrix. tion of the trace distributions in two statistically 'softer' regions of the solute Tensile experiments show that this planar sections. Depending on various conditions this analytical solution may or may not come close to the 'proper' solution. On the basis of the present work, new and more sophisticated procedures TEM micrograph of polycrystalline Cu-30%Zn cyclically strained are suggested. The applicability of these into the primary hardening stage procedures remains to be tested in sub- at a plastic strain amplitude of ep sequent theoretical and experimental = 0.0034 (the arrow indicates the primary slip direction). A work. regular array of dislocation dipoles is em-bedded in compara- tively undislocated crystal. Dislocation processes in cyclic plasticity of copper-zinc polycrystals Cyclic plastic deformation of pure metals involves frequent cross-slip events (wavy slip). When alloying elements are added there is usually a transition to planar slip, which apparently involves a lower cross-slip frequency. This type of behaviour is observed when zinc is added to copper. The usual explanation is that reduced stacking fault energy (SFE) causes reduced cross-slip frequency. However/experiments show that planar slip cannot always be correlated with a low SFE. Therefore, short range ordering (SRO) of the alloying atoms into submi-

8 influence can be substantial in the model system of copper reinforced with

a volume fraction Vf of thin parallel tungsten fibres. Thus the in-situ matrix hardening rate is found to be approximately equal to the matrix elastic shear

modulus times Vf/(1-Vf). A new model for this striking effect was proposed (in collaboration with MIT, USA) on the basis of two observations. The first observation is that during fabrication of the composites by liquid infiltration the fibres tend to cluster into close packed bundles. The second observation is that there is a critical value of Vf of approximately 0.5, above which the matrix i? remains non-yielding during a tensile Scanning electron micrograph of a sample of Cu-2wt%Ni deformed experiment. A comparison between 2.4 % in the diffusional creep regime. The sample is covered with a grid predictions from this new fibre cluster of alumina so that the deformation at the individual boundaries can be model and predictions from an earlier measured from the displacement of the grid. The arrow indicates the tensile direction. elastic friction model shows that both models provide quite acceptable agreement with the available experimental observations. The two models are comparable in their basic hardening mecha- tain conditions deform by diffusion of vacancies can be absorbed or emitted nism, since both invoke dislocation material from grain boundaries in com- only at grain boundary dislocations. A mechanisms for the occurrence of non- pression to grain boundaries in tension. number of the predictions derived from yielding regions of matrix. The models This deformation mode is called diffusio- this model have been corroborated by therefore both capture the dependence nal creep. the experiment, e.g. (i) deposition (or of the in-situ matrix hardening rate on In order to achieve a better under- removal) of material at grain boundaries Vf, but they differ somewhat in regard to standing of the processes occurring is coupled to grain boundary sliding and the observed dependence of work hard- at the individual boundaries, a tensile migration (the coupling depends on the ening on fibre diameter. In the elastic specimen of Cu with 2 wt % Ni was grain boundary structure, and therefore friction model the dependence is ex- deformed in the diffusional creep re- the climb/glide ratio varies from bound- plained entirely as a scale-dependent gime. A periodic fiducial grid of alumina ary to boundary), (ii) negative sliding stress relaxation rate, which subtracts was deposited on the specimen prior to may occur at some transverse bounda- from the matrix hardening rate. In the creep. After creep the magnitude of ries, (iii) deposition of material may clustering model a possible source of deposition (or removal) of material and occur at some longitudinal boundaries, scale-dependence can be found in the the magnitude of grain boundary sliding and (iv) boundaries close to an exact expected increase in punched disloca- could then be measured at individual coincident site lattice misorientation are tion density with decreasing fibre diam- boundaries from the displacements of inactive during the deformation. eter and in the dependence on the the grid combined with a knowledge of extent of clustering. Thus, the clustering the orientation of the grain boundary model adds the new possibility that the Evaluation of polycrystalline model- plane. The misorientation across the scale-dependence of work hardening ling scheme by neutron diffraction grain boundaries was determined from arises from a scale-dependent produc- Modelling the mechanics of polycrystal electron back scattering patterns. tion and storage of dislocations inside deformation has been a central issue in the fibre clusters during processing of The experiment unambiguously materials science since the early at- the composite. demonstrated that material was depos- tempts by Taylor and Sachs 60 - 70 years ited on boundaries in tension during ago. The state of the art in terms of creep and that material was removed theoretical analytical modelling schemes Influence of grain boundary structure from some of the longitudinal bounda- is the so-called 'self-consistent' ap- on diffusional creep ries. In a model which we have previ- proach. Such a modelling scheme has A fine-grained material may under cer- ously developed it is assumed that now been fully implemented and with

9 the aim to perfect this approach it is on direct experimental observations. ergy X-ray diffraction is a very powerful now undergoing experimental evaluation An example is the evolution of tool for studying local aspects of defor- by neutron diffraction. Whereas earlier lattice strains in selected families of mation in polycrystalline samples. Thus, work on evaluating such modelling grains in a uniaxially loaded stainless as a complimentary technique to neu- schemes has focused on evaluation of steel specimen. Plasticity was found to tron diffraction it is becoming a valuable the models ability to predict texture develop much earlier on a grain size and necessary tool for the evaluation of evolution, the current evaluation of the scale than as defined macroscopically for the detailed micro-mechanics encoun- evolution of lattice strains and stresses engineering purposes. This early onset tered by the next generation of models is more specifically addressing the me- of plasticity can furthermore be quanti- for polycrystal deformation. chanics of deformation at a grain size fied by focusing on the crystallographic scale. By performing in-situ loading slip pattern predicted by the model. Thermomechanical response of shape experiments on the neutron diffraction Plasticity initiates in grains with a active composites spectrometer, we can selectively choose <531> or a <331> orientation along the Smart materials or structures have been to monitor the lattice strain evolution in macroscopic deformation axis. With a challenge to materials scientists for specific families of grains all being increasing stress, plasticity subsequently many years. One of the most attractive characterized by having a specific spreads to those grains with a <100> metallic candidates for such materials crystallographic orientation along a orientation along the deformation axis. systems is the shape memory alloys of specific direction in the sample. Such which most work has focussed on the experimental observations of lattice Local deformation monitored by nickel titanium system (NiTi). The at- strain evolution are well matched to the synchrotron radiation tractive characteristics of these alloys level of detail in the modelling scheme. The next generation of finite element are the stress and temperature driven We have, as such, a unique opportunity methods (FEM) for polycrystal deforma- crystallographic transformations these to evaluate the model predictions based tion operates at a higher level of detail alloys can undergo. This phase transfor- encountering specific grain-to-grain mation is accompanied by unusual interactions. This calls for novel experi- changes in mechanical properties and mental techniques providing a bulk crystallographic identity, and holds spatial resolution comparable with the opportunities for tailor-making struc- grain size; typically an order of magni- tures with properties which would be tude better than achievable by neutron impossible to obtain in traditional alloy diffraction. During 1997 the Department systems. These special properties of has been engaged in pioneering X-ray shape memory alloys also make them 300 - - diffraction experiments at the European attractive candidates for reinforcements Synchrotron Radiation Facility (ESRF) in in composite systems, and for two years to Grenoble to demonstrate the potential the Department has been engaged in the for investigating single grains in bulk challenge to produce metal based com- material. posites with shape memory alloy fibre

CO reinforcements. •D Pre-strained stainless steel samples CD —in were investigated using an incident The phase transformation character- • 200 100 - 200 - beam cross section of merely 0.4 x 0.4 istics of the shape memory alloys are A 220 mm2 and a photon energy of 68 keV. well documented, and found to be ex- 220 • ft' This allowed full penetration of the 0 tremely sensitive to the thermomecha- 4.5 mm steel specimens while monitor- nical treatment of the materials. It is

500 1000 1500 2000 2500 ing diffraction peaks for single grains hence a challenge to manufacture com- Elastic lattice strain [10"6] along the beam path through the speci- posites through a thermomechanical men. For each local volume combined to/ processing route while retaining the 20-scans were performed to assure full phase transformation characteristics of Comparison of lattice strain evolution in selected grain orientations in a uniaxially 2D-mapping of the diffraction peaks. For embedded fibres of shape memory alloys. loaded stainless steel specimen. Symbols specimens with different plastic strain a As an illustration such a system has indicate experimental observations by dramatic broadening of the diffraction neutron diffraction, while the lines show been brought to a state where it shows model predictions based on a self-consist- peaks was found in the co-direction as a thermal contraction during heating in ent modelling scheme. The non-linearities function of the plastic deformation contrast to the regular thermal expan- develop before reaching the stress level history. sion of metals. The achieved 2.2 % which, in an engineering sense, would be defined as the elastic limit (275 MPa). It was demonstrated that high en- thermal contraction is quite astonishing and points towards the prospects of

10 1.0 homogeneous 0.5: 6082-T6

0.0 d

-0.5- addition, we also discovered that a NiTi-Al changeover between epitaxial and non- in composites epitaxial layer deposition occurs at a -1.0: wavelength of 0.4 microns; this changeover may be attributed to changes in -1.5 current density. Hardness measurements suggested that the strength of the multilayers was -2.0 ~j in accordance with the observed grain (most recent result) size of nickel (Hall-Petch relationship) -2.5 within each structure. Rather controver- 20 40 60 80 100 120 140 sially therefore, we have concluded that the multilayers show no enhanced Temperature (°C) strength due to the layered morphology per se. Previous assertions were that a Thermal contraction of aluminium based composites with fibres of a copper-nickel multilayer with a wave- shape memory alloy. During heating the fibres undergo reverse transfor- length of less than 0.4 microns is harder mation from martensite to austenite resulting in a thermal contraction of the composite, in contrast to the usual thermal expansion of metals, than fine-grained continuous nickel as shown for the unreinforced control specimen. plating. The hardening is now realized to be due to the change to columnar growth in thick nickel coatings. In other words, small wavelength Cu-Ni multilayers are hard because interlayers of developing structures e.g. with zero ray diffraction, cross-section TEM, hard- copper interrupt the changeover to thermal expansion or tailor-made ther- ness testing and tensile testing. columnar growth of nickel and allow the mal expansion (or contraction). The It was found that the copper and nickel deposit to remain extremely fine measurements were done in-situ on the nickel layers were strongly textured. grained and equiaxed. neutron diffraction spectrometer while Grains of copper traversed the layer continuously monitoring the ongoing thicknesses. The nickel layers were fine interior phase transformation of the grained. This is broadly in agreement embedded fibres. The spectacular macro- with that.reported in the literature. In scopic thermal contraction has hence been seen to be directly associated with the reverse transformation of the NiTi- fibres from martensite to austenite.

Microstructure and mechanical properties of copper-nickel multilayers The mechanical strength of both single- and dual-bath electrodeposited Cu-Ni multilayers are known to vary with deposition wavelength. Since we know that layered coatings are harder and more resistant to wear and abrasion than non-layered coatings, this technique is of industrial interest. Optimiza- tion of the process requires a better understanding of the strengthening t Growth mechanisms and the microstructural changes which affect such mechanisms. Cross-section transmission electron micrograph of an electrodeposited copper-nickel multilayer. The copper and nickel layers are strongly To this end we have characterized a textured, with grains of copper traversing the layer thicknesses, while series of Cu-Ni multilayers, covering a the nickel layers are fine grained. In thick coatings of nickel there are wide range of thicknesses of the indi- much larger, columnar grains. Layering of the microstructure on a fine scale thereby allows us to keep the nickel extremely fine grained with a vidual layers in the multilayer, using X- resulting high hardness.

11 tium-chromite were studied. The porous layers were created by air-brushing a suspension of the powder in liquid onto one of the beams before sintering. A cross-section of the sandwich specimen was polished. Crack growth experiments were conducted inside the environmental scanning electron microscope (ESEM), Scanning electron micrograph of a macro inden- using a special fixture that applies pure tation experiment. The spherical indenter was bending moments to the double canti- driven relatively deep into the ductile substrate lever beam specimen. It was difficult to through the brittle titanium nitride coating (PE CVD). The predominant driving force for coating initiate a sharp crack without overload- failure is plastic deformation of the substrate. ing the specimen. But, in specimens The aim of this work is to relate both micro- where crack initiation was successfully scopic observations and depth sensing data to fracture mechanical analysis. obtained, the subsequent crack growth Interfadal crack growth in layered could easily be controlled. The cracks porous ceramic materials grew nearly always along an interface. Thin layers of porous ceramic materials In-situ observations revealed that the are used in solid oxide fuel cells. In presence of pores, however, did affect order to design components against the crack propagation. Sometimes the Residual stress in TiN coatings for delamination it is necessary to measure crack would jump from one interface to wear resistance the fracture energy of the relevant the other. In other cases a new crack initiated ahead of the main crack. The The main objective of this work is to interfaces. Sandwich specimens consist- fracture energy was measured to be 1.5 - study the residual macroscopic stress in ing of a thin porous layer of lanthanum- 2.4 J/m2, which is only about one tenth titanium nitride, TiN, coatings deposited strontium-manganite in between two of the fracture energy of glass. onto a tool steel substrate. The measure- beams of fully dense lanthanum-stron- ments were performed with a 6-9 de- coupled X-ray diffractometer. The coatings were manufactured using an industrial pulsed-DC plasma-enhanced chemical vapour deposition (PE-CVD) technique. The coatings were characterized in terms of microstructure, mechanical and tribological properties. A parametric study of the deposition parameters was performed. Process pressure, bias voltage, temperature and partial gas flow (argon, hydrogen, nitrogen and titanium tetrachloride) were varied in an effort to obtain optimal coating properties. Besides the biaxial stress, the stress free lattice constant,

d0, was determined. Also, we obtained an indication of the changes in texture as a function of process parameters. Total macroscopic stress values were found to range from -1.5 to 1.5 GPa. The intrinsic stresses for the major part of the coatings were close to zero leading The interfacial crack growth in porous ceramic materials is clearly to low intrinsic strain energies. This influenced by the presence of pores. The crack, growing from left to favours a preferred orientation of the right, reaches a large pore, leaves the lower interface and grows along coating corresponding to the plane with the upper interface for a while. As the crack tip extends further to the right, the crack opening increases, the two crack faces come into con- the lowest surface energy which is (100). tact and two parts break off.

12 Local structure and properties

This programme concerns quantitative ous although they are roughly along the Microstructure and grain orientation characterization of microstructures and elongation direction. Between the mac- relations in tensile deformed alu- local crystallographic orientations with roscopic bands there are narrow transiti- minium the aim of understanding mechanical on regions with a width of about 20 |xm High purity polycrystalline aluminium properties and recrystallization. This after a strain of 1.0, which accommodate (99.996 %) was deformed in tension at includes development and automation of continuous orientation gradients. The room temperature. The evolution of the advanced experimental techniques. difference of the macroscopic subdivi- deformation microstructure was charac- sion between rolling and channel die terized by a microstructural analysis of Macroscopic and microscopic subdivi- compression is considered to be due to individual grains by TEM. It was observed sion of cube oriented aluminium the high sensitivity of the cube orienta- that the deformation microstructure was single crystals during rolling and tion to small variations in the macro- never uniform in the whole sample but channel die compression scopic stress state during the channel varied from grain to grain. This observa- Grain orientation is known to have a die compression. tion suggests that grain to grain varia- strong influence on deformation behav- In addition to the macroscopic tions in the slip pattern determine the iour of metals, especially on dislocation subdivision, for both deformation mo- observed microstructures in the grains. structure evolution, work hardening des, a microscopic subdivision by the Under a certain deformation condition, rates, stored energy and subsequent formation of cell-blocks within the the slip pattern in a grain is considered recrystallization mechanisms. The be- matrix bands and an equiaxed cell to be mainly determined by the orienta- haviour of the cube orientation in roll- structure within transition bands (re- tion of that grain. For tensile deforma- ing or plane strain compression is of gions) has been observed. The differ- tion, this grain orientation was charac- major interest because of its industrial ences of the dislocation structure in terized by only a single reference direc- importance for texture control in rolled different regions also resulted in differ- tion, the crystallographic direction being and recrystallized FCC metals. Both ent dislocation density and stored en- parallel to the tensile axis of the sample. rolled and channel die compressed ergy. These were analyzed by consider- In this study, the tensile axis orientation aluminium single crystals of cube orien- ing the active slip systems in different of individual grains was determined in tation were chosen for a systematic regions and the interactions among the the TEM and then related to the observed study of their macroscopic and micro- dislocations. microstructure. scopic subdivision. For both deformation modes, the crystals are split into deformation bands which show rotations mainly around the transverse direction (TD). But the orientation and the size of the deformation bands are very different for the two deformation conditions. During rolling, the crystal is symmetrically subdivided into four matrix bands which are parallel to the rolling plane. Between the four matrix bands there are three transition bands with a width of about 100 |a,m after 50 % rolling, in which the orientation changes continuously from that of one matrix band to that of the adjoining one. A model based on the idea of location-dependent shear strain caused by rolling geometry and friction effects together with plasticity analysis has been proposed to explain the macroscopic subdivision of the crystal. During the channel die compression, SEM micrograph taken using channelling contrast of the ND/RD plane of the size and the orientation of the a 50 % cold-rolled cube oriented single crystal. The changes of the sign of the angle between the long lines and RD along ND define four matrix macroscopic bands are very heterogene- bands, marked Ml, M2, M3 and M4, which are parallel with RD. Be- tween the four matrix bands are the three transition bands.

13 Ill]

preceeding subsection. The dislocation density was calculated at each strain. The shear stress-strain relationship was derived for each of the three groups of grains showing different deformation microstructures, by assuming that the shear stress is proportional to the square root of the dislocation density. The stress-strain curves show a strain hardening behaviour which depends on the orientation of the grain. The behaviour of the grains embedded in the polycrystal was compared with the behaviour of single crystals. The stress-strain curve of the polycrystal was estimated with good accuracy from single crystal data, which were weighted based on a quantitative texture analysis of the polycrystal.

Scaling in polycrystals [100] [110] During plastic deformation, dislocation Relationship between the microstructure type and the tensile axis orientation of grains embedded in polycrystalline aluminium for speci- structures are developed. They can be mens strained in the range 0.05 to 0.34. Type 1: Grains with dislocation characterized by several representative boundaries on the slip plane. Type 2: Grains containing equiaxed cells. lengths: the overall average distance Type 3: Grains with dislocation boundaries not on the slip plane. between dislocations related to the dislocation density, the distance be- In total 90 grains were examined in dimensional cell structure or a cell block tween dislocation boundaries and, fi- four samples of different strains, which structure depends on the multiplicity of nally, the distance between dislocations have orientations distributed over most slip. Fewer dominant active slip systems in a boundary connected with the diso- of the inverse pole figure with <100>, favour the development of the cell block rientation angle between the adjacent <110> and <111> poles at the corners of structure with dislocation boundaries on regions. All these characteristic sizes the standard triangle. According to the the slip planes. With increasing multi- shrink with proceeding deformation, but microstructural characteristics, the plicity of slip, the deviations of the empirically a strong proportionality grains can be grouped into three types dislocation boundaries from the slip between the first two and the inverse showing different microstructures. In planes increase and finally form ran- flow stress is well established. Conse- grains having the <100> direction within domly oriented dislocation boundaries. quently, both lengths are also intimately 15 ° from the tensile direction, randomly related, reflecting some similitude inher- oriented dislocation boundaries are Flow stress, single ent in the structures. If properly deformed, which define a three-dimen- crystals/polycrystals fined, the proportionality coefficients in sional cell structure. In grains next to Pure polycrystalline aluminium (99.996 these scaling laws even become inde- the <100> group, a cell block structure %) having an average grain size of 300 pendent of the material or the deforma- is developed, which is delineated by (j,m was strained in tension at room tion mode. long and straight dislocation boundaries temperature. The flow stress was deter- Recently, after a distinction between that are on or within 5° of parallel to mined at four different strains (0.05, several types of boundaries, an addi- the {111} slip planes. Close to the 0.14, 0.22 and 0.34). Deformation tional scaling law was discovered for <111>, the cell block boundaries become microstructures were characterized cold-rolled aluminium polycrystals. For less straight and deviate from the slip qualitatively and quantitatively by TEM. each individual boundary type, the planes by increasing angles. The grains A classification of the deformation average disorientation angle is inversely with deviation angles larger than 5° microstructures into three different proportional to the boundary distance, constitute the third group. Slip pattern types has shown a correlation between but with different coefficients for differ- analysis in terms of a Schmid factor the grain orientation and the type of ent types. Future investigations have to calculation or a Taylor model indicates deformation microstructure which devel- test if the proportionality factors are that the formation of either a three- ops during straining, as described in the universal or depend on, for example the

14 orientation, the deformation conditions or the material. Furthermore, another type of scaling was found for the distribution functions of the disorientation angles of each kind of boundaries. The measured distributions for several plastic strains collapse into a single master curve after normali- zation by their respective mean disori- •^ • entation angle. According to a recent proposal the existence of more than one set of dislocations in each boundary can explain the observed scaling behaviour. The (modified) Rayleigh-distributions resulting from the model are in good agreement with the experimental data \ 1 /S^-A-T on aluminium. Distributions of similar shape are also found after hot-rolling of steels and hot-compression of copper single crystals. Here, the universal behaviour of the distribution functions \ is caused directly by the geometrical arrangement of the dislocations in the boundary. Establishing such scaling laws is an important guide to distinguish between (a) TEM dark field micrograph of a Al-2%SiC composite strained to 0.1. properties which are material dependent (b) Schematic of the area in (a) showing the principal dislocation or specific for the deformation mode and features. The misorientations of the matrix are indicated by 'vector markers', with length proportional to the rotation angle and direction classes of universal behaviour. Simple related to the rotation direction. structural arguments as similitude or geometrical requirements are sufficient to explain the universality of some flow patterns in the matrix. In the local aligned cylinder-shaped particles the properties, whereas other features like strain map, the strain gradients existing strain in the matrix tends to be largest work-hardening require a more detailed in the matrix following tensile deforma- at the end of the particle and the plastic understanding of the underlying proc- tion was determined. The experimentally flow bands oriented at 45 ° to the tensile esses. derived strain gradients were lower by a axis are often interrupted. For the ~ 45 ° factor of 5 -10 than values estimated by rotated equiaxed particle the develop- Characterization of local strain fields FEM. The conclusion is that high disloca- ment of such bands is favoured. These in metal matrix composites tion mobility results in (i) dislocation observations agree qualitatively well From TEM micro-diffraction studies of structures with more relaxation, and (ii) with the constraint effects of particle local orientations in an aluminium strain fields which are more uniform shape predicted by FEM. composite containing 2 % SiC whiskers than those predicted by FEM. deformed by tension, it was possible to By using the object grating tech- Modelling of anisotropy determine the local misorientation map nique (in collaboration with Dortmund The mechanical anisotropy of metals is and local strain map around individual University), the local strain fields critical for the formability. For example, whiskers. A novel approach to represent- around large particles (> 10 \x,m) in an cups drawn from mechanically aniso- ing misorientations was applied using a aluminium composite containing 10 % tropic materials form ears and develop 'vector marker', i.e. the misorientation Al203 were characterized on a surface of an inhomogenous thickness. Under- vectors show orientation changes not a bulk specimen in a scanning electron standing the origin of anisotropy is only in magnitude but also in direction. microscope (SEM) in-situ during tensile therefore important in order to select This technique allows more information deformation. Effects of particle shape on suitable production methods. It is well to be presented in a way that provides the constrained plastic flow in the asso- known that the texture of a material an intuitively satisfying indication of ciated matrix were observed. For the causes mechanical anisotropy but the

15 Irradiation damage, defects and fusion materials

observed flow stress anisotropy of a Grain boundary mobility during This programme concerns the experi- rolled metal sheet cannot be fully ex- recrystallization of copper mental determination and theoretical plained by texture. Other causes must The migration of grain boundaries is a evaluation of the parameters which therefore exist. The deformation induced vital feature of the industrially impor- characterize the accumulation of defects dislocation walls in rolled materials tant annealing processes of recrystalli- and their effect on the physical and typically have a preferred orientation zation and grain growth. The velocity of mechanical properties of the materials with respect to the rolling coordinate grain boundary migration depends on to be used in fusion reactors, such as system. The dislocation structure is the driving force acting on the boundary ITER (International Thermonuclear hence anisotropic and may therefore and on the mobility of the boundary Experimental Reactor). also lead to mechanical anisotropy. The into the surrounding material. For recry- dislocation walls are expected to resist stallization, there is a paucity of work Kinetic Monte Carlo simulation of deformation by slip in a way similar to on the velocity versus driving force and damage accumulation grain boundaries. Their contribution to mobility relationship. Knowledge about In recent years a considerable amount of the flow stress was modelled by a Hall- this relationship is required as input for effort has been made to understand Petch law where the grain size was physically based modelling of recrystalli- various aspects of production of defects replaced by the distance between the zation kinetics. and their clusters in multi-displacement dislocation walls. This distance is differ- In an investigation of the recrystalli- cascades using molecular dynamics (MD) ent for the different slip systems be- zation of copper, cold rolled 92 %, the simulations. These studies have provided cause it depends on the relative orienta- driving force and the grain boundary some very valuable information regard- tion of the slip system and the disloca- velocity was determined by performing ing intracascade events and the surviv- tion walls. both calorimetric measurements and ing defects, their clusters and morphol- The texture contributions are usually stereological metallographic measure- ogy at the end of the cooling down calculated by the Taylor or Sachs models. ments in the same samples annealed for phase of isolated individual cascades. The contributions from the dislocation selected times at 121 °C. It was found However, global accumulation of defects walls were incorporated in these models that there was a linear dependence of on a macroscopic scale (where inter- through an anisotropic critical shear the average grain boundary velocity on cascade defect interactions and temporal stress given by a Hall-Petch law for each the driving force. The mobility of the and spatial fluctuations in defect size slip system. migrating grain boundaries was deter- and concentration have to be taken into 10 Depending on model parameters the mined to be 6.3 x 10 rnVW. This account) cannot be described at present flow stress in different directions of a mobility value is close to that of grain by MD simulations. Instead, the stochas- rolled sheet was predicted to vary with boundary self-diffusivity in pure copper. tic annealing simulation technique up to 18 % for a random texture. The (which has been developed for describ- model predictions agree well with ex- ing the short-term annealing stages of perimental flow stress data. defect evolution within an individual or a group of cascades) can be used. With this technique, the effects of cascade production on defect accumulation at macroscopic scales can be studied as a function of irradiation time. This type of simulation technique is commonly known as kinetic Monte Carlo. This technique was used (in collaboration with Pacific Northwest National Laboratory, USA) to simulate the evolution of defects produced in copper during continuous irradiation with 14 MeV neutrons at 300 K. The irradiation was simulated by successive introduction of collections of defects and defect clusters representing the primary damage state of individual cascades (as determined by MD simulation) placed in the annealing volume randomly in time

16 and space. Cascade energies and the rate major predictions of the PBM is that the of cascade generation were chosen to defect accumulation above stage V approximate the damage due to the should be recoil energy dependent. In neutron flux of the 14 MeV neutron the present work (in collaboration with source RTNS-II (Rotating Target Neutron IPPE, Russia), the effect of recoil energy Source). The cascades were chosen from on defect accumulation under 2.5 MeV a library of cascades generated in MD electron, 3 MeV proton and fission simulations for recoil energies in the neutron irradiation has been investi- range 5-25 keV. The numbers of each gated. Calculations were carried out in type of defect, defect cluster size distri- terms of PBM using one-dimensional butions, as well as the positions of glide of SIA clusters, sessile-glissile loop defects within the crystal were moni- transformation and size distribution tored as a function of irradiation time function. The calculated components of (displacement dose). The highest dose of the irradiation-induced microstructure slightly more than 0.1 dpa (displace- (i.e. size and density of SFT (stacking ments per atom) was obtained by intro- fault tetrahedra), SIA clusters and voids) ducing approximately 12,000 cascades and their dose dependence for copper into the annealing volume. The calcu- irradiated with 3 MeV protons and fis- lated dose dependence of cluster density sion neutrons were found to be in very was found to be in good agreement with good agreement with the experimental the experimental results. results. The void swelling behaviour observed under 2.5 MeV electron irradia- Effects of recoil energy on damage tion where defects are produced in the accumulation calculated using the form of Frenkel pairs (i.e. no clusters of production bias model SIAs) can be clearly understood in terms of the standard rate theory and disloca- In the past, the effect of recoil energy tion bias. The analysis of these results on defect accumulation in the form, for yields a dislocation bias of ~ 2 %. example, of voids has not been treated explicitly. An examination of the literature reveals two main reasons for this Effects of various heat-treatments limitation. First, the vital information and irradiation on mechanical prop- regarding the details (e.g. nature, effi- erties of copper alloys ciency and morphology) of defect pro- Precipitation and dispersion strength- duction as a function of recoil energy ened copper alloys (CuCrZr, CuNiBe and

did not become available until rather CuAl2O3) are being considered as heat recently. The second reason is related to sink materials in the first wall and the fact that the earlier theories were divertor assemblies of ITER because of based on homogeneous kinetics and their high thermal conductivity and mean field approach and were unable to high strength. The joining procedures treat the problem of defect accumulation employed to fabricate the structural under the condition when both glissile components of the first wall and the and sessile clusters of self-interstitial divertor may influence the performance atoms (SIAs) were generated at higher of these materials during irradiation. In recoil energies. Furthermore, up to a order to evaluate the effects of bonding certain level of recoil energy, both the and bakeout thermal treatments on pre- damage efficiency and the amount of and post-irradiation properties of these An assembly of five 25 keV cascades containing clusters of vacancies (green) and SIA clusters produced during irradiation alloys, a series of screening experiments SIAs (red) 10 picoseconds after the colli- depends strongly on the damage energy. were carried out. A number of tensile sion event during MD simulations (top specimens of CuCrZr and CuNiBe alloys picture). After stochastic annealing at 450 The recently proposed 'production Kfor one nanosecond, the SIA population bias model' (PBM), on the other hand, is were given different heat treatments to consists of only sessile clusters (middle fully capable of treating the problem of simulate the effect of joining and bake- picture) whereas after annealing for 100 out thermal treatments. The heat trea- seconds (bottom picture) only large clus- intracascade clustering of SIAs and the ters of SIA and vacancies remain. glide of SIA clusters. In fact, one of the ted specimens were irradiated in the DR3

17 at relatively low temperatures become level dislocation sources remain locked. significantly harder, suffer from plastic At the upper yield stress, a number of instability and lose ductility. It is the dislocation sources begin to operate and loss of ductility, commonly known as form 'cleared' channels. In other words, embrittlement, which is a matter of the plastic deformation is localized and serious concern from the point of view occurs only in these cleared channels. of the lifetime of structural components The analysis of the present results sug- in fission or fusion reactors. Because of gests that during irradiation under this concern, the effects of irradiation cascade damage conditions, gliding SIA on deformation behaviour of metals and clusters block the dislocation sources alloys are being studied internationally. and thus prevent homogeneous plastic Tensile specimens and 3 mm diam- deformation. Consequently, the crack eter discs of monocrystals of pure mo- nucleation is no longer caused by plastic lybdenum and Mo-5%Re alloy were irra- deformation. Instead, the crack must diated in helium-filled capsules with initiate at internal and/or external flaws fission neutrons in the DR3 reactor at in the material. The interaction of these Ris0. Irradiations were carried out at ~ cleared channels with external surfaces 50 °C to displacement doses in the range or grain boundaries or intersections of Post-deformation microstructure of monocrystal- 5.4 x 10"4 to 1.6 x 10"1 dpa. For compari- these channels with each other may line molybdenum irradiated with fission neutrons at 320Kto a dose level of 5.4 x 103 dpa. Note son, polycrystalline specimens were also initiate cracks. Once initiated, the crack the evidence of localized deformation in the form irradiated. Post-irradiation microstruc- is likely to propagate rapidly through of 'cleared' channels. tures were quantitatively characterized the material since the irradiated mate- using TEM. Both unirradiated and irradi- rial is unable to deform plastically in a ated specimens were tensile tested at homogeneous fashion. ambient temperature. The microstructure of the irradiated and deformed Electrical conductivity of iron, copper specimens was also examined using TEM. and copper alloys

reactor at Ris0 at 100 °C to a displace- Monocrystals of both pure Mo and Cu-Al203 (with 0.25 % Al, CuAl25) has ment dose level of ~ 0.3 dpa. Both unir- Mo-5%Re alloy suffer from plastic insta- been chosen as prime candidate for the radiated and irradiated specimens were bility in the same way as the polycry- first wall and divertor material in ITER tensile tested in vacuum at 100 °C. stals. The occurrence of plastic instabil- and CuNiBe and CuCrZr as potential The irradiation of CuCrZr at 100 °C ity suggests that up to a certain stress backup materials. Electrical conductivity caused a drastic reduction in the uniform elongation and led to plastic instability (localization) almost immediately after the initiation of plastic deforma- 102 The electrical conductivi- Cu Fe tion. The CuNiBe and the CuAl2O3 speci- 100 ties of neutron irradiated 100 50 copper and iron, relative to mens suffered too from an irradiation- As-irradiated • 98 Ann. 300°C/50h • the conductivities for the induced reduction in the uniform elon- a A un-irradiated materials as gation, but to a lesser degree than the 96 A-"' a function of irradiation CuCrZr specimens at the same dose level. dose. Data are shown both 94 for the as-irradiated state The prior irradiation treatments corre- and after annealing at 300 sponding to the joining and the bakeout 92 °Cfor 50 hours. The clearly thermal treatments did not lead to any •o different behaviour of the o 90 two materials is ascribed to improvement in the mechanical and differences in crystal physical properties after irradiation. O 88 structure and impurity | content. 19 86 Effect of irradiation on deformation CD OH 84 behaviour of metals and alloys It is well known that metals and alloys 82 exposed to radiation with energetic 80 particles (e.g. fission or fusion neutrons) 0.01 0.1 0.5 Dose (dpa)

18 Techniques

measurements were carried out on these The success of the projects within the synchrotron radiation experiments are alloys and pure copper after different programme area depends on the efficient conducted at HASYLAB, Hamburg and initial heat treatments, fission neutron use of a number of different experimen- ESRF, Grenoble. irradiation at different irradiation tem- tal and modelling techniques. The mod- The programme area also utilizes a peratures, and post irradiation anneal- elling techniques are rather diversified number of experimental techniques ing. The treatments simulate the possi- with specific techniques used in the managed by other programme areas, ble histories of the material in ITER. individual projects, ranging from closed- particularly mechanical testing and X- In CuAl25, the conductivity was form matematics to advanced numerical ray diffraction. found to be 88 % of that of pure copper. methods (e.g. for solving non-linear Irradiation to 0.2 - 0.3 dpa reduces this problems), which require extensive X-ray spectrometry in the environ- number to 81 %, irrespective of irradia- computer power. For instance, microme- mental scanning electron microscope tion temperature. Annealing at 300 °C chanical models are used for providing a The presence of gas in the specimen changed these values only slightly. For direct relationship between the geom- chamber of the ESEM causes the primary Cu-Al203 (0.6 % Al) the reduction due to etry of the microstmcture and the electrons to be scattered on their way the alloying was down to 79 %, but the macroscopic mechanical behaviour of towards the specimen. The skirt of effect of irradiation was smaller. materials. scattered electrons generate X-rays far The electrical conductivities of the The experimental techniques man- from the electron beam target. This unirradiated and irradiated (0.3 dpa) aged within the programme are summa- leads to a deterioration of the spatial CuCrZr and CuNiBe alloys fell in the rized in the following table. Many of the resolution for chemical analysis by X-ray range of 50 - 80 % and below 55 %, techniques are also used in a number of spectrometry. Two methods to overcome respectively, of the conductivity of pure projects from other programme areas. this problem were described in the copper. Generally, irradiation was found The techniques are not just brought in. previous annual report. to cause an increase of the conductivity The development of methods and equip- The pressure variation method is of CuCrZr. For CuNiBe it increased at 350 ment is a research topic in its own right, based on spectra being measured at the °C, but decreased for lower irradiation as described below in separate sections. same beam target at a number of differ- temperatures. By subsequent annealing The Department has two transmis- ent pressures. These measurements are the conductivity always increases. The sion electron microscopes and three then used to extrapolate to the measure- results correlate well with data obtained scanning electron microscopes. Neutron ment that would have been obtained by electron microscopy and mechanical diffraction experiments are conducted at under high vacuum conditions. The testing and can be ascribed to effects of the DR3 research reactor at Ris0, while method was improved by the introduc- (i) cascade-induced dissolution of precipitates by cascade impingement, (ii) segregation of alloying elements and (iii) reprecipitation. In pure copper the conductivity decreased with irradition dose, and annealing at 300 °C for 50 Method Objective hours led only to a partial recovery of Characterization : Transmission electron microscopy Microstructure, local crystallographic the radiation created defects. Technique? ^ i (TEM); EDS and EELS orientation, local chemical composition

• • .. •; • :.-:. ' • .' • Iron irradiated at 50 °C showed a Scanning electron microscopy Microstructure, local crystallographic decrease in conductivity to 86 % of the (SEM); EBSP, COM, EDS orientation, orientation maps, local value for un-irradiated iron even at a chemical composition low dose. Only a small further decrease Environmental scanning electron Microstructure, local chemical composi- to 83 % was observed up to 0.23 dpa. microscopy (ESEM); EDS; high tion, in-situ investigations of insulators For irradiation at 100 °C, the conductiv- temperature, mechanical testing and wet materials '• '. •- '•. ity decreased from 99 % to 92 % in the (tension/compression/bending/ :•• •: controlled crack growth) same dose range. This large difference in behaviour probably reflects the migra- Neutron diffraction; elevated In-situ measurements of texture and .' .• ' •-: .. ..;.'.:- temperature tensile testing internal strains tion of carbon impurities between 50 °C ': •"'' .•-•;- •''" •- and 100 °C and illustrates the sensitivity Synchrotron radiation; ambient Local erystallographic orientation (3D), of the electrical conductivity to impuri- and high temperature local strain state ties and the defect microstructure. Positron annihilation Point defects, line defects, free volume, spectroscopy (PAS) interfaces and gas bubbles

19 tion of a new extrapolation procedure • which accounts for the uncertainty of the individual measurements. It has been shown experimentally that the correct result in most cases lies within one standard deviation from the ex- trapolated result when the new extrapolation procedure is used. The beam stop method was developed for use with line scans. The specimen is covered with a foil along the bine where a line scan is desired. The spectral measurement in a point close to the foil is corrected for beam skirt effects by a corresponding measurement at a point on the foil close to the first point. It was shown experimentally that the spatial resolution in the line scan can be restored to about 10 (xm by this method. An EBSPfrom recrystallized pure copper. The 15 triplets of coloured lines The reason that the spatial resolution illustrate the position and width ofKikuchi bands which were detected automatically by a novel pattern recognition procedure. A high precision cannot be completely restored to the of the band positions and of the measured band widths is observed. high vacuum value is that there is an intense skirt component of inelastically scattered electrons just around the unscattered beam, and this component is sensitive to a movement of the beam around 0.5 |xm in the SEM. The recent The reliability and accuracy of the by a few micrometers. development of specialized image analy- EBSP technique are strongly dependent sis procedures for automatic recognition on the reliability and precision by which Advancements of the EBSP technique of linear features in the patterns, the the Kikuchi bands are found by the Electron backscattering patterns (EBSPs), Kikuchi bands, has led to a complete image analysis procedure. In an effort to also known as backscatter Kikuchi pat- automization of the technique and made improve the quality of the automatically terns, are electron diffraction patterns it an extremely powerful tool in studies collected crystal orientation data a new from which crystal orientations can be of the orientational aspects of micro- procedure was developed for this band measured with a spatial resolution of structures in crystalline materials. detection task. This novel procedure provides significant improvements to the precision by which the bands are localized, and is generally capable of identifying a larger number of bands than the traditional approach. Additionally, the new procedure also provides reasonably precise measurements of the width of the band which may be utilized for improving the reliability of the measurements even further. We have shown that the new procedure leads to significant improvements in both the reliability and precision of the automatically measured crystal orientations. The best obtainable precision is around 0.7 ° with the tradi- 300 400 500 700 pressure (Pa) tional procedure whereas 0.4 ° can be achieved with the new procedure. Extrapolation by the pressure variation method. The counts per second for CuKa were measured at various pressures in a point in pure Ni 10 |jjn from an interface to pure Cu. The extrapolation yields 0.64 ± 0.71.

20 Image

Optics for a three dimensional X-ray plane microscope The Department is collaborating with ESRF on the installation of a three- dimensional X-ray microscope (3DXRD) at the synchrotron. The microscope will be dedicated to characterization of materials locally within millimetre thick specimens. Parameters such as strain, grain orientations, grain morphology Slit and dislocation densities are to be inves- Multilayer tigated in-situ, that is during an annealing or deformation process. The instru- Beam stop ment is to operate in the energy range 40 -100 keV with gauge volumes of Laue Sample order 5 x 5 x 50 (jtm3. Monochromator To meet specifications, novel types P q of X-ray optics must be designed. In -H- particular it is necessary to reconsider the way depth-information is obtained. This is conventionally done by means of The incoming beam is focused by a Laue monochromator - a bent per- cross-beam techniques, where both the fect crystal. Next, a bent multilayer with a lateral grading is used to also focus the diffracted beam. The multilayer has the property that incoming and the diffracted beams are diffracted rays from one point A in the sample will all converge in a confined, typically by collimators. Un- spot A*, while rays from another point B will converge in B*. In short, fortunately, collimators are very difficult a line through the depth of the sample is projected onto an image plane transverse to the diffracted beam. By changing distances p and q, the to manufacture for the 3DXRD case and magnification ratio of q/p may be optimized. they do not allow an efficient focusing of the incoming beam. An alternative set-up, giving superior depth-resolution without any of the problems associated with the use of collimators, was developed. The properties of this set-up were tested - by a Ris0/ESRF/SLS (Swiss Light Source) team - at 30 keV at beamline D5 at ESRF. Results showed that theoretical predictions for resolution, magnification etc. were matched by experiment.

21 MATERIALS CHEMISTRY - combining science and technology

The Materials Chemistry research area consists of two programmes: Fuel Project Funded Research: Materials Chemistry cells and high-temperature supercon- Project type Project name Co-participants ductors. Both programmes deal with synthesis and processing of ceramic The Energy Research DK-SOFC 1996-1998 • Haldor Topsae A/S, Denmark Programme of the • Innovision A/S, Denmark materials (oxides). The understand- Banish Ministry of 1 Institute of Chemistry, OU, Denmark ing of phase relations arid defect Environment and • Institute of Chemistry, DTU, Denmark Energy (EFP) chemistry is very important in both areas. Solid state electrochemistry is EFP SOFC Module Design • Haldor Topsae A/S, Denmark

of particular importance for the fuel EFP DK Superconductors « NKT Cables A/S, Denmark cell programme. • NKT Research Centre A/S, Denmark • Inst. of Product. Techology, DTU, Denmark • Electric Power Eng. Dept., DTU, Denmark The fuel cell R & D concentrates on • Research Assoc. of Danish Electric Utilities • Condensed Matter Physics and Chemistry solid oxide fuel cells (SOFCs). Many Department, Risa results were obtained. As highlights JOULE-THERMIE Improving Durability of • Research Centre Julich, Germany one can mention (i) the development SOFC Stacks (IDUSOFC) ' ECN, Petten, The Netherlands of Ni-based anodes, having a polari- • Imperial College, University of London, UK • University of Oslo, Norway sation resistance of cathodes of only * Siemens GmbH, Germany ~ 0.1 fkm2 at 850 °C, (ii) the devel- • Haldor TopsBe A/S, Denmark > Rolls-Royce, UK : opment a new cell design concept, > Statoil a.s., Norway (iii) the efforts of fundamental BRITE-EURAM Low Cost Fabrication and • Innovision A/S, Denmark research on metal oxides with Improved Performance of • Rolls-Royce, UK perovskite structure, and (iv) the SOFC Stack Components > INPG, France (LOCOSOFC) Gaz de France, France work on high temperature oxidation • NUVL, UK of Fe-Cr-alloys, aimed at identifying EPFL, Switzerland

the most suitable compositions for New Energy Advanced Ceramics Nagoya University, Japan metallic SOFC-stack and -system Development for Protonics " Touhoku University; Japan Organization, Japan University of Pensylvania, USA components. (NEDO) University of Missouri-Rolla, USA 1 Research Centre Julich, Germany TYK Corporation, Japan In the area of high temperature superconductors the following highlights can be mentioned: (i) a technique was developed for routine manufacturing of single filament tapes by means of rolling, (ii) the construction of a dedicated X-ray set- up at the HASYLAB synchrotron in Hamburg for in-situ studies of tapes was completed, (iii) the establish-

ment of a (F, /?02)-phase diagram, and (iv) the critical current density was increased by 35 % by cooling the tapes in an atmosphere with the oxygen partial pressure reduced to 7% (instead of air).

22 Current flow direction

Fuel cells

Repeating / The overall aim of Uniit \ this programme is to establish a basis for a Danish produc- Air flow direction tion of SOFC components and to ex- plore the potential of SOFC in the Danish energy system. The programme consists of three parts: (i) Solid state chemistry, where the scientific diciplines are crystallography, defect chemistry and solid state electrochemistry (electrode kinetics, conductivity of solid electrolytes), (ii) characterization of powders, electrode properties, conductivity, struc- Fuel flow direction ture of composites (electrodes), mechanical strength, cell and stack per- SOFC cell stack of the bipolar flat plate design. formance, and (iii) fabrication of The repetitive unit consists of two rigid ele- electroceramic components to reduce ments, the SOFC cell comprising anode, electro- cost and to obtain optimal properties. lyte and cathode, and the interconnect or bipolar plate, providing gas separation, gas channels and electrical contact between cells. Improved performance of solid oxide End'96 End '97 Prospektive fuel cell components leads to a new Achieved and prospective SOFC approach cell resistances in the Danish SOFC project compared on a Different designs of SOFC stacks are relative scale at 850 "C. The pursued world-wide. The bipolar flat contributions are electrolyte resistance, Sp cathode resist- plate design has, among other features, ance R. and anode resistance R,, a minimum current path with minimum ohmic losses, and has been selected for the Danish SOFC programme. Recent developments made at the the mechanical strength of the cell. As a Over the last few years the develop- Department have reduced the electrode consequence, a new approach is taken ment of SOFCs for commercial use has losses in the cell significantly. These where the cell is built with a 1 - 2 mm reached a state where cost analysis is improved electrodes now make it possi- thick porous anode, which provides the being used for identifying components ble to achieve electrode resistances at mechanical strength of the cell and acts and processes which must be substituted temperatures of 800 - 850° C matching as a support for a thin electrolyte. The or modified to meet market costs of values, previously achieved at 1000 °C. electrolyte thickness is expected to be competitive technologies. The overall Exploitation of this reduction in tem- reduced to 30 - 40 |xm, leading to a cost of electricity produced by SOFC perature in a complete cell leaves the factor 5 reduction of the electrolyte stacks has been linked directly to the resistance of the about 180 fj,m thick resistance. internal resistance of the stack, compris- supporting YSZ electrolyte as the major The cost of a mm-thick dense ce- ing reaction resistance in the electrodes contributor to the internal resistance. ramic or oxidation-resistant metallic and ohmic resistance in electrolyte, Significant reduction of this resistance interconnect with a machined gas distri- interconnect and contacts between may be achieved by a thickness reduc- bution structure on both faces is pro- components. tion, which unfortunately diminishes hibitive for SOFC commercialization. A significant cost reduction can be obtained by splitting this component into several functional layers. Combined with the temperature reduction made avail- SOFC Component Material able through better electrodes, the Electrolyte Yttria stabilized zirconia (YSZ) : interconnector material can potentially Cathode Lanthanum strontium manganite (LSM) be made from commercial FeCr alloys Anode Nickel- YSZ-cermet ... Interconnect Lanthanum strontium chromite (LSG) and/or chromium metal alloy rather than from high cost ceramics and special alloys.

23 Oxidation of H2at the interface using anodes, but has to be converted via trode is often introduced to measure the a proton conducting oxide steam reforming to hydrogen and carbon losses associated with the individual In SOFCs based on oxide ion conducting monoxide, which can then be electro- electrodes. A small oscillating voltage is solid electrolytes, the products of fuel chemically oxidized in the fuel cell. The applied between working and reference oxidation are evolved at the anode. In high operating temperature of the solid electrode. The resulting current is meas- an alternative cell design, based on high oxide fuel cell allows the steam reform- ured and the impedance of the electrode temperature proton conducting electro- ing process to take place inside the determined as a function of frequency. lytes, the fuel is hydrogen and the stack (internal reforming). Practical Interpreting the impedance spectrum product, water vapour, is evolved at the realization of internal reforming, how- and deriving information about the cathode. The oxidation of hydrogen at ever, poses some problems. Ni is a good electrochemical process from such ex- the interface of a metallic electrode and steam reforming catalyst and on a Ni/ periments is not trivial. When current the proton conducting perovskite YSZ anode the steam reforming rate is flows through the cell, hydrogen is

Sr Ce Y 0 WSS StUdied at 600 much higher than the reaction rates of consumed and water produced at the 0.995 o.« 0.05 2.975 *° 800 °C in hydrogen containing atmos- the electrochemical processes. Therefore, anode (vice versa upon reversal of the pheres, conditions relevant to SOFCs. the endothermic steam reforming proc- current). This results in a variation in Under anodic polarization different ess and the exothermic electrochemical gas composition above the anode. Nor- metals showed significant differences in oxidation processes may be very un- mally this variation is neglected in the the kinetics of hydrogen oxidation. evenly distributed over the stack volume analysis of the impedance spectra. Nickel, a preferred anode material for resulting in a very inhomogeneous However, a change in gas composition most SOFC systems, gave the highest temperature distribution. This reduces gives rise to a change in Nernst poten- current densities. Nickel, platinum and, stack efficiency and may even result in tial measured against a reference elec- to a lesser degree, silver displayed high mechanical failure. trode in a stable atmosphere. Therefore, activation energies for hydrogen oxida- From a 3D model of the heat, mass an impedance may be associated with tion. Gold, a relatively inactive material, and charge transfer processes, it was the gas conversion. This effect is in fact displayed a low activation energy. Work possible to identify what area specific the source of the dominant semicircle is continuing to determine whether reaction rate of the steam reforming rate observed at low frequency in the imped- these differences can be related to the is optimal. In addition, a more detailed ance spectrum of SOFC anodes. A simple energy of adsorption and dissociation of (ID) model of the chemical and electro- model of the impedance related to the hydrogen molecules on these metals. chemical process in the anode was gas conversion was formulated assuming formulated taking into account non- perfect mixing of gasses in the volume above the electrode. The model was able Model studies of internal linear kinetics of the electrode reaction, to account well for the observed varia- reforming in SOFC gas-phase diffusion and effects of parti- tion of the impedance with changes in In SOFCs methane cannot be oxidized cle connectivity. This model allowed a gas composition and gas feed rate. directly on the actual Ni/YSZ cermet study of how the area specific steam reforming reaction rate varies with the The effects of overall cell geometry characteristics of the anode such as Ni- of the three-electrode set-up were also content, porosity, particle size and analyzed. An important result of the 100l:-.•:::.,.. electrode thickness. The model studies analysis is that cells with thin electro- showed that the most effective way to lytes are unsuitable for fundamental reduce the steam reforming rate to a studies of the electrode reactions. Even CM 10 suitable level is to reduce anode thick- small misalignments of the order of half ness to 5 - 10|xm, and that this should an electrolyte thickness of the two I not reduce the electrochemical perform- current carrying electrodes will lead to ance. Model studies of this sort thus severe errors in the determination of the 5= 1 provide guidelines for focusing the work polarization resistance. The constraints on developing electrodes suitable for that would have to be applied on the realization of internal reforming. positioning of the electrodes to realize the usefulness of such thin electrolyte 0.1 Modelling effects of electrode mis- test cells are too stringent for normal Au alignment and gas conversion SOFC electrode development work. Impedance spectroscopy is a popular Limiting anodic current density for four metals, obtained at 800 °C in hydrogen, giving a measure experimental technique for studies of of their performance as fuel cell anodes. reaction mechanisms. A reference elec-

24 1000

500

Example of a calculated potential distribution in the limit of very high frequency in the top part of a three electrode pellet designed for studies of the electrode kinetics of SOFC electrodes. The arrow marked r indicates the position of the reference electrode and the thick solid curve illustrates the position of the equipotential line = r in the limit of very low frequency (DC). A small change in the distribution is observed going from the high frequency limit to the low.

Materials for oxygen High-temperature superconductors separation membranes Ceramic membranes with mixed electronic and oxygen ionic conductivity can be utilized for (i) removal of oxygen The programme aims at forming a basis Development of texture and progress from inert gases, (ii) massive oxygen for utilization of high-temperature of phase transformation during an- production and (iii) conversion of meth- superconductors in the Danish electric nealing in superconducting tapes ane to CO + H2 without diluting the power sector. At present the technologi- Despite much effort the structural ef- produced syngas by atmospheric nitro- cal possibilities for utilization of super- fects of the two annealing cycles nor- gen. Such devices are planned to operate conductors in power transmission and mally applied to the BiSCCO/Ag tapes in the temperature range of 500 to 900 power distribution are investigated with are still poorly understood. In particular, °C. As they are pressure driven they focus upon fabrication and characteriza- the origin of the crucial texture develop- need no external electrical driving force. tion of superconducting high power ment of the BiSCCO grains (c-axis align- The concept thus shows great industrial cables. Establishment of a fundamental ment) and the solid state transforma- potential. understanding of the mechanisms re- tions are debated. The Department is Experimental work was initiated on lated to texturing and phase conver- collaborating closely with NKT Research four compositions in the perovskite-like sions, required for the establishment of Centre and the Department of Solid superconductivity, is combined with the State Physics and Chemistry at Ris0 in structure series Sr4Fe6 xCox013±s. A defect model explaining the equilibrium prop- development of new fabrication tech- an attempt to model these phenomena erties was formulated. The observed nologies with a potential for industrial in order to optimize the annealing thermogravimetric data are in agreement scaleability to improve critical current processes with respect to time, tempera- with the defect model. Approximate densities and decrease manufacturing ture, T, and oxygen partial pressure, pO2. values for the two equilibrium constants costs of superconducting tapes. For structural characterization a series (including their temperature dependence) that describe the defect chemistry were determined. A conductivity relaxation method was developed in order to investigate diffusion of oxygen through the ceramic. The model includes a l'st order Elements of high temperature superconducting tapes surface reaction. A powerful numerical least-squares recipe was developed, Explanation Composition based on a universal numerical solution to the transcendental equations (includ- BiSCCO '' " Generic name of ceramic Bismuth-Strontium-Calcium-Copper-Oxide family of compounds with ing the 8'th term), entering the diffu- HTSC properties sion equations. Diffusion coefficients as 4 2 : high as 10" cm /sec were encountered. Bi-2212 Compound of the BiSCCO family Bi!Sr,Ca,Cu!Ox- .

Permeation experiments with real mem- Bi-2223 Compound of the BiSCCO family Bi2Sr2Ca2Cu3Oy . branes are planned. Plumbates'and Secondary phases. React ex. (Ca,Sr),PbO4, / Cuprates Bi-2212 to Bi-2223 during CaCuO , :':• :.. fabrication of HTSC-tapes

25 of complementary techniques are used: synchrotron radiation, laboratory based X-ray diffraction, scanning electron microscopy, and measurements of the critical current densities. The synchrotron technique is based on a unique set- up at the synchrotron laboratory HASYLAB in Hamburg. Using high energy X-rays this set-up allows in-situ investigations of the superconducting powder inside the Ag cladding. The major results obtained so far relates to the first annealing cycle: (i) The texturing mainly takes place during heating, and is related to grain growth of Bi-2212, which is drastically increased

upon the dissolution of (Ca,Sr)2Pb04. The c-axis alignment of Bi-2223 is essen- tially constant during time and to a first approximation identical to the final alignment of Bi-2212. (ii) Upon dissolu-

tion of (Ca,Sr)2Pb04 a CaCuO phase is produced. The Bi-2223 phase is a result of a reaction of this phase with Bi-2212.

In some parts of the (T, pO2) phase diagram an intermediate phase comprising a stacking of Bi-2223 and Bi-2212 unit cells was observed. This provided clear evidence that the reaction takes SEM micrographs of (top) a quenched tape: the microstructure formed at place by means of an intercalation the high temperature heat treatment has been 'frozen in', and (bottom) process. A sparse (T, pO2) phase diagram a slowly cooled tape. The size and total amount of non-superconducting was mapped. At higher temperatures a secondary phases (black and white phases) are larger during slow coating due to the decomposition of Bi-2223 phase. series of eutectica were identified.

Annealing of BiSCCO tapes at reduced

oxygen partial pressure other phases have substantially de- (e.g. 02 concentrations decreased from The main superconducting phase of creased or become negligible and that a the 21 % in air to 7 %), increase the BiSCCO, the Bi-2223 compound, is for- large electric current can be carried maximum superconducting current that med by the reactions of many secondary without resistance by the wire or tape. can be carried by the standard tape from phases during repeated heat treatments Laboratory experiments were carried out 20 to 27 A. The results are being imple- in a very narrow temperature range at the Department in collaboration with mented industrially to improve the around 830 °C and it loses stability NKT/NST, the Danish manufacturer of characteristics of the superconducting during cooling. It is fortunate that superconducting tapes. The results show tapes. research results obtained the world over that: (i) The concentrations of the in the last few years have proven that secondary phases are quite small during heating under reduced oxygen partial the heat treatments at high temperature pressures increases the stability range and they increase during cooling in air and the Bi-2223 phase can be cooled to (SEM and X-ray diffractograms have been low enough temperatures for the decom- used at the Department to identify and position not to take place. estimate the concentrations of the A proof that the Bi-2223 forms secondary phases present at high and under the best conditions is given by low temperatures), (ii) Heat treatments the fact that the concentrations of the in reduced oxygen partial pressures,

26 Techniques

A number of advanced techniques are used within the programme area. The methods for characterizing defect chemistry are thermogravimetry, differential thermal analysis and differential scanning calorimetry. Phase-changes are identified by dilatometry (volume change), diffraction of conventional X-rays or synchrotron radiation (changes in crystallographic lattice parameters). Since the electrochemical activity of the electrodes is very important, several methods are used for electrical measurements under controlled atmosphere and temperature. Electrical conductivity measurements are performed in the temperature interval -196 °C to 1050 °C. Almost all characterization techniques available at the Materials Re- composition, structure, texture and mechanics modelling of stress distribu- search Department are used within this morphology, (ii) mechanical testing tion and fracture mechanics analysis. programme area. Examples of techniques (stiffness, fracture toughness and The fact that so many methods and belonging to other programme areas are strength), (iii) non-destructive evalua- disciplines are used in these projects (i) electron microscopy methods (EDS, tion (detection of flaws in SOFC compo- reflects a main feature of the strategy, EBSP, etc.) for characterizing chemical nents, quality control) and (iv) solid namely to characterize the materials and the components as detailed as possible, in order to support the technological development. Another important consequence of the strategy is the availability of many shaping methods (and skills in Method Objective using them) that makes it possible to Ceramic Shaping Tape casting/spraying/screen Fabrication of samples, make samples with pre-determined printing/dip coating/cold components and devices isostatic pressing characteristics for the scientific studies. Mathematical models of the proc- High shear rolling/profile . Deformation, texture rolling/planar rolling generation esses in an operating SOFC, or in a stack of cells, may be valuable tools in the Grinding by diamond tools Machining of specimens development and testing of SOFC stacks. and components Such models may be used for analysing Characterization Light scattering Particle size distribution the consequences for cell or stack per- Techniques Thermogravimetry/differential Characterization of formance of various changes in the cell thermal analysis/differential solid state processes or stack design. Another use of such . scanning calorimetry models is in the specification of the Dilatometry Volume changes as function properties of the individual components of oxygen partial pressure in the stack (anode, cathode, electrolyte and;temperature, sintering characteristics and interconnect). This kind of information is very important in the search for X-ray diffraction/ Phase;characterization, new and better materials, i.e. it defines synchrotron radiation 'changes in lattice parameters the targets for the researcher. The mod- Impedance spectroscopy/ Electrical conductivity, elling methods that are used are mainly van der Pauw DC/classical electrochemical activity 4 point DC the finite volume method (modelling of heat, mass and charge transfer) and FEM Direct current vs. voltage SOFC performance, critical (integral SOFC stack modelling and mi- (chrono-amperometric and current density potentiodynamic) cromodelling of SOFC electrodes).

27 MATERIALS ENGINEERING - modelling and performance

The activities within Materials Engi- neering as described in the following Project Funded Research: Materials Engineering sections have been focused on material properties for design application, Project type Project name Co-participants materials engineering, related mate- Danish Research Councils Natural Fibres for > Royal Vet. and Agricult. University, Denmark rials characterization and testing as Polymeric Composites >.. Inst. for Constr. and Materials, DTU, Denmark

well as component design. ••:•••• .: • . :•• :. EFPv ,'V '; . Windturbine Blade Design « LM Glasfiber A/S, Denmark 1 Vestas A/S, Denmark The activities are presented in two > ELSAM, Denmark • Wind Energy & Atmospheric Physics Dep. Risa sections, Design and Mechanical > Dept of Fluid Dynamics, DTU, Denmark Testing, which concerns both compo- EFP : : Flywheel for Energy Storage <> Per Udsen Co., Denmark nent design and engineering materi- for Add-on-Armour <• NESA A/S, Denmark als, and Properties of Advanced Com- > DEMEX A/S, Denmark

posite Materials, which covers charac- EUCLID ' Advanced Techniques for <> DEMEX A/S, Denmark terization of materials reinforced Add-on-Armour <• DSM, The Netherlands > OTO.Melara, Italy with fibres or particulates. BRITE-EURAM Thixoforming of Advanced > Pechiney CRV SA, France Light Metals for Automotive '> Norsk Hydro Aluminium a.s., Norway The highlights within this area are Components Norsk Hydro (Mg Division) a.s., Norway (i) the studies of microstructure and (TALMAC) < EFU GmbH, Germany Stampal SpA, Italy mechanical properties of natural FIAT SpA, Italy ; fibre composites, (ii) the investiga- Volkswagen GmbH, Germany INPG, Grenoble, France tion of the deformation characteris- University of Ancona, Italy tics of aluminium MMCs for forging, SINTEF, Norway

(iii) the development of a technique BRITE-EURAM Design and Processing of > Daimler Benz GmbH, Germany for measuring bridging laws during Selectively Reinforced > Aerospatiale SA, France Magnesium-based Composites • Blankguss, Germany intralaminar cracking, and (iv) the > GF Automobilguss, Austria development of a highly innovative Unitech, Austria > IMMG, Greece radiographic system for Morgan MT, UK real-time quantita- • EMPA, Switzerland RWTH-Aachen, Germany , tive inspection of ' ILFB/TU Wien, Austria large thickness LKR, Ranshofen, Austria

pipes. BRITE-EURAM Hyper-Eutectic Alloys for • ISRIM, Italy Automobile Components • FIAT SpA, Italy. (HAforAC) • Stampal SpA, Italy > Pechiney CRV SA, France Fagor Ederlan, S. Coop. Ltd., Spain Bosch Systemes de Freinage, France University of Sheffield, UK

Norsk Hydro Aluminium a.s., Norway : ' CEIT de Guipuzcoa, Spain « Allied Signal Bremsbelag GmbH, Germany . ;

BRITE-EURAM Development of a Portable <> Carl Bra Industri & Marine A/S, Denmark Remote Controlled Real-Time <> Kuwait Petroleum Denmark A/S, Denmark Radioscopy System for <> Photonic Science pic, UK Quantitative Industrial <> Thomsen Tubes Electroniques SA, France Inspection of large Thickness <> Sauerwein Systemtechnick GmbH, Germany Steel Pipes and Weldings <> Statoil a.s., Norway (RAYSQINS) < Bundesanstalt flir Materialprufung, Germany Institute de Soldadura e Qualidade, Portugal Institut de Soudure, France

BRITE-EURAM Action for low weight < Rover Group Ltd., UK

automobile technologies < GIE Renault, France : '••'.• (FLOAT) Centra RichercheFIATSCpA, Italy Ranshofen, Austria Frauenhofer, Germany Volvo AB, Sweden ' !:•".. SEPARIS, France . ISRIM, Italy Daimler Benz AG, Germany

28 Design and mechanical testing

This research programme concerns the development of numerical and experimental methods'for design of components with specific emphasis on new materials. The activities include development of advanced non-destructive and destructive experimental methods for mechanical testing and characterization of materials.

Design and manufacturing of 1 kWh flywheel for energy storage The design work on a prototype flywheel system for energy storage has been fina- lized and the manufacturing of components started. The design is based on previous concept studies and patents on the critical connection between shaft and rim, which enables connection to either a mechanical transmission unit or to an electric motor/generator. Test facility for prototype flywheel testing now being established in the Department. The 400 mm diameter, 20 kg carbon/epoxy rim (1) is con- The flywheel was designed for an nected to the thin composite shell element (2), attached to the integral operational nominal speed of 36000 rpm steel disc and shaft (3). The shaft is supported in squeeze film damped ball bearings (4) in the end covers of the evacuated safety containment and 20 - 50 kW power rating. The origi- (5). The shaft is attached to a 6.5/14 kW motor/generator (6). nally planned mechanical transmission had to be abandoned for budgetary reasons. A direct driven motor/generator and converter were chosen instead: a commercial spindle motor for tooling of the connection element. After initial Out-of-plane elastic properties of machines with a maximum speed of test runs in order to verify the rotor- polymer composites 50000 rpm and 6.5/14 kW power rating dynamic behaviour, the system is ex- Thick polymer composite laminates are together with a versatile frequency pected to be operational in the middle used for an increasing number of appli- converter. The motor/generator with of 1998. cations such as wind turbine blades, converter as well as lubrication and cooling system were installed and initial acceptance tests performed. The flywheel rotor is supported on ball bearings and designed for operation Sketch of various compression test prism specimens, cut in the 1 direc- beyond the lowest critical rotor speeds tion (A), the 2 direction (B) and the as a soft rotor. The bearings are sup- 3 direction (C) of a 32 mm thick E- ported in flexible bearing houses in the glass/PET unidirectional composite. flywheel containment house. The flywheel rotor has to be operated in vacuum, whereas the chosen motor/ generator shall be operated under atmospheric conditions. They are connected to each other through a flexible coupling and mounted in a common frame. The composite flywheel rim and connection element was manufactured by a filament winding technique, and additional materials testing was performed in order to verify the properties

29 flywheels and ballistic protection panels. materials for production. Test specimens predict component performance from a Design and analysis of these applications were cut from 1-3 mm thick panels. fast non-destructive inspection. High requires a knowledge of the elastic con- Cyclic tests (uniaxial loading) were contrast and high resolution radiography stants and strength in the thickness carried out 0 °, 10 °, and 90 ° relative to and accurate through transmission and direction (out-of-plane) of the laminate the fibre direction and were performed pulse-echo ultrasonic C-scanning have as well as in the directions of the lami- at frequencies up to 30 Hz. To minimise been applied. The detection limit was nate (in-plane). the testing costs the test frequencies extended from conventional casting Two methods were used for measur- were selected as high as possible with- defects such as voids and cracks of mm- ing the elastic constants of orthotropic out getting effects from internal heating size to groups of micro-porosity. The laminates: A mechanical compression due to hysteresis and damping. The tests latter type of defects, caused by shrink- test and an ultrasonic technique. The are run at -30 °C, at room temperature, age, is present at grain boundaries and compression test requires laminates of and at temperatures up to 120 °C. Creep of 0.1 - 0.2 mm in size. At the current at least 25 mm thickness and uses prism tests on the thermoplastic composites stage, a qualitative relationship between shaped specimens with strain gauges were also performed. Creep curves were NDE data and microstructure has been attached to the four free faces. All three determined both at 25 °C and at 120 °C established. NDE has been applied to Young's moduli and the three Poisson's with loading directions 0 ° and 90 ° rela- qualitatively predict the mechanical ratios can be determined in this manner. tive to the fibre direction. The creep performance of samples, based on the During the ultrasonic testing the speci- tests were conducted for more than 1000 apparent defect population. As an exam- men has to be immersed in water. How- hours under constant load and tempera- ple, of a number of tensile specimens ever, all nine elastic constants of an ture. made from thixoformed AA6082 (alu- orthotropic material can be measured minium-silicon-magnesium) compo- with this technique. Non-destructive evaluation of ad- nents, two specimens which contain Measurements on specimens from vanced light alloys and correlation groups of micro-porosity were unveiled the same 32 mm thick unidirectional with destructive tests and micro- by NDE. The yield strength and tensile composite (E-glass fibres in PET matrix) structure elongation of these two specimens were show a good agreement between the The Department is involved in two reduced by 30 % and 90 %, respectively. methods. The ultrasonic technique is projects on advanced light alloys for non-destructive in nature and gives the automobile components, specifically, Application of high resolution radi- elastic properties for very low strain thixoforming of aluminium alloys and ography on new plant composite levels. In contrast, the compression test hyper-eutectic aluminium-silicon alloys. materials can be used to obtain material proper- One of the main purposes is to establish New advanced composites, made of plant ties at strain levels limited only by the a quantitative relationship between data and wood fibres, are becoming increas- compression strain to failure. As an from non-destructive evaluation (NDE), ingly more attractive for environmental example consider the environmental microstructure and mechanical proper- and political/economical reasons. These degradation with time of a laminate. The ties. The perspective is to be able to materials have proven suitable as re- compression test can be used to characterize the original material in the entire strain range. The ultrasonic technique can be used for the measurement of elastic constants at regular intervals during the environmental treatment. The changes in elastic constants with time can be used as a measure of the degradation of the laminate.

Fatigue testing and creep testing of thermoplastic polymer composites The fatigue behaviour of thermoplastic composites was investigated experimentally. Staircase tests, to determine the fatigue limit at given numbers of cycles Digitized and false colored radiograph of a jute fibre-polypropylene test (e.g. 105 to 2 x 106), were used to obtain bar after strength testing. The predominant fibre orientation is N-S. Note low density spots and patches (blue area) and general sample materials data for design and to validate homogeneity. Width of bar approx. 2 cm.

30 [dB] 30

placements for conventional fibre com- 20 posites as construction materials e.g. in the transport industry. Testing and characterization is important in order to ensure the material quality and perform- 15 ance. NDE, e.g. by radiography, offers a possibility to characterize flaws prior to destructive mechanical testing. The information obtained can be applied to 10 assess the criticality of defects and to establish a performance to quality relationship. At the manufacturing control stage this knowledge can be applied to establish an accept - reject criterion. -10 Initial investigations have been conducted applying high resolution radiography on thin (3 mm thick) ten- 10 sile tests bars made of jute fibres in a X-axis [mm] polypropylene matrix. Low energy radiation (peak energy 20 keV) was used in Reflection tomogram of a cylindrical AlSi-alloy showing: the cross- combination with a slow, fine grained sectional dimensions (15-20 mm), an inclusion and a 2 mm axial hole. High reflectivity is indicated by yellow. film. The film was subsequently digitized in order to secure a high contrast between fibres and matrix. A spatial resolution of a few micrometres was obtained. The digitized image permits receiver of the ultrasonic signal. The gram of the material. A tomogram is quantitative measures to be extracted, amplitude and time-of-flight of the simply a picture of a slice (Tomo comes e.g. void sizes, dimensions of inhomoge- transmitted ultrasonic wave is measured from the Greek word tomos, meaning neous patches and foreign inclusions, during a raster scanning performed in slice, and gram refers to a graphical fibre alignment, etc. However, at the water. High frequency (50 MHz) focused representation). Ideally, this tomogram present stage, results have been applied transducers were used in order to get a contains only an infinitesimal thin two- only qualitatively to monitor the general good resolution. The amplitude of the dimensional cross-sectional plane, with- homogeneity, distribution and direction transmitted signal is damped by defects out any interference from other planes. of fibres. Future work aims at providing such as delaminations and cracks. In the The tomogram may be displayed from a correlation between destructive test present study plates with artificial any desired location and with any de- results and quantitative data from radi- defects (delaminations) were used as sired orientation relative to the speci- ography. calibration samples. Destructive exami- men. nations have verified the capability of Discontinuities in cylindrical AlSi- Non-destructive evaluation the technique to find the defects. alloys were studied by ultrasonic reflec- of solid oxide fuel cells tion tomography. Reflection data were The plates functioning as electrolytes in Ultrasonic reflection tomography acquired by high frequency (narrow SOFCs are only 0.2 mm thick and the Ultrasound computed tomography (UCT) beam) transducers in a synthetic circular thickness of the electrode layers is about is a relatively new imaging technique in aperture array. From these profiles 40 |xm. It is important to ensure that NDE of solid materials. It offers an im- reflection tomograms were constructed the components used are free of large proved characterization of discontinu- using a filtered back-projection tech- defects that can result in mechanical ities (inhomogeneties or defects) com- nique. Straight line propagation was failure or lower the electrical perform- pared with the conventional A-, B- and assumed. Three-dimensional information ance of the stack. Therefore, ultrasonic C-scan technique. (i.e., discontinuity location, dimension through-transmission scanning was used In the UCT-technique, solid materials and type) was obtained by stacking to characterize cells for SOFC stacks. under investigation are insonified by these reflection tomograms in multiple In the through-transmission tech- ultrasound and the reflected (or trans- planes in the third dimension. nique two separate transducers facing mitted) signals are used to reconstruct a each other are used as transmitter and two-dimensional cross-sectional tomo-

31 Properties of advanced composite materials

This research programme concerns the properties of advanced composite materials with either a metal, polymer or ceramic matrix. Focus is on the characterization of microstructure, mechanical and physical properties. Both inorganic Pre-preg and natural fibres are dealt with. 3000 Orientation

Improved methods for stiffness based fatigue diagrams for glass fibre/polymeric composites A»% • A model has been developed for the prediction of the damage evolution of fibre composite materials during cyclic loading. The model predicts the relative stiffness change per cyclic loading at ss H = 10 mm A H = 6 mm given stress or strain levels; the stiffness » H = 4 mm decrease rate is described by a power dependence on the stress and the strain. This relationship allows a constant 1 2 3 4 loading amplitude S-N curve to be de- End-Opening, S* (mm) rived based on experiments by recording the damage. It allows the fatigue life- Schematics showing a DCB specimen loaded with pure bending moments (end-opening of the bridging zone, 8*, is indicated). The measured time to be predicted without running relationship between the crack growth resistance GR and S* is independ- the fatigue test to failure. An interactive ent of specimen geometry, indicating that the bridging law can be testing programme was developed where regarded as a material property. stiffness and damping behaviour can be followed experimentally cycle by cycle. Experiments were performed on carbon, from the outside. Split moulds were Large scale bridging: Measurement glass, and carbon/glass-polyester com- manufactured, and procedures for the of bridging law of fibre-cross-over posites in fatigue tests. Variable load location of the material in the split bridging amplitudes under block loading were mould were established. These consist of Unidirectional laminae have a low resist- also studied. The fatigue damage was unwinding a roll of the material in the ance to cracking in planes parallel with recorded by measuring the stiffness mould, while simultaneously removing the fibre direction. The crack growth changes in the material under this cyclic the peel-off layers. The method will resistance can, however, be enhanced loading. Stiffness controlled fatigue probably produce the best quality tubes significantly by fibre-cross-over bridg- curves were generated and presented in possible from pre-preg material. ing. Large scale bridging was studied S-N diagrams based on normalized Many tubes were produced. They experimentally in a unidirectional car- stress. It was found that the fatigue were subjected to static and fatigue bon fibre/epoxy matrix composite mate- lifetime can be predicted based on testing in torsion. This provided the rial. The experiments were conducted constant load fatigue results, assuming much needed data on the static and using double cantilever beam specimens independence of preceding load history. dynamic shear properties of the material loaded with pure bending moments. For for wind turbine blades. this configuration, in contrast to most Torsion test for determining the Static stiffness values were deter- other standard test configurations, the shear properties of composite mined by strain-gauge measurements. global energy release rate is independent materials These data will be very accurate, if the of the bridging traction from the fibres. A fabrication procedure for the manufac- geometry of the tubes have been deter- For intralaminar cracks a significant ture of high-quality tubes from prepreg mined precisely. However, the fatigue increase in the crack growth resistance material has been established. A prob- properties should be regarded as lower occurred with increasing crack exten- lem in this connection is the thickness limits for a hypothetical material with sion. The increase was attributed to fibre reduction during the consolidation of no end effects, since the location of the cross-over bridging. The R-curve behav- the material, which creates folds in the failure zones is, as expected, influenced iour i.e. the relationship between crack material if the compaction takes place by the unavoidable overlap regions. growth resistance GR and crack extension

32 depended on specimen geometry. There- of the composites were 27 MPa and 55 fore, fibres were characterized by several fore, the concept of R-curves cannot be MPa, respectively. The stiffness and direct and indirect methods. The fibre used as a material property when large strength are comparable to those of morphology was found to consist of scale bridging occurs. The crack opening other natural composites based on PP- approximately equiaxed single fibres of at the end of the bridging zone 8* was matrix and plant fibres, such as flax, diameter of about 20 JJUTI, assembled in measured by extensometers. Utilizing wheat straw, and kenaf, as well as with bundles of 10 - 20 single fibres. The the path independent 3 integral the values for glass fibre/PP composites. fibre density was 1.46 g/cm3. The chemi- bridging law (the relationship between The effect of porosity was evaluated cal composition was about 60 % cellu- the local crack opening 8 and the local from tests at a fibre volume fraction of lose, 12 % hemicellulose, 18 % lignin bridging traction or) was computed from 31 %. The stiffness and strength values and 10 % other substances. The cellulose were found to decrease with porosity content is important for the (potential) content in a steep, non-linear way, crystallinity of the plant fibres, and d8* which is typical of synthetic composites. thereby for the stiffness and strength of The bridging law was found to be inde- The fracture zone of the tensile loaded the fibres. pendent of specimen geometry. A bridg- jute/PP composites showed some fibre The characteristics of the jute/PP ing law can therefore be used as a mate- pull-out, indicating moderate interface composites were used to calculate the rial property in composites with large bonding between (non-treated) jute and properties of the jute fibres, based on scale bridging. The bridging stress was PP. composite theory. From the stiffness and found to be related to the crack opening The long term aim is to fabricate and strength in the 'strong' and in the 'weak' as a oo 8'1/2. This relationship was con- characterize plant fibre/polymer com- direction under tensile loading of the firmed by an analytical model for fibre posites, with the goal of making stiff composites, the orientation-bias of the cross-over bridging. and strong composites of low weight and fibres in the mats was calculated. This with a (potential) biodegradability. gives a deviation from fully random Mechanical properties of jute fibre/ planar orientation (orientation factor polypropylene composites compare Natural jute fibres characterized in 0.33), such that the 'strong' direction favourably with glass fibre/polymeric terms of physical and mechanical has an orientation factor 0.44 , and the composites properties 'weak' direction has a factor of 0.22. Plant fibre composites were manufac- The properties of the jute fibres are of From these results it is possible, tured from jute mats and polypropylene great importance for the properties and based on composite theory, to estimate (PP) foils, and from flax mats and PP- performance of the composites. There- the stiffness and strength of the jute foils. The fabrication was made under pressure in an autoclave where the PP- foils melt and form the matrix. The materials (both composites and fibres) were characterized with respect to microstructure, physical and mechanical properties. The composite density was found to be about 1.0 g/cm3; the volume fraction of jute fibres was 25 - 30 %, and the porosity content was 3-9 %. This rather low porosity indicates a composite of good quality. This was confirmed by non-destructive evaluation based on X- ray radiographs. The mechanical properties were characterized under tensile loading; the stiffness and strength were measured. The jute/PP composites had stiffness values of 3.5 GPa in the 'weak' direction, and of 7.0 GPa in the 'strong' direction. This anisotropy is assumed to Jute fibre/polypropylene-matrix composite, sectioned transverse to the be caused by the fibre orientation in the local fibre direction. The structure and morphology of the jute fibres can be seen. Note, that the lumen of the fibres seems to be filled by jute-mats. The corresponding strengths polypropylene.

33 Techniques

fibres; the value for stiffness is 62 GPa The experimental facilities and methods in connection with mechanical testing and for strength 545 MPa; these values for characterizing the mechanical prop- for damage or failure analysis after are comparable with other estimates. erties of materials are widely used testing. The stiffness is comparable with the within this programme area and in other Extensive modelling of stress and value for glass fibres (70 GPa), and thus programmes in the Department. strain fields of specimens and experi- gives the potential for jute fibre com- The facilities consist of a number of mental set-ups are performed by the posites to match glass fibre composites servo-hydraulic Instron testing frames finite element method for the interpre- in (certain) mechanical properties. (100 and 250 kN) with actuators ranging tation of test results. Likewise, digital from 5 to 250 kN, load cells from 20 N - imaging techniques are used for the Composites of NiTi fibres and 250 kN, strain measuring equipment interpretation and visualization of polyethylene matrix show large shape (strain gauges, extensometers) and results from both radiographic and recovery capability temperature controlled chambers and ultrasonic inspections. The shape active effect in the alloy of furnaces for testing at low and high Techniques from other programme NiTi was used to impose super visco- temperatures (up to 1000 °C). A number areas of the Department are sometimes elastic response in a composite, contain- of load frames for creep testing of metals used in projects belonging to Materials ing NiTi fibres in a polyethylene matrix. and polymers are used. Computerized Engineering. For instance, test speci- The technical interest in such compos- control and data acquisition is used mens are often processed by other pro- ites relates to their potential use as during testing. In some cases commer- gramme areas. Also, characterization of actuators responding to external chan- cial data acquisition programs are used, microstructural damage or studies of ges in stress and/or temperature. while in other cases special programs are fracture surfaces are done by the use of The composites were manufactured developed in-house. SEM. Several mechanical tests may also from NiTi-fibres of diameter 190 y.m and For mechanical testing, both design be conducted in the ESEM, providing a a low density polyethylene matrix by of the test specimen, of the experimen- direct relationship between the evolu- consolidation in an autoclave under tal set-up and of the load introduction tion of damage (observed in-situ during pressure at 150 °C. The content of fibres are crucial. Some tests require specially the tests) and mechanical behaviour. was 8.5 %. The NiTi fibres were heated designed tests specimens and fixtures. A to 450 °C for 30 minutes and quenched number of different grips, specimen Methods for controlling test lapse before the composites were made; this geometries and experimental set-ups Computer programs for controlling left the NiTi fibres in the austenitic have been developed and successfully tensile test machines were developed for condition. used. Thermal imaging and acoustic two purposes: (i) to control the fatigue Unidirectionally reinforced compos- emission systems are routinely used testing of materials, and (ii) to save ites were studied experimentally during during testing, in order to study the data as required during the testing. The a loading/unloading cycle at 60 °C. The evolution of damage. programs are flexible with respect to tensile direction was parallel with the Non-destructive examination by testing cycles (load versus time), and fibres. The loading was continued until ultrasonic or X-ray methods is widely they can calculate the materials re- the austenite to martensite transforma- used for inspection and characterization, sponse, stiffness, energy dissipation etc. tion was completed, which took place at in particular for quality control of with high accuracy during the test. an axial strain of about 6 %. During the manufactured parts or components, and Furthermore, the programs can adjust subsequent unloading the martensitic to austenitic transformation brought the material back to nearly the original 100 The loading/unloading response of length. This demonstrates the large - calculated the shape active composite of NiTi fibres in a polyethylene matrix, viscoelastic shape recovery effect of the measured 80- performed at 60 °C. The large strain composites. shape recovery covers a range of The shape active behaviour of the 60- about 6 %. The theoretical model prediction is shown by the fully composites was described by a model drawn curve. accounting for the stress and temperature dependent transformation of the NiTi fibres and on the viscoelastic behaviour of polyethylene. The model predicts a loading/unloading behaviour which is in good agreement with the experiment.

34 6.0 n=10Hz CT««i=10MPa 5.0

4.0 During cyclic loading, ceramic matrix composites (CMCs) may 3.0 experience temperature rise due to internal heating (sliding Temperature acquisition not started before N-200 C7m«f=230M Pa along fibre/matrix interfaces). The plot shows the temperature ——cycles 2.0 C7r».x=200MPa rise of a CMC as a function of the number of cycles for various applied stress ranges. When the damage state is stable the tem- 1.0 perature rises to a steady-state level (the energy dissipation equals the heat loss). 0.0 10000 20000 30000 40000 50000 Number of Cycles, N the control parameters continuously, for the area of the stress-strain hysteresis toring more complex fatigue behaviour example fatigue testing with constant loop times the cyclic frequency. The and it is aimed at testing structural stress, or constant strain ranges. There strength of the testing technique lies in components with e.g. holes. are no particular requirements to the its capability of detecting hysteresis in test machine, so the programs can be materials with low thermal diffusivity High energy real-time used in combination with most testing like ceramic and polymeric composites. radioscopy detector machines of the Department. In these cases the technique of detect- Within the framework of an EU-funded ing hysteresis from temperature rise industrial R&D a new and versatile Isothermal chamber for measurements gives a resolution higher quantitative 7-radioscopic inspection mechanical testing than the detection limit of conventional system was developed. The system con- During the last three years the Depart- strain measurements. sists of (i) two different high-energy and ment has worked on establishing a The technique is also well suited for high performance radiation imaging mechanical testing facility capable of monitoring long-term fatigue tests as detectors, (ii) a versatile and rigid robot quantitatively measuring the amount of the time-temperature relationship re- unit aimed at inspection of major pipes internal heat generated within a test quires much less storage capacity than and (iii) an expert system driven compu- specimen due to cyclic loads. Several the stress-strain data. Then, significant ter control with integrated procedures gripping arrangements and testing changes in temperature can be used for for flaw sizing and image processing. geometries have been implemented and triggering stress-strain acquisition, as Ris0, which is coordinating this research the technique is now a part of the changes in the shape of the cyclic project, is also responsible for the main standard mechanical testing facilities in stress-strain curve are usually more part of the procedures for quantitative the Department. Emphasis has been on informative with respect to evaluating image analysis, allowing improved per- testing unidirectional and woven fibre- details of the material degradation. ceptibility and size determination of reinforced ceramic matrix composites. Another feature of the technique is the flaws. The procedures are basically These systems develop internal heating capability of continuously detecting developed on two approaches: (i) the due to frictional sliding between fibres temperature distributions and thus measurement of the remaining wall and matrix. The amount of heat gener- damage development with an infrared thickness of pipes, based on profiles ated per second can also be measured as camera. This gives a possibility of moni- across the pipe tangential section, and (ii) an innovative approach which makes use of a priori information of the pipe in order to correlate radiation attenuation Method Objective with wall thickness variations. The Characterization Static tensile/compression/ Elastic constants, stress-strain developed procedures have proven Techniques torsion tests behaviour, strength, creep highly efficient and thickness of the Dynamic tensile/compression/ Fatigue behaviour, damage pipe walls was determined with an torsion tests development, damping properties accuracy of 4 % for the tangential measurement technique (type (i)) and ap- Fracture mechanics testing Fracture toughness, fatigue crack propagation proximately 10 % for type (ii). The procedures are required to promote the Acoustic emission Crack initiation, crack growth, damage development use of electronic imaging systems in radiographic inspection, since new Thermography In-situ detection of damage detectors do not, as radiographic film, evolutipn by temperature rise permit manual ruler-based measure- Ultrasonic scanning Detection of flaws, elastic constants ments of image details. The central issue

Radiography . Location of flaws, porosities, in this context is to achieve an improved water content, etc. inspection efficiency and an improved reliability of quantitative radiographic Data Analysis and Digital imaging Radiography, ultrasonic scanning Presentation condition monitoring.

35 MATERIALS TECHNOLOGY - synthesis, processing and product

Many projects described under this heading are conducted in collabora- Project Funded Research: Materials Technology tion with industrial enterprises in Denmark and abroad. Consequently, Project type Project name Co-participants

the majority of projects have a stra- Danish Agency for Centre for Powder Danish Steel Works Ltd., Denmark tegic character with goals usually not Trade and Industry, Metallurgical MMC-Materials Roulunds A/S, Denmark Centre Contract (COMPOMET) Norsaenk-Aalykke A/S, Denmark more than three years ahead. Very A/S Hartfelt & Co., Denmark often materials technological activi- Scan-Visan A/S, Denmark Danish Technological Institute (DTI), Denmark ties in the Department are initiated by needs or problems encountered in MUP Electro-Ceramic Functional Ferroperm Components, Division of Graded Materials AMP, Denmark industry, but conceived to be better Haldor Topsae A/S, Denmark solved in the research environment PBI-Development A/S, Denmark in the Materials Research Depart- Chemical Institute, KU, Denmark ment. MUP New Alloy Systems for Grundfos A/S, Denmark Corrosion Resistant Powder Danfoss A/S, Denmark Materials Ferritslev Jemvarefabrik A/S, Denmark The area also covers more fundamen- Dansk Sintermetal, Denmark APV Pasilac A/S, Denmark tal activities with the character of Dept Corrosion and Surface Technology, long term basic research. These DTU, Denmark • projects are often done in collabora- MUP Hybrid Yarn for Thermoplastic •. A/S Kaj Neckelmann, Denmark tion with universities in Denmark, Fibre-Composites: Materials • Komposit Procesteknik ApS, Denmark and Process Technology • LM Glasfiber A/S, Denmark frequently as PhD projects. Nordtest Fractbgraphy of Cyclically • Swedish National Testing and Research Fatigued Zirconia Ceramics Institute, Sweden The activities in this area are de- • University of Tampere, Finland scribed under the subheadings Pow- JOULE-THERMIE New generation Wind • Bonus Energy A/S, Denmark ]'....' der Technological Materials and Manu- Turbine Blade .'••/•'• • Kemijqki Yo, Finland , : . facturing Technologies for Advanced • Technical Research Centre of Finland : • Garrad Hassan & Partners, Ltd., UK Fibre Composites. EUREKA New Compaction Methods Norssnk-Aalykke A/S,, Denmark for Gas-Atomized Powders Impactor Technology AB, Sweden The highlights in the area of Materi- Shockwave Metalworking Technology, als Technology are (i) the develop- The Netherlands '••:•• DTI, Denmark ment of a numerical model for simu- Swedish Institute for Prod. lation of the thermal history of at- Eng. Research / ' TNO Research Centre, The Netherlands omized particles in the spray-forming process, (ii) the development of an integrated oxygen sensor based on

Mg-SiTiO3 semiconductor, (iii) the development of a new type of hybrid yarn and associated process technologies for production of composites with thermoplastic matrix, and (iv) that the framework programme 'Hybrid Yarn for Thermoplastic Fibre Composites' under the Danish Materi- als Technology and Development Program was completed with great success and an excellent international evaluation.

36 160 Powder technology materials

This programme is concerned with the development and optimization of new powder-based materials and process technologies aiming at improved application properties, as well as testing and characterization of the materials produced.

Centre for powder-based metal matrix composites The Materials Research Department is a partner in a Danish centre for powder- based metal matrix composites (MMCs). The centre involves a number of Danish 0.00 O.05 0.10 0.15 0.20 0.25 0.30 industrial enterprises and the centre activities focus on steel-based materials Axial distance, L (m) with additions of rather cheap types of ceramics like alumina. The applications Gas and droplet axial velocities are shown as functions of the axial distance travelled from the atomizer, calculated by the numerical for the MMCs are in friction materials, model. Results are shown for droplets of 10, 20 and 40 ixm in diameter. grinding and cutting materials, and for The initial gas velocity is 150 m/s. wear purposes. The Department is particularly involved in the centre sub-project on nish industry as a new and advanced incorporates the entire history of the spray-forming of MMC materials. The production method during the next de- droplets from the formation to deposi- former gas atomizer for production of cade. A technical and scientific under- tion and cooling in the solid state. The powder has been reconstructed to allow standing of the process and of the mate- model predicts droplet velocity and also the production of spray-formed, rials properties is therefore of interest. temperature as a function of flight purely metallic bodies, and currently the It is the aim of this study to formu- distance, the extent of droplet solidifica- equipment for admixing ceramic parti- late numerical computer models for a tion on arrival at the substrate, and cles is in preparation. Special efforts quantitative simulation of dynamic and temperature distribution in the depos- were put into the development of new thermal behaviour of individual droplets ited material. The effects of process metal outlet tubes and gas nozzles. For during spray forming. The simulation parameters on droplet histories are then the outlet tube porous (approx. 30 % porosity) alumina and zirconia construc- tions were tested. The results indicate that the re-use of outlet tubes is possible 5 to 10 times. During 1997 a series of 13 % Cr steels was produced. They showed very fine microstructures in the sprayed state, in particular regarding porosity and grain size. The latter was found to be in the range from 10 to 20 ^m. The as-sprayed measured hardnesses were up to 800 Hv. The experimental activities on spray-forming are closely coordinated with the work on numerical simulation of the process.

Numerical modelling of rapid solidification processes Alumina support plate (50 mm x 50 mm) with screen printed Mg - doped SrTiO3 semiconductor and Pt-electrodes on one side Spray forming of metals is anticipated to (background) and Pt-heaters on the other side (front) for achieve commercial importance for Da- production of nine integrated oxygen sensors.

37 used for optimization of the microstruc- good reproducibility. Furthermore, a new noise filters from barium titanate-ferrite ture in droplet consolidation. The mate- type of integrated oxygen sensor was multilayer ceramics. In order to be able rials simulated are steel and copper also developed. This sensor has the to fabricate crack free filters, two main based alloys. sensor material and the electrodes on problems have to be overcome: (i) intro-

one side of an A12O3 support plate and a duction of cracks during the forming Development of ceramic Pt-heater on the other side. These inte- process (uniaxial pressing), and (ii) oxygen sensors grated sensors, which were made by delamination caused by residual stresses In an attempt to improve the properties screen-printing, showed all good adhe- originating from the rather large differ-

of Mg-doped SrTiO3 sensors, new tech- sion. Testing of the heater indicated ence in thermal expansion of the two niques were exploited for the prepara- that even the high operating tempera- materials. In the case of non-symmetric tion of starting material and sensor ture of 700 °C could be reached by a low configurations a technique was devel- fabrication. Fine and highly crystalline power consumption of the heater. Thus, oped for pressing crack free tubes and

Mg-doped SrTiO3 powder was obtained at screen printing technology proved very rectangular and disc shaped specimens. a low temperature (80 °C) by the use of attractive for sensor fabrication as it is For these samples thermally-induced a sol-precipitation process. Thus, high possible to produce sensors with repro- delamination could be avoided by using temperature calcination, generally ducible properties and a compact struc- two interlayers of intermediate composi- needed in the preparation of ceramic ture of several integrated functions. tions. powders, could be avoided. A screen- To understand the problems of ther- printing technique was used to fabricate Fabrication process for barium mally induced delamination of graded the sensors. Thanks to these new tech- titanate-ferrite functionally graded multilayers, a fracture mechanics model niques, the sensors showed good proper- ceramics was developed. The analysis showed that

ties, such as short response times to the The purpose of this project is to develop the steady state energy release rate Gss oxygen partial pressure changes and a process for fabrication of electronic is proportional to Aa2 AP E H /(1-v),

Sintered barium titanate-ferrite multilayer components for fabrication of integrated electronic noise filters. 10 mm

38 where Aa is the difference in the thermal expansion coefficients of the base materials, A7" is the temperature difference from stress-free state, H is the multilayer thickness, E and v are the Young's modulus and Poisson's ratio, respectively. For non-symmetric speci-

mens Gss was found to decrease very fast as the number of layers with intermediate properties increased. Thus, the use of interlayers may be very efficient for preventing delamination of non-symmet-

ric multilayers. In contrast, Gss was higher and decreased with a much slo- wer rate for symmetric specimens. Thus, for this configuration multilaye-ring is Inspection and evaluation of bowlshaped test specimens (240 mm i not efficient in preventing delamination. diameter) manufactured by a press consolidation technique from hybrid yarn. In front of the picture are the male and the female press tools Instead, for symmetric multilayers the and next to them a stack of fabrics is ready for processing. experimental work focuses on modifying the thermal expansion coefficients of

the base materials in order to reduce Gss by minimizing Aa.

Manufacturing of low enriched uranium fuel elements The fabrication of low enriched uranium Manufacturing technologies for (LEU) fuel elements was continued in advanced composite materials 1997. For more than 20 years all fuel elements for the research reactor DR3 at Risa have been produced in the Materi- This programme covers the development arrangement, a PC/PLC control unit, and als Research Department. The first LEU and optimization of new thermoplastic a process data sampling unit. The press elements were tested with success in the fibre composites and associated process is a single active hydraulic press with a reactor more than ten years ago. Since technologies, aiming at improved occu- maximum press force of 200 kN and a then more than 300 elements of this pational health and application proper- maximum press area of 1000 mm x 800 type have been used in the reactor. ties, as well as characterization of the mm. The material is heated under The LEU fuel elements consist of 4 produced materials. vacuum to prevent/minimize the degra- concentrically arranged tubes. Each tube dation of the thermoplastic matrix is made of 3 fuel plates welded together. Press consolidation of material prior to press forming. The Each fuel plate (1.5 mm in thickness) is thermoplastic composites into process control and data sampling sys- made as a rolled sandwich of three 3D-shapes in minutes tem regulates all process parameters: layers: a core - containing the uranium - Press consolidation of thermoplastic Process temperature, vacuum, speed of covered with Al sheets on both sides. composites is a very fast process. It is material transportation, speed of press- The core is made powder metallurgically suitable for production of smaller coming, pressure or position of the pressing from a mixture of U3Si2 and Al powder. ponents in larger series. In principle, the tool, and the pressing time. process consists of four steps: (i) Heat- Optimization of the press consolida- ing the material to the process tempera- tion technique was performed on bal- ture, (ii) transfer of the heated material anced woven fabric of glass/PET hybrid to the press, (iii) shaping, consolidating yarn. It was found to be a very robust and cooling, and (iv) removal of the process where high material quality finished part from the press. (fibre content 45 %, less than 2 % po- A new research press facility has rosity and no unwetted fibres) is ob- been designed and built. The equipment tained for a large process window. The consists of a press, a material transport press time was only 15 seconds.

39 Press consolidation of a car door-post Stress-strain curve in the transverse direction of press in thermoplastic composites consolidated unidirectional A fibre reinforced thermoplastic car glass fibre/PET laminates. door-post was produced from hybrid (Five samples on the same plot). yarn fabrics by a press consolidation technique. The door-post was made of a balanced woven fabric produced from a hybrid yarn mixed of glass fibres and PET fibres. The fabrics were stacked into a laminate with the desired thickness, heated to the process temperature (290 - 300 °C for the PET), transferred to the press mounted with a cold pressing tool, and finally pressed and consolidated into shape. Manufacturing of the door-post has with success been used to test if components with rather complex geometry Strain [%] could be produced on an industrial press line (Komposit Procesteknik). The final car door-posts were manufactured using a pressing force of 900 kN and a pressing time of only 12 seconds. The quality of the lower moisture absorption compared ing temperature was 220 - 240 °C. the material of the fabricated part was with Aramide/Epoxy composites. Composite laminates consolidated examined. The material was well consoli- form the hybrid yarn were found to have dated with a fibre content of 45 % and a Materials and mechanical excellent room temperature tensile porosity of about 2 %. properties of hybrid yarn properties. Both filament wound unidi- thermoplastic composites rectional laminates and laminates con- Light weight parabolic antenna in Two combinations of glass fibres and solidated from balanced woven fabrics thermoplastic composites polymer fibres have been developed for (Twill 3/3) were evaluated and charac- The Department's autoclave and know- the hybrid yarn. A 300 Tex glass fibre terized. All the laminates have a poros- how has been used to manufacture a roving with a special developed sizing ity lower than 1 % and a fibre content of light weight prototype parabolic an- was used in both combinations, but two 41 % and 44 %, respectively, for the tenna shell from an Aramide/PEI hybrid different types of polymer fibres, also modified PET laminates and the PET yarn. The task was commissioned by specially developed, were used for the laminates. Saab Ericsson Space AB, Sweden, and hybrid yarns. One type of polymer fibres Since the cooling rate in press con- involved autoclave process optimization was PET, and the other type was a modi- solidation is high, the crystallinity in on flat specimens, and manufacturing of fied PET with a lower melting and pro- the press consolidated PET laminates is parabolic antenna shells by the optimi- cessing temperature. The processing low, which again leads to high ductility zed autoclave consolidation technique. temperature for the hybrid yarn based of the PET matrix material. This was The driving force for using PEI as matrix on PET was 280 - 300 °C. For the modi- observed on static tensile test in the material is the electrical properties and fied PET based hybrid yarn, the process- transverse direction of unidirectional laminates, where the strain to failure was as high as 1.7 %. The high bonding strength between Unidirectional Woven fabric the fibres and the matrix material is

0 reflected by the high shear strength of •• o - direction 90°- direction Balanced Twill 3/3 the laminates, which is 50 MPa and 60 Mod. PET PET Mod. PET : PET Mod. PET PET MPa, respectively, for the modified PET

E-modulus [GPa] 32 35 8 10 20 22 and the PET matrices, measured by 12 ° off-axis tensile tests on unidirectional Tensile strength [MPa] 580 520 45 55 : 280 260 laminates. Tensile properties of composite laminates consolidated from hybrid yarn

40 Techniques

In the Materials Technology Programme a number of production facilities for advanced materials are available in addition to a series of characterization techniques. The equipment is also used by other programmes of the Department as well as in collaboration projects with external partners. In the area of Powder Technological Materials an inert gas atomizer was established a few years ago and has been reconstructed for production of spray- formed materials. In the powder mode the equipment can handle gas pressures up to 60 bar and a number of nozzle systems has been fabricated for precise Process development and optimization of autoclave consolidation for manufacturing of parabolic antenna shells. The task was commissioned control of gas/metal ratios. Furthermore, by Saab Ericson Space AB, Sweden. the melting chamber can be pressurized relative to the spraying chamber. The final powder can be further processed in sensors. In this system the electrical The facilities for fabriction of PMCs an inert gas glove box, without exposure response can be measured as a function include a high temperature autoclave to the atmosphere. of oxygen pressure, temperature and (530 °C, 20 bar, vacuum), two filament A test system is available for the time. The sensors can also be thermally winding machines (two axes) and a new evaluation of electrical properties of gas cycled. computer controlled press. The autoclave and filament winding machines are used for manufacturing of test coupons and components with both thermosetting

Method Objective and thermoplastic matrix materials. The pressing facility is combined with a pre- heating, vacuum and material transport Materials Shaping Inert gas atomizing Rapidly solidified metal powders system designed for fast processing of Spray forming Direct formation of compacted structures thermoplastic composites. from liquid particles

Inert gas glove box Handling of reactive materials

Uniaxial powder pressing Green bodies

Rolling Deformation

Heat treatments Sintering (ceramic and metal parts)

Filament winding Continuous fibre composites (test specimens and: components)

Autoclave technique Consolidation or cure of PMCs

Press consolidation Consolidation,of PMC composites

Characterization BET Surface area.of powders Techniques Thermal analysis Thermal response (expansion/weight/ heat evolution)

Sensor testing Electrical properties, long term stability

Microscopy Fibre distribution and orientation, evaluation of. materials

Matrix digestion Fibre and porosity content in composites

41 FINANCES 1997

The activities of the Department are supported by a combination of direct Government funding, focused project Income 1997 DKK 1000 US$ 1000 funds from national, international and EU programmes and fully commercial Direct funding / industrial contracts. (Ministry of Research and Technology) 12 893 1862 The numbers given in the tables are in units of 1000 Danish Kroner (DKK). Project funding :: 35 681 5 153

" -. - '•:'••"'' '' ! •'• The equivalent amount in US Dollars is also shown (DKK 1000 equal US$ 144, 48 574 7 015 alternatively, 1 US$ equals 6.92 DKK). The decrease in direct funding from Expenditure 1997 1996 to 1997 is due to the fact that payment of electricity and heating was Salaries 33 547 4 845 removed from the budget of the Depart- : ment. Operating expenses 11964 , 1 728 The difference between Income and Equipment 2 112 305 Expenditure for 1997 turned out to be 951,000 DKK (138,000 US$) i.e. less Total 47 623 6 877 than in 1996, but still satisfactory.

PersonelLe

H Academic staff Income 1993 - 97 (DKK millions, 1997 kroner)

H Tecnical staff H Project founding H Post graduate students and post docs H Direct founding •i Guest scientists 50 r 50 ~

40 40

20 h ll ll 10 I I I 1993 1994 1995 1996 1997 1993 1994 1995 1996 1997 Research areas Manpower

Materials Technology Direct funding

Materials Science

Project funding Materials Engineering Administration

DR3 fuel elements

Materials Chemestry

Project income • International projects • National projects

Symposiums etc. Energy research program Industrial projects (EFP)

Miscellaneous

Materials technology programme (MUP) BRITE-EURAM JOULE, EU-Fusion

Engineering Science Centre

43 PERSONNEL 1997

In 1997 18 members of the Department Eldrup, Morten Postgraduate students left and 15 new members joined (*) the Gundtoft, Hans Erik Carstensen, Jesper Vejlø Department Hendriksen, Peter V. Clausen, Bjørn until 31 May Horsewell, Andy Hansen, Jesper Rømer* Johansen, Bjørn S. Larsen, Dorte Jørgensen, Mette Juhl Head of Department Mullit, Paw M. Juul Jensen, Dorte Niels Hansen Nielsen, Steen Arnfred Jørgensen, Ole until 31 Jan. Nielsen, Søren Fæster* Kindl, Bruno Petersen, Kenneth" Knudsen, Per until 31 Jul. Pryds, Nini H. until I Mar. Scientific staff Koch, Anita H.* Rasmussen, Torben Larsen, Peter Halvor Adolph, Eivind Sbrby, Lennart Leffers, Torben Andersen, Svend Ib Thorsen, Peter A. until 15 Aug. Appel, Charlotte C. Lilholt, Hans Bagger, Carsten Linderoth, Søren Bentzen, Janet J. Liu, Qing Bilde-Sørensen, Jørgen B. Liu, Yi Lin Post docs Bonanos, Nicholaos Lorentzen, Torben Ahlgren, Erik until 31 Jul. Borring, Jan Lystrup, Aage S. Armstrong, William D. until 24 Jun. Borum, Kaj K. Løgstrup Andersen, Tom Christoffersen, Henrik until 31 May Brøndsted, Povl Mogensen, Mogens Dam, Niels Ebbe* Christensen, Jørgen until 31 Jan. Nilsson, Tage M. Garbe, Stephan until 1 Oct. Debel, Christian P. Pedersen, Allan Schrøder Holtappels, Peter W.' Pedersen, Ole Bøcker Huang, Xiaoxu Poulsen, Finn Willy Jacobsen, Torben, K." Poulsen, Henning F. Krieger Lassen, Niels C. Primdahl, Søren Lyttle, Mark' Rheinländer, Jørgen Kindermann, Lutz until 30 Nov. Singh, Bachu N. Laffarague, Denis* Sørensen, Bent F. Lienert, Ulrich Sørensen, Ole Toft Marina, Olga A. Toft, Palle Mishin, Oleg V.* Toftegaard, Helmuth L. Pantleon, Wolfgang* Winther, Grethe* Pryds, Nini H.* Sarroute, Sabine until 31 Dec. Schiøtz, Jacob* Thomsen, Niels, B.@ until 31 Oct. Thorsen, Peter A.*

® Industrial Post Doc, Danfoss/Risø

44 Consultant Olsen, Ole Apprentices Olsson, Jens 0. Waagepetersen, Gaston Christensen, Lars F. Paulsen, Henrik Fabritius, Nicolai Porsdal, Helle until 31 Jan. Hammershøj Olsen, Casper Pedersen, Niels Jørgen Klein, Roland Technical staff Robl, Steen until 31 Aug. Nilsson, Jesper Adrian, Frank Sandsted, Kjeld Borchsenius, Jens F.S. Schmidt, Jesper* Dreves Nielsen, Poul Strauss, Torben R. Frederiksen, Henning Sørensen, Erling Gravesen, Niels Nørregaard Aagesen, Sven Hersbøll, Bent Jensen, Finn E. until 31 Jul Jensen, Knud Office staff Jensen, Palle V. Dreves Nielsen, Elsa Jespersen, John Kjær, Anne-Mette Heie Hoffmann Nielsen, Lis Kjøller, John Kristiansen, Lisbeth Aa until 10 Jun. Klitholm, Cliver Lauritsen, Grethe Wengel Larsen, Bent Mortensen, Jytte Larsen, Birgit N. Sørensen, Eva M. Larsen, Jan Thomsen, Ann Larsen, Kjeld J. C. Voss, Anita Lillegaard, Keld Lindbo, Jørgen Mikkelsen, Claus Nielsen, Birgitte Nielsen, Palle H. Nilsson, Helmer Olesen, Preben B. Olsen, Benny F. Olsen, Henning

45 COMMUNITY ACTIVITIES

deformation at constant plastic strain amplitude. Steen Arnfred Nielsen Postgraduate (PhD) projects Dislocation microstructures and surface damage Ultrasonic characterization of materials using evolution are characterized by TEM, SEM and tomographical methods'. Many PhD projects are conducted at the Materi- optical microscopy. This project focuses on ultrasonic characteriza- als Research Department in collaboration with The Technical University of Denmark, Lyngby. tion of polymer materials using computer universities in Denmark and other countries. Supervisor: Ole Becker Pedersen tomography. The main goal is the investigation of image reconstruction techniques based on Jesper Renter Hansen fan-beam projections. Examination with ultra- 'Structural and electrical properties of electron sonic through-transmission scanning equipment PhD Projects finished during 1997 conducting perovskites'. is used to verify the applicability of fan-beams Materials such as La^^yyyMby30 3 s with Mb=V, for non-destructive applications, in particular Sn, Ti, Zr may be used as interconnect for solid the study of defects. Bjorn Clausen oxide fuel cells. The materials exhibit expansion The Technical University of Denmark, Lyngby. 'Characterization of polycrystal deformation by on reduction. In this project the nature of this Supervisors: Hans Erik Gundtoft, Svend Ib numerical predictions and neutron diffraction expansion is investigated with the aim of Andersen, Jorgen Eheinlander experiments'. finding means to minimize the effect. The Technical University of Denmark, Lyngby. The Technical University of Denmark, Lyngby. Soren Faster Nielsen Supervisor: Torben Lorentzen Supervisor: Mogens Mogensen, Finn W. Poulsen, 'Organized structures in deformed aluminium'. Peter V. Hendriksen The dislocation structure in compressed alu- Torben K. Jakobsen minium is studied by synchrotron radiation and Influence of holes and notches on the fatigue Ninette Kjerulf-Jensen electron microscopy. The main goal is to make behaviour of 2-D woven ceramic matrix compos- 'Raman and IR-spectroscopic investigation of in-situ studies of the evolution of the dislocation ites'. SOFC materials'. structure and the crystallographic orientations The Technical University of Denmark, Lyngby. Solid oxide fuel cell materials will be character- when the sample is compressed. Supervisor: Povl Bmndsted ized individually and in fuel cells under operat- University of Copenhagen, Denmark. ing conditions by vibrational spectroscopy and Supervisor: Torben Leffers Nini H. Pryds other suitable spectroscopic methods. Correla- •Rapid solidification of stainless steel'. tions with structure and defect chemistry will be Kenneth Petersen The Technical University of Denmark, Lyngby. made. 'Development of the spray-forming process for Supervisor: Allan Schwder Pedersen The Technical University of Denmark, Lyngby. production of steel-based composites'. Supervisor: Finn Willy Poulsen The aim of the project is to identify the correla- Torben Rasmussen tion of the applied, experimental parameters and 'Structure and dynamics of dislocations'. Darja Kek the properties of the resulting material. This is The Technical University of Denmark, Lyngby. 'Electrochemical properties of interfaces between done by studying the effect of parameter varia- Supervisors: Torben Leffers, Ole Becker Pedersen metals and solid state ion conductors'. tions and by investigation of the alloy solidifica- The interfaces between ceramic ionic conductors tion in the presence of ceramic particles and the Chris Pickup (SrCeO -based proton conductor and YSZ oxide final microstructures. The project focuses on 'A study of the annealing and mechanical 3 ion conductor) and metals (Ni, Ag, Au, Pt) are wear properties, strength and toughness. behaviour of electrodeposited Cu-Ni multilayers'. studied at various temperatures using impedance The Technical University of Denmark, Lyngby. University of Cambridge, UK. spectroscopy. Also the electrode kinetics in Supervisor: Allan Schwder Pedersen Supervisor: Andy Horsewell hydrogen at low partial pressure are investigated. Peter A. Thorsen National Institute of Chemistry/University of 'The influence of the grain boundary structure Ljubljana, Slovenia. on diffusional creep'. Supervisor: Mogens Mogensen The University of Copenhagen, Denmark. Supervisor: Oergen B. Bilde-Serensen Dorthe Larsen 'Structural and electrical properties of perovskites'. Oxides with perovskite structures such as LaAlO3, Ongoing PhD Projects LaGaO3 and LaScO3 doped with SrO and MgO are studied. The main purpose of the study is to find Michael S. Brown relationships between the detailed crystal struc- 'Anodes for solid oxide fuel cells'. tures and the conductivities of the materials. Technological types of Ni-YSZ-cermet anodes are The Technical University of Denmark, Lyngby. studied, in particular features like the correla- Supervisors: Mogens Mogensen, Finn W. Poulsen tions between the performance and Ni/YSZ-ratio, particle size of Ni and YSZ, porosity and elec- Paw Mullit trode thickness. 'Quantification of the pore structure in porous University of Waikato, Hamilton, New Zealand. materials'. Supervisor: Mogens Mogensen The mechanical and physical behaviour of porous materials, such as cement, concrete and brick, is Jesper Vejlo Carstensen strongly influenced by the shape, size and 'Structure development and mechanisms in amount of pores in the material. Although fatigue of polycrystalline brass'. understood qualitatively, quantitative treat- The influence of stacking fault energy on fatigue ments of the relationship between pore stereolo- is studied with polycrystalline brass as a model gy and properties need to be developed. system. Specimens of Cu with 15 % Zn and Cu The Technical University of Denmark, Lyngby. with 30 % Zn with well-characterized grain size Supervisor: Andy Horsewell distribution and texture are subject to cyclic

46 Svend Ib Andersen Undergraduate projects Jorgen B. Bilde-Sorensen Lennart Sorby Torben Lorentzen 'Structural study of SOFC materials'. Jesper Ramer Hansen Allan Schredei Pedeisen Diffraction techniques based on X-ray, neutron 'Conducting perovskites: Investigation of Bent F. Sorensen and synchrotron radiation are used to study KAA»V« structure, conductivity and Ole Toft Sorensen solid oxide fuel cell materials, both under oxygen diffusion'. The Technical University of Introduction to new materials'. The University of equilibrium and dynamic conditions. Structure : Denmark, Lyngby. Aarhus, Denmark. (Distance learning) refinement is done by the Rietveld method. Supervisor: Mogens Mogensen, Finn W. Poulsen, University of Uppsala, Sweden.. Peter V. Hendriksen Supervisor: Finn Willy Poulsen External Examiners Michael Nielsen Bent Tveten 'Classification of a filmless radiogiaphic system'. Svend Ib Andersen 'High temperature oxidation of metals'.: The Engineering College of Copenhagen, Studies of the kinetics of formation and nature Jorgen B. Bilde-Sarensen Ballerup, Denmark. Christian P. Debel of the oxidation products on Cr-Fe alloys in Supervisor: J0rgen Rheinlander moist air up to 1000 °C are carried out. Thermo- Morten Eldrup gravimetry, electron microscopy and X-ray Andy Horsewell Jacob Olsson Hans Lilholt diffraction are used as major tools of characteri- 'Measurement of vein thickness in digitized zation. Finn Willy Poulsen radiographs of rabbits (drug testing)'. Ole Toft Sorensen The University of Oslo, Norway. The Engineering College of Copenhagen, Supervisors: Mogens Mogensen, Finn Willy Members of the officially appointed corps of Balleiup, Denmark. Danish university examiners (MSc and BSc). Poulsen Supervisor: J0rgen Rheinlander Rolf Jarte Aberg Svend Ib Andersen Andrew J. Perry PhD examiner. University of Aalborg, Denmark. 'Studies of kinetics and reaction mechanisms on Investigation into semiconducting oxygen Ni-YSZ anodes for solid oxide fuel cells (SOFC)'. sensors based on Mg doped strontium titanate'. Ni-YSZ cermets are used as anodes for oxidation Povl Brondsted University of Bath, UK. PhD examiner. Technical University of Denmark, of hydrogen and CO in SOFC. Several rate limiting Supervisor: Ole Toft S0rensen steps in the electrode mechanism have been Lyngby. suggested. Experiments with Ni-electrodes with David Coimbra Christian C. Debel well defined geometry are used to elucidate the 'Nemst-type oxygen sensors: synthesis and mechanisms. : BSc examiner. Engineering College of Copenha- characterization of gen, Ballerup, Denmark. Norwegian University of Technology and Science, samaria/praseodymia doped ceria and testing of Trondheim, Norway. yttria-stabilized zirconia sensors'. Supervisor: Mogens Mogensen : Peter V. Hendriksen Ecole Nationale Superieure de Ceramique PhD examiner. Norwegian University of Technol- Industrielle, Limoges, France. ogy and Science, Trondheim, Norway. Supervisor: Ole Toft Serensen Hans Lilholt PhD examiner. University of Aalborg, Denmark.

Allan Schroder Pedersen External lecturers and PhD examiner. University of Copenhagen, examiners Denmark Ole Toft Sorensen Many of the staff members of the Materials PhD examiner. The Technical University of Research Department are actively involved in Denmark, Lyngby. education and training in materials science as university external lecturers and examiners.

External lecture courses Staff members on

Charlotte C. Appel assignment abroad Jorgen B. Bilde-Sarensen Andy HorseweYl Charlotte C. Appel 'Electron microscopy and microanalysis'. Course Statoil R&D Centre, Trondheim, Norway. 5 -12 no. 10455. The Technical University of Denmark, Danuary. Lyngby. Nikolaos Bonanos Ole Toft Serensen National Technical University of Athens, Greece. 'Defect chemistry'. Course no. 3525. The Techni- 7 - 25 April. cal University of Denmark, Lyngby. Niels-Ebbe Dam MogensMogensen Carnegie Mellon University, Pittsburgh, PA, USA, 'Oxygen ion and mixed conductors and their 20 October - 1 December. technological applications'. 33rd Course. NATO Advanced Study Institute: International School Mette Juhl Jorgensen of Materials Science and Technology. Erice, Sicily, Birchall Centre for Inorganic Chemistry and Italy. Materials Science, Keele University, Staffordshire, UK. 13 - 22 February.

47 Torben Leffers National University of Rosario, Argentina. 3-15 November. Roadshow The Engineering Science Centre has applied the concept of 'Roadshow' to Jergen Lindbo Sandia National Laboratories, Livermore, CA, materials research: a number of staff members from the Department turn up USA. 1 - 22 March. at an industrial company and present lectures about the activities within the centre. The lectures are selected by the company from a long list (at Falle Nielsen School of Mines, St. Etienne, France. 9 - 19 present comprising 32 titles). Several shows have been organized in 1997. September. The two largest were at Danfoss A/S (70 industrial participants, 8 from the Department) and at Grundfos A/S (about 30 industrial participants, 4 from Bachu N. Singh AEA Technology. Harwell, UK. 21 - 25 April. the Department). Roadshows have also been held at Dronningborg Indus- tries A/S, Elektro-Isola A/S, Adtranz Danmark A/S, and TIC Roskilde Amt/ Ole loft Sorensen Ingemann Maskinfabrik by one lecturer from the Department and about 10 University of Science and Technology of China, Hefei, China. 29 September - 12 October. industrial participants each time. Xi'dian University, Xian, China. 13 - 20 October.

Visiting scientists at the Materials Research Department

Dr. Dan J. Edwards Many guests visited or worked in the Depart- Dr. Alberto Borrego Pacific Northwest National Laboratory, Richland, ment during 1997. CENIM, Madrid, Spain. 7 August -12 October. WA, USA. 15 November - 14 December. Dr. Nina Aas Michael S. Brown Chen Fanglin Statoil R&D Centre, Trondheim, Norway. 3 - 6 University of Waikato, Hamilton, New Zealand. University of Science and Technology of China, November. June - 9 December. Hefei, China. 15 January -15 April. Prof. Brent Adams Gabriele Bruckner Dr. Stanislav I. Golubov Carnegie Mellon University, Pittsburgh, PA, USA. RWTH Aachen, Germany. 11-24 August. Institute of Physics and Power Engineering, 16 June - 10 July. Obninsk, Russia. 1-16 April, 1 August - 30 David Coimbra September. Dr. V. S. Ananthan Ecole Nationale Superieure de Ceramique 17 May - 17 October. Industrielle, Limoges, France. 3 March - 31 December. Dr. Tetsuya Hirade Chalmers University of Technology, Gothenburg, Dr. Claire Y. Barlow Sweden. 10-12 April, 15-26 September, 9 - 22 University of Cambridge, UK. 22 August - 5 Prof. Julian Driver November. September. School of Mines, St. Etienne, France. 7-20 September. Michael Hanke Technical University, Braunschweig, Germany. 7 - 14 September.

Dr. Howard L. Heinisch Pacific Northwest National Laboratory, Richland, WA, USA. 29 June - 11 July.

Malte Hollmann Technical University, Dresden, Germany. 22 - 27 November.

Prof. John W. Holmes University of Michigan, Ann Arbor, MI, USA. 2 - 6 April.

Dr. Darcy Hughes Sandia National Laboratory, Livermore, CA, USA. 28 July - 24 August.

Byoung-Sam Kang Korea Electric Power Research Institute, Taejan, Korea. 3-28 November.

Darja Kek National Institute of Chemistry, Ljubljana, Slovenia. 1 February - 31 July, 15 September - 19 December.

48 Jens Keueileber Prof. Francis W. Zok Prof. Meng Guangyao Freiberg University of Mining and Technology, University of California, Berkeley, USA. 30 April - University of Science and Technology of China, Germany. 2 - 10 December. 4 May. Hefei, Anhui, China. 'Applications and preparation of ceramic mem- Dr. Volker Klemm Rolf Jarle Aberg branes'. Freiberg University of Mining and Technology, Norwegian University of Technology and Science, 11 July. Germany. 2-6 December. Trondheim, Norway. 8 - 20 September. Prof. Ramesh Talreja Anne Kontges Georgia Institute of Technology, Atlanta, GA, RWTH Aachen, Germany. 11 - 24 August. USA. 'Recent studies in damage mechanics of compos- Prof. Amar N. Kumar Colloquia ite materials'. Indian Institute of Technology, New Delhi, India. 14 August. 1-31 January. Dr. Hiroshi Takagi Murata Company, Kyoto, Japan. Dr. Laurence Mott Carrie B. Manon 'Status of the SOFC programme at Murata Co.' Bio Composites Centre, Bangor, UK. Alfred University, New York, NY, USA. 1 - 31 23 January. 'Testing of plant fibres and microtomography of January. fibres and composites'. Prof. John W. Holmes 21 October. Rozlyn Phillips The University of Michigan, Ann Arbor, MI, USA. University of Waikato, Hamilton, New Zealand. 1 'Fatigue behaviour of ceramic matrix composites'. Malte Hollmann May - 28 August. 4 April. Technical University, Dresden, Germany. 'Cyclic plasticity of nickel single crystals charac- Robin Preston Prof. Erik Johnson terized at different temperatures and different Cambridge University, OK. 19 - 27 May. University of Copenhagen, Denmark. length scales'. "TEM studies of nanosized inclusions in alu- 25 November. Prof. Brian Ralph minium'. Brunei University, London, UK. 26 - 31 July. 6 May. Prof. Amiya K. Mukherjee University of California, Berkeley, CA, USA. Jaydeep Sarkar Prof. Brent L. Adams 'New results on nanometals, nanointermetallics Cambridge University, UK. 19 - 27 May. Carnegie Mellon University, Pittsburgh, FA, USA. and nanoceramics: Processing and some me- 'A mesoscale study of the interaction of grain chanical properties'. Prof. Ramesh Talreja boundaries with the deformation field'. 8 December. Georgia Institute of Technology, Atlanta, GA, 8 July. USA. 4 -15 August.

Prof. John Wert University of Virginia, Charlottesville, VA, USA. 5 June -16 July. Prof. Kjell Wiik Distance learning using video conferencing The Norwegian University of Science and Tech- nology, Trondheim, Norway. 4 August - 17 As described in other sections, the staff of the Department has become December. increasingly involved in educational activities, for example by teaching undergraduate and PhD-students both through lecture courses and project Dr. Erik Woldt Technical University, Braunschweig, Germany. 1 - work. To further increase the possibilities for interaction with the university 26 September. world and its students and to promote the communication with industrial partners, a video conferencing system was installed at the end of 1996 in a Hong Zheng University of Science and Technology of China, dedicated room in the Department. The facility was established in collabora- Hefei, China. 1 January - 31 December. tion with all the major universities in Denmark who also acquired similar facilities. The aim is that lecture courses given at one institution can be followed by students at other universities by two- or multi-way video links, i.e. using the so-called distance learning principle. Similarly, meetings can be arranged between participants at different locations, so-called video conferences. In all cases travel money and time are saved. After the official opening in May by the Minister of Education of the eight collaborating Video Conferencing Centres a distance learning course. Introduction to New Materials', from Ris0 to Aarhus University has been carried out, as well as a number of meetings with Danish and foreign participants to discuss research collaboration and planning of education.

49 Dorte Juul Jensen Jorgen B. Bilde-Sarensen The Advisory Committee for the Engineering Editorial Board of 'Microscopy Research and Science Centre (at Ris0) for Structural Charac- Technigues'. terization and Modelling of Materials. Member of the board of the Scandinavian Society Board of the Danish Research Councils. [Chair- for Electron Microscopy. man). Nikolaos Bonanos Peter Halvor Laisen International Advisory Board on International Danish Ceramic Society. (Chairman from 19 Conferences on Solid State Protonic Conductors. November). Povl Brondsted Torben Leffers Editorial Board of 'Advanced Composites Letters'. Working Group for the Formulation of a National Strategy for Materials under the Ministry of Morten Eldrup Research. International Advisory Committee on Interna- tional Conferences on Positron Annihilation. The Chemistry and Materials Commission of the Danish Technical Research Council. (Until June International Programme Committee for the 11th 30). International Conference on Positron Annihila- tion. May 1997. Kansas City, MO, USA. The Coordination Committee for the Danish Materials Technology Development Programme. Advisory Board of 'Materials Science Forum'. Copenhagen. (Chairman). Niels Hansen Task Force for the EU Programme on Standards, The COST 501 Management Committee on Measurements and Testing. Copenhagen. Materials for Energy Conversion Using Fossil Participation in Fuels. Brussels, Belgium. The Board of Ingeniarvidenskabelig Fond og G. committees A. Hagemanns Mindefond. The COST Technical Committee on Materials. Brussels, Belgium. Danish committees Aage Lystrup The Steering Committee for the Danish Solar Cell The Fusion Technology Steering Committee Hybrid Car project. (FTSC-I). Brussels, Belgium. Eivind Adolph Technical Assessor, DANAK. Copenhagen. Mogens Mogensen Technical Scientific Advisory Board, GKSS The Steering Committee of the Danish Solid Forschungszentrum. Geesthacht, Germany. Carsten Bagger Oxide Fuel Cell Programme. The Steering Committee for the Danish Solid Editorial Board of 'Revue de Metallurgies Oxide Fuel Cell Programme. Contributor to 'The Great Danish Encyclopedia' (in Danish 'Den Store Danske Encyklopaedi'). Editorial Board of 'Monographs in Materials The Steering Comittee for the Danish Supercon- Copenhagen. Science'. ductor Programme. Jens Olsson Dorte Juul Jensen The Steering Committee for the MUP 2.2 Pro- The Board of Governors of Rise National Labora- Advisory board of 'Zeitschrift fur Metallkunde'. gramme: Electroceramic Functionally Graded tory. Roskilde. (Staff representative). Materials. International Committee for the International Ole Becker Pedersen Conferences on the Strength of Materials Janet J. Bentzen Contributor to The Great Danish Encyclopedia' (ICSMA). The Executive Committee of the Danish Society (in Danish 'Den Store Danske Encyklopsdi'). for Materials Research and Testing. Copenhagen. International Committee for the International Conference on The Quantitative Description of Povl Btandsted Spren Primdahl Materials Microstruture (Q-MAT). April 1997. The Executive Committee of the Danish Metallur- The Executive Committee of the Danish Electro- Warsaw, Poland. gical Society. (Chairman). chemical Society. (Chairman). Peter Halvor Larsen Niels Hansen Bent F. Sorensen Nordic Society for Thermal Analysis and The Danish Ministry of Environment and Energy, The Executive Committee of the Danish Ceramic Calorimetry. Advisory Group for Advanced Energy Technolo- Society. gies. Copenhagen. Organizing Committee of the 12th International Ole loft Sorensen Conference on Thermal Analysis and Calorimetry. Technical Assessor, DANAK. Copenhagen. Danish Ceramic Society. (Chairman, until 19 August 2000. Copenhagen, Denmark. November). Reference Group for the BRITE/EURAM Pro- Torben Leffers gramme, The Danish Ministry of Industry. Editorial board of 'Textures and Microstructures'. Copenhagen. International committees International Advisory Committee for the The Steering Committee for the Danish Solid International Conference on Texture and Oxide Fuel Cell Programme. Ris0. Svend Ib Andersen Anisotropy of Polycrystals. September 1997. Clausthal, Germany. The Advisory Committee for the Engineering The European Structural Integrity Society. Delft, The Netherlands. Science Centre (at Rise) for Structural Charac- Hans Lilholt terization and Modelling of Materials. Editorial Board of 'Journal of Strain Analysis'. Project Management Committee of the EU BRITE Project: 'Thixoforming of Advanced Light Metals for Automotive Components (TALMAC)'. (Chair- man).

50 Symposia and workshops

18th Riso Symposium The 18th Ris0 Interna- tional Symposium on Materials Science for 1997 was entitled: 'Polymeric Composites - Expanding the Limits', and took place in the great lecture hall at Ris0 on 1 - 5 September 1997. The Symposium had 83 participants from industry, research institutes and universities, representing 15 countries, including a strong representation from Danish industry; special funding support from the Nordic Academy for Advanced Study (NorFa) enabled 7 re- searchers from the Baltic •: :;W:•.••;'> states to participate. • • Composite materials are becoming an increasingly ing and interfacial aspects were presented, and empha- important part of the spectrum of materials available; sized the need to produce high quality composites and for the design and manufacturing of products and com- related components so that the industry can use them ponents. This situation is of special importance in the with confidence. energy, transport and environmental industries. In this The symposium was organized by" the Materials field of materials engineering the polymeric composites Research Department, in collaboration with the Engi- are the most developed and most successfully used neering Science Centre for Structural Characterization materials within the composites group. . • ?" and Modelling of Materials and with the Danish Materi- There is continuing scope for expanding the limits, als Technology Development Programme (MUP-2-frame- both in terms of materials constituents and properties work programme). Composite materials have been the and in terms of component design and manufacturing. theme of previous Ris0 Symposia in 1982,1988 and Materials science forms the basis for designing of com- 1991, where polymeric, metallic and ceramic composites ponents, ranging from small functional devices, to large were covered. load bearing structures. :^ S^ : Organizers: Svend Ib Andersen, Povl Brondsted, Niels The theme of the symposium was covered by the 15 Hansen, Ole Jergensen, Grethe W. Lauritsen, Hans invited review papers and 43 contributed papers ad- Lilholt, Aage Lystrup, Bent F. Serensen, Helmuth dressing materials, properties and applications within Toftegaard polymeric composites. The approach was that of consid- ering the topics in context, with focus on new aspects Nordic Ceramics' 97 which were likely to expand the limit for the engineer- The annual Nordic Ceramics meeting was arranged to- ing applications of polymeric composites. The subjects gether with the ceramic societies in Denmark, Norway concerned further developments in established fields; and Sweden at the Ris0 National Laboratory during 26 - such as cracks and fatigue as well as design and non- 27 May 1997. This symposium attracted 90 participants destructive evaluation. The subjects also addressed new especially from the Nordic Countries. 10 invited lectures developments, such as polymeric fibres and plant fibre and 26 contributions were presented at this symposium. composites, as well as elastically isotropic composites Organizers: Torben R. Strauss, Bent F. Sarensen, Ole and shape active composites. Furthermore, manufactur- Toft Sorensen, Anita Voss

51 Scientific Programme Committee of the 10th International Conference on Mechanics of Composite Materials (MCM). April 1998. Riga, Latvia.

International Advisory Committee for the International Meeting on Composite Materials: 'Advancing with Composites '97'. May 1997. Milan, Italy.

International Advisory Committee for the Second International Symposium on Engineering Ceram- ics and Third International Symposium on High Temperature Ceramic Matrix Composites. Septem- ber 1998. Osaka, Japan.

International Advisory Board for the Second International Conference on Composites and Ceramics. May 1998. Moscow, Russia.

International Advisory Committee for the 4th International Conference on Deformation and Fracture of Composites. March 1997. Manchester, UK.

International Advisory Committee for the Topical Symposium V: 'Advanced Structural Fibre Com- posites' of World Forum on New Materials. June Teaching of high school students 1998. Florence, Italy. Programme Committee for the Dedicated Confer- - an investment in the future ence on Materials for Energy-Efficient Vehicles, (International Symposium on Automotive In recent years Danish students have shown less interest in Technology and Automation, ISATA). June 1998. education within the scientific fields. This is a disturbing Florence, Italy. development in our modern society which depends on a work Executive Committee for the 8th European force possessing a high standard of scientific and technical Conference on Composite Materials. (ECCM-8). skills. Thus, there is a great need to stimulate the interest of June 1998. Naples, Italy.

young people in scientific subjects. As a part of Riso's efforts International Committee for Composite Materi- in this respect, the Department is running a one day course als. Philadelphia, USA. for high school students. The course covers theory and prac- European Association for Composite Materials, tice within the field of materials science, specifically polymer Standing Committee. chemistry and polymer based fibre composites. This provides the students with some knowledge about the production and Editorial Board of 'Advanced Composite Materi- the properties of materials along with the experience that als'. science can be exciting. The course has been developed as a Editorial Board of 'Composite Science and joint venture between the Materials Research Department, Technology1. the Condensed Matter Physics and Chemistry Department and Editorial Board of 'Polymers and Polymer Com- teachers at Himmelev Gymnasium. As background material, posites'. the book 'On polymeric materials' (in Danish) by J.S. Petersen and L Schulz, Himmelev Gymnasium, has been Editorial Board of 'Applied Composite Materials'. written and published. In 1997, three classes (47 students) Soren Linderoth have participated in the course and the feedback from stu- Advisory Board of 'Diffusion and Defect Data'. dents and teachers has been very positive. The Project Management Committee of the EU The Department also supervises individual projects for a BRITE-EURAM project 'Low-cost Fabrication and limited number of high school students. One such project was Improved Performance of Solid Oxide Fuel Cell Stack Components'. carried out in 1997: Torben Lorentzen Jakob Hessel Andersen VAMAS committee, Technical Working Area TWA20, Measurement of Residual Stresses. 'Environmental scanning electron microscopy'. Roskilde High School (in Danish 'Amtsgymnasiet'), Roskilde, Editorial board of 'Journal of Neutron Research'. Denmark. Mogens Mogensen Supervisor: Jorgen B. Bilde-S0rensen The Project Management Committee of the EU JOULE 3 project Improving Durability of Solid Oxide Fuel Cell Stacks'. (Chairman).

52 The Project Management Committee of the EU Finn Willy Poulsen Organizing Committee for the International BPJTE-EURAM project 'Low-cost Fabrication and Expert and Danish contact IEA Annex SOFC Workshop on Basic Aspects of Differences in Improved Performance of Solid Oxide Fuel Cell collaboration. Irradiation Effects Between FCC, BCC and HCP Stack Components'. (Chairman). Metals and Alloys. October 1998. Santillana del The Fuel Cell Committee under the Nordic Energy Mar, Spain. The Organizing Committee of the 'Third Interna- Research Programme. As, Norway. tional Symposium on Ionic and Mixed Conduct- Bent F. Sorensen ing Ceramics', part of 'Joint International Organizing Committee for the Third European Editorial Board of 'Key Engineering Materials'. Meeting - ECS and ISE'. September 1997. Paris, Solid Oxide Fuel Cell Forum. June 1998. Nantes, France. France. Ole Toft Sorensen Nordic Society for Thermal Analysis and Calori- The Executive Committee of the High Tempera- Bachu N. Singh metry. ture Materials Division of the Electrochemical Expert Group on Structural Materials, EU Fusion Society. Pennington, NJ, USA. Technology Programme. Brussels, Belgium. ICTAC Standardization Committee.

The Nomination Commitee for the Outstanding Task Force Materials, EU Fusion Technology Organizing Committee of the 12th International Achievement Award of the High Temperature Programme. Brussels, Belgium. Conference on Thermal Analysis and Calorimetry. Materials Division of the Electrochemical Society. August 2000. Copenhagen. (Chairman). Pennington, NJ, USA. International Organizing Committee for the 8th International Conference on Fusion Reactor Editorial Board of 'Journal of Thermal Analysis'. Wolfgang Pantleon Materials. October 1997. Sendai, Japan. Working Group 'Computer Simulation - Modelling Committee for the election of Professor in in Materials Science' of the German Society for Organizing Committee for 19th International inorganic chemistry at Norwegian Technical- Materials Science. (Vice-Chairman). ASTM Symposium on the Effect of Radiation on Natural Science University, Trondheim, Norway. Materials. June 1998. Seattle, WA, USA. Ole Becker Pedersen Scientific Committee for the International Conference on Fatigue of Composites. June 1997. Paris, France.

Social activities

The Materials Research Department's social committee, MAK, keeps track of special birthdays, anniversaries, weddings etc. MAK is also responsible for the traditional Christmas party and a summer picnic. In 1997 the summer picnic consisted of a fondue party in Copenhagen and included a visit to the Tycho Brahe Planetarium. The Christmas party was held at Riso. Members of the Department are very active in organization of ath- letic activities throughout Rise. The badminton club, for example, plays two hours every Monday evening in a nearby hall and holds two annual tournaments in a relaxed atmosphere. The winners are given small prizes accompanied by teasing praise at a celbratory dinner. Jogging is another favourite sport of the Department. A team of relay runners from the Department was the second best team from Ris0 in a major fitness arrangement in Copenhagen and members from the Department also did well in the prestigious annual 'Riso competition'. The Department is also strongly represented in the less physical activities, e.g. the Riso art society which sponsors regular exhibitions in the foyer of the Ris0 canteen and lends pictures to members' offices and to departments. Department staff are also active in 'Culture at work', a Ris0 organization which arranges visits to the theatre, museums and other cultural events. These departmental social activities promote interactions between the regular staff and the increasing numbers of new graduate students, post docs and visiting scientists, many of them from abroad.

53 PUBLISHED WORK

International publications 14. Cai, S.; Millar, C.E.; Pedersen, L; Toft S0ren- 24. Daveau, S.; Brandon, N.P.; Bonanos, K, Elec- sen, 0.; Xu, Y., Extrusion and properties of lead trical conduction phenomena in coked industrial zirconate titanate piezoelectric ceramics. Ferro- reforming catalysts. Mater. Res. Bull. (1997) v. electrics (1997) v. 196 p. 389-392 32 p. 205-212 1. Ahlgren, E.O., Thermoelectric power of SrCe0g5Y0503,. Solid State Ionics (1997) v. 97 p. 15. Carstensen, 3.V.; Pedersen, O.B., Texture and 25. Daymond, M.R.; Bourke, M.A.M.; von Dreele, 489-495 grain-size effects on cyclic plasticity in copper R.; Clausen, B.; Lorentzen, Z, Use of Rietveld and copper-zinc. Mater. Sci. Eng. A (1997) v. refinement for elastic macrostrain determination 2. Ahlgren, E. 0., Thermoelectric power of Gd- 234/236 p. 497-500 and for the evaluation of plastic strain history doped barium cerate. J. Phys. Chem. Solids from diffraction spectra. 3. Appl. Phys. (1997) v. (1997) v. 58 p. 1475-1480 16. Chen F.L.; Toft Sorensen, 0.; Meng, G.Y.; 82 p. 1554-1562

Peng, D.K., Chemical stability study of BaCe09 3. Almazouzi, A.; Diaz de la Rubia, T.; Ishino, Nd0 JOJ (< high-temperature proton-conducting 26. Driver, J.H.; Winther, G., Microtextures et S.; Lam, N.Q.; Singh, B.N.; Trinkaus, H.; Victoria, ceramic. 3. Mater. Chem. (1997) v. 7 p. 481-485 heterogeneites de deformation. Rev. Metall. M.; Zinkle, S., Defect production, accumulation (Paris) (1997) p. 1021-1028 and materials performance in an irradiation en- 17. Chen, F.L.; Wang, Ping; ToftSerensen, 0.; vironment. Summary. J. Nucl. Mater. (1997) v. Meng, G.Y.; Peng, D.K., Preparation of Nd-doped 27. Edwards, D.J.; Singh, B.N.; Toft, P.; Eldrup, 251 p. 291-294 BaCeO3 proton-conducting ceramics by homoge- M., Recent results on the neutron irradiation of neous oxalate coprecipitation. 3. Mater. Chem. ITER candidate copper alloys irradiated in DR-3 4. Almazouzi, A.; Victoria, M.; Singh, B.N.; Diaz (1997) v. 7 p. 1533-1539 at 250 °C to 0.3 dpa. In: Fusion materials semi- de la Rubia, T. (eds.), Defect production, accu- annual progress report for the period ending mulation and materials performance in an irra- 18. Chen, F.L.; Toft Serensen, 0.; Meng, G.Y.; December 31, 1996. (1997) p. 183-193 diation environment. Proceedings. International Peng, D.K., Synthesis of Nd-doped barium cerate workshop on defect production, accumulation proton conductor from oxalate coprecipitate 28. Eldrup, M.; Sanders, P.G.; Weertman, J.R., and materials performance in an irradiation en- precursor. 3. Thermal Anal. (1997) v. 49 p. 1255- Positron annihilation study of the influence of vironment, Davos (CH), 2-8 Oct 1996. (Elsevier, 1261 grain size and purity on the annealing behaviour Amsterdam, 1997) (X Nucl. Mater., vol. 251) 300 p. of nano-crystalline copper. Mater. Sci. Forum 19. Chen, F.L.; ToftSerensen, 0.; Meng, G.Y.; (1997) v. 255/257 p. 436-438 5. Armstrong, W.D., Magnetization and mag- Peng, D.K., Preparation of Nd-doped barium ce- netostriction processes in Tb027030Dy0,3.0;o rate through different routes. Solid State Ionics 29. Eldrup, M.; Singh, B.N., Studies of defects Fe]920. J. Appl. Phys. (1997) v. 81 p. 2321-2326 (1997) V. 100 p. 63-72 and defect agglomerates by positron annihilation spectroscopy. J. Nucl. Mater. (1997) v. 251 p. 6. Armstrong, W.D., Burst magnetostriction in 20. Christensen, J.; Gotthj&lp, K.; Kjeldsteen, P., 132-138 Tb03Dy07FeI9. 3. Appl. Phys. (1997) v. 81 p. The effect of surface treatments on the brazing 3548-3554 of iron-based powder metal compacts. Weld. J. 30. Frello, T.; Andersen, N.H.; Madsen, 3.; Kail, (1997) v. 76 p. S239-S244 M.; Zimmermann, M. von; Schmidt, 0.; Poulsen, 7. Armstrong, W.D., The magnetization and H.F.; Schneider, J.R.; Wolf, T., Dynamics of oxy- magnetostriction of Tb0 3Dy0 7Fet 9 fiber actuated 21. Christoffersen, H.; Leffers, Z, Microstructure gen ordering in YBa.,Cu306(i studied by neutron epoxy matrix composites. Mater. Sci. Eng. B and composite deformation pattern for rolled and high-energy synchrotron X-ray diffraction. (1997) V. 47 p. 47-53 brass. Scr. Mater. (1997) v. 37 p. 1429-1434 Physica C (1997) v. 282/287 p. 1089-1090

8. Armstrong, W.D.; Lorentzen, Z, Fiber phase 22. Christoffersen, H.; Leffers, Z, The orienta- 31. Gillespie, J.W.; Hansen, U., Transverse crack- transformation and matrix plastic flow in a room tion of dislocation walls in rolled copper relative ing of composite laminates with interleaves: A temperature tensile strained NiTi shape memory to the crystallographic co-ordinate system. Scr. variational approach. 3. Reinf. Plast. Compos. alloy fibre reinforced 6082 aluminium matrix Mater. (1997) v. 37 p. 2041-2046 (1997) V. 16 p. 1066-1092 composite. Scr. Mater. (1997) v. 36 p. 1037-1043 23. Clausen, B.; Lorentzen, T., Experimental 32. Hansen, N.; Huang, X., Dislocation struc- 9. Bak, J.; Kindl, B., Quantitative analysis of evaluation of a polycrystal deformation modeling tures and flow stress. Mater. Sci. Eng. A (1997) mineral powders by DRIFTS: Determination of scheme using neutron diffraction measurements. v. 234/236 p. 602-605 SrC03 in superconductor precursor powders. Appl. Metall. Mater. Trans. A (1997) v. 28 p. 2537-2541 Spectrosc. (1997) v. 51 p. 1730-1735

10. Berbon, M.Z.; Toft S0rensen, 0.; Langdon, T.G., Creep behavior of superplastic 2.5% yttria- stabilized zirconia. In: Creep and fracture of engineering materials and structures. Earthman, J.C.; Mohamed, F.A. (eds.), (Minerals, Metals and Materials Society, Warrendale, PA, 1997) p. 193-202

11. Berg, R.W.; Nielsen, K.; Poulsen, F.W., Rede-

termination of the crystal structure of Al2Br6. A comparison of three methods. Acta Chem. Scand. (1997) V. 51 p. 442-448

12. Bergenstof Nielsen, C; Horsewell, A.; 0ster- gard, M.J.L., On texture formation of nickel electrodeposits. 3. Appl. Electrochem. (1997) v. 27 p. 839-845

13. Bonanos, N.; Mogensen, M., H2 oxidation at the interface Ni/Sr0995Ce0,5Y00, Ionics (1997) v. 97 p. 483-488

54 33. Hattel, J.H.; Jacobsen, T.K.; Hansen, P.N., Real-time simulation of thermal stresses and creep in plates subjected to transient heat input. IMA 3. Math. Appl. Bus. Ind. (1997) v. 8 p. 123- 141

34. Heinisch, H.L.; Singh, B.N., Stochastic annealing simulation of intracascade defect interactions. J. Nucl. Mater. (1997) v. 251 p. 77-85

35. Huang, X.; Hansen, N., Grain orientation dependence of microstructure in aluminium deformed in tension. Scr. Mater. (1997) v. 37 p. 1-7

36. Hughes, D.A.; Hansen, N., High angle boundaries formed by grain subdivision mechanisms. Acta Mater. (1997) v. 45 p. 3871-3886

37. Hughes, D.A.; Liu, Q.; Chrzan, D.C.; Hansen, K, Scaling of microstructural parameters: Mis- orientations of deformation induced boundaries. Acta Mater. (1997) v. 45 p. 105-112

38. Jacobsen, T.K.; Br0ndsted, P., Strain redistri- 47. Kettunen, P.; Lepisto, T.; Tiainen, T.; Hansen 57. Liu, Q.; Hansen, N., Microstructural study of bution around holes and notches in fiber-rein- N.; Brendsted, P.; Liu, Y.L.; Lohne, 0.; Bauger, 0.; deformation in grain boundary region during forced cross-woven brittle matrix composites. Pedersen, K.; Tweed, J.H.; Young, R.M.K., Alumi- plastic deformation of polycrystaHine alumini- Key Eng. Mater. (1997) v. 127/131 p. 1083-1092 nium alloys with a sharp fatigue limit. FI Patent um. Mater. Sci. Eng. A (1997) v. 234/236 p. 672- 923488 (10 July 1997) 675 39. Jacobsen, T.K.; Serensen, B.F.; Bwndsted, P., Fatigue and frictional heating in ceramic matrix 48. Kindermann, L.; Das, D.; Nickel, H.; Hilpert, 58. Liu, Y.L.; Fischer, G., In situ measurement of composites. Key Eng. Mater. (1997) v. 127/131 K.;Appel, C.C.; Poulsen, F.W., Chemical compat- local strain in a metal matrix composite by the p. 745-752 ibility of (La^Ca^Fe^Mn^Oj with yttriastabi- object grating technique. Scr. Mater. (1997) v. 36 lized zirconia. J. Electrochem. Soc. (1997) v. 144 p. 1187-1194 40. Jean, Y.C.; Eldrup, M.; Schrader, D.M.; West, p. 717-720 R.N. (eds.), Positron annihilation. IPCA-11. 11. 59. Lorentzen, T., Numerical analysis of instru- international conference on positron annihila- 49. Kuzjukevics, A.; Linderoth, S.; Grabis, J., mental resolution effects on strain measure- tion, Kansas City, MO (US), May 1997. (Trans Characterization of yttria-doped zirconia pow- ments by diffraction near surfaces and inter- Tech Publications, Zurich, 1997) (Mater. Sci. ders produced by plasma-chemical method. Solid faces. J. Neutron Res. (1997) v. 5 p. 167-180 Forum, 255/257) 852 p. State Ionics (1996) v. 92 p. 253-260 60. Lorentzen, Z; Clarke, A.P.; Poulsen, H.F.; 41. Jiang, J.Z.; Lu, S.W.; Zhou, Y.X.; Morup, S.; 50. Kuzjukevics, A.; Linderoth, S., Interaction of Garbe, S.; Graafsma, H., Local strain contours Nielsen, K.; Poulsen, F.W.; Berry, F.J.; McMan- NiO with yttria-stabilized zirconia. Solid State around inclusions in wire-drawn Cu/W compos- nus, 3., Correlation of gas sensitive properties Ionics (1997) v. 93 p. 255-261 ites. Composites A (1997) v. 28 p. 667-674 with Fej03-Sn02 ceramic microstnicture prepared by high energy ball milling. Mater. Sci. Forum 51. Kuzjukevics, A.; Linderoth, S., Influence of 61. Pedersen, M.S.; M0rup, S.; Linderoth, S.; (1997) V. 235/238 p. 941-946 NiO on phase stabilization in 6 mol% yttria- Johansson, C; Hanson, M., Inter-particle inter- stabilized zirconia. Mater. Sci. Eng. A (1997) v. actions and the magnetocaloric effect in a sam- 42. Jiang, J.-Z.; Lin, R., Merup, S.; Nielsen, K.; 232 p. 163-167 ple of ultrafine Fe, Jigx particles in Hg. J. Phys. Poulsen, F.W.; Berry, F.J.; Clasen, R., Mechanical Condens. Matter (1997) v. 9 p. 7173-7188 alloying of an immiscible a-Fez03-Sn0; ceramic. 52. Kvick, A.; Poulsen, H.F. (eds.), Local char- Phys. Rev. B (1997) v. 55 p. 11-14 acterisation of materials by synchrotron radia- 62. Poulsen, F.W.; Bruaset, U. (eds.). Experimen- tion. Experiments Division at the European Syn- tal and theoretical methods in fuel cell research. 43. Juul Jensen, D., Simulation of recrystal- chrotron Radiation facility meeting. Grenoble Nordic NEFP workshop on experimental and lization microstructures and textures: Effects of (FR), 12-13 Feb 1997. (ESRF, Grenoble, 1997) vp. theoretical methods in fuel cell research, Geilo preferential growth. Metall. Mater. Trans. A (NO), 5-7 Mar 1997. (NEFP-Secretariat, As, 1997) (1997) V. 28 p. 15-25 53. Larsen, P.H.; Hendriksen, P.V.; Mogensen, M., 118 p. Dimensional stability and defect chemistry of 44. Juul Jensen, D., Effects of orientation corre- doped lanthanum chromites. J. Thermal Anal. 63. Poulsen, H.F.; Garbe, S.; Lorentzen, Z; Juul lations on misorientation distributions in cold- (1997) v. 49 p. 1263-1275 Jensen, D.; Poulsen, F.W.; Andersen, N.H.; Frello, deformed aluminium. Mater. Sci. Eng. A (1997) T.; FeidenhansT, R.; Graafsma, H., Applications V. 234/236 p. 762-765 54. Leffers, Z; Christoffersen, H., The impor- of high-energy synchrotron radiation for struc- tance of grain-to-grain interaction during rolling tural studies of polycrystalline materials. J. Syn- 45. Juul Jensen, D., Applications of orientation deformation of copper. Mater. Sci. Eng. A (1997) chrotron Rad. (1997) v. 4 p. 147-154 mapping by scanning and transmission electron V. 234/236 p. 676-679 microscopy. Ultramicroscopy (1997) v. 67 p. 24- 64. Poulsen, H.F.; Lorentzen, Z; Feidenhans'l, R.; 34 55. Lilholt, H.; Andersen, S.I., Multiple cracking Liu, Y.L., A synchrotron X-ray diffraction study in carbon/epoxy laminates and pre-stressing of of the local residual strains around a single in- 46. 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Liu, Y.L.; Fischer, G., Local strain fields in Mogensen, M., Ceria-based anodes on a YSZ elec- workshop, vol. 1. 10. SOFC workshop, Les Diable- particulate metal matrix composites character- trolyte: Preparation and electrochemical per- rets (CH), 28-31 Jan 1997. McEvoy, A.J.; ized by object grating technique. In: Eleventh formance. In: Solid oxide fuel cells (SOFC-5). Nisancioglu, K. (eds.), (International Energy international conference on composite materials. Proceedings. 5. International symposium on Agency, 1997) p. 84-87 Proceedings. Vol. 3. ICCM-11, Gold Coast, Queens- solid oxide fuel cells, Aachen (DE), 2-5 Jun land (AU), 14-18 Jul 1997. Scott, M.L. (ed.), 1997. Stimming, U.; Singhal, S.C.; Tagawa, H.; 43. Primdahl, S.; Mogensen, M., Gas conversion (Australian Composite Structures Society, Mel- Lehnert, W. (eds.), (The Electrochemical Society, impedance: SOFC anodes in HJ/HJO atmospheres. bourne, 1997) p. 1-9 Pennington, NJ, 1997) (Proceedings Volume 97- In: Solid oxide fuel cells (SOFC-5). Proceedings. 40) p. 540-548 5. International symposium on solid oxide fuel 34. Lorentzen, T.; Armstrong, W.D., In-situ neu- cells, Aachen (DE), 2-5 Jun 1997. Stimming, U.; tron diffraction characterisation of a NiTi fibre 39. Mogensen, M.; Primdahl S.; Juhl, M., Reveal- Singhal, S.C.; Tagawa, H.; Lehnert, W. (eds.), reinforced shape active composite. In: Eleventh ing the mechanisms of SOFC electrodes using a (The Electrochemical Society, Pennington, NJ, international conference on composite materials. combination of AC and DC methods. In: Solid 1997) (Proceedings Volume 97-40) p. 530-539 Proceedings. Vol. 6. ICCM-11, Gold Coast, Queens- oxide fuel cells (SOFC-5). Proceedings. 5. Inter- land (AD), 14-18 Jul 1997. Scott, M.L. (ed.), national symposium on solid oxide fuel cells, 44. Rheinldnder, 3.T.; Nielsen, S.A.; Borum, K.K.; (Australian Composite Structures Society, Mel- Aachen (DE), 2-5 Jun 1997. Stimming, U.; Sing- Gundtoft, H.R, NDE of polymeric composites: A bourne, 1997) p. 230-236 hal, S.C.; Tagawa, H.; Lehnert, W. (eds.), (The comparison of techniques. In: Polymeric compos- Electrochemical Society, Pennington, NJ, 1997) ites - expanding the limits. 18. Ris0 interna- 35. Lorentzen, Z; Liu, Y.L., Experimental charac- (Proceedings Volume 97-40) p. 385-393 tional symposium on materials science, Riso terisation and modelling of phase strain evolu- (DK), 1-5 Sep 1997. Andersen, S.I.; Brandsted, tion in 10vol% Al/SiCw composite during ther- 40. Nielsen, S.A.; Andersen, S.I., Ultrasonic de- P.; Lilholt, H.; Lystrup, Aa.; Rheinlander, J.T.; mo-mechanical loading. In: Eleventh interna- termination of elastic constants of fiber rein- Sarensen, B.F.; Toftegaard, H. (eds.), (Ris0 Na- tional conference on composite materials. Pro- forced composites using a circular aperture array tional Laboratory, Roskilde, 1997) p. 101-125 ceedings. Vol. 3. ICCM-11, Gold Coast, Queens- of transducers. In: Polymeric composites - ex- land (AU), 14-18 Jul 1997. Scott, M.L. (ed.), panding the limits. 18. Ris0 international sym- 45. Singh, B.N.; Zoft, P., Pre- and post-irradia- (Australian Composite Structures Society, Mel- posium on materials science, Risa (DK), 1-5 Sep tion properties of pure iron and low activation bourne, 1997) p. 565-572 1997. Andersen, S.I.; Brandsted, P.; Lilholt, H.; steels. In: Proceedings of the second Milestone Lystrup, Aa.; Rheinlander, J.T.; Sarensen, B.F.; meeting of European laboratories on the devel- 36". Lystrup, Aa., Processing technology for ad- Toftegaard, H. (eds.), (Risa National Laboratory, opment of ferritic/martensitic steels for fusion vanced fibre composites with thermoplastic ma- Roskilde, 1997) p. 455-464 technology. 2. Milestone meeting of European trices. In: Polymeric composites - expanding the laboratories on the development of ferritic/mar- limits. 18. Rise international symposium on ma- tensitic steels for fusion technology, Karlsruhe terials science, Ris0 (DK), 1-5 Sep 1997. Ander- (DE), 9-10 Sep 1996. Daum, E.; Ehrlich, K.; sen, S.I.; Brendsted, P.; Lilholt, H.; Lystrup, Schirra, M. (eds.), (1997) p. 47-51 Aa.; Rheinlander, J.T.; Sarensen, B.F.; Tofte- gaard, H. (eds.), (Ris0 National Laboratory, Roskilde, 1997) p. 69-80

59 46. Sunde, S.; Hendriksen, P.V.,k mathematical 10. Bilde-S0rensen, 3.B.; Thorsen, P.A., The role model for internal reforming at composite an- Lectures, posters and of interfacial structure in diffusional creep. odes for solid oxide fuel cells. In: Solid oxide Boundaries and interfaces in materials: The fuel cells (SOFC-5). Proceedings. 5. International abstracts David A. Smith symposium, Indianapolis, IN symposium on solid oxide fuel cells, Aachen (US), 15-18 Sep 1997. (DE), 2-5 Jun 1997. Stimming, U.; Singhal, S.C.; 1. Bagger, C, Braendselsceller. Fagdidaktisk Tagawa, H.; Lehnert, W. (eds.), (The Electro- kursus i kemi, Middelfart (DK), 3-5 Sep 1997. 11. Bilde-S0rensen, J.B.; Horsewell, A.; Appel, chemical Society, Pennington, NJ, 1997) (Pro- C.C., Low vacuum and environmental SEM - a ceedings Volume 97-40) p. 1329-1338 2. Bagger, C, Superledende band og kabler. comparison. Mikroskopering - nya metoder och Seminar ved Dansk Forening for Materialografis mb'jligheter, Svenska Foreningen for Materi- 47. Suresh, S.; Giannakopoulos, A.E.; J0rgensen, 20-ars jubilaeum, Vejle (DK), 20-22 Nov 1997. alteknik, Goteborg (SE), 5 Nov 1997. 0., Control of indentation cracking through gradients in elastic properties, with applications to 3. Bagger, C, Braendselsceller. LFMK, Fysiklae- 12. Br0ndsted, P., Metoder til maling af mate- polymeric composites. In: Polymeric composites - rerforeningen og Kemilaererforeningen, regional- rialers mekaniske egenskaber. Ris0 'Roadshow'. expanding the limits. 18. Ris0 international sym- kursus, Toftlund (DK), 20 Nov 1997. Danfoss, Nordborg (DK), 3 Feb 1997. posium on materials science, Ris0 (DK), 1-5 Sep 1997. Andersen, S.I.; Br0ndsted, P.; Lilholt, H.; 4. Bentzen, J.; Mathiesen, 1, Liquid phase 13. Bmndsted, P., Elastisk-plastiske egenskaber Lystrup, Aa.; Rheinlander, J.T.; S0rensen, B.F.; sintering of PM materials. Oral presentation at af materialer til hardt belastende maskindele. Toftegaard, H. (eds.), (Ris0 National Laboratory, Joint Nordic conference in powder technology, Rise 'Roadshow'. Danfoss, Nordborg (DK), 3 Feb Roskilde, 1997) p. 169-179 Helsinki (FI), 26-27 Nov 1997. 1997.

48. S0rensen, B.F.; Jacobsen, T.K., R-curve and 5. Bilde-S0rensen, J., Karakterisering af mate- 14. Br0ndsted, P., Bestemmelse af dynamiske bridging law of carbon fibre/epoxy composites. rialer med elektronmikroskopteknikker. Ris0 egenskaber af elastomer- og polymermaterialer. In: Polymeric composites - expanding the limits. 'Roadshow'. Danfoss, Nordborg (DK), 3 Feb 1997. Ris0 'Roadshow'. Danfoss, Nordborg (DK), 3 Feb 18. Ris0 international symposium on materials 1997. science, Ris0 (DK), 1-5 Sep 1997. Andersen, S.I.; 6. Bilde-S0rensen, J.B., Correction methods for Brondsted, P.; Lilholt, H.; Lystrup, Aa.; Rhein- beam skirt effects in X-ray spectra from LVSEMs. 15. Br0ndsted, P., Metoder til maling af mate- lander, J.T.; S0rensen, B.F.; Toftegaard, H. (eds.), Low vacuum SEM symposium, Ornskoldsvik (SE), rialers mekaniske egenskaber. Ris0 'Roadshow'. (Ris0 National Laboratory, Roskilde, 1997) p. 12-13 Feb 1997. Gmndfos, Bjerringbro (DK), 29 May 1997. 491-496 7. Bilde-S0rensen, J.B.; Appel, C.C., X-ray spec- 16. Br0ndsted, P., Udmattelsesegenskaber af 49. Thomsen, N.B., Optimum surface layer of trometry in low vacuum and environmental polymerkompositter; maling af skadesudbredelse transformation toughened ceramics for improved scanning electron microscopes. In: Nordic ceram- baseret pa stivhedsaendringer. Ris0 'Roadshow'. wear performance. In: Advances in fracture re- ics '97. Structural ceramics. Functional ceramics. Grundfos, Bjerringbro (DK), 29 May 1997. search. Vol. 2. 9. International conference on Extended abstracts. Nordic ceramics '97, Ris0 fracture, Sydney (AU), 1-5 Apr 1997. Karihaloo, (DK), 26-27 May 1997. Sarensen, B.F. (ed.), (Ris0 17. Brondsted, P., Materialer til vinger. Ris0s B.L.; Mai, Y.-W.; Ripley, M.I.; Ritchie, R.O. (eds.), National Laboratory, Roskilde, 1997) p. 24-25 vinddag 1997, Risa (DK), 23 Oct 1997. (Pergamon Press, Amsterdam, 1997) p. 1105- 1112 8. Bilde-S0rensen, J.B., Karakterisering af ma- 18. Bwndsted, P., Metoder til maling af mate- terialer ved hjaelp af elektronmikroskopi. Dansk rialers mekaniske egenskaber. IDA - undervis- 50. Toftegaard, H., Elastic constants from simple Naturvidenskabeligt Kursussamvirke. Indvielse af ning, Kolding (DK), 20 Mar 1997. compression tests. In: Polymeric composites - 8 nye videokonference centre pa de danske uni- expanding the limits. 18. Risa international sym- versiteter og Ris0, Ris0 (DK), 15 May 1997. 19. Bmndsted, P.; Jacobsen, T.K., Mechanical posium on materials science, Ris0 (DK), 1-5 Sep performance of fibre reinforced ceramic matrix 1997. Andersen, S.I.; Brendsted, P.; Lilholt, H.; 9. Bilde-Serensen, J.B., Karakterisering af ma- composites - static loading. In: Nordic ceramics Lystrup, Aa.; Rheinlander, J.T.; Sarensen, B.F.; terialer med elektronmikroskopteknikker. Ris0 '97. Structural ceramics. Functional ceramics. Toftegaard, H. (eds.), (Ris0 National Laboratory, 'Roadshow". Grundfos, Bjerringbro (DK), 29 May Extended abstracts. Nordic ceramics '97, Ris0 Roskilde, 1997) p. 497-502 1997. (DK), 26-27 May 1997. S0rensen, B.F. (ed.), (Ris0 National Laboratory, Roskilde, 1997) p. 68-69

Popularized scientific publications

1. Lienert, U.; Hartlaub, S.; Freund, A., Experi- mental shape optimisation of bent crystals. ESRF Newslett. (1997) (no.29) p. 30-31

2. Schroder Pedersen, A., Spray forming af me- talliske materialer. Ris0nyt (1997) (no.4) p. 4-5

3. S0nderberg Petersen, L.; Hansen, N., Ris0- forsker blev Danmarks f0rste kvindelige dr.techn. Ris0nyt (1997) (no.2) p. 14

60 20. Br0ndsted, P.; Skov-Hansen, P., Fatigue properties of high strength materials used in cold forging tools. 30. International Cold Forging Group plenary meeting, 's-Hertogenbosch (NL), 7-10 Sep 1997.

21. Carstensen, J.V., Dislocation microstructures in fatigued polycrystalline brass. 9. Colloquium on fundamental fatigue mechanisms, Erlangen (DE), 9-10 Oct 1997.

22. Carstensen, J.V., Skade ved udmattelse af en-fase materialer. DCAMM 6. interne symposium, Ebeltoft (DK), 17-19 Mar 1997.

23. Carstensen, J.V., Computersimulering af udmattelsesskader. Temara?kke om rustfrit stal, Kolding (DK), 20 Mar 1997.

24. Edwards, D.J.; Singh, B.N.; Toft, P.; Eldrup, Af., Effect of bonding and bakeout thermal cycles on the properties of copper alloys irradiated at 100 degr.C. Poster presentation at the ICFRM-8, Sendai (JP), 26-31 Oct 1997.

25. Eldrup, Af., Positronium localization or non- thermalization in molecular crystals. Foredrag ved Department of Basic Sciences, University of 34. Jacobsen, T.K.; Brendsted, P., Mechanical 42. Larsen, D., Structural and electrical proper- Tokyo, Tokyo (JP), 4 Nov 1997. performance of fiber-reinforced ceramic matrix ties of perovskites. Nordic research course: The composites - fatigue loading. In: Nordic ceramics application of synchrotron radiation in chemis- '97. Structural ceramics. Functional ceramics. 26. Eldrup, M.; Singh, B.N., Influence of compo- try, biology and physics, Sandbjerg (DK), 1-7 Jun Extended abstracts. Nordic ceramics '97, Risa sition, heat treatment and neutron irradiation 1997. (DK), 26-27 May 1997. Sarensen, B.F. (ed.), (Ris0 on the electrical conductivity of copper alloys. National Laboratory, Roskilde, 1997) p. 70-71 Poster presentation at the ICFRM-8, Sendai (JP), 43. Larsen, D.; Poulsen, F.W.; Mogensen, Af., 26-31 Oct 1997. Conductivity of A- and B-site doped LaAlO3, 35. Juul Jensen, D., Hvad sker der i et metal nar LaScOj and LaGa03 perovskites. 3. International 27. Faurholt, T.; Lorentzen, T., Measurements of det rekystalliseres? Ris0 'Roadshow'. Danfoss, symposium on ionic and mixed conducting ce- residual stresses in a sheet metal bending speci- Nordborg (DK), 3 Feb 1997. ramics, Paris (FR), 30 Aug - 5 Sep 1997. men. ICRS-5, Linkoping (SE), Jun 1997. 36. Juul Jensen, D., Anisotrope mekaniske egen- 44. Leffers, T., Mikrostrukturrelaterede modeller skaber. Ris0 'Roadshow'. Danfoss, Nordborg (DK), 28. Golubov, S.I.; Singh, B.N.; Trinkaus, H., Cal- for plastisk deformation. Ris0 'Roadshow'. Dan- 3 Feb 1997. culations of recoil energy effects on defect accu- foss, Nordborg (DK), 3 Feb 1997.

mulation in terms of production bias and loop 1 glide. Poster presentation at the ICFRM-8, Sendai 37. Juul Jensen, D., Can we make and do we 45. Leffers, Z, Tekstur. Ris0 'Roadshow . Grund- (JP), 26-31 Oct 1997. need a 3-D X-ray microscope? The characteriza- fos, Bjerringbro (DK), 29 May 1997. tion of multiscale and stochastic material microstructure and its relation to material aging, IMM 29. Hansen, N., Structural parameters and 46. Leffers, Z, Microstructure - the forgotten strength. McNU'97, summer meeting, Evanston, workshop, La Jolla, CA (US), 24-27 Feb 1997. factor in texture models. Application of textures IL (US), 29 Jun - 2 Jul 1997. in materials research (NASAT-97), Hyderabad 38. Juul Jensen, D., Nye karakteriseringsmeto- (IN), 4-5 Dec 1997. 30. Heinisch, H.; Singh, B.N., Stochastic anneal- der til materiale struktur og egenskaber. Materi- ing simulation of copper under continuous neu- als processing, properties and modelling, Lyngby 47. Leffers, Z, The mystery of brass-type tex- tron irradiation. Poster presentation at the (DK), 19 Nov 1997. ture. Lecture at the Institute of Physics, National ICFRM-8, Sendai (JP), 26-31 Oct 1997. University of Rosario, Rosario (AR), 14 Nov 1997. 39. Juul Jensen, D., Growth during recrystallization. In: Local characterisation of materials 31. Hendriksen, P.M., Geometric requirements of 48. Leffers, T., The two-dimensional ODF of pla- by synchrotron radiation. Experiments Division three electrode setups with solid electrolytes. nar microstructural features. International con- at the European Synchrotron Radiation Facility European workshop on current and potential ference on texture and anisotropy of polycry- meeting, Grenoble (FR), 12-13 Feb 1997. Kvick, distributions in complex electrochemical sys- stals, Clausthal (DE), 22-25 Sep 1997. A.; Poulsen, H.F. (eds.), (ESRF, Grenoble, 1997) tems, Nancy (FR), 29 Aug 1997. p. 183-222 49. Leffers, Z, Research strategies in Europe, in 32. Hendriksen, P.V.; Larsen, P.H.; Jergensen, 0., Denmark and at Ris0 National Laboratory. Lec- Expansion on reduction of doped lanthanum 40. Karjalainen-Roikonen, P.; Pyykkb'nen, M.; ture at CAC, National Commission of Atomic En- chromites and its consequences for the integrity Tahtinen, S.; Singh, B.N.; Toft, P., Effects of neu- ergy, Buenos Aires (AR), 21 Nov 1997. of SOFC stacks. In: Nordic ceramics '97. Struc- tron irradiation on fracture toughness and ten- tural ceramics. Functional ceramics. Extended sile behaviour of copper alloys and their joints 50. Lienert, U.; Schulze, C; Honkimaki, V.; abstracts. Nordic ceramics '97, Ris0 (DK), 26-27 with stainless steel. Poster presentation at the Tschentscher, T.; Garbe, S.; Hignette, 0.; May 1997. S0rensen, B.F. (ed.), (Ris0 National ICFRM-8, Sendai (JP), 26-31 Oct 1997. Horsewell, A.; Lingham, M.; Poulsen, H.F.; Laboratory, Roskilde, 1997) p. 30-31 Thomsen, N.B.; Ziegler, E., Focusing optics for 41. Larsen, D., Conductivity of A- and B-site high energy X-ray diffraction. Synchrotron Re- 33. Horsewell, A., The processing and properties doped LaAl03, LaSc03 and LaGa0s perovskites. search and Instrumentation, (JP), Aug 1997. of electrodeposited layered surface coatings. International School of Materials Science and Layered structural materials, LSM'97, Institute of Technology. 33. Course: Oxygen ion and mixed Materials, Royal Society, London (GB), 28 Nov conductors and their technological applications, 1997. Erice (IT), 13-26 Jul 1997.

61 51. Lienert, U., Focussing high energy optics. 64. Mogensen, M., Er braendselsceller fremtidens 76. Poulsen, F.W., Method for calculating ionic In: Local characterisation of materials by syn- energikonvertere? Energiseminar 1997: Fremti- and electronic defect concentrations in fluorite chrotron radiation. Experiments Division at the dens energiformer. AUC, Aalborg (DK), 12 Aug structure oxides. 3. International symposium on European Synchrotron Radiation Facility meet- 1997. ionic and mixed conducting ceramics, Paris (FR), ing, Grenoble (FR), 12-13 Feb 1997. Kvick, A.; 31 Aug - 5 Sep 1997. Poulsen, H.F. (eds.), (ESRF, Grenoble, 1997) p. 65. Mogensen, M., Revealing the electrode me- 302-320 chanisms of SOFC electrodes using a combination 77. Poulsen, F.W., High temperature fuel cells: of AC and DC methods. International School of Status and spin-offs. Informations/diskussions- 52. Liu, Y.L., Characterization of local strain Materials Science and Technology. 33. Course: nwde med industri- og myndighedsrepraesen- fields in metal matrix composites deformed by Oxygen ion and mixed conductors and their tanter, Nordisk Energiforskningsprogram-Breend- tension. University of Queensland, Brisbane technological applications, Erice (IT), 13-26 Jul selsceller, Goteborg (SE), 12 Dec 1997. (AD), 16 Jul 1997. 1997. 78. Poulsen, H.F., High energy X-ray scattering 53. Lorentzen, T., Karakterisering af residual- 66. Mogensen, M., The processes limiting the for materials science. Nordic research school on spaendinger i industrielle komponenter. Ris0 SOFC performance. 4. Euroconference on solid the application of X-ray synchrotron radiation in 'Roadshow1. Danfoss, Nordborg (DK), 3 Feb 1997. state ionics, Galway (IE), 13-19 Sep 1997. chemistry, biology and physics, Sanderborg (DK), 1-7 Jun 1997. 54. Lorentzen, T., Macro stress mapping. 1997 67. Mogensen, M., Comparison of SOFC with Annual Denver X-ray conference, Steamboat other fuel cell options. International School of 79. Poulsen, H.F., Applications of high-energy Springs, CO (US), 4-8 Aug 1997. Materials Science and Technology. 33. Course: synchrotron radiation within materials science. Oxygen ion and mixed conductors and their 29. Meeting of Danish Crystallographers and 1. 55. Lorentzen, T., From micromechanics to engi- technological applications, Erice (IT), 13-26 Jul DANSYNC annual meeting. DTU, Lyngby (DK), 29- neering. In: Local characterisation of materials 1997. 30 May 1997. by synchrotron radiation. Experiments Division at the European Synchrotron Radiation Facility 68. Mogensen, M., Economics of SOFC and com- 80. Poulsen, H.F., The prospect of a 3D high meeting, Grenoble (FR), 12-13 Feb 1997. Kvick, petitive technologies. International School of energy probe for materials science. In: Local A.; Poulsen, H.F. (eds.), (ESRF, Grenoble, 1997) Materials Science and Technology. 33. Course: characterisation of materials by synchrotron p. 77-98 Oxygen ion and mixed conductors and their radiation. Experiments Division at the European technological applications, Erice (IT), 13-26 Jul Synchrotron Radiation Facility meeting, Grenoble 56. Lorentzen, Z; Clausen, B., Self-consistent 1997. (FR), 12-13 Feb 1997. Kvick, A.; Poulsen, H.F. modelling of lattice strain response and develop- (eds.), (ESRF, Grenoble, 1997) p. 3-24 ment of intergranular residual strains. ICRS-5, 69. Mogensen, M., Solid oxide fuel cell assembly Linkbping (SE), Jun 1997. and fabrication. International School of Materi- 81. Poulsen, H.F., Draft of instrument. In: Local als Science and Technology. 33. Course: Oxygen characterisation of materials by synchrotron 57. Lystrup, Aa., Anvendelsesmuligheder og ion and mixed conductors and their technologi- radiation. Experiments Division at the European produktionsmuligheder for termoplastiske fiber- cal applications, Erice (IT), 13-26 Jul 1997. Synchrotron Radiation Facility meeting, Grenoble kompositter. Roadshow hos Dronningborg Indus- (FR), 12-13 Feb 1997. Kvick, A.; Poulsen, H.F. tries A/S, Randers (DK), 3 Apr 1997. 70. Nielsen, S.A., Bistatic circular array imaging (eds.), (ESRF, Grenoble, 1997) p. 321-333 with gated ultrasonic signals. 23. International 58. Lystrup, Aa., Fremstillingsteknologi for symposium on acoustical imaging, Boston, MA 82. Poulsen, H.F.; Garbe, S.; Juul Jensen, D.; avancerede fiberkompositter. Roadshow hos (US), 13-16 Apr 1997. Lorentzen, T., Three dimensional mapping of Elektro-Isola A/S, Vejle (DK), 21 Oct 1997. materials science properties using high energy 71. Pedersen, O.B., Udmattelse i duplex rustfri synchrotron radiation. In: Seventeenth European 59. Lystrup, Aa., Termoplastiske fiberkompo- stal. Ris0 'Roadshow'. Danfoss, Nordborg (DK), 3 crystallographic meeting. Programme. Book of sitter - fremstilling, egenskaber og anvendelse. Feb 1997. abstracts. ECM - 17, Lisboa (PT), 24-28 Aug 1997. Roadshow hos Adtranz Danmark A/S, Randers (Instituto Superior Tecnico, Lisboa, 1997) p. 58 (DK), 4 Dec 1997. 72. Pedersen, O.B., Fatigue mechanisms in duplex stainless steels. 9. Colloquium on funda- 83. Primdahl, S.; Mogensen, M., Gas conversion 60. Lystrup, Aa., Termoplastiske fiberkompo- mental fatigue mechanisms, Erlangen (DE), 9-10 impedance: SOFC anodes in H2/H20 atmospheres. sitter - fremstilling, egenskaber og anvendelse. Oct 1997. 5. International symposium on solid oxide fuel Seminar for REKOM, TIC Roskilde Amt og Inge- cells, Aachen (DE), 2-5 Jun 1997. mann Maskinfabrik, Gevninge (DK), 10 Dec 1997. 73. Pedersen, O.B., Nye duplex rustfri stal. Tema- raekke om rustfrit stal, Kolding (DK), 20 Mar 84. Pryds, N.H.; Larsen, B., Analysis of the so- 61. Marina, O.A.; Primdahl, S.; Bagger, C; 1997. lidification during the spray deposition process. Mogensen, M., Ceria-based anodes for a high- Joint Nordic conference in powder technology, temperature solid oxide fuel cell. In: Nordic ce- 74. Perry, A.J.; Jensen, H.; Toft S0rensen, 0., Helsinki (FI), 26-27 Nov 1997. ramics '97. Structural ceramics. Functional ce- Comparison of production methods for oxide ramics. Extended abstracts. Nordic ceramics '97, sensors based on semiconducting magnesium 85. Rasmussen, T., Atomistic simulations of the Ris0 (DK), 26-27 May 1997. Serensen, B.F. (ed.), doped strontium titanate. In: Nordic ceramics structure, energetics and cross slip of screw dis- (Ris0 National Laboratory, Roskilde, 1997) p. 32- '97. Structural ceramics. Functional ceramics. locations in copper. Materials Research Society, 33 Extended abstracts. Nordic ceramics '97, Ris0 Spring meeting 1997, San Francisco, CA (US), 31 (DK), 26-27 May 1997. Sorensen, B.F. (ed.), (Ris0 Mar - 4 Apr 1997. 62. Mogensen, K.S.; B0ttiger, J.; Eskildsen, S.S.; National Laboratory, Roskilde, 1997) p. 40-41 Mathiasen, C; Thomsen, N.B., Microstructural, 86. Rasmussen, T., Atomistic determination of mechanical and tribological properties of PA-CVD 75. Poulsen, F.W., Method for calculating ionic cross-slip pathway. Multiscale modeling and TiN coatings: A parametric study. 24. Interna- and electronic defect concentrations in Y-stabi- grand challenge. Problems in materials research, tional conference on metallurgical coatings and lised zirconia. In: Nordic ceramics '97. Structural Lyon (FR), 23-25 Oct 1997. thin films (ICMCTF 97), San Diego, CA (US), 21- ceramics. Functional ceramics. Extended ab- 25 Apr 1997. stracts. Nordic ceramics '97, Ris0 (DK), 26-27 87. Rheinlander, J., Quantitative condition mo- May 1997. Sarensen, B.F. (ed.), (Ris0 National nitoring and data extraction by digital radiogra- 63. Mogensen, K.S.; Thomsen, N.B.; Horsewell, Laboratory, Roskilde, 1997) p. 75-77 phy and phosphor plate radiology. In: Advances A.; Eskildsen, S.S.; Mathiasen, C; B0ttiger, J., in signal processing for non destructive evalua- Microstructural, mechanical and tribological tion of materials. 3. International workshop on properties of PA-CVD TiN coatings. International advances in signal processing for non destructive conference on advanced materials (ICAM'97), evaluation of materials, Quebec (CA), 5-8 Aug Strasbourg (FR), 16-20 Jun 1997. 1997. (Universite Laval, Quebec, 1997) p. 65

62 88. R0mer Hansen, J.; Mogensen, M.; Jacobsen, T., Perovskite oxides for interconnects for solid oxide fuel cells. International School of Materials Science and Technology. 33. Course: Oxygen ion and mixed conductors and their technological applications, Erice (IT), 13-26 Jul 1997.

89. Sarraute, S.; Toft Serensen, 0.; Hansen, E.R., Sequentially stacking and pressing: New method to produce functionnally graded multilayer ceramics. In: Nordic ceramics '97. Structural ceramics. Functional ceramics. Extended abstracts. Nordic ceramics '97, Ris0 (DK), 26-27 May 1997. Serensen, B.F. (ed.), (Ris0 National Laboratory, Roskilde, 1997) p. 57-58

90. Singh, B.N., Results and analysis of screening and post-irradiation annealing experiments on copper alloys. ITER working meeting on development and irradiation tests of Cu/SS and Be/Cu/SS joints (tasks T212 and T213), Garching (DE), 24-26 Mar 1997.

91. Singh, B.N., Status and current conclusions of ongoing ITER task T-213 on copper and copper alloys. EUHT/JCT review meeting on materials and joining technology tasks, Ris0 (DK), 19- WO.Singh, B.N.; Horsewell, A.; Toft, P., Effects of 108. Thomsen, N.B.; Lienert, U.; Garbe, S.; 20 Nov 1997. neutron irradiation on microstructure and me- Honkimaki, V.; Poulsen, H.F.; Horsewell, A., chanical properties of pure iron nd low activa- Strain profiling in thin films by synchrotron 92. Singh, B.N., Recent results on effects of tion steels. Poster presentation at the ICFRM-8, radiation - a novel technique. International con- irradiation on physical and mechanical proper- Sendai (JP), 26-31 Oct 1997. ference on advanced materials (ICAM'97), Stras- ties of copper alloys. Workshop on materials and bourg (FR), 16-20 Jun 1997. joints for in-vessel components, Garching (DE), lOl.Skov-Hansen, P.; Bay, N.; Grenbaek, J.; 1-5 Dec 1997. Br0ndsted, P., Low-cycle fatigue in cold forging 109. Toft Serensen, 0., Termisk analyse af mate- dies: Life analysis, a case study on the influence rialer. Ris0 'Roadshow'. Danfoss, Nordborg (DK), 3 93. Singh, B.N., Evidence of spectral and rate of properties in hard, brittle tool materials. 30. Feb 1997. effects on damage accumulation in metals and International Cold Forging Group plenary meet- alloys. IFMIF-users group meeting, IMR, Tohoku ing, s'-Hertogenbosch (NL), 7-10 Sep 1997. 230. Toft S0rensen, 0., Introduction to Ris0 and University, Sendai (JP), 1 Nov 1997. to the Materials Research Department, Ris0 Na- 102.Stubbins, J.F.; Singh, B.N.; Toft, P., Fatigue tional Laboratory, Denmark. Lecture at Univer- 94. Singh, B.N., Radiation hardening and plastic performance of copper and copper alloys before sity of Beijing, Beijing (CN), 26 Sep 1997. instability in neutron irradiated Mo and Mo- and after irradiation to 0.3 dpa at 50 and 100 °C. alloys. IEA international workshop on refractory Poster presentation at the ICFRM-8, Sendai (JP), 111. Toft Serensen, 0., Introduction to Materials metals and alloys for fusion applications, Sendai 26-31 Oct 1997. Research Department, Ris0 National Laboratory, (JP), 24-5 Oct 1997. Denmark, and to computer controlled thermal 103.Sdrby, L; Poulsen, F.W.; Poulsen, H.F.; Garbe,analysis. Lecture at Academia Sinica, Beijing 95. Singh, B.N., Damage production, accumula- S., An in-situ diffraction study of a solid oxide (CN), 29 Sep 1997. tion and consequences: A review. International fuel cell system. EPDIC 5, Parma (IT), 1997. workshop on radiation damage in metals, Liver- HZ.Toft S0rensen, O., Structural ceramics. Defect pool (GB), 17-18 Apr 1997. WA.S0re.nssn, B.F., Kontrolleret revnevaekst i chemistry. Sensor based on oxygen ion conduct- sprade materialer observeret i skanningelek- ing materials. Sensors based on semiconductors. 96. Singh, B.N., Consequences of atomic displa- tronmikroskop. Ris0 'Roadshow'. Grundfos, Computer-controlled thermal analysis. Lecture cements in crystalline solids. Seminar given at Bjerringbro (DK), 29 May 1997. series at University of Science and Technology of the Hong Kong Polytechnic University, Hong China (USTC), Hefei (CN), 30 Sep - 14 Nov 1997. Kong (CN), 6 Nov 1997. lO5.S0rensen, B.F.; Horsewell, A., Fracture mechanics testing: Stable crack growth in mono- 113. Toft S0rensen, O., Ceramic research and de- 97. Singh, B.N., Impacts of damage production lithic and layered ceramics. In: Nordic ceramics velopment projects at the Materials Research and accumulation on materials performance in '97. Structural ceramics. Functional ceramics. Department, Risa National Laboratory, Denmark. irradiation environment. 8. International confer- Extended abstracts. Nordic ceramics '97, Ris0 Lecture at Xidian University, Xian (CN), 14-20 ence on fusion reactor materials (ICFRM-8), Sen- (DK), 26-27 May 1997. S0rensen, B.F. (ed.), (Ris0 Nov 1997. dai (JP), 26-31 Oct 1997. National Laboratory, Roskilde, 1997) p. 61-62 114. Toft S0rensen, 0., Design af og med keramik. 98. Singh, B.N.; Evans, J.H.; Horsewell, A.; Toft, lO6.S0rensen, B.F.; Sarraute, S.; Horsewell, A., ID-forum, Horsens (DK), 27 Feb 1997. P., Effects of neutron irradiation on microstruc- Thermally induced delamination of multilayers. ture and deformation behaviour of mono- and In: Nordic ceramics '97. Structural ceramics. 115.Vase, P.; Skov-Hansen, P.; Han, Z.; Poulsen, polycrystalline molybdenum and its alloys. Pos- Functional ceramics. Extended abstracts. Nordic H.F.; Frello, T., Bi-2223 tapes for power applica- ter presentation at the ICFRM-8, Sendai (JP), 26- ceramics '97, Rise (DK), 26-27 May 1997. Saren- tions. EUCAS-97, Twente (NL), 30 Jun - 3 Jul 31 Oct 1997. sen, B.F. (ed.), (Ris0 National Laboratory, Ros- 1997. kilde, 1997)p. 59-60 99. Singh, B.N.; Horsewell, A.; Toft, P., Micro- 116. Zheng, H.; Jensen, H.; Toft Serensen, 0., structure and deformation behaviour of neutron 107. Thomsen, N.B., Optimum surface layer of SrMg^Tij x03a - a promising oxygen-sensing mate- irradiated iron and low activation ferritic/mar- transformation toughened ceramics for improved rial. In: Nordic ceramics '97. Structural ceramics. tensitic steels. IEA workshop on reduced activa- wear performance. 1. World tribology conference, Functional ceramics. Extended abstracts. Nordic tion ferritic/martensitic steels, Tokyo (JP), 3-4 London (GB), Sep 1997. ceramics '97, Rise (DK), 26-27 May 1997. S0ren- Nov 1997. sen, B.F. (ed.), (Ris0 National Laboratory, Ros- kilde, 1997) p. 36-37

63 ACRONYMS, ABBREVIATIONS, ETC.

AAU Aalborg University EUCLID European Cooperation OU University of Odense for the Long term In Defense AU Aarhus University PAS Positron annihilation EUREKA Association for European spectroscopy BET A method for measuring surface Market oriented R&D area of powder named after PEI Polyetherimide Brunauer, Emmett and Teller FCC Face centered cubic. A crystal structure PET Polyethyleneterephtalate

BiSCCO Bi2Sr2Ca2Cu3010. A material with superconducting properties FEM The finite element method PLC Programable logical controller

BRITE An EU programme, Basic HASYLAB A synchrotron radiation PMC Polymer matrix composites Research in Industrial Technology laboratory in Hamburg, Germany for Europe SEM Scanning electron microscope ITER International Thermo-nuclear CMC Ceramic matrix composites Experimental Reactor SFT Stacking fault tetrahedron

COM Crystal orientation microscopy IVC Engineering Science Centre. A SIA Self-interstitial atom programme under the Danish CVD Chemical vapour deposition Technical Research Council SOFC Solid oxide fuel cell. High tech ceramic fuel cells dpa Displacements per atom JOULE Joint Opportunities for Unconventional or Long-term Energy TEM Transmission electron DR3 Danish Reactor 3. A nuclear Supply. An EU programme on non- microscopy research reactor at Ris0 nuclear energy and rational exploitation of energy UCT Ultrasound computed DTU The Technical University of tomography Denmark KU University of Copenhagen YSZ Yttria stabilized zirconia EBSP Electron back-scattering LEU Low enriched uranium. Fuel for patterns nuclear test reactors

EDS Energy dispersive (X-ray) LIP Large Installation Programme spectrometry LSC Lanthanum strontium chromite. EELS Electron energy loss A ceramic material used as spectrometry interconnect in SOFCs.

EFP The Energy Research LSM Lanthanum strontium Programme of the Danish Ministry of manganite. A porous ceramic Environment and Energy material used in SOFCs

ELKRAFT The electrical utility group MMC Metal matrix composites of the Danish island Zealand MUP The Danish Materials ELSAM The electrical utility group of Technology Programme the Danish mainland Jutland and the island Funen NorFa Nordic Academy for Advanced Study. An organization set up by the ESEM Environmental scanning Nordic Council to promote electron microscope educational activities for research students ESRF European Synchrotron Radiation Facility ODF Orientation distribution function

64 Ris0 reports its activities in 1997 in the following ten publications: Ris0 Annual Report, Ris0 Business Statement (only available in Danish), Ris0 Publication Activities and the annual progress reports of the seven research departments. The publications and further information on Ris0 is available from the web site www.risoe.dk. Printed copies of the reports are available from the Information Service Department, phone +45 4677 4004, email [email protected], fax +45 4677 4013.