DOCSLIB.ORG

STRUCTURE of MATERIALS the Key to Its Properties

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
STRUCTURE of MATERIALS the Key to Its Properties STRUCTURESTRUCTURE OFOF MATERIALSMATERIALS The Key to its Properties AA MultiscaleMultiscale PerspectivePerspective Anandh Subramaniam Materials and Metallurgical Engineering INDIAN INSTITUTE OF TECHNOLOGY KANPUR Kanpur- 208016 Email: [email protected] http://home.iitk.ac.in/~anandh Jan 2009 OUTLINEOUTLINE Properties of Materials The Scale of “Microstructures” Crystal Structures + Defects Microstructure With Examples from the Materials World PROPERTIES Structure sensitive Structure Insensitive E.g. Yield stress, Fracture toughness E.g. Density, Elastic Modulus Structure Microstructure What determines the properties? Cannot just be the composition! Few 10s of ppm of Oxygen in Cu can degrade its conductivity Cannot just be the amount of phases present! A small amount of cementite along grain boundaries can cause the material to have poor impact toughness Cannot just be the distribution of phases! Dislocations can severely weaken a crystal Cannot just be the defect structure in the phases present! [1] The presence of surface compressive stress toughens glass Phases & Their Distribution Composition Residual Stress Defect Structure [1] Metals Handbook, Vol.8, 8th Edition, ASM, 1973 Length Scales Involved Nucleus Atom Crystal Microstructure Component Defects Dislocation Stress fields Angstroms → Nanometers Microns Centimeters Unit Cell* Crystalline Defects Microstructure Component Grain Size *Simple Unit Cells • Casting Thermo-mechanical • Metal Forming Treatments • Welding Crystal • Powder Processing • Machining Atom Structure Microstructure Component • Avoid Stress Concentrators Electro- • Good Surface Finish magnetic Phases + Defects • Vacancies • Crystalline Structure • Dislocations • Quasicrystalline Residual based • Twins + • Amorphous • Stacking Faults Stress • Grain Boundaries • Ferromagnetic Property • Voids • Ferroelectric based • Cracks • Superconducting Processing determines shape and microstructure of a component • Casting Thermo-mechanical • Metal Forming Treatments • Welding Crystal • Powder Processing • Machining Atom Structure Microstructure Component • Avoid Stress Concentrators Electro- • Good Surface Finish magnetic Phases + Defects & their distribution • Vacancies • Crystalline Structure • Dislocations • Quasicrystalline Residual based • Twins + • Amorphous • Stacking Faults Stress • Grain Boundaries • Ferromagnetic Property • Voids • Ferroelectric based • Cracks • Superconducting Processing determines shape and microstructure of a component METAL SEMI-METAL BAND STRUCTURE ATOMIC SEMI-CONDUCTOR INSULATOR STATE / VISCOSITY LIQUID GAS SOLID LIQUID CRYSTALS STRUCTURE AMORPHOUS QUASICRYSTALS RATIONAL CRYSTALS APPROXIMANTS SIZE NANO-QUASICRYSTALS NANOCRYSTALS Crystal Atom Structure Microstructure Component Electro- magnetic Why is BCC Iron the stable form of Iron at room temperature and not the FCC form of Iron? 1 Atm G vs T showing regions of stability of FCC and BCC Iron (Computed using thermo-calc software and database developed at the Royal Institute of Technology, Stockholm) The Structure of Materials, S.M. Allen & E.L. Thomas, John Wiley & Sons, Inc. New York, 1999. Microstructure This functional definition of “microstructure” includes all lengthscales Phases + Defects • Vacancies • Dislocations Residual • Twins + • Stacking Faults Stress • Grain Boundaries • Voids • Cracks Microstructure Residual Phases + Defects + Stress • Vacancies • Dislocations • Twins • Stacking Faults • Grain Boundaries • Voids • Cracks Microstructure Residual Phases + Defects + Stress • Vacancies • Dislocations Defects (Crystalline) • Vacancies • Twins • Dislocations • Stacking Faults • Grain Boundaries Microstructural • Phase Transformation • Voids • Voids • Cracks • Cracks Component • Stress corrosion cracking • + Residual Surface Compressive Stress CRYSTALCRYSTAL STRUCTURESSTRUCTURES Crystal = Lattice (Where to repeat) + Motif (What to repeat) + = Unit cell of BCC lattice Crystal = Space group (how to repeat) + Asymmetric unit (Motif’: what to repeat) Progressive lowering of symmetry amongst the 7 crystal systems Cubic Hexagonal Tetragonal Trigonal Orthorhombic Monoclinic Increasing symmetry Triclinic Arrow marks lead from supergroups to subgroups 1. Cubic Crystals a = b= c = = = 90 º • Simple Cubic (P) [2] • Body Centred Cubic (I) – BCC • Face Centred Cubic (F) - FCC 4 2 Vapor grown NiO crystal Point groups 23, 3m,4 ,3m 432, 3 Tetrakaidecahedron m m (Truncated Octahedron) Pyrite Cube [1] [1] Fluorite Garnet [1] Dodecahedron [1] http://www.yourgemologist.com/crystalsystems.html Octahedron [2] L.E. Muir, Interfacial Phenomenon in Metals, Addison-Wesley Publ. co. Crystals and Properties (The symmetry of) Any physical property of a crystal has at least the symmetry of the crystal Crystals are anisotropic with respect to most properties The growth shape of a (well grown) crystal has the internal symmetry of the crystal Polycrystalline materials or aggregates of crystals may have isotropic properties (due to averaging of may randomly oriented grains) The properties of a crystal can be drastically altered in the presence of defects (starting with crystal defects) CLASSIFICATION OF DEFECTS BASED ON DIMENSIONALITY 0D 1D 2D 3D (Point defects) (Line defects) (Surface / Interface) (Volume defects) Twins Vacancy Dislocation Surface Interphase Precipitate Impurity Disclination boundary Faulted Frenkel Dispiration Grain region defect boundary Voids / Schottky Twin Cracks defect boundary Stacking Thermal faults vibration Anti-phase boundaries 0D (Point defects) Vacancy Non-ionic Interstitial Impurity crystals Substitutional 0D (Point defects) Frenkel defect Ionic Other ~ crystals Schottky defect Imperfect point-like regions in the crystal about the size of 1-2 atomic diameters Vacancy Missing atom from an atomic site Atoms around the vacancy displaced Tensile stress field produced in the vicinity Tensile Stress Fields Relative size Interstitial Compressive Impurity Stress Fields Substitutional Compressive stress fields SUBSTITUTIONAL IMPURITY Tensile Stress Foreign atom replacing the parent atom in the crystal Fields E.g. Cu sitting in the lattice site of FCC-Ni INTERSTITIAL IMPURITY Foreign atom sitting in the void of a crystal E.g. C sitting in the octahedral void in HT FCC-Fe Interstitial C sitting in the octahedral void in HT FCC-Fe rOctahedral void / rFCC atom = 0.414 rFe-FCC = 1.29 Å rOctahedral void = 0.414 x 1.29 = 0.53 Å rC = 0.71 Å Compressive strains around the C atom Solubility limited to 2 wt% (9.3 at%) Interstitial C sitting in the octahedral void in LT BCC-Fe rTetrahedral void / rBCC atom = 0.29 rC = 0.71 Å rFe-BCC = 1.258 Å rTetrahedral void = 0.29 x 1.258 = 0.364 Å ► But C sits in smaller octahedral void- displaces fewer atoms Severe compressive strains around the C atom Solubility limited to 0.008 wt% (0.037 at%) Equilibrium Concentration of Vacancies Formation of a vacancy leads to missing bonds and distortion of the lattice The potential energy (Enthalpy) of the system increases Work required for the formaion of a point defect → Enthalpy of formation (H ) [kJ/mol or eV/defect] f Though it costs energy to form a vacancy its formation leads to increase in configurational entropy above zero Kelvin there is an equilibrium number of vacancies G = H T S SkConfig ln( ) Crystal Kr Cd Pb Zn Mg Al Ag Cu Ni kJ / mol 7.7 38 48 49 56 68 106 120 168 eV / vacancy 0.08 0.39 0.5 0.51 0.58 0.70 1.1 1.24 1.74 G (perfect crystal) T (ºC) n/N 500 1 x 1010 1000 1 x 105 4 Gmin 1500 5 x 10 2000 3 x 103 Equilibrium Hf = 1 eV/vacancy concentration 18 G (Gibbs energy) free G (Gibbs = 0.16 x 10 J/vacancy n (number of vacancies) Certain equilibrium number of vacancies are preferred at T > 0K Vacancies play a role in: Diffusion Climb Electrical conductivity Creep etc. 1D (Line defects) The shear modulus of metals is in the range 20 – 150 GPa G The theoretical shear stress will be m 2 in the range 3 – 30 GPa Actual shear stress is 0.5 – 10 MPa I.e. (Shear stress)theoretical > 100 * (Shear stress)experimental !!!! DISLOCATIONS Dislocations weaken the crystal DISLOCATIONS EDGE MIXED SCREW Usually dislocations have a mixed character and Edge and Screw dislocations are the ideal extremes Conservative Motion of dislocations (Glide) On the slip plane Motion of Edge dislocation Non-conservative Motion of dislocation (Climb) to the slip plane For edge dislocation: as b t → they define a plane → the slip plane Climb involves addition or subtrac tion of a row of atoms below the half plane ► +ve climb = climb up → removal of a plane of atoms ► ve climb = climb down → addition of a plane of atoms Mixed dislocations b t b Pure screw Pure Edge Role of Dislocations Creep Diffusion Fatigue (Pipe) Fracture Slip Structural Incoherent Twin Grain boundary (low angle) Semicoherent Interfaces Cross-slip Disc of vacancies Creep Dislocation climb ~ edge dislocation mechanisms in crystalline Vacancy diffusion materials Grain boundary sliding 2D (Surface / Interface) Grain Boundary The grain boundary region may be distorted with atoms belonging to neither crystal The thickness may be of the order of few atomic diameters The crystal orientation changes abruptly at the grain boundary In an low angle boundary the orientation difference is < 10º In the low angle boundary the distortion is not so drastic as the high-angle boundary → can be described as an array of dislocations Grain boundary energy is responsible for grain growth on heating ~ (>0.5T ) m Large grains grow at the expense of smaller ones
Load more

Recommended publications
  • Ceramics Overview: Classification by Microstructure and Processing Methods
    Clinical Ceramics overview: classification by microstructure and processing methods Edward A. McLaren 1 and Russell Giordano 2 Abstract The plethora of ceramic systems available today for all types of indirect restorations can be confusing and overwhelming for the clinician. Having a better understanding of them is important. In this article, the authors use classification systems based on microstructural components of ceramics and the processing techniques to help illustrate the various properties. Introduction component atoms, and may exhibit ionic or covalent Many different types of ceramic systems have been bonding. Although ceramics can be very strong, they are also introduced in recent years for all types of indirect extremely brittle and will catastrophically fail after minor restorations, from very conservative nonpreparation veneers, flexure. Thus, these materials are strong in compression but to multi-unit posterior fixed partial dentures and everything weak in tension. in between. Understanding all the different nuances of Contrast that with metals: metals are non-brittle (display materials and material processing systems is overwhelming elastic behaviour) and ductile (display plastic behaviour). This and can be confusing. This article will cover what types of is because of the nature of the interatomic bonding, which is ceramics are available based on a classification of the called metallic bonds; a cloud of shared electrons that can microstructural components of the ceramic. A second, easily move when energy is applied defines these bonds. This simpler classification system based on how the ceramics are is what makes most metals excellent conductors. Ceramics can processed will give the main guidelines for their use. be very translucent to very opaque.
    [Show full text]
  • Texture and Microstructure
    Texture and Microstructure • Microstructure contains far more than qualitative descriptions (images) of cross-sections of materials. • Most properties are anisotropic •it is important to quantitatively characterize the microstructure including orientation information (texture). In latin, textor means weaver In materials science, texture way in which a material is woven. Polycrystalline material is constituted from a large number of small crystallites (limited volume of material in which periodicity of crystal lattice is present). Each of these crystallites has a specific orientation of the crystal lattice. A randomly texture sheet A strongly textured sheet The cube texture (001) ND (Sheet Normal Direction) [100] RD (Sheet Rolling Direction) Crystallographic texture is the orientation distribution of crystallites in a polycrystalline material Texture :Metallurgists and Materials Scientists Fabric :Geologists and Mineralogists Preferred Orientation :Everybody Why textures? Texture influences the following properties: •Elastic modulus •Yield strength •Tensile ductility and strength •Formability •Fatigue strength •Fracture toughness •Stress corrosion cracking •Electrical and Magnetic properties Major fields of application A. Conventional • Aluminium industry • Steel industry • LC steels • Electrical steels • Titanium alloys • Zirconium base nuclear grade alloys B. Modern • High Tc superconductors • Thin films for semiconducting and magnetic devices • Bulk magnetic materials • Structural Ceramics • Polymers Beverage Cans Aluminium beverage
    [Show full text]
  • Introduction to Material Science and Engineering Presentation.(Pdf)
    Introduction to Material Science and Engineering Introduction What is material science? Definition 1: A branch of science that focuses on materials; interdisciplinary field composed of physics and chemistry. Definition 2: Relationship of material properties to its composition and structure. What is a material scientist? A person who uses his/her combined knowledge of physics, chemistry and metallurgy to exploit property-structure combinations for practical use. What are materials? What do we mean when we say “materials”? 1. Metals 2. Ceramics 3. Polymers 4. Composites - aluminum - clay - polyvinyl chloride (PVC) - wood - copper - silica glass - Teflon - carbon fiber resins - steel (iron alloy) - alumina - various plastics - concrete - nickel - quartz - glue (adhesives) - titanium - Kevlar semiconductors (computer chips, etc.) = ceramics, composites nanomaterials = ceramics, metals, polymers, composites Length Scales of Material Science • Atomic – < 10-10 m • Nano – 10-9 m • Micro – 10-6 m • Macro – > 10-3 m Atomic Structure – 10-10 m • Pertains to atom electron structure and atomic arrangement • Atom length scale – Includes electron structure – atomic bonding • ionic • covalent • metallic • London dispersion forces (Van der Waals) – Atomic ordering – long range (metals), short range (glass) • 7 lattices – cubic, hexagonal among most prevalent for engineering metals and ceramics • Different packed structures include: Gives total of 14 different crystalline arrangements (Bravais Lattices). – Primitive, body-centered, face-centered Nano Structure – 10-9 m • Length scale that pertains to clusters of atoms that make up small particles or material features • Show interesting properties because increase surface area to volume ratio – More atoms on surface compared to bulk atoms – Optical, magnetic, mechanical and electrical properties change Microstructure – 10-6 • Larger features composed of either nanostructured materials or periodic arrangements of atoms known as crystals • Features are visible with high magnification in light microscope.
    [Show full text]
  • Correlation Between Crystal Structure, Surface/Interface Microstructure, and Electrical Properties of Nanocrystalline Niobium Thin Films
    nanomaterials Article Correlation between Crystal Structure, Surface/Interface Microstructure, and Electrical Properties of Nanocrystalline Niobium Thin Films L. R. Nivedita 1, Avery Haubert 2, Anil K. Battu 1,3 and C. V. Ramana 1,3,* 1 Center for Advanced Materials Research, University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968, USA; [email protected] (L.R.N.); [email protected] (A.K.B.) 2 Department of Physics, University of California, Santa Barbara, Broida Hall, Santa Barbara, CA 93106, USA; [email protected] 3 Department of Mechanical Engineering, University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968, USA * Correspondence: [email protected]; Tel.: +1-915-747-8690 Received: 10 May 2020; Accepted: 26 June 2020; Published: 30 June 2020 Abstract: Niobium (Nb) thin films, which are potentially useful for integration into electronics and optoelectronics, were made by radio-frequency magnetron sputtering by varying the substrate temperature. The deposition temperature (Ts) effect was systematically studied using a wide range, 25–700 ◦C, using Si(100) substrates for Nb deposition. The direct correlation between deposition temperature (Ts) and electrical properties, surface/interface microstructure, crystal structure, and morphology of Nb films is reported. The Nb films deposited at higher temperature exhibit a higher degree of crystallinity and electrical conductivity. The Nb films’ crystallite size varied from 5 to 9 ( 1) nm and tensile strain occurs in Nb films as Ts increases. The surface/interface morphology of ± the deposited Nb films indicate the grain growth and dense, vertical columnar structure at elevated Ts. The surface roughness derived from measurements taken using atomic force microscopy reveal that all the Nb films are characteristically smooth with an average roughness <2 nm.
    [Show full text]
  • Rotary Friction Welding of Inconel 718 to Inconel 600
    metals Article Rotary Friction Welding of Inconel 718 to Inconel 600 Ateekh Ur Rehman * , Yusuf Usmani, Ali M. Al-Samhan and Saqib Anwar Department of Industrial Engineering, College of Engineering, King Saud University, Riyadh 11451, Saudi Arabia; [email protected] (Y.U.); [email protected] (A.M.A.-S.); [email protected] (S.A.) * Correspondence: [email protected]; Tel.: +966-1-1469-7177 Abstract: Nickel-based superalloys exhibit excellent high temperature strength, high temperature corrosion and oxidation resistance and creep resistance. They are widely used in high temperature applications in aerospace, power and petrochemical industries. The need for economical and efficient usage of materials often necessitates the joining of dissimilar metals. In this study, dissimilar welding between two different nickel-based superalloys, Inconel 718 and Inconel 600, was attempted using rotary friction welding. Sound metallurgical joints were produced without any unwanted Laves or delta phases at the weld region, which invariably appear in fusion welds. The weld thermal cycle was found to result in significant grain coarsening in the heat effected zone (HAZ) on either side of the dissimilar weld interface due to the prevailing thermal cycles during the welding. However, fine equiaxed grains were observed at the weld interface due to dynamic recrystallization caused by severe plastic deformation at high temperatures. In room temperature tensile tests, the joints were found to fail in the HAZ of Inconel 718 exhibiting good ultimate tensile strength (759 MPa) without a significant loss of tensile ductility (21%). A scanning electron microscopic examination of the fracture surfaces revealed fine dimpled rupture features, suggesting a fracture in a ductile mode.
    [Show full text]
  • Introduction to Microstructure
    Materials and Minerals Science Practical 17 CP1 Course C: Microstructure Introduction to microstructure 1.1 What is microstructure? When describing the structure of a material, we make a clear distinction between its crystal structure and its microstructure. The term ‘crystal structure’ is used to describe the average positions of atoms within the unit cell, and is completely specified by the lattice type and the fractional coordinates of the atoms (as determined, for example, by X-ray diffraction). In other words, the crystal structure describes the appearance of the material on an atomic (or Å) length scale. The term ‘microstructure’ is used to describe the appearance of the material on the nm-cm length scale. A reasonable working definition of microstructure is: “The arrangement of phases and defects within a material.” Microstructure can be observed using a range of microscopy techniques. The microstructural features of a given material may vary greatly when observed at different length scales. For this reason, it is crucial to consider the length scale of the observations you are making when describing the microstructure of a material. In this course you will learn about how and why microstructures form, and how microstructures are observed experimentally. Most importantly, microstructures affect the physical properties and behaviour of a material, and we can tailor the microstructure of a material to give it specific properties (this is the subject of the next course). The microstructures of natural minerals provide information about their complex geological history. Microstructure is a fundamental part of all materials and minerals science, and these themes will be expanded on in subsequent courses.
    [Show full text]
  • Understanding Materials Microstructure and Behavior at the Mesoscale A.D
    Understanding materials microstructure and behavior at the mesoscale A.D. Rollett , G.S. Rohrer , and R.M. Suter Taking the mesoscale to mean length and time scales at which a material’s behavior is too complex to be understood by construction from the atomistic scale, we focus on three- dimensional characterization and modeling of mesoscale responses of polycrystals to thermal and mechanical loading. Both elastic and plastic internal structural responses are now accessible via high-energy x-ray probes. The combination of diffraction experiments and computed tomography, for example, is yielding new insights into how void formation correlates with microstructural features such as grain boundaries and higher-order junctions. The resulting large, combined data sets allow for validation of micromechanical and thermal simulations. As detectors improve in resolution, quantum effi ciency, and speed of readout, data rates and data volumes present computational challenges. Spatial resolutions approach one micrometer, while data sets span a cubic millimeter. Examples are given of applications to tensile deformation of copper, grain growth in nickel and titanium, and fatigue cracks in superalloys. Introduction Dislocations, in particular, are well understood as individual The mesoscale is a crucial realm in materials science, espe- defects where an example of a well-established method is cially for polycrystalline materials. Put as succinctly as pos- the calculation of the Peierls stress required to move them sible, a mesoscale property is an attribute of a material that through a lattice. 2 Plastic deformation presents challenges cannot be straightforwardly constructed from properties at the because it generates large dislocation densities on multiple slip atomic scale.
    [Show full text]
  • Forensic Materials Scientist Or “Whodunit” Detective
    S-E-A SEAlimited.com FALL 2019 FORENSIC MATERIALS SCIENTIST OR “WHODUNIT” DETECTIVE Being a forensic materials scientist is being a “whodunit” detective, tasked with determining why a product or process allegedly failed and who is responsible. Robert S. Carbonara, Ph.D. Forensic materials science is a broad devices (bolts, etc.), hoses and piping, Why the “so what” question matters technical discipline, that analyzes physical amusement rides, firearms, glassware, To illustrate the importance and practical evidence using the principles of physics and bicycles, CPVC piping, sprinkler systems, application of answering the “so what,” chemistry. Before the advent of modern storage tanks, and numerous others several complex case profiles are presented. engineering materials, most forensic • Material Production and Manufacturing These cases involved: (1) a serious injury materials scientists worked with metals and Processes — Recycling precious metal, where there was responsibility avoidance by were called metallurgists. Today, forensic aluminum and steel furnace operations, the parties involved, (2) a very complex metal materials scientists work with an metal casting operations, metal forging assortment of materials, including plastics, recovery process with a seven-figure loss and rolling production, pipe claim, (3) medical devices that fail and are ceramics, glass, composites, even wood and manufacturing leather and, of course, metals. Despite the complicated by issues of patient or doctor • Construction — Beams and support conduct, and (4) a pipeline failure that oc- broadening of the materials spectrum, the structures, welds, safety device material, same scientific principles that apply to metals curred many years after installation and with lifting cables, chains and straps, hoisting multiple possible technical failure scenarios.
    [Show full text]
  • Analysis of the Microstructure and Microhardness of Rotary Friction Welded Titanium (Ti‐6AL‐V4) Rods
    Analysis of the Microstructure and Microhardness of Rotary Friction Welded Titanium (Ti‐6AL‐V4) Rods DM Mukhawanaa, PM Mashininib and DM Madyirac aUniversity of Johannesburg, Department of Mechanical and Industrial Engineering Technology, Doornfontein Campus, Cnr Siemert & Beit Streets, Doornfontein, 2094 bUniversity of Johannesburg, Department of Mechanical and Industrial Engineering Technology, Doornfontein Campus, Cnr Siemert & Beit Streets, Doornfontein, 2094 cUniversity of Johannesburg, Department of Mechanical Engineering Science, Auckland Park Campus, Cnr Kingsway and University Road, Auckland Park, 2092 email address :[email protected], [email protected], [email protected] Abstract This paper presents the evolution of mechanical properties in Ti6Al4V rods welded by rotary friction welding. This is evaluated by monitoring the microstructure and micro hardness changes resulting from the welding. 16 mm diameter Ti6Al4V rods were joined by rotary friction welding utilizing different process parameter settings, namely; axial force, rotational speed and upset distance. The microstructure and micro hardness analysis were observed on each of the weld zones/regions. The micro hardness results revealed higher hardness on the weld zone and low hardness on the heat‐affected zone when compared to the parent material. The higher axial force resulted in higher hardness in the weld zone because of more friction and hence higher heat input which led to refined microstructure. Microstructure characterization for the different weld zones due to varying process parameters is also discussed. Keywords: Rotary friction welding, Ti‐6Al‐4V, Process parameters, Microstructure, Microhardness 1. Introduction Rotary Friction Welding (RFW) is a solid state welding process which uses frictional heat combined with pressure to join two components.
    [Show full text]
  • Microstructure and Mechanical Behaviuor of Rotary Friction Welded Titanium Alloys
    World Academy of Science, Engineering and Technology International Journal of Materials and Metallurgical Engineering Vol:1, No:11, 2007 Microstructure and Mechanical Behaviuor of Rotary Friction Welded Titanium Alloys M. Avinash, G. V. K. Chaitanya, Dhananjay Kumar Giri, Sarala Upadhya, and B. K. Muralidhara rotated part by sliding action under predetermined friction Abstract—Ti-6Al-4V alloy has demonstrated a high strength to pressure. The friction pressure is applied for a certain length weight ratio as well as good properties at high temperature. The of time. Then the drive is released and the rotary component is successful application of the alloy in some important areas depends quickly stopped while the axial pressure is being increased to on suitable joining techniques. Friction welding has many a higher predetermined upset pressure, for a predetermined advantageous features to be chosen for joining Titanium alloys. The time. The parts burn off to a few mm after the joint is made. A present work investigates the feasibility of producing similar metal simple set up of a rotary friction welding machine are shown joints of this Titanium alloy by rotary friction welding method. The joints are produced at three different speeds and the performances of in Fig. 1. the welded joints are evaluated by conducting microstructure studies, Friction welding has been successfully carried out by many Vickers Hardness and tensile tests at the joints. It is found that the workers earlier for producing both similar and dissimilar weld joints produced are sound and the ductile fractures in the tensile metal joints [3] - [9]. weld specimens occur at locations away from the welded joints.
    [Show full text]
  • Microstructure, Hardness, and Elastic Modulus of a Multibeam-Sputtered Nanocrystalline Co-Cr-Fe-Ni Compositional Complex Alloy Film
    materials Article Microstructure, Hardness, and Elastic Modulus of a Multibeam-Sputtered Nanocrystalline Co-Cr-Fe-Ni Compositional Complex Alloy Film Péter Nagy 1,2, Nadia Rohbeck 2, Zoltán Heged ˝us 3 , Johann Michler 2,László Pethö 2,János L. Lábár 1,4 and Jen˝oGubicza 1,* 1 Department of Materials Physics, Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary; [email protected] (P.N.); [email protected] (J.L.L.) 2 EMPA Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Mechanics of Materials and Nanostructures, Feuerwerkerstrasse 39, CH-3602 Thun, Switzerland; [email protected] (N.R.); [email protected] (J.M.); [email protected] (L.P.) 3 Deutsche Elektronen-Synchrotron DESY, Notkestr. 85, 22603 Hamburg, Germany; [email protected] 4 Institute for Technical Physics and Materials Science, Centre for Energy Research, Konkoly Thege Miklós út 29-33, H-1121 Budapest, Hungary * Correspondence: [email protected]; Tel.: + 36-1-372-2876; Fax: +36-1-372-2811 Abstract: A nanocrystalline Co-Cr-Ni-Fe compositional complex alloy (CCA) film with a thickness of about 1 micron was produced by a multiple-beam-sputtering physical vapor deposition (PVD) technique. The main advantage of this novel method is that it does not require alloy targets, but rather uses commercially pure metal sources. Another benefit of the application of this technique is that it produces compositional gradient samples on a disk surface with a wide range of elemental Citation: Nagy, P.; Rohbeck, N.; concentrations, enabling combinatorial analysis of CCA films. In this study, the variation of the Heged˝us,Z.; Michler, J.; Pethö, L.; phase composition, the microstructure (crystallite size and defect density), and the mechanical Lábár, J.L.; Gubicza, J.
    [Show full text]
  • Effect of Heterogeneous Microstructure on Refining Austenite Grain Size in Low Alloy Heavy-Gage Plate
    metals Article Effect of Heterogeneous Microstructure on Refining Austenite Grain Size in Low Alloy Heavy-Gage Plate Shengfu Yuan 1, Zhenjia Xie 2 , Jingliang Wang 2, Longhao Zhu 3, Ling Yan 3, Chengjia Shang 2,3,* and R. D. K. Misra 4 1 School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China; [email protected] 2 Colarborative Innovation Center of Steel Technology, University of Science and Technology Beijing, Beijing 100083, China; [email protected] (Z.X.); [email protected] (J.W.) 3 State Key Laboratory of Steel for Marina Equipment and Application, Anshan Steel, Anshan 114021, China; [email protected] (L.Z.); [email protected] (L.Y.) 4 Laboratory for Excellence in Advanced Steel Research, Department of Metallurgical and Materials Engineering, University of Texas at El Paso, El Paso, TX 79912, USA; [email protected] * Correspondence: [email protected]; Fax: +8610-6233-2428 Received: 18 November 2019; Accepted: 13 January 2020; Published: 16 January 2020 Abstract: The present work introduces the role of heterogeneous microstructure in enhancing the nucleation density of reversed austenite. It was found that the novel pre-annealing produced a heterogeneous microstructure consisting of alloying elements-enriched martensite and alloying-depleted intercritical ferrite. The shape of the martensite at the prior austenite grain boundary was equiaxed and acicular at inter-laths. The equiaxed reversed austenite had a K-S orientation with adjacent prior austenite grain, and effectively refined the prior austenite grain that it grew into. The alloying elements-enriched martensite provided additional nucleation sites to form equiaxed reversed austenite at both prior austenite grain boundaries and intragranular inter-lath boundaries during re-austenitization.
    [Show full text]