1.MATERIALS SCIENCEMATERIALS SCIENCE && METTALURGYMETTALURGY Dr. Achchhe Lal Department of Mechanical Engineering SVNIT Surat-395007 Phone: (+91) (261) 2201993, Mobile: 9824442503 Email: lalachchhe@yahoo.co.in, URL: http://www.svnit.ac.inKindly send your comments and feedback for improvement at this email address Projectcoordination

2. Basic References Materials Science and Engineering (5th Edition) V. Raghavan Prentice-Hall of India Pvt. Ltd., 2004. Callister's Materials Science and Engienering William D Callister (Adapted by R. Balasubramaniam) Wiley Inida (P) Ltd., 2007. The Science and Engineering of Materials Donald. R. Askeland & Pradeep Phul Cengage Learning, 2006. 3. Introduction to diverse kinds of engineering materials Overview of what determines the properties of materials and how we engineer them Structure of materials and various lengthscales: crystal structure, electromagnetic structure, defect structure, microstructure Stability and metastability of materials: the thermodynamics and kinetics The tools used in materials science: x-ray diffraction, phase diagrams, TTT diagrams Properties of materials: elasticity, plasticity, fracture, fatigue, creep, conduction, magnetism What will you learn?What will you learn? A teachers job is to uncover and not cover the syllabus- Richard M Felder 4. The following hyperlinks are to file-wise substructure. Content-wise substructure will appear in respective chapters.The following hyperlinks are to file-wise substructure. Content-wise substructure will appear in respective chapters. 1. CHAPTER 1: Introduction 1.1 Introduction to Materials 1.2 Hierarchy of Lengths scales 1. CHAPTER 1: Introduction 1.1 Introduction to Materials 1.2 Hierarchy of Lengths scales CHAPTER 2: CLASSIFICATION OF MATERIALS AND METALS Semiconductor, magnetic dielectric, Superconductor, nanomaterials, engineering alloy and steel , cost Irons and nonferrous materials CHAPTER 2: CLASSIFICATION OF MATERIALS AND METALS Semiconductor, magnetic dielectric, Superconductor, nanomaterials, engineering alloy and steel , cost Irons and nonferrous materials 3. CHAPTER 3: POLYMERS, CERAMICS & COMPOSITES Definition, Classification & characteristics of polymers, Types of polymerization, Polymer processing, Elastomers, Properties of ceramic materials, Cermets, Composite mate rials, Fiber reinforced plastic (FRP) 3. CHAPTER 3: POLYMERS, CERAMICS & COMPOSITES Definition, Classification & characteristics of polymers, Types of polymerization, Polymer processing, Elastomers, Properties of ceramic materials, Cermets, Composite mate rials, Fiber reinforced plastic (FRP) 4. CHAPTER 4: PHASE DIAGRAM Objectives & classification, System, phases & structural constituent of phase diagram, Coring & dendritic segregation, Gibbs, solid phase rule, Eutectic, Peritectic & eutec toid system, Equilibrium diagrams for non - ferrous alloys, Lever rule. 4. CHAPTER 4: PHASE DIAGRAM Objectives & classification, System, phases & structural constituent of phase diagram, Coring & dendritic segregation, Gibbs, solid phase rule, Eutectic, Peritectic & eutec toid system, Equilibrium diagrams for non - ferrous alloys, Lever rule. 5. CHAPTER 5: HEAT TREATMENT PROCESSES Definition, Purpose & classification of heat treatment processes for various types of special steels, Introduction & applications of various case hardening & surface hardening treatments. TTT & CCT curves 5. CHAPTER 5: HEAT TREATMENT PROCESSES Definition, Purpose & classification of heat treatment processes for various types of special steels, Introduction & applications of various case hardening & surface hardening treatments. TTT & CCT curves 6. CHAPTER 6: MECHANICAL BEHAVIOR OF METALS properties of metals, Deformation of metals, Mechanisms of deformation, Deformation in polycrystalline materials, Mechanical testing of materials (destructive & non -destructive testing methods). 6. CHAPTER 6: MECHANICAL BEHAVIOR OF METALS properties of metals, Deformation of metals, Mechanisms of deformation, Deformation in polycrystalline materials, Mechanical testing of materials (destructive & non -destructive testing methods). 5. 5 Objectives of Chapter 1 Introduce the field of materials science and engineering (MSE) Provide introduction to the classification of materials 6. 6 Chapter Outline 1.1 What is Materials Science and Engineering? 1.2 Classification of Materials 1.3 Functional Classification of Materials 1.4 Classification of Materials Based on Structure 1.5 Environmental and Other Effects 1.6 Materials Design and Selection 7. Introduction to Materials Science Material Science: Science of materials means knowledge of material which help the engineers and technologist to make best and efficient use of material to serve need of modern civilization. In Short: Material science doesnt mean just knowing the physics and chemistry of the material, their behavior and properties, but also it is essential to know how material can be suitably, efficiently and economically put to the practical use under wide range of conditions. The conditions may be related to the operation, to the fabrication and/or to the stability to the materials in order to develop, prepare modify and apply material to specific need. Materials are available in solid, liquid and gaseous form. However the scope of materials are restricted to the study of solid materials those are useful to the to the engineering. 8. Four Major Components of Material Science and Engineering: Structure of Materials Properties of Materials Processing of Materials Performance of Materials The ability to understand the relationships between these factors has been crucial to most of mankinds technological breakthroughs. 9. 9 2003 Brooks/Cole Publishing / Thomson Learning Introduction to Chapter 1 10. 10 2003Brooks/ColePublishing/ThomsonLearning Figure 1.1 Application of the tetrahedron of materials science and engineering to ceramic superconductors. Note that the microstructure- synthesis and processing-composition are all interconnected and affect the performance-to-cost ratio 11. 11 Figure 1.2 Application of the tetrahedron of materials science and engineering to sheet steels for automotive chassis. Note that the microstructure-synthesis and processing-composition are all interconnected and affect the performance-to- cost ratio 2003Brooks/ColePublishing/ThomsonLearning 12. 12 2003Brooks/ColePublishing/ThomsonLearning Figure 1.3 Application of the tetrahedron of materials science and engineering to semiconducting polymers for microelectronics 13. 6 Ao Ad force die blank force Forging (wrenches, crankshafts) CASTING JOININGFORMING Drawing (rods, wire, tubing) often at elev. T Rolling (I-beams, rails) Extrusion (rods, tubing) Adapted from Fig. 11.7, Callister 6e. ram billet container container force die holder die Ao Adextrusion roll Ao Ad roll tensile force Ao Addie die METAL FABRICATION METHODS-I 14. plaster die formed around wax prototype FORMING JOINING 8 CASTING Sand Casting (large parts, e.g., auto engine blocks) Sand Sand molten metal Investment Casting (low volume, complex shapes e.g., jewelry, turbine blades) wax Die Casting (high volume, low T alloys) Continuous Casting (simple slab shapes) molten solidified METAL FABRICATION METHODS-II 15. 7 Hot working --recrystallization --less energy to deform --oxidation: poor finish --lower strength Cold working --more energy to deform --oxidation: good finish --higher strength Cold worked microstructures --generally are very anisotropic! --Forged --Fracture resistant! (a) (b) (c) --Swaged FORMING TEMPERATURE 16. 9 CASTINGFORMING JOINING Powder Processing (materials w/low ductility) pressure heat point contact at low T densification by diffusion at higher T area contact densify Welding (when one large part is impractical) Heat affected zone: (region in which the microstructure has been changed). Adapted from Fig. 11.8, Callister 6e. (Fig. 11.8 from Iron Castings Handbook, C.F. Walton and T.J. Opar (Ed.), 1981.) piece 1 piece 2 fused base metal filler metal (melted) base metal (melted) unaffectedunaffected heat affected zone METAL FABRICATION METHODS-III 17. 10 Annealing: Heat to Tanneal, then cool slowly. Types of Annealing Process Anneal: Negate effect of cold working by (recovery/ recrystallization) Stress Relief: Reduce stress caused by: -plastic deformation -nonuniform cooling -phase transform. Normalize (steels): Deform steel with large grains, then normalize to make grains small. Full Anneal (steels): Make soft steels for good forming by heating to get , then cool in furnace to get coarse P. Spheroidize (steels): Make very soft steels for good machining. Heat just below TE & hold for 15-25h. Based on discussion in Section 11.7, Callister 6e. THERMAL PROCESSING OF METALS 18. 11 Ability to form martensite Jominy end quench test to measure hardenability. Hardness versus distance from the quenched end. 24C water specimen (heated to phase field) flat ground 4 1 Hardness,HRC Distance from quenched end Adapted from Fig. 11.10, Callister 6e. (Fig. 11.10 adapted from A.G. Guy, Essentials of Materials Science, McGraw-Hill Book Company, New York, 1978.) Adapted from Fig. 11.11, Callister 6e. HARDENABILITY--STEELS 19. Metals Nonmetals Ceramic Polymer Materials Composite Classification of Materials Ferrous metals Non ferrous metals Magnetic Materials Semiconductor Superconductor dielectric Bio Materials Future Materials Smart Materials Nanomaterial Steel CI PCS Alloy 20. Monolithic MaterialsMaterials Hybrids Ceramics & Glasses Metals (& Alloys) Polymers (& Elastomers) Sandwich Composite Lattice Segment Composites: have two (or more) solid components; usually one is a matrix and other is a reinforcement Sandwich structures: have a material on the surface (one or more sides) of a core material Lattice* Structures: typically a combination of material and space (e.g. metallic or ceramic forms, aerogels etc.). Segmented Structures: are divided in 1D, 2D or 3D (may consist of one or more materials). *Note: this use of the word 'lattice' should not be confused with the use of the word in connection with crystallography. Hybrids are designed to improve certain properties of monolithic materials 21. Common type of materials Metals Ceramics Polymers Hybrids (Composites) Let us consider the common types of Engineering Materials. These are Metals, Ceramics, Polymers and various types of composites of these. A composite is a combination of two or more materials which gives a certain benefit to at least one property A comprehensive classification is given in the next slide. The term Hybrid is a superset of composites. The type of atomic entities (ion, molecule etc.) differ from one class to another, which in turn gives each class a broad flavour of properties. Like metals are usually ductile and ceramics are usually hard & brittle Polymers have a poor tolerance to heat, while ceramics can withstand high temperatures Metals are opaque (in bulk), while silicate glasses are transparent/translucent Metals are usually good conductors of heat and electricity, while ceramics are poor in this aspect. If you heat semi-conductors their electrical conductivity will increase, while for metals it will decrease Ceramics are more resistant to harsh environments as compared to Metals Biomaterials are a special class of materials which are compatible with the body of an organism (biocompatible). Certain metals, ceramics, polymers etc. can be used as biomaterials. A Common Perspective & Glasses Diamond is poor electrical conductor but a good thermal conductor!! (phonons are responsible for this) Bonding and structure are key fac 22. Common materials: with various viewpoints Glass: amorphous Ceramics Crystal Graphite PolymersMetals 23. Metals and alloys Cu, Ni, Fe, NiAl (intermetallic compound), Brass (Cu-Zn alloys) Ceramics (usually oxides, nitrides, carbides) Alumina (Al2O3), Zirconia (Zr2O3) Polymers (thermoplasts, thermosets) (Elastomers) Polythene, Polyvinyl chloride, Polypropylene Common materials: examples Based on Electrical Conduction Conductors Cu, Al, NiAl Semiconductors Ge, Si, GaAs Insulators Alumina, Polythene* Based on Ductility Ductile Metals, Alloys Brittle Ceramics, Inorganic Glasses, Ge, Si * some special polymers could be conducting 24. Based on state (phase) a given material can be Gas, Liquid or Solid (based on the thermodynamic variables: P, T,). Intermediate/coexistent states are also possible (i.e clear demarcations can get blurred). (Kinetic variables can also affect how a material behaves: e.g. at high strain rates some materials may behave as solids and as a liquid at low strain rates) Based on structure (arrangement of atoms/molecules/ions) materials can be Crystalline, Quasicrystalline or Amorphous. Intermediate states (say between crystalline and amorphous; i.e. partly crystalline) are also possible. Polymers are often only partly crystalline. Liquid Crystals (in some sense) are between Liquids and Crystals. Based on Band Structure we can classify materials into Metals, Semi-metals, Semiconductors and Insulators. Based on the size of the entity in question we can Nanocrystals, Nanoquasicrystals etc. 25. In the next two slides we will traverse across lengthscales to demarcate the usual domain of Materials Science. Many of the terms and concepts in the slide will be dealt with in later chapters As we shall see the scale of Microstructures is very important and in some sense Materials Scientists are also Microstructure Engineers! There could be issues involved at the scale of the component (i.e. design of the component or its meshing with the reminder of the system), which are traditionally not included in the domain of Materials Science. E.g. sharp corners in a component would lead to stress concentration during loading, which could lead to crack initiation and propagation, leading to failure of the component. The inherent resistance of the material to cracks (and stress concentrations) would typically be of concern to materials scientists and not the design of the component. 26. Atom Structure Crystal Electro- magnetic Microstructure Component Thermo-mechanical Treatments Phases Defects+ Casting Metal Forming Welding Powder Processing Machining Vacancies Dislocations Twins Stacking Faults Grain Boundaries Voids Cracks + Residual Stress Processing determines shape and microstructure of a component & their distribution Materials ScienceMaterials Science Please spend time over this figure and its implications (notes in the next slide) (Notes in the next slide) 27. Structure could imply two types of structure: Crystal structure Electromagnetic structure Fundamentally these aspects are two sides of the same coin Microstructure can be defined as: (Phases + Defect Structure + Residual Stress) and their distributions (more about these in later chapters) Microstructure can be tailored by thermo-mechanical treatments A typical component/device could be a hybrid with many materials and having multiple microstructures E.g. a pen cap can have plastic and metallic parts 28. What determines the properties of materials? Funda Check There are microstructure sensitive properties (often called structure sensitive properties) and microstructure insensitive properties (note the word is sensitive and not dependent). Microstructure sensitive properties Yield stress, hardness, Magnetic coercivity Microstructure insensitive properties Density, Elastic modulus Hence, one has to keep in focus: Atomic structure Electromagnetic structure/Bonding Microstructure to understand the properties. 29. MATERIALS SCIENCE & ENGINEERINGMATERIALS SCIENCE & ENGINEERING PHYSICAL MECHANICAL ELECTRO- CHEMICAL TECHNOLOGICAL Extractive Casting Metal Forming Welding Powder Metallurgy Machining Structure Physical Properties Science of Metallurgy Deformation Behaviour Thermodynamics Chemistry Corrosion The broad scientific and technological segments of Materials Science are shown in the diagram below. To gain a comprehensive understanding of materials science, all these aspects have to be studied. 30. What determines the properties of materials? 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! The presence of surface compressive stress toughens glass Composition Phases & Their Distribution Defect Structure Residual Stress Hence, one has to traverse across lengthscales and look at various aspects to understand the properties of materials The following factors put together determines the properties of a material: Composition Phases present and their distribution Defect Structure (in the phases and between the phases) Residual stress (can have multiple origins and one may have to travel across lengthscales) These factors do NOT act independent of one another (there is an interdependency) Click here to understand stressClick here to understand stress 31. Properties influenced by Atomic structure Electromagnetic structure (Bonding characteristics) Properties of a material are determined by two important characteristics: Atomic structure Electromagnetic structure the bonding character (Bonding in some sense is the simplified description of valence electron density distributions) 32. The goal of Materials Science and Engineering is to design materials with a certain set of properties, which gives a certain desired performance. Using suitable processing techniques the material can be synthesized and processed. The processing also determines the microstructure of the material. To understand the microstructure the material scientist has to traverse across lengthscales and has to comprehend the defect structure in the material along with the phases and their distribution. The residual stress state in the material is also very important. Common types of materials available to an engineer are: Metals, Ceramics and Polymers. A hybrid made out of these materials may serve certain engineering goals better. Materials are also classified based on Band Structure (Metals, Semi-metals, Semiconductors, Insulators) or Atomic Structure (Crystals, Quasicrystals, Amorphous phases). Summary 33. fundamental Materials Metals: Strong, ductile, toughness high thermal & electrical conductivity opaque, reflective. Examples: Iron/Steel, Aluminum, Copper, Titanium, Nickel Polymers/plastics: Covalent bonding sharing of es Soft, ductile, low strength, low density, less dense than metals or ceramics, resist atmospheric and other forms of corrosion thermal & electrical insulators Optically translucent or transparent. Examples: Plastics, Wood, Cotton (rayon, nylon), glue, polyethylene Types: Thermoplastics plastics (usually soft and melt when heated and easy to be recycled), Thermo-set plastics (usually stiff and burn when heated and not easy to be recycled), Elastomers (flexible (rubbers)) Ceramics: ionic bonding (refractory) compounds of metallic & non-metallic elements (oxides, carbides, nitrides, sulfides) Brittle, glassy, elastic, excellent strength and hardness properties non-conducting (insulators), more resistant to high temperatures Structural clay products, Whitewares, Refractories, Glasses, Cements 34. Fe3C cementite Metal Alloys Steels Ferrous Nonferrous Cast Irons Cu Al Mg Ti