Material-science-kakani-2004 PDF

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This page intentionally left blank Copyright © 2004, New Age International (P) Ltd., Publishers Published by New Age International (P) Ltd., Publishers All rights reserved. No part of this ebook may be reproduced in any form, by photostat, microfilm, xerography, or any other means, or incorporated ...

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Copyright © 2004, New Age International (P) Ltd., Publishers Published by New Age International (P) Ltd., Publishers All rights reserved. No part of this ebook may be reproduced in any form, by photostat, microfilm, xerography, or any other means, or incorporated into any information retrieval system, electronic or mechanical, without the written permission of the publisher. All inquiries should be emailed to [email protected]

ISBN (13) : 978-81-224-2656-4

PUBLISHING FOR ONE WORLD

NEW AGE INTERNATIONAL (P) LIMITED, PUBLISHERS 4835/24, Ansari Road, Daryaganj, New Delhi - 110002 Visit us at www.newagepublishers.com

Preface Material Science has become a very important subject as an interdisciplinary course in almost all universities. Keeping this in view we have developed the subject matter for B.E. (Material Science and Metallurgy/Production Engineering/Mechanical Engineering), A.M.I.E., Diploma in engineering, M.Sc. (Material Science/Physics/Chemistry) and B.Sc. (Hons.) courses as per their latest syllabii. The book is also useful for UPSC, GATE, NET, SLET and other entrance examinations. A reasonably wide coverage in sufficient depth has been attempted, giving the importance to the basic principles, essential theory and experimental details necessary for understanding the nature, properties and applications of materials. All efforts have been made to provide topics which are of great use to the readers, e.g. semiconductors, superconductors, polymers, composites, nanostructured materials, etc. Latest developments, e.g. quantum dots, spinotrics, MOSFET, Microelectronic circuits, MEMS, nanotechnology, etc. are also covered. To make the text more useful, good number of worked out problems, review questions, problems, shortquestion answers, typical objective questions, suggested readings are provided with each chapter. We are thankful to M/s New Age International (P) Limited Publishers, for their untiring efforts in bringing out the book with excellent printing and nice get up within the shortest possible time period. Suggestions for the improvement of the book are most welcome. Bhilwara February 2004

S.L. Kakani Amit Kakani

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Contents Preface

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1. Classification and Selection of Materials 1. Introduction 1 2. Engineering Requirements 2 3. Classification of Engineering Materials 5 4. Organic, Inorganic and Biological Materials 7 5. Semiconductors 9 6. Biomaterials 10 7. (a) Current Trends and Advances in Materials 10 7. (b) Advanced Materials 10 7. (c) Smart Materials (Materials of the future) 11 7. (d) Nanostructured Materials and Nanotechnology 12 7. (e) Quantum Dots (QDs) 12 7. (f) Spintronics 12 7. (g) Fermionic Condensate Matter 13 8. Level of Material Structure Examination and Observation 9. Material Structure 13 10. Engineering Metallurgy 14 11. Selection of Materials 14 Suggested Readings 17 Review Questions 17 Problems 18 Short Question-Answers 18 Objective Questions 19

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2. Atomic Structure, and Electronic Configuration 1. Introduction 20 2. The Electron 20 3. Protons 21 4. Neutrons 21 5. Atomic Number (Z) 22 6. Atomic Weight and Mass Number 22 7. Isotopes 23 8. Isobars 23 9. Isotones 23 10. Avogadro’s Number (N) 24

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11. 12. 13. 14. 15. 16. 17.

Atomic Nucleus 24 Atomic Models 24 Vector Atom Model 43 Quantum Numbers 44 Pauli Exclusion Principle and Electronic Configuration of Atoms Wave Mechanical Picture of the Atom 54 Periodic Table 56 Suggested Readings 59 Review Questions 59 Problems 60 Short Questions 61 Objective Questions 61 Short Question-Answers 63

3. Crystal Geometry, Structure and Defects 1. Introduction 64 2. Crystals 65 3. Single Crystal 65 4. Whiskers 65 5. Lattice Points and Space Lattice 66 5. (a) Basis 66 6. Unit Cell 67 7. Primitive Cell 67 8. Crystal Classes 68 9. Crystal Systems 69 10. Crystal Structure for Metallic Elements 75 11. Atomic Radius 78 12. Density of Crystal 79 13. Directions, Lattice Planes and Miller Indices 80 14. Interplanar Spacings 83 14. (a) Angle Between Two Planes or Directions 84 15. Representation of Crystal Planes in a Cubic Unit Cell 84 16. Sketching the Plane from the given Miller Indices 86 17. Common Planes in a Simple Cubic Structure 86 18. Co-ordination Number 87 19. Defects or Imperfections in Crystals 95 20. Point Imperfections 96 21. Line Defects or Dislocations 98 22. Surface and Grain Boundary Defects 101 23. Volume Imperfections 104 24. Liquid Crystals 104 25. Anisotropy 105 26. Frank-Read Source 106 27. Theory of Dislocations: Salient Features 107 28. Determination of Crystal Structure by X-Ray Diffraction 110 29. Bragg’s X-ray Spectrometer 112 30. Reciprocal Lattice 115 31. Methods of Determining Crystal Structure 118 32. Electron and Neutron Diffraction 121

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33. Crystal Growth 122 Suggested Readings 123 Review Questions 123 Problems 124 Objective Questions 125 Short Questions Answers 127 4. Bonds in Solids 1. Introduction 129 2. Types of Bonds 129 3. Forces Between Atoms: Mechanism of Bond Formation and Bond Energy 131 4. Ionic Bonding 134 5. Covalent Bond 140 6. Metallic Bond 142 7. Comparison of Ionic, Covalent and Metallic Bonds 144 8. Secondary Bonds 145 9. Mixed Bonds (More About Secondary Bonds) 147 10. Properties of Solid Materials 148 11. Periodic Table and Chemical Bonding: Electronegativity 150 Suggested Readings 151 Review Questions 151 Problems 152 Objective Questions 153 Short Question Answers 154

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5. Electron Theory of Metals 1. Introduction 155 2. Metallic Bonding 155 3. Drude-Lorentz Theory 156 4. Sommerfield Free-Electron Theory 156 5. Fermi-Dirac Distribution Function (Electron Energies in a Metal) 159 6. Band Theory of Solids 160 7. Brillouin Zones 162 8. Distinction between Conductors, Insulators and Semiconductors 163 9. Electrical Resistance of Materials 164 10. Energy Bands 165 11. Equation of Motion of an Electron 166 12. Resistivity and Conductivity 167 13. Current Density in Metal 167 14. Mobility 168 15. Mean Free Path 171 16. Thermoelectricity 173 17. Origin of the Thermoelectric Effect 174 18. Magnitude and Direction of Thermo E.M.F. 174 19. Uses of Thermocouples 175 Suggested Readings 175 Review Questions 176 Problems 176 Objective Questions 176 Short Question Answers 177

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6. Photoelectric Effect 1. Introduction 179 2. Experimental Arrangement to Study the Photo Electric Effect 179 3. Failure of Classical Theory 182 4. Einstein’s Photoelectric Equation 183 5. Millikan’s Verification of Einstein’s Equation 184 6. Photoelectric Cells 186 7. Uses of photoelectric Cells 191 Suggested Readings 194 Review Questions 194 Problems 194 Objective Questions 195 Short Question-Answers 196

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7. Diffusion in Solids 1. Introduction 197 2. Types of Diffusion 197 3. Diffusion Mechanisms 197 4. Diffusion Coefficient: Fick’s Laws of Diffusion 199 5. Dependence of Diffusion Coefficient on Temperature 202 6. Factors Affecting Diffusion Coefficient (D) 202 7. Self Diffusion 203 8. Inter-Diffusion 203 9. Experimental Determination of D using a Diffusion Couple 203 10. Diffusion with Constant Concentration (Case Hardening) 204 11. The Kirkendall Effect 204 12. Diffusion in Oxides and Ionic Crystals 205 13. Surface Diffusion 205 14. Activation Energy of Diffusion 205 15. Applications of Diffusion 206 Suggested Readings 210 Review Questions 210 Problems 211 Objective Questions 211 Short Question-Answers 212

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8. Mechanical Properties of Materials and Mechanical Tests 1. Introduction 213 2. Common Terms 214 3. Atomic Model of Elastic Behaviour 226 4. Modulus (Y ) as a Parameter of Design 227 5. Fundamental Mechanical Properties 228 Stress-Rupture Test 243 6. Factors affecting Mechanical Properties 244 7. Mechanical Tests 246 8. Non-Destructive Testing (NDT) 258 9. Fracture 260 Suggested Readings 272 Review Questions 272 Problems 274

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Objective Questions 274 Short Question-Answers 276 9. Alloy Systems, Phase Diagrams and Phase Transformations 1. Introduction 279 2. Alloy Systems 280 3. Solid Solutions 281 4. The Families of Engineering Alloys 283 5. Hume-Rothery’s Rules 285 6. Intermediate Phases or Intermediate Compounds (or Intermediate Solid Solutions) 7. Phase Diagrams 286 8. The Phase Rule or Gibb’s Phase Rule or Condensed Phase Rule 287 9. Cooling Curves (Time-Temperature Curves) 288 10. Construction of a Phase Diagram or Constitutional Diagram 289 11. The Lever Rule 290 12. Equilibrium Diagrams for Binary Alloys Forming Eutectic 292 13. Ceramic and Ternary phase Diagrams 294 14. Applications of Phase Diagrams 295 15. Coring 295 16. Phase Transformations 296 17. The Kinetics of Solid State Reactions 296 18. Multiphase Transformations 300 19. Applications of Phase Transformations 300 20. Micro-constituents of Fe-C System 302 21. Allotropic forms of Iron 304 21. Iron-carbon System 305 22. Iron-carbon equilibrium or Phase Diagram 305 23. Modified Iron-carbon Phase Diagram 306 24. Formation and Decomposition of Austenite 309 25. Types and Properties of Carbon-Steels 311 26. Isothermal Transformations-TTT Diagram 312 27. Transformation of Austenite upon Continuous Cooling 314 28. Transformation of Austenite to Martensite 315 29. Metals for Nuclear Energy 316 Suggested Readings 318 Review Questions 318 Problems 319 Short Question Answers 319 Objective Questions 320 10. Heat Treatment 1. Introduction 321 2. Heat-Treatment Processes 322 3. Annealing 322 4. Annealing Operations 323 5. Mass Effect 336 6. Principal Equipment for Heat Treatment 336 7. Major Defects in Metals or Alloys due to Faulty Heat Treatment 8. Surface Finish After Heat Treatment 339 9. Measurement of High Temperatures and Pyrometers 340

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Suggested Readings 344 Review Questions 344 Problems 345 Short Question-Answers 346 Objective Questions 346 11. Deformation of Materials 1. Introduction 348 2. Elastic Deformation 348 3. Plastic Deformation 349 4. Deformation by Twinning 355 5. Comparison between Slip and Twinning 356 6. Plastic Deformation of Polycrystalline Materials 357 7. Work Hardening or Strain Hardening 357 8. Season Cracking 359 9. Bauschinger Effect 359 10. Anelasticity 359 11. Adiabatic and Isothermal Straining 360 12. Yield Point Phenomenon and Related Effects 361 13. Atomic Diffusion–An Elastic After Effect 363 14. Preferred Orientation 364 15. Recovery, Recrystallization and Grain Growth 365 16. Hot-Working 368 Suggested Readings 371 Review Questions 371 Problems 372 Objective Questions 373 Short Question Answers 373

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12. Oxidation and Corrosion 1. Introduction 375 2. Corrosion-resistant Materials 375 3. Electrochemical Corrosion 375 4. Galvanic (Two-Metal) Corrosion 380 5. Corrosion Rates 381 6. High Temperature Oxidation or Dry Corrosion 382 7. Passivity 382 8. Environmental Effects 383 9. Specific Forms of Corrosion 383 10. Corrosion Prevention and Control 388 11. Corrosion Monitoring and Management 394 Suggested Readings 396 Review Questions 396 Problems 397 Short Question-Answers 397 Objective Questions 398

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13. Thermal and Optical Properties of Materials Section A: Thermal Properties 400 1. Introduction 400

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2. Heat Capacity 400 3. Theoretical Models 403 4. Thermal Expansion 406 5. Thermal Conductivity (K) 409 6. Refractories 414 7. Thermal Stresses 415 8. Thermal Fatigue 416 9. Thermal Shock 416 10. Melting Point (M.P.) 416 Section B: Optical Properties 418 1. Optical Properties 418 2. Interactions of Light with Solids 418 3. Atomic and Electronic Interactions 418 4. Optical Properties of Metals 419 5. Optical Properties of Non metals 420 6. Applications of Optical Phenomena 424 Suggested Readings 426 Review Questions 427 Problems 428 Objective Questions 428 Short Question-Answers 430 14. Electrical and Magnetic Properties of Materials 1. Introduction 431 2. Electrical Conduction 431 3. Electrical Conductivity (I) 433 4. Electronic and Ionic Conduction 435 5. Band Structure in Solids 435 6. Conduction in Terms of Band and Atomic Bonding Models 438 7. Electrical Resistivity of Metals 440 8. Electrical Characteristics of Alloys Used for Commercial Purposes 442 9. Mechanisms of Strengthening in Metals 442 10. Insulators 443 11. Dielectrics 445 12. Magnetism 456 Suggested Readings 480 Review Questions 480 Problems 482 Objective Questions 483 Short Question Answers 484

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15. Semiconductors 1. Introduction 488 2. Intrinsic Semiconductors 489 3. Extrinsic Semiconductors 494 4. Semiconductor Devices 500 5. The Transistor 514 6. Semiconductors in Computers 518 7. Microelectronic Circuits 518 8. Microelectromechanical Systems (MEMS)

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9. Quantum Dots (QDs) 520 10. Spintronics 520 Suggested Readings 522 Review Questions 523 Problems 523 Objective Questions 524 Short Question Answers 525 16. Superconductivity and Superconducting Materials 1. Introduction 526 2. Superconducting Materials 529 3. HTSC Cuprate Materials Characteristics 532 4. Characteristic Properties of Superconductors 535 5. Josephson Effects 540 6. Properties of HTSC Oxides 541 7. Thermodynamics of a Superconductor 542 8. Theory of Superconductivity 544 9. Quantum Tunneling 547 10. Applications of Superconductivity 548 Suggested Readings 551 Review Questions 551 Short Questions 552 Problems 552 Objective Questions 553 Short Question Answers 553

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17. Organic Materials: Polymers and Elastomers 1. Introduction 555 2. Polymers 555 3. Broad Classifications 558 4. Basic Concepts of Polymer Science 559 5. Molecular Configurations 567 6. Thermoplastic and Thermosetting Polymers 568 7. Copolymers 568 8. Polymer Crystallinity 569 9. Defects in Polymers 570 10. Mechanical Properties of Polymers 570 11. Mechanisms of Deformation 572 12. Crystallization, Melting and Glass Transition Phenomena in Polymers 13. Polymer Types 573 14. Miscellaneous Applications of Polymers 578 15. Advanced Polymeric Materials 579 16. Polymer Additives 580 17. Manufacturing Processes Involving Polymers 582 18. Reinforced Polymers 584 19. Behaviour of Polymers 585 20. Fabrication of Fibres and Films 586 21. Wood 587 Suggested Readings 588 Review Questions 589

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Problems 590 Objective Questions 590 Short Questions Answers 591 18. Composites 1. Introduction 593 2. General Characteristics 594 3. Particle-Reinforced Composites 596 4. Fibre-Reinforces Composites 598 5. Fabrication 609 Suggested Readings 611 Review Questions 611 Problems 611 Objective Questions 612 Short Question Answers 612

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19. Nanostructured Materials 1. Introduction 614 2. Production Methods for CNTs 621 3. Key Issues in Nanomanufacturing 624 4. Mechanical and Electronic Properties of Carbon Nanotubes 624 5. Nanostructures in Motion 624 6. Nanomaterial Advantage 624 Suggested Readings 626 Review Questions 626 Appendix 1: Units, Conversion Factors, Physical Constants 627 Units 627 Appendix 2: Conversion Factors 630 Appendix 3: Physical Constants 632 Appendix 4: Prefix Names, Symbols and Multiplication Factors 633

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Subject Index

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1 Classification and Selection of Materials 1. INTRODUCTION Materials science and engineering plays a vital role in this modern age of science and technology. Various kinds of materials are used in industry, housing, agriculture, transportation, etc. to meet the plant and individual requirements. The rapid developments in the field of quantum theory of solids have opened vast opportunities for better understanding and utilization of various materials. The spectacular success in the field of space is primarily due to the rapid advances in high-temperature and high-strength materials. The selection of a specific material for a particular use is a very complex process. However, one can simplify the choice if the details about (i) operating parameters, (ii) manufacturing processes, (iii) functional requirements and (iv) cost considerations are known. Factors affecting the selection of materials are summarized in Table 1.1. Table 1.1 Factors affecting selection of materials (i) Manufacturing processes l l l l l l l l l

Plasticity Malleability Ductility Machinability Casting properties Weldability Heat Tooling Surface finish

(ii) Functional requirements l l l l l l l l l

Strength Hardness Rigidity Toughness Thermal conductivity Fatigue Electrical treatment Creep Aesthetic look

(iii) Cost considerations l l l l l l l l l

Raw material Processing Storage Manpower Special treatment Inspection Packaging properties Inventory Taxes and custom duty

(iv) Operating parameters l l l l l l l l l

Pressure Temperature Flow Type of material Corrosion requirements Environment Protection from fire Weathering Biological effects

There are thousands and thousands of materials available and it is very difficult for an engineer to possess a detailed knowledge of all the materials. However, a good grasp of the fundamental principles which control the properties of various materials help one to make the optimum selection of material. In this respect, materials science and engineering draw heavily from the engineering branches, e.g. metallurgy, ceramics and polymer science. The subject of material science is very vast and unlimited. Broadly speaking, one can sub-divide the field of study into following four branches: (i) Science of metals, (ii) Mechanical behaviour of metals (iii) Engineering metallurgy and (iv) Engineering materials. We shall discuss them in subsequent chapters.

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2. ENGINEERING REQUIREMENTS While selecting materials for engineering purposes, properties such as impact strength, tensile strength, hardness indicate the suitability for selection but the design engineer will have to make sure that the radiography and other properties of the material are as per the specifications. One can dictate the method of production of the component, service life, cost etc. However, due to the varied demands made metallic materials, one may require special surface treatment, e.g. hardening, normalising to cope with the service requires. Besides, chemical properties of materials, e.g. structure, bonding energy, resistance to environmental degradation also effect the selection of materials for engineering purposes. In recent years polymeric materials or plastics have gained considerable popularity as engineering materials. Though inferior to most metallic materials in strength and temperature resistance, these are being used not only in corrosive environment but also in the places where minimum wear is required, e.g. small gear wheels, originally produced from hardened steels, are now manufactured from nylon or teflon. These materials perform satisfactorily, are quiet and do not require lubrication. Thus, before selecting a material or designing a component, it is essential for one to understand the requirements of the process thoroughly, operating limitations like hazardous or non-hazardous conditions, continuous or non-continuous operation, availability of raw materials as well as spares, availability of alternate materials vis-a-vis life span of the instrument/equipment, cost etc. Different materials possess different properties to meet the various requirement for engineering purposes. The properties of materials which dictate the selection are as follows: (a) Mechanical Properties The important mechanical properties affecting the selection of a material are: ...