Materials Science and Engineering: An Introduction PDF

 10th Edition Materials Science and Engineering AN INTRODUCTION WILLIAM D. CALLISTER, JR. Department of Metallurgical Engineering The University of Utah DAVID G. RETHWISCH Department...

 10th Edition Materials Science and Engineering AN INTRODUCTION WILLIAM D. CALLISTER, JR. Department of Metallurgical Engineering The University of Utah DAVID G. RETHWISCH Department of Chemical and Biochemical Engineering The University of Iowa Front Cover: Representation of a (110) plane for barium titanate (BaTiO3), which has the perovskite crystal structure. Red, purple, and green spheres represent, respectively, oxygen, barium, and titanium ions. Back Cover: Depiction of a (123) plane for sodium chloride (NaCl), which has the rock salt crystal structure. Green and brown spheres denote chlorine and sodium ions, respectively. VICE PRESIDENT AND DIRECTOR Laurie Rosatone ACQUISITIONS EDITOR Linda Ratts DEVELOPMENT EDITOR Adria Giattino EDITORIAL ASSISTANT Adriana Alecci MARKETING MANAGER John LaVacca SENIOR PRODUCT DESIGNER Tom Kulesa PRODUCTION EDITOR Ashley Patterson SENIOR CONTENT MANAGER Valerie Zaborski SENIOR PHOTO EDITOR MaryAnn Price COVER DESIGNER Tom Nery COVER ART Roy Wiemann and William D. Callister, Jr. This book was set in 9.5/11.5 Times Ten LT Std by Aptara, Inc., and printed and bound by Quad Graphics/Versailles. The cover was printed by Quad Graphics/Versailles. Founded in 1807, John Wiley & Sons, Inc. has been a valued source of knowledge and understanding for more than 200 years, helping people around the world meet their needs and fulfill their aspirations. Our company is built on a foundation of principles that include responsibility to the communities we serve and where we live and work. 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Upon completion of the review period, please return the evaluation copy to Wiley. Return instructions and a free of charge return shipping label are available at: www.wiley.com/go/returnlabel. If you have chosen to adopt this textbook for use in your course, please accept this book as your complimentary desk copy. Outside of the United States, please contact your local sales representative. The inside back cover will contain printing identification and country of origin if omitted from this page. In addition, if the ISBN on the back cover differs from the ISBN on this page, the one on the back cover is correct. Library of Congress Cataloging in Publication Data Names: Callister, William D., Jr., 1940- author. | Rethwisch, David G., author. Title: Materials science and engineering : an introduction / by William D. Callister, Department of Metallurgical Engineering, The University of Utah, David G. Rethwisch, Department of Chemical and Biochemical Engineering, The University of Iowa. Description: 10th edition. | Hoboken, NJ : Wiley, | Includes bibliographical references and index. | Identifiers: LCCN 2017029444 (print) | LCCN 2017032239 (ebook) | ISBN 9781119405498 (Enhanced epub) | ISBN 9781119405436 (pdf) | ISBN 9781119405399 (loose leaf print companion) | ISBN 9781119405405 (evalc (paper)) Subjects: LCSH: Materials. | Materials science—Textbooks. Classification: LCC TA403 (ebook) | LCC TA403.C23 2018 (print) | DDC 620.1/1—dc23 LC record available at https://lccn.loc.gov/2017029444 ISBN-13: 9781119321590 Printed in the United States of America 10 9 8 7 6 5 4 3 2 1  Dedicated to the memory of Peter Joseph Rethwisch Father, lumberman, and friend  Preface I n this tenth edition we have retained the objectives and approaches for teaching materials science and engineering that were presented in previous editions. These objec- tives are as follows: Present the basic fundamentals on a level appropriate for university/college students. Present the subject matter in a logical order, from the simple to the more complex. If a topic or concept is worth treating, then it is worth treating in sufficient detail and to the extent that students have the opportunity to fully understand it without having to consult other sources. Inclusion of features in the book that expedite the learning process, to include the following: photographs/illustrations; learning objectives; “Why Study...” and “Materials of Importance” items; “Concept Check” questions; questions and problems; Answers to Selected Problems; summary tables containing key equations and equation symbols; and a glossary (for easy reference). Employment of new instructional technologies to enhance the teaching and learning processes. New/Revised Content This new edition contains a number of new sections, as well as revisions/amplifications of other sections. These include the following: New discussions on the Materials Paradigm and Materials Selection (Ashby) Charts (Chapter 1) Revision of Design Example 8.1—“Materials Specification for a Pressurized Cylindrical Tank” (Chapter 8) New discussions on 3D printing (additive manufacturing)—Chapter 11 (metals), Chapter 13 (ceramics), and Chapter 15 (polymers) New discussions on biomaterials—Chapter 11 (metals), Chapter 13 (ceramics), and Chapter 15 (polymers) New section on polycrystalline diamond (Chapter 13) Revised discussion on the Hall effect (Chapter 18) Revised/expanded discussion on recycling issues in materials science and engineering (Chapter 22) All homework problems requiring computations have been refreshed BOOK VERSIONS There are three versions of this textbook as follows: Digital (for purchase)—formatted as print; contains entire content v vi Preface Digital (in WileyPLUS)—formatted by section; contains entire content Abridged Print (Companion)—binder ready form; problem statements omitted ONLINE RESOURCES Associated with the textbook are online learning resources, which are available to both students and instructors. These resources are found on three websites: (1) WileyPLUS, (2) a Student Companion Site, and (3) an Instructor Companion Site. WileyPLUS (www.wileyplus.com) WileyPLUS is a research-based online environment for effective teaching and learning. It builds students’ confidence by taking the guesswork out of studying by providing them with a clear roadmap: what is assigned, what is required for each assignment, and whether assign- ments are done correctly. Independent research has shown that students using WileyPLUS will take more initiative so the instructor has a greater impact on their achievement in the classroom and beyond. WileyPLUS also helps students study and progress at a pace that’s right for them. Our integrated resources–available 24/7–function like a personal tutor, di- rectly addressing each student’s demonstrated needs by providing specific problem-solving techniques. What do students receive with WileyPLUS? They can browse the following WileyPLUS resources by chapter. The Complete Digital Textbook (at a savings up to 60% of the cost of the in-print text). Each chapter is organized and accessed by section (and end-of-chapter elements). (Found under Read, Study & Practice/CONTENTS/Select Chapter Number/CHAPTER RESOURCES/Reading Content.) Virtual Materials Science and Engineering (VMSE). This web-based software package consists of interactive simulations and animations that enhance the learning of key concepts in materials science and engineering. Included in VMSE are eight modules and a materials properties/cost database. Titles of these modules are as follows: (1) Metallic Crystal Structures and Crystallography; (2) Ceramic Crystal Structures; (3) Repeat Unit and Polymer Structures; (4) Dislocations; (5) Phase Diagrams; (6) Diffusion; (7) Tensile Tests; and (8) Solid-Solution Strengthening. (Found under Read, Study & Practice.) Tutorial (“Muddiest Point”) Videos. These videos (narrated by a student) help students with concepts that are difficult to understand and with solving troublesome problems. (Found under Read, Study & Practice.) Library of Case Studies. One way to demonstrate principles of design in an engineering curriculum is via case studies: analyses of problem-solving strategies applied to real-world examples of applications/devices/failures encountered by engineers. Six case studies are provided as follows: (1) Materials Selection for a Torsionally Stressed Cylindrical Shaft; (2) Automobile Valve Spring; (3) Failure of an Automobile Rear Axle; (4) Artificial Total Hip Replacement; (5) Intraocular Lens Implants; and (6) Chemical Protective Clothing. (Found under Read, Study & Practice.) Mechanical Engineering (ME) Online Module. This module treats materials science/engineering topics not covered in the printed text that are relevant to mechanical engineering. (Found under Read, Study & Practice.) Flash Cards. A set of flash-cards has been generated for most chapters. These can be used in drills to memorize definitions of terms. (Found under Read, Study & Practice/CONTENTS/Select Chapter Number/CHAPTER RESOURCES/ Flashcards.)  Preface vii Extended Learning Objectives. This is a more extensive list of learning objectives than is provided at the beginning of each chapter. These direct the student to study the subject material to a greater depth. (Found under Read, Study & Practice/ CONTENTS/Select Chapter Number/CHAPTER RESOURCES/Extended Learning Objectives.) Student Lecture Notes. These slides (in PowerPoint and PDF formats) are virtually identical to the lecture slides provided to an instructor for use in the classroom. The student set has been designed to allow for note taking on printouts. (Found under Read, Study & Practice/CONTENTS/Select Chapter Number/CHAPTER RESOURCES/Student Lecture Notes.) Answers to Concept Check questions. Students can visit the web site to find the correct answers to the Concept Check questions posed in the textbook. (Found under Read, Study & Practice/CONTENTS/Select Chapter Number/PRACTICE/ Concept Check Questions/Concept Check Number/Show Solution.) Online Self-Assessment Exercises. A set of questions and problems for each chapter that are similar to those found in the text. An answer to each problem/question entered by the student is assessed as either correct or incorrect, after which both the solution and answer are provided. (Found under Read, Study & Practice/CONTENTS/ Select Chapter Number/PRACTICE/Practice Questions and Problems.) Math Skills Review. This is a tutorial that includes instructions on how to solve a variety of mathematical equations, some of which appear in the homework problems. Examples are also provided. (Found under Read, Study & Practice/ CONTENTS/Chapter 22.) What do instructors receive with WileyPLUS? WileyPLUS provides reliable, customizable resources that reinforce course goals inside and outside of the classroom as well as visibility into individual student progress. Prepared materials and activities help instructors optimize their time. The same resources are provided as are found for students as noted above. The opportunity to pre-prepare activities, including: Questions Readings and resources Presentations Course materials and assessment content: Complete set of Lecture PowerPoint slides (or Lecture Notes). (Found under Prepare & Present/Resources/Select Chapter Number/All Sources/Instructor Resources/PowerPoint/GO/Lecture Notes.) Image Gallery. Digital repository of images from the text that instructors may use to generate their own PowerPoint slides. (Found under Prepare & Present/ Resources/Select Chapter Number/All Sources/Instructor Resources/PowerPoint/ GO/Image Gallery.) Solutions Manual (Textbook). The manuals contain solutions/answers for all problems/questions in the textbook. (Found under Prepare & Present/Resources/ Select Chapter Number/All Sources/Instructor Resources/Document/GO/Chapter Solutions Manual.) Solutions Manual (ME Online Module). (Found under Prepare & Present/ Resources/Mechanical Engineering Module/All Sources/Instructor Resources/ Document/GO/Solutions for ME Module.) viii Preface Solutions Manual (Library of Case Studies). (Found under Prepare & Present/ Resources/Select Any Chapter/All Sources/Instructor Resources/Document/GO/ Solutions to the Library Case Studies/Word or PDF.) Problem Conversion Guide. This guide correlates homework problems/questions between the previous and current textbook editions. (Found under Prepare & Present/Resources/Select Any Chapter/All Sources/Instructor Resources/ Document/GO/Problem Conversion Guide: 9th edition to 10th edition.) Problems/Questions. Selected problems coded algorithmically with hints, links to text, whiteboard/show work feature and instructor controlled problem solving help. [Found under Assignment/Questions/Select Chapter Number/Select Section Number (or All Sections)/Select Level (or All Levels)/All Sources/GO.] Answers to Concept Check Questions. (Found under Assignment/Questions/Select Chapter Number/All Sections/All Levels/All Sources/GO/Question Name.) List of Classroom Demonstrations and Laboratory Experiments. These demos and experiments portray phenomena and/or illustrate principles that are discussed in the book; references are also provided that give more detailed accounts of them. (Found under Prepare & Present/Resources/Select Any Chapter/All Sources/ Instructor Resources/All File Types/GO/Experiments and Classroom Demonstrations.) Suggested Course Syllabi for the Various Engineering Disciplines. Instructors may consult these syllabi for guidance in course/lecture organization and planning. (Found under Prepare & Present/Resources/Select Any Chapter/All Sources/ Instructor Resources/All File Types/GO/Sample Syllabi.) Gradebook. WileyPLUS provides instant access to reports on trends in class performance, student use of course materials and progress towards learning objectives, helping inform decisions and drive classroom discussions. (Found under Gradebook.) STUDENT AND INSTRUCTOR COMPANION SITES (www.wiley.com/college/callister) For introductory materials science and engineering courses that do not use WileyPLUS, print and digital (for purchase) versions of the book are available. In addition, online resources may be accessed on a Student Companion Site (for students) and an Instructor Companion Site (for instructors). Some, but not all of the WileyPLUS resources are found on these two sites. The following resources may be accessed on the STUDENT COMPANION SITE: Student Lecture PowerPoint Slides Answers to Concept Check Questions Extended Learning Objectives Mechanical Engineering (ME) Online Module Math Skills Review Whereas for the INSTRUCTOR COMPANION SITE the following resources are available: Solutions Manuals (in PDF and Word formats) Answers to Concept Check Questions Problem Conversion Guide Complete Set of Lecture PowerPoint Slides Extended Learning Objectives  Preface ix Image Gallery. Mechanical Engineering (ME) Online Module Solutions to Problems in the ME Online Module Suggested Syllabi for the Introductory Materials Course Math Skills Review Feedback We have a sincere interest in meeting the needs of educators and students in the materi- als science and engineering community, and therefore solicit feedback on this edition. Comments, suggestions, and criticisms may be submitted to the authors via email at the fol- lowing address: [email protected]. Acknowledgments Since we undertook the task of writing this and previous editions, instructors and students, too numerous to mention, have shared their input and contributions on how to make this work more effective as a teaching and learning tool. To all those who have helped, we express our sincere thanks. We express our appreciation to those who have made contributions to this edition. We are especially indebted to the following for their feedback and suggestions for this edition: Eric Hellstrom of Florida State University Marc Fry and Hannah Melia of Granta Design Dr. Carl Wood Norman E. Dowling of Virginia Tech Tristan J. Tayag of Texas Christian University Jong-Sook Lee of Chonnam National University, Gwangju, Korea We are also indebted to Linda Ratts, Executive Editor; Agie Sznajdrowicz, Project Manager; Adria Giattino, Associate Development Editor; Adriana Alecci, Editorial Assistant; Jen Devine, Permissions Manager; Ashley Patterson, Production Editor; and MaryAnn Price, Senior Photo Editor. Last, but certainly not least, we deeply and sincerely appreciate the continual encouragement and support of our families and friends. William D. Callister, Jr. David G. Rethwisch September 2017  Contents LIST OF SYMBOLS xix Important Terms and Concepts 46 References 47 1. Introduction 1 3. The Structure of Crystalline Learning Objectives 2 Solids 48 1.1 Historical Perspective 2 Learning Objectives 49 1.2 Materials Science and Engineering 3 3.1 Introduction 49 1.3 Why Study Materials Science and Engineering? 5 CRYSTAL STRUCTURES 49 Case Study—Liberty Ship Failures 6 3.2 Fundamental Concepts 49 1.4 Classification of Materials 7 3.3 Unit Cells 50 Case Study—Carbonated Beverage 3.4 Metallic Crystal Structures 51 Containers 12 3.5 Density Computations 57 1.5 Advanced Materials 14 3.6 Polymorphism and Allotropy 57 1.6 Modern Materials’ Needs 16 Material of Importance—Tin (Its Summary 17 Allotropic Transformation) 58 References 18 3.7 Crystal Systems 59 CRYSTALLOGRAPHIC POINTS, DIRECTIONS, AND PLANES 61 2. Atomic Structure and Interatomic Bonding 19 3.8 Point Coordinates 61 3.9 Crystallographic Directions 64 Learning Objectives 20 3.10 Crystallographic Planes 70 2.1 Introduction 20 3.11 Linear and Planar Densities 76 ATOMIC STRUCTURE 20 3.12 Close-Packed Crystal Structures 77 2.2 Fundamental Concepts 20 CRYSTALLINE AND NONCRYSTALLINE 2.3 Electrons in Atoms 22 MATERIALS 79 2.4 The Periodic Table 28 3.13 Single Crystals 79 ATOMIC BONDING IN SOLIDS 30 3.14 Polycrystalline Materials 79 3.15 Anisotropy 81 2.5 Bonding Forces and Energies 30 3.16 X-Ray Diffraction: Determination of 2.6 Primary Interatomic Bonds 32 Crystal Structures 82 2.7 Secondary Bonding or van der Waals 3.17 Noncrystalline Solids 87 Bonding 39 Summary 88 Materials of Importance—Water (Its Equation Summary 90 Volume Expansion Upon Freezing) 42 List of Symbols 90 2.8 Mixed Bonding 43 Important Terms and Concepts 91 2.9 Molecules 44 References 91 2.10 Bonding Type-Material Classification Correlations 44 4. Imperfections in Solids 92 Summary 45 Equation Summary 46 Learning Objectives 93 List of Symbols 46 4.1 Introduction 93 xi xii Contents POINT DEFECTS 93 PLASTIC DEFORMATION 154 4.2 Vacancies and Self-Interstitials 93 6.6 Tensile Properties 154 4.3 Impurities in Solids 95 6.7 True Stress and Strain 161 4.4 Specification of Composition 98 6.8 Elastic Recovery After Plastic MISCELLANEOUS IMPERFECTIONS 102 Deformation 164 6.9 Compressive, Shear, and Torsional 4.5 Dislocations—Linear Defects 102 Deformations 165 4.6 Interfacial Defects 105 6.10 Hardness 165 Materials of Importance—Catalysts (and Surface Defects) 108 PROPERTY VARIABILITY AND DESIGN/SAFETY 4.7 Bulk or Volume Defects 109 FACTORS 171 4.8 Atomic Vibrations 109 6.11 Variability of Material Properties 171 MICROSCOPIC EXAMINATION 110 6.12 Design/Safety Factors 173 Summary 177 4.9 Basic Concepts of Microscopy 110 Important Terms and Concepts 178 4.10 Microscopic Techniques 111 References 178 4.11 Grain-Size Determination 115 Summary 118 Equation Summary 119 7. Dislocations and Strengthening List of Symbols 120 Mechanisms 180 Important Terms and Concepts 120 Learning Objectives 181 References 120 7.1 Introduction 181 DISLOCATIONS AND PLASTIC DEFORMATION 181 5. Diffusion 121 7.2 Basic Concepts 182 Learning Objectives 122 7.3 Characteristics of Dislocations 184 5.1 Introduction 122 7.4 Slip Systems 185 5.2 Diffusion Mechanisms 123 7.5 Slip in Single Crystals 187 5.3 Fick’s First Law 124 7.6 Plastic Deformation of Polycrystalline 5.4 Fick’s Second Law—Nonsteady-State Materials 190 Diffusion 126 7.7 Deformation by Twinning 192 5.5 Factors That Influence Diffusion 130 MECHANISMS OF STRENGTHENING IN METALS 193 5.6 Diffusion in Semiconducting 7.8 Strengthening by Grain Size Reduction 193 Materials 135 7.9 Solid-Solution Strengthening 195 Materials of Importance—Aluminum 7.10 Strain Hardening 196 for Integrated Circuit Interconnects 138 RECOVERY, RECRYSTALLIZATION, AND GRAIN 5.7 Other Diffusion Paths 139 GROWTH 199 Summary 139 7.11 Recovery 199 Equation Summary 140 7.12 Recrystallization 200 List of Symbols 141 7.13 Grain Growth 204 Important Terms and Concepts 141 Summary 206 References 141 Equation Summary 208 List of Symbols 208 Important Terms and Concepts 208 6. Mechanical Properties of Metals 142 References 208 Learning Objectives 143 6.1 Introduction 143 8. Failure 209 6.2 Concepts of Stress and Strain 144 ELASTIC DEFORMATION 148 Learning Objectives 210 8.1 Introduction 210 6.3 Stress–Strain Behavior 148 6.4 Anelasticity 151 FRACTURE 211 6.5 Elastic Properties of Materials 151 8.2 Fundamentals of Fracture 211  Contents xiii 8.3 Ductile Fracture 211 THE IRON–CARBON SYSTEM 287 8.4 Brittle Fracture 213 9.18 The Iron–Iron Carbide (Fe–Fe3C) Phase 8.5 Principles of Fracture Mechanics 215 Diagram 287 8.6 Fracture Toughness Testing 224 9.19 Development of Microstructure in FATIGUE 229 Iron–Carbon Alloys 290 8.7 Cyclic Stresses 229 9.20 The Influence of Other Alloying 8.8 The S–N Curve 231 Elements 298 8.9 Crack Initiation and Propagation 235 Summary 298 Equation Summary 300 8.10 Factors That Affect Fatigue Life 237 List of Symbols 301 8.11 Environmental Effects 239 Important Terms and Concepts 301 CREEP 240 References 302 8.12 Generalized Creep Behavior 240 8.13 Stress and Temperature Effects 241 10. Phase Transformations: Development 8.14 Data Extrapolation Methods 244 of Microstructure and Alteration of 8.15 Alloys for High-Temperature Use 245 Mechanical Properties 303 Summary 246 Equation Summary 248 Learning Objectives 304 List of Symbols 249 10.1 Introduction 304 Important Terms and Concepts 249 PHASE TRANSFORMATIONS 304 References 249 10.2 Basic Concepts 304 10.3 The Kinetics of Phase Transformations 305 9. Phase Diagrams 251 10.4 Metastable Versus Equilibrium States 316 Learning Objectives 252 MICROSTRUCTURAL AND PROPERTY CHANGES IN 9.1 Introduction 252 IRON–CARBON ALLOYS 317 DEFINITIONS AND BASIC CONCEPTS 252 10.5 Isothermal Transformation Diagrams 317 9.2 Solubility Limit 253 10.6 Continuous-Cooling Transformation 9.3 Phases 254 Diagrams 328 9.4 Microstructure 254 10.7 Mechanical Behavior of Iron–Carbon 9.5 Phase Equilibria 254 Alloys 331 9.6 One-Component (or Unary) Phase 10.8 Tempered Martensite 335 Diagrams 255 10.9 Review of Phase Transformations and Mechanical Properties for Iron–Carbon BINARY PHASE DIAGRAMS 256 Alloys 338 9.7 Binary Isomorphous Systems 257 Materials of Importance—Shape-Memory 9.8 Interpretation of Phase Diagrams 259 Alloys 341 9.9 Development of Microstructure in Summary 344 Isomorphous Alloys 263 Equation Summary 345 9.10 Mechanical Properties of Isomorphous List of Symbols 346 Alloys 266 Important Terms and Concepts 346 9.11 Binary Eutectic Systems 266 References 346 9.12 Development of Microstructure in Eutectic Alloys 272 11. Applications and Processing Materials of Importance—Lead-Free of Metal Alloys 347 Solders 273 Learning Objectives 348 9.13 Equilibrium Diagrams Having Intermediate 11.1 Introduction 348 Phases or Compounds 279 9.14 Eutectoid and Peritectic Reactions 282 TYPES OF METAL ALLOYS 349 9.15 Congruent Phase Transformations 283 11.2 Ferrous Alloys 349 9.16 Ceramic and Ternary Phase 11.3 Nonferrous Alloys 361 Diagrams 284 Materials of Importance—Metal Alloys 9.17 The Gibbs Phase Rule 284 Used for Euro Coins 372 xiv Contents FABRICATION OF METALS 373 13.9 Carbons 453 11.4 Forming Operations 373 13.10 Advanced Ceramics 456 11.5 Casting 375 FABRICATION AND PROCESSING OF 11.6 Miscellaneous Techniques 376 CERAMICS 461 11.7 3D Printing (Additive Manufacturing) 378 13.11 Fabrication and Processing of Glasses and THERMAL PROCESSING OF METALS 382 Glass–Ceramics 462 11.8 Annealing Processes 382 13.12 Fabrication and Processing of Clay 11.9 Heat Treatment of Steels 384 Products 466 11.10 Precipitation Hardening 394 13.13 Powder Pressing 471 Summary 401 13.14 Tape Casting 473 Important Terms and Concepts 403 13.15 3D Printing of Ceramic Materials 474 References 403 Summary 476 Important Terms and Concepts 478 References 478 12. Structures and Properties of Ceramics 405 14. Polymer Structures 479 Learning Objectives 406 12.1 Introduction 406 Learning Objectives 480 CERAMIC STRUCTURES 406 14.1 Introduction 480 14.2 Hydrocarbon Molecules 480 12.2 Crystal Structures 407 14.3 Polymer Molecules 483 12.3 Silicate Ceramics 415 14.4 The Chemistry of Polymer 12.4 Carbon 419 Molecules 483 12.5 Imperfections in Ceramics 420 14.5 Molecular Weight 487 12.6 Diffusion in Ionic Materials 424 14.6 Molecular Shape 490 12.7 Ceramic Phase Diagrams 425 14.7 Molecular Structure 492 MECHANICAL PROPERTIES 428 14.8 Molecular Configurations 493 12.8 Brittle Fracture of Ceramics 429 14.9 Thermoplastic and Thermosetting 12.9 Stress–Strain Behavior 433 Polymers 496 12.10 Mechanisms of Plastic 14.10 Copolymers 497 Deformation 435 14.11 Polymer Crystallinity 498 12.11 Miscellaneous Mechanical 14.12 Polymer Crystals 502 Considerations 437 14.13 Defects in Polymers 504 Summary 439 14.14 Diffusion in Polymeric Materials 505 Equation Summary 440 Summary 507 List of Symbols 441 Equation Summary 509 Important Terms and Concepts 441 List of Symbols 509 References 441 Important Terms and Concepts 510 References 510 13. Applications and Processing of Ceramics 442 15. Characteristics, Applications, and Learning Objectives 443 Processing of Polymers 511 13.1 Introduction 443 Learning Objectives 512 TYPES AND APPLICATIONS OF CERAMICS 444 15.1 Introduction 512 13.2 Glasses 444 MECHANICAL BEHAVIOR OF POLYMERS 512 13.3 Glass–Ceramics 444 15.2 Stress–Strain Behavior 512 13.4 Clay Products 446 15.3 Macroscopic Deformation 515 13.5 Refractories 446 15.4 Viscoelastic Deformation 515 13.6 Abrasives 449 15.5 Fracture of Polymers 519 13.7 Cements 451 15.6 Miscellaneous Mechanical 13.8 Ceramic Biomaterials 452 Characteristics 521  Contents xv MECHANISMS OF DEFORMATION AND FOR 16.5 Influence of Fiber Orientation and STRENGTHENING OF POLYMERS 522 Concentration 573 15.7 Deformation of Semicrystalline 16.6 The Fiber Phase 581 Polymers 522 16.7 The Matrix Phase 583 15.8 Factors That Influence the Mechanical 16.8 Polymer-Matrix Composites 583 Properties of Semicrystalline 16.9 Metal-Matrix Composites 589 Polymers 524 16.10 Ceramic-Matrix Composites 590 Materials of Importance—Shrink-Wrap 16.11 Carbon–Carbon Composites 592 Polymer Films 528 16.12 Hybrid Composites 592 15.9 Deformation of Elastomers 528 16.13 Processing of Fiber-Reinforced Composites 593 CRYSTALLIZATION, MELTING, AND GLASS- TRANSITION PHENOMENA IN POLYMERS 530 STRUCTURAL COMPOSITES 595 15.10 Crystallization 531 16.14 Laminar Composites 595 15.11 Melting 532 16.15 Sandwich Panels 597 15.12 The Glass Transition 532 Case Study—Use of Composites in the 15.13 Melting and Glass Transition Boeing 787 Dreamliner 599 Temperatures 532 16.16 Nanocomposites 600 15.14 Factors That Influence Melting and Glass Summary 602 Equation Summary 605 Transition Temperatures 534 List of Symbols 606 POLYMER TYPES 536 Important Terms and Concepts 606 15.15 Plastics 536 References 606 Materials of Importance—Phenolic 17. Corrosion and Degradation Billiard Balls 539 of Materials 607 15.16 Elastomers 539 15.17 Fibers 541 Learning Objectives 608 15.18 Miscellaneous Applications 542 17.1 Introduction 608 15.19 Polymeric Biomaterials 543 CORROSION OF METALS 609 15.20 Advanced Polymeric Materials 545 17.2 Electrochemical Considerations 609 POLYMER SYNTHESIS AND PROCESSING 549 17.3 Corrosion Rates 615 15.21 Polymerization 549 17.4 Prediction of Corrosion Rates 617 15.22 Polymer Additives 551 17.5 Passivity 624 15.23 Forming Techniques for Plastics 553 17.6 Environmental Effects 625 15.24 Fabrication of Elastomers 555 17.7 Forms of Corrosion 625 15.25 Fabrication of Fibers and Films 555 17.8 Corrosion Environments 633 15.26 3D Printing of Polymers 557 17.9 Corrosion Prevention 633 Summary 560 17.10 Oxidation 636 Equation Summary 562 CORROSION OF CERAMIC MATERIALS 639 List of Symbols 562 Important Terms and Concepts 563 DEGRADATION OF POLYMERS 639 References 563 17.11 Swelling and Dissolution 640 17.12 Bond Rupture 642 16. Composites 564 17.13 Weathering 643 Summary 644 Learning Objectives 565 Equation Summary 646 16.1 Introduction 565 List of Symbols 646 PARTICLE-REINFORCED COMPOSITES 567 Important Terms and Concepts 647 References 647 16.2 Large-Particle Composites 567 16.3 Dispersion-Strengthened Composites 571 18. Electrical Properties 648 FIBER-REINFORCED COMPOSITES 572 Learning Objectives 649 16.4 Influence of Fiber Length 572 18.1 Introduction 649 xvi Contents ELECTRICAL CONDUCTION 649 Materials of Importance—Invar 18.2 Ohm’s Law 649 and Other Low-Expansion Alloys 705 18.3 Electrical Conductivity 650 19.4 Thermal Conductivity 706 18.4 Electronic and Ionic Conduction 651 19.5 Thermal Stresses 709 18.5 Energy Band Structures in Summary 711 Equation Summary 712 Solids 651 List of Symbols 712 18.6 Conduction in Terms of Band and Important Terms and Concepts 713 Atomic Bonding Models 653 References 713 18.7 Electron Mobility 655 18.8 Electrical Resistivity of Metals 656 18.9 Electrical Characteristics of Commercial 20. Magnetic Properties 714 Alloys 659 Learning Objectives 715 SEMICONDUCTIVITY 659 20.1 Introduction 715 18.10 Intrinsic Semiconduction 659 20.2 Basic Concepts 715 18.11 Extrinsic Semiconduction 662 20.3 Diamagnetism and Paramagnetism 719 18.12 The Temperature Dependence of Carrier 20.4 Ferromagnetism 721 Concentration 665 20.5 Antiferromagnetism 18.13 Factors That Affect Carrier Mobility 667 and Ferrimagnetism 722 18.14 The Hall Effect 671 20.6 The Influence of Temperature on Magnetic 18.15 Semiconductor Devices 673 Behavior 726 20.7 Domains and Hysteresis 727 ELECTRICAL CONDUCTION IN IONIC CERAMICS 20.8 Magnetic Anisotropy 730 AND IN POLYMERS 679 20.9 Soft Magnetic Materials 731 18.16 Conduction in Ionic Materials 680 Materials of Importance—An 18.17 Electrical Properties of Polymers 680 Iron–Silicon Alloy Used in DIELECTRIC BEHAVIOR 681 Transformer Cores 732 20.10 Hard Magnetic Materials 733 18.18 Capacitance 681 20.11 Magnetic Storage 736 18.19 Field Vectors and Polarization 683 20.12 Superconductivity 739 18.20 Types of Polarization 686 Summary 742 18.21 Frequency Dependence of the Dielectric Equation Summary 744 Constant 688 List of Symbols 744 18.22 Dielectric Strength 689 Important Terms and Concepts 745 18.23 Dielectric Materials 689 References 745 OTHER ELECTRICAL CHARACTERISTICS OF MATERIALS 689 21. Optical Properties 746 18.24 Ferroelectricity 689 Learning Objectives 747 18.25 Piezoelectricity 690 21.1 Introduction 747 Material of Importance—Piezoelectric Ceramic Ink-Jet Printer Heads 691 BASIC CONCEPTS 747 Summary 692 21.2 Electromagnetic Radiation 747 Equation Summary 695 21.3 Light Interactions with Solids 749 List of Symbols 696 21.4 Atomic and Electronic Interactions 750 Important Terms and Concepts 696 References 697 OPTICAL PROPERTIES OF METALS 751 OPTICAL PROPERTIES OF NONMETALS 752 21.5 Refraction 752 19. Thermal Properties 698 21.6 Reflection 754 Learning Objectives 699 21.7 Absorption 754 19.1 Introduction 699 21.8 Transmission 758 19.2 Heat Capacity 699 21.9 Color 758 19.3 Thermal Expansion 703 21.10 Opacity and Translucency in Insulators 760  Contents xvii APPLICATIONS OF OPTICAL Appendix B Properties of Selected PHENOMENA 761 Engineering Materials A-3 21.11 Luminescence 761 B.1 Density A-3 21.12 Photoconductivity 761 B.2 Modulus of Elasticity A-6 Materials of Importance—Light-Emitting B.3 Poisson’s Ratio A-10 Diodes 762 B.4 Strength and Ductility A-11 21.13 Lasers 764 B.5 Plane Strain Fracture Toughness A-16 21.14 Optical Fibers in Communications 768 B.6 Linear Coefficient of Thermal Summary 770 Expansion A-18 Equation Summary 772 B.7 Thermal Conductivity A-21 List of Symbols 773 B.8 Specific Heat A-24 Important Terms and Concepts 773 B.9 Electrical Resistivity A-27 References 774 B.10 Metal Alloy Compositions A-30 22. Environmental, and Societal Appendix C Costs and Relative Costs for Issues in Materials Science Selected Engineering Materials A-32 and Engineering 775 Appendix D Repeat Unit Structures for Learning Objectives 776 Common Polymers A-37 22.1 Introduction 776 22.2 Environmental and Societal Appendix E Glass Transition and Melting Considerations 776 Temperatures for Common Polymeric 22.3 Recycling Issues in Materials Science Materials A-41 and Engineering 779 Glossary G-1 Materials of Importance—Biodegradable and Biorenewable Polymers/ Index I-1 Plastics 784 Summary 786 References 786 List of Symbols Appendix A The International System of Units (SI) A-1  List of Symbols T he number of the section in which a symbol is introduced or explained is given in parentheses. A = area dhkl = interplanar spacing for planes Å = angstrom unit of Miller indices h, k, and l Ai = atomic weight of (3.16) element i (2.2) E = energy (2.5) APF = atomic packing factor (3.4) E = modulus of elasticity or a = lattice parameter: unit cell Young’s modulus (6.3) x-axial length (3.4) ℰ = electric field intensity (18.3) a = crack length of a surface crack Ef = Fermi energy (18.5) (8.5) Eg = band gap energy (18.6) at% = atom percent (4.4) Er(t) = relaxation modulus (15.4) B = magnetic flux density %EL = ductility, in percent elongation (induction) (20.2) (6.6) Br = magnetic remanence (20.7) e = electric charge per electron BCC = body-centered cubic crystal (18.7) structure (3.4) e– = electron (17.2) b = lattice parameter: unit cell erf = Gaussian error function (5.4) y-axial length (3.7) exp = e, the base for natural b = Burgers vector (4.5) logarithms C = capacitance (18.18) F = force, interatomic or Ci = concentration (composition) of mechanical (2.5, 6.2) component i in wt% (4.4) ℱ = Faraday constant (17.2) Cʹi = concentration (composition) of FCC = face-centered cubic crystal component i in at% (4.4) structure (3.4) C𝜐, Cp = heat capacity at constant G = shear modulus (6.3) volume, pressure (19.2) H = magnetic field strength (20.2) CPR = corrosion penetration rate Hc = magnetic coercivity (20.7) (17.3) HB = Brinell hardness (6.10) CVN = Charpy V-notch (8.6) HCP = hexagonal close-packed crystal %CW = percent cold work (7.10) structure (3.4) c = lattice parameter: unit cell HK = Knoop hardness (6.10) z-axial length (3.7) HRB, HRF = Rockwell hardness: B and F c = velocity of electromagnetic scales (6.10) radiation in a vacuum (21.2) HR15N, HR45W = superficial Rockwell hardness: D = diffusion coefficient (5.3) 15N and 45W scales (6.10) D = dielectric displacement (18.19) HV = Vickers hardness (6.10) DP = degree of polymerization (14.5) h = Planck’s constant (21.2) d = diameter (hkl) = Miller indices for a crystallo- d = average grain diameter (7.8) graphic plane (3.10) xix xx List of Symbols (hkil) = Miller indices for a crystal- r = reaction rate (17.3) lographic plane, hexagonal rA, rC = anion and cation ionic radii crystals (3.10) (12.2) I = electric current (18.2) S = fatigue stress amplitude (8.8) I = intensity of electromagnetic SEM = scanning electron microscopy radiation (21.3) or microscope i = current density (17.3) T = temperature iC = corrosion current density (17.4) Tc = Curie temperature (20.6) J = diffusion flux (5.3) TC = superconducting critical J = electric current density (18.3) temperature (20.12) Kc = fracture toughness (8.5) Tg = glass transition temperature KIc = plane strain fracture tough- (13.10, 15.12) ness for mode I crack surface Tm = melting temperature displacement (8.5) TEM = transmission electron k = Boltzmann’s constant (4.2) microscopy or microscope k = thermal conductivity (19.4) TS = tensile strength (6.6) l = length t = time lc = critical fiber length (16.4) tr = rupture lifetime (8.12) ln = natural logarithm Ur = modulus of resilience (6.6) log = logarithm taken to base 10 [u𝜐w] = indices for a crystallographic M = magnetization (20.2) direction (3.9) — Mn = polymer number-average [uvtw], [UVW] = indices for a crystallographic molecular weight (14.5) direction, hexagonal crystals — M w = polymer weight-average (3.9) molecular weight (14.5) V = electrical potential difference mol% = mole percent (voltage) (17.2, 18.2) N = number of fatigue cycles (8.8) VC = unit cell volume (3.4) NA = Avogadro’s number (3.5) VC = corrosion potential (17.4) Nf = fatigue life (8.8) VH = Hall voltage (18.14) n = principal quantum number (2.3) Vi = volume fraction of phase i (9.8) n = number of atoms per unit cell 𝜐 = velocity (3.5) vol% = volume percent n = strain-hardening exponent (6.7) Wi = mass fraction of phase i (9.8) n = number of electrons in an wt% = weight percent (4.4) electrochemical reaction (17.2) x = length n = number of conducting elec- x = space coordinate trons per cubic meter (18.7) Y = dimensionless parameter or n = index of refraction (21.5) function in fracture toughness nʹ = for ceramics, the number of expression (8.5) formula units per unit cell y = space coordinate (12.2) z = space coordinate ni = intrinsic carrier (electron and α = lattice parameter: unit cell y–z hole) concentration (18.10) interaxial angle (3.7) P = dielectric polarization (18.19) α, 𝛽, 𝛾 = phase designations P–B ratio = Pilling–Bedworth ratio (17.10) αl = linear coefficient of thermal p = number of holes per cubic expansion (19.3) meter (18.10) 𝛽 = lattice parameter: unit cell x–z Q = activation energy interaxial angle (3.7) Q = magnitude of charge stored 𝛾 = lattice parameter: unit cell x–y (18.18) interaxial angle (3.7) R = atomic radius (3.4) 𝛾 = shear strain (6.2) R = gas constant ∆ = precedes the symbol of a pa- %RA = ductility, in percent reduction rameter to denote finite change in area (6.6) ε = engineering strain (6.2) r = interatomic distance (2.5) ε = dielectric permittivity (18.18)  List of Symbols xxi εr = dielectric constant or relative σʹm = stress in matrix at composite permittivity (18.18) failure (16.5) ε·S = steady-state creep rate (8.12) σT = true stress (6.7) εT = true strain (6.7) σw = safe or working stress (6.12) η = viscosity (12.10) σy = yield strength (6.6) η = overvoltage (17.4) τ = shear stress (6.2) 2θ = Bragg diffraction angle (3.16) τc = fiber–matrix bond strength/ θD = Debye temperature (19.2) matrix shear yield strength λ = wavelength of electromagnetic (16.4) radiation (3.16) τcrss = critical resolved shear stress μ = magnetic permeability (20.2) (7.5) μB = Bohr magneton (20.2) χm = magnetic susceptibility μr = relative magnetic permeability (20.2) (20.2) μe = electron mobility (18.7) μh = hole mobility (18.10) Subscripts ν = Poisson’s ratio (6.5) c = composite ν = frequency of electromagnetic cd = discontinuous fibrous radiation (21.2) composite ρ = density (3.5) cl = longitudinal direction (aligned ρ = electrical resistivity (18.2) fibrous composite) ρt = radius of curvature at the tip of ct = transverse direction (aligned a crack (8.5) fibrous composite) σ = engineering stress, tensile or f = final compressive (6.2) f = at fracture σ = electrical conductivity (18.3) f = fiber σ* = longitudinal strength (compos- i = instantaneous ite) (16.5) m = matrix σc = critical stress for crack propa- m, max = maximum gation (8.5) min = minimum σfs = flexural strength (12.9) 0 = original σm = maximum stress (8.5) 0 = at equilibrium σm = mean stress (8.7) 0 = in a vacuum  Chapter 1 Introduction © iStockphoto/Mark Oleksiy © blickwinkel/Alamy A familiar item fabricated from three different material types is the © iStockphoto/Jill Chen beverage container. Beverages are marketed in aluminum (metal) cans (top), glass (ceramic) bottles (center), and plastic (polymer) bottles (bottom). © iStockphoto/Mark Oleksiy © blickwinkel/Alamy 1 Learning Objectives After studying this chapter, you should be able to do the following: 1. List six different property classifications of 4. (a) List the three primary classifications materials that determine their applicability. of solid materials, and then cite the 2. Cite the four components that are involved in distinctive chemical feature of each. the design, production, and utilization of materials, (b) Note the four types of advanced materials and briefly describe the interrelationships and, for each, its distinctive feature(s). between these components. 5. (a) Briefly define smart material/system. 3. Cite three criteria that are important in the (b) Briefly explain the concept of nanotechnology materials selection process. as it applies to materials. 1.1 HISTORICAL PERSPECTIVE Please take a few moments and reflect on what your life would be like without all of the materials that exist in our modern world. Believe it or not, without these materials we wouldn’t have automobiles, cell phones, the internet, airplanes, nice homes and their furnishings, stylish clothes, nutritious (also “junk”) food, refrigerators, televisions, computers... (and the list goes on). Virtually every segment of our everyday lives is influenced to one degree or another by materials. Without them our existence would be much like that of our Stone Age ancestors. Historically, the development and advancement of societies have been intimately tied to the members’ ability to produce and manipulate materials to fill their needs. In fact, early civilizations have been designated by the level of their materials development (Stone Age, Bronze Age, Iron Age).1 The earliest humans had access to only a very limited number of materials, those that occur naturally: stone, wood, clay, skins, and so on. With time, they discovered techniques for producing materials that had properties superior to those of the natural ones; these new materials included pottery and various metals. Furthermore, it was discovered that the properties of a material could be altered by heat treatments and by the addition of other substances. At this point, materials utilization was totally a selection process that involved deciding from a given, rather limited set of materials, the one best suited for an application by virtue of its characteristics. It was not until relatively recent times that scientists came to understand the relationships between the structural elements of materials and their proper- ties. This knowledge, acquired over approximately the past 100 years, has empowered them to fashion, to a large degree, the characteristics of materials. Thus, tens of thousands of dif- ferent materials have evolved with rather specialized characteristics that meet the needs of our modern and complex society, including metals, plastics, glasses, and fibers. The development of many technologies that make our existence so comfortable has been intimately associated with the accessibility of suitable materials. An advance- ment in the understanding of a material type is often the forerunner to the stepwise progression of a technology. For example, automobiles would not have been possible without the availability of inexpensive steel or some other comparable substitute. In the contemporary era, sophisticated electronic devices rely on components that are made from what are called semiconducting materials. 1 The approximate dates for the beginnings of the Stone, Bronze, and Iron ages are 2.5 million bc, 3500 bc, and 1000 bc, respectively. 2  1.2 Materials Science and Engineering 3 1.2 MATERIALS SCIENCE AND ENGINEERING Sometimes it is useful to subdivide the discipline of materials science and engineering into materials science and materials engineering subdisciplines. Strictly speaking, materials science involves investigating the relationships that exist between the structures and properties of materials (i.e., why materials have their properties). In contrast, materials engineering involves, on the basis of these structure–property correlations, designing or engineering the structure of a material to produce a predetermined set of properties. From a functional perspective, the role of a materials scientist is to develop or synthesize new materials, whereas a materials engineer is called upon to create new products or systems using existing materials and/or to develop techniques for processing materials. Most graduates in materials programs are trained to be both materials scientists and materials engineers. Structure is, at this point, a nebulous term that deserves some explanation. In brief, the structure of a material usually relates to the arrangement of its internal components. Structural elements may be classified on the basis of size and in this regard there are several levels: Subatomic structure—involves electrons within the individual atoms, their energies and interactions with the nuclei. Atomic structure—relates to the organization of atoms to yield molecules or crystals. Nanostructure—deals with aggregates of atoms that form particles (nanoparticles) that have nanoscale dimensions (less that about 100 nm). Microstructure—those structural elements that are subject to direct observation using some type of microscope (structural features having dimensions between 100 nm and several millimeters). Macrostructure—structural elements that may be viewed with the naked eye (with scale range between several millimeters and on the order of a meter). Atomic structure, nanostructure, and microstructure of materials are investigated using microscopic techniques discussed in Section 4.10. The notion of property deserves elaboration. While in service use, all materials are exposed to external stimuli that evoke some types of responses. For example, a speci- men subjected to forces experiences deformation, or a polished metal surface reflects light. A property is a material trait in terms of the kind and magnitude of response to a specific imposed stimulus. Generally, definitions of properties are made independent of material shape and size. Virtually all important properties of solid materials may be grouped into six differ- ent categories: mechanical, electrical, thermal, magnetic, optical, and deteriorative. For each, there is a characteristic type of stimulus capable of provoking different responses. These are noted as follows: Mechanical properties—relate deformation to an applied load or force; examples include elastic modulus (stiffness), strength, and resistance to fracture. Electrical properties—the stimulus is an applied electric field; typical properties in- clude electrical conductivity and dielectric constant. Thermal properties—are related to changes in temperature or temperature gradients across a material; examples of thermal behavior include thermal expansion and heat capacity. Magnetic properties—the responses of a material to the application of a magnetic field; common magnetic properties include magnetic susceptibility and magnetization. Optical properties—the stimulus is electromagnetic or light radiation; index of re- fraction and reflectivity are representative optical properties. 4 Chapter 1 / Introduction Figure 1.1 Three thin disk specimens of aluminum oxide that have been placed over a printed page in order to demonstrate their William D. Callister Jr./ Specimen preparation, differences in light-transmittance characteristics. The disk on the left is transparent (i.e., virtually all light that is reflected from the page passes through it), whereas the one in the center is translucent (meaning that some of this reflected light is transmitted through the disk). The disk on the right is opaque—that is, none of the light passes through it. These differences in optical properties are a consequence of differences in structure of these materials, which have resulted P.A. Lessing from the way the materials were processed. Deteriorative characteristics—relate to the chemical reactivity of materials; for example, corrosion resistance of metals. The chapters that follow discuss properties that fall within each of these six classifications. In addition to structure and properties, two other important components are in- volved in the science and engineering of materials—namely, processing and performance. With regard to the relationships of these four components, the structure of a material depends on how it is processed. Furthermore, a material’s performance is a function of its properties. We present an example of these processing-structure-properties-performance principles in Figure 1.1, a photograph showing three thin disk specimens placed over some printed matter. It is obvious that the optical properties (i.e., the light transmit- tance) of each of the three materials are different; the one on the left is transparent (i.e., virtually all of the reflected light from the printed page passes through it), whereas the disks in the center and on the right are, respectively, translucent and opaque. All of these specimens are of the same material, aluminum oxide, but the leftmost one is what we call a single crystal—that is, has a high degree of perfection—which gives rise to its transparency. The center one is composed of numerous and very small single crystals that are all connected; the boundaries between these small crystals scatter a portion of the light reflected from the printed page, which makes this material optically translu- cent. Finally, the specimen on the right is composed not only of many small, intercon- nected crystals, but also of a large number of very small pores or void spaces. These pores scatter the reflected light to a greater degree than the crystal boundaries and render this material opaque. Thus, the structures of these three specimens are different in terms of crystal boundaries and pores, which affect the optical transmittance proper- ties. Furthermore, each material was produced using a different processing technique. If optical transmittance is an important parameter relative to the ultimate in-service application, the performance of each material will be different. This interrelationship among processing, structure, properties, and performance of materials may be depicted in linear fashion as in the schematic illustration shown in Figure 1.2. The model represented by this diagram has been called by some the central paradigm of materials science and engineering or sometimes just the materials paradigm. (The term “paradigm” means a model or set of ideas.) This paradigm, formulated in the 1990s is, in essence, the core of the discipline of materials science and engineering. It describes the protocol for selecting and designing materials for specific and well-defined  1.3 Why Study Materials Science and Engineering? 5 Processing Structure Properties Performance Figure 1.2 The four components of the discipline of materials science and engineering and their interrelationship. applications, and has had a profound influence on the field of materials.2 Previous to this time the materials science/engineering approach was to design components and systems using the existing palette of materials. The significance of this new paradigm is reflected in the following quotation: “... whenever a material is being created, developed, or produced, the properties or phenomena the material exhibits are of central concern. Experience shows that the properties and phenomena associated with a material are intimately related to its composition and structure at all levels, including which atoms are present and how the atoms are arranged in the material, and that this structure is the result of synthesis and processing.”3 Throughout this text, we draw attention to the relationships among these four com- ponents in terms of the design, production, and utilization of materials. 1.3 WHY STUDY MATERIALS SCIENCE AND ENGINEERING? Why do engineers and scientists study materials? Simply, because things engineers design are made of materials. Many an applied scientist or engineer (e.g., mechanical, civil, chemi- cal, electrical), is at one time or another exposed to a design problem involving materials— for example, a transmission gear, the superstructure for a building, an oil refinery com- ponent, or an integrated circuit chip. Of course, materials scientists and engineers are specialists who are totally involved in the investigation and design of materials. Many times, an engineer has the option of selecting a best material from the thousands available. The final decision is normally based on several criteria. First, the in-service conditions must be characterized, for these dictate the properties required of the material. Only on rare occasions does a material possess the optimum or ideal com- bination of properties. Thus, it may be necessary to trade one characteristic for another. The classic example involves strength and ductility; normally, a material having a high strength has only a limited ductility. In such cases, a reasonable compromise between two or more properties may be necessary. A second selection consideration is any deterioration of material properties that may occur during service operation. For example, significant reductions in mechanical strength may result from exposure to elevated temperatures or corrosive environments. Finally, probably the overriding consideration is that of economics: What will the fin- ished product cost? A material may be found that has the optimum set of properties but is prohibitively expensive. Here again, some compromise is inevitable. The cost of a finished piece also includes any expense incurred during fabrication to produce the desired shape. The more familiar an engineer or scientist is with the various characteristics and structure–property relationships, as well as the processing techniques of materials, the more proficient and confident he or she will be in making judicious materials choices based on these criteria. 2 This paradigm has recently been updated to include the component of material sustainability in the “Modified Paradigm of Materials Science and Engineering,” as represented by the following diagram: Processing → Structure → Properties → Performance → Reuse/Recyclability 3 “Materials Science and Engineering for the 1990s,” p. 27, National Academies Press, Washington, DC, 1998. 6 Chapter 1 / Introduction C A S E S T U D Y 1.1 Liberty Ship Failures T he following case study illustrates one role that materials scientists and engineers are called upon to assume in the area of materials performance: cracks formed, grew to critical lengths, and then rapidly propagated completely around the ships’ girths. Figure 1.3 shows one of the ships that fractured the analyze mechanical failures, determine their causes, day after it was launched. and then propose appropriate measures to guard Subsequent investigations concluded one or more against future incidents. of the following factors contributed to each failure:6 The failure of many of the World War II Liberty ships4 is a well-known and dramatic example of the When some normally ductile metal alloys are brittle fracture of steel that was thought to be ductile.5 cooled to relatively low temperatures, they be- Some of the early ships experienced structural dam- come susceptible to brittle fracture—that is, they age when cracks developed in their decks and hulls. experience a ductile-to-brittle transition upon Three of them catastrophically split in half when cooling through a critical range of temperatures. Figure 1.3 The Liberty ship S.S. Schenectady, which, in 1943, failed before leaving the shipyard. (Reprinted with permission of Earl R. Parker, Brittle Behavior of Engineering Structures, National Academy of Sciences, National Research Council, John Wiley & Sons, New York, 1957.) 4 During World War II, 2,710 Liberty cargo ships were mass-produced by the United States to supply food and materials to the combatants in Europe. 5 Ductile metals fail after relatively large degrees of permanent deformation; however, very little if any permanent deformation accompanies the fracture of brittle materials. Brittle fractures can occur very suddenly as cracks spread rapidly; crack propagation is normally much slower in ductile materials, and the eventual fracture takes longer. For these reasons, the ductile mode of fracture is usually preferred. Ductile and brittle fractures are discussed in Sections 8.3 and 8.4. 6 Sections 8.2 through 8.6 discuss various aspects of failure.  1.4 Classification of Materials 7 These Liberty ships were constructed of steel that Remedial measures taken to correct these prob- experienced a ductile-to-brittle transition. Some lems included the following: of them were deployed to the frigid North Atlantic, Lowering the ductile-to-brittle temperature of where the once ductile metal experienced brittle the steel to an acceptable level by improving steel fracture when temperatures dropped to below the quality (e.g., reducing sulfur and phosphorus im- transition temperature.7 purity contents). The corner of each hatch (i.e., door) was square; Rounding off hatch corners by welding a curved these corners acted as points of stress concentra- reinforcement strip on each corner.8 tion where cracks can form. Installing crack-arresting devices such as riveted German U-boats were sinking cargo ships faster straps and strong weld seams to stop propagating than they could be replaced using existing con- cracks. struction techniques. Consequently, it became necessary to revolutionize construction methods Improving welding practices and establishing weld- to build cargo ships faster and in greater numbers. ing codes. This was accomplished using prefabricated steel In spite of these failures, the Liberty ship pro- sheets that were assembled by welding rather gram was considered a success for several reasons, than by the traditional time-consuming riveting. the primary reason being that ships that survived Unfortunately, cracks in welded structures may failure were able to supply Allied Forces in the propagate unimpeded for large distances, which theater of operations and in all likelihood shortened can lead to catastrophic failure. However, when the war. In addition, structural steels were developed structures are riveted, a crack ceases to propagate with vastly improved resistances to catastrophic brit- once it reaches the edge of a steel sheet. tle fractures. Detailed analyses of these failures ad- Weld defects and discontinuities (i.e., sites where vanced the understanding of crack formation and cracks can form) were introduced by inexperi- growth, which ultimately evolved into the discipline enced operators. of fracture mechanics. 7 This ductile-to-brittle transition phenomenon, as well as techniques that are used to measure and raise the critical temperature range, are discussed in Section 8.6. 8 The reader may note that corners of windows and doors for all of today’s marine and aircraft structures are rounded. 1.4 CLASSIFICATION OF MATERIALS Solid materials have been conveniently grouped into three basic categories: metals, ceramics, and polymers, a scheme based primarily on chemical makeup and atomic structure. Most materials fall into one distinct grouping or another. In addition, there are the composites that are engineered combinations of two or more different materials. A brief explanation of these material classifications and representative characteristics is offered next. Another category is advanced materials—those used in high-technology applications, such as semiconductors, biomaterials, smart materials, and nanoengi- neered materials; these are discussed in Section 1.5. Metals Tutorial Video: What Are the Metals are composed of one or more metallic elements (e.g., iron, aluminum, copper, Different Classes titanium, gold, nickel), and often also nonmetallic elements (e.g., carbon, nitrogen, of Materials? oxygen) in relatively small amounts.9 Atoms in metals and their alloys are arranged in a 9 The term metal alloy refers to a metallic substance that is composed of two or more elements. 8 Chapter 1 / Introduction Figure 1.4 40 Metals Bar chart of room- temperature density 20 Platinum values for various Silver Density (g/cm3) (logarithmic scale) metals, ceramics, Ceramics 10 8 Copper polymers, and Iron/Steel 6 ZrO2 composite materials. Al2O3 Titanium 4 Polymers Composites SiC,Si3N4 Aluminum Glass GFRC 2 PTFE Concrete Magnesium CFRC PVC PS 1.0 PE 0.8 Rubber 0.6 Woods 0.4 0.2 0.1 very orderly manner (as discussed in Chapter 3) and are relatively dense in comparison to the ceramics and polymers (Figure 1.4). With regard to mechanical characteristics, these materials are relatively stiff (Figure 1.5) and strong (Figure 1.6), yet are ductile (i.e., capable of large amounts of deformation without fracture), and are resistant to fracture (Figure 1.7), which accounts for their widespread use in structural applications. Tutorial Video: Metallic materials have large numbers of nonlocalized electrons—that is, these electrons Metals are not bound to particular atoms. Many properties of metals are directly attributable to these electrons. For example, metals are extremely good conductors of electricity (Figure 1.8) and heat, and are not transparent to visible light; a polished metal surface has a lustrous appearance. In addition, some of the metals (i.e., Fe, Co, and Ni) have desirable magnetic properties. Figure 1.5 Bar chart of room- Metals Ceramics 1000 Composites temperature stiffness Stiffness [elastic (or Young’s) modulus (in units of Tungsten SiC (i.e., elastic modulus) Iron/Steel AI2O3 CFRC values for various 100 Titanium Si3N4 ZrO2 gigapascals)] (logarithmic scale) metals, ceramics, Aluminum Magnesium Glass GFRC polymers, and Concrete composite materials. Polymers Woods 10 PVC PS, Nylon 1.0 PTFE PE 0.1 Rubbers 0.01 0.001  1.4 Classification of Materials 9 Figure 1.6 Bar chart of room- Metals Composites temperature strength Ceramics (i.e., tensile strength) Strength (tensile strength, in units of Steel megapascals) (logarithmic scale) values for various 1000 CFRC alloys Si3N4 metals, ceramics, Cu,Ti GFRC alloys SiC polymers, and Al2O3 Aluminum composite materials. alloys Gold Polymers 100 Glass Nylon Woods PS PVC PTFE PE 10 Figure 1.9 shows several common and familiar objects that are made of metallic materials. Furthermore, the types and applications of metals and their alloys are discussed in Chapter 11. Ceramics Ceramics are compounds between metallic and nonmetallic elements; they are most fre- quently oxides, nitrides, and carbides. For example, common ceramic materials include aluminum oxide (or alumina, Al2O3), silicon dioxide (or silica, SiO2), silicon carbide (SiC), silicon nitride (Si3N4), and, in addition, what some refer to as the traditional ceramics—those composed of clay minerals (e.g., porcelain), as well as cement and glass. With regard to me- Tutorial Video: chanical behavior, ceramic materials are relatively stiff and strong—stiffnesses and strengths Ceramics are comparable to those of the metals (Figures 1.5 and 1.6). In addition, they are typically very hard. Historically, ceramics have exhibited extreme brittleness (lack of ductility) and are highly susceptible to fracture (Figure 1.7). However, newer ceramics are being engineered to have improved resistan