Phase Transformations in Metals and Alloys

Transcription

1 Phase Transformations in Metals and Alloys THIRD EDITION DAVID A. PORTER, KENNETH E. EASTERLING, and MOHAMED Y. SHERIF ( г йс) CRC Press ^ ^ ) Taylor & Francis Group Boca Raton London New York CRC Press is an imprint of the Taylor & Francis Group, an informa business

2 Contents Preface to the Third Edition Preface to the Second Edition Preface to the First Edition Authors xiii xv xvii xix Chapter 1 Thermodynamics and Phase Diagrams Equilibrium Single-Component Systems Gibbs Free Energy as a Function of Temperature Pressure Effects Driving Force for Solidification Binary Solutions Gibbs Free Energy of Binary Solutions Ideal Solutions Chemical Potential Regular Solutions Activity Real Solutions Ordered Phases Intermediate Phases Equilibrium in Heterogeneous Systems Binary Phase Diagrams Simple Phase Diagram Systems with a Miscibility Gap Ordered Alloys Simple Eutectic Systems Phase Diagrams Containing Intermediate Phases Gibbs Phase Rule Effect of Temperature on Solid Solubility Equilibrium Vacancy Concentration Influence of Interfaces on Equilibrium Ternary Equilibrium Additional Thermodynamic Relationships for Binary Solutions Computation of Phase Diagrams Pure Stoichiometric Substances Solution Phases Substitutional Solutions 56 vii

3 viii Contents 1.10 Kinetics of Phase Transformations 57 Exercises 58 References 60 Further Reading 61 Chapter 2 Diffusion Atomic Mechanisms of Diffusion Interstitial Diffusion Interstitial Diffusion as a Random Jump Process Effect of Temperature Thermal Activation Steady-State Diffusion Nonsteady-State Diffusion Solutions to the Diffusion Equation Homogenization Carburization of Steel Substitutional Diffusion Self-Diffusion Vacancy Diffusion Diffusion in Substitutional Alloys Diffusion in Dilute Substitutional Alloys Atomic Mobility Tracer Diffusion in Binary Alloys Diffusion in Ternary Alloys High-Diffusivity Paths Diffusion along Grain Boundaries and Free Surfaces Diffusion along Dislocations Diffusion in Multiphase Binary Systems 104 Exercises 106 References 109 Further Reading 110 Chapter 3 Crystal Interfaces and Microstructure Ill 3.1 Interracial Free Energy Solid/Vapor Interfaces Boundaries in Single-Phase Solids Low-Angle and High-Angle Boundaries Special High-Angle Grain Boundaries Equilibrium in Polycrystalline Materials Thermally Activated Migration of Grain Boundaries Kinetics of Grain Growth Interphase Interfaces in Solids Interface Coherence Fully Coherent Interfaces Semicoherent Interfaces Incoherent Interfaces Complex Semicoherent Interfaces 145

4 Contents! ix Second-Phase Shape: Interfacial Energy Effects Fully Coherent Precipitates Partially Coherent Precipitates Incoherent Precipitates Precipitates on Grain Boundaries Second-Phase Shape: Misfit Strain Effects Fully Coherent Precipitates Incoherent Inclusions Platelike Precipitates Coherency Loss Glissile Interfaces Solid/Liquid Interfaces Interface Migration Diffusion-Controlled and Interface-Controlled Growth 170 Exercises 176 References 178 Further Reading 179 Chapter 4 Solidification Nucleation in Pure Metals Homogeneous Nucleation Homogeneous Nucleation Rate Heterogeneous Nucleation Nucleation of Melting Growth of a Pure Solid Continuous Growth Lateral Growth Heat Flow and Interface Stability Alloy Solidification Solidification of Single-Phase Alloys Eutectic Solidification Off-Eutectic Alloys Peritectic Solidification Solidification of Ingots and Castings Ingot Structure Segregation in Ingots and Castings Continuous Casting Solidification of Fusion Welds Solidification during Quenching from the Melt Metallic Glasses Thermodynamics and Kinetics Case Studies of Some Practical Castings and Welds Casting of Carbon and Low-Alloy Steels Casting of High-Speed Steels 241 Exercises 247

5 X Contents References 249 Further Reading 249 Chapter 5 Diffusional Transformations in Solids Homogeneous Nucleation in Solids Heterogeneous Nucleation Rate of Heterogeneous Nucleation Precipitate Growth Growth behind Planar Incoherent Interfaces Diffusion-Controlled Lengthening of Plates or Needles Thickening of Platelike Precipitates Overall Transformation Kinetics: TTT Diagrams Precipitation in Age-Hardening Alloys Precipitation in Aluminum-Copper Alloys Precipitation in Aluminum-Silver Alloys Quenched-In Vacancies Age Hardening Spinodal Decomposition Particle Coarsening Precipitation of Ferrite from Austenite Case Study: Ferrite Nucleation and Growth Cellular Precipitation Eutectoid Transformations Pearlite Reaction in Fe-C Alloys Bainite Transformation Effect of Alloying Elements on Hardenability Continuous Cooling Diagrams Fibrous and Interphase Precipitation in Alloy Steels Rule of Scheil Massive Transformations Ordering Transformations Case Studies Titanium Forging Alloys Weldability of Low-Carbon and Microalloyed Rolled Steels Very Low-Carbon Bainitic Steel with High Strength and Toughness Very Fine Bainite 357 Exercises 360 References 362 Further Reading 364 Chapter 6 Diffusionless Transformations Characteristics of Diffusionless Transformations Solid Solution of Carbon in Iron Martensite Crystallography 373

6 Contents xi Bain Model of the fee * bet Transformation Comparison of Crystallographic Theory with Experimental Results Theories of Martensite Nucleation Formation of Coherent Nuclei of Martensite Role of Dislocations in Martensite Nucleation Dislocation Strain Energy Assisted Transformation Martensite Growth Growth of Lath Martensite Plate Martensite Stabilization Effect of External Stresses Role of Grain Size Premartensite Phenomena Tempering of Ferrous Martensites Case Studies Carbon and Low-Alloy Quenched and Tempered Steels Controlled Transformation Steels TRIP-Assisted Steels "Shape-Memory" Metal: Nitinol 415 Exercises 417 References 418 Further Reading 420 Solutions to Exercises 421 Index 491