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High-Entropy Alloys

Book Description

This book provides a complete review of the current state of the art in the field of high entropy alloys (HEA). The conventional approach to alloy design is to select one principal element and add elements to it in minor quantities in order to improve the properties. In 2004, Professor J.W. Yeh and his group first reported a new approach to alloy design, which involved mixing elements in equiatomic or near-equiatomic proportions, to form multi-component alloys with no single principal element. These alloys are expected to have high configurational entropy and hence were termed as "high entropy alloys." HEAs have a broad range of structures and properties, and may find applications in structural, electrical, magnetic, high-temperature, wear-resistant, corrosion-resistant, and oxidation-resistant components. Due to their unique properties, high entropy alloys have attracted considerable attention from both academics and technologists. This book presents the fundamental knowledge present in the field, the spectrum of various alloy systems and their characteristics studied to date, current key focus areas, and the future scope of the field in terms of research and technological applications.

Table of Contents

  1. Cover image
  2. Title page
  3. Copyright
  4. Foreword
  5. Preface
  6. Acknowledgements
  7. Chapter 1. A Brief History of Alloys and the Birth of High-Entropy Alloys
    1. 1.1 Introduction
    2. 1.2 The Coming of Alloys
    3. 1.3 Special Alloys
    4. 1.4 The Coming of Multicomponent Heas
    5. 1.5 The Scope of This Book
  8. Chapter 2. High-Entropy Alloys: Basic Concepts
    1. 2.1 Introduction
    2. 2.2 Classification of Phase Diagrams and Alloy Systems
    3. 2.3 Definition of HEAs
    4. 2.4 Composition Notation
    5. 2.5 Four Core Effects of HEAs
  9. Chapter 3. Phase Selection in High-Entropy Alloys
    1. 3.1 Predicting Solid Solubility from Hume-Rothery Rules
    2. 3.2 Mutual Solubility and Phase Formation Tendency in HEAs
    3. 3.3 Parametric Approaches to Predict Crystalline Solid Solution and Metallic Glass
    4. 3.4 Pettifor Map Approach to Predict the Formation of Intermetallic Compound, Quasicrystal, and Glass
    5. 3.5 Phase Separation Approach to Find Single-Phase HEAs
  10. Chapter 4. Alloy Design in the Twenty-First Century: ICME and Materials Genome Strategies
    1. 4.1 Introduction
    2. 4.2 Integrated Computational Materials Engineering
  11. Chapter 5. Synthesis and Processing
    1. 5.1 Introduction
    2. 5.2 Melting and Casting Route
    3. 5.3 Solid-State Processing Route
    4. 5.4 HEA and HEA-Based Coatings
    5. 5.5 Combinatorial Materials Synthesis
  12. Chapter 6. High-Entropy Alloy Solid Solutions
    1. 6.1 Introduction
    2. 6.2 Solid Solution Formation in Equiatomic HEAs
    3. 6.3 Solid Solution Formation in Nonequiatomic HEAs
    4. 6.4 Microstructure of HEAs
    5. 6.5 Role of Sluggish Diffusion in Phase Evolution of HEAs
    6. 6.6 Thermal Stability of HEAs
  13. Chapter 7. Intermetallics, Interstitial Compounds and Metallic Glasses in High-Entropy Alloys
    1. 7.1 Introduction
    2. 7.2 Intermetallic Compounds
    3. 7.3 Interstitial Compounds (Hagg Phases)
    4. 7.4 Metallic Glasses
  14. Chapter 8. Structural Properties
    1. 8.1 Introduction
    2. 8.2 Mechanical Properties
    3. 8.3 Wear Properties
    4. 8.4 Electrochemical Properties
    5. 8.5 Oxidation Behavior
  15. Chapter 9. Functional Properties
    1. 9.1 Introduction
    2. 9.2 Diffusion Barrier Properties
    3. 9.3 Electrical Properties
    4. 9.4 Thermal Properties
    5. 9.5 Magnetic Properties
    6. 9.6 Hydrogen Storage Properties
    7. 9.7 Irradiation Resistance
    8. 9.8 Catalytic Properties
  16. Chapter 10. Applications and Future Directions
    1. 10.1 Introduction
    2. 10.2 Goals of Property Improvement
    3. 10.3 Advanced Applications Demanding New Materials
    4. 10.4 Examples of Applications
    5. 10.5 Patents on HEAs and Related Materials
    6. 10.6 Future Directions
  17. References
  18. Appendix 1
  19. Appendix 2