Yong Zhang is a Professor and Doctoral Supervisor at Beijing University of Science and Technology in the State Key Laboratory for Advanced Metals and Materials. Yonggang Yao is a Professor and Doctoral Supervisor at Huazhong University of Science and Technology. Haojie Liu is Ph.D in School of Materials Science and Engineering, Huazhong University of Science and Technology, China.

• Contributors viiForeword ixPreface xi1 High-Entropy Alloys and Compounds: Fundamentals 11.1 Introduction (Historical Background and Development) 11.2 Definition of HEAs and Compounds 31.3 Characteristics, Structures, Phase Transformations, and Microstructures 61.3.1 Characteristics of HEAs and Compounds 71.3.2 Crystal Structures of HEAs and Compounds 121.3.3 Phase Transformations in HEAs and Compounds 141.3.4 Microstructures of HEAs and Compounds 181.4 Diverse Applications of Functional HEAs and Compounds 25References 342 Extreme Conditions and Novel Structure Design 432.1 Introduction to Extreme Conditions and Harsh Requirements 432.2 HEMs for Extreme Temperatures 442.2.1 The Application of HEM at High Temperatures 442.2.2 The Application of HEMs at Low Temperatures 482.3 HEMs Sustain Under Strong Irradiations 522.3.1 Anti-Irradiation Mechanism of HEAs 532.3.2 Evolution of Microstructure and Defects 572.3.3 Mechanical Changes Caused by Irradiation 612.3.4 High-Entropy Ceramics 622.4 Fiber and Single-Crystal HEMs 642.4.1 HEA Fibers 642.4.2 Single-Crystal HEA 69References 713 Corrosion and Antioxidation 753.1 Introduction to Corrosion and Antioxidation Scenario 753.2 Anticorrosion Design in High-Entropy Materials 773.2.1 Effect of Alloying Elements 783.2.2 Effect of Processing 813.3 High-Temperature Oxidation Resistance 823.3.1 Oxidation Mechanism 843.3.2 Influencing Factors 88References 934 Additive Manufacturing and Phase Control 974.1 Introduction to Additive Manufacturing Technologies 974.2 3D Printing of High-Entropy Materials 1014.2.1 Introduction of HEAs for 3D Printing 1014.2.2 Classification of HEAs for 3D Printing 1024.3 Shape Design and Phase Control in High-Entropy Materials by 3D Printing 1034.3.1 Phase Structure of HEAs 1034.3.2 The Influence of Printing Parameters on the Phase Structure 1044.3.3 Effect of Alloying Elements on Phase Structure 1054.3.4 Research Progress on Additive Production of HEAs 1064.4 Applications of 3D Printed High-Entropy Materials 1144.4.1 Energy Industry 1144.4.2 Aerospace Industry 1154.4.3 Nuclear Application 1164.4.4 Medical Applications 1174.4.5 Coating Application 118References 1185 Functional Properties: Thermal, Electric, Magnetic, and Optics 1295.1 Introduction to Functional Properties and Applications 1295.2 Thermal and Electronic Properties in HEMs 1305.2.1 Thermal Conduction in HEMs 1305.2.2 Superconducting in High-Entropy Materials 1325.2.3 High-Entropy Materials for Thermoelectric Applications 1345.2.4 Conclusion 1385.3 Magnetic and Optical Properties in HEMs 1395.3.1 Magnetic Properties in High-Entropy Materials 1395.3.2 Optical Properties in High-Entropy Materials 1425.3.3 High-Entropy Materials for Optoelectronic Applications 1455.3.4 Conclusion 1495.4 Materials Design for Functional Applications 1505.4.1 Microstructure Regulation 1515.4.2 Machine Learning-Assisted Design 156References 1626 Nanoscale High-Entropy Materials 1656.1 Introduction to Evolution from Bulk to Nanoscale HEMs 1656.2 Synthesis and Advanced Characterization 1666.2.1 Top-Down Method 1676.2.2 Bottom-Up Method 1706.2.3 Perspectives for HEM Synthesis 1726.3 Diverse Applications of Nanoscale HEMs 1746.3.1 HEMs as Electrocatalysts 1746.3.2 Nano-HEAs as an Irradiation-Resistant Structural Material 1776.3.3 Nano-HEAs for Solid Hydrogen Storage Properties 1796.3.4 Nano-HEAs for Biomedical Fields 1806.4 Emerging Nano-HEAs 182References 1827 High-Entropy Materials for Thermal-Catalytic Applications 1937.1 Introduction to Thermal Catalysis and Important Concepts 1937.1.1 Definition and Background 1937.1.2 The Role of Catalysts in Thermal Reactions 1947.1.3 Thermodynamics and Kinetics in Catalysis 1957.1.4 Catalyst Activation and Deactivation 1967.1.5 Selectivity and Activity in Thermal Catalysis 1987.2 Catalysts Evolution to HEMs 2007.2.1 Transition from Single-Component to Multicomponent Catalysts 2007.2.2 Strategies to Stabilize High-Entropy Catalysts 2017.3 Typical Reactions and Their High-Entropy Catalysts 2037.3.1 Hydrotreatment Reactions 2037.3.2 Oxidation and Ammoxidation 2067.3.3 Dehydrogenation and Decomposition Reaction 2107.3.4 Catalyst Performance Comparison 2147.4 Understanding of High-Entropy Catalysts 2157.4.1 Structural Characteristics Influencing Catalysis 2157.4.2 Electronic Effects and Ligand Effects 2177.4.3 Entropy’s Role in Stabilizing Catalytic Active Phases 2197.4.4 Mechanistic Insights Through Theoretical Calculations and Spectroscopy 2217.4.5 Designing HEA Catalysts for Specific Reactions 221References 2238 Clean Energy and Electrocatalysis 2278.1 Introduction to Electrocatalysis and Its Importance 2278.2 Application of High-Entropy Alloys in Key Reactions of Electrocatalysis 2278.3 Advanced Ex/In Situ Characterization Techniques 2348.3.1 Electron Spectroscopy 2428.4 High-Throughput and Data-Driven Techniques in High-Entropy Catalyst Development 244References 2489 High-Entropy Materials for Energy Storage Applications 2539.1 Introduction to High-Entropy Materials for Battery Applications 2539.2 High-Entropy Anode Materials 2549.3 High-Entropy Cathode Materials 2589.4 High-Entropy Solid-State Electrolytes 2639.4.1 High-Entropy Oxide Solid-State Electrolytes 2649.4.2 High-Entropy Sulfide Solid-State Electrolytes 2689.4.3 High-Entropy Halide Solid-State Electrolytes 2719.5 High-Entropy Liquid Electrolytes 2739.6 Perspectives on High-Entropy Battery Materials 274References 27710 Future Trends and Concluding Regards 28310.1 Key Challenges Presented in Functional High-Entropy Alloy and Compounds 28310.1.1 Synthesis Challenges 28310.1.2 Characterization Challenges 28510.1.3 Theoretical Challenges 28710.1.4 Application Challenges 29010.2 Future Development of Functional HEA and Compounds 29210.2.1 High-Throughput Exploration of ML 29310.2.2 Statistical Methods 29310.2.3 Artificial Neuron Networks 29510.3 Concluding Regards: Materials Evolution from Simple to a Complex Yet Fruitful Future 297References 297Index 301