Textbook in PDF format Preface High-entropy alloys (HEAs) have recently emerged as a versatile class of structural materials, sparking substantial interest in diverse applications. Their high confgurational entropy and phase stability, coupled with their excellent mechanical properties, make them a promising option. By defnition, HEAs consist of fve or more principal metallic elements in near equiatomic ratios and are characterized as having one or more solid solution phases as well as a high entropy of mixing. However, recent defnitions have broadened to include compositionally complex alloys (those that lack high confgurational entropies and have secondary phases), HEAs with only four primary ele ments, and multi-principal element alloys (comprising only two or three of the so-called principal alloying elements). HEA coatings have attracted considerable interest due to their remarkable mechanical and tribo logical properties, as well as their resistance to high-temperature oxidation. These qualities make them suitable candidates as coating materials for extreme operating environments. The selection of the appropriate coating is contingent upon considerations such as the nature of the substrate material, coating thickness, and the intended applications. Besides protective coating applications, HEA coatings have diverse applications in several fields, including energy storage and conversion, electrocatalysis, biomedical, and nuclear sectors. In this book, we aim to provide a comprehensive account of the fundamentals and applications of HEA coatings. This book’s content is suitable for understanding the current state of technology and shaping the future directions for research and development in this field. PART I Fundamentals Chapter 1 High-Entropy Alloys: Fundamental and Frontiers Chapter 2 Mechanistic Aspects of High-Entropy Alloys PART II HEA Coatings Chapter 3 Types and Fabrication Approaches of High-Entropy Alloy Coatings: An Overview Chapter 4 Microstructure and Mechanical Properties of High-Entropy Alloy Coatings: Role of Constituent Elements and Fabrication Approaches Chapter 5 Theoretical and Computational Modeling Studies on High-Entropy Alloy Coatings Chapter 6 Design of Wear- and Corrosion-Resistant Multi-Principal Element Alloy Coatings: Framework and Perspectives on Cr–Co–Ni-Based Coatings Chapter 7 Machine Learning Applied to High-Entropy Alloy Coatings Process Parameters and Composition Optimization: A Case Study PART III Coating Type Chapter 8 Metallic High-Entropy Alloy Coatings Chapter 9 High-Entropy Ceramic Coatings Chapter 10 Composite High-Entropy Alloy Coatings PART IV Fabrication Methods Chapter 11 Laser-Based Methods of High-Entropy Alloy Coating Fabrication Chapter 12 Thermal and Cold Spray High-Entropy Alloy Coatings Chapter 13 Electrochemical Methods of High-Entropy Alloy Coating Fabrication PART V Applications Chapter 15 Anti-Wear and Anti-Friction High-Entropy Alloy Coatings Chapter 16 Anti-Corrosion High-Entropy Alloy Coatings Chapter 17 HEA Coatings for Tribo-Corrosion Applications Chapter 18 Thermal Barrier High-Entropy Alloy Coatings Chapter 19 High-Entropy Alloy Coatings in Energy Storage and Conversion Chapter 20 High-Entropy Ferroelectric Ceramics/Thin Films for Capacitor Energy Storage Applications Chapter 21 HEA Coatings for Electrocatalytic Applications