1st Edition
High-Entropy Alloy Coatings Fundamentals and Applications
PART I: Fundamentals
1. High-Entropy Alloys: Fundamental and Frontiers
Muhammad Abubaker Khan, Mohamed A. Afifi, Jamieson Brechtl
1.1. Introduction
1.2. Thermodynamic and Composition design of HEAs
1.2.1. The concept behind HEAs: Four Core Effects
1.3. Microstructure evaluation
1.4. Mechanical Properties
1.5. Corrosion Resistance
1.6. High entropy alloy coatings
1.7. Applications of HEAs
1.7.1. High temperature applications
1.7.2. Aerospace and Automotive Industries
1.7.3. Nuclear Energy
1.7.4. Energy Storage and Renewable Energy
1.7.5. Coatings and Surface Engineering
1.7.6. Other Emerging Applications
1.8. Challenges
1.9. Conclusions and outlook
References
2. Mechanistic aspects of High-Entropy Alloys
Yuan Yu, Yiming Luo, Zhuhui Qiao
2.1. Introduction
2.2. Structural Defects
2.2.1 Vacancies
2.2.2 Dislocations
2.2.3 Stacking Faults
2.2.4 Interfaces
2.3. Diffusion Mechanisms
2.4. Plastic Deformation Mechanisms
2.4.1. Slip
2.4.2 Twinning-induced Plasticity
2.4.3 Transformation-Induced Plasticity
2.5. Strengthening Mechanisms
2.5.1 Solid-solution Strengthening
2.5.2 Grain Boundary Strengthening
2.5.3 Dislocation strengthening
2.5.4 Precipitation Strengthening
2.6. Heterogeneous Structure
2.7. Conclusions and outlook
Acknowledgment
References
PART II: HEA coatings
3. Types and fabrication approaches of high-entropy alloy coatings – An overview
Himanshu Kumar, Mohd Rafiq Parray, Amritbir Singh, S. Shiva
3.1. Introduction
3.2. Types of HEA coatings
3.2.1. HEA-based ceramic coatings
3.2.2. HEA-based composite coatings
3.2.3. Metal-based HEA coatings
3.3. Fabrication methods of HEA coatings
3.3.1. Chemical and electrochemical methods
3.3.2. Laser-based approaches
3.3.3. Powder Metallurgy
3.3.4 Vapour based HEA coatings
3.4. Applications of HEA coatings
3.4.1 Aerospace
3.4.2 Electronic devices
3.4.3 Hydrogen storage
3.4.4 Biomedical
3.4.5 Nuclear
3.5. Conclusions and outlook
References
4. Microstructures and mechanical properties of High-Entropy Alloy coatings – Role of constituent elements and fabrication approaches
Ameey Anupam, Pawan Kumar, Harpreet Singh
4.1. Introduction
4.2 Role of Constituent Elements
4.2.1. How to choose elements
4.2.2. Parameters for solid solution formation
4.2.3 Predictive tools
4.2.4 Case Study: AlCoCrFeNi family of HEAs
4.3 Fabrication Approaches
4.3.1 Thermal spray
4.3.2. Melt pool-based methods
4.3.3. Vapor based methods (thin films)
4.4 Effect of coating microstructure and fabrication technique on HEA coating properties: Thermal Spray vs. Melt Pool based methods
4.4.1 As coated microstructure
4.4.2 Major strengthening mechanisms utilized in HEA coatings
4.4.3 Post processing
4.5. Mechanical Property Testing
4.5.1 Microhardness
4.5.2 Nanoindentation
4.5.3 Adhesion/cohesion testing
4.5.4 Other methods – in-situ micropillar compression testing
4.5.5 Importance of statistics in analysis of mechanical property
4.6. Conclusions and Outlook
References
5. Theoretical and computer modelling studies on high-entropy alloy coatings
Harsh Jain, Tejasva Vashistha, Prasad Baddi, Raghavan Ranganathan
5.1. Introduction
5.1.1 High-Entropy Alloys
5.1.2 High-Entropy Alloy Coatings
5.2 Molecular Dynamics simulations of HEA coatings
5.2.1 Modeling the Deposition Process using Molecular Dynamics
5.2.2 Mechanical Properties of HEA Coatings Using MD Simulations
5.3 Density Functional Theory (DFT) simulations of HEA coatings
5.3.1 DFT Modelling Parameters
5.3.2 Basic Terminologies and Concepts
5.3.3 Applications of DFT simulations in HEA coatings
5.4. Conclusions and outlook
References
6. Design of wear- and corrosion-resistant multi-principal element alloy coatings: Framework and Perspectives on Cr-Co-Ni based alloys
Guilherme Yuuki Koga, Luana Cristina Miguel Rodrigues, Claudemiro Bolfarini, Walter José Botta, Francisco Gil Coury
6.1. Introduction
6.2. Cr-Co-Ni alloys
6.3. Cr-Co-Ni coatings
6.3.1. Thin Cr-Co-Ni coatings
6.3.2. Thermally sprayed Cr-Co-Ni coatings
6.3.3. Thick Cr-Co-Ni coatings
6.5. Conclusions and outlook
References
7. Machine learning applied to high-entropy alloy coatings process parameters and composition optimization – A case study
Raffaella Sesana, Mohsen Dehghanpour Abyaneh, Marzieh Golabchi, Luca Corsaro, Nazanin Sheibanian, Sedat Ozbilen
7.1 Introduction
7.2. Experimental characterization and data preprocessing
7.2.1 Data Preprocesssing
7.2.2 Statistical analysis
7.2.3 Machine Learning Implementation
7.2.4. Surface roughness
7.2.5. Volume variation
7.2.6. Sensitivity Analysis
7.2.7. Taylor Evaluation
7.3 Conclusions and outlook
Acknowledgment
References
PART III: Coating type
8. Metallic high-entropy alloy coatings
Avinash V. Ingle
8.1 Introduction
8.1.1 Definition and concept of HEAs
8.1.2 Importance and relevance of HEAs in modern materials science
8.1.3 Overview of metallic coatings
8.2 Synthesis and fabrication techniques of HEA coatings
8.2.1 PVD techniques
8.2.2 CVD techniques
8.2.3 Electrochemical deposition
8.2.4 Thermal spray techniques
8.2.5 Other emerging techniques
8.3 Microstructure and phase evolution in HEA coatings
8.3.1 Phase formation in HEAs
8.3.2 Solid solution strengthening mechanisms
8.3.3 Microstructural features
8.4 Mechanical properties of HEA coatings
8.4.1 Hardness
8.4.2 Strength
8.4.3 Wear resistance
8.4.4 Fracture toughness and ductility
8.5 Corrosion resistance of HEA coatings
8.5.1 Electrochemical behavior and corrosion mechanisms in HEA coatings
8.5.2 Comparative analysis with conventional alloys
8.6 Oxidation resistance
8.6.1 High-temperature oxidation behavior
8.7 Applications of HEA coatings
8.7.1 High-temperature oxidation-resistant coatings for supercritical boilers
8.7.2 Wear-resistant coatings
8.7.3 Energy sector: nuclear reactors
8.7.4 Biomedical applications
8.7.5 Electronics and optics
8.8 Challenges and future directions
8.8.1 Current challenges in HEA coating development
8.9 Potential for industrial adoption
8.10 Conclusions and outlook
References
9. High-entropy ceramic coatings
Jingchuan Li, Liangge Xu, Jiaqi Zhu, Sam Zhang
9.1 Introduction
9.2 Fundamentals and classification of High-entropy ceramic coatings
9.3 Production methods
9.3.1 Magnetron sputtering
9.3.2 Vacuum cathodic arc deposition
9.3.3 Pulsed laser deposition
9.3.4 Ultrasonic spray pyrolysis
9.3.5 Atmospheric plasma spraying
9.3.6 Ion implantation
9.4 Types and crystal structures
9.4.1 High-entropy oxide ceramic coatings
9.4.2 High-entropy nitride ceramic coatings
9.4.3 High-entropy carbide ceramic coatings
9.4.4 High-entropy boride ceramic coatings
9.5 Properties and applications
9.5.1 Mechanical properties
9.5.2 Oxidation resistance
9.5.3 Corrosion resistance
9.5.4 Thermal properties
9.5.5 Diffusion resistance for barriers
9.5.6 Electrical properties
9.5.7 Magnetic properties
9.5.8 Optical properties
9.6 Conclusions and outlook
References
10. Composite high-entropy alloy coatings
Chika Oliver Ujah, Sandip Kunar
10.1 Introduction
10.2. Fundamental of High Entropy Alloys
10.2.1. Characteristics of High Entropy Alloys
10.3. Composite High Entropy Alloys (CHEAs)
10.3.1. Characteristics of Composite High Entropy Alloys
10.4. Composite High Entropy Alloy Coatings
10.4.1. Coating Techniques
10.4.2. Applications
10.5. Challenges and Limitations
10.6. Future Directions and Opportunities
10.6.1. Optimizing Composition and Microstructure
10.6.2. Modeling and Simulation
10.6.3. Advancing Fabrication Processes
10.6.4. Enhancing Properties
10.7 Conclusions and outlook
References
Part IV: Fabrication methods
11. Laser-based Methods of High Entropy Alloy Coating Fabrication
JiaSheng Wang, Yong Zhang
11.1. Introduction
11.2 Preparation Processes
11.3 Types of HEA Coatings
11.4 Influence of Preparation Process Parameters
11.5 Microstructural Characteristics
11.6 Performance Advantages
11.6.1 Mechanical Properties
11.6.2 Friction Properties
11.6.3 Corrosion Resistance
11.6.4 Magnetic properties
11.7 Applications
11.8. Conclusions and outlook
12. Thermal and Cold Spray High-Entropy Alloy Coatings
Mohamed Abdrabou Hussein
12.1. Introduction
12.2. Thermal Spray HEA Coatings
12.2.1. Plasma Spraying
12.2.2. High-Velocity Oxygen-Fuel Spraying
12.3. Cold spray HEA coatings
12.4. Conclusions and outlook
Acknowledgment
References
13. Electrochemical Methods of High-Entropy Alloy Coating Fabrication
A. Madhan Kumar
13.1. Introduction
13.2. Electrochemical Methods for HEA Coating Fabrication
13.2.1 HEA coatings processed by Electrochemical routes
13.3. Challenges
13.3.1 Improving Coating Quality and Uniformity
13.3.2 Developing Sustainable Fabrication Techniques
13.4. Conclusions and outlook
References
14. Post-processing approaches for high-entropy alloy-based coatings
Pankaj Rawat, Vivek K Singh, Sanjeev Kumar, Sunil K Pathak, and Shailesh Kumar Singh
14.1. Introduction
14.2. Heat treatment of HEA coatings
14.3. Laser remelting of the HEA coatings
14.4. Friction stir processing (FSP) of the HEA coatings
14.5. Others post-processing techniques
16.6. Conclusions and outlook
References
PART V: Applications
15. Anti-wear and anti-friction high entropy alloy coatings
Nasirudeen O. Ogunlakin, Ankah Nesto, Viswanathan S. Saji
15.1 Introduction
15.2 Fundamentals of Tribological Behavior
15.2.1 Wear Mechanisms
15.2.2 Friction Mechanisms
15.2.3 Role of Surface Oxide Films and Third-Body Particles
15.3 Synthesis and Deposition Techniques for Tribological HEA Coatings
15.3.1 Physical Vapor Deposition (PVD) Methods
15.3.2 Thermal Spray Methods
15.3.3 Laser Cladding Method
15.3.4 Electrochemical and Emerging Methods of Depositing HEA Coatings
15.4 Microstructure–Tribology Relationships in HEA Coatings
15.4.1 Elemental Composition and Phase Stability
15.4.2 Grain Size, Lattice Distortion, and Strengthening Mechanisms
15.4.3 Oxide Scale Formation and Self-Lubrication
15.5 Tribological Performance under Various Operating Conditions
15.5.1 Room-Temperature Applications
15.5.2 Elevated-Temperature Environments
15.5.3 Abrasive and Erosive Environments
15.5.4 Corrosive or Humid Environments
15.6 Challenges and Future Directions
15.6.1 Compositional Complexity and Design Strategies
15.6.2 Large-Scale Manufacturing and Cost
15.6.3 Coating Integrity and Residual Stresses
15.6.4 Sustainability and Life-Cycle Analysis
15.7. Conclusions and outlook
References
16. Anti-corrosion high-entropy alloy coatings
Vinay B. U, Shashi Bhushan Arya
16.1. Introduction
16.2. Limitations of Conventional Corrosion-Resistant Coatings and advantages of HEA coatings.
16.3. Fabrication Techniques for HEA Coatings
16.4. Corrosion types in HEA coatings
16.5. Corrosion Mechanisms in HEA Coatings
16.5.1 Electrochemical Corrosion and Passive Film Formation
16.5.2 Microstructural Stability and Corrosion Performance
16.5.3 Sluggish Diffusion and Delayed Corrosion Kinetics
16.5.4 Lattice Distortion and Its Impact on Corrosive Ion Diffusion
16.5.5 Synergistic Multi-Element Effects Enhancing Corrosion Resistance
16.6. Role of Alloying Elements in HEA Coatings for Anti-Corrosion
16.7. Conclusions and outlook
References
17. High-entropy alloy coatings for tribocorrosion applications
Vinay. B. U, Shashi Bhushan Arya
17.1. Introduction
17.2. Advantages of HEA Coatings in Tribo-corrosion Protection
17.3. Tribo-corrosion Mechanisms of HEA Coatings
17.4. Fabrication Techniques for HEA Tribo-corrosion-Resistant Coatings
17.4.1 Thermal Spray Deposition
17.4.2 Physical and Chemical Vapor Deposition
17.4.3 Electrochemical and electroless deposition techniques
17.4.4 Additive Manufacturing and Laser-Based Coating Techniques
17.5. Experimental Procedure for Evaluating Tribo-Corrosion Performance of HEA Coatings
17.5.1 Wear and Corrosion Tests in Simulated Marine Environments
17.5.2 Factors Affecting Tribo-Corrosion Performance of HEA Coatings
17.6 Challenges and Future Directions in HEA Tribo-Corrosion Coatings
17.6.1 Challenges
17.6.2 Strategies for enhancing tribo-corrosion performance
17.6.3 Emerging Trends and Future Research Directions
17.7. Conclusions and Outlook
References
18. Thermal Barrier High Entropy Alloy coatings
Ankah Nestor, Nasirudeen Ogunlakin, Viswanathan S. Saji
18.1 Introduction
18.2 Fundamentals of HEAs
18.2.1 Types of HEAs
18.2.2 Properties of HEAs Relevant to TBC Applications
18.2.3 Benefits of HEAs over Traditional Bond Coat Materials
18.3 Design Considerations for HEA-Based TBCs
18.3.1 Element Selection
18.3.2 Compatibility with Substrates and Topcoats
18.3.3 Oxidation and Corrosion Resistance
18.3.4 Microstructural Considerations
18.3.5 Synthesis and Processing Techniques
18.4 Experimental Studies on HEA Coatings in TBCs
18.4.1 Comparative Analysis to traditional TBCs
18.4.2 Challenges and Solutions
18.5 Computational Modeling and Predictive Tools for HEA TBCs
18.5.1 Computational Thermodynamics and Phase Stability
18.5.2 Modeling Thermal and Mechanical Properties
18.5.3 Machine Learning and Data-Driven Design
18.5.4 Development of Predictive Models
18.6 Potential Applications and Industrial Relevance of HEA-Based TBCs
18.6.1 Aerospace and Space Exploration
18.6.2 Power Generation and Gas Turbines
18.6.3 Automotive Applications
18.6.4 High-Temperature Industrial Applications
18.7 Challenges and Future Research Directions
18.7.1 Challenges in Developing and Implementing HEA-Based TBCs
18.7.2 Future Research Directions
18.8 Conclusions and Outlook
References
19. High-entropy alloy coatings in energy storage and conversion
Karthika Pichaimuthu
19.1 Introduction
19.2. Theoretical studies on HEMs
19.3. High-entropy Materials for Rechargeable Batteries
19.4. High-entropy Materials for Supercapacitors
19.5. High-entropy Materials for Hydrogen Energy Conversion and Storage
19.5.1. Fuel cells
19.5.2. Hydrogen Storage
19.5.3. Hydrogen Evolution Reaction
19.6. High-entropy Materials for Oxygen Reaction
19.6.1. Oxygen Evolution Reaction
19.6.2. Oxygen Reduction Reaction
19.7. High-entropy Materials for Carbon-dioxide Reduction Reaction
19.8. Other applications
19.9. HEMs Computational Techniques
19.10 Conclusions and outlook
References
20. High–Entropy Ferroelectric Ceramics/Thin Films for Capacitor Energy Storage Applications
Shubham kumar, Kuldeep Singh, Moolchand Sharma, Jagmohan Datt Sharma, Rahul Vaish, Vishal Singh Chauhan, Gurpreet Singh
20.1. Introduction
20.2. Ferroelectric ceramics
20.3. High–entropy ferroelectric ceramics/thin films
20.4. Synthesis of High–entropy ferroelectric ceramics/thin films
20.5. HEFC for capacitor energy storage applications
20.6. HEFC thin films for capacitor energy storage application
20.7. Conclusions and outlook
References
21. HEA coatings in electrocatalytic applications
Yifan Zhou, Changrui Feng, Ziyuan Yang, Juan Zhang, Xiumin Li, Abuliti Abudula, Guoqing Guan
21.1. Introduction
21.2 Classification of HEA coatings
21.2.1 Metallic Type
21.2.2 Ceramic Type
21.2.3 Composite Type
21.3 Synthesis and post-processing of HEA coatings
21.3.1 Synthesis methods
21.3.2 Post-processing approaches
21.4 HEA coatings for electrochemical water/seawater splitting
21.4.1 Foundation of electrochemical water/seawater splitting
21.4.2 HEA coatings for water splitting
21.4.3 HEA coatings for seawater splitting
21.5 HEA coatings for other electrocatalysis
21.5.1 HEA coatings for glycerol oxidation reaction
21.5.2 HEA coatings for methanol oxidation reaction
21.6 Conclusions and outlook
Acknowledgement
References
Biography
Viswanathan S. Saji is a Research Scientist-II at the Interdisciplinary Research Center for Advanced Materials, King Fahd University of Petroleum and Minerals (KFUPM), Saudi Arabia (2022 – present). Jamieson Brechtl is currently an Associate R&D staff member at Oak Ridge National Laboratory (2023 – present).
