Multi-Principal Element Alloy Coatings: A Review of Deposition Techniques, Applications, and Future Prospects

Multi-principal element alloy (MPEA) coatings, including medium entropy alloys (MEAs) and high entropy alloys (HEAs), have emerged as transformative materials with the potential to address critical challenges in industrial applications. These coatings offer exceptional properties such as high-temperature oxidation resistance, wear resistance, corrosion protection, and thermal stability, making them ideal for demanding environments. This review primarily focuses on MEA coatings, providing a comprehensive analysis of their deposition techniques, applications, and future prospects. The review highlights the key advantages of MEA coatings over traditional single-element or binary alloy coatings, emphasizing their superior toughness, strength, and deformability. Various deposition methods, including laser-based techniques, thermal spraying, physical and chemical vapor deposition, and electrodeposition, are discussed in detail, with an evaluation of their benefits and limitations. Where specific studies on MEAs are unavailable, insights from HEA coatings are incorporated to provide complementary perspectives, leveraging the shared characteristics of these multi-principal element systems. Applications of MPEA coatings in aerospace, automotive, biomedical, energy, and oil and gas industries are explored, showcasing their ability to enhance performance, durability, and efficiency. Future research directions are identified, including the development of novel compositions, advancements in deposition technologies, and a deeper understanding of structure–property relationships. The review also emphasizes the need for scalable, cost-effective manufacturing processes to accelerate the adoption of MPEA coatings in various sectors. By presenting a focused yet inclusive perspective on MPEA coatings, this review aims to serve as a valuable resource for researchers, engineers, and industry stakeholders working toward the advancement and widespread utilization of these innovative materials.

Graphical Abstract