Recent advances in tribology of high entropy alloys: A critical review

Wear and friction are two unavoidable failures in mechanical systems with moving components. Hence, the invention of new materials to curtail material losses and frictional energy remains a formidable obstacle in modern times. High entropy alloys (HEAs) introduce a revolutionary alloy design concept focused on several primary elements and vast compositional space. They offer considerable promise for the development of materials with exceptional wear resistance and reduced friction owing to their exceptional thermal stability, high hardness, good corrosion resistance, and superior mechanical strength. Therefore, researchers have shown a growing interest in HEAs over the last decade to obtain outstanding tribological properties that are unachievable with traditional alloys. This review focuses on various aspects of HEAs tribology such as alloying, heat treatment, surface alterations, coatings, and composites under dry and lubricated conditions. A critical assessment of the microstructure developments, manufacturing processes, and parametric variables that govern the tribo-behavior of HEAs also falls under the span of this review. Finally, this review not only highlights the major findings of the preceding research but also proposes future recommendations on the manufacturing and required advancement of HEAs for diverse tribological applications.