Mechanisms of high temperature tribology and oxidation behaviour of cost-effective high-entropy alloys

High-entropy alloys (HEAs) have garnered considerable interest since their inception in 2004, owing to their remarkable properties, including exceptional high strength, low-temperature fracture toughness, good corrosion properties, and high-temperature resistance. HEAs represent an emerging class of materials, distinguished from other metal systems by their five-or-more-component composition, wherein the constituents are present in equiatomic or near-equiatomic proportions, thereby maximizing configurational entropy. Notably, the multi-phase structure and significant Cr or Al content in many HEAs contribute to their favorable tribological performances and high-temperature properties. Consequently, certain HEAs hold substantial promise for diverse industrial applications, particularly as anti-wear materials under high-temperature conditions. Howerver, one of the primary challenges impeding the widespread industrial application of HEAs is their cost. Many existing HEAs consist of a significant proportion of expensive metals, particularly commonly used elements such as cobalt (Co), leading to escalated raw material expenses. Furthermore, the current research regarding HEAs has primarily centered on composition design and microstructure investigation, with limited exploration of wear, friction, and tribolayer composition evolution during high-thermal sliding or rolling processes. This lack of knowledge calls for further investigation to elucidate the tribological behaviors and related phenomena of HEAs under high-temperature conditions.