Abstract Since 2004, extensive research reports the phase stability, mechanical, functional, oxidation, corrosion and wear properties of high entropy alloys (HEAs). This work presents a comprehensive review of the wear behaviour of HEAs, with a particular emphasis on CoCrFeNi-based and AlCoCrFeNi-based systems, as well as other HEAs and HEA-based coatings. The influence of various processing techniques, including vacuum arc melting (VAM), air plasma spraying (APS), spark plasma sintering (SPS), and laser cladding, on microstructural evolution, hardness, and wear rate is systematically compared and discussed. The role of alloying elements in governing the microstructure, hardness, and wear resistance of CoCrFeNi-based and AlCoCrFeNi-based systems is critically analyzed. High-temperature wear behaviour of HEAs is also reviewed, along with alloy design strategies and their application potential. This review shows that although processing-induced variations in hardness influence wear rates, the dominant wear mechanisms remain largely unchanged across different processing routes. AlCoCrFeNi-based systems exhibit enhanced hardness and reduced wear rates primarily due to Al addition, while other targeted alloying additions (e.g., Ti, Nb, Mo, C, WC, B, Si, graphene, and solid lubricants) significantly contribute to improved wear resistance.
Yadav et al. (2026) studied this question.