Tribological properties of nano/ultrafine-grained FeCoCrNiMnAlx high-entropy alloys over a wide range of temperatures

Abstract Previous studies have shown that high-entropy alloys (HEAs) have good wear resistance, especially at elevated temperatures. However, for nano/ultrafine-grained bulk HEAs, there is a lack of understanding of the friction and wear properties. In this work, nano/ultrafine-grained FeCoCrNiMnAlx HEAs were produced by powder metallurgy, and the effects of Al addition and temperature on the friction and wear properties of the alloys were studied. The addition of Al led to grain refinement, body-centered cubic (BCC) phase precipitation and an increased hardness, which significantly improved the wear resistance of the alloys at various temperatures. At elevated temperatures, such as 800 °C, the alloys (especially the Al-containing alloys) exhibited outstanding wear resistance, which was mainly attributed to the formation of the continuous and dense oxide film on the worn surface due to the nano-/ultrafine-grained structure. Additionally, the Al-containing alloys also showed good antifriction properties at 800 °C.