High-Temperature Oxidation Behavior of AlxCoCrFeNiM (M = Cu, Ti, V) High-Entropy Alloys

High-entropy alloys (HEAs) feature a unique combination of mechanical and physical properties, such as high strength and ductility, high hardness and wear resistance, high thermal stability, suggesting that HEAs are suitable for operation under severe conditions (gas turbines, jet and turbojet engines, etc.). In this context, it is reasonable to assess the resistance of HEAs to high-temperature oxidation. Here, we present theoretical and experimental data on the behavior of three HEAs (Al x CoCrFeNiM with M = Cu, Ti, V) oxidized in air at 900°C for 10 h and discuss the possibility of thermodynamic simulation for predicting the composition of their oxidation products. Our study of the microstructure of the test HEAs before and after oxidation, composition of their oxidation products, and oxidation kinetics shows that Al 0.25 CoCrFeNiCu has the highest stability to high-temperature oxidation due to the formation of a protective Al 2 O 3 -rich film on its surface. The oxidation stability of the Ti- and V-doped alloys is rather low and likely because their surface during oxidation is covered with loose layers of transition metal oxides rather with a continuous alumina film.