Revealing the excellent high-temperature oxidation resistance of a non-equimolar Al1Co25Cr18Fe23Ni23Ta10 compositional complex eutectic alloy

Abstract Refractory high-entropy alloys (RHEAs) usually have a high strength at elevate temperatures. However, their oxidation resistance is inferior for practical applications. Here we proposed a eutectic design of compositionally complex eutectic alloy (CCEA) by adding 10 at. % Ta to the Al2Co28Cr20Fe25Ni25, the resulting alloy shows a good combination of mechanical properties and oxidation resistance, e.g. a yield strength of 764 MPa and an oxidation resistance rate of 0.0031 mg cm−2h−1 at 800 °C, which outperforms those of RHEAs. The excellent oxidation resistance is attributable to the formation of protective Cr2O3 and CrTaO4 layer at the surface, which prevents the matrix from further contact with O2.