Oxidation behaviors and mechanical properties of L1(2)-strengthened high-entropy alloys at 700?

Abstract

Oxidation behavior and mechanical properties of two L12-strengthened high-entropy superalloys (HESAs), i.e., (Ni2Co2FeCr)(92)Ti4Al4 and (Ni2Co2FeCr)92Nb4Al4, were systematically investigated at 700 & DEG;C. Our results reveal that the oxidation resistance was significantly improved by the replacement of Ti with Nb with slightly optimized mechanical performance. The substitution of Ti by Nb promotes the formation of continuous Cr2O3, AlNbO4, and Al2O3 layers, and causes a remarkable improvement in oxidation resistance, thus highlighting the greater po-tential of Nb-bearing HESAs to function as the elevated-temperature structural materials. The underlying mechanisms for the superior mechanical properties and oxidation resistance of the Nb-bearing HESA were carefully discussed.