Role of Cr in the high-temperature oxidation behavior of CrxMnFeNi high-entropy alloys at 800 °C in air

Abstract

Oxidation kinetics of different CrxMnFeNi (x = 0.8–1.5) high-entropy alloys (HEAs) at 800 °C in air conformed to parabolic kinetics, and the oxidation resistance first increased and then decreased as the Cr increased. The increase in the Cr content played a dual role: first, Cr promote the formation of a protective and compact oxide layer, which could hinder the diffusion of elements and improve the oxidation resistance; second, Cr promoted the rapid increase of the BCC phase, and the existence of several FCC/BCC phase boundaries enhanced the outward diffusion of the active elements, which could weaken the oxidation resistance.