Phase transformation and diffusion in high-temperature oxidation of FeCrNi medium entropy alloy

Abstract

The oxidation of the FeCrNi medium entropy alloy is investigated from 700 to 1000 °C by combining experimental observations with density functional theory (DFT) calculations. The sole oxidation product formed is Cr2O3. At 900 °C, the layer exhibits desirable density and continuity, attributed to the rapid diffusion of Cr facilitated by the body-centered cubic phase transformation. There is a significant increase in mass gain rates at 1000 °C, accompanied by the formation of a discontinuous Cr2O3 layer and penetration of oxide. These observations emphasize the significant roles of phase structure in promoting the formation of protective oxide scales and influencing oxidation resistance.