Phase Transformation and Diffusion in High-Temperature Oxidation of Fecrni Medium Entropy Alloy

Abstract

The oxidation of 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 a 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 formation of a discontinuous Cr2O3 layer and penetration of oxide. These observations emphasized the significant roles of phase structure in promoting formation of protective oxide scale and influencing oxidation resistance.

Keywords: Medium entropy alloys (MEAs), Oxidation, Phase transformation, Diffusion, DFT