Oxygen Adsorption, Absorption and Diffusion in FeCrNi Medium Entropy Alloy: An Ab Initio Study.

Despite tremendous efforts to understand interstitial diffusion in bulk alloys, a clear understanding of the principal elemental effect on surface interstitial diffusion is still lacking. In this study, a first-principles approach is employed to study oxygen interstitial diffusion in FeCrNi medium entropy alloy (MEA) based on principal element content at various subsurface sites. Oxygen adsorption energy on surfaces, solution energy at interstitial sites, and activation energy for oxygen permeation are calculated. The adsorption energy for oxygen cohesion to all investigated surfaces was lowest for the sites containing Cr, suggesting a positive effect of Cr in producing a chromium oxide scale. In addition, we have calculated the contribution of the principal element to the stability of the interstitial sites and the activation energy to diffuse between them. This work provides insights into the formation of chromium scaling based on oxygen adsorption and permeation, with potential implications in the design of oxidation-resistant surfaces for high-temperature applications.