Effect of the local chemical environment on oxidation resistance mechanisms in AlNbTiZr refractory high entropy alloys: A first-principles study

The present study is dedicated to the effect of local chemical environment on structure and properties of oxygen adsorption on AlNbTiZr surface from first-principle investigation. The adsorption energy results illustrate that the most stable adsorption sites are those with high content Ti, mainly due to its highest t2g states near Fermi level. The stronger O-Al than O-Ti interaction will cause outward diffusion of Al, which explains the high concentration Al in oxide layer of AlNbTiZr experimentally. More importantly, Ti atom weakens the O-Al interaction, and thereby may weaken the stability of Al-containing oxides. Consequently, it is necessary to control experimentally by different processing methods to decrease the occurrence of Ti-Ti arrangement on the surface to improve oxidation resistance of AlNbTiZr.