First-principles investigation of interaction between surface oxygen and other alloy atoms in α-Ti (0001) for designing high-temperature titanium alloy

The high-temperature titanium alloy faces the dilemma that the oxidation resistance decreases sharply with the increase of temperature. The first-principle calculation has been proved to reveal the antioxidant mechanism from the atomic perspective. Therefore, the changes in Ti-O interaction and oxygen diffusion barrier in α-Ti (0001) crystal plane doped with the alloying elements X have been systematically studied by first-principles calculations. The alloying elements that may improve the oxidation resistance of high-temperature titanium alloy were screened. On this basis, the effect of multi-alloying of Al and screening element Xt on oxygen adsorption and diffusion was further studied. The results show that the adsorption energy depends on the contribution of X-O/Ti-O covalent interaction. Compared with other alloying elements, Nb and Ta can weaken the adsorption of O and hinder the diffusion of surface O to sublayer, which is expected to improve the oxidation resistance of high-temperature titanium alloys. When Al-Ta co-doped, the hindering effects on oxygen adsorption and oxygen diffusion can be superimposed. When both elements are located on the surface, the adsorption and diffusion of oxygen are the most difficult. This work contributes to the rational design of high-temperature titanium alloys.