Ti-X (X=Al, V, Nb, Ta, Mo, Zr, and Sn) impurity diffusion coefficients from first-principles calculations

Abstract

Knowledge of diffusivity is fundamental to our understanding of diffusion mechanism and design of materials. Despite various elements dissolved in industrial Ti alloys to improve their performance, diffusion coefficients of alloying elements in Ti, especially in α-Ti with the hcp structure, are largely unknown due to numerous daunting experimental difficulties. Based on first-principles calculations in terms of transition state theory and an 8-frequency model, we report diffusion coefficients of substitutional alloying elements X in dilute α-Ti alloys, where X denotes Al, V, Nb, Ta, Mo, Zr, and Sn. It is shown that the calculated self- and solute diffusion coefficients in dilute α-Ti agree well with measurements where available.