Thermodynamic assessment of the Ti–Al–Zr system and atomic mobility of its bcc phase

Abstract

In the present work, the thermodynamic description of the Ti–Al–Zr ternary system was assessed by taking into account the ab initio data on the formation enthalpies of end-members of the intermetallic compounds, combined with the available experimental phase equilibria information in literature. The developed thermodynamic description of Ti–Al–Zr system allows to reasonably represent the experimental phase relations, and particularly to describe the solubility of third element in the binary intermetallic compounds well. Upon the newly developed thermodynamic description, the atomic mobility parameters of the bcc_A2 phase for the Al–Zr binary and Ti–Al–Zr ternary were synergistically assessed to fit the experimental diffusion data in literature. The developed atomic mobility enables to reliably derive all types of reportedly diffusion coefficients in literature. The comprehensive comparison made between the model-predicted and diffusion experiments with emphasis on composition profiles and diffusion paths confirms the reliability of the atomic mobility developed in this work.