First-principles thermodynamic calculations of diffusion characteristics of impurities in -iron

Tsuru, Tomohito   ; Kaji, Yoshiyuki  

Since the solute impurities have an effect on the embrittlement through segregation under irradiation, the solute stability of impurity elements is of considerable importance. In the present study, the diffusion characteristics of large-radius impurities in -Fe are investigated by first principles calculations. According to the classical diffusion and transition state theories, diffusion coefficient were evaluated nonempirically. The vacancy formation energy and binding energy between impurity and vacancy were obtained by first principles density functional theory (DFT) calculations. And the migration energy was calculated by nudged elastic band method collaborated with DFT. Consequently, it is confirmed that the binding energy between large-radius impurity and vacancy is larger than that with equivalent size of the solvent element, and that the migration enthalpies of these impurities are quite small compared with self diffusion.