First-principles study of diffusion coefficients of alloy elements in dilute Mg alloys

The equilibrium thermodynamic properties of Mg alloys are reasonably well understood, but the kinetics of these alloys is explored to a far lesser extent, especially diffusion coefficients of alloying elements in Mg. In the present work, first-principles calculations based on the Density Functional Theory (DFT) were used to calculate the dilute tracer diffusion coefficients in Mg for 61 elements, including rare earths, as a function of temperature using an 8-frequency model. An improved generalized gradient approximation of PBEsol was used in the present work, which is able to well describe both vacancy formation energies and vibrational properties. Systematic trends of diffusion activation energies of various solutes were analyzed. Remarkable agreements of the calculated results compared with available experimental data were obtained.