Design of Mg alloys: The effects of Li concentration on the structure and elastic properties in the Mg-Li binary system by first principles calculations

Abstract

First principles calculations have been employed to search for energetically stable structures of the Mg-Li binary system over all possible Mg concentrations. Volume, space group, c/a and b/a ratios, vibrational contribution to the heat capacity, and Debye temperature are reported to investigate the effects of Li concentration on the Mg-Li binary system. Structures of high symmetry and those lying on or close to the convex hull are further explored to search for dynamic and elastic stability. Five ground state structures were found at Li1 Mg13, Li1 Mg2, Li1 Mg1, Li7 Mg2, and Li15 Mg1 compositions. Elastic constants and elastic properties of the selected low energy structures were calculated and analyzed. We also investigate the effect of the phonon band gap found in Li1 Mg1 and Li1 Mg2 on lattice thermal conductivity.