Effect of alloying elements on the elastic properties of Mg from first-principles calculations

The influence of different alloying elements on the lattice parameters and elastic properties of Mg solid solution has been studied using first-principles calculations within the generalized gradient approximation. The solute atoms employed herein are Al, Ba, Ca, Cu, Ge, K, Li, Ni, Pb, Si, Y and Zn. A supercell consisting of 35 atoms of Mg and one solute atom is used in the current calculations. A good agreement between calculated and available experimental data is obtained. Lattice parameters of Mg–X alloys are found to be dependent on the atomic radii of the solute atoms. A correlation between the bulk modulus of Mg–X alloys and the nearest-neighbor distance between Mg and X is shown. Addition of solute atoms belonging to the s-block and p-block of the periodic table results in a lower bulk moduli than d-block elements. A strong dependence of the elastic modulus of Mg–X alloys on the elastic properties of the solute atoms is also observed. Using the bulk modulus/shear modulus ratio (B/G), the change in the ductility of Mg due to the addition of the solute atom is briefly described. Linear regression coefficients for the elastic constants of each of the alloys are obtained as a tool for predicting the trend in the elastic properties of Mg as a function of concentration of the solute atoms.