Orientation dependence of elastic properties of Mg binary alloys: A first-principles study

Abstract

To better understand the role of alloying elements on the deformation behavior of Mg, the orientation dependence of elastic properties of Mg was investigated under the influence of solute atoms using first-principles methods. Rare earth (RE) elements (Sc, Y, Gd, Tb, Dy, Ho, Er, Tm, and Lu) and non-RE elements (Ag, Al, Cd, In, Pb, Sn, Tl, and Zn) were studied at the concentration of 2.78 at.%. The three-dimensional representation shape of Young’s modulus (E) shows that the elasticity of pure Mg is anisotropic, which is hardly eliminated by adding 2.78 at.% solid solutes. RE elements would give rise to the spindle-shaped 3D representation of E through increasing the value of E along [0001] direction, which shows the strengthened bonding between basal planes of Mg. Moreover, all RE elements would enhance the value of shear modulus (G) on basal planes; meanwhile, the majority of RE would reduce the local minimum value of G on non-basal planes. In contrast, non-RE elements would exert little influence on the 3D representation shape of E of pure Mg and the value of G on the basal plane. Besides, Cd, In, Sn and Zn would marginally reduce the local minimum value of G on prismatic and pyramidal Ⅱ planes, whereas Ag, Pb, Al, and Tl enhance it. At last, the electron localization function was utilized to analyze the bond strength between planes. This fundamental information would complement the basic knowledge of alloying Mg.