A first principles investigation on the influence of transition-metal elements on the structural, mechanical, and anisotropic properties of CaM2Al20 intermetallics

Abstract

The anisotropy in elasticity, mechanical properties and electronic properties of CaM₂Al₂₀ (M = V, Nb, Cr, Ti, Mo and Ta) compounds were investigated using the first-principle calculations. These ternary compounds are structurally stable according to the obtained phonon frequencies and formation enthalpy. The results of elastic modulus, hardness and elastic constants explain that CaM₂Al₂₀ intermetallics have higher hardness and better resistance to deformation change than pure aluminum. Poisson's ratio and the values of B/G confirm that CaTi₂Al₂₀, CaV₂Al₂₀, CaCr₂Al₂₀, CaNb₂Al₂₀ and CaTa₂Al₂₀ are brittle materials, but CaMo₂Al₂₀ is ductile material. The 3D surfaces of Young's modulus and anisotropic constants confirm that CaMo₂Al₂₀ and CaTi₂Al₂₀ have the larger anisotropy than other four compounds. What's more, the density of states and charge density differences of CaM₂Al₂₀ compounds explain the mechanism of the structural stability and mechanical properties.

Keywords: Anisotropic properties; CaM(2)Al(20) intermetallics; Elastic properties; Electronic properties.