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

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.