Alloying effects of V on stability, elastic and electronic properties of TiFe₂ via first-principles calculations

The alloying effects of V on structural, elastic and electronic properties of TiFe2 phase were investigated by the first-principles calculations based on the density functional theory. The calculated energy properties including cohesive energy and formation enthalpy indicate V atom would preferentially substitute on 6h sites of Fe atoms in the lattice of TiFe₂ to form the intermetallic Ti₄Fe₇(V). The calculated results of polycrystalline elastic parameters confirm that the plasticity of TiFe₂ would be improved with the addition of V. By discussing the percentage of elastic anisotropy, anisotropy in linear bulk modulus and directional dependence of elastic modulus, it is revealed that the anisotropy of TiFe₂ and Ti₄Fe₇(V) is small. Finally, the density of states, charge density distribution and Mulliken population for TiFe₂ and Ti₄Fe₇(V) were calculated, suggesting there is a mixed bonding with metallic, covalent and ionic nature in TiFe₂ and Ti₄Fe₇(V) compounds. These results also clarify that the reason for the improvement of plasticity with the addition of V in TiFe₂ is the weakened bonding of covalent feature between Ti and V atoms.