Electronic structure of Ti2AlNb (O phase)

First-principles calculations based on the total-energy, all-electron, full-potential linear muffin-tin orbitals method within the local-density approximation have been employed to study the ground-state properties of the ternary intermetallic Ti2AlNb (O phase). The equilibrium volume, cohesive energy, formation energy, and bulk modulus are obtained. The results calculated compare well with the available experimental results. The densities of states and charge-density plots show that the bonding in Ti2AlNb is metallic in nature and has a more covalent bond than in Ti3Al. It is found that Nb atoms decrease the covalent bonding around themselves locally and increase the degree of directional bonding between Ti and Al, which may explain why Ti2AlNb (O phase) enjoys better ductility and fracture toughness than Ti3Al.