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 appro ximation have been employed to study the ground-state properties of the ter nary intermetallic Ti2AlNb (O phase). The equilibrium volume, cohesive ener gy, formation energy, and bulk modulus are obtained. The results calculated compare well with the available experimental results. The densities of sta tes and charge-density plots show that the bonding in Ti2AlNb is metallic i n nature and has a more covalent bond than in Ti3Al. It is found that Nb at oms decrease the covalent bonding around themselves locally and increase th e degree of directional bonding between Ti and Al, which may explain why Ti 2AlNb (O phase) enjoys better ductility and fracture toughness than Ti3Al.