First-principles studies of Ni–Ta intermetallic compounds

The structural properties, heats of formation, elastic properties, and electronic structures of Ni–Ta intermetallic compounds are investigated in detail based on density functional theory. Our results indicate that all Ni–Ta intermetallic compounds calculated here are mechanically stable except for P21/m-Ni3Ta and hc-NiTa2. Furthermore, we found that Pmmn-Ni3Ta is the ground state stable phase of Ni3Ta polymorphs. The polycrystalline elastic modulus has been deduced by using the Voigt–Reuss–Hill approximation. All Ni–Ta intermetallic compounds in our study, except for NiTa, are ductile materials by corresponding G/K values and poissonʹs ratio. The calculated heats of formation demonstrated that Ni2Ta are thermodynamically unstable. Our results also indicated that all Ni–Ta intermetallic compounds analyzed here are conductors. The density of state demonstrated the structure stability increases with the Ta concentration.