Structural, Elastic, Mechanical and Electronic Properties of NbW-Based Intermetallic Compounds: First-Principles Calculations

The structural, elastic and electronic properties of NbW-based intermetallic compounds have been investigated by first-principles calculations from CASTEP code based on density functional theory (DFT). The calculated lattice parameters of NbW-based intermetallic compounds are in good agreement with the experimental values. The calculated elastic constants indicate that NbW, CNb_0.8W_0.2, Mo_0.333Nb_0.333W_0.333, Nb_0.33Ta_0.33W_0.34, Nb_0.75Se₂W_0.25, and Nb_2.25S₆W_0.75 have mechanically stable structures. The bulk modulus, shear modulus, Young's modulus, and Poisson's ratio are obtained. With the addition of Ta element, the ductility of NbW-based alloys increases obviously. With the addition of non-metallic elements, it can be decreased. Among the six compounds, Nb_0.33Ta_0.33W_0.34 has the best plasticity and the stiffness of CNb_0.8W_0.2 is the highest. The results show that NbW, Mo_0.333Nb_0.333W_0.333, Nb_0.33Ta_0.33W_0.34, and Nb_2.25S₆W_0.75 are ductile, and CNb_0.8W_0.2 as well as Nb_0.75Se₂W_0.25 are brittle. Furthermore, all NbW-based intermetallic compounds considered in this work are conductors.