First-principles study of structural, mechanical, and electronic properties of W alloying with Zr

The structural, mechanical and electronic properties of W_1-xZr_x (x=0.0625, 0.125, 0.1875, 0.25, 0.5) are systematically investigated by means of first-principles calculation. The total-energy calculations demonstrate that the W-Zr binary substitutional solid solution remaining bcc structure can be formed at an atom level. In addition, the derived bulk modulus (B), shear modulus (G), Young's modulus (E) for each of W-Zr alloys decrease gradually with the increase of Zr concentration, suggesting that W alloying with higher Zr concentration becomes softer than pure W metal. Based on the mechanical characteristic B/G ratio, Poisson's ratio ϒ and Cauchy pressure C', all W_1-xZr_x alloys are regarded as ductile materials. The ductility for each of those materials is improved with the increase of Zr concentration. The calculated density of states indicates that the ductility of W_1-xZr_x is due to the fact that the bonding in the alloy becomes more metallic through increasing the Zr concentration in tungsten. These results provide incontrovertible evidence for the fact that Zr has a significant influence on the properties of W.