First-principles study the structures and mechanical properties of binary W-V alloys

Highlights: • The mechanical properties of the W_1-xV_x alloys are calculated from DFT. • V alloying enhances the ductility of pure W metal substantially. • When the V concentration x reaches 0.25; it can effectively improve the ductility of pure W metal. • The mechanical strength of W-V alloys is slightly weaker than pure W metal while stronger than pure V metal. -- Abstract: The effect of V alloying on the mechanical properties of W-V alloys was investigated by first principles calculation. First of all, we investigated the cell volumes, lattice constants and formation energies of W_1-xV_x (x = 0, 0.0625, 0.125, 0.25, 0.5, 0.75, 0.875, 0.9375 and 1) alloys. Results show that W-V alloys remains bcc structures, and it is an infinite solid solution based on V alloying in the bcc W lattice. These structures of all W-V alloys are thermodynamically stable. Based on the optimized atomic lattices, we investigated the elastic constants of binary W-V alloys. Then we derived the elastic modulus and other related mechanical parameters according to the formulas. It is shown that the mechanical strength of W-V alloys decreases with the increases of V atom concentration. However, the mechanical strength of all alloys is higher than that of pure V metal. On the other hand, the ductility of pure W metal can be improved effectively by V alloying W metal.