First-principles study the phase stability and mechanical properties of binary W-Mo alloys

Based on the first principles calculations, the effect of Mo alloying on the mechanical properties of W-Mo alloys was investigated. First of all, we calculated the lattice constants, the cell volumes and the formation energies of W1-xMox (x = 0, 0.0625, 0.125, 0.25, 0.5, 0.75, 0.875, 0.9375 and 1) alloys. Results show that W-Mo alloys remains bcc structures, and Mo alloying in bcc W lattice is an infinite solid solution. All the structures of W-Mo alloys are thermodynamically stable. Based on the optimized atomic lattices, we calculated the elastic constants of binary W-Mo alloys, and then derived the elastic modulus and other mechanical parameters. Results show that although the mechanical strength of W-Mo alloys is lower than that of pure W metal, it is much higher than that of pure Mo metal. On the other hand, by analyzing the mechanical parameters B/G ratio and Poisson's ratio of W-Mo alloys, Mo alloying can improve the ductility of pure W metal obviously.