First-principles study of the phase stability and the mechanical properties of W-Ta and W-Re alloys.

The phase stability and mechanical properties of binary W_1-xTa_x and W_1-xRe_x alloys were investigated using the full-potential augmented plane-wave method. The special quasirandom structures(SQSs) of these alloys aremechanically stable due to all of the positive elastic constants and negative binding energies. The binding energies of both the W_1-xTa_x and W_1-xRe_x alloys also exhibit energy favorable asymmetry toward the W-rich side. In addition, the bulk modulus of the W_1-xTa_x alloys decrease gradually with the increase of the Ta concentration, while those of the W_1-xRe_x alloys increase gradually with the increase of the Re concentration. Consequently, the bulk modulus of W metal can be improved by doping with Re, implying that the resistance to deformation is enhanced. Based on the mechanical characteristic G/B and Poisson's ratio v, both the W_1-xTa_x andW_1-xRe_x alloys are regarded as being ductile materials, the ductility of which improves with the increase of Ta or Re. [ABSTRACT FROM AUTHOR]