Structural stability and characteristics of the metastable Ag–W phases studied byab initioand molecular dynamics calculations

For the immiscible Ag–W system, ab initio calculations identify the relatively stable structures of the metastable ${\mathrm{Ag}}_{75}{\mathrm{W}}_{25}$ , AgW, and ${\mathrm{Ag}}_{25}{\mathrm{W}}_{75}$ phases to be $L{6}_0$ , $B2$ , and $L{1}_2$ , respectively. Based on a newly derived Ag–W potential under an extended Finnis-Sinclair formalism, molecular static and dynamics calculations predict that for the ${\mathrm{Ag}}_{100-x}{\mathrm{W}}_x$ alloy, a bcc structure is more stable than a fcc one when $80<x⩽100$ , and that bcc and fcc structures have almost similar formation energies when $0⩽x<80$ . Moreover, molecular dynamics simulations show that an amorphous state has lower formation energy than its fcc or bcc counterpart in a composition range of $20⩽x⩽80$ , which is therefore the glass-forming ability/range of the Ag–W system. Interestingly, moderate phase segregation is observed in the Ag–W amorphous alloy upon simulations, and the segregation tendency is found to strongly depend on the alloy composition as well as on the temperature.