Metastable phase selection of an immiscible Au-W system studied by ab initio calculation, molecular dynamics simulation and ion-beam mixing

With the aid of ab initio calculation, the lattice constants and cohesive energies of some ordered metastable Au-W compounds are calculated and used in deriving an n-body Au-W potential under the embedded atom method. On the basis of the proven realistic Au-W potential, molecular dynamics simulations predict the phase selection over the entire composition: the metastable Au _100-xW_x phase in an fcc structure is more stable than in a bcc structure when 0 ≤ x ≤ 43, whereas the bcc structure becomes energetically favored when 43 < x < 100. The prediction is in good agreement with the results obtained from ion-beam mixing experiments, i.e., the bcc and fcc solid solutions are formed in the W-enriched and Au-enriched sides, respectively.