Metastable Phase Selection of an Immiscible Au-W System Studied by ab initio Calculation, Molecular Dynamics Simulation and Ion-Beam Mixing

摘要

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-x)W_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.