Comparative study of metastable phase formation in the immiscible Cu-W system by ab initio calculation and n-body potential

The lattice constants and cohesive energies of some possible metastable Cu-W compounds are obtained by ab initio calculation and the formation of a metastable phase at Cu75W25 is predicted for the equilibrium immiscible Cu-W system. The prediction is in agreement with the fact that a metastable hcp phase was indeed observed in the Cu75W25 multilayer films upon ion beam mixing. Furthermore, some of the ab initio calculated properties are used in deriving an n-body Cu-W potential under the embedded atom method. The constructed Cu-W potential is then used to predict the phase stability of the metastable Cu-W phases over the entire composition and the prediction is also supported by some experimental observations.