Interface-driven solid-state alloying in an immiscible Cu-W system

Cu-W multilayered films were properly designed according to an interfacial free-energy estimation such that an amorphous and three metastable crystalline FCC phases were formed by solid-state reaction in this immiscible system. To understand such alloying behaviour, a Gibbs free-energy diagram of the system was constructed on the basis of Miedema's model and related methods. The calculated diagram showed that the interfacial free energy resulting from chemical and elastic contributions could raise the initial energetic state of the multilayered films to a state higher than those of the observed metastable phases, thus providing a driving force for solid-state alloying in this immiscible Cu-W system.