Investigation of atomic diffusion at Ni/Zr₄₈Cu₃₆Ag₈Al₈ interfaces in the glass transition temperature

Poor plasticity and small dimension are the main disadvantages of metallic glass. Diffusion bonding and composite fabrication between bulk metallic glasses (BMGs) and crystal metal are promising methods of addressing these disadvantages. In this study, the long-term atomic diffusion behavior in the glass transition temperature (T_g) is investigated to avoid the formation of the crystalline phase at the interface. Diffusion-coupled Ni/Zr₄₈Cu₃₆Ag₈Al₈ BMG is successfully fabricated by sputtering deposition. The diffusivities of Ni in Zr₄₈Cu₃₆Ag₈Al₈ metallic glass are calculated by using the thin-film solution of Fick's second law. The diffusivities of Ni in Zr₄₈Cu₃₆Ag₈Al₈ alloy are functions of annealing temperature and time because of the dominant effect of the free volume. High-resolution transmission electron microscopy results show that there are no crystals formed at the interface of diffusion-coupled Ni/Zr₄₈Cu₃₆Ag₈Al₈ BMG below T_g, and mutual element diffusion occurs near the interface. Analysis of the diffusion behavior and microstructure indicates that the long-term annealing below T_g can be applied to the diffusion bonding of BMG and crystal metal.