Microscopic glass-transition in Ni-based metallic glass-forming melts

Quasielastic neutron scattering (QENS) has been used to investigate microscopic dynamics in the glass-forming Ni80P20, Pd40Ni40P20 and Pd43Ni10Cu27P20 melts. These melts are characterized by a high-packing fraction that is similar at their liquidus temperatures. Increasing the number of components in these melts increases the viscosity at their liquidus temperature. However, the fragility of these melts did not show a composition dependence. Atomic dynamics in these liquids agree well with mode-coupling theory (MCT) predictions. From the MCT analysis of the QENS data the critical packing fractions for the microscopic glass-transition (ϕc) were obtained. The values obtained for ϕc are well within the MCT theoretical predictions for hard-sphere liquids