Observation of distinct atomic relaxation process in a phase-separated metallic glass-forming melt

We have investigated the atomic relaxation processes in phase-separated alloy melts using quasielastic neutron scattering. Among the three alloy melts studied (i. e., Al30Cu20Sn50, Al30Cu30Sn40 and Y28Ti28Al24Co20), Y28Ti28Al24Co20 is not only a phase-separated melt but also vitrified upon quenching. In this glass-forming melt, we have observed dissimilar relaxation processes in the different phases of the melt: a collective atomic transport process in the phase that exhibits a slow relaxation process and an atomic jump diffusion process in the phase that displays a fast relaxation process. Interestingly, the temperature dependence of the diffusion process in the former phase is a non-Arrhenius process, which is similar to that observed in many fragile glassforming liquids. In contrast, the temperature dependence of the diffusion process is an Arrhenius process in the later phase, which is a characteristic of non-glass-forming simple liquids. Copyright c (C) EPLA, 2014