The influence of short-range structures on atomic caging in glass-forming Cu-Zr-Al melts

Atomic caging is an important dynamic process that influences liquid vitrification. In this article, we have studied bulk glass-forming copper-zirconium-aluminum (Cu-Zr-Al) systems using quasielastic neutron scattering and molecular dynamics simulation in order to understand the influence of short-range structures on atomic caging. We found that, in Cu-Zr-Al melts, the long-range atomic transport process occurs via a jump-diffusion process, and temperature dependence of the atomic diffusion process is non-Arrhenius. Furthermore, the Cu diffusion coefficient at a given temperature decreases with Al addition. Inherent structures obtained from molecular dynamics simulation trajectories show that the dominant short-range structures above the melting temperature of these melts are ⟨0,3,6,4⟩ and ⟨0,2,8,2⟩ and the percentage of these structure increases with decreasing temperature. The residence time of the atoms in the cage was found to be directly correlated with the number of dominant short-range structures in these melts. Our results show that transient local short-range structures have a strong influence on atomic caging in the glass-forming metallic melts.