The structural sign of dynamic crossover in CuZrAl metal glass

Abstract Molecular dynamics simulations of Cu48Zr48Al4 metallic glass reveal a direct link between dynamic crossover behavior and medium-range order (MRO) evolution during cooling. The system undergoes a distinct dynamic transition at 1300 K (1.9Tg), marked by a shift from Arrhenius to non-Arrhenius atomic diffusion and pronounced splitting in the second peaks of partial radial distribution functions (Cu-Cu, Cu-Zr, Zr-Zr). Quantitative analysis using a newly developed radial distribution function (RDF) area difference metric shows that this crossover coincides with accelerated MRO formation, particularly within Cu-Cu and Cu-Zr coordination shells. These results provide structural evidence connecting the dynamic anomaly to MRO domain development, resolving long-standing debates about the structural origin of dynamic crossovers in metallic glasses.