Static atomic-scale structural heterogeneity and its effects on glass formation and dynamics of metallic glasses

Molecular dynamics simulations were employed to investigate structural heterogeneity at the sub-nanometer scale for binary Cu-Zr liquids and glasses. The normalized local atomic number density fluctuates significantly in all the liquids and glasses, confirming existence of the static atomic-scale structural heterogeneity. The dynamic evolution of structural heterogeneity profile shows that the good glass former has better inheritance of structural heterogeneity from its liquid state than the poor one, suggesting a close relation between the structural inheritance and the glass-forming ability. Further analyses regarding evolution of dynamic properties, i.e., viscosity and the α relaxation time, as a function of undercooling demonstrate that the better inheritance of the structural heterogeneity in the better glass former stems from its higher liquid stability. Our atomic structural investigation indicates that the enhanced connectivity of short-range ordering clusters could be responsible for the better inheritance of structural heterogeneity and the larger glass-forming ability.