Correlation between density of metallic glasses and dynamic fragility of metallic glass-forming liquids

Highlight
• The density evolution correlates with fragility in metallic glasses.
• The density evolution correlates with Poisson's ratio in metallic glasses.
• The density variation reflects structural heterogeneity of metallic glasses.
• The relation among structural heterogeneity and heredity, mechanical behaviors of metallic glass

We study the density evolution upon isothermal annealing far below the glass transition temperature of various metallic glasses (MGs) with different fragilities. We show that the density variation, which reflects the structural heterogeneity of MGs, has correlations with the Poisson's ratio and the kinetic fragility of their supercooled liquid state. The found relationship between the structure heterogeneity of metallic glasses and dynamic heterogeneity of their supercooled liquids has implications for understanding the structural heterogeneity and heredity, mechanical behaviors, and nature of metallic glass.