High pressure reshapes the sub-Tg aging pathway of a metallic glass: decoupling between structural ordering and energy and reduced strain localization

Abstract

The aging pathways of metallic glasses below the glass transition temperature are strongly influenced by pressure. However, the relationship between annealing pressure and microstructure remains unclear. How the energy carried by different local structures changes is also poorly understood. Here, molecular dynamics simulations were performed to investigate the annealing of Zr50Cu40Al10 metallic glass at 700 K under pressures of 0–10 GPa. The post-annealing structure, energy, and tensile response were subsequently examined. The results show that increasing pressure suppressed atomic migration but promoted the accumulation of Cu-centered full icosahedral clusters (ICOs). After pressure release, changes in the potential energy of the annealed samples exhibited pronounced element specificity and structural selectivity. Relative to the 0 GPa sample, Zr atoms accounted for most of the increase in potential energy. In contrast, Cu and Al atoms exhibited pronounced region-dependent behavior, with the ICO regions showing a marked increase in potential energy. Meanwhile, increasing pressure raised the number of ICOs in the final samples. However, tensile simulations revealed a lower yield stress, a higher net loss fraction of ICOs, and a transition from a continuous shear band to a more diffuse strain-field distribution. These results indicate that an increased ICO population does not necessarily lead to higher strength. The mechanical response of metallic glasses also depends on the dynamic stability of ICOs. Together, these findings reveal a decoupling among structural ordering, energy accommodation, and mechanical response during pressure-controlled aging. This study provides a microscopic theoretical basis for understanding pressure-path effects and structure–property design in metallic glasses.