Impact of sub-Tg thermal cycling on the mechanical properties of CuZr metallic glasses: a molecular dynamics study

The effects of sub-$T_g$ thermal-cycle treatment on the atomistic structure and mechanical properties of Cu₆₄Zr₃₆ metallic glass (MG) were studied using molecular dynamic simulations. The MG sample was prepared by rapidly quenching to 100 K with different rates, and then subjected to thermal cycling between 100 K and 600 K. The sub-$T_g$ thermal cycling leads to a decrease in potential energy for samples quenched with higher rates, indicating that the amorphous structural state has been altered while it remains same for samples quenched with slower rates. It was found that both tensile and shear strength increase due to thermal cycles. Creep simulations revealed a significant enhancement in creep resistance due to thermal cycles, particularly for samples quenched with higher rates. Furthermore, an increasing fraction of icosahedral clusters was observed during thermal cycles for sample quenched at higher rates. The activation energy distribution was found to shift towards higher values after thermal cycling, indicating a more stable atomic configuration and greater resistance to deformation. These findings highlight the profound impact of sub-$T_g$ thermal cycling on the structural and mechanical behaviours of MGs.