Ultra-stable metallic glass generated by modulation of melt state

For the development of high-performance metallic glasses, enhancing their stability against viscous flow and crystallization is a primary objective. Vapor deposition or prolonged annealing is an effective method to improve glass stability, shown by increased glass transition temperature (T_g) and crystallization temperature (T_x). This contributes to the development of ultra-stable metallic glasses. Herein, we demonstrate that modulating the quenching temperature can also produce ultra-stable metallic glasses, as evidenced by an increase in T_x of 17–30 K in Cu-based metallic glasses. By modulating the quenching temperature, separated primary phases, secondary phases, and even nano-oxides can be obtained in the metallic glasses. Notably, metastable phases such as Cu-rich precipitates arising from secondary phase separation play a crucial role in enhancing glass stability. However, the enhancement of the stability of the glass has only a negligible effect on its mechanical properties. This study implies that different melt thermodynamic states generated by liquid–liquid separation and transition collectively determine the frozen-in glass structure. The results of this study will be helpful for the development of ultra-stable bulk glasses.