Ultra‐stable metallic glass generated by modulation of melt state

Abstract 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.