Unveiling a new type of ultradense anomalous metallic glass with improved strength and ductility through a high-pressure heat treatment

An anomalous glass was discovered through high-pressure heat treatment (5.5 GPa at 850 K) followed by rapid cooling of a Zr₅₀Cu₄₀Al₁₀ metallic glass. Despite a reduction in the crystallization temperature and enthalpy, high-resolution transmission electron microscopy analysis revealed that the collected bulk sample maintained a fully amorphous structure. The density of the sample was 0.6% larger than that of the as-cast state and was even larger than that of the partially crystallized state. These results suggest the formation of an ultradense packing glass that cannot be obtained through conventional annealing. Compression test results indicated a significant increase in the Young’s modulus and fracture strength, supporting the creation of an anomalous metallic glass. In addition, plasticity was observed in the treated sample. It was therefore concluded that the high-pressure heat treatment enabled the creation of a new type of glass that is normally overshadowed by the crystallized phase at atmospheric pressure. We explained the creation of the ultradense glass by introducing a pressure parameter (P) to the conventional volume (v) - temperature (T) diagram.