Abstract
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.
Highlights
High-pressure treatment of metallic glasses has received significant scientific attention
We primarily focused on studying a high-pressure heat-treated bulk sample by rapid cooling, with the aim of obtaining a sample frozen in the high-pressure/temperature glassy state at room temperature
The high-pressure heat-treated (5.5 GPa at 850 K) state of a Zr50Cu40Al10 metallic glass was successfully obtained by rapidly cooling a bulk sample from slightly below Tx
Summary
High-pressure treatment of metallic glasses has received significant scientific attention. Polymorphic transition induced by pressure has been observed in many metallic glass systems[1,2,3,4,5]. In molecular dynamic (MD) simulation studies, polymorphic transitions and the creation of new types of abnormal glass through high-pressure heat treatment was predicted (i.e., a high-energy but high-density and well-ordered glass[7,8]). There have been attempts to explain these types of transitions and phenomena using many theoretical models (e.g., 4f electron delocalization[1,2,3,4,5], P- and N-type free volume[8,9], and a two-order-parameter model[10,11]).
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