β-relaxation of the nanoglass and metallic glass.
(Nano Letters 2021, 21, 14, 6051–6056)
Background
Glass is a disordered solid that lacks long-range order in the structure and is in a thermodynamically non-equilibrium state in energy, so relaxation is its essential feature. Complex relaxation processes are shown in different time-scales and temperature ranges for metallic glasses, such as α relaxation, β relaxation and boson peak. Among the many relaxation processes of metallic glasses, the β relaxation process in the glass state has become the focus of relaxation researchers, because it is closely related to many important properties of metallic glasses. However, one puzzling feature for β-relaxations is that they are relatively insensitive to physical processing and thus not easily modified without changing the chemical composition for most glassy materials.So far, we have not directly observed the microstructure characteristics corresponding to β relaxation in experiments. The main reason is that structural modulation without involving changes in chemical composition is not only difficult to observed and characterized, but also cannot significantly change its relaxation behavior to a large extent, such as annealing and rejuvenation. It is still a main challenge to modify the observable microstructure of metallic glass to modulate its relaxation behavior, without involving changes in chemical composition.
What did we discover?
In this study, taking metallic nanoglasses with obvious observable structural characteristics as the research material, we have studied the structure-dynamic relationship of metallic nanoglasses in a comparative form, and examined the relationship between relaxation behaviors and mechanical properties. Our results show that metallic nanoglass with obvious amorphous interfaces (glass-glass interfaces) have more obvious β relaxation peaks and microscopic tensile plastic deformation ability than ordinary melt-quenched metallic glass. In addition, the microstructure of nanoglass was modulated by annealing treatment, and we further verified the structure-dynamics relationship in metallic glasses by monitoring the evolution of its β relaxation peak.
Why is this important?
Our current results provide clear evidence for the correlation between the microstructure and the β relaxation in metallic glasses. At the same time, our results indicate that nanostructuring of the glass structure is also a generally applicable and effective approach to promote β relaxations in metallic glasses, which could be utilized in the tuning of properties, such as the ductility of metallic glasses. More importantly, the metallic nanoglass is in a high-energy state compared to ultrastable glass in an ultra-low-energy state. This provides an opportunity to study the relationship between relaxation, properties, and structure in metallic glasses with an ultrawide range of possible states.
Who did the research?
Qun Yang,1,∗ Chao-Qun Pei,2,∗ Hai-Bin Yu,1,† and Tao Feng2,‡
1Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, WuHan 430074, China.
2Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, 200 Xiaolingwei Avenue, Nanjing 210094, China.
†Corresponding authors. Emails:haibinyu@hust.edu.cn; tao.feng@njust.edu.cn
https://pubs.acs.org/doi/10.1021/acs.nanolett.1c01283
