Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China.
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China.
Nat Commun. 2023 Feb 1;14(1):540. doi: 10.1038/s41467-023-36300-x.
How glasses relax at room temperature is still a great challenge for both experimental and simulation studies due to the extremely long relaxation time-scale. Here, by employing a modified molecular dynamics simulation technique, we extend the quantitative measurement of relaxation process of metallic glasses to room temperature. Both energy relaxation and dynamics, at low temperatures, follow a stretched exponential decay with a characteristic stretching exponent β = 3/7, which is distinct from that of supercooled liquid. Such aging dynamics originates from the release of energy, an intrinsic nature of out-of-equilibrium system, and manifests itself as the elimination of defects through localized atomic strains. This finding is also supported by long-time stress-relaxation experiments of various metallic glasses, confirming its validity and universality. Here, we show that the distinct relaxation mechanism can be regarded as a direct indicator of glass transition from a dynamic perspective.
由于弛豫时间尺度极长，室温下眼镜如何放松仍然是实验和模拟研究的一大挑战。在这里，我们通过采用改进的分子动力学模拟技术，将金属玻璃弛豫过程的定量测量扩展到室温。在低温下，能量弛豫和动力学都遵循具有特征拉伸指数β=3/7 的扩展指数衰减，这与过冷液体不同。这种老化动力学源于能量的释放，这是非平衡系统的固有性质，表现为通过局部原子应变消除缺陷。这一发现也得到了各种金属玻璃的长时间应力松弛实验的支持，证实了其有效性和普遍性。在这里，我们表明，从动力学角度来看，这种独特的弛豫机制可以被视为玻璃转变的直接指标。
