发表机构
Institute of Frontier Materials on Earth and in Space, German Aerospace Center; Institut Néel, Université Grenoble Alpes and Centre National de la Recherche Scientifique; European Synchrotron Radiation Facility; Institute for Condensed Matter Physics, Technical University of Darmstadt; Department of Physics, Institute of Energy Technologies, Universitat Politècnica de Catalunya—BarcelonaTech（地球与太空前沿材料研究所，德国航空航天中心; 内尔研究所，格勒诺布尔阿尔卑斯大学及法国国家科学研究中心; 欧洲同步辐射装置; 凝聚态物理研究所，达姆施塔特工业大学; 物理系，能源技术研究所，加泰罗尼亚理工大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过同步X射线衍射与光子相关光谱实验，发现金属玻璃的微观动力学不遵循材料时间标度，但材料时间仍可描述其平均结构演化。
AI 中文摘要
玻璃的物理老化通常用材料时间的概念来描述，该概念假设其潜在的弛豫机制与平衡态下相同，但速率在老化过程中发生变化。材料时间是否也能描述金属玻璃的微观动力学尚不清楚，因为金属玻璃在玻璃态与平衡过冷液体之间的微观动力学存在质的差异。利用同步时间分辨X射线衍射和X射线光子相关光谱，我们追踪了金属玻璃在从平衡态出发的小温度跳变后的完全平衡过程。第一尖锐衍射峰位置的时间演化表现出温度上跳与下跳之间的不对称性，这是材料时间老化的特征，并可由基于该概念的Tool-Narayanaswamy-Moynihan模型定量描述。相比之下，微观密度-密度自相关函数强烈违反材料时间标度。即使温度变化小至4K，无论温度跳变方向如何，都会出现压缩指数弛豫，并随着平均结构的平衡而连续演变为拉伸指数弛豫形状。这种行为与体积挫折相关的瞬态应力介导贡献一致，该贡献在平衡后消失。我们的结果表明，即使相应的微观动力学不遵循材料时间标度，材料时间也能描述平均结构性质的演化。
英文摘要
Physical aging in glasses is often described using the concept of material time, which assumes the underlying relaxation mechanism to remain the same as in equilibrium, but with a rate that changes during aging. Whether material time also captures the microscopic dynamics of metallic glasses, which differ qualitatively between the glass and the equilibrium supercooled liquid, is unclear. Using simultaneous time-resolved X-ray diffraction and X-ray photon-correlation spectroscopy, we follow the full equilibration of a metallic glass after small temperature jumps starting from equilibrium. The time evolution of the first sharp diffraction peak position exhibits the asymmetry between temperature up- and down-jumps characteristic of material-time aging and is quantitatively described by the Tool-Narayanaswamy-Moynihan model, which is based on this concept. By contrast, the microscopic density-density autocorrelation functions strongly violate material-time scaling. Compressed-exponential relaxation emerges even after temperature changes as small as 4K, irrespective of the direction of the temperature jump, and continuously evolves into a stretched-exponential relaxation shape following the equilibration of the average structure. This behavior is consistent with a transient stress-mediated contribution associated with volumetric frustration that disappears upon equilibration. Our results show that a material time can describe the evolution of average structural properties even when the corresponding microscopic dynamics do not obey material-time scaling.
