报告题目： Atomic Relaxation Process and Physical Aging in Ce-based Bulk Metallic Glasses
陈长玖，中国矿业大学讲师。主要利用中子散射、同步辐射X射线衍射、X射线光子相关光谱等技术，从事非晶合金原子动力学与弛豫过程的相关研究。2017年10月毕业于香港城市大学物理与材料科学系，获哲学博士学位。2017年12月起任职于中国矿业大学材料科学与工程学院。目前已在Applied Physics Letters、Scientific Reports、Journal of Alloys and Compounds等期刊上发表SCI论文13篇, 其中第一作者6篇。
Bulk metallic glasses (BMGs) have attracted much attention in the fields of materials science and engineering due to their considerable scientific importance and potential technological applications. The Ce-based metallic glasses system is a model bulk glass-forming alloy system that shows the enhanced at first and then diminished glass-forming ability (GFA) on increasing the percentage of micro alloying element Co. However, micro alloying does not have any significant impact on the thermodynamic properties. In this study, atomic relaxation dynamics and physical aging of Ce-based BMGs have been investigated by X-Ray Photon Correlation Spectroscopy (XPCS) techniques. In the XPCS studies of Ce-based BMGs, a sharp change of the shape parameter from compressed in the glassy state to stretched in the supercooled liquid indicates that there is a remarkable equilibrium vs out-of-equilibrium dynamical crossover around Tg. In the glassy state, the autocorrelation functions of Ce-based BMGs can be well described by compressed correlation function, which is faster than the exponential correlation function. This compressed behavior arises from ballistic-like motion due to the presence of internal stresses inside the glasses in the out of equilibrium state. The time evolution of the microscopic dynamics during aging is directly captured in XPCS by the intensity of the two-time correlation function. The overall broadening of the two-time correlation function intensity profile reflects a slowing down of the microscopic dynamics corresponding to physical aging. XPCS provides an efficient and practical methodology for investigating the relaxation dynamics and atomic transport mechanism of BMGs.