Fan Huiyang, Fan Zhao, Liu Xiongjun, Lu Zhaoping, Ma En
State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing, 100083, China.
Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.
Mater Horiz. 2021 Aug 31;8(9):2359-2372. doi: 10.1039/d1mh00491c.
In a metallic glass (MG), the propensity for atomic rearrangements varies spatially from location to location in the amorphous solid, making the prediction of their likelihood a major challenge. One can attack this problem from the "structure controls properties" standpoint. But all the current structure-centric parameters are mostly based on local atomic packing information limited to short-range order, hence falling short in reliably forecasting how the local region would respond to external stimuli (, temperature and/or stress). Alternatively, one can use indicators informed by physical properties to bridge the static structure on the one hand, and the response of the local configuration on the other. A sub-group of such physics-informed quantities consists of atomic vibration parameters, which will be singled out as the focus of this article. Here we use the CuZr alloy to systematically demonstrate the following two points, all using a single model MG. First, we show in a comprehensive manner the interrelation among common vibrational parameters characterizing the atomic vibrational amplitude and frequency, including the atomic mean square displacement, flexibility volume, participation fraction in the low-frequency vibrational modes and boson peak intensity. Second, we demonstrate that these vibrational parameters fare much better than purely static structural parameters based on local geometrical packing in providing correlation with the propensity for local configurational transitions. These vibrational parameters also share a correlation length similar to that in structural rearrangements induced by external stimuli. This success, however, also poses a challenge, as it remains to be elucidated as to why short-time dynamical (vibrational) behavior at the bottom of the energy basin can be exploited to project the height of the energy barrier for cross-basin activities and in turn the propensity for locally collective atomic rearrangements.
在金属玻璃（MG）中，非晶态固体中原子重排的倾向在空间上因位置而异，这使得预测其可能性成为一项重大挑战。人们可以从“结构决定性能”的角度来解决这个问题。但是，目前所有以结构为中心的参数大多基于限于短程有序的局部原子堆积信息，因此在可靠预测局部区域如何响应外部刺激（如温度和/或应力）方面存在不足。或者，人们可以使用由物理性质提供信息的指标，一方面连接静态结构，另一方面连接局部构型的响应。这类由物理性质提供信息的量的一个子组由原子振动参数组成，本文将专门聚焦于此。在这里，我们使用CuZr合金系统地证明以下两点，所有这些都使用单一的模型金属玻璃。首先，我们全面展示了表征原子振动幅度和频率的常见振动参数之间的相互关系，包括原子均方位移、柔性体积、在低频振动模式中的参与分数和玻色子峰强度。其次，我们证明，与基于局部几何堆积的纯静态结构参数相比，这些振动参数在提供与局部构型转变倾向的相关性方面表现得更好。这些振动参数还具有与外部刺激引起的结构重排相似的关联长度。然而，这一成功也带来了一个挑战，因为仍有待阐明为什么能量盆地底部的短时间动态（振动）行为能够被用来预测跨盆地活动的能量垒高度，进而预测局部集体原子重排的倾向。
