Fig.The complex relaxation behaviors of Al90Sm10 metallic glass are predicted by MD-DMS (left) and verified though DMS experiments (right).
(Phys. Rev. Lett. 123, 105701(2019), DOI: https://doi.org/10.1103/PhysRevLett.123.105701)
Background
The complex relaxation dynamics is one of the central topics in numerous areas of glass physics. Even in the structurally simplest metallic glasses, experiments have found many different relaxation behaviors which are far richer than expected. Unfortunately, it’s always very difficult to understand the specific origins of the relaxations and even more challenging to forecast them theoretically. By combining state-of-the-art computer simulation and experiments, this work provides an advance in predicting and understanding the relaxation behaviors in metallic glass.
What we discover?
Relying on the almost one-year-long computer simulations, we find the atomistic models can indeed predict unknown realistic glass relaxation behaviors. As shown in Fig., the MD predict a complex relaxation scenario in the Al90Sm10 MG: at suitably long time scales (e.g., 1µs), it has a pronounced β peak and an anomalous α2 process in addition to the α relaxation. Experiments also observed the predicted relaxation behaviors at a specific temperature regime with the computational guidance. Moreover, the atomistic models revealed surprising origins of these relaxations. Those seemingly unrelated microscopic behaviors, such as the string-like motions where atom jumps one-by-one, or the dynamical disparity where fast and slow atoms moves differently, can be highly correlated to the macroscopic signals of mechanical relaxations.
Why is this important?
The combined experiments (validations) and simulations (predictions and clarification of mechanisms) represent a first glimpse of what may become a routine and integrated step in the study of relaxation processes in glassy physics in the coming future. These new findings broaden the current understanding on the origin of relaxation in metallic glasses. Moreover, it helpful to stimulating for the development of more interaction potentials for the predicting of complex dynamical processes and properties in realistic glasses.
Who did the research?
Yang Sun1, Si-Xu Peng2, Qun Yang2, Feng Zhang1, Meng-Hao Yang1, Cai-Zhuang Wang1, Kai-Ming Ho1, and Hai-Bin Yu2,*
1Ames Laboratory, US Department of Energy and Department of Physics, Iowa State University, Ames, Iowa 50011, USA
2Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
Funding
The work at HUST are supported by National Science Foundation of China (NSFC 51601064) and the Thousands of Young Talent Program. Work at Ames Laboratory was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Science and Engineering Division, under Contract No. DE-AC02-07CH11358, including a grant of computer time at the National Energy Research Supercomputing Center (NERSC) in Berkeley, CA.
