Grain boundary migration in nanocrystalline Ni under constant shear strains and its mechanism

XH Yang and J Li and P Wang, COMPUTATIONAL MATERIALS SCIENCE, 176, 109530 (2020).

DOI: 10.1016/j.commatsci.2020.109530

The grain boundary (GB) migration behavior of nanocrystalline Ni during shear dwelling was simulated using the molecular dynamics method. It was found that further GB migration could take place and be completed within a very short period of time when the external shear load is kept unchanged. The atomic shear stress redistribution was demonstrated to be the driving force. Both the dwelling strain and temperature have considerable complicated influences on the further GB migration. The local atomic shear stress difference around the GB was proposed to characterize the unevenness of atomic shear stress. A threshold condition was given in terms of the local atomic shear stress difference, namely only when it is larger than its threshold value would the further GB migration occur. The threshold value was quantitatively related to the temperature. The effects of dwelling strain and temperature on the further GB migration can be well explained.

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