Abstract
In specific conditions, grain-boundary (GB) migration occurs in polycrystalline materials as an alternative vector of plasticity compared to the usual dislocation activity. The shear-coupled GB migration, the expected most efficient GB based mechanism, couples the GB motion to an applied shear stress. Stresses on GB in polycrystalline materials seldom have, however, a unique pure shear component. This work investigates the influence of a normal strain on the shear coupled migration of a GB in a copper bicrystal using atomistic simulations. We show that the yield shear stress inducing the GB migration strongly depends on the applied normal stress. Beyond, the application of a normal stress on this GB qualitatively modifies the GB migration: while the GB shear couples following the migration mode without normal stress, we report the observation of the mode under a sufficiently high tensile normal stress. Using the nudge elastic band method, we uncover the atomistic mechanism of this migration mode and energetically characterize it.
- Received 28 April 2017
- Revised 4 July 2017
DOI:https://doi.org/10.1103/PhysRevMaterials.1.033605
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