Enhancing dislocation emission in nanocrystalline materials through shear-coupled migration of grain boundaries

A theoretical model has been developed to illustrate the effect of shear-coupled migration of grain boundaries on dislocation emission in nanocrystalline materials. The energy characteristics and critical shear stress tau(c) that is required to initiate the emission process were determined. The results obtained show that the dislocation emission can be considerably enhanced as shear-coupled migration was the dominating process; a critical coupling factor that corresponded to the minimum tau(c), which led to an optimal dislocation emission, was also discovered. The proposed model has also been quantitatively validated by the existing molecular dynamics simulations. (C) 2014 Elsevier B.V. All rights reserved