Energetics of point defect interacting with grain boundaries undergone plastic deformations

Abstract

Grain boundaries (GBs) in the polycrystalline and nanocrystalline materials are usually at their non-equilibrated states due to the plastic deformations. Thus, the point defect sink efficiencies of non-equilibrated GBs may be different from those of equilibrated counterparts, which may influence the irradiation tolerance of materials. In this paper, we firstly performed the shear responses of four copper symmetric tilt grain boundaries (GBs). The plastic deformation modes of four GBs include GB sliding, shear-coupling and complex mechanism due to atom-shuffling, partial dislocation nucleation and local GB dissociations. We then study the energetics of point defects interacting with a series of GB configurations undergone plastic deformations. It is found that the plastic deformation dominated by the sliding and shear-coupling has no effect on the point defect sink efficiency of GB in comparison with initial GB states. However, sink efficiencies of GB configurations produced from the complex deformation mode are generally intensified, for both vacancy and self-interstitial atom. In addition, the residual stress in the crystals due to the dislocation nucleating from GB affects the point defect concentration in the crystals. On the other hand, complex deformation mechanism drives GBs to higher energy states with highly disordered structures. As a result, the distribution of lower point defect formation energies extends a larger distance from GB, which may therefore favor GB absorbing the point defects nearby.