J-Integral Evaluation of Continuous Dislocation Emissions from the Crack Tip near Grain Boundaries in Atomic Simulations

Abstract

Extrinsic grain boundary dislocations (EGBDs) are often observed in ultra fine-grained metals produced by severe plastic deformation processes. The mechanical properties of such metals are different from those of coarse-grained metals, so EGBDs could be important factor to elucidate the unique mechanical properties. In this paper, in order to clarify the influence of EGBDs on the emission of dislocations from the crack tip, we evaluate the mechanical field around the crack tip using J-integral in atomic simulations. It is found that quantitative evaluations of the crack-tip shielding effect due to EGBDs can be performed by J-integral taking grain boundary structures into account.