Screw dislocation interaction with irradiation defect-loops in α-iron: Evaluation of loop-induced stress field effect using dislocation dynamics simulations

摘要

Plastic strain spreading in post-irradiated Fe grains takes the form of wavy shear bands, where mobile dislocations interact with the radiation defect dispersions. In actual Fe grains, dislocation/loop interactions involve several contributing factors including: screw dislocation cross-slip and loop-induced stress. The loop-induced stress effect is here evaluated by systematic simulation case comparisons, using adapted dislocation dynamics simulations. Namely, dislocation/loop simulation cases are systematically compared with equivalent dislocation/facet simulation cases, under room temperature straining conditions. The facets have exactly the same size and orientation as in the reference loop cases, however; the facets have no associated stress field. It is thereby found that in presence of cross-slip the total reaction time and reaction strain associated with various dislocation/facet cases is close to their dislocation/loop counterparts (within 15% and 12%, respectively). In the present investigation context, loop-induced stress field contribution is thus a second order effect, regardless of the considered loop type and orientation. In this situation, the calculation-intensive dislocation/loop interaction description can be replaced by the much faster dislocation/facet approach, for computationally intensive grain-scale simulations.