Evolution of dislocation patterns in a tricrystal model subjected to cyclic loading

摘要

When a polycrystalline aggregate is deformed beyond the elastic range, dislocations pile up at grain boundaries and make some patterned structures within the grains. If the external load is reversed, most dislocations at grain boundaries and in the patterned structure are supposed to disappear or change their arrangements, but the details are not yet well known. In this study, we examined such changes in dislocation structures by a crystal plasticity analysis. Models for the polycrystalline aggregates consist of three grains and the generation and degeneration of the geometrically necessary dislocations during cyclic loading are examined in detail. The results show that there are some groups of dislocations that do not dissipate but evolve upon reverse loading.