Atypical three-stage-hardening mechanical behavior of Cu single-crystal micropillars

Three-dimensional discrete dislocation dynamics simulations have been used to study the stress–strain response of Cu single-crystal micropillars containing initial dislocation networks. When such networks are loaded, we find that the stress–strain curve can be divided into three distinct stages: a linear elastic stage, a normal strain hardening stage and a “dislocation starvation hardening” stage accompanying a rather high stress level. Finally, a perfect dislocation-free pillar is obtained in our simulations.