A comment on the role of Frank–Read sources in plasticity of nanomaterials

Dislocation generation by a Frank–Read source was considered for the case of nanocrystalline metallic materials. It was shown that thermally activated operation of this mechanism, which was proposed in the literature as an explanation for the observed grain size dependence of the strain rate sensitivity (SRS) of the flow stress, is only possible in a very limited range of the source lengths and stresses. By comparing the calculated SRS with the experimental data for copper, it was further demonstrated that the thermally activated Frank–Read mechanism can be discarded as a process underlying the observed strain rate sensitivity data.