Thermally activated dislocation depinning at a grain boundary in nanocrystalline and ultrafine-grained materials

As an attempt to understand the temperature and strain-rate dependence of strength in nanocrystalline and ultrafine-grained materials, thermally activated depinning process has been incorporated into a dislocation bow-out model from a grain boundary. Such quantities as activation energy, activation volume, strain-rate sensitivity and yield strength are discussed and compared with experimental results available in literature. It is found that the present model analysis can reasonably explain the observed characteristics of these quantities.