Defect interaction summary between edge dislocations and <112>-axis symmetric tilt grain boundaries in copper on activation barriers and critical stresses

The interactions between edge dislocations and -axis symmetric tilt grain boundaries (GBs) in copper have been investigated by atomistic simulations. Molecular dynamics simulations and the nudged elastic band method were implemented to investigate the atomistic reaction between the two defects and the activation energy required to trigger such an event in various stress or strain states. The results showed that although different GBs were introduced, the most common scenarios were dislocation absorption into the GB and transmission through the GB. In most cases, the leading partial dislocation was absorbed into the GB once these two crystallographic defects impacted. In contrast, the trailing partial dislocation played a crucial role in determination of the threshold reaction stress. From transition state theory, the reaction energy barriers showed a linear relationship with the resolved shear stress or strain state. The constant activation volume was in the range 22-53b3, where b is the Burgers vector. Furthermore, the corresponding strain rate sensitivities obtained through the activation volumes showed good agreement with the experiment data.