Dynamics of defect-loaded grain boundary under shear deformation in alpha iron

Two symmetric tilt grain boundaries (GBs) (Sigma 3 < 110 > {112} and Sigma 11 < 110 > {332}) in alpha iron were performed to investigate the dynamics of defect-loaded GBs under shear deformation. The results show that the loaded self-interstitial atoms (SIAs) reduce the critical stress of the coupled GB motion in the Sigma 3 GB, but increase the critical stress in the Sigma 11 GB. The loaded SIAs in the Sigma 3 GB easily form < 111 > clusters and remain in the bulk when the GB moves away. However, the SIAs move along with the Sigma 11 GB and combine with the vacancies in the bulk, leading to the defect self-healing. The helium (He) atoms loaded into the GBs significantly affect the coupled GB motion. Once He clusters emit interstitials, the Sigma 11 GB carries those interstitials away but the Sigma 3 does not. The loaded He atoms reduce the critical stress of the Sigma 3 GB, but increase the critical stress of the Sigma 11 GB.