Double-fold effect of vacancies and interstitials on the migration of Σ3{112} incoherent twin boundary in copper

The migration of Σ3{112} incoherent twin boundary (ITB) in nanotwinned face-centered cubic metals/alloys can lead to twinning or detwinning, thereby significantly influencing the stability of the nanotwinned structure; however, the effect of radiation-induced defects on the migration of the ITB is not fully understood and needs further investigation. In the present study, the effect of vacancies and interstitials on the migration of the ITB in Cu was systematically studied by molecular dynamic simulation method. The simulation results revealed that vacancies/interstitials have double-fold effect on the migration of the ITB: resistance effect works during absorption process of vacancies/interstitials into the ITB, while the absorbed vacancies/interstitials can accelerate rather than retard the migration of the ITB. Importantly, the resistance effect plays a dominant role, thus the migration of ITB can be retarded by radiation-induced defects. Furthermore, the underlying mechanism of the double-fold effect was discussed that cross-layer rearrangement of vacancies in the ITB is prevailing in retarded effect on the ITB migration. The present work gives a deeper insight into the effect of radiation-induced defects on the migration of ITB.