Quantifying the effect of twin boundaries on grain boundary activities in nanotwinned copper: A molecular dynamics simulation

Twin boundaries (TBs) play an important role in work hardening of nanotwinned metals. However, the effect of TBs on grain boundaries (GBs) activities in nanotwinned metals has not given detailed analysis due to the limited spatial and temporal resolution of experimental technique and the unrealistic model with flat GBs in simulation. Therefore, the nanotwinned copper with more natural GBs was created in this study by using phase field model for molecular dynamics (MD) simulation. In addition, a novel code was developed to quantitatively analyze the GB activities including deformation and rotation in the initial deformation stage. The results show that the average flow stress in nanotwinned copper is larger than that in the twin-free model and the stress increases with decreasing twin spacing. From the statistical results of GB activities, we can find that the rotation of GBs seems to be not affected by the TBs, but the deformation of GBs will be detained by TBs which finally results in improving stress concentration on GBs. Hence, with decreasing twin spacing, the deformation mechanism shifts from partials gliding on different slip systems to partials gliding on the adjacent plane of TBs due to the stress concentration.