Effects of a disconnection dipole on the shear-coupled grain boundary migration

Abstract Effects of a preexisting disconnection dipole on the migration of a Σ 5 ( 3 ¯ 1 0 ) / [ 0 0 1 ] grain boundary (GB) at low shear rates have been investigated by using the minimized bulk dissipation phase field crystal model. Simulation results show that the two disconnections play different roles during the process of shear-coupled GB migration via different behaviors regarding heterogeneous nucleation and propagation of disconnections. Specifically, the different roles can be attributed to their structural deviation from the equilibrated crystallographic structure caused by shear loading: one disconnection contributes to the onset of GB migration by heterogeneous nucleation of disconnections, while the other one slows down the corresponding GB migration dynamics through the impediment of homogeneous nucleation in the flat GB plane.