Molecular dynamics simulation of grain boundary plasticity in magnesium and solid-solution magnesium alloys

The deformation behavior at the grain boundary was investigated by the molecular dynamics simulation using two models based on different kinds of [1−100] symmetric tilt boundaries (Σ25 with a tilt angle of θ = 23° and Σ10 with θ = 78°) in magnesium. Grain boundary migrations occurred in both models due to the reduction in the internal energy during deformation. The deformation mechanism at the grain boundary was shown to be the twinning induced grain boundary migration. The grain boundary migration was affected by the grain boundary structures, and it was enhanced in the grain boundaries with high energies. On the other hand, the grain boundary migration was suppressed by the addition of solute atoms, i.e., aluminum and silver. The silver atoms were found to be more effective for suppression than the aluminum atoms. These behaviors occurred in both the molecular dynamics simulation and the experiments.