Dislocation motion in BCC metals by molecular dynamics

We performed molecular dynamics (MD) simulation of edge dislocations in BCC metal Mo with 1/2〈1 1 1〉 Burgers vector gliding on (1 1 0) plane using the Finnis–Sinclair N-body empirical potential and periodic boundary conditions (PBC). The profile of dislocation line, extracted from atomic displacements during MD simulation, suggests a dominant mechanism of double-kink nucleation, without appreciable kink migration. This observation is consistent with further simulations in which dislocations with pre-existing kinks are observed to move at the same velocity as the initially straight dislocations. Our results show a linear stress dependence of the dislocation velocity and a decrease of mobility with increasing temperature, both features interpreted as signifying that the simulations pertain to the viscous phonon drag regime of dislocation mobility.