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. (C) 2001 Elsevier Science B.V. All rights reserved.