Large-scale atomistic simulations were used to investigate the properties of screw dislocation dipoles. Spontaneous annihilation was observed for dipole heights which were less than 1nm. Equilibrated dipoles with heights that were greater than 1nm adopted a skew configuration, due to the elastic anisotropy of Cu. The equilibrium splitting-width of the screw dislocations decreased with decreasing dipole height; as expected from elasticity theory. The energy barriers, and the corresponding transition states for the annihilation of stable dipoles, were determined for straight and flexible dislocations having dipole heights of up to 5.2nm. In both cases, annihilation was initiated by the cross-slip of one of the dislocations. In the case of straight dislocations, the activation energy exhibited a linear dependence upon the inverse dipole height. In the case of flexible dislocations, the dependence was essentially linear for the present dipoles.

Simulation of Structure and Annihilation of Screw Dislocation Dipoles. T.Rasmussen, T.Vegge, T.Leffers, O.B.Pedersen, K.W.Jacobsen: Philosophical Magazine A, 2000, 80[5], 1273-90