Previous simulation studies, in which a screw dislocation in face-centered cubic Ni was found to spontaneously attain a low energy partially cross-slipped configuration upon intersecting a forest dislocation, were extended. Using atomistic (molecular statics) simulations with embedded atom potentials, the activation barrier was evaluated for a dislocation to transform from fully residing on the glide plane to fully residing on a cross-slip plane intersecting a forest dislocation in both Ni and Cu. The activation energies were obtained by determining equilibrium configurations (energies) when variable pure tensile or compressive stresses were applied along the [111] direction on the partially cross-slipped state. It was shown that the activation energy was a factor of 2–5 lower than that for cross-slip in isolation via the Escaig process. The cross-slip activation energies obtained at the intersection in Cu were in reasonable accord with the experimentally determined cross-slip activation energy for Cu. Further, the activation barrier for cross-slip at these intersections was shown to be linearly proportional to (d/b)[ln(√3d/b)]1/2, as in the Escaig process, where d was the Shockley partial dislocation spacing and b was the Burgers vector of the screw dislocation. These results suggest that cross-slip should be preferentially observed at selected screw dislocation intersections in face-centered cubic materials.

Activated States for Cross-Slip at Screw Dislocation Intersections in Face-Centered Cubic Nickel and Copper via Atomistic Simulation. S.I.Rao, D.M.Dimiduk, J.A.El-Awady, T.A.Parthasarathy, M.D.Uchic, C.Woodward: Acta Materialia, 2010, 58[17], 5547-57