The activation energy of cross-slip in L12 ordered alloys

In ordered intermetallics with L12 structure cross-slip from the primary {111} glide plane onto a {010} cube plane leading to locked configurations is thought to be responsible for the peak in the temperature dependence of the flow stress. Earlier calculations of the cross slip activation energy in the framework of linear elastic continuum theory suffer from an ill-defined core cut-off parameter and an unknown recombination distance of Shockley partials. We determine the core energy from the Peierls model and calculate interaction energies of dislocation segments in the framework of linear anisotropic elasticity. Of two possible processes with cross slip distance b/2 or b, the latter is energetically favored. Activation energies and activation areas are presented as a function of applied stress in the cross slip plane, giving ΔG=1–2 eV and a=5–10 b2 as typical values for Ni3Al. The results are consistent with recent atomistic calculations by other authors.