The transformations of dipoles of dissociated edge dislocations in aluminium were investigated using molecular dynamics for dipole heights ranging from one to ten {111} interplanar distances and at up to 900K. Three types of configurations, hollow, vertical compact and inclined dipoles, were considered and their relative stabilities compared. Hollows were unstable at finite temperature. Dipoles neither annihilate nor form stable hollow cores but transform into height- and temperature-dependent layouts including cores containing ordered free volumes, zig-zag faulted dipoles and agglomerated truncated stacking fault tetrahedra. Small individual stacking fault tetrahedra were formed at the highest temperatures, attesting to short-range pipe diffusion. These rearranged configurations were strong obstacles to mobile dislocations, thence potential nucleation sites for dislocation entanglement and self-patterning under single slip. A new thermally activated mechanism of stacking-fault tetrahedra formation directly from vacancy clusters resulting from local dipole pinching-off was reported.

The Transformation of Edge Dislocation Dipoles in Aluminium. H.Wang, D.Xu, R.Yang, P.Veyssière: Acta Materialia, 2008, 56[17], 4608-20