Climb and glide ofa/3〈111〉 dislocations in an aluminium Σ = 3 boundary

High-resolution transmission electron microscopy observations are presented of the motion of grain-boundary dislocations within an aluminium Σ = 3[011] bicrystal. The observations show the glide of dissociated a/3[111] grain-boundary dislocations on the incoherent Σ = 3(211) boundary. These dislocations are subsequently incorporated into a growing coherent two lamella where further motion occurs by climb. Analysis of the tip of the advancing twin suggests that nucleation of coherent twin segments may be initiated by the absorption of a lattice dislocation in the boundary with the subsequent dissociation to form a/3[111] and a/6[211] grain-boundary dislocations.