Grain boundary dislocation structure and motion in an aluminum Σ = 3 [01̄1] bicrystal

High-resolution transmission electron microscopy (HRTEM) observations are presented of a/3[111] grain-boundary dislocations in an aluminum Σ = 3[01̄1] bicrystal. These dislocations are present on both (111) (coherent twin) and (21̄1̄) (incoherent twin) facets of the bicrystal boundary. The dislocations on the coherent twin facet migrate by a climb process that increases the thickness of the twinned material. These dislocations originate on a Σ = 3 (21̄1̄) incoherent twin boundary where they are closely spaced and dissociated in a wide core configuration. Atomistic calculations of the defect structure and interaction of multiple a/3[111] grain boundary dislocations are discussed.