High-resolution transmission electron microscopic observations were made of the motion of grain-boundary dislocations within a  = 3 [0¯11] bi-crystal. The results revealed the glide of dissociated a/3[111] grain-boundary dislocations on the incoherent  = 3 (2¯1¯1) boundary. These dislocations were subsequently incorporated into growing coherent twin lamella where further motion occurred via climb. An analysis of the tip of the advancing twin suggested that the nucleation of coherent twin segments could be initiated by the absorption of a lattice dislocation in the boundary; with subsequent dissociation to form a/3[111] and a/6[¯211] grain-boundary dislocations.

D.L.Medlin, C.B.Carter, J.E.Angelo, M.J.Mills: Philosophical Magazine A, 1997, 75[3], 733-47