It was noted that the interaction of dislocations with grain boundary junctions played an important role during plastic deformation and stress relaxation in polycrystalline thin films. In the present work, arrays of secondary grain boundary dislocations and their behavior at junctions between orthogonal Σ = 3 {111} and Σ = 3 {112} grain boundaries in Au thin films were studied by means of room temperature and in situ transmission electron microscopy. Via diffraction contrast experiments, it was found that these dislocations had Burgers vectors of the type, a/6<112>. In situ transmission electron microscopic experiments, conducted at elevated temperatures, showed that the arrays of secondary grain boundary dislocations on {111} twin planes originated in the {112} boundaries where they accommodated a small rotational misorientation from the exact coincident-site lattice orientation. It was proposed that the discontinuous distribution of secondary grain boundary dislocations in the {112} boundary produced a climb stress that drove dislocation motion. As the dislocations in the grain boundary increased their separation, the climb stress and the misorientation between grains decreased. In order to test this explanation, the balance between the reduction in energy due to motion in response to the climb stress, and the increase in energy due to lengthening of the dislocation line on the {111} twin plane, was considered.

Dislocation Emission at Junctions between Σ = 3 Grain Boundaries in Gold Thin Films. G.Lucadamo, D.L.Medlin: Acta Materialia, 2002, 50[11], 3045-55