High-resolution transmission electron microscopic observations and atomistic simulations were made of {1¯11}/{121} facets in a 90º tilt boundary. These revealed the presence of an approximately 1nm-wide layer, with stacking-faults which were distributed at the density of 1 per 3 close-packed planes. This interfacial reconstruction, which formed the rhombohedral 9R stacking arrangement, was similar to that found previously for near-Σ3 {112} boundaries in low stacking-fault energy metals. A general approach was described for partitioning the grain boundary orientation into a set of Shockley partial dislocations, and then applying this description to the {1¯11}/{121} interface. The results of such an analysis explained the fault distribution, and the geometry of the local plane bending. They also showed that the 9R stacking occurred in both the Σ3 {112} and {1¯11}/{121} interfaces, due to the similar ratios of 30º and 90º Shockley dislocations in both cases. This method of description had limitations with regard to, for instance, ⅛[101] relaxation.

A Dislocation-Based Description of Grain Boundary Dissociation - Application to a 90° (110) Tilt Boundary in Gold. D.L.Medlin, S.M.Foiles, D.Cohen: Acta Materialia, 2001, 49[18], 3689-97