A dislocation-based description of grain boundary dissociation:: Application to a 90° ⟨110⟩ tilt boundary in gold

High resolution transmission electron microscopy (HRTEM) observations and atomistic simulations of {1 (1) over bar1}/{121} facets in a gold 90 degrees tilt boundary show the presence of a similar to 10 Angstrom wide layer with stacking faults distributed one to every three close-packed planes. This interfacial reconstruction, which forms the rhombohedral 9R stacking arrangement, is similar to that found previously for near-Sigma = 3{112} boundaries in low stacking fault energy metals. We discuss a general approach for partitioning grain boundary orientation into a set of Shockley partial dislocations and then apply this description to the {11}/{121} interface. The analysis explains both the distribution of faults and the geometry of the local plane bending and shows, further, that the 9R stacking occurs in both the Sigma = 3{112} and {1 (1) over bar1}/{121} interfaces due to the similar ratios of 30 degrees and 90 degrees Shockleys in both cases. Finally, we discuss limitations of this description, in particular concerning a 1/8[(1) over bar 01] relaxation that is predicted by the atomistic simulations. published by Elsevier Science Ltd on behalf of Acto Materialia Inc.