An extended near-coincidence-sites method and the interfacial structure of austenite precipitates in a duplex stainless steel

The faceted morphology and dislocation structures in all the facets of austenite precipitates in a duplex stainless steel were investigated with an extended near-coincidence-sites (NCS) method based on the orientation relationship (OR) generated by the O-line model. The prominent facets of the precipitates are parallel to three sets of principal Moire planes containing high areal density of NCS, respectively. The Burgers vector and the spacing of the misfit dislocations were determined by a Moire plane trace analysis and a displacement decomposition method. The observed misfit dislocations were consistently explained by the current approach, but the calculated fine dislocations were not observed experimentally. The terrace-ledge-kink structures in terms of both ferrite and austenite lattices were also graphically illustrated. The present geometric approach can also be applied to other systems containing lath- or rod-shaped precipitates, especially when the interfacial structures cannot be described by periodic O-lattice elements. (c) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.