Near-coincidence-sites modeling of the edge facet dislocation structures of α precipitates in a Ti–7.26 wt.% Cr alloy

While much attention has been paid to the orientations and structures of the habit planes of various precipitates, the orientations and structures of the edge facets are less well understood. This work presents a new approach to the interpretation of edge facets. The orientations and dislocation structures of the edge facets of α precipitates in a β matrix in a Ti-7.26 wt.% Cr alloy were investigated with a near-coincidence-sites (NCS) model combined with the analysis of Moiré planes based on the O-lattice theory. The distribution of NCS clusters exhibits two orders of modulated periodicities, which can be defined by the approximate intersections between several sets of Moiré planes. Two possible edge facets are suggested, based on the NCS distribution. Based on the misfit analysis, the dislocation structures in the edge facets were calculated. The calculated orientations and dislocation structures of the edge facets are consistent with the experimental observations.