Dislocation structure of non-habit plane of α precipitates in a Ti–7.26 wt.% Cr alloy

The dislocation structures of edge facet and end face of proeutectoid α precipitates in a β matrix in a Ti–7.26 wt.% Cr alloy were studied using transmission electron microscopy. Two sets of dislocations, which are parallel to the dislocations on the habit plane of the α plate, were observed on the edge facet. The spacing of one set of coarse-spaced dislocations is about 9.4 nm. Their Burgers vector is [1 0 0]β([2 −1 −1 0]α/3) determined by g · b contrast analyses. The spacing of the other set of fine-spaced dislocations is about 1.8 nm. Their Burgers vector possibly is [1 1 1]β/2([1 1 −2 0]α/3). A dislocation network on the end face is formed by the dislocations on the habit plane and edge facet looping around the α plate. Another set of dislocations was observed on the end face at intersections between the dislocations on the habit plane and the coarse-spaced dislocations on the edge facet. Their Burgers vector possibly is [1 1 −1]β/2([2 −1 −1 −3]α/6). Based on the observations, a three-dimensional model of the dislocation structure of the α plate was constructed.