Morphology characteristics of α precipitates related to the crystal defects and the strain accommodation of variant selection in a metastable β titanium alloy

Profound and comprehensive investigations on the morphology characteristics of α precipitates are essential for the microstructural control of metastable β titanium alloys. At the very beginning of aging treatment, intragranular α precipitates with a dot-like morphology begin to generate nearby the dislocations, then those dot-like α precipitates with the same crystallographic orientation tend to connect with each other to develop a lath-like morphology. With the progress of aging treatment, the orientated lath-like α precipitates gradually combine with each other to form the V-shaped clusters or the triangular ones. The dislocations of {11¯0}_β <111¯>_β edge type are evidenced within the β grains, and it is found that variant selection of α precipitates induced by the transformation strain and the interplay between α variants and the dislocations are confirmed as the key factors for the formation of the V-shaped or triangular clusters. The results of this work could provide underlying knowledge on the morphology characteristics of intraguranular α precipitates related to the crystal defects and the strain accommodation of α variants in metastable β titanium alloys.