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

Profound and comprehensive investigations on the morphology characteristics of alpha precipitates are essential for the microstructural control of metastable beta titanium alloys. At the very beginning of aging treatment, intragranular alpha precipitates with a dot-like morphology begin to generate nearby the dislocations, then those dot-like alpha 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 alpha precipitates gradually combine with each other to form the V-shaped clusters or the triangular ones. The dislocations of {1 (1) over bar0}(alpha) < 11 (1) over bar >(beta) edge type are evidenced within the beta grains, and it is found that variant selection of alpha precipitates induced by the transformation strain and the interplay between alpha 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 alpha precipitates related to the crystal defects and the strain accommodation of alpha variants in metastable beta titanium alloys. (C) 2021 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.