Microstructure development in a thermomechanically processed Ti-15V-3Cr-3Sn-3Al alloy

Using a Ti-15V-3Cr-3Sn-3Al alloy, the process of (α + β) microstructure development was studied in heavily cold rolled (by 80%) and aged specimens and in specimens which were rolled, recovered and aged. By aging after 80% cold rolling, α phase precipitates on dislocations introduced by deformation at all aging temperatures were examined (773-973 K). The rearrangement of dislocations in β matrix proceeds, resulting in the formation of subgrains as aging is prolonged. In this case, the variants of a phase are restricted to a few numbers. On the other hand, in the case of the specimen aged at 933 K after 80% cold rolling and annealing at 1073 K for 30 s, α phase precipitates at the subgrain boundary in the recovered β region. More variants in the Burgers relationship are observed than in the rolled aged specimens. In aging at 773 K after the recovery treatment, α precipitates form within β subgrains as well as the subgrain boundaries.