Abstract: Primary α phase microstructure of Ti62A titanium alloy solution treated at 910 ℃ for different time was characterized by means of OM, SEM and EBSD techniques, to investigate the evolution characteristics of the primary α phase and the spheroidization mechanism during the solid solution process. The results show that the initial microstructure of the forged Ti62A titanium alloy consists of the primary α phase, lamellar α phase and residual β phase. During the solid solution process at 910 ℃, the lamellar α phase dissolves rapidly, and the volume fraction of primary α phase first decreases and then remains unchanged with the increase of solution time, but the axis/diameter ratio is basically maintained at about 2.1. During the solution treatment, a large misorientation appeares inside the grains of the primary α phase, producing α/α grain boundaries with different orientations. With the growth of solution time, the grain is prone to grain boundary separation and the formation of new equiaxed primary α phase when the misorientation of α/α grain boundaries within the long strip primary α phase is greater than 10°.

Key words: Ti62A titanium alloy, solution treatment, microstructure, α phase, spheroidization mechanism