Influence of solution treatment on microstructure of a near-α titanium alloy

The effect of solution temperature and cooling rate on the microstructure of Ti-Al-Sn-Zr-Mo-Si-Nb-Ta alloy was investigated by optical microscope (OM) and scanning electron microscope (SEM). The α+ β/β phase transformation temperature of the alloy was identified as 1030-1035 °C, around which the original β grains grew fast. The grain boundary α phase trended to spheroidize and the content of primary αp phase decreased with the increasing solution temperature when the alloy was treated in α+ β field. Meanwhile, the " forked " morphology was found at the edge of intragranular primary αp lath, and it became larger with the increasing solution temperature or decreasing cooling rate. However when the alloy was treated in β field, the α lamella became wider and more orderly arranged, and it ultimately showed widmanstaten structure from acicular martensite via a mixed-structure with weave and widmanstaten structures.