The influence of prior cold deformation on precipitation of alpha phase and variation of hardness in Ti-10Mo-8V-1Fe-3.5Al during aging treatment

The influence of prior cold deformation on precipitating of alpha phase as well as the variation of hardness during aging has been investigated in solution-treated Ti-10Mo-8V-1Fe-3.5Al alloys. The results show that alpha phase precipitation could be obviously accelerated by the prior cold deformation. In the predeformed samples, a network pattern structure was observed with an optical microscope after aging treatment. It could be attributed to the phenomenon that the plate-shape alpha precipitates prefer to nucleate and grow in the regions with a high density of dislocations, especially inside slip bands. The hardness of both the predeformed and undeformed TB3 specimens after different aging times was measured and further predicted by a proposed strengthening model based on the grain refinement mechanism of the beta phase. The predicted results are consistent with the experimental results, especially in the later aging stages.