Precipitation behavior of α phase during aging treatment in a β-quenched Ti-7333

In this work, the precipitation behavior of alpha phase during the isothermal aging treatment was investigated in the beta-quenched Ti-7333. The results indicate that dislocations contribute to the precipitation of alpha phase with a dot-like morphology at the beginning of aging treatment, and these dot-like alpha precipitates holding the same Burgers orientation relationship (BOR) with respect to the beta matrix coalesce into the platelet morphology. The platelet like alpha precipitates that orientate to different growth directions combine with each other to form the V-shaped configuration. And the formation of this configuration is closely related with the variant selection (VS) of alpha phase, which is resulted from the perfect accommodation of transformation strain within the beta matrix. Meanwhile, it is found that low-angle grain boundaries (LAGBs) and high-angle grain boundaries (HAGBs) can be decorated by alpha phase during the aging treatment, and its precipitation degree significantly depends on the angle between the closely packed direction of alpha GB and the GB plane. The volume fraction of alpha phase increases with increasing aging time, and this increasing volume fraction eventually results in the increase in micro-hardness of the alloy.