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

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