Experimental evidence of precipitation of all 12 variants in a single β grain in titanium alloys

The effect of the changing of the local composition of the β matrix on the precipitation of the phase has been investigated by electron backscatter diffraction (EBSD) to obtain more insight in the nucleation and variant selection of these plates based on the Ti-5.04Al/Ti-1.52Mo (at.%) diffusion couple. The results showed that the composition gradient was formed from one side of the diffusion couple to another side after diffusion annealing. Followed by a secondary heat treatment process, it was found for the first time that all 12 variants formed in a single β grain in the diffusion zone in the Ti-5.04Al/Ti-1.52Mo diffusion couple, which indicated that the changing of the local composition of the β matrix significantly weakened the variants selection behavior.