Effect of special primary α grain on variant selection of secondary α phase in a near-α titanium alloy

Abstract

Based on the statistical analysis on the orientation relationship (OR) among adjacent primary α (αp) grain, β phase and secondary α (αs) phase in a bimodal-structure near-α titanium alloy, the effect of special αp on the variant selection of αs was investigated. The results showed that only a small part of αp grains held the Burgers OR (BOR) with the neighbouring β phase, and the αs tended to preferentially nucleate on the BOR-αp grain and shared a common orientation with the BOR-αp grain. Meanwhile, the driving force for the variant selection was discussed base on the competition between the αp-β and αp-αs interfacial energies, which indicated that the variant selection resulted from the minimal αp-αs interfacial energy.