Substructure of recovered Ti-23Nb-0.7Ta-2Zr-O alloy
(School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China )
Abstract: Ti-23Nb-0.7Ta-2Zr-O (TNTZO, molar fraction, %) alloy is a newly developed multifunctional β-type titanium alloy. This alloy was reported to deform via a unique dislocation-free deformation mechanism, and thus its recovery and recrystallization behavior should be further studied and compared with traditional BCC metals. The substructures of the cold-swaged and the annealed TNTZO alloy were investigated by transmission electron microscopy(TEM) to study the recovery of the cold-swaged TNTZO alloy. The results show that no dislocation can be distinguished from the cold-swaged TNTZO alloy due to the heavily-accumulated strains, whereas high density dislocations were observed in the cold-swaged TNTZO alloy after annealing at 800 ℃ for 5 min. During annealing, recovery proceeds through the redistribution and annihilation of the dislocations, which are considered to result from the plastic deformation and the recovery process of the cold-swaged TNTZO alloy is similar to that of ordinary BCC metals.
Key words: β titanium alloy; substructure; recovery; dislocation