A strong and ductile pure titanium

The low strength of pure Ti significantly limits its biomedical applications, although its biocompatibility is the best. Here, by controlled annealing and cryogenic drawing after rolling, we synthesize a set of pure Ti combining the strength of ultrafine-grained Ti and the ductility of coarse-grained Ti. The microstructure is characterized with fine grains (a few microns), abundant twins, and high dislocation density, which enable both short dislocation-slip path for strengthening and enough defects accumulation room for work hardening. Twins provide strengthening due to the subdivision effect of twin lamella on grains and dislocations accumulation near the twin boundaries. High flow stress helps to activate FCC phase transformation at large-strain stage. The excellent ductility is originated from the sustained work hardening enabled by the initial texture, fine grains, the interaction among dislocations, FCC lamellae, and twins.