Effects of cold deformation on microstructure and mechanical properties of Ti-35Nb-2Zr-0.3O alloy for biomedical applications

The Ti-35Nb-2Zr-0.3O (mass fraction, %) alloy was melted under a high-purity argon atmosphere in a high vacuum non-consumable arc melting furnace, followed by cold deformation. The effects of cold deformation process on microstructure and mechanical properties were investigated using the OM, XRD, TEM, Vicker hardness tester and universal material testing machine. Results indicated that the alloy showed multiple plastic deformation mechanisms, including stress-induced α” martensite (SIM α”) transformation, dislocation slipping and deformation twins. With the increase of cold deformation reduction, the tensile strength and hardness increased owing to the increase of dislocation density and grain refinement, and the elastic modulus slightly increased owing to the increase of SIM α” phase. The 90% cold deformed alloy exhibited a great potential to become a new candidate for biomedical applications since it possessed low elastic modulus (56.2 GPa), high tensile strength (1260 MPa) and high strength-to-modulus ratio (22.4×10−3), which are superior than those of Ti-6Al-4V alloy.