Development of biomedical Ti-Cr alloys with changeable young's modulus via deformation-induced transformation

Nowadays, biomaterials that are used to design spinal fixtures cannot meet the requirements of both surgeons and patients; surgeons require the material to have a high Young's modulus to suppress springback during the operation, whereas patients require the material to have a low Young's modulus to prevent the stress-shielding effect. Therefore, new titanium alloys with good biocompatibility and a changeable Young's modulus require to be developed. The ω phase significantly influences the mechanical properties of titanium alloys. According to reports, the ω phase can be introduced by deformation at room temperature in β-type Ti-Cr alloys. The effects of deformation-induced phases on the mechanical properties of a metastable β-type Ti-12Cr alloy were investigated. The experimental results indicate that the Young's modulus, tensile strength, and Vickers hardness of the Ti-12Cr alloy increase remarkably by cold rolling. The transmission electron microscopy (TEM) observation of a Ti-12Cr alloy shows that deformation-induced ω phase transformation occurs in the Ti-12Cr alloy during cold rolling. Therefore, the increase in the Young's modulus of the alloy after cold rolling is ascribable to the deformation-induced ω phase, which is formed in the alloy during cold rolling at room temperature.