Young's Modulus Change Due to Deformation-Induced Phase Transformation In Beta-Type Titanium Alloys for Biomedical Applications

Titanium and its alloys are widely utilized for biomedical applications because of their high specific strength, corrosion resistance, and biocompatibility. In the past two decades, many researchers gave an effort to achieve a low Young’s modulus for such the titanium alloys. However, Young’s modulus of the metallic spinal rod should be not only low to prevent stress shielding effect for the patient but also high to suppress springback for the surgeon. Therefore, a novel function of biomedical titanium alloys, which is the self-adjustment of Young’s modulus, is proposed in this study. Deformation-induced omega phase transformation was introduced into beta-type titanium alloys so that the Young’s modulus of only the deformed part would increase by deformation during operation, while that of the non-deformed part would remain low. The Young’s modulus increase due to deformation was investigated for a several beta-type titanium alloys. These types of titanium alloys successfully underwent deformation-induced omega phase transformation and exhibited the increase in the Young’s modulus by deformation.