文摘
Metallic implant rods used in spinal fixtures should have a Young¡¯s modulus that is sufficiently low to prevent stress shielding for the patient and sufficiently high to suppress springback for the surgeon. Therefore, we propose a new concept: novel biomedical titanium alloys with a changeable Young¡¯s modulus via deformation-induced ¦Ø phase transformation. In this study, the Cr content in the range of 10-14 mass % was optimized to produce deformation-induced ¦Ø phase transformation, resulting in a large increase in the Young¡¯s modulus of binary Ti-Cr alloys. The springback and cytotoxicity of the optimized alloys were also examined. Ti-(10-12)Cr alloys exhibit an increase in Young¡¯s modulus owing to deformation-induced ¦Ø phase transformation. In this case, such deformation-induced ¦Ø phase transformation occurs along with {3 3 2}¦Â mechanical twinning, resulting in the maintenance of acceptable ductility with relatively high strength. Among the examined alloys, the lowest Young¡¯s modulus and largest increase in Young¡¯s modulus are obtained from the Ti-12Cr alloy. This alloy exhibits smaller springback than and comparable cytocompatibility to the biomedical Ti alloy Ti-29Nb-13Ta-4.6Zr.