Optimization of Cr content of metastable ¦Â-type Ti-Cr alloys with changeable Young¡¯s modulus for spinal fixation applications

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• 作者：Xingfeng Zhao^a ; Mitsuo Niinomi^b ; ^{niinomi@imr.tohoku.ac.jp} ; Masaaki Nakai^b ; Junko Hieda^b ; Takuya Ishimoto^c ; Takayoshi Nakano^c
• 关键词：Biomaterials ; ¦Â-type Ti&ndash ; Cr alloys ; Changeable Young&rsquo ; s modulus ; Deformation-induced ¦Ø phase ; Cytocompatibility
• 刊名：Acta Biomaterialia
• 出版年：2012
• 出版时间：July, 2012
• 年：2012
• 卷：8
• 期：6
• 页码：2392-2400
• 全文大小：1606 K

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.