title: Deformation-induced changeable Young's modulus with high strength in β-type Ti-Cr-O alloys for spinal fixture.
abstract: In order to meet the requirements of the patients and surgeons simultaneously for spinal fixation applications, a novel biomedical alloy with a changeable Young's modulus, that is, with a low Young's modulus to prevent the stress-shielding effect for patients and a high Young's modulus to suppress springback for surgeons, was developed. In this study, the chromium and oxygen contents in ternary Ti(11, 12 mass%)Cr-(0.2, 0.4, 0.6 mass%)O alloys were optimized in order to achieve a changeable Young's modulus via deformation-induced ω-phase transformation with good mechanical properties. The Young's moduli of all the examined alloys increase after cold rolling, which is attributed to the deformation-induced ω-phase transformation. This transformation is suppressed by oxygen but enhanced with lower chromium content, which is related to the β(bcc)-lattice stability. Among the examined alloys, the Ti-11Cr-0.2O alloy shows a low Young's modulus of less than 80GPa in the solution-treated (ST) condition and a high Young's modulus of more than 90GPa in the cold rolled (CR) condition. The Ti-11Cr-0.2O alloy also exhibits a high tensile strength, above 1000MPa, with an acceptable elongation of ~12% in the ST condition. Furthermore, the Ti-11Cr-0.2O alloy exhibits minimal springback. This value of springback is the closest to that of Ti64 ELI alloy among the compared alloys. Therefore, the Ti-11Cr-0.2O alloy, which has a good balance between large changeable Young's modulus, high tensile strength, good plasticity, and minimal springback, is considered to be a potential candidate for spinal fixation applications.
authors: Graduate Student, Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan.
authors: Huihong
authors: H
authors: Liu
authors: Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
authors: Mitsuo
authors: M
authors: Niinomi
authors: Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
authors: Masaaki
authors: M
authors: Nakai
authors: Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
authors: Junko
authors: J
authors: Hieda
authors: Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
authors: Ken
authors: K
authors: Cho
mesh_terms: D000497:Alloys / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry; D002857:Chromium / Q000737:chemistry*; D055119:Elastic Modulus; D008422:Materials Testing; D009984:Orthopedic Fixation Devices; D010100:Oxygen / Q000737:chemistry*; D013131:Spine / Q000601:surgery*; D013718:Tensile Strength; D014025:Titanium / Q000737:chemistry*
chemical_list: D000497:Alloys; D001672:Biocompatible Materials; D002857:Chromium; D014025:Titanium; D010100:Oxygen
keywords: Athermal ω phase; Changeable Young's modulus; Deformation-induced ω-phase transformation; Springback; Ternary Ti–Cr–O alloys