A biomedical β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ) (mass%), which is composed of non-toxic and allergy-free elements and exhibits low Young's modulus similar to that of cortical bone, has been developed by the authors. According to our previous reports, the mechanical properties including fatigue property of TNTZ can be improved significantly by thermomechanical treatments. On the other hand, fatigue property is one of the most important properties when TNTZ is practically employed as a material of metallic rod for spinal fixation. Therefore, in order to improve the fatigue property of TNTZ, the thermomechanical treatment was optimized for this application in this study.
