Abstract
Ti-29Nb-l3Ta-4.6Zr alloy (TNTZ) is expected to be used as biomedical applications such as a spinal fixation device. For a practical application, high durability of the spinal fixation device is required in order to ensure mechanical safety. The durability of the spinal fixation device with a rod made of TNTZ subjected to a surface hardening treatment was investigated in this study. The rod was prepared through a levitation melting, a hot-forging at 1273K, a solution treatment at 1063K for 3.6 ks subsequently water quenching, machining and finally a cavitation peening (CP) treatment for surface hardening (TNTZ-CP rod). Microstructure was observed using transmission electron microscopy (TEM). The durability was evaluated by compressive fatigue test applied to the spinal fixation device. Nano-scale graines were observed at the surface of the TNTZ-CP rod. The nanocrystalization was caused by the CP treatment. The compressive fatigue strength of the spinal fixation device with the TNTZ-CP rod was higher than that of spinal fixation device with a non-CP treated TNTZ rod.
