抄録
Mechanical properties, fracture toughness and fatigue strength of implant material Ti-5Al-2.5Fe were investigated related to the microstructure. Effect of the simulated body environment on the fatigue strength and effect of the living rabbit body environment on mechanical properties and fracture toughness in Ti-5Al-2.5Fe were then investigated. The data of Ti-5Al-2.5Fe were compared with those of Ti-6Al-4V ELI and SUS316L.
The equiaxed α structure which is formed by solution treatment at a temperature under β transus followed by air cooling and aging gives the best balance of mechanical properties in Ti-5Al-2.5Fe. Ti-5Al-2.5Fe exhibits much greater rotating bending fatigue strength compared with SUS316L and equivalent rotating bending fatigue strength to that of Ti-6Al-4V ELI in the both air and simulated body environments. Fatigue strength of Ti-5Al-2.5Fe in the simulated body environment is degraded by lowering oxygen content because the formability of oxide on the specimen surface is considered to be lowered comparing with in air. The mechanical properties of Ti-5Al-2.5Fe is not changed in the living rabbit body environment. The hard surface corrosion layer is, however, formed on the surface of SUS316L in the living rabbit body environment.
