EFFECTS OF MICROSTRUCTURE, SIMULATED BODY AND LIVING BODY ENVIRONMENTS ON FRACTURE CHARACTERISTICS OF IMPLANT MATERIAL TI-5AL-2.5FE

Mechanical properties, fracture toughness and fatigue strength of impl ant material Ti-5Al-2.5Fe were investigated related to the microstruct ure. Effect of the simulated body environment on the fatigue strength and effect of the living rabbit body environment on mechanical propert ies 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 SU S316L. The equiaxed alpha structure which is formed by solution treatm ent at a temperature under beta transus followed by air cooling and ag ing gives the best balance of mechanical properties in Ti-5Al-2.5Fe. T i-5Al-2.5Fe exhibits much greater rotating bending fatigue strength co mpared with SUS316L and equivalent rotating bending fatigue strength t o that of Ti-6Al-4V ELI in the both air and simulated body environment s. Fatigue strength of Ti-5Al-2.5Fe in the simulated body environment is degraded by lowering oxygen content because the formability of oxid e on the specimen surface is considered to be lowered comparing with i n 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 en vironment.