生体用Ti-5Al-2.5Fe合金の疲労き裂進展特性に及ぼすミクロ組織および擬似生体内環境の影響

抄録

Fatigue crack propagation behaviors of Ti-5Al-2.5Fe with various microstructure for biomedical use were investigated in air and a simulated body environment, Ringer's solution, in comparison with those of Ti-6Al-4V ELI and SUS 316L stainless steel.
The crack propagation rate, da/dN, of equiaxed α structure is nearly the same as that of Widmanstatten α structure in Ti-5Al-2.5Fe in air when da/dN is related to the nominal cyclic stress intensity factor range, ΔK. Ti-5Al-2.5Fe shows nearly same da/dN as Ti-6Al-4V ELI having equiaxed α structure, but shows a greater one than Widmanstatten α Ti-6Al-4V ELI. Without fine precipitated α, the da/dN of Ti-5Al-2.5Fe tested in air and in Paris regime is nearly equal to, but in threshold regime, greater than that of SUS 316L stainlsess steel. Fine precipitated α of Ti-5Al-2.5Fe tested in air makes the da/dN in threshold regime nearly equal to, but in Paris regime greater than that of SUS 316L.
When da/dN is related to ΔK, testing in Ringer's solution makes greater the da/dN of both Ti-5Al-2.5Fe and Ti-6Al-4V ELI than that obtained by testing in air. However, when da/dN is related to the effective cyclic stress intensity factor range, ΔK_eff, the da/dN of both alloys is nearly the same in air and in Ringer's solution.