TiNi形状記憶合金焼結体の曲げ疲労特性

抄録

We fabricated a sophisticated functionally graded TiNi shape memory alloy (SMA) via powder metallurgy and plastic working. The material can be utilized as a medical guidewire with varying bending rigidity values from high to low along the wire axis and an actuator. In general, sintered materials are not used under severe bending deformation conditions because of their low deformability; however it is necessary to consider the materials that can withstand such deformation, especially for a medical guidewire, which is made from sintered SMA. In this study, we investigated the bending fatigue properties of a sintered TiNi SMA wire via an alternating-plane bending fatigue test. From the experiment, we found that the fatigue life of this wire is much shorter than that of a wrought TiNi SMA wire because of its low density. We therefore conducted a cold rolling to improve the density of the sintered TiNi SMA and achieved longer fatigue life than that of a sintered TiNi SMA.