K. Uchida, N. Shigenaka, Hitachi-GE Nuclear Energy, Ltd., Hitachi, Japan; T. Sakuma, Oita University, Oita, Japan; K. Yamauchi, Tohoku University, Sendai, Japan
Ti-Ni shape memory alloys(SMAs) show excellent mechanical properties and corrosion resistance, and therefore, have been already used in industrial, medical, and other applications. In most SMAs in practical use, the alloys deformed in the martensite phase are utilized for SMA devices because the shape recovery strain and stress are obtained by heating over austenite finish temperature. The martensitic transformation temperatures of Ti-Ni SMAs depend on chemical composition, working processes and heat treatment. The addition of third elements to Ti-Ni alloys changes their transformation temperatures and shape memory properties. The large transformation hysteresis of the Ti-Ni-Nb alloys is suitable for the pipe joints, Ti-Ni-Nb alloys have been already used practically. In this study, in order to apply the Ti-Ni-Nb alloys for SMA pipe joints, the transformation temperatures, mechanical properties of the alloy were investigated.
