Yoko Yamabe‐Mitarai

To develop high-temperature shape memory alloys, Ti–50(Pt,Ir)mol% compounds are noted because of their martensitic transformation from B2 to B19(2H) or 4H(4O) structures above 1273 K. A thermal expansion measurement and loading-unloading compression test were performed for Ti–50(Pt,Ir) to determine if the shape memory effect or superelasticity was shown. The thermal expansion measurement indicated the shape recovery in some of the compounds. The maximum shape recovery was about 4% by reheating a

Rising martensitic transformation temperature is required to develop HTSMAs. Then, we have focused on the alloys consisting of Ti and precious metals such as TiPt, TiPd and TiAu due to their high martensitic transformation temperatures. To strengthen these compounds and control phase transformation temperature, third elements were partially substituted to the alloys. Some of the TiPd–base compounds indicated 100% shape recovery at temperature range between 400-450 °C. The effect of third element

In this paper high-temperature shape memory alloys based on TiPd and TiPt are reviewed. The effect of the alloying elements in ternary TiPd and TiPt alloys on phase transformation and strain recovery is also discussed. Generally, the addition of alloying elements decreases the martensitic transformation temperature and improves the strength of the martensite and austenite phases. Additionally, it also decreases irrecoverable strain, but without perfect recovery due to plastic deformation. With t

The temperature dependence of the strength of Ir3Nb with the L12 structure has been investigated using compression tests between -196 and 1200 degrees C. Below room temperature, the strength decreased with increasing temperature. An anomalous temperature dependence of the strength was observed between room temperature and 800 degrees C; the strength increased with increasing temperature. Above 800 degrees C, the strength again decreased with increasing temperature. The Burgers vectors of the dis