High-temperature shape memory alloys, especially titanium-nickel-based alloys, are used in industrial and medical applications because of their unique combination of perfect shape memory and ductility. However, their use is restricted to temperatures around 373 K, the temperature of the thermoelastic martensitic transformation. There is now a need for shape memory engineering alloys with higher temperatures for use as actuators in motor vehicles, aircraft engine and pipe couplings, and titanium-palladium alloys with a martensite start temperature of 823 K may be suitable.

Now, researchers from Japan have studied the means to improve the characteristics of these alloys (D. Golberg, Y. Xu, Y. Murakami, K. Otsuka, T. Ueki and H. Horikawa,Mater. Lett., 1995, 22, (5, 6), 241–248). Using Ti₅₀Pd_50-xNix (x = 10, 15, 20) alloy high temperature tensile tests at 293–858 K were carried out. They found that reversibly transforrning the as-rolled martensitic phase and annealing it below the recrys-tallisation temperature improved the shape memory characteristics of this system.