Thermal cycling stability and two-way shape memory effect of Ni–Cu–Ti–Hf alloys

Thermal cycling stability and shape memory effect (SME) of quarternary Ni–Cu–Ti–Hf alloys (Ni45Cu3Ti37Hf15, Ni43Cu7Ti35Hf15 and Ni40Cu10Ti40Hf10) have been studied. The Ni45Cu3Ti37Hf15 and Ni43Cu7Ti35Hf15 alloys are high-temperature shape memory alloys with good thermal stability. Although the thermal cycling stability of Ni40Cu10Ti40Hf10 is better than the other two alloys, its phase transformation temperatures are below 373 K. All the three alloys can express two-way SME. A novel two-way SME has been observed in Ni40Cu10Ti40Hf10 alloy.