Functional Behavior of NiTiHfNb-based High-Temperature Shape Memory Wires

A family of NiTiHfNb-based wires has recently been developed by SAES Group. These wires represent a viable solution for high-temperature shape memory actuators in many different applications within aerospace, and automotive industries.

In the present work the effects of different thermo-mechanical treatments, some of them being carried out within training sequences, on the microstructure of thin (Ф<300μm) NiTiHfNb wires have been investigated by scanning electron microscopy (SEM) and comparatively analyzed. The functional behavior of such wires has been explored by differential scanning calorimetry (DSC), tensile testing and thermo-mechanical cycling.

Evidence for and the significance of relationships between processing parameters, microstructure and shape memory properties will be presented and discussed.