Thin NiTi wires with reduced thermal hysteresis for shape memory actuators

NiTi wires are successfully employed asthermal actuators: devices able to convert thermal energy into mechanical energy, generating force and displacement. So far, researchers have highlighted the influence of various parameters on shape memory characteristics of the material, such as chemical composition, cold working, heat treatment and cycling. This study is aimed to prove that drawing histories, in particular the number of drawing steps performed to achieve a certain cold working level, are fundamentally important on functional properties of wires. This process parameter involves significant changes in terms of thermal hysteresis width. These alterations are still observable on wires thermo-mechanical cycled, therefore on products ready to be employed for actuators.