Abstract
Shape memory alloys (SMA) are a lightweight and compact option for actuators because of their high energy density capacity and allowing the system weight to be reduced by a fraction of conventional actuators. An SMA processed into wire with a narrow hysteresis and great thermomechanical stability can ease integration into novel actuation designs. These designs can improve the thermomechanical response and reduce the energy usage, weight, and mechanical complexity of the system. Compositionally substituting Ni for Cu in the NiTi SMA system creates an SMA with these characteristics in comparison to binary NiTi SMAs. In this study, a set of NiTiCu SMA compositions were thermomechanically-processed using conventional methods such as rolling and drawing to produce plates, rods, and 0.50 mm diameter wire. Every processing step was characterized to monitor the evolution of microstructure and thermomechanical properties by using various microscopy, spectroscopy, and diffraction techniques. The NiTiCu wires were shape-set using a custom-made device to form small springs with dimensions specified to an actuating device within the reorientation mechanism of a CubeSat. Springs were made from NiTiCu wires and from commercially available NiTi wires, then thermomechanically cycled 50 times to train and compare the thermoelastic properties and actuation response.
