Low-Cost Thin Titanium Shape Memory Alloy Foils by Planar Flow Casting

Aircraft wing morphing by conventional technologies e.g. hinged control surfaces, high list devices and pivoting mechanisms, etc., is heavy and needs elaborate maintenance. Therefore, the current use of mechanical and hydraulic actuators and control system are suffering many drawbacks due to their cost, weight, size, complex design and reliability considerations.

The use of shape memory alloys (SMAs), such as titanium (Ti) SMAs, as an actuator has a numerous advantages over the conventional mechanical and hydraulic systems: simple design as there is no moving parts, lighter, more reliable and able to provide significant displacement and force.  There, however, are two obstacles that have prevented the wider industrial adaption of Ti SMA actuators in the aircraft fields: (1) the slow response and (2) non-uniformly distributed actuation force resulted from the lack of affordable, thin and large size Ti SMA materials.

Thin Ti SMA foils of 10-30 µm thickness, 30mm width and several meters length have been successfully fabricated by a low-cost novel planar flow casting process at CSIRO, which could have the potential to overcome the current SMA drawbacks in term of cost, length, width and thickness. Results of microstructural characterization, thermal analysis and mechanical testing as well as the surface quality for the Ti SMA foil materials will be presented.