This proposal serves as the feasibility study for the Additive Manufacturing (AM) of shape memory alloys (SMAs) developed by NASA researchers. The work plan is designed in a way to evaluate the technical advantages of the NASA technology toward AM, modify the ingot production procedure as needed, collect additional required characterization data, investigate commercial routes for reducing the fabrication cost, and to design the next milestones toward powder preparation and process parameter development. After evaluating the IP provided to us by the NASA team, we selected a representative composition for further evaluation. Based on our team experience with the binary NiTi and NiTiHf alloys we expect minor differences in the processing of the selected NiTiHfZr alloys and the other alloys in this category. The work plan is summarized as below:
Samples will be fabricated based on the selected composition via the induction melting technique. A series of heat treatments based on the NASA IP will be performed on the samples. Surface quality, internal defects, and homogeneity of the samples will be evaluated via optical microscopy, SEM, and EDS. Heat-treated samples will be analyzed in a series of thermomechanical and microstructural analysis. The transformation temperatures as well as precipitates will be analyzed using DSC, TEM, and XRD characterization. Thermomechanical properties of the samples will also be evaluated via compression test and isobaric compression test at different stress levels. The homogeneity and potential defects will be analyzed in these steps and the obtained data will be evaluated with reported data by the NASA team.
A comprehensive report will be prepared. The 3Dnol team will request meetings with the NASA researchers to get input on the potential desired properties for the next step. Measured properties as well as any required modifications will be recorded as a major component in fabricating repeatable and predictable AM fabricated parts.
Actuators for deployment mechanism of protective shrouds and seals for booster ring segments of rockets, variable geometry chevrons for jet noise reduction, adaptive components for gas turbines, and more recently torque tubes for shape morphing airfoils, are a few examples. Other applications include actuators for extreme conditions (e.g. actuators used on NASA's Mars Exploration Rover mission), self-actuated actuators (e.g. lightweight self-activated noise mitigation systems for airplanes), and deployable mechanisms such as solar sails.
SMAs hold a significant promise in simplifying and improving various actuation, biomimetic, damping, and energy harvesting systems. One major application is the biomedical implant market through stiffness modulated implants, patient-specific bone implants, and self-expanding cardiovascular stents. The auto industry, oil and gas, and energy applications could also benefit from AM fabricated SMAs.