Innovative Shape Memory Metal Matrix Composites

Shape memory alloys (SMAs) are metals that can return to their original shape following thermal input. They are commonly used as functional materials in sensors, actuators, clamping fixtures and release mechanisms across industries. SMAs can suffer from dimensional/thermal instability, creep, and/or low hardness, resulting in alloys with little to no work output in the long term. To combat these deficiencies, NASA has developed a process of incorporating nanoparticles of refractory materials (i.e., carbide, oxide, and nitride materials with high temperature resistance) into the alloys. Using various processing methods, the nanoparticles can be effectively mixed and dispersed into the metal alloys as shown in the figure below. In these processes the SMA and refractory material powder is mixed and the refractory nanoparticles incorporated through extrusions, melting, or directly used in additive manufacturing to create parts for applications across the aerospace, automotive, marine, or biomedical sectors. The nanoparticle dispersion is a controllable method to strengthen the SMAs, increasing the hardness of the alloys, reducing the impact of creep, and improving the overall dimensional and thermal stability of the alloys. The related patent is now available to license. Please note that NASA does not manufacture products itself for commercial sale. Researchers at the NASA Glenn Research Center have developed a new family of shape memory alloys that are strengthened by incorporating ceramic or refractory nanoparticles into the alloy. The resulting material is referred to as a shape memory metal matrix composite or SM3C. The new dispersion-strengthened metals retain the useful properties of the shape memory alloy without the typical deficiencies. Specifically, the dispersoids improve the material’s dimensional and thermal stability while increasing both the creep resistance and hardness. The SM3C material is compatible with multiple manufacturing processes including additive manufacturing, mechanical alloying, or other conventional processes like melting and extrusion. Parts produced using the SM3C may be used in various aerospace, marine, or automotive applications as actuators or in the biomedical field as surgical tools and orthopedic implants.