This past fall, ME Professor Chris Weinberger’s groundbreaking research in shape memory materials was published by the prestigious journal, Nature Communications.
The article, entitled, “Superelasticity and Cryogenic Linear Shape Memory Effects of CaFe2As2,” was recognized for its discovery of an innovative shape memory material which has the potential to advance deep space exploration, and eventually revolutionize the shape memory industry.
Conventional shape memory alloys are solid state actuators and are used in a wide range of industrial applications replacing traditional methods of actuation including hydraulics, pneumatics, and other motor-based actuators; however, there are a number of practical issues associated with shape memory alloys that include dimensional instability, fatigue, and limitations to functionality under extreme temperatures. With this knowledge, it was desirable to identify alternative shape memory materials.
A group of 12 researchers, including Dr. Weinberger, demonstrated that a new class of materials are capable of both shape memory properties as well as superelasticity. CaFe2As2, a material similar to conventional shape memory alloys but less susceptible to dimensional instabilities and fatigue, showed promising results. The material was also known to be a superconductor that could undergo a temperature dependent phase transition. When CaFe2As2 was put to the test and cycled through 100 actuations with no changes in properties, the group was optimistic.
Final results concluded that CaFe2As2 exhibited unparalleled results when compared with any currently known shape memory material. In addition, the operation temperature of the shape memory effect is extremely low, between 50 and 100K, suggesting that this type of shape memory material could be developed for space applications.
Perhaps more importantly, the discovery of superelastic and shape memory properties of CaFe2As2 has the potential for advancing several industries, not just deep space exploration. CaFe2As2 properties can be tuned, allowing for customization of the chemical composition of the material which would allow engineers to tailor the actuation temperatures and the actuation work. Furthermore, since there are over 400 known compounds that are similar to CaFe2As2, this research has demonstrated that this discovery only scratches the surface.