Magnetic Shape-Memory Foams for Actuators and Other Industrial Purposes
- Technology Benefits
- Inexpensive casting process Actuation stroke 100 times that of piezoelectric actuator materials, but with comparable response time Compact, lightweight, and robust
- Detailed Technology Description
- Polycrystal memory foam for less expensive, more stable actuators #energy #alternative #MEMS #actuator
- *Abstract
-
Magnetic shape memory alloys (MSMAs) are a field of active materials that enable fast, large-strain actuators. Single crystal shape-memory alloys have thus far been utilized; very high (~10%) magnetic-field-induced strains (MFIS) for single-crystal nickel-manganese-gallium (Ni-Mn-Ga) alloys have been measured. However, Ni-Mn-Ga single crystals are brittle and difficult to prepare, thus limiting their commercial potential. Randomly textured, fine-grained, polycrystalline Ni-Mn-Ga alloys are easier to manufacture, but result in near-zero MFIS. Northwestern inventors have overcome these performance limitations by synthesizing the alloy as a polycrystalline foam structure. The foam permits single crystallinity deformation to extend over longer distances, resulting in greater field induced strain (2-4%) – i.e., the foam changes shape in strong magnetic field. This development will allow for the manufacture of actuators using polycrystals, which are less restrictive to produce than the single-crystal variety.
- *Inventors
- David DunandZuexi ZhangPeter MullnerMarkus ChmielusCassie Witherspoon
- *Publications
- Chmielus M, Zhang X, Witherspoon C, Dunand D and Mullner P (2009) Giant magnetic-field-induced strains in polycrystalline Ni-Mn-Ga foams. Nature Materials. 8: 863-866.
- Country/Region
- USA
