An alloy first made nearly two decades ago by the U. S. Navy could provide an efficient new way to produce electricity. The material, dubbed Galfenol, consists of iron doped with the metal gallium. In new experiments, researchers from UCLA, the University of North Texas (UNT), and the Air Force Research Laboratories have shown that Galfenol can generate as much as 80 megawatts of instantaneous power per square meter under strong impacts. The team describes the findings, which could lead to the development of wireless impact detectors and other applications, in a paper in the Journal of Applied Physics.
Galfenol is a magnetoelastic material—one in which the state of magnetization can be changed by squeezing, pushing or otherwise deforming the material. Conversely, when exposed to a magnetic field, magnetoelastic materials respond by changing shape. If the materials are prevented from deforming—for example, by being held in a clamp—they instead will generate a large force.
"In general this means a magnetoelastic material can convert mechanical energy into magnetic energy, and vice versa," explained John P. Domann, a mechanical engineering graduate student at UCLA and first author of the paper. Galfenol converts energy with high efficiency; it is able to turn roughly 70 percent of an applied mechanical energy into magnetic energy, and vice versa. (A standard car, by contrast, converts only about 15 to 30 percent of the stored energy in gasoline into useful motion.) Significantly, the magnetoelastic effect can be used to generate electricity. "If we wrap some wires around the material, we can generate an electrical current in the wire due to a change in magnetization," Domann said.
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