New elastomer–Terfenol-D magnetostrictive composites

Several composites, with outstanding magnetostrictive properties, have been synthesized combining a polyurethane elastomer with polycrystalline powders of Terfenol-D. A preferential orientation of the latter was obtained by curing the material in a magnetic field. The morphology of the polymeric matrix can be modified by changing the hard/soft segment ratio of the polyurethane. The influence of the morphology of the polymeric matrix on the composite response has been studied, by following the storage modulus, E′, by DMTA technique. The magnetostrictive response has been studied as a function of the Terfenol-D particle size distribution, and the content of magnetostrictive particles in the composite. The highest response (about 1390 ppm) was obtained for a composite having polyurethane with a 1.5 hard to soft segment ratio, 50% weight of Terfenol-D of 212–300 μm particle size, oriented in a magnetic field of 0.5 T.