Magnetostriction and eddy current loss of bonded giant magnetostrictive particle composites

Rare-earth-iron alloy TbDyFe is an advanced magnetostrictive material to date because of its giant magnetostriction, high energy density, and rapid response at room temperature and low magnetic field. Due to the high sound velocity and eddy current losses of TbDyFe alloy under high frequency, its applications are limited. The bonded giant magnetostrictive materials are expected to exhibit high resistivity to reduce the eddy current loss. In the present study, the bonded giant magnetostrictive materials were prepared by mixing TbDyFe alloy particles with epoxy resin. The electrical resistivity, impedance and eddy current losses of the bonded materials have been primarily analyzed. The optimized magnetostriction is observed to be 723.0×10^-6 at magnetic field of 400 kA/m in the bonded material with particle mass fraction of 90% and particle size of 74-150 μm. TbDyFe particle size and mass fraction show a significant influence on the magnetostriction of the bonded materials. Compared to the advanced oriented TbDyFe alloy, the electrical resistivity is 5 orders of magnitude greater, and the sound velocity is 1/3 lower under the applied magnetic field of 32.7 mT, and the eddy current loss factor is reduced by 90% at 2×10⁵ Hz, and by nearly 50% at 1×10⁷ Hz.