Structure and magnetostriction of FeGaTb / epoxy resin composites with different particle sizes

This paper presents the fabrication process and results of studies of the microstructure and magnetic properties of magnetostrictive Fe-Ga-Tb composites. The samples were prepared from powder particles of the (Fe80Ga20)99.85Tb0.15 alloy, which were annealed at a temperature of 750°C for 3 hours and then sieved and distributed into the following fractions: up to 50, 50 –100, 100 – 200, and 200 – 300 μm. When obtaining magnetostrictive composites, epoxy resin was used as a binder and insulator in a powder-to-epoxy resin weight ratio of 2 to 1. The microstructure and magnetic properties of the powders and composites were studied using scanning electron microscopy and vibration magnetometry. The field dependence of magnetostriction and the position of the strain gauge, caused by the inhomogeneity of the samples, was established. A trend toward increasing magnetostriction with increasing particle size was observed. It was found that the longitudinal magnetostriction increased by 10 – 50 % with increasing particle size, reaching ≈45 ppm in regions with high particle concentrations. This occurs because increasing particle size alters their domain structure, leading to the appearance of a larger number of 90° domains, the motion of which is the primary contributor to the linear magnetostriction of Fe-Ga at the microscopic level. These results demonstrate the important role of particle size in shaping the functional properties of magnetostrictive Fe-Ga-based composites.

1. Russian Science Foundation - 25-73-00050