Chemical coating of crystalline-Fe/amorphous-Fe core-shell structured composites and their enhanced soft magnetic properties

New-type crystalline-Fe/amorphous-Fe core-shell structures with greatly-improved soft magnetic performance have been synthesized from coating micron-sized Fe powders with amorphous micrometer-thick Fe layers using a facile chemical coating method. Surface-oxidized amorphous Fe layers are uniformly coated upon the surfaces of high-purity Fe particles, which results in their high saturated magnetization (204.6 A m² kg⁻¹) and high compacted density (7.42 g/cm³) in these crystalline-Fe/amorphous-Fe composites. For metal-based soft magnetic composites used in high-power applications, it is always an important goal to accomplish increased magnetic inductions along with reduced core loss. In the present work, excellent soft magnetic performance containing high inductions, reduced core loss and desirable frequency-dependent magnetic characteristics is successfully achieved in fully compressed crystalline-Fe/amorphous-Fe composites due to higher resistivity of amorphous Fe shells, which promises their latent utilization for high-power metal-based magnetic devices.