Improved properties of Fe-Ni-Mo soft magnetic composites via particle surface modification

The preparation of soft magnetic composites requires effective surface modification of alloy powder to enhance insulating properties and achieve dense, uniform coating layers. Firstly, the gas-atomized Fe-Ni-Mo powder was surface modified using the atomic layer deposition method, forming a uniform and dense Al 2 O 3 insulating layer. The secondary surface modification of organic polymers further improves the properties of soft magnetic composites. This study systematically evaluates the effects of the primary and secondary surface modification on the properties of powder particles and soft magnetic composites. The primary modification generates an extremely thin insulating layer of approximately 2.5 nm, which increases the particle resistivity by 9 orders of magnitude. The permeability frequency stability of the soft magnetic composites increased from 11.3 % to 96.5 %, resulting in significant core loss reduction. The secondary modification effectively enhances the formability of soft magnetic composites. Optimal permeability of 242.7 at 1 kHz is achieved, maintaining 95.2 % frequency stability up to 1 MHz, while core loss remains below 570 mW cm −3 under 100 kHz/100 mT conditions. The surface treatment method in this work can provide a reference for the surface insulation modification of soft magnetic composites.