Comparison of Magnetic Properties of Surface-Treated and Untreated Fe and FeNiMo Powders

An innovative preparation route for iron-based soft magnetic materials is presented, focusing on the influence of the mechanical surface treatment of powder particles on their structural and magnetic properties. High-purity Fe (99.98% purity) and FeNiMo (supermalloy) powders were mechanically milled (ball-to-powder ratio of 6:1; 120 min), surface-treated by controlled milling, coated with an inorganic SiO2 insulating layer, and subsequently compacted into ring-shaped specimens. Structural characterization was carried out using optical microscopy and scanning electron microscopy. Magnetic properties were evaluated by hysteresis loop measurements, initial magnetization curves, and coercivity analysis at 200 K. The results demonstrate that mechanical surface treatment improves the homogeneity and continuity of the SiO2 insulating layer. This improvement leads to reduced coercivity from 2100 to 1980 A·m−1 for Fe powders, while FeNiMo powders showed a decrease from 1990 to 1910 A·m−1, along with lower energy losses. The proposed method provides a laboratory-scale approach for studying the influence of powder surface treatment on the magnetic behavior of Fe-based soft magnetic composites.