Nanocrystalline Soft-Magnetic Fe–Zr–B–Cu Composites by Consolidation of Amorphous Powders Coated with Oxide Film through Sol–Gel Process

To improve the soft-magnetic properties of nanocrystalline Fe–Zr–B bulk compacts, nanocrystalline soft-magnetic composites with full density have been fabricated by hot-pressing the amorphous powder coated with SiO2 thin film through the sol–gel process. The nanocrystalline composites exhibit better soft-magnetic properties at higher magnetic induction B m and higher frequency f than the uncoated powder compacts. The saturation magnetization B s, coercive force H c, effective permeability µ e and core loss W h at f=50 kHz and B m=0.2 T were 1.50 T, 39 A/m, 240 and 1200 W/kg, respectively. These results indicate the possibility of producing nanocrystalline soft-magnetic bulk cores with complex shapes for high-frequency AC applications.