Characteristics of Fe-Si-B-P-Cu Nanocrystalline Soft Magnetic Alloy Powders With High Bs

Nanocrystalline soft magnetic alloy powders produced by heat treating amorphous powders are expected to improve properties and miniaturize dust cores because of their low coercive force Hc and high saturation magnetic flux density Bs. By water atomization process, we successfully obtained quenched Fe-Si-B-P-Cu alloy powders with spherical particle shape. The obtained powders have different average particle sizes of 2.0, 3.0, 5.0, and 8.5 μm. After annealing at 723 K, the as-quenched alloy powders are crystallized and Bs of the nanocrystalline alloy powders with Fe_83.3Si₄B₈P₄Cu_0.7 and Fe_84.8Si₂B₁₀P₂Cu_1.2 exhibit high Bs of 1.72 and 1.76 T, respectively. Core loss characteristics of the dust cores are found to be dependent on amorphous stability of the as-quenched powders. Thus, the Fe_83.3Si₄B₈P₄Cu_0.7 nanocrystalline alloy powder with an average particle size of 3.0 μm exhibits the best core loss of 1461 kW/m³ (Bm = 50 mT, f=300 kHz).