High-frequency loss analysis and related magnetic properties of Fe-based amorphous soft magnetic composites with different granularity matches

The regulation mechanism of comprehensive soft magnetic properties for the Fe-based amorphous powder cores with different granularity match schemes used in high-frequency applications was investigated in detail. Herein, the FeSiBCCr amorphous particles with three different average particle diameters of 2.20 (P1), 12.52 (P2), and 27.65 μm (P3) were employed. Based on the establishment of the loss separation model, the total core loss (Pcv, at 25–900 kHz, 0.1 T) was divided into hysteresis loss Ph, eddy current loss Pe, and residual loss Pr. The particle size matching, which can directly affect the core's density under constant parameters, has a significant impact on the magnetic properties of powder cores. With the increase in the density induced by varying granularity match scheme, the real part of complex permeability μ′ increases, while Pcv, Ph, Pr, and DC-bias property of powder core show a reducing trend. This is attributed to the decrease in air gap in the composites, which is closely related to the pinning of domain movement and coercivity. The powder core with the granularity match scheme of 30:60:10 for P1%:P2%:P3% exhibits the excellent comprehensive magnetic properties including a stable μ′ of 41.2 up to 3 MHz, high DC-property of 74.3%@100 Oe, and low Pcv of 10389.5 kW/m3 at 900 kHz, 0.1 T. This work offers insights into regulating magnetic properties for the powder core toward high-frequency applications, particularly referring to the granularity matching.