Intergranular insulating reduced iron powder-carbonyl iron powder/SiO2-Al2O3 soft magnetic composites with high saturation magnetic flux density and low core loss

•The novel soft magnetic composites (SMCs) with better magnetic performance were fabricated.•The mechanism of lessened hysteresis and eddy current loss in SMCs at low frequency was revealed.•It provides a facile preparation method and an effective regulatory mechanism for SMCs.