Effect of P on amorphous forming ability and magnetic properties of FeSiBC alloy powder

【Objective】 Iron-based amorphous soft magnetic alloys are widely applied in high-frequency electronic devices and power energy storage systems owing to their low loss and high permeability. Nevertheless, conventional iron-based alloys exhibit poor amorphous forming ability, high high-frequency eddy current loss and inferior DC bias resistance, limiting their large-scale engineering promotion. To address these shortcomings and improve the comprehensive soft magnetic properties of FeSiBC alloys, partial Fe substitution by P was adopted for structural modification, aiming to enhance the amorphous forming performance, high-frequency magnetic stability and anti-DC bias capability of the alloys.
【Method】 Spherical FeSiBCP soft magnetic alloy powders were fabricated by a gas-water combined atomization process using high-purity industrial iron, silicon, ferroboron, carbon flakes and ferrophosphorus. The raw materials were melted at 1 600 ℃, then poured at 1 500 ℃. The molten steel was atomized into fine spherical droplets via gas-water synergy, followed by rapid condensation, dehydration, drying and screening. The obtained powders were blended with insulating glue, compacted, cured and wound with copper wires to prepare magnetic core samples with an effective cross-sectional area of 0.1 cm².
【Result】 The gas-water combined atomization process can stably prepare FeSiBCP alloy powders with high sphericity and uniform particle size, featuring good process stability. With the increase of P atomic fraction, the alloy microstructure gradually transforms from crystalline to amorphous state. When the P atomic fraction is 4 at.%, the Fe(SiBC)P alloy realizes complete amorphization, and its coercivity is significantly reduced. In the frequency range of 100~1 000 kHz, the optimized alloy magnetic core delivers an excellent effective permeability of 20.13 and superior high-frequency stability. Moreover, it retains a permeability retention rate of 77.3% under a DC bias field of 100 Oe, showing outstanding anti-DC bias performance. Moderate P doping optimizes the amorphous microstructure of the alloy, which effectively reduces the coercivity, eddy current loss and high-frequency total iron loss of the magnetic powder core.
【Conclusion】 P element modification can effectively improve the amorphous forming ability of FeSiBC alloys and optimize their comprehensive soft magnetic properties. The optimized Fe(SiBC)P amorphous magnetic powder core has excellent high-frequency stability and prominent anti-DC bias performance, which is well applicable to working conditions with high frequency and large DC bias field. The gas-water combined atomization process has good repeatability and batch preparation capability. This study provides a reliable theoretical basis and technical reference for the industrialized production and engineering application of high-performance iron-based amorphous soft magnetic powder cores.