Effects of gas nitridation on microstructures and magnetic properties of Fe3N/Fe soft magnetic composites

Fe 3 N/Fe soft magnetic composites (SMCs) are a kind of promising materials with excellent magnetic properties. In this work, Fe 3 N/Fe core-shell particles are prepared by gas nitriding and then pressed into Fe 3 N/Fe SMCs. The Fe 3 N phase increases with the nitriding time, resulting in the decrease of saturation magnetization and the increase of remanence and coercivity. The saturation magnetization and coercivity of the 5 h nitridated sample are 87.8 emu/g and 13.2Oe, respectively, and the product is identified to be pure Fe 3 N phase. The effective permeability firstly decreases and then increases with the nitridation time. The 5-h nitriding sample shows the best frequency stability, and its permeability decreases from 14.2 at 20 kHz to 4.3 at 590 kHz in a 4mT magnetic field. The core loss, especially eddy current loss, of Fe 3 N/Fe SMCs is obviously decreased with Fe 3 N content. The results show that the properties of soft magnetic composites at high frequency can be improved significantly by nitriding treatment.