Optimization of electromagnetic properties for soft magnetic powder cores prepared by gas-atomized FeSiBCuNb powders with continuously distributed the phase structures

The FeSiBCuNb gas-atomized powders (GAPs) show high sphericity, which is conducive to the formation of uniform insulating coating layers. However, it is difficult to obtain completely amorphous GAPs with relatively large particle sizes for Fe-based nanocrystalline alloys. In this work, the raw FeSiBCuNb GAPs with continuously distributed the phase structures are used to prepare soft magnetic powder cores (SMPCs). The effects of annealing process parameters on the average grain size, crystalline volume fraction, magnetic anisotropy constant (K), residual internal stress and magnetic properties of the SMPCs were studied in detail. The results showed that the increase of annealing temperature was more helpful for the magnetic properties of the SMPCs than extension of annealing time, which was due to average magnetic anisotropy constant (K) on coercivity primarily influenced on the SMPCs under the different annealing temperatures. When the annealing temperature is 500 degrees C, heating time is 50 min and holding time is 10 min, the NSMCs achieve relatively excellent magnetic properties: the effective permeability is 29.38 at 100 kHz, the quality factor is 126, the losses are 786 mW/cm3 (20 mT, 1 MHz), and the DC-bias characteristic is 67.28% (100 Oe or 7960 A/m). These results provided the potential for utilization of the raw FeSiBCuNb GAPs with continuously distributed the phase structures.