Fabrication of amorphous soft magnetic powder cores with low loss and high DC bias performance by controllable heat treatment process

Heat treatment can effectively reduce the hysteresis loss of magnetic powder cores, but research on amorphous powder cores remains limited. In this study, FeSiBCr/ZnO powder cores with low loss and high DC bias performance were prepared by gradually heating and controlling the holding time. The ZnO insulating layer reduced eddy current loss, while stepwise heating minimized residual stress, thereby lowering hysteresis loss. After annealing at 445 ℃ for 1 h, the hysteresis loss is reduced to 57.5 mW/cm³, representing a 66.3% reduction compared to that at 325 °C. Holding times of 0.5 to 3 h yielded losses of 75, 74, 67, and 66 mW/cm³, showing extended times further reduce losses. After annealing at 405 ℃ for 1 h, the loss of FeSiBCr powder core is 292.5 mW/cm³ (1000 kHz, 20 mT) and the DC bias is 79%. This work provides key insights for optimizing amorphous core annealing to minimize losses.