Enhanced soft magnetic properties of Fe-based amorphous powder cores by longitude magnetic field annealing

The longitude magnetic field annealing on the soft magnetic properties of Fe-based Fe78Si9B13 amorphous powder cores were investigated. The magnetic properties of powder core greatly change when annealed under longitude magnetic field. With the increase of magnetic field intensity, the permeability of annealed powder core further increase. The core shows an enhanced effective magnetic permeability of 66 after longitude magnetic field annealing at an applied field of 30 Oe and temperature of 400 degrees C, which is attributed to the relief of internal stress and the variation of atomic structure. The permeability was improved by 8% and the frequency stability of FeSiB amorphous powder core is up to 2 MHz. The core loss decreases obviously and DC bias property stays at a same level compared with zero field treatment with the increase of magnetic field intensity. For the powder cores, the core loss ranges from 90 to 180 W/kg at 50 mT and 100 kHz, and DC bias property reaches over 70% at 100 Oe. This work provides a novel approach to improve permeability for Fe78Si9B13 powder cores and also validates the application prospect of powder core in the work condition of different ripple currents, different loads and a wide frequency range (10 kHz-2 MHz). (C) 2017 Elsevier B.V. All rights reserved.