Frequency and magnetic properties in the range of 10 kHz to 100 MHz for nanocrystal Fe–Co alloy

Fe-based soft magnetic alloy with Co-doping was fabricated by high-energy milling. The X-ray diffraction (XRD) results exhibit a single phased structure, which could be regarded as BCC-like Fe–Co solid solution, was formed. Moreover, it has also been demonstrated that a nanocrystalline Fe–Co alloy was obtained and the evaluated grain sizes were about 7–12 nm. The frequency dependence of the initial permeability and magnetic losses, as well as DC-magnetization measurements, was systematically studied then. The results show that the fn (fn is the frequency when the curve of the No. n sample has a minimum value) shifts to the higher frequency with the increasing Co content in the range of 10 kHz to 100 MHz, while the magnetic losses of the samples decrease with the increasing Co content at the high frequency (800 kHz to 20 MHz). The Co-doping increases the cut-off frequencies of the samples and makes the initial permeability to keep a constant value in a wider frequency range. The corresponding peak value of the initial permeability as function of Co-doping concentration turns to the region of low Co concentration. For the long milling time, the loss apparently decreases beyond 1 MHz.