Dynamic magnetic characteristics and relaxation of Fe73.5Cu1Nb3Si15.5B7 nanocrystalline alloy under operating temperature and magnetizing frequency

The alternation of dynamic magnetic characteristics with operating temperature and magnetizing frequency in annealed Fe73.5Cu1Nb3Si15.5B7 nanocrystalline alloy core was systematically studied by AC B-H loop tracer and complex permeability approach. It is found that the operating temperature below 160 °C has little influence on core loss when the induction (B) is less than 1.1 T. As B becomes higher, core loss measured at higher temperature becomes larger. The B and remanence (Br) at 80 A/m under power frequency both decline slightly as the temperature goes up. Furthermore, the real part of permeability (μ') increases at first and then decrease with the rise of temperature. The peaks of the imaginary part of permeability (μ'') shift to higher frequency side with decreasing μ' over operating temperature. In addition, the variations of permeability dispersion with the elevated in the operating temperature of the annealed nanocrystalline core are explained by fitting to Havriliak-Negami (H-N) model, revealing that temperature impact on the magnetic relaxation time.