Effects of Non-field Annealing and Magnetic Field Annealing on the Soft Magnetic Properties of Ni-Doped FINEMET Cores

Adding trace Ni elements and annealing in a magnetic field improves the soft magnetic properties of the Finemet. After changing the Ni content to control the composition of the alloy system and change the pitch of stripes of the magnetic domains, Fe_73.5Si_14.7B_7.6Nb₃Cu₁Ni_0.2 nanocrystalline ribbon with excellent soft magnetic properties was obtained. In this work, transverse magnetic field annealing (TA) was performed on Fe_73.5Si_14.7B_7.6Nb₃Cu₁Ni_0.2 nanocrystalline ribbon cores (NRCs), and the magnetic properties and magnetic domain structure were compared in detail with those after non-field annealing (NA), and the mechanism of the improvement of soft magnetic properties by TA was elucidated. The soft magnetic properties of the cores were adjusted by varying the Ni composition, annealing temperature, and magnetizing temperature. The experimental results show that the core loss (P_s) of the NRCs is reduced by 24.76% (100 kHz, high frequency) and the coercivity (H_c) is 0.854 A/m after 30 min of TA at 400°C compared to the NA sample. TA optimizes the soft magnetic performance of NRCs by optimizing the domain structure and broadening the size of the domain. These results can provide a good guide for optimizing the performance of NRCs with low P_s at high frequency.