Influence of Magnetic Field Annealing Methods on Soft Magnetic Properties for FeCo-Based Nanocrystalline Alloys

The influence of magnetic field annealing methods on soft magnetic properties was investigated by measuring initial permeability μ_i, saturation magnetostriction λ_s, and effective magnetic anisotropy (K) of nanocrystalline (Fe_1-xCo_x)_73.5Si_13.5B₉Nb₃Cu₁ (x = 0.25, 0.5, and 0.75) alloys under different magnetic field thermal treatments. Compared with nonmagnetic field annealing, three magnetic field annealing methods can increase the μ_i of FeCo-based experimental samples, but the impact degree is significantly different. After magnetic field annealing, λ_s was reduced and (K) was enhanced, which can contribute to the increase of μ_i. By comparing three magnetic field annealing methods, we found that the magnetic field nanocrystallization is the most effective magnetic field annealing method to improve the magnetic softness of samples, which could be attributed to a stronger ferromagnetic atomic mobility in the early period of primary crystallization.