Improvement of soft magnetic properties for distinctly high Fe content amorphous alloys via longitudinal magnetic field annealing

•Longitudinal magnetic field annealing improves soft magnetic properties.•Super high Fe content amorphous alloys can exhibit superb softness.•A minimum Hc of 0.8 A/m and a maximum μe of 11 × 103 were obtained.•Optimally annealed ribbon exhibits lowest Hc and stripe magnetic domains. The effects of longitudinal magnetic field annealing on soft-magnetic properties (SMPs) and magnetic domain structure of Fe(82.6-85.7)Si(2-4.9)B(9.2-11.2)P(1.5-2.7)C0.8 amorphous alloys with a distinctly high Fe content of 93.5–95.5 wt% for high Bs were investigated. It was found that longitudinal magnetic field annealing could improve soft-magnetic properties (SMPs) of amorphous alloys effectively, except the one with poor thermal stability. Superb magnetic properties containing a minimum coercivity of 0.8 A/m, a maximum effective permeability of 11 × 103 at 1 kHz and minimum core loss of 0.052 W/kg (at Bm = 0.9 T and f = 50 Hz) were successfully obtained. Domain structures were characterized with a Magneto-optical Kerr Microscope to unveil the mechanism of SMPs improvement. Stripe domains were observed in the annealed high Fe content amorphous alloy ribbons with optimal soft magnetic properties.