Soft Magnetic Properties of Magnetic Cores Assembled With a High Bs Fe-Based Nanocrystalline Alloy

Soft magnetic properties of magnetic cores assembled with Fe81.8Cu1.0Mo0.2Si4B14 nanocrystalline alloy ribbon are discussed. The nanocrystalline alloy ribbon was cast in an amorphous phase by a melt quenching method, and a nanocrystalline phase was obtained by high-heating rate annealing. A medium-size toroidal core assembled with this nanocrystalline alloy ribbon exhibits magnetic flux density B-800 at 800 A/m of 1.74 T, core loss P(16/5)0 at 50 Hz, and at 1.5 T of 0.29 W/kg. A racetrack-shaped core, which includes curved and straight sections in the same core, exhibits core losses at 1.0 T and at 400 Hz and 1 kHz of 1.5 and 5 W/kg, respectively. These core losses are as low as those of Fe-based amorphous alloys. A medium-size toroidal core assembled with this nanocrystalline alloy ribbon, secondarily annealed under a perpendicular magnetic field, exhibits core loss P(2/10)k at 0.2 T and at 10 kHz of 2 W/kg. This value of core loss is one of the lowest values for the metallic magnetic cores, which have a saturation induction B-s higher than 1.5 T. A core assembled with this material can be used in several applications from low to medium frequency ranges. Since this material exhibits a higher B-s and one half of the saturation magnetostriction lambda s of Fe-based amorphous alloys with comparable core losses, the most possible applications are in such applications as distribution transformers and inductors in power electronics.