The magnetic properties of Fe-Si-B-P-C-Cu nanocrystalline powders were investigated. Fe-Si-B-P-C-Cu powders with a mostly amorphous structure were prepared by an atomization method. The atomized powders were annealed in inert gas atmosphere for nanocrystallization. The Fe84.8Si0.5B9.4P3.5C1Cu0.8 nanocrystalline powder exhibits high Bs of 1.76T, which is appreciably higher than that of conventional Fe-based amorphous powders (1.3 - 1.5 T) and close to that of Fe3.5Si4.5Cr (1.86T) crystalline one. The magnetic loss of toroidal core made of the Fe84.8Si0.5B9.4P3.5C1Cu0.8 nanocrystalline powder is also the lowest compared to that of amorphous and crystalline counterparts. This result indicates that Fe-Si-B-P-C-Cu nanocrystalline powders could contribute in efficiency-improvement as well as miniaturization of soft-magnetic cores.

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Fe-based alloy powders with a high Fe content of about 81 at.% were produced by a gas-atomization technique. Powders of Fe81Si1.9B5.7P11.4 (at.%) alloy showed a good glass forming ability and exhibited unusual high saturation magnetic flux density of 1.57 T. The core-loss property at a frequency of 100 kHz for the compacted core made of the Fe81Si1.9B5.7P11.4 powder is evaluated to be less than 500 kW/m3 under a maximum induction of 100 mT. Moreover, good DC-superposition characteristic of the core was also confirmed. These results suggest that the present Fe-based alloy powder is promising for low-loss magnetic-core materials and expected to contribute in miniaturization of electric parts in the near future.

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