FePBNbCr Soft Magnetic Glassy Alloys “SENNTIX” with Low Loss Characteristics for Commercial Inductor Cores

Abstract

The inductor for a power supply is expected to have higher efficiency and capability of dealing satisfactorily with large current. Additionally, high corrosion resistance characteristics are also required for commercial inductors in practical use of. Thereby, we focused on Fe-based glassy metal alloys with both high magnetization and low magnetic anisotropy ［1］, and developed the novel glassy metal alloys with a chemical composition Fe97-x-yPxByNb2Cr1. In this glassy metal alloy, 1 at % Cr is the optimum composition for the realization of higher corrosion resistance as well as a high magnetic flux density. The glassy Fe97-x-yPxByNb2Cr1 (x=5-13, y=7-15) alloy exhibits the high glass-forming ability leading to the large thickness of 110-150 μm and low coercive force of 2.5-3.1 A/m due to higher structural homogeneity in wide range of composition. The large critical thickness of this alloy should be caused by the high glass-forming ability (GFA) due to the existence of the super cooled liquid region (Tx) of roughly 30 K. Therefore a Fe77P7B13Nb2Cr1 powder/resin composite core displays a much lower core loss of 650 W/m3 than the conventional amorphous Fe75Si10B12Cr3 powder/resin composite core by approximately 1/3.