Low-loss magnetic powder core, and switching power supply, active filter, filter, and amplifying device using the same

摘要

A magnetic powder core comprises a molded article of a mixture of a glassy alloy powder and an insulating material. The glassy alloy comprises Fe and at least one element selected from Al, P, C, Si, and B, and has a texture primarily composed of an amorphous phase. The glassy alloy exhibits a temperature difference ΔT_x, which is represented by the equation ΔT_x=T_x−T_g, of at least 20 K in a supercooled liquid, wherein T_x indicates the crystallization temperature and T_g indicates the glass transition temperature. The magnetic core precursor is produced mixing the glassy alloy powder with the insulating material, compacting the mixture to form a magnetic core precursor, and annealing the magnetic core precursor at a temperature in the range between (T_g−170) K and T_g K to relieve the internal stress of the magnetic core precursor. The glassy alloy exhibits low coercive force and low core loss.