Novel Fe(97-x-y)PxByNb2Cr1 Glassy Alloys With High Magnetization and Low Loss Characteristics for Inductor Core Materials

Fe-based glassy alloys with both high saturation magnetization and low magnetic anisotropy have attracted interest recently [1], and we have succeeded in developing novel glassy Fe(97-x-y)PxByNb2Cr1 (x = 5-13, y = 7-15) alloys for an inductor material with high corrosion resistance by added Cr is 1 at%. The glassy alloy series of Fe(97-x-y) PxByNb2Cr1 (x = 5-13, y = 7-15) have high glass-forming ability with wide range super-cooled liquid region of 29-37 K, large critical thickness of 110-150 mu m, and low coercivity of 2.5-3.1 A/m caused by the structural homogeneity. The Fe77P7B13Nb2Cr1 glassy alloy exhibits the largest critical thickness of 150 mu m related to the wide super-cooled liquid region of 36 K and the high saturation magnetic flux density (Bs) of 1.3 T, both of which are higher than those of the conventional amorphous Fe75Si10B12Cr3 alloy. The Fe-P-B-Nb-Cr powder/resin composite core has much lower core loss of 650 kW/m(3) which is approximately 1/3 lower than the conventional amorphous Fe-Si-B-Cr powder/resin composite core annealed at 623 K. Additionally, The Fe-P-B-Nb-Cr glassy alloy has higher corrosion resistance than other system glassy metal of Fe-Si-B-Nb-Cr by having a thick chromium passivation layer. the optimum annealing temperature of 623 K for these glassy alloys is lower than that (723 K) for the ordinary Fe-Si-B-Cr amorphous alloy, which is a significant advantage for the efficiency in mass production of inductor core using soft magnetic glassy alloy powder.