FePBNbCr soft-magnetic glassy alloys with low loss characteristics for inductor cores

Abstract

Fe-based glassy alloys with both high saturation magnetization and low magnetic anisotropy have attracted interest in recent study on Mr. Inoue, 2004, and we have succeeded in developing novel glassy Fe 97− x− y P x B y Nb 2Cr 1 ( x = 5–13, y = 7–15) alloys for an inductor material. The glassy alloy series of Fe 97− x− y P x B y Nb 2Cr 1 ( x = 5–13, y = 7–15) have high glass-forming ability with the large critical thickness of 110–150 μm and low coercivity of 2.5–3.1 A/m caused by the structural homogeneity. The Fe 77P 7B 13Nb 2Cr 1 glassy alloy exhibits the largest critical thickness of 150 μm related to the wide super cooled liquid region and the high saturation magnetic flux density ( B s ) of 1.3 T, both of which are higher than those of the conventional amorphous Fe 75Si 10B 12Cr 3 alloy. Hence, 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 that are annealed at 623 K. In addition, the optimum annealing temperature of 623 K for these glassy alloys was 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.