Fe-Rich Soft Magnetic FeSiBPCu Hetero-Amorphous Alloys with High Saturation Magnetization

Abstract

Magnetic properties are perhaps the most remarkable and unique properties of Fe-based amorphous alloys. To obtain high saturation magnetization, high Fe content is preferred. However, there is a strict upper limit of Fe content for the formation of a single amorphous structure with good magnetic softness. Fe-based amorphous alloys with high Fe content over the limit have an as-quenched structure consisting of coarse � -Fe grains in an amorphous matrix, which inevitably results in inferior magnetic softness. We have studied the effect of P and/or Cu additions on the microstructure of Fe-based amorphous alloys with high Fe content. The � -Fe grain size and the coercivity (Hc) decrease by the simultaneously adding P and Cu. The Fe-rich FeSiBPCu alloys with the optimized composition have an extremely small � -Fe-like phase of about 3 nm or smaller in a diameter, exhibits the higher Js of about 1.67 T than that of the typical Fe-based amorphous alloy and show the low coercivity (Hc) of about 4 Am � 1 in an as-quenched state. [doi:10.2320/matertrans.ME200831]