Development of Soft Magnetics Fe-B-C-Si Amorphous Alloys with High Magnetization and Sufficient Amorphous-Forming Ability

Abstract

The amorphous-forming ability (AFA) and the magnetic properties of the amorphous Fe-B-C-Si soft magnetic alloys have been investigated. Though the ternary Fe-B-C alloys exhibit high magnetization, their AFA is poor, which has prevented their practical application. It was confirmed that the addition of Si to the Fe-B-C alloys significantly improves AFA. Furthermore, it has been found that the composition range of the Fe-B-C-Si alloys with sufficient AFA can be identified by focusing on the enthalpy of mixing (ΔHmix) and δ, which is related to the ratio of atomic radius between the constituent elements, of the alloys. The Fe-B-C-Si amorphous alloys that combine the high saturation magnetization of 175−177 A m2/kg with sufficient AFA to produce thick sheets whose thickness of 70 μm or more have been successfully developed by using the relationship between ΔHmix, δ and AFA as a guideline. The Fe-B-C-Si amorphous alloys are expected to be applied to core materials for various magnetic components.