Fabrication of Fe-based soft magnetic flake powders for flake-composite magnetic sheet core

摘要

The authors proposed a novel iron-based alloy flakes for composite magnetic sheet core used for beyond MHz switching DC-DC converter.Although the flake powder exhibited higher permeability than that of spherical powder,its coercivity became higher because of the residual stress generated in the flake fabrication process.In this study,in order to reduce the coercivity of the flake powders,the authors investigated the suppression of coercivity increase for the flake powders made from two types of the Fe-based soft magnetic material as the starting material,one was the water-atomized Fe-Si-B-Cr-C amorphous(Fe-AMO)sphere powders and the other was the Fe-Cu-Nb-Si-B nano-crystalline(Fe-NANO)alloy ribbon fabricated by rapid quenching method.From the experimental results,the Fe-AMO flake powders exhibited a coercivity of 438 A/m(5.5 Oe)，and the Fe-NANO flake powders exhibited a coercivity of 119 A/m(1.5 Oe)by introducing annealing process to reduce the internal stress for the milled flakes.