Effect of Ca and Al additions on the magnetic properties of nanocrytalline Fe-Si-B-Nb-Cu alloy powder cores

Abstract

The Fe-Si-B-Nb-Cu alloys containing Ca and Al were rapidly solidified to thin ribbons by melt-spinning. The ribbons were ball-milled to make powders, and then mixed with 1 wt.% water glass and 1.5 wt.% lubricant. The mixed powders were burn-off, and then compacted to form toroidal-shaped cores, which were heat treated to crystallize the nano-grain structure and to remove residual stress of material. The characteristics of the powder cores were analyzed using a differential scanning calorimetry (DSC) and a B-H meter. The microstructures were observed using transmission electron microscope (TEM). The optimized soft magnetic properties (µi and Pcv) of the powder cores were obtained from the Ca and Al containing alloys after annealing at 530 °C for 1 h. The core loss of Fe-Si-B-Nb-Cu-based powder cores was reduced by the addition of Ca element, and the initial permeability increased due to the addition of Al element.