Surface crystallization and magnetic properties of FeCuSiBNbMo melt-spun nanocrystalline alloys

Abstract Fe 82 Cu 1 Si 4 B 11.5 Nb 1.5 −x Mo x ( x = 0, 0.75 and 1.5 at. %) nanocrystalline alloys were prepared using a melt-spinning technique and the effects of Mo content on thermal stability, soft magnetic properties and microstructure evolution were investigated. It was found that the Mo addition can improve the amorphous-forming ability and inhibit surface crystallization in a low vacuum atmosphere which may be due to better oxidative resistance. All the alloys exhibited excellent soft-magnetic properties with low coercivity of 8.9–10.8 A/m, high effective permeability of 11,500–11,900 at 1 kHz and high saturation magnetic flux density of 1.67–1.72 T after annealing at optimal annealing conditions. In addition, the alloys containing Mo have better transient effective permeability stability with increase in frequency. Decreasing the melt-spinning wheel speed can widen the annealing temperature range for Fe 82 Cu 1 Si 4 B 11.5 Nb 1.5 ribbon. Results indicate that these soft-magnetic nanocrystalline materials have good manufacturability for industrial production.