Magnetic properties and oxygen content of nanocrystalline FeCuNbSiB alloy annealed in hydrogen and air

Soft magnetic properties and distribution of oxygen are investigated for the nanocrystalline Fe73.5Cu1Nb3Si13.5B9 alloy annealed in hydrogen and air respectively by means of magnetic measurements, X-ray diffraction, Auger-energy-spectra and X-ray photoelectron analysis. The oxygen content at the surface of the strips can be as high as 39 at. % after air-annealing. The oxygen is concentrated mainly in the surface layer up to 30 nm in form of Fe2O3 and SiO2. Excellent magnetic properties can still be reached (except for initial permeability mu(o)) by air-annealing. The optimum temperature for the air-annealing decreases by 40 degrees C than that of hydrogen-annealing.