Improvement of soft magnetic properties by simultaneous addition of P and Cu for nanocrystalline FeNbB alloys

The additional effect of P and/or Cu on the structure and the magnetic properties of Fe-Nb-B nanocrystalline soft magnetic alloy tapes with a wide width of 5 mm produced in air was investigated. Although Cu or P addition changes the magnetic softness a little, only the simultaneous addition of 1 at. % P and 0.1 at. % Cu significantly improves the soft magnetic properties of the crystallized alloys. The best magnetic properties (higher permeability than 45x10(3), lower coercivity than 5 A/m, and saturation magnetic flux density of 1.50-1.54 T) were obtained in the compositional ranges of 6.6-6.8 at. % Nb and 8.4-8.8 at. % B with 1% P and 0.1% Cu, and these values are superior to the typical nanocrystallized Fe(84)Nb(7)B(9) alloy prepared in a vacuum. The improvement probably originates from the decrease in the distribution of the alpha-Fe grain size in the crystallized structure by the simultaneous addition. (c) 2007 American Institute of Physics.