Improving the glass formation ability and magnetic properties by Nb in Fe-Si-B-P-Cu-Nb nanocrystalline alloys

Abstract Fe-based nanocrystalline alloys with high saturation flux density (Bs) are highly desired for the miniaturization of electronic devices. However, the glass forming ability (GFA) and the temperature window of annealing processing of the high Fe content nanocrystalline alloys need to be improved to satisfy the industrial production. In this work, the influence of Nb on the GFA, crystalline behavior, soft magnetic properties of melt-spun Fe86.3-xSi1.3B8.9P3Cu0.5Nbx (0 ≤ x ≤ 4) alloys have been comprehensively investigated. It has been found that full amorphous structure can be obtained when the content of Nb is more than 3 at. %, and Nb may play a critical role in the optimization of crystalline processing. It has been also demonstrated that α-Fe (Si) grains were obviously refined by Nb so as to result in the decease of coercivity (Hc). In this work, Fe82.3Si1.3B8.9P3Cu0.5Nb4 ribbon exhibits an Hc of 4.2 A/m after relaxation, and a Bs of 1.54 T after annealed at 500℃, respectively, which are comparable to those of NANOPERM alloys.