Influence of particles size fraction on magnetic properties of soft magnetic composites prepared from a soft magnetic nanocrystalline powder with no synthetic oxide layer

Soft magnetic composites (SMCs) are usually prepared from microcrystalline Fe, Fe-Si or Fe-Si-Al powders. Other powders, including nanocrystalline ones, are relatively rarely used. The objective of this work was to prepare SMCs from milled Fe-Si-B-Nb-Cu nanocrystalline ribbon and study their magnetic properties. These SMC cores exhibited very low coercivity and, despite no synthetic oxide layer, relatively high resistivity. A combination of these properties resulted in exceptionally low core loss at low frequency and in some initial tests at higher frequencies. Moreover, the influence of powder size fraction on the magnetic properties was also investigated, leading to a conclusion that the use of coarser particles resulted in higher permeability. Further increase in permeability was achieved by mixing the coarsest powder size fraction with the finest one. The presented results show a promising future for this kind of materials.