Nanocrystalline soft magnetic Fe-M-B (M = Zr, Hf, Nb), Fe-M-O (M = Zr, Hf,rare earth) alloys and their applications

New soft magnetic nanocrystalline materials in Fe-M-B (M = Zr, Hf; Nb) and Fe-M-O (M = Zr, Hf; rare earth) systems have been fabricated by use of part ial crystallization of melt-spun amorphous phase and sputtering-induced par tial crystallization, respectively. These alloys have a mixed structure of nano-scale alpha-Fe grains and an amorphous phase containing large amounts of M, B and M, O, respectively. This structural property should be a domina nt factor for achieving good soft magnetic properties in both alloys. The F e-M-B ribbons with high Fe content about 90 % exhibit high magnetic flux de nsity of 1.5 to 1.8 T, good soft magnetic properties and very low core loss es at low frequency. On the other hand the soft magnetic Fe-M-O films with high O content of 10 to 35 at.% show high permeability at high frequency ab ove 100 MHz because of their high electrical resistively of 6 to 23 mu Ohm m much higher than those of other conventional soft magnetic alloy films. T he Fe-M-B ribbons should be more suitable for low frequency applications su ch as power transformers and choke coils for active filters for power suppl ies and so on. The Fe-M-O films should be useful for high frequency applica tions such as thin-film inductors and transformers for micro switching conv erters for portable electric equipment and others. (C)1999 Acta Metallurgic a Inc.