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 partial crystallization of melt-spun amorphous phase and sputtering-induced partial crystallization, respectively. These alloys have a mixed structure of nano-scale α-Fe grains and an amorphous phase containing large amounts of M, B and M, O, respectively. This structural property should be a dominant factor for achieving good soft magnetic properties in both alloys. The Fe-M-B ribbons with high Fe content about 90% exhibit high magnetic flux density of 1.5 to 1.8 T, good soft magnetic properties and very low core losses 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 above 100 MHz because of their high electrical resistively of 6 to 23 μΩm much higher than those of other conventional soft magnetic alloy films. The Fe-M-B ribbons should be more suitable for low frequency applications such as power transformers and choke coils for active filters for power supplies and so on. The Fe-M-O films should be useful for high frequency applications such as thin-film inductors and transformers for micro switching converters for portable electric equipment and others.