Development of high performance metallic magnetic core using new magnetic phenomenon

An excessive annealing of amorphous Fe-Cu-Nb-Si-B ribbons precipitated Fe锡D22锡D2B fine crystallites in the nanostructured Fe-Cu-Nb-Si-B mother phases.The precipitated crystallites played the role of pining sites of domain walls，and reduced the permeability of the ribbons down to approximately300 without a significant increase in magnetic loss.The magnetic loss of the developed ribbons is comparable with that of Mn-Zn ferrite and an amorphous cut core with air-gaps，and the saturation magnetization of the ribbons is approximately three times as high as that of ferrite.In addition，the permeability of the ribbons can be adjusted to a desired value after preparation of a core.Further investigation on magnetic properties under a dc-biased field，however，revealed that the magnetic loss of the prepared ribbons increases significantly under a dc-biased field，and that the magnetization rotation mode is preferred for reducing magnetic losd for reducing magnetic losed field。Thus，nanostructured Fe-Cu-Nb-Si-B ribbons in which the magnetization changes by its rotation were also developed by using the creep-induced anisotropy，and a gap-less magnetic core with low loss and low permeability was prepared from the prepared ribbon。Actually，the magnetic loss of the prepared core did not increase even under a dc-bias field.The saturation magnetization of the prepared core is approximately three times as high as that of ferrite，and the constancy of its permeability under a dc-bias field is superior than that of a ferrite core.In addition，the magnetic loss of the core is2/3 of that of a ferrite core(100 kHz，0.1T，under a dc-bias field)。Therefore，the developed core is considered to be applied to electronic devices。

An excessive annealing of amorphous Fe-Cu-Nb-Si-B ribbons precipitated FeィイD22ィエD2B fine crystallites in the nanostructured Fe-Cu-Nb-Si-B mother phases. The precipitated crystallites played the role of pining sites of domain walls, and reduced the permeability of the ribbons down to approximately 300 without a significant increase in magnetic loss. The magnetic loss of the developed ribbons is comparable with that of Mn-Zn ferrite and an amorphous cut core with air-gaps, and the saturation magnetization of the ribbons is approximately three times as high as that of ferrite. In addition, the permeability of the ribbons can be adjusted to a desired value after preparation of a core.Further investigation on magnetic properties under a dc-biased field, however, revealed that the magnetic loss of the prepared ribbons increases significantly under a dc-biased field, and that the magnetization rotation mode is preferred for reducing magnetic loss under a dc-biased field. Thus, nanostructured Fe-Cu-Nb-Si-B ribbons in which the magnetization changes by its rotation were also developed by using the creep-induced anisotropy, and a gap-less magnetic core with low loss and low permeability was prepared from the prepared ribbon. Actually, the magnetic loss of the prepared core did not increase even under a dc-bias field.The saturation magnetization of the prepared core is approximately three times as high as that of ferrite, and the constancy of its permeability under a dc-bias field is superior than that of a ferrite core. In addition, the magnetic loss of the core is 2/3 of that of a ferrite core (100kHz, 0.1T, under a dc-bias field). Therefore, the developed core is considered to be applied to electronic devices.