|Budget Amount *help
¥2,600,000 (Direct Cost : ¥2,600,000)
Fiscal Year 1999 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1998 : ¥1,700,000 (Direct Cost : ¥1,700,000)
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.