ナノ粒径をもつbcc Fe-Zr-B-Cu合金の磁心特性とその熱的安定性

抄録

A mostly single bcc phase with nanoscale grain size of 10 to 20nm has been found to form by annealing amorphous Fe-Zr-B, Fe-Hf-B and Fe-M-B-Cu (M=Ti, Zr, Hf, Nb and Ta) alloys. It has further been clarified that the newly developed nanocrystalline bcc alloys exhibit high permeability (μe) combined with high saturation magnetization (Bs).
We have subsequently investigated possible application potentials of the bcc alloys. The core loss shows as smaller as 66mW/kg at 1T and 50Hz for a nanocrystalline bcc Fe86Zr7B6Cu1, alloy obtained by annealing for 3.6ks at 873K. This value is 45% and 95% smaller than those for amorphous Fe86Si9B13 alloy and Fe-3.5% Si alloy, respectively, which are presently in use as core materials in electric power transformers. The frequency dependence of core loss for the bcc alloy at 0.2T is almost the same as that for an amorphous Co70.5Fe4.5Si10B15 alloy with Zero magnetstriction. In the frequency range of 10 to 300kHz, the core loss for the bcc alloy is slightly smaller than the Co base amorphous which has been used as core materials in high-frequency transformer. Furthermore, the core losses of the nanocrystalline Fe86Zr7B6Cu1 alloy were also found to have high stability against thermal aging. Thus, nanocrystalline bcc Fe-Zr-B-Cu alloy with the advantages of high Bs, high μe and low core l0ss is expected to be used as a core material in various transformers.