| Abstract |
| The melt-spun Fe_(73.5)Cu₁Nb₃Si_(13.5)B_(9) ribbons so called Finemet alloy were annealed in the temperature range of 490 to 610℃ for 1 h and milled by using a planetary ball mill into the powders with the size of 250~850 sm. Then the powder cores were produced through the blending of the magnetic powders with the 5 wt% of ceramic insulator and cold compaction. Further the annealing responses of magnetic, electrical properties and microstructure were investigated. At the annealing temperature of 550℃, the microstructure was transformed from amorphous to crystalline a-Fe phase with the grain size of 10.7 nm, and the electrical resistivity of 117 μΩ-㎝ was obtained. At the same time, the effective permeability and quality factor reached 120 and 50, respectively, and the permeability persisted up to about 500 kHz. Moreover the core loss at the frequency of 50 kHz and the magnetic induction of 0.1 T was about 300 mW/cm³. These magnetic properties were comparable to the conventional powder core materials such as MPP(molybdenum permalloy powder), Sendust etc. However the dc bias characteristics represented by the permeability stability upon dc magnetic field superposition were found to be unsatisfactory. (Received February 16, 2004) |
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| Key Words |
| Ultrafine grain structure, Ball milling, Annealing temperature, Powder core, Dc bias characteristics |
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