Nd-Fe-Co-B-C系急冷薄帯磁石の諸特性

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概要

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• Melt-spun ribbons of Nd-Fe-Co-B-C system alloys were prepared by the single roller rapid-quenching method. The effects of composition, substrate surface velocity and heat treatment on the magnetic properties were studied. The crystallized ribbons from amorphous state were used as the raw materials of the bonded magnets, and these magnets were prepared by compression molding technique. A maximum energy product of 140.5 kJ/m^3 was obtained for Nd_<11>Fe_<72>Co_8 (B_<0.5>C_<0.5>)_9 alloy ribbon prepared at a substrate surface velocity of 17.1 m/s. The amorphous Nd_<11>Fe_<72>Co_8 (B_<0.5>C_<0.5>)_9 ribbons prepared at a substrate surface velocity of 20.7 m/s were crystallized by heat treatment, and the optimum heat condition was found to be at 600℃ for 30 min, then the value of (BH)_<max> was 138.5 kJ/m^3. From TEM micrograph, the fine grains of the ribbons crystallized from the amorphous state were from 20 to 40nm. The Curie temperature of an amorphous phase was 273℃, and that of fine crystalline phase was 391℃. The temperature coefficients (from 25 to 125℃) of B_r and H_<cJ> for the ribbons crystallized of Nd_<11>Fe_<72>Co_8 (B_<0.5>C_<0.5>)_9 alloy were -0.105 %/℃ (reversible) and -0.394 %/℃ (irreversible), respectively. The spin reorientation of this sample was observed at below -135℃. The value of (BH)_<max> for Nd_<11>Fe_<72>Co_8 (B_<0.5>C_<0.5>)_9 bonded magnet prepared by using the ribbons heated at 600℃ was 90 kJ/m^3, and then this bonded magnet density was 6.30 Mg/m^3 (L/D=0.77). The irreversible flux losses of bonded magnets at 125℃ were less than 4.5 %.

著者

• 山元 洋

  School of Engineering, Meiji University

• 山口 岳人

  School Of Science And Technology Meiji University:(present Adress)canon Co. Ltd.

• 児玉 巌

  School of Science and Technology, Meiji University

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