Development of Rare-Earth・Iron・Boron system exchange coupling type bonded magnet materials with high quality heat-resistant.

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The melt-spun ribbons of Didymium-Fe-B and Pr-Fe-B system alloys were prepared by single roller rapid-quenching method. The effects of composition, wheel velocity and heat-treatment on the magnetic properties were investigated. And some properties of bonded magnets prepared by using these ribbons were examined. The sunmnaly of the experimental results is following.In Didymium-Fe-B alloy system, the melt-spun ribbons of Didymium_<12.5>Fe_<68>Co_<10>Nb_1V_1Tb_<0.5>B_7 prepared at a wheel velocity of 17.5 m/s were crystallized by heat treatment. The optimum heat treatment condition was found to be at 600℃ for 5 min. The values of (BH)_<max> and H_<cJ> amount to 103.6 kJ/m^3, 1628.0 kA/m, respectively. The temperature coefficients of J_r and H_<cJ> for the crystallized ribbons were α (J_r)_<ave>=-0.03 %/℃(reversible) and α (H_<cJ>)=-0.37 %/℃(irreversible) for the temperature range 25 to 125℃. The compression molded Didymium_<12.5>Fe_<68> Co_<10>Nb_1V_1Tb_<0.5>B_7 isotropic bonded magnet, p … More repared by using the ribbons annealed at 600℃ for 5 min, achieve the (BH)_<max> of 66.2 kJ/m^3. The density amount to 6.32 Mg/m^3. At 150℃ irreversible losses of -2.50 % result.In Pr-Fe-B system alloys, melt-spun ribbons of Pr_xFe_<91.5-x-y-z>Co_yTi_<1.5>B_zSi_<0.5> (x = 10.0〜13.0, y = 8.0〜12.0, z=7.0〜14.0) alloys were prepared by the single roller liquid rapid-quenching method, and the effects of composition, wheel velocity and annealing condition on the magnetic properties were studied. The optimum preparation conditions and some of the properties were as follows : composition : Pr_<11>Fe_<68.5>Co_8Ti_<1.5>B_<10.5>Si_<0.5> ; wheel velocity : 10.0 m/s and annealing condition : 650℃ for 0 min in Ar atmosphere ; magnetic properties J_r=0.8 T (, H_<cJ>=1570 kA/m, H_<cB> = 550 kA/m, (BH)_<max> = 111.2 kJ/m^3, H_k/H_<cJ>×100 = 24.9%, α(J_r) =-0.04%/℃, α (H_<cJ>)=-0.37%/℃ and T_c = 403℃. From a TEM observation, the average particle size of this ribbon was found to be about 23 nm. The compression molding isotropic bonded magnets were prepared by using Pr_<11>Fe_<68.5>Co_8Ti_<1.5>B_<10.5>Si_<0.5> ribbons annealed at 600℃ for 5 min. The magnetic properties of this bonded magnet were J_r = 0.60 T (6.0 kG), H_<cJ> = 1530 kA/m, H_<cB> = 420 kA/m and (BH)_<max>=66.8 kJ/m^3. The irreversible losses of Pr_<11>Fe_<66.5>Co_<10>Ti_<1.5>B_<10.5>Si_<0.5> and Pr_<11>Fe_<64.5>Co_<12>Ti_<1.5>B_<10.5>Si_<0.5> bonded magnets were smaller than that of MQP-O one at 150℃. Less