高鉄濃度R-Zr-Fe合金の永久磁石としての可能性

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The structural and magnetic properties of iron-rich R-Zr-Fe (R=Nd, Sm) alloys prepared by rapid-quenching method were studied. The presence of zirconium makes it possible to realize a TbCu_7-type crystal structure with a high c/a ratio of more than 0.87. Compounds with a TbCu_7 crystal structure having a c/a ratio as high as 0.87 show a high saturation magnetization of 1.7 T at room temperature. Nitrogenation leads to an expansion of the lattice and gives rise to a remarkable enhancement of the magnetocrystalline anisotropy in the case of Sm. The hard magnetic properties of the nitrogenated materials were improved by additional annealing before nitrogenation. The highest (BH)_<max> value so far obtained for the isotropic Sm-Zr-Fe-Co-N powders is 148 kJ/m^3 with B_r=1.06 T and _iH_c=570 kA/m.
1997-04-01