HDDR処理されたNd-Fe-B系磁石粒子の磁気異方性分布(ハード磁性材料)

概要

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The anisotropy constants K_1 and (K_2-K_3) of anisotropic Nd-Fe-B magnet powders prepared by the modified HDDR process were obtained from torque measurements in magnetic fields of up to 7.2 MA/m.. A value of K_1 = 5.2 × 10^6 J/m^3 was obtained by Fourier analysis of an unsaturated torque curve. In the case of quasrsingle crystal powders, K_1 was 5.9 × 10^6 J/m3, which was closer to the results for Nd_2Fe_<14>B sintered magnets. The magnitude of the anisotropy field H_A distribution in each direction for 2 kinds of anisotropic and isotropic Nd-Fe-B magnet powders prepared by the HDDR process was also determined by Flanders and Shtrikman's method. In powders prepared by the modified HDDR process, the quantity of particles with higher H_A was greater than in those prepared by the ordinary HDDR process in the easy direction, and the angular distribution of H_A was sharp. The easy-axis distribution of particles was less than ± 20 ° for anisotropic powders. In the case of isotropic powders, the easy axes were equally distributed in all directions. The results of experiments showed that Flanders and Shtrikman's method was appropriate for determining the magnitude of H_A and the angular distributions of permanent magnets with high anisotropy.
社団法人日本磁気学会の論文
2005-02-01