Anisotropic characteristic in HDDR Nd₁₃Fe₈₀B₇

Jingzhi Han, Aizhi Sun, Yaofu Xiao, Xubo Liu, and Run WangMaterials Science and Engineering School, University of Science and Technology Beijing, Beijing 100083, China

摘 要：<正> The function of disproportionation and desorption stages of hydrogenation-disproportionation-desorption-recombination （HDDR） process in the formation of magnetic anisotropy was studied. The results showed that degree of anisotropy （DOA） of Nd13Fe80B7induced by appropriate HDDR process is comparable with that of Nd13Fe80-xB7Mx（M=Co, Zr or Ga）, however, the moderate coercive force of Nd13Fe80B7 magnetic powder led to an undesirable （BH）max of 104 kJ/m3 in bonded magnet. Experiments demonstrated that a relatively short disproportionation time, combined with a high desorption temperature and slow desorption rate, during HDDR process is beneficial to anisotropy attainment, but HDDR Nd13Fe80B7 magnetic powder becomes isotropic if the disproportionation time is longer than a certain period. This phenomenon strongly indicated that the origin of anisotropy in NdFeB-type HDDR material is contributed by disproportionation stage. XRD （X-ray Diffraction） analysis and TEM （Transmission Electron Microscope） observatio

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