（Department of Functional Material，Central Iron & Steel Research Institute,Beijing 100081,China）
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DOI:
10.7502/j.issn.1674-3962.2013.02.01
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Abstract:
In this paper, we review recent research advance on coercivity mechanism of high performance NdFeB permanent magnets. Influence of fabrication process on the coercivity of the magnets is discussed. In particular, the correlation between microstructure and coercivity is investigated for the magnets prepared by using binary main phase alloy technique. The coercivity mechanism of the magnets prepared by traditional powder metallurgical method or binary alloy technique is based on the starting field theory, and the theoretical result is consistent with the experimental one. Furthermore, the formation mechanism of magnetic anisotropy of hot deformed NdFeB magnets is also discussed. The evolution of magnetic domains of sintered and hot deformed NdFeB magnets during thermal demagnetization process is presented. High performance anisotropic nanocomposite NdFeB magnets with (BH)m of 424 kJ/m3 are prepared. The formation of anisotropy of the magnets is expected as the anisotropic grow up of grains and their rotation and slicing. The magnetic microstructures of the magnets are typical interaction domains. The results show that both microstructures and magnetic properties are strongly correlated to optimum coercivity mechanisms for NdFeB magnets.