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Effects of orientation and interaction of grains on coercivity for sintered NdFeB magnets

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Abstract

The coercivity of NdFeB magnets is determined by the coercivity of individual grains and the interaction between the grains composed of the magnets. The coercivity of individual grains and the intergrain interaction depend on the degree of the grain alignment, “tanθ type” Gaussian function is applied to describing the degree of the grain alignment. According to different coercivity mechanisms, there are different formula on the coercivity and the angular dependence of coercivity. The interaction between grains can be classified as the long-range magnetostatic interaction and the exchange-coupling interaction of neighboring grains. For the sintered magnet, the grain size is large and the grain boundaries are mostly separated by the non-magnetic phase. So, the long-range magnetostatic interaction is much stronger than the exchange coupling interaction and it makes the coercivity of the magnet composed of misaligned grains be bigger than that of the magnet composed of ideally aligned grains. The effects of coercivity of individual grains and the intergrain interactions are taken into account, and the starting field theory is in agreement with the experimental result for the coercivity of sintered NdFeB magnets.

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References

  1. Kronmüller, H., Durst, K. D., Sagawa, M., Analysis of the magnetic hardening mechanism in ReFeB permanent magnets,J. Magn. Magn. Mater., 1988, 74: 291.

    Article  Google Scholar 

  2. Givoid, D., Lu, Q., Rossignol, M. F. et al., Experimental approach to coercivity analysis in hard magnetic materials,J. Magn. Magn. Mater., 1990, 83: 183.

    Article  Google Scholar 

  3. Kou, X. C., Kronmüller, H., Givord, D. et al., Coercivity mechanism of sintered Pr17 Fe75 B8 and Pr17 Fes53 B30 permanent magnets,Phys. Rev. B, 1994, 50: 3849.

    Article  Google Scholar 

  4. Gao, R. W., Zhou, S. Z., Zhang, D. H. et al., Coercivity and its dependence on orientation magnetic field in NdFeB sintered magnets,J. Appl. Phys., 1995, 78: 1156.

    Article  Google Scholar 

  5. Gao, R. W., Zhang, D. H., Li, H. el al., Effects of the degree of grain alignment on the hard magnetic properties in sintered Nd-Fe-B magnets,Appl. Phys. A, 1998, 67: 353.

    Article  Google Scholar 

  6. Schrefl, T., Schmidts, H. F., Fidler, J. et al., The role of exchange and dipole coupling at grain boundaries in hard magnetic materials,J. Magn. Magn. Mater., 1993, 124: 251.

    Article  Google Scholar 

  7. Kronmüller, H., Fischer, R., Hertel, R. et al., Micromagnetism and the microstructure in nanocrystalline materials,J. Magn. Magn. Mater., 1997, 175: 177.

    Article  Google Scholar 

  8. Fukunaga, H., Inoue, H., Effect of intergrain exchange interaction on magnetic properties in isotropic Nd-Fe-B magnets,Jpn. J. Appl. Phys., 1992, 31: 1347.

    Article  Google Scholar 

  9. Fidler, J., Schrefl, T., Overview of Nd-Fe-B magnets and coercivity,J. Appl. Phys., 1996, 79: 5029.

    Article  Google Scholar 

Download references

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Authors and Affiliations

  1. Department of Physics, Shandong University, 250100, Jinan, China

    Gao Ruwei, Zhang Jiancheng & Wu Liangxue

  2. Central Iron & Steel Research Institute, 100080, Beijing, China

    Li Wei & Yu Xiaojun

Authors
  1. Gao Ruwei
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  2. Li Wei
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  3. Zhang Jiancheng
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  4. Wu Liangxue
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  5. Yu Xiaojun
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Project supported by the National Natural Science Foundation of China (Grant No. 59571017).

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Ruwei, G., Wei, L., Jiancheng, Z. et al. Effects of orientation and interaction of grains on coercivity for sintered NdFeB magnets. Sci. China Ser. A-Math. 42, 653–659 (1999). https://doi.org/10.1007/BF02880084

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  • DOI: https://doi.org/10.1007/BF02880084

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