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 JEMAA  Vol.1 No.4 , December 2009
Effect of Weak Magnetic Intergranular Phase on the Coercivity in the HDDR Nd-Fe-B Magnet
Abstract: Assuming that intergranular phase (IP) existing between adjacent grains is a weak magnetic phase, we study the effect of IP on the coercivity in the HDDR Nd-Fe-B magnet. The results indicate that the coercivity increases with the increasing IP’s thickness d, but decreases with increasing its anisotropy constant K1(0). When the structure defect thickness r0 =6nm, d=1nm and K1(0)=0.15K1 (K1 is the normal anisotropy constant in the inner part of a grain), our calculated coercivity is in agreement with available experimental data.
Cite this paper: nullM. LIU, G. HAN and R. GAO, "Effect of Weak Magnetic Intergranular Phase on the Coercivity in the HDDR Nd-Fe-B Magnet," Journal of Electromagnetic Analysis and Applications, Vol. 1 No. 4, 2009, pp. 249-253. doi: 10.4236/jemaa.2009.14038.
References

[1]   H. Nakamura, R. Suefuji, S. Sugimoto, M. Okada, and M. Homma, “Effects of HDDR treatment conditions on magnetic properties of Nd-Fe-B anisotropic powders,” Journal Applied Physics, Vol. 76, No. 10, pp. 6828–6830, November 1993.

[2]   M. Sagawa, S. Fujimura, H. Yamamoto, Y. Matsuura, and K. Hiraga, “Permanent magnet materials based on the rare earth-iron-boron tetragonal compounds,” IEEE Tran- sactions on Communications, Vol. 20, No. 1, pp. 1584– 1589, January 1984.

[3]   R. K. Mishra, “Microstructure of melt-spun Nd-Fe-B ma- gnequench magnetis,” Journal of Magnetism and Magnetic Materials, Vol. 54, No. 1, pp. 450–456, February 1986.

[4]   M. Liu, Y. Sun, G. B. Han, Wu. Y, and R. W. Gao, “Dependence of anisotropy and coercivity on microstructure in HDDR Nd-Fe-B magnet,” Journal of Alloys Compounds, Vol. 478, pp. 303–307, April 2009.

[5]   T. Takeshita and R. Nakayama, “Magnetic properties and microstructures of the NdFeB magnet powder produced by hydrogen treatment,” Proceedings of the 10th International Workshop on Rare-Earth Magnets and Their Applications, Kyoto, Japan, pp. 551, 1989.

[6]   T. Takeshita, K. Morimoto, “Anisotropic Nd-Fe-B bonded magnets made from HDDR powders,” Journal Applied Physics, Vol. 79, No. 8, pp. 5040–5044, April 1996.

[7]   R. W. Gao, J. C. Zhang, and D. H. Zhang, “Dependence of the magnetic properties on the alignment magnetic field for Nd-Fe-B bonded magnets made from anisotropic HDDR powders,” Journal of Magnetism and Magnetic Materials, Vol. 191, No. 1, pp. 97–100, January 1999.

[8]   R. Nakayama, T. Takeshita, and M. Itakura, “Microstructures and crystallographic orientation of crystalline grains in anisotropic Nd-Fe-Co-B-(Ga or Zr) magnet powders produced by the hydrogenation-decomposition-desorp- tion-recombination process,” Journal Applied Physics, vol. 76, No. 1, pp. 412–417, July 1994.

[9]   Q. G. Ji, B. X. Gu, J. R. Zhang, Z. J. Tian, Y. W. Du, “Effects of aging at room temperature on as-spun NdFe B/a-Fe nanocomposite magnets,” Journal of Magnetism and Magnetic Materials, Vol. 288, No. 2, pp. 84–91, January 2005.

[10]   J. Fidler and T. Schrefl, “Overview of Nd-Fe-B magnets and coercivity,” Journal Applied Physics, Vol. 79, No. 2, pp. 5029–5034, September 1996.

[11]   M. Yue, X. B. Liu, Y. F. Xiao, and J. X. Zhang, “Magnetization reversal mechanism of anisotropic HDDR Nd2Fe14B-based magnet powder,” Journal of Magnetism and Magnetic Materials, Vol. 269, No. 2, pp. 227–230, February 2004.

[12]   H. Kronmller, K. D. Durst, and M. Sagawa, “Analysis of the magnetic hardening mechanism in RE-Fe-B permanent magnets,” Journal of Magnetism and Magnetic Materials, Vol. 74, No.3, pp. 291–302, February 1988.

[13]   H. Kronmller, M. Fischer, and R. Seeger, “Micromagnetism and microstructure of hard magnetic materials,” Journal Physics D, Vol. 29, No. 2, pp. 2274–2283, January 1996.

[14]   M. Sagawa and S. Fujimura, “New material for permanent magnets on a base of Nd and Fe,” Journal Applied Physics, Vol. 55, No. 6, pp. 2083–2087, March 1984.

[15]   G. B. Han and R. W. Gao, “Effect of exchange-coupling interaction on the effective anisotropy in nanocrystalline Nd2Fe14B material,” Journal of Magnetism and Magnetic Materials, Vol. 281, No. 1, pp. 6–10, October 2004.

[16]   M. Gr?onefeld and H. Kronmller, “Calculation of strayfields near grain edges in permanent magnet material,” Journal of Magnetism and Magnetic Materials, Vol. 80, No. 2, pp. 223–228, August 1989.

 
 
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