Coercivity Enhancement by the Grain Boundary Diffusion Process to Nd-Fe-B Sintered Magnets

K. Hirota, H. Nakamura, T. Minowa, M. Honshima

Research output: Contribution to journalArticlepeer-review

248 Citations (Scopus)


Changes in magnetic properties after applying grain boundary diffusion process to Nd-Fe-B sintered magnets with a thickness of several millimeters were investigated, and their microstructures were also observed. Coercivities of the magnets coated with heavy rare earths (HRE=Dy and Tb) oxide or fluoride powder and then heat-treated, were enhanced significantly without a considerable reduction in a remanence. During the heat treatment, HRE element diffused into the magnet through the grain boundary, and formed HRE-rich shells around the grain boundary of the Nd2Fe14B phase by substituting Nd. The coercivity increased by more than 400 kA/m with a thickness of up to 3 mm for the magnet processed with TbF3.

Original languageEnglish
Pages (from-to)2909-2911
Number of pages3
JournalIEEE Transactions on Magnetics
Issue number10
Publication statusPublished - 2006 Oct
Externally publishedYes


  • Coercive force
  • Dy2O3
  • DyF3
  • TbF3
  • diffusion
  • grain boundary
  • powder

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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