Magnetism of ultrathin intergranular boundary regions in Nd-Fe-B permanent magnets

Y. Murakami, T. Tanigaki, T. T. Sasaki, Y. Takeno, H. S. Park, T. Matsuda, T. Ohkubo, K. Hono, D. Shindo

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

The magnetism of a thin grain-boundary (GB) phase that envelopes the Nd2Fe14B grains in optimally annealed Nd-Fe-B sintered magnets was investigated by electron holography. The phase shift measured from a thin-foil specimen containing a tilted amorphous GB phase (∼3 nm in width) was -0.34 rad, which is substantially smaller than that expected for the nonferromagnetic GB phase of -1.2 rad. Simulations of the phase shift with various magnetization values suggest that the magnetic flux density of the GB phase is ∼1.0 T. The observations imply significant exchange coupling between Nd2Fe14B grains, which can explain the avalanche propagation of magnetization reversal observed in sintered magnets.

Original languageEnglish
Pages (from-to)370-379
Number of pages10
JournalActa Materialia
Volume71
DOIs
Publication statusPublished - Jun 2014

Fingerprint

Magnetism
Permanent magnets
Grain boundaries
Phase shift
Magnets
Electron holography
Magnetization reversal
Exchange coupling
Magnetic flux
Metal foil
Magnetization

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

Cite this

Murakami, Y., Tanigaki, T., Sasaki, T. T., Takeno, Y., Park, H. S., Matsuda, T., ... Shindo, D. (2014). Magnetism of ultrathin intergranular boundary regions in Nd-Fe-B permanent magnets. Acta Materialia, 71, 370-379. https://doi.org/10.1016/j.actamat.2014.03.013

Magnetism of ultrathin intergranular boundary regions in Nd-Fe-B permanent magnets. / Murakami, Y.; Tanigaki, T.; Sasaki, T. T.; Takeno, Y.; Park, H. S.; Matsuda, T.; Ohkubo, T.; Hono, K.; Shindo, D.

In: Acta Materialia, Vol. 71, 06.2014, p. 370-379.

Research output: Contribution to journalArticle

Murakami, Y, Tanigaki, T, Sasaki, TT, Takeno, Y, Park, HS, Matsuda, T, Ohkubo, T, Hono, K & Shindo, D 2014, 'Magnetism of ultrathin intergranular boundary regions in Nd-Fe-B permanent magnets', Acta Materialia, vol. 71, pp. 370-379. https://doi.org/10.1016/j.actamat.2014.03.013
Murakami, Y. ; Tanigaki, T. ; Sasaki, T. T. ; Takeno, Y. ; Park, H. S. ; Matsuda, T. ; Ohkubo, T. ; Hono, K. ; Shindo, D. / Magnetism of ultrathin intergranular boundary regions in Nd-Fe-B permanent magnets. In: Acta Materialia. 2014 ; Vol. 71. pp. 370-379.
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