An improved HDDR treatment for the production of anisotropic Nd-Fe-B ternary powders

S. Sugimoto, N. Koike, D. Book, T. Kagotani, M. Okada, K. Inomata, M. Homma

Research output: Contribution to journalConference articlepeer-review

39 Citations (Scopus)


The magnetic properties of Nd 12.2Fe 81.8B 6.0 alloys processed using a new HDDR (hydrogenation disproportionation desorption recombination) treatment were investigated. This newly proposed HDDR treatment is a combination of heat treatments at hydrogen pressures close to the recombination pressure of the Nd 2Fe 14B compound, in both the disproportionation and recombination stages. In other words, this new treatment is a combination of the l-HD (heating in a low H 2 pressure during the hydrogenation disproportionation stage), and s-DR (heating in Ar or in a relatively high pressure of hydrogen, at the start of recombination) treatments. In this investigation, the influence of the s-DR conditions on the magnetic properties of anisotropic Nd-Fe-B HDDR-treated powders, were investigated. It was found that an s-DR treatment in which the hydrogen pressure was decreased in steps from 0.1 MPa to 0.5 kPa, enhanced the remanence (1.45 T) and anisotropy (Br/Js=0.94). The rate at which the hydrogen pressure decreases to 6 kPa during s-DR is also considered to be an important factor in obtaining both a high remanence and a high coercivity. In addition, the coercivity was found to increase after an s-DR treatment in which the temperature was decreased in a step by step manner.

Original languageEnglish
Pages (from-to)892-896
Number of pages5
JournalJournal of Alloys and Compounds
Publication statusPublished - 2002 Jan 17
EventProceedings of the International Symposium on Metal-Hydrogen (MH 2000) - Noosa Heads, QLD, Australia
Duration: 2000 Oct 12000 Oct 6


  • Anisotropy
  • Disproportionation
  • HDDR
  • Hydrogen pressure
  • Nd-Fe-B
  • Recombination

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry


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