The HDDR behaviour of crystalline and amorphous rapidly quenched NdFeB

D. Book, I. R. Harris, Azwar Manaf, I. Ahmad, H. A. Davies

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

The disproportionation and recombination reactions in which Nd2Fe14B decomposes into αFe, Nd hydride and Fe2B in hydrogen and then reforms under vacuum, have been investigated in melt-spun ribbon with the compositions Nd13.1Fe82.4B4.5 and Nd18Fe76B6. TPA and DTA investigations have shown that hydrogen absorption and desorption are more rapid in the amorphous Nd13.1Fe82.4B4.5 ribbon cast at 30 m s-1 than in the fully crystalline ribbon of this composition, spun at 10 m s-1. Disproportionation was found to occur in two stages in 30 m s-1 ribbon, the first stage in the range 400-500 °C associated with the amorphous phase, and the second stage in the range 500-700 °C due to the presence of crystalline Nd2Fe14B phase. By selecting ribbons with the smallest thicknesses, it was possible to investigate totally amorphous material on a Faraday balance, and these studies showed that, in this material, the disproportionation reaction was very rapid, and finished at 500 °C. This is in agreement with the observations on the two-phase material. In addition, DTA desorption measurements showed that recombination was more rapid and took place at a lower temperature in 30 m s-1 ribbon disproportionated at 500 °C compared with that disproportionated at 800 °C, suggesting a coarsening of the disproportionated microstructure at the higher temperature.

Original languageEnglish
Pages (from-to)180-186
Number of pages7
JournalJournal of Alloys and Compounds
Volume221
Issue number1-2
DOIs
Publication statusPublished - 15 Apr 1995

Keywords

  • Amorphous
  • Disproportionation
  • HDDR
  • Hydrogen
  • NdFeB

Fingerprint Dive into the research topics of 'The HDDR behaviour of crystalline and amorphous rapidly quenched NdFeB'. Together they form a unique fingerprint.

Cite this