The effect of hydrogen pressure on the kinetics of the HDDR-process of bulk Nd-Fe-B-type alloys

Journal Article · Tue Mar 01 04:00:00 EST 1994 · IEEE Transactions on Magnetics

DOI:https://doi.org/10.1109/20.312362· OSTI ID:37267

Gutfleisch, O; Short, C; Verdier, M; Harris, I R ^[1]

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1. Univ. of Birmingham (United Kingdom). School of Metallurgy and Materials Science

The HDDR (hydrogenation, disproportionation, desorption, recombination)-process ob bulk Nd-Fe-B-type alloys has been investigated by in-situ electrical resistivity measurements. The effect of hydrogen pressure on the rate of the disproportionation reaction, in which the Nd{sub 2}Fe{sub 14}B phase forms Fe, Nd-hydride and Fe{sub 2}B, was studied in detail on a Nd{sub 14.68}Dy{sub 0.94}Al{sub 0.62}Fe{sub 76.47}Nb{sub 0.5}B{sub 6.79} alloy, which is used for the production of commercial permanent magnets. Experimental data reveal a strong dependence of the HDDR-kinetics on the hydrogen pressure which was varied between p(H{sub 2}) = 0.1--1.0 bar at T = 750 C. Optical micrographs suggest that the Nd-rich grain boundary phase acts as a diffusion path for the hydrogen in the HDDR-process. The 2-14-1 matrix phase subsequently disproportionates from the grain boundary phase inwards.

• OSTI ID: 37267
• Report Number(s): CONF-930860--
• Journal Information: IEEE Transactions on Magnetics, Journal Name: IEEE Transactions on Magnetics Journal Issue: 2Pt2 Vol. 30; ISSN IEMGAQ; ISSN 0018-9464
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ADDITIONS
BORON ALLOYS
DYSPROSIUM ALLOYS
EXPERIMENTAL DATA
FABRICATION
IRON BASE ALLOYS
MICROSTRUCTURE
NEODYMIUM ALLOYS
NIOBIUM ADDITIONS
PHASE STUDIES