Hydrogenation disproportionation desorption and recombination (HDDR) studies on direct-reduced Nd{sub 15}Fe{sub 77{minus}x}B{sub 8}Ga{sub x} powders

Journal Article · Wed Nov 01 04:00:00 EST 1995 · IEEE Transactions on Magnetics

DOI:https://doi.org/10.1109/20.489591· OSTI ID:186929

Burkhardt, C; Harris, I R ^[1]; Steinhorst, M ^[2]

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1. Univ. of Birmingham (United Kingdom). School of Metallurgy and Materials
2. Elektro-Thermit GmbH, Essen (Germany)

Direct-reduced Nd-Fe-B powders with additions of 1.0% and 2.0% Ga were treated by the HDDR process at temperatures between 770 C and 900 C in order to optimize the processing parameters. The microstructures of the powders were investigated by scanning electron microscopy (SEM) on rotary forged Al bonded samples. The investigation of the magnetic properties was carried out on wax-bonded samples on a vibrating sample magnetometer (VSM). It was found that the direct-reduced Nd-Fe-B powders containing Ga additions show significantly increased intrinsic coercivities of up to 895 kA/m compared to those of the ternary alloy or those of powders with Zr additions. The remanence appears to be, for both Nd{sub 15}Fe{sub 76}B{sub 8}Ga{sub 1} and Nd{sub 15}Fe{sub 75}B{sub 8}Ga{sub 2}, relatively constant over a processing temperature range of {approximately}50 C with Nd{sub 15}Fe{sub 76}B{sub 8}Ga{sub 1} exhibiting higher values of up to 680 mT. The disproportionation time has a significant influence on the magnetic properties of the material, higher processing temperatures requiring shorter times in the disproportionated state, lower temperatures longer times. Under the conditions employed in these experiments, the HDDR treatment removes existing anisotropy in the as-received coarse grain material, thus leading to predominantly isotropic behavior.

• OSTI ID: 186929
• Report Number(s): CONF-950404--
• Journal Information: IEEE Transactions on Magnetics, Journal Name: IEEE Transactions on Magnetics Journal Issue: 6Pt2 Vol. 31; ISSN IEMGAQ; ISSN 0018-9464
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BORON ALLOYS
EXPERIMENTAL DATA
FABRICATION
GALLIUM ALLOYS
IRON ALLOYS
MAGNETIC PROPERTIES
MAGNETS
MICROSTRUCTURE
NEODYMIUM ALLOYS
REDUCTION