Microstructure and composition in rapidly quenched NdFeB-based hard magnet alloys

Journal Article · Mon Apr 01 04:00:00 EST 1996 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.361630· OSTI ID:280017

Nguyen, T D; Krishnan, K M ^[1]; Lewis, L H; Zhu, Y; Welch, D O ^[2]

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1. National Center for Electron Microscopy, Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 (United States)
2. Department of Applied Science, Brookhaven National Laboratory, Upton, New York 11973 (United States)

A detailed study of the microstructure and composition in hot-pressed (MQ-2) and die-upset (MQ-3) magnet alloys based on the Nd{sub 2}Fe{sub 14}B composition, utilizing high resolution and analytical transmission electron microscopy, is reported. The initial magnetic properties of the two samples show different behaviors, which are attributed to the difference in the anisotropy of the grain structure and the grain boundaries. The hot-pressed sample shows faceted grains of the 2-14-1 phase, while die-upset sample shows plate-like grains, together with larger equiaxed grains that contain a speckling of precipitates in the grain interior. The grain structure and composition remain rather similar in the two samples. The grain boundary phase averages {approximately}1{endash}{approx_gt}10 nm in width. The thicker grain boundaries are Nd-rich, while the thinner grain boundaries in the hot-pressed sample exhibit an Fe-rich composition near that of the NdFe{sub 3} phase. Nd-rich phases are found at the grain boundary junctions of both samples, with the Nd:Fe ratio near 7:3 in the die-upset sample, and up to 3:2 in the hot-pressed sample. The significance of the microstructure and the grain boundary phases on the magnetic behavior in the two samples is discussed. {copyright} {ital 1996 American Institute of Physics.}

• OSTI ID: 280017
• Report Number(s): CONF-951101--
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 8 Vol. 79; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHEMICAL COMPOSITION
HOT PRESSING
IRON BORIDES
MAGNETIC MATERIALS
MAGNETIC PROPERTIES
MELT SPINNING
MICROSTRUCTURE
NEODYMIUM BORIDES
PHASE STUDIES
TEMPERATURE RANGE 1000-4000 K
THERMOMECHANICAL TREATMENTS