Nanocomposite Nd-rich Nd-Fe-B alloys: Approaching ideal Stoner-Wohlfarth type behavior

Journal Article · Mon Mar 27 04:00:00 EST 2000 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.126154· OSTI ID:20215696

Girt, Er ^[1]; Krishnan, Kannan M ^[2]; Thomas, G ^[3]; Altounian, Z ^[4]

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1. Material Science Division, Lawrence Berkeley National Laboratory and Department of Material Science and Mineral Engineering, University of California, Berkeley, California 94720 (United States)
2. Material Science Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)
3. Material Science Division, Lawrence Berkeley National Laboratory, and Department of Material Science and Mineral Engineering, University of California, Berkeley, California 94720 (United States)
4. Department of Physics, Centre for the Physics of Materials, McGill University, Montreal, Quebec H3A 2T8, (Canada)

Starting from rapidly quenched Nd{sub {delta}}Fe{sub 13.1}B(2.05{<=}{delta}{<=}147.6) alloys and by appropriate annealing, the microstructure was tailored from strongly interacting Nd{sub 2}Fe{sub 14}B grains to magnetically isolated single domain Nd{sub 2}Fe{sub 14}B grains embedded in a nonmagnetic Nd-rich matrix ({alpha}-Nd and {gamma}-Nd). This change in microstructure was found to have a large effect on coercivity, i.e., coercivity, {mu}{sub 0}H{sub c}, increases with an increase of the Nd concentration from 1.25 T in Nd{sub 2.05}Fe{sub 13.1}B to 2.75 T in Nd{sub 147.6}Fe{sub 13.1}B at 290 K. Using transmission electron microscopy, the Nd{sub 2}Fe{sub 14}B grains in Nd{sub 147.6}Fe{sub 13.1}B were confirmed to be randomly oriented platelets with the c axis normal to the plate and an average size of 100x40x25 nm. For these randomly oriented, noninteracting, single domain Nd{sub 2}Fe{sub 14}B grains, the coercivity was calculated using a Stoner-Wohlfarth model which included the shape anisotropy of the grains. The observed coercivity of Nd{sub 2}Fe{sub 14}B in such nanocomposite Nd{sub 147.6}Fe{sub 13.1}B alloys is {approx}83% of its theoretical value. (c) 2000 American Institute of Physics.

• OSTI ID: 20215696
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 13 Vol. 76; ISSN APPLAB; ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BORON ALLOYS
COERCIVE FORCE
EXPERIMENTAL DATA
GRAIN SIZE
IRON ALLOYS
MICROSTRUCTURE
NEODYMIUM ALLOYS
PERMANENT MAGNETS
TRANSMISSION ELECTRON MICROSCOPY