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Magnetization reversal in melt-quenched NdFeB

By D.C. Crew


Melt-quenched NdFeB is an important modern permanent magnet material. However, there still remains doubt as to the magnetization reversal mechanism which controls coercivity in material prepared by this processing route. To investigate this problem a new technique based on measurements of reversible magnetization along recoil curves has been used. The technique identifies the presence of free domain walls during magnetic reversal. For this study samples of isotropic (MQI), hot pressed (MQII) and die upset (MQIII) melt-quenched NdFeB were examined. The results indicate that in MQI free domain walls are not present during reversal and the reversal mechanism is most likely incoherent rotation of some form. Free domain walls are also not present during reversal in the majority of grains of MQII, even though initial magnetization measurements indicate that the grain size is large enough to support them. In MQIII free domain walls are present during reversal. These results are attributed to the reduced domain wall nucleation field in MQIII compared with MQII and the increased dipolar interactions in MQIII

Topics: Magnetization, 36 Materials Science, Neodymium Alloys, Domain Structure, Permanent Magnets, Magnetic Materials, Fabrication, Coercive Force, Iron Alloys, Boron Alloys
Publisher: Brookhaven National Laboratory
Year: 1999
DOI identifier: 10.2172/350917
OAI identifier:
Provided by: UNT Digital Library
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