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Magnetization Reversal In Melt-Ouenched NdFeB

Published online by Cambridge University Press:  21 February 2011

D.C. Crew ,
L.H. Lewis ,
P.G. Mccormick ,
R. Street  and
V. Panchanathan
D.C. Crew
Affiliation:
Materials Science Division, Bldg 480, Department of Applied Science, Brookhaven National Laboratory, Upton, NY, U.S.A.11973-5000, dcrew@bnl.gov
L.H. Lewis
Affiliation:
Materials Science Division, Bldg 480, Department of Applied Science, Brookhaven National Laboratory, Upton, NY, U.S.A11973-5000
P.G. Mccormick
Affiliation:
Special Research Center for Advanced Mineral and Materials Processing, The University of Western Australia, Nedlands, WA, Australia 6907
R. Street
Affiliation:
Special Research Center for Advanced Mineral and Materials Processing, The University of Western Australia, Nedlands, WA, Australia 6907
V. Panchanathan
Affiliation:
Magnequench International, Inc., Anderson, Indiana, U.S.A
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Abstract

Melt-quenched NdFeB is an important modem 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 MQII compared with MQII and the increased dipolar interactions in MQIII.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 577: Symposium H – Advanced Hard and Soft Magnetic Materials , 1999 , 321
Copyright
Copyright © Materials Research Society 1999

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References

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