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Magnetic Properties of Polymer Bonded Exchange-Spring NdFeB Magnets

Published online by Cambridge University Press:  21 February 2011

B. Mokal ,
N.A. Smith ,
A.J. Williams  and
I.R. Harris
B. Mokal
Affiliation:
School of Metallurgy and Materials, The University of Birmingham, Birmingham B 15 2TT, U.K
N.A. Smith
Affiliation:
School of Metallurgy and Materials, The University of Birmingham, Birmingham B 15 2TT, U.K
A.J. Williams
Affiliation:
School of Metallurgy and Materials, The University of Birmingham, Birmingham B 15 2TT, U.K
I.R. Harris
Affiliation:
School of Metallurgy and Materials, The University of Birmingham, Birmingham B 15 2TT, U.K
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Abstract

The production of remanence enhanced powders, using a method of mechanical alloying of free iron to melt spun ribbon, has been studied. The final composition is Nd8. 1Fe77.1Co10.9B3.9 and both hard and soft materials possess an initial fine grain size; approximately 30nm for the Nd2Fe14B phase in the melt spun ribbon and 1µm for the α-Fe. The magnetic properties of resin bonded magnets fabricated using such material have been measured and found to exhibit exchangespring behaviour. The experiments performed in this work are described with respect to the volume fraction of the soft phase and subsequent annealing temperature of the as-milled material. Remanence enhancement has been observed and this can be attributed to the exchange interactions between the ferromagnetic soft and hard phases. For a 30% by volume addition of α-Fe, typical values of remanence were found to be ∼880mT with a coercivity of ∼250 kA/m. The reversible and irreversible components of the magnetisation have been determined, to demonstrate the exchange coupling and coercivity behaviours respectively.

Keywords

Permanent magnetsexchange coupling
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 577: Symposium H – Advanced Hard and Soft Magnetic Materials , 1999 , 221
Copyright
Copyright © Materials Research Society 1999

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References

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