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Microstructural Studies of High Coercivity Nd15Fe77B8 Sintered Magnets

Published online by Cambridge University Press:  25 February 2011

M. H. Ghandehari  and
J. Fidler
M. H. Ghandehari
Affiliation:
Unocal Corporation, Science and Technology Division, P.O. Box 76, Brea, CA 92621, USA
J. Fidler
Affiliation:
Institute of Aapplied and Technical Physics, Technical University of Vienna, Vienna, Austria
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Abstract

Microstructures of Nd15−xDyxFe77B8 prepared by alloying with Dy, and by using Dy2O3 as a sinl'ken adidive, have been determined using electron microprobe and transmission electron microscopy. The results have shown a higher Dy concentration near the grain boundaries of the 2–14–1 phase for magnets doped with Dy2O 3, as compared to the Dy-alloyed magnets. A two-step post sintering heat treatment was also studied for the two systems. The resultant concentration gradient of Dy in the 2–14–1 phase of the oxide-doped magnets is explained by the reaction of Dy2O3 with the Nd-rich grain boundary phase and its slow diffusion into thg 4–14–1 phase. Increased Dy concentration near the grain boundary is more effective in improving the coercivity, as domain reversal nucleation originates at or near this region.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 96: Symposium F – High Performance Permanent Magnet Materials , 1987 , 193
Copyright
Copyright © Materials Research Society 1987

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References

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