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Analytical TEM study of Al-doped, “two-phase” Nd–Fe–B sintered magnets

Published online by Cambridge University Press:  31 January 2011

J. Fidler ,
K. G. Knoch ,
H. Kronmüller  and
G. Schneider
J. Fidler
Affiliation:
Institut für Angewandte Physik, T.U. Wien, Wiedner Hauptstr. 8-10, A-1040 Wien. Austria
K. G. Knoch
Affiliation:
Max-Planck-Institut für Metallforschung, Heisenbergstr.1. D-7000 Stuttgart 80, Federal Republic of Germany
H. Kronmüller
Affiliation:
Max-Planck-Institut für Metallforschung, Heisenbergstr.1. D-7000 Stuttgart 80, Federal Republic of Germany
G. Schneider
Affiliation:
Max-Planck-Institut für Metallforschung, Heisenbergstr.1. D-7000 Stuttgart 80, Federal Republic of Germany
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Abstract

The microstructure and the coercivity of sintered Nd20Fe(73.5-x)B6.5Alx (x = 0, 2.5) permanent magnets are influenced by the Al concentration. In Al-containing magnets we found a homogeneous distribution of Al in the hard magnetic phase and the occurrence of an intergranular Nd(Fe, Al)2, phase between the hard magnetic grains. Our analytical TEM study revealed that in “Al2O3-doped” magnets the crystal structure of the Nd-rich intergranular phase partly changes from fcc (a = 0.52 nm) to hep (a = 0.39 nm, c = 0.61 nm), whereas the content of iron simultaneously decreases from 5–10 at.% to 1.5–4 at.%. A platelet-shaped phase, embedded in the Nd-rich intergranular phase, was determined as a Nd5Fe2 (B, O)x, phase. The influence of the microstructure on the coercivity in Al-doped magnets is discussed.

Type
Articles
Information
Journal of Materials Research , Volume 4 , Issue 4 , August 1989 , pp. 806 - 814
Copyright
Copyright © Materials Research Society 1989

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References

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