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TEM and XAS Characterization of Hard Magnetic Phase in Nd-Fe Alloys

Published online by Cambridge University Press:  01 February 2011

G. Kumar ,
J. Eckert ,
W. Löser ,
P. Schilling ,
E. Ma ,
C. Mickel  and
L. Schultz
G. Kumar
Affiliation:
IFW Dresden, Institute for Metallic Materials, D-01171 Dresden, Germany.
J. Eckert
Affiliation:
TU Darmstadt, Department of Materials and Earth Sciences, Physical Metallurgy Division, D-64287 Darmstadt, Germany.
W. Löser
Affiliation:
IFW Dresden, Institute for Metallic Materials, D-01171 Dresden, Germany.
P. Schilling
Affiliation:
Department of Mechanical Engineering, University of New Orleans, New Orleans, USA.
E. Ma
Affiliation:
Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, USA.
C. Mickel
Affiliation:
IFW Dresden, Institute for Metallic Materials, D-01171 Dresden, Germany.
L. Schultz
Affiliation:
IFW Dresden, Institute for Metallic Materials, D-01171 Dresden, Germany.
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Abstract

Nd80Fe20 alloys were prepared by copper mold casting and directional solidification (DS) to obtain a coarse microstructure, which can be identified unambigously. The mold-cast samples exhibit a fine globular eutectic structure and show high room temperature coercivity (∼ 5 kOe). Transmission electron microscopic (TEM) investigations reveal the presence of fcc (a = 5.32 Å) Nd-rich and nanocrystalline non-cubic Fe-rich phases. The directionally solidified (DS) samples exhibit large grains (composition close to NdFe2). The NdFe2 grains (formed in the DS samples) show clear magnetic domains with uniaxial anisotropy indicating that the NdFe2-type phase observed in the present samples is not a cubic phase. X-ray absorption spectroscopy (XAS) was used to analyze the local configuration around Fe atoms in the mold-cast samples. The XAS patterns do not match with the bcc and fcc standards, which supports the presence of NdFe2 phase with uniaxial symmetry in the DS samples.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 806: Symposium MM – Amorphous and Nanocrystalline Metals , 2003 , MM3.2
Copyright
Copyright © Materials Research Society 2004

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References

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