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The Preparation of Mechanically Alloyed Powders for TEM Examination

Published online by Cambridge University Press:  21 February 2011

E. A. Kamenetzky
Affiliation:
Materials and Chemical Sciences Division, Lawrence Berkeley Laboratory, University of California, Berkeley, CA 94720.
M. Wall
Affiliation:
Chemistry and Materials Science Department, Lawrence Livermore National Laboratory, Livermore, CA 94550.
R Castro
Affiliation:
Chemistry and Materials Science Department, Lawrence Livermore National Laboratory, Livermore, CA 94550.
L. E. Tanner
Affiliation:
Chemistry and Materials Science Department, Lawrence Livermore National Laboratory, Livermore, CA 94550.
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Abstract

TEM specimens of mechanically alloyed elemental Ni and Nb powders are prepared by a new procedure. The alloyed powders are mixed with smaller Al powders and fill an aluminum ring (3mm outer diameter). This composite is cold pressed together with the Al powders taking most of the deformation. The compacted specimen can be mechanically thinned. Electropolishing and ion milling can then proceed by standard methods with special precautions to minimize differential polishing or milling rates.

The microstructural aspects of the formation of an amorphous phase by high-energy ball milling these powders have been studied. After 6 h each particle transforms to a heterogeneous layered composite of particles of one element in the matrix of the other. Particle size ranges from 15 nm to 90 nm. Mechanical alloying for 36 h results in the formation of an apparently uniform phase interspersed with a few small (4 nm to 30 nm) elemental crystalline particles. The uniformity of composition and the presence of C, O, and Fe were studied by EDX and EELS.

Type
Research Article
Copyright
Copyright © Materials Research Society 1988

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References

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