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Bimodal Microstructures in Nanocrystalline Al and Al-Mg Alloy Powders Prepared by Cryogenic Ball Milling

Published online by Cambridge University Press:  15 March 2011

F. Zhou
Affiliation:
Department of Materials Science, University of Southern California, Los Angeles, CA 90089
Z. Lee
Affiliation:
Department of Materials Science, University of Southern California, Los Angeles, CA 90089
E. J. Lavernia
Affiliation:
Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616
S.R. Nutt
Affiliation:
Department of Materials Science, University of Southern California, Los Angeles, CA 90089
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Abstract

The microstructures of nanocrystalline Al and Al-7.6 at% Mg alloy powders processed by cryogenic ball milling (i.e., cryomilling) and subsequent thermal annealing were characterized using transmission electron microscopy. The as-milled samples primarily consisted of equiaxed grains with average sizes of ∼ 26 nm. The annealing treatments at elevated temperatures resulted in bimodal grain-size distributions, with sub-micrometer-sized grains embedded in a matrix of nanocrystalline (<50 nm) grains. The bimodal microstructures were formed during the processes of recovery and recrystallization.

Type
Research Article
Copyright
Copyright © Materials Research Society 2004

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