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Bimodal Microstructure and Mechanical Properties of Cryomilled Nanocrystalline Al-7.5Mg

Published online by Cambridge University Press:  11 February 2011

Zonghoon Lee
Affiliation:
Department of Materials Science, University of Southern California, Los Angeles, CA 90089–0241, U.S.A.
David B. Witkin
Affiliation:
Department of Chemical Engineering and Materials Science, University of California at Irvine, Irvine, CA 92697–2575, U.S.A.
Enrique J. Lavernia
Affiliation:
Department of Chemical Engineering and Materials Science, University of California at Davis, Davis, CA 95616, U.S.A.
Steven R. Nutt
Affiliation:
Department of Materials Science, University of Southern California, Los Angeles, CA 90089–0241, U.S.A.
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Abstract

The microstructure and mechanical properties consisting of tensile behavior and hardness of bulk nanocrystalline Al-7.5Mg alloy were investigated. Grain refinement was achieved by cryomilling of atomized Al-7.5Mg powders, and then nanocrystalline powders blended with 15% and 30% coarse-grained Al-7.5Mg powders were consolidated by hot isostatic pressing (HIP) followed by extrusion to produce bulk nanocrystalline Al-7.5Mg alloys. Bimodal structures, which enhance ductility and toughness of nanocrystalline metals, were produced that consisted of nanocrystalline grains and elongated coarse-grain bands. Examination of indentation revealed unusual deformation mechanisms and interactions between the coarse-grain bands and nanocrystalline regions. The ductile coarse-grain bands underwent extensive plastic deformation near indentation, while nanocrystalline regions exhibited limited deformation.

Type
Research Article
Copyright
Copyright © Materials Research Society 2003

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References

REFERENCES

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