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Strengthening of Aluminum by Oxygen Implantation: Experimental Results and Mechanical Modeling

Published online by Cambridge University Press:  25 February 2011

Roy J. Bourcier
Affiliation:
Sandia National Laboratories, Albuquerque, NM 87185, U.S.A.
David M. Follstaedt
Affiliation:
Sandia National Laboratories, Albuquerque, NM 87185, U.S.A.
Samuel M. Myers
Affiliation:
Sandia National Laboratories, Albuquerque, NM 87185, U.S.A.
Douglas H. Polonis
Affiliation:
University of Washington, Seattle, WA 98195, U.S.A.
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Abstract

The microstructuTe and mechanical properties of high purity aluminum implanted with 20 at.% oxygen to a depth of roughly 500 nm and subjected to various thermal histories have been examined. Transmission electron microscopy and Rutherford-backscattering spectrometry were used to characterize the depth and nature of the implanted zone. As implanted, the material appears to contain a homogeneous distribution of disordered precipitates with sizes of 1.5-3.5 nm. Annealing at 450 or 550ΰC for 1 hour, induces ordering of the precipitates but only causes slight coarsening. Ultra-low load indentation hardness testing was used to probe the mechanical response of the surface-modified material. The data from the hardness tests were interpreted through the use of a finite-element model; the results indicate the flow stresses of an implanted and annealed layer are as high as 1600 MPa. The as-implanted material is much harder, approaching 3300 MPa. The degree of strengthening expected for the as-implanted and post-annealed material on the basis of the observed microstructure was estimated using several micromechanical models, and the results conform to the findings from indentation testing.

Type
Research Article
Copyright
Copyright © Materials Research Society 1990

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References

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