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Superplastic Flow in Ceramic Microfiber Specimens

Published online by Cambridge University Press:  22 February 2011

R. Lappalainen  and
R. Raj
R. Lappalainen
Affiliation:
Cornell University, Dept. of Materials Science and Engineering, Bard Hall, Ithaca, NY 14853–1501, U.S.A.
R. Raj
Affiliation:
Cornell University, Dept. of Materials Science and Engineering, Bard Hall, Ithaca, NY 14853–1501, U.S.A.
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Abstract

Tensile superplastic deformation was studied using ceramic specimens that had a cross section of approximately 1 μm × 10–50 μm, and a length of 4 mm. These fibers were prepared by physical vapor deposition of oxides on a predefined pattern made by lithography.

Experiments with Y2O3 stabilized ZrO2 fibers and spinel fibers showed two characteristic features of flow behavior: serrations and a threshold stress. The serrations were explained by a flow model based on discrete sliding events distributed in time and space throughout the polycrystal. These fluctuations in flow stress were detected in our microfiber specimens due to relatively few grains in the gage section. Experimental results of the effect of sample size, grain size and strain rate on the serration behavior are discussed in the frame of the new model.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 239: Symposium D – Thin Films: Stresses and Mechanical Properties III , 1991 , 133
Copyright
Copyright © Materials Research Society 1992

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References

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