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High Rate Superplastic Deformation Mechanisms in IN90211 Mechanically Alloyed Aluminum

Published online by Cambridge University Press:  16 February 2011

Thomas R. Bieler  and
Amiya K. Mukherjee
Thomas R. Bieler
Affiliation:
Department of Metallurgy, Mechanics, and Materials Science, Michigan State University, East Lansing, MI 48824
Amiya K. Mukherjee
Affiliation:
University of California at Davis, Department of Mechanical Engineering, Division of Materials Science, Davis, CA 95616
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Abstract

IN90211 has exhibited superplastic elongations above 500% at high homologous temperatures (0.76–0.82 Tm). A high strain rate and flow stress for optimum elongation was measured (1–5/sec, 20–60 MPa, 425–485 °C). The apparent strain rate sensitivity of m≈0.25 differs from the usual m≈0.5 observations of superplastic deformation. An analysis of the data at several strains indicates a highly temperature dependent threshold stress is present, with either a n=2 or n=3 assumption for the stress exponent. The magnitude of the threshold stresses in IN90211 are smaller than usually observed in a dispersion strengthened matrix (1–20% instead of ≈50% of the Orowan stress). Experimental evidence from creep experiments supports the n=3 deformation mechanism as the rate limiting step of deformation.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 196: Symposium T – Superplasticity in Metals, Ceramics, and Intermetallics , 1990 , 259
Copyright
Copyright © Materials Research Society 1990

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References

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