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Published May 2012 | public
Journal Article

On the dynamically stored energy of cold work in pure single crystal and polycrystalline copper

Abstract

The thermo-mechanical response of single crystal and polycrystalline high purity copper is systematically compared at low and high strain rates. The mechanical response of each type of material is very different in terms of strain hardening, although both are distinctly strain rate sensitive. A simplified interpretation of the Taylor–Quinney coefficient, in which the strain dependence is not considered, shows a clear (almost linear) increase of this factor with the strain rate, while the two types show distinct trends. This factor increases with the strain rate but remains markedly lower than the classical value of 0.9. The stored energy of cold work is found to be relatively independent of the strain rate, with the polycrystal storing more energy than the single crystal. A microstructural study (transmission electron microscopy) of representative specimens of each type at low and high strain rates reveals a basically similar microstructure, despite dissimilar values of energy storage. It is proposed that a higher level of storage of the energy of cold work by polycrystalline copper is due to the presence of grain boundaries in this group.

Additional Information

© 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Received 14 November 2011; received in revised form 13 March 2012; accepted 18 March 2012; Available online 30 April 2012. The research support provided by the Caltech Center for the Predictive Modeling and Simulation of High Energy Density Dynamic Response of Materials through US Department of Energy Contract DE-FC52-08NA28613 is gratefully acknowledged.

Additional details

Created:
August 22, 2023
Modified:
October 17, 2023