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Dynamic strain aging and serrated flow in MnO

Published online by Cambridge University Press:  03 March 2011

K. C. Goretta ,
J. L. Routbort  and
T. A. Bloom
K. C. Goretta
Affiliation:
Materials Science and Technology Division, Argonne National Laboratory, Argonne, Illinois 60439
J. L. Routbort
Affiliation:
Materials Science and Technology Division, Argonne National Laboratory, Argonne, Illinois 60439
T. A. Bloom
Affiliation:
Department of Metallurgical and Materials Engineering, Illinois Institute of Technology, Chicago, Illinois 60616
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Abstract

The effects of aging on the upper yield stress τup and serrated flow have been studied in MnO single crystals at 900 °C for oxygen partial pressures ρO2 of 10−11 and 10−7 Pa. Aging initially increases τup as a consequence of segregation of aliovalent impurities to dislocations for both ρO2 values. For long aging times and ρO2 = 10-11 Pa, serrated flow accompanied by solute softening is observed. The data fit predictions of a Portevin-Le Chatelier model for serrations, but with impurity atmospheres causing softening instead of hardening. This is believed to result from changes in local defect equilibria caused by segregation of impurities with valences greater than two to dislocations.

Type
Articles
Information
Journal of Materials Research , Volume 1 , Issue 1 , February 1986 , pp. 124 - 129
Copyright
Copyright © Materials Research Society 1986

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References

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