Analysis of deformation mechanisms in superplastic yttria-stabilized tetragonal zirconia

Owen, David M and Chokshi, Atul H (2001) Analysis of deformation mechanisms in superplastic yttria-stabilized tetragonal zirconia. In: International Journal of Plasticity, 17 (3). pp. 353-368.

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Abstract

There have been extensive experimental observations of changes in the apparent rate controlling creep parameters in studies on superplastic materials. The three most common explanations associated with these changes in the stress exponent, n, the activation energy Q and the inverse grain size exponent, p involve the effect of concurrent grain growth, the operation of a threshold stress or transitions in creep mechanisms. Each of these factors may influence experimental creep data in a similar manner. Therefore, a careful analysis of the consequences of all three factors must involve the development of a consistent set of experimental observations in order to adequately distinguish the effects of each. This paper discusses the role of concurrent grain growth, a threshold stress and transitions in creep mechanisms in superplastic materials. Specific attention is given to the analysis of data on superplastic yttria-stabilized zirconia ceramics for which an increase in n has been observed at low applied stresses. It is demonstrated that neither concurrent grain growth nor a threshold stress can account for all the relevant experimental observations in this material. It is concluded that the changes in rate controlling creep parameters are associated with the operation of two distinct sequential mechanisms as part of a grain boundary sliding process.

Item Type:	Journal Article
Publication:	International Journal of Plasticity
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	Superplasticity;Deformation mechanisms.
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	02 Aug 2011 09:00
Last Modified:	02 Aug 2011 09:00
URI:	http://eprints.iisc.ac.in/id/eprint/39484

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