Balasubramanian, N. and Langdon, Terence G.
Flow processes in superplastic yttria-stabilized zirconia: a Deformation Limit Diagram.
Materials Science and Engineering: A, 409, (1-2), . (doi:10.1016/j.msea.2005.06.071).
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The possible rate-controlling mechanisms in the deformation of superplastic 3Y-TZP are considered. It is generally recognized that intragranular dislocations play only a limited role in the creep of this material at stresses below ~100 MPa when testing at temperatures in the range from 1573 to 1873 K. Therefore, a single rate-controlling mechanism is proposed which is consistent with experimental reports of a single activation energy. The proposed mechanism is based on Coble diffusion creep with a transition to interface-controlled diffusion creep at the lowest stress levels. It is shown that an equation derived on the basis of this mechanism provides a very good fit, to within an order of magnitude of the strain rate, for experimental data reported by different investigators. A Deformation Limit Diagram is introduced and constructed to provide a simple pictorial representation of the transitions occurring in the creep behavior at these low stresses.
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