An Analysis of Creep Mechanisms in Superplastic Yttria-Stabilized Zirconia

摘要

Extensive experimental results are now available for the creep of yttria-stabilized tetragonal zirconia (Y-TZP). This paper considers the following creep mechanisms: (a) Grain boundary sliding at high stresses and interface-reaction controlled flow at low stresses, (b) Interface-controlled diffusion creep over the entire range of stresses, (c) Grain boundary sliding with a threshold stress and (d) Intragranular dislocation motion at high stresses and Nabarro-Herring diffusion creep at low stresses. It is shown that interface-controlled grain boundary diffusion creep provides a satisfactory explanation of the results. The limiting behavior at high and low stresses, as well as at fine and coarse grain sizes, is discussed using a Deformation Limit Diagram (DLD).