Grain size and temperature dependence of the threshold stress for superplastic deformation in yttria-stabilized zirconia polycrystals

The influence of the threshold stress on the value of the activation energy (Q) and stress exponent (n) measured during creep tests in fine-grained Y2O3-doped ZrO2 polycrystals has been investigated in the low-stress region at intermediate temperatures. A significant increase of the measured value of Q and n with decreasing stress has been observed, consistent with the existence of a threshold stress for superplastic deformation.