High temperature plastic deformation at very low stresses of fine-grained Y2O3-partially stabilized ZrO2

Plastic deformation at elevated temperatures (1300-1450 degrees C) of 3 and 4 mol% Y2O3-stabilized ZrO2 polycrystals with fine grain size (d < 1 mu m) has been studied at very low stresses (< 10 MPa). Extensive internal cavitation has been found for a few percent of strain, instead of the superplastic behavior exhibited by these materials at intermediate and high stresses, along with a change of the stress exponent. These features are explained on the basis of a gradual inhibition of the grain boundary sliding to accommodate the macroscopic strain when decreasing the stress, supporting the existence of a threshold stress for this mechanism.