Critical assessment of high-temperature deformation and deformed microstructure in high-purity tetragonal zirconia containing 3 mol.% yttria

Abstract

Tensile creep has been investigated in a fine-grained yttria-stabilized tetragonal zirconia (3Y-TZP). The creep data corrected for grain growth reveal a high stress region with a stress exponent of n∼2.7 and a grain size exponent of p∼2.0–3.0, an intermediate stress region with n∼5.0, and a low stress region with n∼1.3 and p∼1.8. In the whole region, the apparent activation energy takes a value for the lattice diffusion of cations (580 kJ/mol). Microstructural observation reveals that intragranular dislocation motion is noticeably activated in the high stress region, limited in the intermediate stress region and absent in the low stress region. The results suggest that the rate of deformation is controlled by the recovery of the intragranular dislocations in the high stress region and by Nabarro–Herring creep in the low stress region. The intermediate stress region is related to a threshold stress for the dislocation motion.