HIGH-TEMPERATURE SUPERPLASTIC CREEP AND INTERNAL-FRICTION OF YTTRIA-DOPED ZIRCONIA POLYCRYSTALS

Creep tests in compression and internal friction experiments have been performed in order to investigate the influences of microstructural parameters such as the grain size and the amount of intergranular glassy phase on the plastic deformation of yttria stabilized tetragonal zirconia polycrystals. The values of the apparent activation energies obtained from creep tests in the low stress regime and those obtained from the internal friction tests are in good agreement. The two techniques appear to be complementary approaches to the study of plastic deformation of fine grained zirconia under low stress. The mechanisms of plastic deformation are discussed in terms of grain boundary sliding models.