Uniaxial plastic deformation in the zirconia-based nanocrystalline ceramics containing a silicate glass

Nanocrystalline yttria-stabilized tetragonal zirconia polycrystal (nc-Y-TZP) powders coated with silicate based glasses were cold isostatically pressed and sintered near to the full density (98–99%). Two glasses with different compositions were used: 93 SiO2–1 Na2O–6 SrO (mol%) (designated as SNS glass) and 58 SiO2–29 Al2O3–13 SrO (designated as SAS glass). Uniaxial compression tests of the pure (glass-free) nc-Y-TZP samples yielded strain rates as high as 2·10−4 s−1 under 60 MPa at 1300 °C. Comparable strain rates were measured in the SNS glass-containing samples, with the maximum of 3·10−4 s−1 at 1300 °C under a stress of 80 MPa (5 vol.% SNS glass content). Compression tests under 100 MPa exhibited relatively high strain rates of 5·10−4 and 10−4 at 1300 °C and 1200 °C, respectively, in the 15 vol.% SAS glass samples. The strain rates measured in the SAS glass-containing samples were achieved at temperatures lower by 100 °C compared to the similar strain rates in the glass-free and SNS glass-containing samples. The microstructure of the deformed samples was similar to that of samples before deformation, within which the ultrafine and equiaxed character of the grains was preserved. Clear evidence for cooperative grain boundary sliding was observed in the SAS glass-containing samples.