Superplastic Properties of Zirconia-Hafnia Composites Doped with Various Oxides

The inuence of 1 mol% dopant of various oxides on the superplasticow of yttria stabilized tetragonal zirconia ceramics and zirconia - 10 mol% hafnia composite was examined in the temperature range 1553-1773 K. It was claimed that doping caused the increase of superplastic strain rate in zirconia and in zirconia-hafnia composite in comparison with undoped materials. The maximum strain rate for zirconia was measured for GeO2 addition; it was 16x higher than in pure ceramics, but for zirconia-hafnia the maximum strain rate was for SiO2 dopant (4x higher than in pure composite). There is a linear relationship between the grain boundary diffusion coefcient of Zr 4+ and superplastic strain