Superplasticity in cubic yttria-stabilized zirconia with intergranular silica Original Research Article

The effect of amorphous silicate additions on grain growth and high-temperature deformation of 8 mol% cubic yttria stabilized zirconia was investigated. Fine-grained (0.5 μm) samples were produced by addition of 5 wt% colloidal silica. Dynamic grain growth was limited by the presence of this inert intergranular amorphous phase with low solubility for zirconia and yttria. Strain rates as high as 5×10−3 s−1 at 1500 °C were observed under compression, similar to those observed in superplastic tetragonal yttria stabilized zirconia. Over 180% true strain (505% engineering strain) could be obtained within 1 h at 1500 °C. The stress exponent for deformation was calculated to vary from 1.3–1.7 at temperatures of 1300–1500 °C, respectively. Activation energies for superplastic deformation in the range of 340–410 kJ/mol were obtained for applied stresses of 10–45 MPa.