The compressive strength of partially stabilized zirconia with 4-8mol% yttria was investigated in a relatively wide range of temperature. In each yttria-added material, the amount of metastable tetragonal (T) phase decreased with increasing yttria content and this was accompanied by fracture strength decrease by decrement of the T phase. The strength also decreased with increasing test temperature in the experimental range, and the magnitude of the temperature dependence became less important with increasing yttria content. In the case of 4mol% yttria stabilized zirconia, the fracture strain increased with temperature up to 450°C, but beyond this temperature, it decreased with increasing temperature. However, in the case of 6 or 8mol% yttria added zirconia, the fracture strain decreased monotonically with temperature. The fracture mode in the compression test could be roughly classified into three categories in a simple map representing the relation between yttria content and test temperature. Although almost all of the stress-strain curves retained their linearity until fracture occured, a peculiar shape of the curve exhibiting yield point and subsequent plastic deformation was observed in 4mol% yttria stabilized zirconia tested at temperatures between 400°C and 500°C.
