超塑性TZPの静的粒成長と変形応力に及ぼす微量ドーパント効果

抄録

Static grain growth behavior in 1 mol% of GeO₂, TiO₂, MgO or BaO-doped ZrO₂-3 mol%Y₂O₃ (3Y-TZP) was examined at 1400°C with a special interest in dopant effect on superplastic flow stress in fine-grained 3Y-TZP. The static grain growth can be described as normal grain growth in single-phase ceramics, and the growth constant K is in the order of 10% flow stress for each material. The value of K in cation-doped TZP correlates closely to dopant cation ionic radius. Assuming that the activation energy for diffusivity of constituent ions can be given as a linear function of strain caused by the ionic size difference, the dependence of the growth constant and the flow stress on the ionic radius can be described as a function of the dopant cation ionic radius. The calculated activation energy for the diffusivity is in good agreement with the experimental data in cation-doped TZP. The small dopant effect on the flow stress can be given by the activation energy difference due to the dopant cation ionic size.