Influence of grain boundary β-spodumene glass on the superplastic flow in tetragonal zirconia polycrystal (TZP)

Superplastic flow in β-spodumene-glass-doped tetragonal zirconia polycrystal (TZP) is examined by means of tensile testing at temperatures between 1200 and 1500°C. The presence of grain boundary β-spodumene glass is very effective in reducing the flow stress and enhancing the superplastic flow. The stress concentration caused by grain boundary sliding must be easily accommodated, probably via enhanced matter transport in the grain boundary glass phase, and hence the superplastic flow is accelerated in spite of the stress reduction, the tensile ductility of glass-doped TZP is very limited and is less than that of undoped TZP. The limited ductility is found to be due to the brittleness of the interface between zirconia grains and the glass phase.