Superplastic Behavior in GeO<SUB>2</SUB> Doped Y-TZP

Abstract

The superplastic behavior in GeO2 doped 2.5Y-TZP was examined, especially, in terms of flow stress and tensile ductility by using high temperature tensile tests, X-ray diffraction analysis and scanning electron spectroscopy. ZrO2-2.5 mol%Y2O3-1.0 mol%GeO2 (TZP-1Ge) exhibits lower flow stress and larger tensile elongation than ZrO2-2.5 mol%Y2O3 (2.5Y-TZP) in a temperature range of 1200 and 1550°C at an initial strain rate of 1.3×10−4 s−1. The decrease in flow stress mainly results from enhanced diffusivity with a reduction in superplastic activation energy due to GeO2 addition. The improvement in tensile ductility in TZP-1Ge can also be explained by the enhanced diffusivity. Furthermore, the previous model proposed by Kondo et al. was applied to explain the tensile ductility in TZP-1Ge, however, it could not explain the tensile ductility in TZP-1Ge. It would indicate that the further consideration for the equation is required when applied to the superplastic behavior of TZP-1Ge.