Authors: S.S. Bhattacharya, U. Betz and H. Hahn
Affilation: IIT Madras, India
Pages: 292 - 295
Keywords: nanocrystalline ceramics, 5Y-PSZ, superplastic deformation, grain boundary sliding, activation energy
Superplastic deformation behaviour is now well established in fine-grained zirconia ceramics at fairly high temperatures (well above 0.5Tm, where Tm is the absolute melting point). In this study, an attempt was made to develop a nanocrystalline 5 mol.% yttria partially stabilised zirconia ceramic (5Y-PSZ) capable of exhibiting superplastic flow at relatively lower temperatures. A physical vapour processing route was used to synthesise the powders which was consolidated and subjected to a pressureless sintering route. Dense specimens with grain sizes in the nanometer range were subjected to tensile as well as compressive tests in the temperature range of 1283-1523K at different stress or strain rate levels in order to determine the superplastic deformation behaviour. The stress strain strain rate response of the material was analysed by a model for grain boundary sliding controlled superplastic flow. It was demonstrated that the strain rates predicted by the model are in close agreement with the experimentally observed ones.