A POSSIBLE FLOW MECHANISM OF ZIRCONIA IN ALUMINA-ZIRCONIA COMPOSITES SUPERPLASTICALLY DEFORMED IN COMPRESSION

The aim of this study is to investigate the possibility that zirconia particles deform plastically during superplastic compression of alumin a-zirconia composites. Various plastic deformation mechanisms of zirco nia (dislocation activity, lattice and grain boundary diffusion) are t aken into account in a self-consistent model which predicts the mechan ical behaviour of a composite when the viscoplastic laws of each phase are known. The predicted results are compared with the experimental d ata, i.e. the macroscopic rheology of the composites and the physical parameters related to the deformation of zirconia. From the comparison between the model and the experiments, a possible mechanism of plasti c deformation of zirconia is proposed. (C) 1997 Acta Metallurgica Inc.