MICROSTRUCTURAL ASPECTS OF SUPERPLASTIC DEFORMATION OF AL2O3 ZRO2 LAMINATE COMPOSITES/

Mechanical properties in superplastic conditions of Al2O3/ZrO2 laminat e composites were studied in compression. The as-received material con sists of an appropriate stacking of 140 mu m thick layers, containing 10 or 20 vol.% ZrO2 particles. It is shown that an increase in zirconi a content limits alumina grain growth and decreases the creep resistan ce of the corresponding layers. Possible causes of these variations in creep behaviour are proposed in relation to grain refinement effect a nd a specific rheology of the zirconia inclusions. The relative contri butions of plastic deformation and phase boundary sliding to the total deformation are also discussed, based on the compared variation with strain of two parameters related to the grain shape.