Bimaterial composites via colloidal rolling techniques: III, mechanical properties

The mechanical properties of layered Ce-TZP/Al2O3 composites with laminate and cellular morphologies have been investigated. The strength and toughnes s increase as the layer thickness decreases, and the amount of transformati on in the Ce-TZP layer increases discontinuously at the laminate/cellular t ransition. Very high strengths (1.1 GPa) and toughnesses (16 MPa.m(1/2)) ha ve been obtained in some cases. These results indicate that the progressive refinement of layer microstructure and the disruption of planar connectivi ty of phases are beneficial to the mechanical performance, because they pro vide more stress concentrators to trigger stress-assisted transformation fo r toughening functions. The composites of finer microstructure, with a laye r thickness of less than or equal to 20 mu m, have a homogeneous hardness o f 11.5 GPa, which is a considerable improvement over that of Ce-TZP alone.