High temperature deformation of ceramic particle composites

The particle composites Al 2O 3/(2 and 3Y)TZP and MgAl 2O 4/3Y-TZP were tested in bending at temperature of 1280 °C over strain rates from 3.4 × 10 −7 to 1 × 10 −4 s −1 and over stresses from 23 to 85 MPa. Strain rate of the composites decreased as a volume fraction of Al 2O 3 or MgAl 2O 4 increased. MgAl 2O 4/3Y-TZP composites deformed easier under the comparable conditions than alumina/zirconia composites. Four models of composite creep behaviour were compared to the experimental data. All the models were unsuitable for MgAl 2O 4/3Y-TZP, in turn an isostress, an isostrain and a constrained isostrain models provide the good predictions for creep rates for alumina/zirconia ceramics, but the rheological model appeared not good. The threshold stresses approach seems to be useful for describing superplastic flow of MgAl 2O 4/3Y-TZP composites.