COMPRESSIVE CREEP AND CREEP FAILURE OF 8Y(2)O(3) 3AL(2)O(3)-DOPED HOT-PRESSED SILICON-NITRIDE/

The compressive creep properties of hot-pressed Si3N4-8Y(2)O(3)-3Al(2) O(3) (wt%) have been investigated in the temperature range of 1543-160 3 K in air, The stress exponent, n, of the power creep law was determi ned to be 1.5, and the activation energy was determined to be 650 kJ/m ol. Transmission electron microscopy observations showed that grain-bo undary sliding occurred with cavitation formation in the grain-boundar y glassy phase. The quasi-steady-state creep results were consistent w ith that of the diffusion-controlled solution-diffusion-precipitation creep mechanism, and the distinguished failure mechanism was cavitatio n creep damage controlled by the viscosity of the boundary glassy phas e, The compressive creep failure time, obtained at 1573 K, in the stre ss range of 175-300 MPa, followed the Monkman-Grant relation, indicati ng that cavity growth was mainly controlled by the creep response of t he material.