Creep of an Al2O3-SiC(whisker)-TiC(particle) composite

Compressive creep of an electrodischarge-machinable composite, Al2O3/30.9 vol.%. SiC-whiskers/23 vol.% TiC-particles, was studied at 1350-1458 °C in inert atmospheres. The microstructure of the deformed specimens was analyzed by scanning and transmission electron microscopy. At stresses below 80 MPa, partially unaccommodated grain-boundary sliding was the rate-controlling mechanism for creep, with a stress exponent of approximately 1 and an activation energy of approximately 470 kJ mol-1. Damage accumulated at stresses above 80 MPa as a consequence of the insufficient diffusional transport of matter. This damage was responsible for an increased stress exponent.