Creep behavior in SiC-whisker reinforced silicon nitride composite

Tensile and flexural creep tests of 20 vol % SiC whiskers reinforced Si3N4 composite processed by gas pressure sintering have been carried out in air in the temperature range of 1000–1300°C. The stress exponent for flexural creep is 16 at 1000°C. However, at 1200 and 1250°C the stress exponents for both tensile and flexural creep vary with increasing stress. In the low stress region, the activation energy for creep is 1000 kJ/mol. In the high stress region, it is 680 kJ/mol. The different creep mechanisms dominate in the low and high stress regions, respectively.