High temperature mechanical properties of SIC whisker reinforced Al_{2O_{3 composites

High–temperature constant load and constant strain rate compressive tests have been performed on Al2O3 reinforced with different concentrations of SIC whiskers. The samples were obtained from three sources, but contained whiskers from the same source. The temperature range was from 1300 to 1500°C and experiments were conducted in air and argon. Strain rates varied from 3x10−8 to 5x10−5 s−1 with stresses between 3 and 500 MPa. Stress exponents were found to vary between 1 and 5 and depended on microstructure, whisker concentration and stress, indicating a change in the mechanism controlling plastic deformation. Change from diffusional creep to a damage accumulation mechanism was supported by TEM observations on samples as–received and deformed both in the n=l regime and in the n=5 regime. Degradation of Sic whiskers occurred when testing in air.