HIGH-RESOLUTION ELECTRON-MICROSCOPY OF SILICON CARBIDE-WHISKER-REINFORCED ALUMINA COMPOSITE INTERFACES IN SPECIMENS SUBJECTED TO ELEVATED-TEMPERATURES

Interfaces of silicon carbide-whisker-reinforced alumina (SiC(w)/Al2O3 ) composites were examined using high-resolution electron microscopy ( HREM). HREM specimens were prepared from the bulk of samples that were previously tested for fracture toughness at 25-degrees, 1000-degrees, 1200-degrees, or 1400-degrees-C, in ambient air. The test temperature history served as an independent variable. It was found that the as-r eceived material did not possess a distinct interfacial layer and that the test temperature history (which included a 30-degrees-C/min heati ng and cooling rate, a 30-min soak prior to specimen loading, and a ty pical test duration of 5-10 min) did not appreciably change the interf ace thickness at any of the elevated test temperatures.