HIGH-RESOLUTION INTERFACE ANALYSIS OF SIC-WHISKER-REINFORCED SI3N4 AND AL2O3 CERAMIC MATRIX COMPOSITES

Whisker/matrix interfaces between β-SiC whiskers and β-Si3N4 or α-Al2O3 matrices in composites were examined by high-resolution electron microscopy (HREM), and electron energy loss (ELS) and energy dispersive X-ray (EDS) spectroscopies. Most whisker/matrix interfaces were crystalline, with whiskers directly bonded to matrix crystals. Some whisker/matrix interface regions contained amorphous thin films and these occurred more often in the Si3N4 composite, which contained sintering additives, than in the Al2O3 matrix composite, which did not. No evidence for light element segregation at crystalline whisker/matrix interfaces was detected by ELS or EDS at 5 nm spatial resolution. Impurities were concentrated in glassy regions in matrix grain boundaries, triple junctions, or at infrequent whisker/matrix interfaces containing amorphous films. © 1990 Chapman and Hall Ltd.