HIGH-RESOLUTION ELECTRON-MICROSCOPY STUDY OF INTERFACIAL STRUCTURE INTIB2-TI0.9W0.1C-SIC IN-SITU COMPOSITE

The ultrafine structure of multiphase ceramics TiB2-Ti0.9W0.1-SiC form ed by the in-situ reactive hot-pressing process has been characterized using high-resolution electron microscopy (HREM) and analytical elect ron microscopy. The results reveal that TIB2 crystallized into plate-l ike shapes, containing TiC plate precipitates. Three different orienta tion relationships between TIC precipitates and the TiB2 matrix were d etermined and the formation mechanism was proposed. Crystalline interg ranular phase containing Fe, Si and Ti elements were formed at grain e dge intersections. Along the TiB2 plates, the intergrowth of 6H-SiC ba nds were often found. An orientation relationship between the 6H-SiC a nd TiB2, in which [<11(2)over bar 0>](TIB2)//[<11(2)over bar 0>](SiC) and (0001)(TiB2)//(0001)(SiC), was found and the atomic structures at the TiB2/6H-SiC interface have been investigated by HREM combined with image simulations of several proposed models. Comparison of simulated images and the experimentally observed image resulted into an optimal structure model with Ti-B-C-Si stacking sequence at the interface.