Lawrence Berkeley National Laboratory

The development of a high-toughness SiC is described, based on the notion of in situ toughening through the growth of plate-like, elongated grains in the presence of Al, B and C sintering additives during hot pressing. Samples prepared with varied amounts of additives were characterized to identify roles of each additive. The fully controllable microstructure and phase composition allowed for development of optimized recipes in response to different mechanical requirements. Mechanical performance was further enhanced through prescribed post-annealing at elevated temperatures, at which grain boundary and lattice diffusions were activated, resulting in strengthened intergranular films and formation of nanoscale precipitates interior SiC grains.