Nanocriletalline-matrix ceramic composites for improved fracture toughness

This article focuses on nanocrystalline-matrix ceramic composites specifically designed for-applications requiring improved fracture toughness. While the models and theory of toughening mechanisms for microcrystalline composites are well developed, the same cannot be said, for their-nanocrystalline counterparts. The difficulty in producing fully consolidated ceramic composites that retain a nanocrystalline structure is the main hurdle to thorough investigations in this area. Thus, much of the research on so-called nanocomposites has been on materials with microcrystalline matrices and nanometric second phases. In this article, we present the general principles of toughness mechanisms in microcrystalline ceramic composites, and then extend these ideas to consider how they should apply to ceramics with nanocrystalline matrices. While-work in this area is still quite limited we review current research focused,on the production and testing of composites with nanocrystalline matrices and second phases, and we recap the results of some promising fracture toughness reports.