Application of Electron Microscopy for the Analysis of the Mechanical Behavior of Advanced Ceramics

The microstructure and fracture surfaces of two commercially available silicon nitride ceramics have been characterized using techniques of scanning and analytical transmission electron microscopy. These results have been correlated to mechanical property data (obtained from static and dynamic fatigue tests using four-point flexural test methods both at room temperature and at elevated temperature). For one of the materials, the results clarified failure mechanisms. For the other, the results showed how processing variables can affect microstructure (and thus mechanical behavior), and emphasized particularly that mechanical tests of billet-derived specimens may be unreliable in predicting the mechanical behavior of production components.