Characterization of Microstructure and Mechanical Properties of In-situ Toughened Si_3N_4

The microstructure and mechanical properties of in-situ toughened Si3N4 were studied by principal components analysis. The microstructure can be characterized by the first principal component of its characterization variables, which intitules complex microstructure index. Com- pact matrix with fine grains and uniform large grains with great aspect ration must be ensured in order to get in-situ toughened Si3N4 with excellent microstructure. It has been approved that materials with similar complex microstructure index possessing similar mechanical properties. The mechanical properties can be characterized by the first and the second principal components of its characterization variables, which intitule mechanical properties stability index and average me- chanical properties index. The former one reflects fracture toughness and Weibull modulus which are affected by the fluctuation of microstructure; the later one reflects the average mechanical property, namely strength.