Quantitative Microscopy of β‐Si3N4 Ceramics

The three-dimensional grain size distribution in an experimental β-Si3N4 material has been determined using the hexagonal prism as a model of β-Si3N4 grain shape. Results from quantitative microscopy of polished and etched sections were compared with computer-generated two-dimensional stereological parameters of hexagonal prisms with different aspect ratios in order to determine an average grain shape (i.e., aspect ratio) in the microstructure. Section parameter distributions for the average grain shape were obtained from the computer simulations and used in a three-dimensional reconstruction of the microstructure. The results showed that this Si3N4 ceramic had the postulated fibrous microstructure and a broad grain size distribution.