QUANTITATIVE MICROSCOPY OF BETA-SI3N4 CERAMICS

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