Microstructure of 96% Alumina Ceramics: II, Crystallization of High‐Magnesia Boundary Glasses

Abstract
Development of the grain‐boundary microstructure with heat treatment at 800° to 1500°C was examined for a group of 96% Al2O3 ceramics containing a high‐MgO boundary phase. Using a combination of analytical and conventional electron microscopy techniques, eight different crystalline phases were detected at the boundaries following annealing. Despite the extensive devitrification, however, a residual glass remained in all samples examined, and is believed to be continuous.