Effect of Crystallizing the Grain‐Boundary Glass Phase on the High‐Temperature Strength of Hot‐Pressed Si 3 N 4 Containing Y 2 O 3

The effects of fabrication variables on the high‐temperature strength of hot‐pressed Si 3 N 4 containing 5 wt% Y 2 O 3 were studied. Materials containing a crystalline grain‐boundary phase, formed as a consequence of a high‐temperature presintering heat treatment and identified as Si 3 N 4 ·Y 2 O 3 , had high‐temperature strengths significantly superior to those observed for materials containing a glass phase.