R‐curves for hot‐pressed 20 vol% ZrO2(2.5‐YPSZ and 8‐YPSZ) reinforced MoSi2composites were evaluated using the indentation/bend technique. Results indicated a modest increase in the material toughness for both composites. ExperimentalR‐curves were compared with theoretically predictedR‐curves to evaluate the critical transformation stress for the partially stabilized ZrO2composite. A high critical transformation stress value obtained was indicative of the inhibition of transformation toughening effects due to microstructural inhomogeneity in the partially stabilized ZrO2‐Mo