Room temperature mechanical properties and high temperature oxidation behavior of MoSi2 matrix composite reinforced by adding La2O3 and Mo5Si3

MoSi2 matrix composites containing 0.8 wt.%La2O3 and different volume fractions of Mo5Si3 were synthesized by self-propagating high temperature synthesis. The room temperature mechanical properties and high temperature oxidation behavior at 1200 °C were studied. Results showed that La2O3 and Mo5Si3 caused the grain size to decrease of the MoSi2 matrix composite. The flexure strength and fracture toughness are improved compared with pure MoSi2. The strengthening mechanism of La2O3–Mo5Si3/MoSi2 is fine-grain strengthening, and its toughening mechanisms are fine-grain toughening, crack deflection, crack branching and crack bridging. With an increase in Mo5Si3 content, the oxidation resistance gradually decreased. This is attributed to the poor oxidation resistance of Mo5Si3, grain refinement and relative density decrease of the composites. In this experiment, a La2O3–Mo5Si3/MoSi2 composite was found to have optimal mechanical properties and high temperature oxidation resistance after adding 0.8 wt.%La2O3 and 16.3 wt.% Mo5Si3.