Microstructure and mechanical properties of ZrO2-reinforced MoSi2 matrix composites

The purpose of the present investigation was to explore microstructure and mechanical properties of two types of composite materials with different amounts of secondary phase (10% and 15% ZrO2), and their comparison with monolithic MoSi2. Following metallographic analyses the identification of phases and residual pores in microstructure was realised. The main criteria for assessment of mechanical properties were hardness, mechanical strength, and fracture toughness determined by two different methods. The results showed that materials with added ZrO2 particles had better mechanical properties compared to the monolithic one and these properties improved with increase of the ZrO2 content. Comparison of the two methods of fracture toughness measurement indicates better sensitivity and reliability of the IS method which is less influenced by human factor. The results of EDX analysis showed that the microstructures of the toughened materials contain monolithic MOSi2 phase, Mo5Si3 phase and secondary ZrO2 phase.