Microstructure dependent physical and mechanical properties of spark plasma sintered ZrB2-MoSi2–SiCw composites

Abstract A comparative evaluation has been carried out off the physical and mechanical properties of ZrB2–20 vol% MoSi2 composites reinforced with 5, 10 and 20 vol% SiC whiskers (SiCw). The abovementioned hybrid composites have been densified by spark plasma sintering (SPS) at 1600 °C for 10 min. The present study focuses on the effect of the quantity of SiCw on the densification, electrical conductivity, hardness, and fracture toughness ZrB2–MoSi2–SiCw composites in detail. Microstructural characterization suggests that SiCw restricts the grain growth of ZrB2 during densification. The electrical conductivities of the ZrB2–MoSi2–SiCw composites have been found to vary in the range ~2.4–3.5 × 106 S/m, and it reduce with increasing SiCw content. Results exhibit that the indentation fracture toughness of ZrB2–20 vol% MoSi2 improves ~70%, ~112% and ~130% with an addition of 5, 10 and 20 vol% SiCw, respectively. An increase in SiCw content leads to more amount of crack deflection and crack arrest that successively improves the fracture toughness of the composites.