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 ZrB 2 –20 vol% MoSi 2 composites reinforced with 5, 10 and 20 vol% SiC whiskers (SiC w). 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 SiC w on the densification, electrical conductivity, hardness, and fracture toughness ZrB 2 –MoSi 2 –SiC w composites in detail. Microstructural characterization suggests that SiC w restricts the grain growth of ZrB 2 during densification. The electrical conductivities of the ZrB 2 –MoSi 2 –SiC w composites have been found to vary in the range ~2.4–3.5 × 106 S/m, and it reduce with increasing SiC w content. Results exhibit that the indentation fracture toughness of ZrB 2 –20 vol% MoSi 2 improves ~70%, ~112% and ~130% with an addition of 5, 10 and 20 vol% SiC w , respectively. An increase in SiC w content leads to more amount of crack deflection and crack arrest that successively improves the fracture toughness of the composites. Highlights • Spark plasma sintering successfully densified the ZrB 2 –MoSi 2 –SiC w composites with varying amount of SiC w • With the increase in SiC w resulted in enhancement in fracture toughness of ZrB 2 –MoSi 2 –SiC w composites. • The fracture toughness of ZrB 2 –20 vol% MoSi 2 improves by about ~130% with the addition of 20 vol% SiC w. • Microstructure suggests toughening mechanism mainly controlled by crack deflection and interfacial debonding. [ABSTRACT FROM AUTHOR]