Microstructure, mechanical, and thermal properties of in situ-synthesized (ZrB2+SiC)/Zr2[Al(Si)]4C5 composites

Based on thermodynamic analysis, densified 30 vol% (ZrB2+SiC)/Zr2[Al(Si)]4C5 composites were prepared by in situ hot pressing at 1850 °C. The microstructure, mechanical, and thermal properties of the composites were characterized. As reinforcements, ZrB2 and SiC incorporated by in situ reaction significantly improved the mechanical and thermal properties of Z2[Al(Si)]4C5. Compared with monolithic Z2[Al(Si)]4C5, the composite showed superior Young's modulus (425 GPa), room temperature flexural strength (621±33 MPa), high-temperature flexural strength (404±13 MPa, 1300 °C, air), fracture toughness (7.85±0.29 MPa m1/2), and Vickers hardness (16.7±0.4 GPa). The composite also exhibited a similar heat capacity to but significantly higher thermal conductivity than Z2[Al(Si)]4C5.