The microstructure and properties of SiC/SiC-based composites fabricated by low-temperature melt infiltration of Al-Si alloy

Dense SiC/SiC-based composites were fabricated by introducing Ti₃Si(Al)C₂-based ceramics into Chemical Vapor Infiltration (CVI) fabricated porous SiC/SiC composites. For the purpose of reducing the damage to SiC fiber, the low-temperature melt infiltration of Al-Si alloy was utilized. The microstructure was observed, showing that the inter-bundle pores were filled by reaction-formed new phases and the porosity of SiC/SiC-based composites decreased to less than 5%. Owing to the densification of the matrix, higher thermal diffusivity was obtained compared with CVI fabricated SiC/SiC composites. The mechanical properties were also analyzed. The compressive strength and in-plane shear strength were 10.9% and 11.3% higher than those of CVI fabricated SiC/SiC composites, respectively.