Microstructure and strengthening behavior in high content SiC nanowires reinforced SiC composites

Abstract In this study, the high‐content SiC nw reinforced SiC ceramic matrix composites (SiC nw /SiC CMC) were successfully fabricated by hot pressing β‐SiC and sintering additive (Al 2 O 3 ‐Y 2 O 3 ) with boron nitride interphase modification SiC nw . The effects of sintering additive content and mass fraction (5–25 wt%) of SiC nw on the density, microstructure, and mechanical properties of the composites were investigated. The results showed that with the increase of sintering additives from 10 wt% to 12 wt%, the relative density of the SiC nw /SiC CMC increased from 97.3% to 98.9%, attributed to the generated Y 3 Al 5 O 12 (YAG) liquid phase from the Al 2 O 3 ‐Y 2 O 3 that promotes the rearrangement and migration of SiC grains. The comprehensive performance of the obtained composite with 15 wt% SiC nw possessed the optimal flexural strength and fracture toughness of 524 ± 30.24 MPa and 12.39 ± 0.49 MPa·m 1/2 , respectively. Besides, the fracture mode of the composites with 25 wt% SiC nw content revealed a pseudo‐plastic fracture behavior. It concludes that the 25 wt% SiC nw /SiC CMC was toughened by the fiber pull‐outs, debonding, bridging, and crack deflection that can consume plenty of fracture energy. The strategy of SiC nanowires worked as a main bearing phase for the fabrication of SiC/SiC CMC providing critical information for understanding the mechanical behavior of high toughness and high strength SiC nanoceramic matrix composites.