Reactive sintered dense carbon fiber reinforced high‐entropy boride composite using high‐entropy silicide as reactant

Abstract A novel reactive sintering strategy using high‐entropy disilicide, B 4 C, and carbon as initial materials is developed to fabricate dense carbon fiber reinforced high‐entropy diboride (HEB)‐based composite (C f /HEBs) at a relatively low temperature. The C f /(V 0.2 Nb 0.2 Cr 0.2 Mo 0.2 W 0.2 )B 2 –SiC composite (C f /HEB–SiC) successfully achieves nearly full densification (with a relative density of 99.2%) at 1800°C. The reactive damage of carbon fibers can be effectively restrained by preassemble carbon coating during the preparation process of the composite. Lower preparation temperature and effective coating protection contribute to the exertion of carbon fibers toughening capacity, consequently noticeably elevating the critical crack size ( α cr ) from 27.7 µm for HEB–SiC to 110.4 µm for C f /HEB–SiC. The current work provides a feasible way to substantially upgrade the damage tolerance of HEB–SiC and can be extended to other HEBs‐based ceramics.