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

A novel reactive sintering strategy using high-entropy disilicide, B4C, and carbon as initial materials is developed to fabricate dense carbon fiber reinforced high-entropy diboride (HEB)-based composite (Cf/HEBs) at a relatively low temperature. The Cf/(V0.2Nb0.2Cr0.2Mo0.2W0.2)B2-SiC composite (Cf/HEB-SiC) successfully achieves nearly full densification (with a relative density of 99.2%) at 1800 degrees 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 (alpha cr) from 27.7 mu m for HEB-SiC to 110.4 mu m for Cf/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. Highly dense Cf/(V0.2Nb0.2Cr0.2Mo0.2W0.2)B2-SiC composite (Cf/HEB-SiC) with a relative density of 99.2% was successfully synthesized at a relatively low temperature of 1800 degrees C via the reactive sintering strategy adopting high-entropy disilicide as a reactant. Reactive erosion at the fiber/matrix interface can be effectively prevented by prefabricated fiber coating. Lower preparation temperature and effective coating protection release the toughening abilities of carbon fibers thoroughly, significantly enhancing the reliability of Cf/HEB-SiC composite. image