SiC fiber strengthened Si-14Ti high-temperature filler alloy for brazing SiCf/SiC and C/C composites

SiC fibers were employed as the reinforced and tough phase in the Si-14Ti filler alloy for joining SiCf/SiC composites and C/C composites. The joint microstructure and regulation mechanism of SiC fibers were investigated for the first time. The morphology evolution of SiC fibers was also observed through the chemical reaction experiment between fibers and liquid Si-14Ti alloy. SiC nanocrystals that composed the SiC fibers experienced degradation and regrowth progress in the high-temperature Si-14Ti melt, and then transformed into coarse SiC in the brazing seam. Meanwhile, the liquid Si-14Ti filler alloy filled the intergranular space among the newly generated SiC blocks, and reacted with the SiCf/SiC and C/C composites to form SiC interfacial layers. The microstructure of the SiCf/SiC-C/C joint finally evolved into SiC interfacial layer/SiC-TiSi2 multiphase ceramics and Si-TiSi2 eutectic structure/SiC interfacial layer. Finally, a favorable joint shear strength of 48 MPa was obtained when brazing at 1420 degrees C.