Reaction Brazing of C/SiC Composites to Nb with Equiatomic Ti-Ni Composite Foils

C/SiC composites and Nb were successfully reaction brazed with equiatomic Ti-Ni composite foils in vacuum. The microstructure and shear strength of the brazing joints, the reaction path during brazing were all studied. The results indicated that multistage reactions occurred during brazing. Including reactions between Ti foils and Ni foils, reactions between Ti-Ni liquid and C/SiC & infiltration of Ti-Ni liquid to C/SiC pores, reactions between TiNi and Nb, reactions between TiNi-Nb eutectic liquid and C/SiC & infiltration of TiNi-Nb liquid to C/SiC pores, as a result of these reactions, the microstructure of the brazed joints at the dense part of C/SiC and at the pore part of C/SiC was different. The microstructure of the typical brazed joint at the dense part of C/SiC can be expressed as (C/SiC) /discontinuous TiC + continuous (Ti,Nb)C / (Ti,Nb)₂Ni / (Ti,Nb)₂Ni particles +Ti-Ni-Nb-Si compound + TiNi-(Nb,Ti) eutectic / Nb. The microstructure of the joint at the opening pore of C/SiC is the same as that at the dense part, whereas the joint at the distal pore of C/SiC were composed of TiNi, Ti₂Ni and TiC. Owing to the good combination property of TiNi-(Nb,Ti) eutectic, high interfacial strength of C/SiC and filler metal, and the contribution of filler metals filled in C/SiC pores, the C/SiC and Nb joints exhibited high shear strength of 188MPa at room temperature and of 128MPa at 800°C.