Microstructure of reactive composite brazing joints of SiC ceramics and Ti alloy by using Ag-Cu-Ti-(Ti+C) as bonding material

By using the mixed powder of Ti,C(mole ratio of Ti to C is 1∶1) powders for in-situ synthesizing TiC in 15%30%TiC(volume fraction) and alloying 67.6%Ag-26.4%Cu-6%Ti(mass fraction) powder as vacuum non-pressure brazing material,sound brazed joints of SiC ceramics /Ti alloy were acquired at 920℃ for 30min.The joints were investigated by X-ray diffractrometry,scanning electron microscopy,and energy dispersive spectrometry.The results show that TiC grains are in-situ synthesized and distribute in Ag and Cu-Ti phases of the bonding layers,distinctly lowering the thermal stress of the joints.However,excess amount of(Ti + C) powder easily brings about the formation of pores and incomplete reactions of Ti and C in the bonding layers,which are detrimental to the joints' strengths.During brazing process,Ti element in Ti-alloy and Cu element in the bonding layer interdiffuse.