Effect of in situ synthesized TiB whisker on microstructure and mechanical properties of carbon-carbon composite and TiB_w/Ti-6Al-4V composite joint

Carbon-carbon composite (C-C composite) and TiB whiskers reinforced Ti-6Al-4V composite (TiB_w/Ti-6Al-4V composite) were brazed by Cu-Ni+TiB₂ composite filler. TiB₂ powders have reacted with Ti which diffused from TiB_w/Ti-6Al-4V composite, leading to formation of TiB whiskers in the brazing layer. The effects of TiB₂ addition, brazing temperature, and holding time on microstructure and shear strength of the brazed joints were investigated. The results indicate that in situ synthesized TiB whiskers uniformly distributed in the joints, which not only provided reinforcing effects, but also lowered residual thermal stress of the joints. As for each brazing temperature or holding time, the joint shear strength brazed with Cu-Ni alloy was lower than that of the joints brazed with Cu-Ni+TiB₂ alloy powder. The maximum shear strengths of the joints brazed with Cu-Ni+TiB₂ alloy powder was 18.5MPa with the brazing temperature of 1223K for 10min, which was 56% higher than that of the joints brazed with Cu-Ni alloy powder.