Brazing high Nb containing TiAl alloy using Ti-28Ni eutectic brazing alloy: Interfacial microstructure and joining properties

High Nb containing TiAl alloy (Ti-45Al-8.5Nb-(W, B, Y) (at%)) was successfully brazed by using Ti-28Ni (wt%) eutectic brazing alloy. The interfacial microstructure was characterized by SEM, EDS and XRD. Especially the effect of brazing temperature on interfacial microstructure and joining properties was investigated in details. Microstructure analyses results showed that the brazed joints presented a symmetrical characteristic and mainly consisted of Ti3Al, Ti2Ni and B2 phases. As the brazing temperature increased, the amount of Ti2Ni phase gradually decreased, meanwhile the amount of B2 phase increased significantly, while the continuous Ti3Al layer was insensitive to the brazing temperature. The maximum shear strength reached 204 MPa when the joints were brazed at 1100 °C for 10 min. Brittle fractures were observed in all of the brazed joints after shear test although the fracture location changed obviously with the increase of brazing temperature.