Microstructures and mechanical properities of diffusion bonded Ti₂AlNb and GH4169 jionts by using Nb+Ni interlayer

Vacuum diffusion bonding of Ti₂AlNb and GH4169, by inserting metal foils of Ni+Nb as interlayer, was studied experimentally under the conditions of bonding temperature 950-1100°C, axial pressure 20 MPa and holding time 20-120 min. The joints microstructures and bonding mechanism were studied by SEM and EDS analyses. The results show that Ti₂AlNb and GH4169 could be well bonded with metal foils of Ni+Nb as interlayer. There were six reacted layers between Ti₂AlNb and GH4169, and the layers were Fe-Ni-Cr solid solution, Ni₃Nb, Ni₆Nb₇, residual Nb, Ti-Nb solid solution, O phase with high Nb, orderly, from the GH4169. When sheared, the joint fractured in the Ni₆Nb₇ layer which between the Ni₃Nb layer and the residual Nb layer. The maximum shear strength was 460.3 MPa at 1050°C, 20 MPa, 40 min.