Diffusion bonding of γ-TiAl alloy to Ti-6Al-4V alloy under hot pressure

The diffusion bonding of γ-TiAl alloy to Ti-6Al-4V alloy at different temperatures ranging from 1 073 to 1 173 K under an applied stress of 100 MPa for 2 h was studied. The observation of the microstructure reveals that sound joints between the γ-TiAl alloy and the Ti-alloy without any pores or cracks can be achieved through diffusion bonding at temperatures over 1 073 K under the applied stress of 100 MPa for 2 h. The bond is composed of two zones, and its width increases with the increase of bonding temperature. The EDS chemical composition profiles indicate that there is a diffusion flux of Al atoms from γ-TiAl alloy towards the Ti alloy and of Ti atoms in the opposite direction. The three point-bending of the joints bonded under different conditions was tested and the fracture mode was analyzed by SEM observation.