Nano-diffusion bonding of Ti2AlNb to Ni-based superalloy

Abstract Ti 2 AlNb alloys are one of the most promising structural materials with potential applications in aero-engines. Dissimilar joining of Ti 2 AlNb alloy to Ni-based superalloy was carried out with diffusion bonding method using Cu + Ti composite foil and Cu/Ti nano-laminated foil, respectively. Joint microstructures were analyzed with SEM, EPMA, XRD and TEM. The joint bonded with Cu + Ti composite foils presented shear strength of 114–167 MPa at room temperature. For the joint bonded with Cu/Ti nano-laminated foil, Ti 2 Cu rather than TiCu reactive layer was visible and the sizes of phases were about 0.5–2 μm. A larger area of α-Ti phase was formed and the thickness of intermetallic compounds area decreased from the 35 μm to 18 μm. Raising bonding temperature could enhance the metallurgical bonding and improve the bonding quality. The joints bonded at 900 °C/20 min/20 MPa presented the maximum shear strength of 305 MPa, increased about 82% compared with the Cu + Ti composite foil.