Diffusion bonding of TiAl and GH3536 superalloy with Cu and Cu-Ti as interlayers

TiAl alloy was joined to GH3536 superalloy with diffusion bonding method using Cu foil and Cu-Ti alloy as the interlayers.The microstructure and property of the joints bonded at different conditions were tested.The results showed that the joint bonded at the condition of 935℃/10 MPa/1 h with Cu foil interlayer,was mainly composed of Ti(Cu,Al)₂,AlCu₂Ti and AlNi₂Ti phases.However,some microcracks appeared throughout the joint and the corresponding average shear strength at room temperature was only 31 MPa.Liquid-phase diffusion bonding between TiAl and GH3536 was investigated by using Cu-Ti interlayer at 935℃.Under the bonding condition of 3 MPa and 10 min,residual phases of the Cu-Ti interlayer were visible in the central part of the joint,with the thickness of about 5 μm.Prolonging the holding time to 1h,several homogeneous layers appeared in the joint,and it exhibited the maximum shear strength of 180 MPa.AlNi₂Ti phase was formed in the joint bonded at an increasing pressure of 20 MPa and with the holding time of two hours,while its average shear strength decreased to 90 MPa.