Active joining of Ti–6Al–4V with electroplated Cu thin film

Joining of Ti–6Al–4V with thin film copper fillers was developed using an active infrared processing technique. The process includes rapid infrared heating of the specimen to 1125 °C, and holding at that temperature for 60 s in flowing argon without vacuum, then followed by rapid cooling. The copper thin film filler was electroplated to various thicknesses: 1, 2, 4 and 8 μm. Excellent wetting between copper and Ti–6Al–4V was observed in all joints. High joint shear strengths were obtained for all joints. The highest joint strength, 616±10 MPa, was obtained with 2 μm filler thickness. This joint strength is significantly higher than the shear strength of pure copper, 174 MPa, or Ti–6Al–4V, 542 MPa. When the filler material was only 1 μm, the joint zone was not completely filled. X-ray diffraction analysis on the as fractured joint surface revealed the presence of intermetallic compounds when joined with 4 and 8 μm copper fillers but it disappeared when joined with 1 and 2 μm copper fillers.