A Novel Dissimilar Metal Joining Technology of Cu and Al Thin Plates Utilizing Eutectic Melting by Frictional Heat

A novel butt-joining technology of Cu and Al thin plates was developed, in which the edge of a Cu plate over the edge of an Al plate were pressed by the rotary tool with a truncated cone-shape in the atmosphere. Joining experiments were performed using 1mm thick C1020 plates and 1mm thick A1050 plates. The joint quality was investigated by observation and analysis of the joining interface and by tensile testing of dumbbell specimens fabricated with the Cu-Al joined bodies. The results clarified that the eutectic melting between Cu and Al was caused by pressure and frictional heat, and that the overlapped portion deformed into a butt joining shape while extruding the eutectic melt from the joining interface. A slant joining interface was formed between the C1020 and A1050 plates, and the film-like layer presumed to be consisted of CuAl 2 and CuAl were generated at the entire joining interface. The thickness of the layer ranged from 0.6 to 1.3 μ m. The average ultimate tensile strength of the dumbbell specimens was 92MPa, and the section of A1050 approximately 2mm away from the joint fractured in the tensile testing. This indicates that the Cu-Al joint had a higher strength than 92MPa.