Microstructure and mechanical properties of Al/Cu dissimilar metals welding-brazing joint

Dissimilar metals of 1060 aluminum and T2copper were joined with lap joint by pulsed double electrode gas metal arc welding-brazing with ER5356 AlMg5filler wire. Microstructure, elements composition and mechanical properties of joint were studied. The results showed that good-looking，continuous and uniform，defectless welds could be obtained with proper welding parameters．Welded joints transit from copper side with intermetallic compound (IMC) layer, Al-Cu eutectic to welding seam. The IMC layer is composed of Al2Cu phase, and the weld zone is composed of α(Al) solid solutions and α(Al)+S(Al2CuMg)/θ(Al2Cu) eutectic in the grain boundary. The thickness of IMC layers increases with the increase of welding heat input, while the tensile load of joint increases at first and then decreases, which is related to the wetting and spreading of the weld on the copper base material. Tensile test results show that the joint fractures at the heat affected zone of aluminum base metal or interface layer between the weld and the copper base metal.