Study On Laser Lap Welding Of Aluminum And Copper Dissimilar Metals

Pure copper has widely used to all kinds of industrial fields such as the electrical products,heat exchange equipment because of excellent thermal and electrical conductivity and so on.Although the electrical conductivity and thermal conductivity of aluminum alloy is lower than that of pure copper,it has many advantages which include low density and high specific strength and low cost and so on.With the development of industry,light-weighting and energy-saving and environment protection have become the important development themes,so the welding components of Al/Cu can cost-saving and light-weighting.However,the formation of Al/Cu intermetallic compounds(IMCs)is severely deleterious to the comprehensive properties of the weld metal of Al/Cu.The formation mechanism of Al/Cu IMCs is systematically investigated by changing the energy input of laser beam,and the microstructure and mechanical properties of Al/Cu dissimilar joints are improved by using Ni foil as a interlayer,and this mechanism is illustrated.In this paper,the laser welding experiment of Al/Cu dissimilar alloys is performed by the changing of laser power to change the heat input.The effect of heat input on the formation and growth of intermetallic compounds(IMCs)as well as the influence of IMCs on mechanical properties of Al/Cu dissimilar joints are investigated.The investigate results indicate that after the colling and solidify of weld pool,the WM zone forms a large amount of Al solid solution and a little of Al-Cu eutectic alloy,and the interface zone gradually generates the(Cu)solid solution and the coarse and coralline-shape Al2Cu IMC and the fine and wormlike Al-Cu eutectic alloy.The formation of brittle Al2Cu reduces the mechanism properties of Al/Cu dissimilar joints,the maximum tensile-shear strength value is about 99.8Mpa when the laser power is 2.45 kW.The maximum Vickers hardness value is in the interface zone,and the Vickers hardness of interface zone increases with the increase of laser power.Then using a Ni foil as a interlayer to improve the macro and micro structures,and mechanical properties.The analysis results manifest that the WM zone forms a large amount of Al solid solution and a little of Al-Cu eutectic alloy and Al Ni IMC after the colling and solidify of weld pool.The(Cu)solid solution initially is generated in the interface zone,and its thickness obviously increases because of the addition of Ni element to inhibit the diffusion of Al element.Then Al2Cu+AlNi IMCs is formed in interface zone,the coarse and coralline-shape Al2 Cu IMC transforms to the Al2 Cu IMC which consists of the fine and wormlike Al2Cu IMC and coarse and coralline Al2Cu IMC due to the addition of Ni element.The the Al-Cu eutectic alloy and Al Ni IMC are generate in the eutectic zone.The adding of Ni element can strengthen the tensile-shear strength of Al/Cu dissimilar joints,the maximum value can reach about 126.9Mpa.The fracture surface composed of the Al2Cu zone and Al-Cu eutectic zone is transformed into the Al2Cu zone and(Cu)solid solution zone.This paper illustrates the evolution mechanism of IMCs of laser-welded Al/Cu dissimilar lap weld metal,and explains the effect mechanism of Ni foil on microstructure and mechanical property of laser-welded Al/Cu dissimilar weld metal,which proposes theoretical and technological base for the high performance welding of Al/Cu dissimilar alloys.