Study On Microstructure And Conductivity Of Welding Joint Of Aluminum-Copper Dissimilar Metals Welding-Brazing

In this paper,the relationship between the microstructure and electrical conductivity of aluminum-copper joints obtained under different experimental parameters is studied.The solid-liquid bimetal compound casting method was used to obtain the aluminum-copper composite connector of 1060 aluminum plate and T2 copper plate.The welding method of ER4043,ER4047 and ER1100 was obtained by pulse bypass coupling MIG welding.Under different test parameters,The connection interface of the connection interface is analyzed during the process of finding the interface and the conductivity of the interface is very different.For the solid-liquid composite connection,the diffusion between the atoms is more fully combined with the closer,the composition of the joints closer to the balance between the aluminum and copper reaction.The analysis of aluminum and copper interface found that the microstructure of aluminum-copper interface under high temperature insulation was relatively smooth.When the energy of diffusion is sufficient,the product of aluminum-copper interface will increase gradually.According to the preliminary work of the use of pulsed double electrode-gas metal arc welding joint conductivity analysis process found that the welding of pure aluminum wire conductivity is less than the conductivity of silicon wire,this problem on the interface of the joint analysis,when the wire Containing silicon will increase the weldability of the joint and increase the tightness of the joint.In the analysis of the intermetallic compound layer,it was found that the thickness of the intermetallic compound layer of the 4043 filler joint was thinner than the thickness of the intermetallic compound of the 4047 filler joint.When the silicon content was constant,the silicon element had a resistance to the intermetallic compound a certain inhibitory effect.In the process of annealing the welded joint,the appearance and composition of the joint were changed,especially when the annealing temperature was eutectic temperature,the CuAl2 phase changed from the block before annealing to obvious dendritic shape,and the CuAl2 Phase dendrites and dendrites precipitate a large number of silicon elements.When the joints of different connections were analyzed,it was found that the intermetallic compound layer was produced with the heat and the length of the time.Due to the particularity of the welding heat source,the intermetallic compounds produced at the interface of the welded joint were CuAl,CuAl2 and CuAl2 Eutectic structure,but according to the existing theory Cu9Al4 is followed by CuAl2 produced by the second phase,but the detection of welded joints without Cu9Al4,it can be inferred that the formation of the phase after satisfying the conditions still need a certain breeding time.Analysis of the conductivity of the joint under different connection modes revealed that the conductivity of the joint was reduced as the thickness of the intermetallic compound layer increased and that the conductivity of the joint was better when the transition layer was in a continuous and single.