Study On Microstructure And Properties Of Ultrasonic Welded Joint Of Copper And Aluminum

Due to its excellent conductivity and ductility,copper and its alloy are widely used in various fields of industrial production,but the price of copper and high density low reserves,it is hard to meet the modern industrial production of"economy"and"light",meanwhile it usually be used with other metal joint in order to achieve the effect of complementary advantages,The most common copper-aluminum joint is widely used in the transmission wire industry.In this paper,Ultrasonic welding machine be used to conduct ultrasonic welding test on copper/aluminum metal.Using XRD diffraction,SEM scanning electron microscope(SEM),EDS energy spectrum analysis,the tensile shear mechanics test,electrochemical corrosion and other characterization methods of ultrasonic welded joint interface group,the proliferation of elements in the weld,the welding process of the interface reaction,phase component and corrosion resistance was carried on the system research,the diffusion of copper/aluminum atoms during welding was simulated by Lammps molecular dynamics software,The results show that the effective bonding occurs when the welding pressure is0.4MPa,the amplitude is 95%,and the welding energy is 2000J.The main intermetallic compounds in the weld are Al Cu and Al₂Cu.The tensile test shows that the brittle fracture occurs at the solder joint and the failure mode is solder joint failure.The addition of zinc interlayer,under the same experimental conditions,the welding energy of 1000J can produce uniform weld,which reduces the energy required for effective connection.Through thermocouple temperature measurement,it is found that the interlayer can improve the peak temperature of interface in the welding process,which is conducive to element diffusion.The results show that Cu Zn₅ and Al-Zn eutectic structures generated in the weld.In order to optimize the process parameters,the shear performance of the experimental sample with the interlayer was tested.Combined with the response surface mathematical analysis,the influence of the interaction between parameters on the shear strength of the solder joint was explored using software,and the conclusion was the influence of welding pressure was the most significant.Electrochemical analysis shows that the corrosion resistance of solder joints decreases after the addition of zinc interlayer,but it is still higher than the base aluminum,so the base aluminum corrodes first in actual use.The diffusion process between copper and aluminum was simulated,and the input distribution function and mean azimuth shift were obtained by pressing the model for 2ns at a temperature of 800K at a pressure of 50MPa.Then the stress-strain curve was obtained by stretching the model for 0.25ns.The work hardening phenomenon was observed from the stress change and the number of dislocations.