Study on Microstructure and Mechanical Properties of Aluminum/Copper Ultrasonic Welded Joints

The concave and convex surfaces were machined on the surface of aluminum and copper plates, then the chimeric joints between the aluminum and copper plates were prepared by using ultrasonic welding. The influence of the contact area and shape between plates on the ultrasonic welding quality, temperature, the joint mechanical properties and failure form were explored under the same energy input. The results show that when ultrasonic welding under the same energy input, the welding temperature trend is that the welding temperature of the aluminum-copper original joint without surface treatment for plates is higher than that of the chimeric joints, the increase of contact area consumes more energy, the heat produced during ultrasonic welding process is reduced. The strength of different aluminum-copper chimeric plate joints is basically consistent, and the strength increases by 7.06%-9.39% compared with that of the original joint, all the joints strength is bigger than that of the base material. However, the peak load of the aluminum/copper chimeric joint is lower than that of the aluminum/copper original joint, and the decrease of the plate thickness is the main reason for the decrease of peak load.The joint failure occurs at the first row of aluminum welding tooth, the aluminum is ductile fracture and a large number of dimples are found at the fracture.