Grain Morphology and Fracture Mechanism of Al/Cu Joints by Ultrasonic Welding
Aiming at the brittle fracture of Al/Cu joints by ultrasonic welding,the Al/Cu ultrasonic welding experiments were carried out by adjusting the structural forms of copper and aluminum plates.The relationship among welding parameters such as welding amplitude,welding time,welding energy and peak power is established.The grain morphology and texture of Al/Cu joints by ultrasonic welding are analyzed by scanning electron microscopy(SEM)and electron back scatter diffraction(EBSD).The results showed that the welding energy and peak power increased linearly with the increasing welding time and welding amplitude,respectively.Under the action of welding pressure and high-frequency micro-dynamic friction,the solid phase connection of copper and aluminum plates is realized with different structural forms.The uniform distribution of dislocations is showed,dynamic recrystallization occurs,and a large number of equiaxed grain are generated in the microstructure of aluminum along the welding interface.The texture is transformed from the unit {001}<100>to the shear texture unit {111}<110>,and the texture strength decreases significantly.However,new dislocations does not form,the grain morphology and size are basically unchanged,and the texture strength is slightly increased in the microstructure of copper around the welded interface.The tensile test showes that the adjustment of the structure could change the fracture mode from the edge fracture of Al/Cu ultrasonic welding zone to the aluminum plate fracture,and improve the mechanical properties of Al/Cu joint by ultrasonic welding.
万方数据
维普
