Interfacial microstructure of multi-layered Al–Cu joint by electromagnetic pulse welding

Abstract

The necessity of the multi-layered aluminium (Al) tabs to copper (Cu) busbars for electric vehicle (EV) batteries is increasing. Electromagnetic pulse welding (EMPW) is applicable to the welding of conductive dissimilar/similar materials. In this work, three Al sheets and a single Cu sheet are joined by the EMPW technology. The layer-wise tensile lap shear properties of the multi-layered Al–Cu EMPW joint are evaluated. The layer-wise interfacial microstructures of the joint parallel to and perpendicular to the welding direction are studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS). The results showed that every layer achieved metallurgical bonding. The Al sheets were formed to be whole. There were three types of interfaces at the Al–Cu interface parallel to the welding direction: flat interface, wave interface, and irregular wave interface. The transition zone is found at the Al–Cu interface perpendicular to the welding direction. Due to the impact, the grains near the Al–Cu interface and Al–Al interface are both refined. Thus, the well-bonded multi-layered Al–Cu joint is successfully obtained via EMPW. The results can offer help in the manufacturing of EVs.

Keywords

• Electromagnetic pulse welding (EMPW)
• Multi-layered Al–Cu joint
• Interfacial microstructure
• Tensile lap shear