Continuous drive friction welding of commercial pure aluminum to copper: Metallographic and mechanical characterization of various cross-sections

An electrically and mechanically sound joint between aluminum and copper is essential in modern manufacturing, particularly in the field of e-mobility, where the demand for integrated, lightweight, and high-performance conductors continues to grow. However, because of the distinct metallurgical characteristics of these materials, their joining presents significant metallurgical and process-related challenges, including the formation of brittle intermetallic compounds (IMCs). Rotary friction welding (RFW) has emerged as a promising solid-state joining technique, enabling high-integrity dissimilar material bonds through the reduction of heat input and reducing IMC formation. This study investigates the metallurgical and mechanical properties of the aluminum-copper joints produced by RFW. A comprehensive microstructural analysis was conducted using scanning electron microscopy (SEM) on both fracture surfaces and cross-sectional samples. Energy-dispersive X-ray spectroscopy (EDX) was employed to examine the IMC phases at the weld interface, providing insights into their formation and distribution. To evaluate the mechanical performance of the joints, tensile tests were performed on specimens with varying diameters, allowing for an assessment of the weld integrity across different residual cross sections. This approach enabled the determination of whether a strong bond extends throughout the weld region. In addition, hardness measurements were conducted to further characterize the mechanical properties of the joint. The results provide a deeper understanding of the microstructural evolution and mechanical behavior of aluminum-copper RFW joints. The insights gained contribute to optimizing joint performance and the development of reliable bimetallic connections for industrial applications.