Investigation of variations of metallurgical and morphological phenomena of interface in the magnetic pulse welding of Al–Cu

Abstract

This study investigates the bonding interface characteristics, formation mechanisms of metallurgical bonds, and intermetallic compounds in Al–Cu joints produced by magnetic pulse welding (MPW) using an E-type coil. Welding was conducted at a discharge voltage of 16 kV and an air gap of 1 mm. Field-emission scanning electron microscopy (FE-SEM) analysis revealed that the bonding interface characteristics vary with increasing distance from the collision centerline. In addition, the X-ray diffraction (XRD) analysis identified the formation of intermetallic compounds of AlCu, AlCu₄ and Al₄Cu₉ at the bonding interface. The collision angle increases and collision energy decreases with distance from the centerline, resulting in two distinct zones: a high-shear zone near the collision centerline (Zone 1) and a low-shear zone near the bond edge (Zone 2). The AlCu intermetallic compound was predominantly formed in the high-shear zone, while AlCu₄ and Al₄Cu₉ were observed in the low-shear zone. The formation mechanism of these intermetallic compounds is attributed to solid-state diffusion, as no signs of melting were detected in the transition zones of the bonding interface, except in the porous zone. Additionally, the bonding interface exhibited higher strength compared to the base metals of Al and Cu.