Wavy interface formation mechanism during magnesium–aluminum electromagnetic pulse welding

The wavy interface and its formation mechanism in magnesium–aluminum joints fabricated by electromagnetic pulse welding are investigated. This work reveals the wavy interfaces are produced by the shock wave-induced Kelvin–Helmholtz (K–H) instability. The shock wave generated at the collision point propagates forward along the collision angle and undergoes refraction and reflection at the boundaries, reaching the bonding interface and causing disturbances. It leads to K–H instability at the bonding interface, periodically generating waves. The re-reflection of the shock wave also leads to the secondary K–H instability, which creates the secondary wave with a smaller amplitude on the original wave. Based on this principle, a shock wave-induced K–H instability simulation model was also established to predict the wavy interface length.