LAUSR

Liquid filler metals often experience electromigration (EM) effects during resistance brazing due to the high current density, which can affect the microstructure of the joint and reduce its strength. However, to date, few studies have investigated this effect. Here, a Zn–Al alloy filler metal was used to braze 6063 Al alloys using direct-current resistance brazing. We clearly observed that EM occurred and analyzed its effect on the microstructures and morphology of joints. Al atoms migrated from the negative side to the positive side under a combined effect of the electric field and chemical gradient, while Zn atoms migrated in the opposite direction due to a back stress gradient. Further, growth of a solid solution layer at the positive side was inhibited by the back stress gradient, which also promoted growth of a similar layer at the negative side.