Diffusion of Mg/Al Interface Under Heat Treatment After Being Manufactured by Magnetic Pulse Welding

There is limited research on dissimilar joints of RE-containing Mg alloys and Al alloys, and the diffusion of elements is fundamental for the properties of Mg/Al interfaces. In this study, samples were manufactured by magnetic pulse welding (MPW) with plates of the AA1060 aluminum alloy and the as-cast Mg–4.80Gd–1.92Zn (in wt.%) alloy, and the effects of heat treatments at 200 °C and 250 °C, from 1 h to 4 h, on the diffusion of the Mg/Al interface were investigated. The results indicated that diffusion of the Mg and Al elements occurs at 250 °C for no less than 2 h, since Gd and Zn are mainly concentrated in precipitates in the Mg–4.80Gd–1.92Zn alloy. When the heat treatment time at 250 °C is increased from 2 h to 4 h, the width of the Mg/Al interface increases from ~15 μm to ~20 μm. At positions near precipitates in the Mg alloy, the diffusion of Al atoms into the Mg lattice can be hindered by the precipitates, leading to an abnormal decrease in the width of the interface, which is also related to the difficulties of the Mg element diffusing into the Al matrix.