Aluminium/magnesium hybrid structure has been paid increasing attention recently due to its excellent lightweight. However, aluminium/magnesium is easy to form pores, cracks, and massive intermetallic compounds when fusion welding is used. Friction stir welding is as solid-state method, which avoids the above-mentioned problems caused by fusion welding. This article systematically reviews recent progress in friction stir welding of aluminium/magnesium from temperature field, metal flow and weld composition. Moreover, the effects of control parameters on the temperature field, metal flow and weld composition are discussed objectively, respectively. Finally, this work puts forward some problems that need to be solved urgently in the future based on summarising the recent progress of friction stir welding of aluminium/magnesium.

5A06 Aluminum (Al) alloy and AZ31B magnesium (Mg) alloy with 20 mm thickness were successfully butt joined by friction stir welding. In order to control the composition of Al and Mg alloys along thickness direction, an inclined butt joint was designed in this study. The microstructure and phase identification at the interface of Al/Mg joints were examined using scanning electron microscopy with an energy-dispersive spectroscopy and Micro X-ray diffraction. The results indicated that there were two different formation mechanisms of intermetallic compounds at the interface of thick plate Al/Mg joint. The first was constitutional liquation, and eutectic structure consisting of Al₁₂Mg₁₇ and Mg solid solution existed at the top and upper-middle of the Mg side interface. The second was diffusion reaction, and the two sub-layers of Al₁₂Mg₁₇ and Al₃Mg₂ formed at the lower middle and bottom of the Mg side interface. In addition, the diffusion thickness values of Al₁₂Mg₁₇ and Al₃Mg₂ layers decreased gradually from the lower middle to bottom of the Mg side interface. As the position changes from the middle to the bottom near the Mg side interface, the diffusion coefficient of Al₃Mg₂ phase rapidly decreases from 3.14 × 10⁻¹² m²/s to 6.9 × 10⁻¹³ m²/s and the diffusion coefficient of Al₁₂Mg₁₇ phase decreases from 6.8 × 10⁻¹³ m²/s to 1.5 × 10⁻¹³ m²/s.