Tailoring the microstructure of Mg-Al-Sn-RE alloy via friction stir processing and the impact on its electrochemical discharge behaviour as the anode for Mg-air battery

Constructing the magnesium alloy with fine grains, low density of dislocations, and weak crystal orientation is of crucial importance to enhance its comprehensive performance as the anode for Mg-air battery. However, this unique microstructure can hardly be achieved with conventional plastic deformation such as rolling or extrusion. Herein, we tailor the microstructure of Mg-Al-Sn-RE alloy by using the friction stir processing, which obviously refines the grains without increasing dislocation density or strengthening crystal orientation. The Mg-air battery with the processed Mg-Al-Sn-RE alloy as the anode exhibits higher discharge voltages and capacities than that employing the untreated anode. Furthermore, the impact of friction stir processing on the electrochemical discharge behaviour of Mg-Al-Sn-RE anode and the corresponding mechanism are also analysed according to microstructure characterization and electrochemical response.