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Mg–0.5Bi–0.5Sn alloys with and without microalloying with 0.5 wt% Mn were subjected to extrusion, and the effect of Mn microalloying on the microstructural characteristic and corrosion behavior of the extruded alloys was investigated. The results indicated that the average grain size and the density of dislocations decreased, and a new Mg26.67Mn65.47Fe7.86 second phase as well as grain boundary segregation of Sn atoms could be observed in certain micro-regions of the extruded dilute Mg–0.5Bi–0.5Sn–0.5Mn alloy. The tailoring of microstructure resulted in the significant enhancement in corrosion resistance (Rp increased from 1095.91 Ω cm2 to 5008.79 Ω cm2). In addition, grain boundary segregation resulted in intergranular corrosion and led to the dissolution of Sn atoms. Hence, the dissolution rate of the matrix in Mg–0.5Bi–0.5Sn–0.5Mn alloy could be inhibited by the corrosion product film containing an intermediate product (SnO2).

Mg-0.5Sn-0.5 Mn-0.5Ca (wt.%) alloys with different microstructures are designed through casting and extrusion with and without homogenization treatment prior to extrusion (HPE). The influence of HPE treatment on the microstructural characteristics and resultant discharge properties of Mg-Sn-Mn-Ca alloy in extruded condition as anode for Mg-air battery was investigated. HPE treatment exerts a prominent effect on the grain structure and orientation, distribution of the second phase particles as well as the dislocation density of the extruded alloy. The HPE alloy exhibits a distinctly high cell voltage together with specific energy compared with that of Non-HPE one. Intermittent discharge tests confirm that the HPE alloy possesses a more excellent discharge activity and more stable discharge process than the Non-HPE one. All results demonstrate that the HPE alloy is an attractive anode material for Mg-air battery with long-term storage and under intermittent discharge.

In this work, in order to reveal the role of crystallographic orientation in the electrochemical and discharge behaviors of the extruded diluted Mg-0.5Sn-0.5Zn-0.5Ca (wt.%) alloy through investigating the longitude surface (LS) and transversal surface (TS). The results show that the LS sample is mainly consisted of (0001) orientated grains, while the TS one is composed of (10-10)/(11–20) orientated grains. Although the self-corrosion rate for TS sample is higher than that of the counterpart as a result of the non-basal planes possess lower surface energy and higher activation energy, the real-time self-discharge rates for both samples are similar at constant applied current density. Nevertheless, the TS sample exhibits a remarkably higher anodic efficiency than that of the LS one, which can be attributed to the uniform dissolution of the substrate along with the weakened chunk effect (CE). Additionally, the Mg-air battery with the TS sample as anode exhibits a more stable discharge course and higher cell voltage due to the loose discharge products as well as enhanced discharge activity.

In this study, the microstructural characteristic, electrochemical behavior and discharge performance of extruded Mg-xBi (x = 0.5, 1.0 and 2.0 wt%) anodes are systematically evaluated. The results show that the cell voltage and anodic efficiency deteriorate as the Bi addition increased in galvanostatic discharge process. In addition, intermittent discharge behavior also confirms that the Mg-0.5Bi anode can output both excellent discharge activity and stable discharge process than the counterpart ones. This is attributed to the negative open current potential (OCP) value and thin and loose discharge products film as well as mitigated “chunk effect” (CE). Therefore, extruded Mg-0.5Bi alloy is a promising anode material for Mg-air battery.

In this study, the discharge behaviors of extruded low-alloyed Mg–Bi–Ca alloys in an aqueous electrolyte (3.5 wt% NaCl solution) were investigated using electrochemical techniques. The Mg–1Bi-0.5Ca alloy showed more negative discharge potential and higher anodic efficiency compared with the Mg–1Bi alloy during half-cell testing. Furthermore, the discharge morphologies of the Mg–1Bi-0.5Ca alloy showed loose and thin discharge products, along with numerous cracks, these features promoted diffusion of the NaCl solution into the discharge products, enhancing the discharge activity. The Mg–air battery with a Mg–1Bi-0.5Ca anode showed the higher cell voltage and power density at all current densities. Hence, the Mg–1Bi-0.5Ca alloy has great potential for further development as an anode material for Mg–air battery.

Controlling the microstructure and discharge performance of Mg-based alloys is of great importance and aimed at optimizing magnesium anode materials to the level required for power source applications. In this study, the microstructure along with discharge properties of extruded Mg–Sn–Zn–Ag alloys with Sn content ranging from 2 wt.% to 8 wt.% are investigated. The results indicate that the Mg–4Sn–1Zn–1Ag alloy exhibits the most negative discharge potential during the half-cell test than the other alloys investigated in this study. Moreover, a Mg-air battery with a Mg–4Sn–1Zn–1Ag alloy as the anode provides a relatively high cell voltage together with power density compared with the counterpart battery. Furthermore, the microscopic mechanism of an anode material exhibiting an excellent discharge performance is systematically discussed in terms of the second phase, dynamic recrystallization, crystal orientation and discharge product film.