Electrochemical Behavior of Mg-Al-Zn-Ga Alloy as Anode Materials in 3.5 wt.% NaCl Solution

The microstructure and electrochemical behaviors of Mg-Al-Zn and Mg-Al-Zn-Ga alloys as anode materials were investigated by morphology observation, composition analysis, phase identification, and electrochemical tests. The experimental results suggest that Ga alloying can refine the grains of the Mg-Al-Zn alloy by promoting second-phase segregation, which comprises Mg17Al12 and GaMg2. The comparison of discharge tests indicates that adding Ga to the Mg-Al-Zn alloy can negatively shift the discharge potential, provide a high current density, promote the formation of tiny and thin products, and improve the utilization efficiency. Meanwhile, the addition of Ga can increase the corrosion resistance of Mg-Al-Zn alloy because the Ga alloying promotes the segregation of the intermetallic phases in the Mg matrix. The intermetallic phases disperse in isolate states in the Mg matrix, resulting in their falling off from the substrate once their adjacent Mg is exhausted and subsequently ceasing the micro-galvanic corrosion. The Mg-Al-Zn-Ga alloy with higher corrosion resistance performs better discharge activity than that of Mg-Al-Zn alloy in 3.5 wt.% NaCl solution, implying that the Mg-Al-Zn-Ga alloy is a promising anode material for seawater-activated battery.