Abstract:The Mg-Hg-Ga alloys are widely used in high power the seawater batteries. Mg-5%Hg-5%Ga alloy was melted and heat treatments at 573−773 K were performed for different times. The electrochemical and corrosion behaviors of the Mg-5%Hg-5%Ga alloy were studied by means of potentiodynamic, galvanostatic and electrochemical impedance spectroscopy(EIS). Scanning electron microscopy(SEM), energy dispersive spectrometry(EDS) and X-ray diffractometry(XRD) were employed to characterize the microstructures of the alloy. The results demonstrate that the best electrochemical activity occurs in the Mg-5%Hg-5%Ga alloy with homogeneously dispersed Mg₂₁Ga₅Hg₃ compound in α-Mg matrix. The most negative mean potential at 100 mA/cm² polarization current density can reach −1.928 V. The largest corrosion current density 19.37 mA/cm² of the Mg-5%Hg-5%Ga alloy appears in the Mg-5%Hg-5%Ga alloy with intergranular eutectic α-Mg and Mg₂₁Ga₅Hg₃.

Key words: Mg-Hg-Ga alloys; Mg anodes; seawater battery; electrochemical activity; corrosion resistance