Influence of Mg21Ga5Hg3 compound on electrochemical properties of Mg-5%Hg-5%Ga alloy

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 alpha-Mg matrix. The most negative mean potential at 100 mA/cm(2) polarization current density can.reach -1.928 V. The largest corrosion current density 19.37 mA/cm(2) of the Mg-5%Hg-5%Ga alloy appears in the Mg-5%Hg-5%Ga alloy with intergranular cutectic alpha-Mg and Mg21Ga5Hg3.