Influence of heat treatment on microstructure and electrochemical properties of Mg-5Hg-1Ga alloy

A Mg-5Hg-1Ga(mass%) alloy was prepared by melting and casting. The microstruc- ture and electrochemical properties of the alloy were investigated by SEM, XRD and electrochem- ical methods. The results indicate that: with the aging time increasing from 15 min to 200 h at 400°C, the shape of the second phase in Mg-5Hg-1Ga alloy changes from eutectic-like existed in grain boundaries to block-like structures dispersed in grains, correspondingly, the corrosion current density decreases from 70.92 mA/cm 2 to 2.34 mA/cm 2, the mean potential decreases from -1.916 V to -1.989 V, the properties of electrochemical activity and corrosion resistance of the alloy are improved remarkaly. The activation mechanism of the magneium alloy induced y addition of Hg and Ga was put forward. Magnesium atoms diffuse through the liquid Hg and Ga to form magnesium amalgam and undergo severe oxidation at the electrolyte interface.