Influence of aging treatments on microstructure and electrochemical properties in Mg–8.8Hg–8Ga (wt%) alloy

All precipitate morphologies in Mg–8.8%Hg–8%Ga alloy for a range of aging temperatures are investigated in detail using SEM, TEM and OM. The results show that Mg21Ga5Hg3 are the dominant precipitate in Mg–8.8%Hg–8%Ga alloy. Mg21Ga5Hg3 phase precipitate in dispersed particles. There are few papers focuses on the relationship between the aging behavior and the electrochemical and corrosion properties in Mg–8.8%Hg–8%Ga alloy. This study elaborates on the morphological evolution of Mg21Ga5Hg3 precipitates as a function of aging time and temperature and investigates the associated second phase morphology-electrochemical and corrosion response. The corrosion behavior of the Mg–8.8%Hg–8%Ga alloy is also discussed.

► Dispersed Mg21Ga5Hg3 with Ge8Pd21 tetragonal structure precipitated at 416 K. ► Larger size of the Mg21Ga5Hg3 leads to better electrochemical activation. ► A pitting corrosion in Mg alloy is ascribed to a self-catalyzed reaction. ► The activity mechanism of the Mg–Hg–Ga alloy is dissolving-precipitation of alloying elements Hg and Ga.