Aging behaviour and electrochemical properties in Mg–4.8Hg–8Ga (wt.%) alloy

All precipitate morphologies in Mg–4.8%Hg–8%Ga alloy for a range of aging temperatures are investigated in detail using TEM and OM. The results show that Mg5Ga2 and Mg21Ga5Hg3 are the dominant precipitate in Mg–4.8%Hg–8%Ga alloy. Mg5Ga2 phases precipitate in slab and massive morphologies. Mg21Ga5Hg3 phases precipitate in dispersed particles. There have few papers focused on the relationship between the aging behaviour and the electrochemical and corrosion properties in Mg–4.8%Hg–8%Ga alloy. This study elaborates on the morphological evolution of Mg5Ga2 and Mg21Ga5Hg3 precipitates as a function of aging time and temperature and investigates the associated second phase morphology-electrochemical and corrosion response.

Research highlights
► Dispersed Mg21Ga5Hg3 with Ge8Pd21 tetragonal structure precipitated at 423 K
► Slab and massive Mg5Ga2 with D8g orthogonal structure precipitated at 439 K
► Slab and massive Mg5Ga2 dissolved in Mg matrix at 506 K
► The best anode for sea water battery is Mg–4.8%Hg–8%Ga alloy aged at 473 K for 8 h