Commercial purity Mg, Mg-RE alloys ZE10A (UNS M11600), and EV31A (UNS M12310) were evaluated in the as-received condition for potential application as anode for Mg-air battery. Anodic and cathodic polarization studies were performed in 0.6 M of NaCl, 0.5 M of NaNO 3 and 0.1 M of Na 2 SO 4 . Hydrogen evolved during anodic polarization was measured at different current densities. Electrochemical impedance spectroscopy was carried out at open circuit conditions, and galvanostatic conditions. The results showed that commercial purity magnesium had higher corrosion resistance than the Mg-RE alloy specimens in all the electrolytes tested. All the specimens showed negative difference effect (NDE) where the rate of hydrogen evolution increased with increased anodic polarization. The NDE was more pronounced on ZE10A than on other materials. The results suggest that EV31A could be a potential anode material for Mg-air battery due to its better discharge capabilities. The surface layer formed on the Mg specimen showed predominantly a p-type semiconductivity with a charge carrier density in the order of 10 21 cm −3 . The Mg-RE alloys showed a dual layered surface layer with bottom n-type and top p-type characters. The p-type behavior could be associated with the formation cation vacancies due to dissolution of Mg from its lattice site, and the n-type semiconductivity could be attributed to segregation of trivalent rare earth cations at the metal/oxide interface. The enhanced NDE behavior of the Mg-RE alloys could also be attributed to the surface enrichment of Zr, and presence of Mg x RE y type secondary phases.

Several radioactive iodine isotopes are formed as fission products in the nuclear fuel, and retained within the fuel matrix by the fuel cladding as containment. During reprocessing of the used fuels by the pyroprocessing route, a significant fraction of iodine is reported to be retained in the molten salt as iodide (I -). The oxidation of Iis strongly influenced by the Cl -. When Clconcentration is in excess of I -, the iodide oxidizes to [ICl2]in two single electron steps via an [I2Cl]intermediate. The presence of chloride leads to oxidation of I3to occur at less positive potentials. Chemla effect of type 1 has been observed in the LiCl-KCl molten salt systems wherein the mobility of the K + is larger than that of Li + when the fraction of KCl is higher than 0.325 at 723 K. The Chemla effect could lead to accumulation of KCl near the cathode and adversely influence the electrolytic parameters.

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Mg-RE alloy Electron717 (ZE10A, UNS M11600) has a nominal composition of 1.2wt % Zn, 0.25wt% Zr, <0.5%Zr, 0.007wt%Mn, 0.004wt %Fe, 0.001wt%Ni and balance Mg. The alloy was investigated in three different heat-treated conditions such as (1) as received (AR) (average grain size dav = 7.90 µm), ( 2) solution treated at 525 o C for 8 hours (ST8 with dav: 26.24 µm) and ( 3) solution treated at 525 o C for 24 hours (ST24 with dav: 41.37 µm). Anodic and cathodic polarizations were carried out in three different electrolytes (pH unadjusted) such as: a) 0.6M NaCl, b) 0.5M NaNO3, and c) 0.1 M Na2SO4. The results are compared with commercial purity magnesium with an average grain size of 16 μm. The effect of grain size on the corrosion rate was observed for ZE10A alloy in the 0.1 M NaNO3 solution. Increase in the grain size increased the corrosion current density. The grain size effect diminished when polarized to high anodic potentials. Commercial purity magnesium showed lower corrosion current density than the ZE10A specimens in all the solutions tested in this study.

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