Electrochemical behavior of Mg-Li, Mg-Li-Al and Mg-Li-Al-Ce in sodium chloride solution

Mg-Li, Mg-Li-Al and Mg-Li-Al-Ce alloys were prepared and their electrochemical behavior in 0.7 M NaCl solutions was investigated by means of potentiodynamic polarization, potentiostatic current-time and electrochemical impedance spectroscopy measurements as well as by scanning electron microscopy examination. The effect of gallium oxide as an electrolyte additive on the potentiostatic discharge performance of these magnesium alloys was studied. The discharge activities and utilization efficiencies of these alloys increase in the order: Mg-Li < Mg-Li-Al < Mg-Li-Al-Ce, both in the absence and presence of Ga2O3. These alloys are more active than commercial magnesium alloy AZ31. The addition of Ga2O3 into NaCl electrolyte solution improved the discharging currents of the alloys by more than 4%, and enhanced the utilization efficiencies of the alloys by more than 6%. It also shortened the transition time for the discharge current to reach to a steady value. Electrochemical impedance spectroscopy measurements showed that the polarization resistance of the alloys decreases in the following order: Mg-Li > Mg-Li-Al > Mg-Li-Al-Ce. Mg-Li-Al-Ce exhibited the best performance in term of activity, utilization efficiency and activation time. (C) 2007 Elsevier B.V. All rights reserved.