On the in-situ aqueous stability of an Mg-Li-(Al-Y-Zr) alloy: Role of Li

The aqueous stability of a corrosion resistant Mg-Li(-Al-Y-Zr)-alloy was investigated by combining in-situ confocal Raman Microscopy, Atomic Emission SpectroElectroChemistry, ex-situ Photoluminiscence Spectroscopy, Auger Electron Spectroscopy and Glow Discharge Optical Emission Spectroscopy. Li and Mg dissolved from visually intact anodic areas, leaving a Li-depleted metallic layer under approximately 100 nm thick Li-doped MgO. The transformation MgO -> Mg(OH)(2) was inhibited. Li-2[Al-2(OH)(6)](2)center dot CO3 center dot nH(2)O, LiAlO2, Y2O3 and Mg(OH)(2) accumulated locally around active cathodic sites. New corrosion mechanism is proposed, which associates the improved corrosion resistance of Mg-Li alloys with an enhanced chemical stability and modified catalytic activity of MgO in presence of Li+.