The effect of rare earth additions on the electrochemical properties of Mg-5Al-based alloys

The corrosion properties of four Mg-5Al-based alloys with rare earth alloying elements (calcium, misch-metal and strontium) in a 0.01 M alkaline NaCl solution were examined using electrochemical tests and surface analyses. The electrochemical tests indicated that the addition of 1% rare earth improved the pitting potential, film formation and charge transfer resistance of the Mg-5Al specimens. Moreover, the addition of 1Sr produced the best corrosion resistance due to the continuous precipitation of Mg/Al-rare earth compounds as a corrosion barrier.