Impact of rare earth elements on micro-galvanic corrosion in magnesium alloys: A comparative study of Mg-Nd and Mg-Y binary alloys

The corrosion behavior of Mg-7Nd and Mg-10Y binary alloys were investigated through scanning electron microscope observation, hydrogen evolution, weight loss experiment and electrochemical test. It was found that the corrosion rates of two alloys are mainly influenced by the micro-galvanic corrosion between the second phase and α-Mg matrix, and the second phases (Mg12Nd and Mg24Y5) have a higher activity than α-Mg matrix and act as an anode to corrode preferentially during the micro-galvanic corrosion process. Mg-7Nd alloy has a faster corrosion rate than Mg-10Y alloy due to the fact that it contains more second phase and the second phase containing Nd elements is more reactive. The different distribution of rare earth elements in the alloy can lead to different corrosion morphology.