Effect of second phases on the corrosion behaviour of wrought Mg-Zn-Y-Zr alloy

The corrosion behaviour of wrought Mg-Zn-Y-Zr alloy was investigated by corrosion morphology observation and electrochemical measurement. The results indicate that the corrosion process can be divided into three stages, corresponding to three types of corrosion features. At the initial stage, corrosion occurred surrounding the second phases, which was driven by galvanic couple effect; at the middle stage, filiform corrosion was found in the central regions of α Mg matrix; at the final stage, pitting corrosion presented around the second phases. The second phases have a great effect on the corrosion process of Mg-Zn-Y-Zr alloy.