Effects of Zn on microstructure of an extruded Mg-RE-Mn alloy and its corrosion behavior in3.5%NaCl solution were investigated by means of scanning electron microscope（SEM）

X-ray diffractometer（XRD）

electrochemical test and chemical immersion methods.The results show that with Zn addition

secondary phase MgZn2、Mg2Zn11are generated

and the grain size in the alloys is obviously refined.Zn can improve the anti-corrosion property of the alloy by shifting the pitting potential to a positive value to some extent.With 1.5% Zn content

the grain size is decreased remarkably

and the microstructure becomes homogeneous

meanwhile

the average corrosion rate of the alloy is only 1.180mm/a.When Zn content is 3.0%

the precipitates are increased with the trend of coarsening and segregation.So a galvanic corrosion which can be formed for theα-Mg as an anode and the second phase as a cathode accelerates the corrosion of the alloy

resulting in the average corrosion rate of the alloy of 2.419mm/a.