Effect of Mn on microstructure and corrosion properties of extruded Mg-1% Zn alloy

The microstructure of the extruded Mg-1Zn alloy doped with different content of manganese was analyzed by optical microscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy and X-ray diffractometry. The mass-loss immersion method and electrochemical test were used to evaluate the corrosion properties. The results show that the microstructure of the extruded Mg-1% Zn-x% Mn (mass fraction, x=0.4, 0.8, 1.2) alloys consists of alpha-Mg and alpha-Mn, the grain size of alpha-Mg decreases with increasing Mn content. Electrochemical corrosion behavior of the alloys is similar. Mn has considerable effect on the corrosion rate, the corrosion process is exacerbated by the galvanic corrosion occurred at interface between alpha-Mg and alpha-Mn. The corrosion rate increases as the Mn content increases. Mg-1% Zn-0.4% Mn alloy exhibits the best corrosion resistance between the Mg-1% Zn-x% Mn alloys