Effect of 0.45 wt.% Nd Addition on the Corrosion Resistance of Extruded Mg-6Al-3Sn-2Zn Alloy

The effect of Nd microalloying on the microstructure and corrosion behavior of extruded Mg-6Al-3Sn-2Zn (ATZ632) alloys was investigated. The addition of Nd (0.45 wt.%) into the ATZ632 alloy resulted in the formation of a NdZn1.66Al2.34 phase with a relatively low Volta potential of 68 similar to 78 mV. The polarization resistance of this alloy was calculated to be 564.33 ohm cm(2), which is approximately 7.7 times slower than that of the ATZ632 alloy. The main factors for improving the corrosion resistance of the extruded ATZ632 alloy with 0.45 wt.% Nd addition are: (1) the Nd2O3 prevention of Cl- from passing through the corrosion film; (2) the formation of denser and more uniform corrosion films; and (3) the grain refinement and wakening of the (0001) base-plane texture.