The microstructure and corrosion resistance of as-extruded Mg-6Gd-2Y- (0–1.5) Nd-0.2Zr alloys

Abstract In this study, the microstructure and corrosion resistance of Mg-6Gd-2Y-χNd-0.2Zr (χ = 0, 0.5, 1 and 1.5 wt%) alloys in extrusion condition are investigated using the correlative microscopic observations, immersion tests and electrochemical measurements. Results show that the addition of Nd can affect the grain size, crystal orientation and secondary phase of the alloys. The corrosion resistance of Mg-6Gd-2Y-χNd-0.2Zr alloys increases with the increase of Nd content from 0% to 0.5 wt%, and then decreases from 0.5 wt% to 1.5 wt%. A minor 0.5 wt% addition of Nd can improve the corrosion resistance of Mg-6Gd-2Y-0.2Zr alloy. The grain size of the four alloys is in a range from 4 μm to 7 μm and the 1.5Nd alloy with the smallest grain has the highest corrosion rate. The highest corrosion resistance of 0.5Nd alloy is attributed to the highest intensity of (0001) basal texture and the less amount of secondary phases. However, the higher fraction of secondary phase is the main reason for the highest corrosion rate of 1.5Nd alloy.