Effect of Nd on the microstructure and corrosion behavior of Mg-Gd-Nd-Zr alloys

The corrosion behavior of Mg-12.5Gd-xNd-0.3Zr (x = 1, 2, 3 wt%) alloys were investigated by weight loss tests and electrochemical measurements in 3.5% NaCl solution. The results show that the increase of Nd content refine the grains gradually and promote the precipitates. Mg-12.5Gd-xNd-0.3Zr alloy is composed of α-Mg and Mg₅Gd and Nd₄₁Mg₅ phase, and the semi-continuous phase is formed with addition of 3% Nd. The corrosion resistance of Mg-12.5Gd-xNd-0.3Zr alloys sharply increases with the increase of Nd element by weight loss tests and the tendency is proven by means of electrochemical measurements. The corrosion resistance is improved when Nd content increases from 1% to 3% owning to the diminishing grain size and the change of distribution for second phase. The second phase play a dual effect on corrosion which depend on its distribution. (paper)