Effect of Mg12Nd and Mg3Nd On the Corrosion Behavior of Mg-3 wt%Nd Alloy in Saline Solution

In this paper, the precipitates of the Mg-3 wt%Nd alloy in the as-cast state and after heat treatment at 540 degrees C for 12 h were investigated and related to the corrosion behavior in saline solution. For the as-cast specimen, the network and spherical beta-phases (Mg12Nd) act as the anodes relative to Mg matrix at the initial stage of immersion in saline solution. With increasing the immersion time, the intergranular corrosion caused by the preferential dissolution of the reticular beta-phase leads to the detachment of Mg fragments. For the heat-treated specimen, the plate-shaped beta(1)-phases (Mg3Nd) distributed evenly in the grain interior act as the micro-cathodes. The corrosion pits are prone to extend horizontally and connected each other, resulting in an uniform corrosion status and a relatively lower corrosion rate. This result is helpful for developing the biomedical Mg-Nd base alloys with a good degradation property by adjusting the precipitation of intermetallics.