Adjusting the microstructure through the deformation process is one of the ways to improve the properties of Mg alloys. Most studies have focused on the influence of the microstructure after deformation treatment on the mechanical properties of Mg alloys. In this paper, extruded and forged Mg-Gd-Y-Nd-Zr alloys were selected to investigate the corrosion performance of two deformed magnesium alloys immersed in 0.6 M NaCl solution using a hydrogen evolution test, a weight loss test, an immersion experiment, and an electrochemical test. The results showed that WE43 alloys undergoing different deformation treatments presented different microstructures, which led to different corrosion behaviors and corrosion resistance. The extruded WE43 alloy showed uniform corrosion, while the forged WE43 alloy suffered severe local galvanic corrosion. Meanwhile, the corrosion rate of the forged WE43 alloy was about four times faster than that of the extruded WE43 alloy.
As a kind of potential biomedical material, Mg–Ca alloy has attracted much attention. However, the role of Ca-containing intermetallics in microgalvanic corrosion is still controversial. In 0.6 mol/L NaCl and Na2SO4 solutions, the microgalvanic corrosion behavior of the second phase and Mg matrix of Mg–Ca and Mg–Al–Ca alloys was examined. It was confirmed that the Mg2Ca phase acts as a microanode in microgalvanic corrosion in both NaCl and Na2SO4 solutions, with the Mg matrix acting as the cathode and the Al2Ca phase acting as the microcathode to accelerate corrosion of the adjacent Mg matrix. It was also found that Cl− and SO42− have different sensibilities to microgalvanic corrosion.
The corrosion behavior and corrosion resistance of WE43 and AZ80 immersed in NaCl and Na2SO4 solutions were investigated, respectively. Two alloys were immersed in 0.6 M NaCl and Na2SO4 solution to observe the corrosion morphologies. Hydrogen evolution and weight loss experiments were conducted to obtain the corrosion rates. Electrochemical tests were used to characterized detailed corrosion situation. The results show that, when immersed in Na2SO4 solution, WE43 alloy shows a unique micro-galvanic corrosion behavior. On the other hand, the corrosion rate of WE43 in Na2SO4 solution is much faster than that in NaCl solution, which is the direct opposite of AZ80 and most magnesium alloys. The protection of the surface film maybe the key factor to the unexpected phenomena.