The corrosion behaviour of Nd alloyed magnesium alloy AZ80 in three simulated concrete pore solutions (SCPs) was studied using corrosion immersion tests and electrochemical tests. The study investigated the effects of the composition and pH of the SCPs on the corrosion properties of AZ80 and AZ80-1.0Nd using aluminum alloy AA6061 as a reference. The SCP1, SCP2, and SCP3 solutions were the simulated concrete pore solutions with different carbonation stages at pH 13.5, 12.5, and 9.7 respectively. The corrosion mainly in the form of localized corrosion, developed significantly along the transverse direction, and less in the vertical direction. AZ80 and AZ80-1.0Nd exhibited the best corrosion resistance in the SCP2 solution, which was attributed to the formation of a dense protective film on the surface. The corrosion in the high alkalinity SCP1 solution was first enhanced within 12 h and then somewhat decreased within 72 h attributed to the destruction and re-formation of the surface film. AA6061 corroded severely in the SCP1 solution and suffered significantly less corrosion in the SCP2 and SCP3 solutions. Nd alloying contributed to the reduced corrosion rates of AZ80 in the simulated concrete pore solutions, attributed to changes in the microstructure and electrochemical properties.
Zou Qi,Le Qichi,Chen Xingrui,Ban Chunyan,Jia Yonghui,Guo Ruizhen,Wang An
This work investigated the corrosion resistance of AZ80 (Mg-8Al-0.5Zn alloy) with different Nd contents in alkaline solution by the mass loss test, electrochemical test, scanning electron microscope, energy spectrum analysis, and x-ray diffraction. To remove the influence of the Mg 17 Al 12 phase, alloys were heat treated at 410°C for 10 h. Results revealed that Al 2 Nd and AlMnNd phases mainly exist in the alloy. The corrosion rate of the alloy increased when the Nd content was < 0.4 wt.% because the Al 2 Nd phase formed galvanic corrosion with the Mg matrix. With the increase of Nd content, AlMnNd phase appeared in the alloys, which decomposed during the corrosion process and formed a good protective film to reduce the corrosion rate.
The corrosion behavior and corrosion resistance of WE43 and AZ80 immersed in NaCl and Na2SO4solutions were investigated, respectively. Two alloys were immersed in 0.6 M NaCl and Na2SO4solution 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 Na2SO4solution, WE43 alloy shows a unique micro-galvanic corrosion behavior. On the other hand, the corrosion rate of WE43 in Na2SO4solution 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.Keywords:magnesium alloys;rare earth elements;micro-galvanic corrosion;surface film;corrosion resistance
危险品化学品经营许可证（带存储）