Corrosion behaviour of magnesium alloy AZ80 alloyed with Nd in simulated concrete pore solutions

Abstract

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.