Corrosion Mechanism of AM50 Magnesium Alloy in Simulated Acid Rain
Feng Liu, Yingwei Song, Dayong Shan and En-Hou Han
Affiliation: State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
The poor corrosion resistance of magnesium alloys is limiting their widespread applications. Some patents and
literatures have reported corrosion-resistant magnesium alloys and surface treatment techniques to improve the corrosion
resistance. However, these acknowledges are not enough for well understanding the corrosion behavior of magnesium
alloys in actual application environments. In this paper, the influence of Cl- on the corrosion rate of AM50 alloy in
simulated acid rain (SAR) was studied using electrochemical tests and scanning electronic microscopy (SEM)
observation, and then the corrosion mechanism of magnesium alloys in the acid solution was established. The results
show that Cl- can accelerate the corrosion of Mg matrix around the AlMn phases in the initial stage of corrosion. The
predominant corrosion type of the AM50 alloy is the uniform type of corrosion in SAR. The coverage fraction of
Mg(OH)2, MgH2, and the concentration of Mg+ are three key factors influencing the corrosion processes of magnesium
alloys in SAR.
Keywords: Acid solutions, Mg alloys, corrosion mechanism, negative difference effect, simulated acid rain (SAR).
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