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铁道科学与工程学报

JOURNAL OF RAILWAY SCIENCE AND ENGINEERING

Vol. 19    No. 3    June 2009

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Comparison of corrosion behaviors of AZ31, AZ91,
AM60 and ZK60 magnesium alloys
CHENG Ying-liang(程英亮)1, QIN Ting-wei(秦廷伟)1, WANG Hui-min(王慧敏)1, ZHANG Zhao(张 昭)2

1. College of Materials Science and Engineering, Hunan University, Changsha 410082, China;
2. Department of Chemistry, Zhejiang University, Hangzhou 310027, China

Abstract:The corrosion behaviours of four kinds of rolled magnesium alloys of AZ31, AZ91, AM60 and ZK60 were studied in 1 mol/L sodium chloride solution. The results of EIS and potentiodynamic polarization show that the corrosion resistance of the four materials is ranked as ZK60>AM60>AZ31>AZ91. The corrosion processes of the four magnesium alloys were also analyzed by SEM and energy dispersive spectroscopy(EDS). The results show that the corrosion patterns of the four alloys are localized corrosion and the galvanic couples formed by the second phase particles and the matrix are the main source of the localized corrosion of magnesium alloys. The corrosion resistance of the different magnesium alloys has direct relationship with the concentration of alloying elements and microstructure of magnesium alloys. The ratio of the β phase in AZ91 is higher than that in AZ31 and the β phase can form micro-galvanic cell with the alloy matrix, as a result, the corrosion resistance of AZ31 will be higher than AZ91. The manganese element in AM60 magnesium alloy can form the second phase particle of AlMnFe, which can reduce the Fe content in magnesium alloy matrix, purifying the microstructure of alloy, as a result, the corrosion resistance of AM60 is improved. However, due to the more noble galvanic couples of AlMnFe and matrix, the microscopic corrosion morphology of AM60 is more localized. The zirconium element in ZK60 magnesium alloy can refine grain, form stable compounds with Fe and Si, and purify the composition of alloy, which results in the good corrosion resistance of ZK60 magnesium alloy.

 

Key words: magnesium alloy; corrosion; electrochemical impedance spectrum; polarization curves

ISSN 1672-7029
CN 43-1423/U

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