Pitting corrosion of a Rare Earth Mg alloy GW93  

作　　者：Yingwei Song Dayong Shan En-Hou Han 

机构地区：[1]Key Laboratory of Nuclear Materials and Safety Assessment,Institute of Metal Research,Chinese Academy of Sciences

出　　处：《Journal of Materials Science & Technology》2017年第9期954-960,共7页材料科学技术（英文版）

基　　金：supported by the National Natural Science Foundation of China (No. 51471174);the National Key Basic Research Program of China (No. 2013CB632205);the National Key Research and Development Program of China (No. 2016 YFB0301105)

摘　　要：Pitting corrosion of magnesium(Mg) alloys is greatly associated with their microstructure, especially second phases. The second phases in traditional Mg alloys such as AZ91 are electrochemically nobler than Mg matrix, while the second phases in Rare earth(RE) Mg alloy GW93 are more active than Mg matrix. As a result, the pitting corrosion mechanism of Mg alloy GW93 is different from the traditional ones. This paper aims to clarify the pitting corrosion mechanism of Mg alloy GW93 through the studies of Volta potential by Scanning Kelvin Probe Force Microscopy(SKPFM), corrosion morphology by Scanning Electron Microscope(SEM), and corrosion resistance by electrochemical tests. Results reveal that the pitting corrosion of GW93 includes three stages, first, dissolution of the second phases, followed by corrosion of Mg matrix adjacent to the dissolved second phases, and finally, propagation of corrosion pits along the depth direction of the dissolved second phases. Anodic second phases and enrichment of Clin the thick corrosion product films dominate the propagation of pitting corrosion.Pitting corrosion of magnesium(Mg) alloys is greatly associated with their microstructure, especially second phases. The second phases in traditional Mg alloys such as AZ91 are electrochemically nobler than Mg matrix, while the second phases in Rare earth(RE) Mg alloy GW93 are more active than Mg matrix. As a result, the pitting corrosion mechanism of Mg alloy GW93 is different from the traditional ones. This paper aims to clarify the pitting corrosion mechanism of Mg alloy GW93 through the studies of Volta potential by Scanning Kelvin Probe Force Microscopy(SKPFM), corrosion morphology by Scanning Electron Microscope(SEM), and corrosion resistance by electrochemical tests. Results reveal that the pitting corrosion of GW93 includes three stages, first, dissolution of the second phases, followed by corrosion of Mg matrix adjacent to the dissolved second phases, and finally, propagation of corrosion pits along the depth direction of the dissolved second phases. Anodic second phases and enrichment of Clin the thick corrosion product films dominate the propagation of pitting corrosion.

关 键 词：Mg alloys Pitting corrosion Second phases Oxide films 

分 类 号：TG178[金属学及工艺—金属表面处理]