Exfoliation corrosion of extruded Mg-Li-Ca alloy

作     者：Zi-You Ding Lan-Yue Cui Rong-Chang Zeng Yan-Bin Zhao Shao-Kang Guan Dao-Kui Xu Cun-Guo Lin 

作者机构：College of Materials Science and Engineering Shandong University of Science and Technology Qingdao 266590 China School of Materials Science and Engineering Zhengzhou University Zhengzhou 450002 China CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Science and Technology on Marine Corrosion and Protection Laboratory Qingdao 266071 China Qingdao Branch of Luoyang Ship Material Research Institute Qingdao 266101 China 

出 版 物：《Journal of Materials Science & Technology》 (材料科学技术（英文版）)

年 卷 期：2018年第34卷第9期

页      面：1550-1557页

核心收录：

学科分类：08[工学] 

基　　金：supported by the National Natural Science Foundation of China (No. 51571134) the SDUST Research Fund (No. 2014TDJH104) 

主　　题：Magnesium-lithium alloy Exfoliation corrosion Intermetallic compound Extrusion Microstructure 

摘      要：Exfoliation on as-extruded Mg-1 Li-1 Ca magnesium alloy was investigated after an immersion in 3.5 wt%NaCl aqueous solution for 90, 120 and 150 days through optical microscope, digital camera, scanning electron microscope, electrochemical workstation, scanning Kalvin probe, X-ray diffraction and Fourier transform infrared spectroscope. The results demonstrated that exfoliation corrosion occurred on extruded Mg-1 Li-1 Ca alloy due to elongated microstructure parallel to surface, and delamination of lamellar structure resulted from galvanic effect and wedge effect. Skin layer with fine grains exhibited better corrosion resistance, whereas the interior with coarse grains and the intermetallic compound,Mg2 Ca particles existing in a fibrous structure, dispersed along grain boundaries and extrusion direction in a line. Furthermore, galvanic effect between Mg2 Ca particles and their neighboring a-Mg matrix facilitated dissolution of Mg2 Ca particles and a-Mg matrix; wedge effect was caused by formation of corrosion products. Exfoliation corrosion of extruded Mg-Li-Ca alloys might be a synergic effect of pitting corrosion,filiform corrosion, intergranular corrosion and stress corrosion. Finally, exfoliation corrosion mechanism was proposed.