Corrosion mechanism of Mg alloys involving elongated long-period stacking ordered phase and intragranular lamellar structure

作     者：Jinshu Xie Jinghuai Zhang Zhi Zhang Zijian Yu Zhihao Xu Ru Wang Daqing Fang Xiaobo Zhang Xiaoru Zhang Ruizhi Wu Jinshu Xie;Jinghuai Zhang;Zhi Zhang;Zijian Yu;Zhihao Xu;Ru Wang;Daqing Fang;Xiaobo Zhang;Xiaoru Zhang;Ruizhi Wu

作者机构：Key Laboratory of Superlight Material and Surface TechnologyMinistry of EducationCollege of Materials Science and Chemical EngineeringHarbin Engineering UniversityHarbin 150001China Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China State Key Laboratory for Mechanical Behavior of MaterialsXi’an Jiaotong UniversityXi’an 710049China Jiangsu Key Laboratory of Advanced Structural Materials and Application TechnologyNanjing Institute of TechnologyNanjing 211167China 

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

年 卷 期：2023年第151卷第20期

页      面：190-203页

核心收录：

学科分类：08[工学] 0806[工学-冶金工程] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0703[理学-化学] 

基　　金：supported by the National Natural Science Foundation of China(Nos.51871069,52071093,and 52201137) the Opening Project of Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology(No.ASMA202205) the Student Research and Innovation Fund of the Fundamental Research Funds for the Central Universities(No.3072022GIP1004) the Beijing Municipal Natural Science Foundation(No.2202004). 

主　　题：Mg alloys Stacking faults LPSO phase SKPFM Quasi in-situ AFM Corrosion behavior Potential fluctuation 

摘      要：It is a long-term challenge to further improve the corrosion resistance while ensuring the strength of magnesium(Mg)alloys.Revealing the effect of potential fluctuation on the micro-galvanic corrosion and the subsequent film formation is important for understanding the corrosion mechanism of Mg alloys with multiple strengthening phases/structures.Here,we prepared the high-strength Mg-14.4Er-1.44Zn-0.3Zr(wt.%)alloys containing hybrid structures,i.e.,elongated long-period stacking ordered(LPSO)blocks+intragranular stacking faults(SFs)/LPSO lamellae.The Mg alloy with elongated LPSO blocks and intragranular LPSO lamellae(EZ-500 alloy)obtains good corrosion resistance(2.2 mm y^(–1)),while the Mg alloy containing elongated LPSO blocks and intragranular SFs(EZ-400 alloy)shows a significantly higher corrosion rate(6.9 mm y^(–1)).The results of scanning Kelvin probe force microscopy(SKPFM)show the elongated LPSO blocks act as cathode phase(87 mV in EZ-400 alloy),and the SFs serve as the weak anode(30 mV in EZ-400 alloy),resulting in high potential fluctuation in EZ-400 alloy.On the contrary,both elongated blocks and intragranular lamellae are cathodic LPSO phase(67–69 mV)in EZ-500 alloy,leading to a lower potential fluctuation.Quasi in-situ atomic force microscope(AFM)observation indicates that high potential fluctuation would cause strong micro-galvanic corrosion,and subsequently leads to the failure in rapid formation of corrosion film,finally forming a loose and porous film,while relatively low potential fluctuation could result in more uniform corrosion mode and facilitate the rapid formation of protective film.Therefore,we propose that it is an effective way to develop high-strength corrosionresistant Mg alloys by controlling the potential fluctuation to form a“uniform potentialstrengthening microstructure。