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Role of trace additions of Ca and Sn in improving the corrosion resistance of Mg-3Al-1Zn alloy

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International Journal of Minerals,Metallurgy and Materials 2022年第8期29卷 1559-1569页

作者： Panpan Wang Haitao Jiang Yujiao Wang Yun Zhang Shiwei Tian Yefei Zhang Zhiming Cao Institute of Engineering Technology University of Science and Technology BeijingBeijing 100086China School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China

The limited wide applicability of commercial Mg alloys is mainly attributed to the poor corrosion resistance.Addition of alloying elements is the simplest and effective method to improve the corrosion properties.Based on the low-cost alloy composition design,the corro-sion behavior of commercial Mg-3Al-1Zn(AZ31)alloy bearing minor Ca or Sn element was characterized by scanning Kelvin probe force microscopy,hydrogen evolution,electrochemical measurements,and corrosion morphology analysis.Results revealed that the potential differ-ence of Al_(2)Ca/α-Mg and Mg_(2)Sn/α-Mg was(230±19)mV and(80±6)mV,respectively,much lower than that of Al_(8)Mn_(5)/α-Mg(430±31)mV in AZ31 alloy,which illustrated that AZ31-0.2Sn alloy performed the best corrosion resistance,followed by AZ31-0.2Ca,while AZ31 al-loy exhibited the worst corrosion resistance.Moreover,Sn dissolved into matrix obviously increased the potential ofα-Mg and participated in the formation of dense SnO_(2) film at the interface of matrix,while Ca element was enriched in the corrosion product layer,resulting in the cor-rosion product layer of AZ31-0.2Ca/Sn alloys more compact,stable,and protective than AZ31 alloy.Therefore,AZ31 alloy bearing 0.2wt%Ca or Sn element exhibited excellent balanced properties,which is potential to be applied in commercial more comprehensively.

关键词： AZ31 Mg alloy micro-galvanic corrosion alloying addition volta potential precipitates

Initial micro-galvanic corrosion behavior between Mg_(2)Ca and α-Mg via quasi-in situ SEM approach and first-principles calculation

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Journal of Magnesium and Alloys 2023年第3期11卷 958-965页

作者： Chen Xu Jianfeng Wang Chen Chen Chao Wang Yufeng Sun Shijie Zhu Shaokang Guan School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China

The initial micro-galvanic corrosion behavior of Mg-30wt%Ca alloy only containing Mg_(2)Ca andα-Mg was studied by immersion testing in a 0.9%Na Cl solution at 37°C.The quasi-in situ SEM and TEM results show that Mg_(2)Ca corroded easier thanα-Mg,indicating that Mg_(2)Ca acted as an anode.The work function(Φ)for Mg_(2)Ca calculated by first-principles is significantly lower compared to that forα-Mg.The volta potential measured by a scanning Kelvin probe force microscope reveals that the Mg_(2)Ca had a relatively low volta potential(ψ)value.The lowerΦandψvalues for Mg_(2)Ca indicate a lower electrochemical nobility,which is consistent with the experimental phenomenon.

关键词： Magnesium alloy Quasi-in situ SEM Galvanic corrosion First-principles calculations Work function volta potential

Improving corrosion resistance of Zn-5Al(wt%)alloy by microalloying with samarium

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Journal of Rare Earths 2023年第10期41卷 1636-1644,I0006页

作者： Xiaochao Zhou Wei Shi Song Xiang College of Materials and Metallurgy Guizhou UniversityGuiyang550025China Key Laboratory for Mechanical Behavior and Microstructure of Materials of Guizhou Province Guiyang550025China National&Local Joint Engineering Laboratory for High-Performance Metal Structure Material and Advanced Manufacturing Technology Guiyang550025China

The role of the rare earth element Sm in as-cast Zn-5AI alloy was studied in this work.A three times higher improvement than the control group on corrosion resistance was found with rare earth Sm adding(0.15 wt%).By using an electron prove micro analyzer(EPMA),focused ion beam(FIB)and scanning Kelvin probe force microscopy(SKPFM)techniques,two main mechanisms of the premium performance of the Sm adding were revealed.One was that the non-uniform nucleation and component undercooling induced by Sm adding,reduced theα-AI layer spacing thus improved the covering efficiency of the Al_(2)O_(3)film.The other was that the dissolved Sm in the Zn/Al eutectic structure modulated the electron work function thus induced the attenuation of volta potential discrepancy.The experimental results show that when the addition of Sm is 0.15 wt%,the minimum volta potential difference betweenα-AI andη-Zn phases is achieved,and excessive or deficient Sm addition will increase the volta potential difference.

关键词： Zn-5Al Sm Rare earth elements SKPFM volta potential