Influence of Mg5Ga2 compound on microstructures and electrochemical properties of Mg-5%Hg-22%Ga alloy

• Published in: Progress in natural science 2011-02, Vol.21 (1), p.73-79
• Main Authors: FENG, Yan, WANG, Ri-chu, PENG, Chao-qun, TANG, Hui-ping, LIU, Hai-yan
• Format: Article
• Language: English
• Subjects: alloys; anodic; anodic behavior; behavior; corrosion; intergranular; intergranular corrosion; Mg-Hg-Ga; Mg-Hg-Ga alloys; Mg5Ga2; Mg5Ga2 phase; phase
• ISSN: 1002-0071
• DOI: 10.1016/S1002-0071(12)60028-8

<正>The Mg-5%Hg-22%Ga（mole fraction） alloy was melted.Aging at 573-673 K for different times was carried out to ensure the fine dispersion of the Mg5Ga2 compound.Scanning electron microscopy（SEM）,X-ray diffractometry（XRD） and energy spectrum analysis（ESA） were employed to characterize the microstructures and phases of the Mg-5%Hg-22%Ga alloy.The electrochemical and corrosion behaviors of the above alloy were studied by potentiodynamic,galvanostatic and electrochemical impedance spectroscopy（EIS） measurements.The relationship between the Mg5Ga2 compound and the electrochemical properties of the Mg-5%Hg-22%Ga alloy was discussed.The results demonstrate that the heat treatment at 573-673 K for 24 h accelerates the growth of the intergranular eutectic Mg-Mg5Ga2 and the heat treatment for 200 h prompts the transition of eutectic to dispersed linear Mg phase and Mg5Ga2 matrix.This transition enhances the electrochemical activity and corrosion resistance of the Mg-5%Hg-22%Ga alloy.In the galvanostatic tests with current density of 100 mA/cm2,the most negative potential,-1.991 V, occurs in the sample aged for 200 h.The largest corrosion current density of 44.36 mA/cm2 occurs in the sample aged for 24 h.