合金化及热处理对镁合金阳极材料组织及性能的影响

Effect of alloying and heat treatment on electrochemical behavior of Mg anode

采用熔炼铸造法制备Mg合金阳极材料,采用恒电流法和动电位极化扫描法研究合金成分和热处理对其电化学行为的影响,采用光学显微镜、扫描电镜和X射线衍射仪对不同热处理状态下显微组织和腐蚀产物进行观察和检测。结果表明:随着Hg含量的增加,固溶态试样在100mA/cm2放电电流密度下的稳定电位由-1.547V降至-1.772V,Hg对Mg阳极材料具有较强的活化作用。热处理使Mg阳极第二相Mg5Ga2沿晶界和晶内弥散析出。Mg合金阳极材料的电化学活性由大至小的顺序为铸态、96h时效态、2h时效态、固溶态,而腐蚀抗力却按此顺序依次增大,Mg合金阳极材料的腐蚀类型为全面腐蚀与点蚀共存。

Mg anode materials were prepared by melting and casting. The effects of chemical composition and heat treatment on the electrochemical corrosion behavior of Mg anode materials were investigated by potentiodynamic polarization and galvanostatic tests. The scanning electron micrographs of the secondary phase after aging treatment and the corroded surface of specimens after galvanostatic test were observed by OM, SEM and XRD. The results show that the stable potential of Mg anode materials decreases from -1.547 V to -1.772 V with the increase of Hg contents, Hg is an activator element of Mg anode materials. The MgsGa2 phase precipitates homogeneously along the grain boundary and within the grain when the Mg-Hg-Ga alloys were aged at 200℃ for 96 h. The order from big to small of the electrochemical activity of the alloys is the as-cast specimens, the specimens aged at 200℃ for 96 h, the specimens aged at 200℃ for 2 h and super-saturated solid solution, and the corrosion resistance of the alloys follows the opposite order. The corrosion of the aged Mg-Hg-Ga alloy is mainly generous attack and pitting attack.