固溶处理对AP65镁合金阳极放电活性的影响

采用熔炼铸造法制备AP65镁合金阳极材料,采用扫描电镜(SEM)结合能谱分析(ESA)研究不同状态下试样的显微组织和腐蚀形貌,采用X线衍射仪(XRD)分析不同状态下试样的相结构,采用动电位极化扫描法、恒电流氧化法和交流阻抗法研究不同状态下试样在3.5%NaCl溶液中的电化学行为。研究结果表明:铸态试样在晶界处存在不连续分布的第二相Mg17Al12,该第二相能增强试样的耐蚀性,但导致试样局部腐蚀严重且放电活性较弱;经400℃固溶24 h后第二相溶解,试样的耐蚀性减小,腐蚀相对铸态试样均匀且放电活性增强。

Effect of solid solution treatment on discharge activity of AP65 magnesium alloy anode

AP65 magnesium alloy anode was prepared by melting and casting.The microstructures and corrosion morphologies of the specimens under different conditions were investigated by scanning electronic microscopy(SEM) and emission spectrum analysis(ESA),the phase structures of the specimens under different conditions were analyzed by X-ray diffraction(XRD),and the electrochemical behavior of the specimens under different conditions in 3.5% NaCl solution was studied by potentiodynamic polarization,galvanostatic oxidation test and electrochemical impedance spectroscopy.The results show that the second phase Mg17Al12 distributing discontinuously along the grain boundaries of the as-cast specimen can enhance the corrosion resistance but accelerate the local corrosion or reduce the discharge activity of AP65 anode.After solid solution treatment at 400 ℃ for 24 h,the second phase dissolves into the magnesium matrix and the corrosion resistance decreases but the corrosion develops uniformly on the specimen surface,leading to an improvement of the activity of AP65 anode.