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为了改善铸态Mg-6Al-5Pb-1Zn-0.3Mn(质量分数,%)阳极的加工性能,对其进行固溶退火处理。采用浸泡法、恒电流和动电位极化扫描法及电化学阻抗法,研究不同固溶时间对其在3.5%(质量分数)NaCl中自腐蚀和电化学行为的影响;采用光学显微镜、扫描电镜对其显微组织和腐蚀形貌进行观察。研究结果表明:经400℃固溶24h,粗大的β-Mg17Al12相完全回溶于基体中,枝晶偏析基本消除;与铸态合金相比,晶界附近富Al区的消失使得固溶态合金耐蚀性能降低,晶体缺陷的减少使得放电性能变差;随着固溶时间延长,阴极β-Mg17Al12相的减少使得合金耐蚀性能提高,合金元素固溶度的增大使得合金放电性能提高;在放电过程中,放电产物层不断脱落,维持了镁合金阳极的放电活性。
In order to improve the processing performance of as-cast Mg-6Al-5Pb-1Zn-0.3Mn (mass fraction,%) anode, it was solution annealed. The effect of different solution time on the corrosion and electrochemical behavior of 3.5% (mass fraction) NaCl was investigated by immersion method, galvanostatic and potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) The microstructure and corrosion morphology were observed. The results show that after the solution at 400 ℃ for 24h, the coarse β-Mg17Al12 phase is completely dissolved in the matrix, and the dendritic segregation is basically eliminated. Compared with the as-cast alloy, the disappearance of the Al-rich region near the grain boundary makes the solid solution alloy With the increase of solution time, the decrease of cathodic β-Mg17Al12 phase leads to the increase of corrosion resistance of the alloy, and the increase of the solid solubility of the alloying elements improves the discharge performance of the alloy. During the discharge process, the discharge product layer continuously sheds, maintaining the discharge activity of the magnesium alloy anode.