固溶处理对Mg-6Al-5Pb-1Zn-0.3Mn阳极组织和性能的影响
来源期刊：中南大学学报(自然科学版)2012年第10期
论文作者：石凯 王日初 解立川 彭超群 金和喜 冯艳
文章页码：3785 - 3792
关键词：镁合金阳极；固溶处理；显微组织；腐蚀性能；电化学性能
Key words：magnesium alloy anode; solution treatment; microstructure; corrosion resistance; electrochemical property
摘 要：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24 h，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。
Abstract: In order to improve the workability of as-cast Mg-6Al-5Pb-1Zn-0.3Mn(mass fraction, %) anode, solution treatment was carried out. The effects of different solution time on the self-corrosion and electrochemical behavior of magnesium alloy anode were investigated by immersion tests, electrochemical impedance spectroscopy tests, galvanostatic and potentiodynamic polarization tests in 3.5% NaCl. The microstructures and the corroded surfaces of the experimental samples were observed by optical microscopy and scanning electron microscopy. The results show that the coarse β-Mg17Al12 phase is completely redissolved into the matrix and dendritic segregation almost disappears after solution at 400 ℃ for 24 h. Compared with the as-cast alloy, the corrosion resistances of the solution-treated alloys are decreased due to the disappearance of aluminium-rich areas and the discharge ability is also decreased because of the decrease of crystal defects. However, along with the extending of the solution time, the decrease of cathode β-Mg17Al12 phase can lead to an increase of the corrosion resistance and the increase of the solubility of alloying elements can lead to an increase of the discharge ability. During the discharging process, the discharge product layer easily peels off from the matrix, which maintains the discharge ability of magnesium alloy anode.
石凯，王日初，解立川，彭超群，金和喜，冯艳
(中南大学 材料科学与工程学院，湖南 长沙，410083)
摘 要：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24 h，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。
关键词：镁合金阳极；固溶处理；显微组织；腐蚀性能；电化学性能
SHI Kai, WANG Ri-chu, XIE Li-chuan, PENG Chao-qun, JIN He-xi, FENG Yan
(School of Materials Science and Engineering, Central South University, Changsha 410083, China)
Abstract:In order to improve the workability of as-cast Mg-6Al-5Pb-1Zn-0.3Mn(mass fraction, %) anode, solution treatment was carried out. The effects of different solution time on the self-corrosion and electrochemical behavior of magnesium alloy anode were investigated by immersion tests, electrochemical impedance spectroscopy tests, galvanostatic and potentiodynamic polarization tests in 3.5% NaCl. The microstructures and the corroded surfaces of the experimental samples were observed by optical microscopy and scanning electron microscopy. The results show that the coarse β-Mg17Al12 phase is completely redissolved into the matrix and dendritic segregation almost disappears after solution at 400 ℃ for 24 h. Compared with the as-cast alloy, the corrosion resistances of the solution-treated alloys are decreased due to the disappearance of aluminium-rich areas and the discharge ability is also decreased because of the decrease of crystal defects. However, along with the extending of the solution time, the decrease of cathode β-Mg17Al12 phase can lead to an increase of the corrosion resistance and the increase of the solubility of alloying elements can lead to an increase of the discharge ability. During the discharging process, the discharge product layer easily peels off from the matrix, which maintains the discharge ability of magnesium alloy anode.
Key words:magnesium alloy anode; solution treatment; microstructure; corrosion resistance; electrochemical property
