Xu Shiyuan, Liu Chuming, Gao Yonghao, Jiang Shunong, Wan Yingchun, Chen Zhiyong
School of Materials Science and Engineering, Central South University, Changsha 410083, China.
Light Alloy Research Institute, Central South University, Changsha 410083, China.
Materials (Basel). 2023 Jan 9;16(2):640. doi: 10.3390/ma16020640.
In this paper, the influence of long-period stacked ordered (LPSO) phases on the electrochemical impedance spectroscopy (EIS) of a Mg-Gd-Y-Zn-Zr-Ag alloy in 0.9 wt.% NaCl was investigated. The Mg-6Gd-3Y-1Zn-0.5Zr-0.3Ag (wt.%) alloy samples with and without LPSO phases in the grain interior (HOMO and LPSO, respectively) were prepared using different heat treatments. The EIS results showed that both the HOMO and LPSO samples' Nyquist diagrams contained two inductive loops. However, in the Nyquist plots of the LPSO samples, the inductive loops at 1.71-0.67 Hz appeared in the first quadrant rather than the fourth quadrant. Analysis of the fitting parameters illustrated that the abnormal shape of the inductive loops is related to greater values of the surface film capacitance and double layer capacitance in the LPSO samples. Further investigations through corrosion morphology observation indicated that the greater values of and in the LPSO samples resulted from the existence of intragranular LPSO phases that created more film-free areas. The above results show that a better understanding of the relationship between the inductive impedance and corrosion morphology of a Mg-6Gd-3Y-1Zn-0.5Zr-0.3Ag alloy in 0.9 wt.% NaCl solution was attained.
本文研究了长周期有序堆积（LPSO）相在0.9 wt.% NaCl溶液中对Mg-Gd-Y-Zn-Zr-Ag合金电化学阻抗谱（EIS）的影响。采用不同的热处理方法制备了晶粒内部有无LPSO相的Mg-6Gd-3Y-1Zn-0.5Zr-0.3Ag（wt.%）合金样品（分别为HOMO和LPSO）。EIS结果表明，HOMO和LPSO样品的奈奎斯特图均包含两个感应环。然而，在LPSO样品的奈奎斯特图中，1.71-0.67 Hz处的感应环出现在第一象限而非第四象限。对拟合参数的分析表明，感应环的异常形状与LPSO样品中更大的表面膜电容和双层电容值有关。通过腐蚀形貌观察的进一步研究表明，LPSO样品中更大的 和 值是由于晶内LPSO相的存在产生了更多无膜区域。上述结果表明，对Mg-6Gd-3Y-1Zn-0.5Zr-0.3Ag合金在0.9 wt.% NaCl溶液中的感应阻抗与腐蚀形貌之间的关系有了更好的理解。
