Localized Corrosion Behavior of Al-Si-Mg Alloys Used for Fabrication of Aluminum Matrix Composites
Localized Corrosion Behavior of Al-Si-Mg Alloys Used for Fabrication of Aluminum Matrix Composites
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DOI：
10.1007/s11665-013-0674-0
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发表时间：
2013-08
影响因子：
2.3
通讯作者：
M. Pech-Canul;R. Giridharagopal;M. Pech‐Canul;E. E. Coral-Escobar-E.
中科院分区：
文献类型：
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作者：
M. Pech-Canul;R. Giridharagopal;M. Pech‐Canul;E. E. Coral-Escobar-E.
用SEM/EDAX、常规电化学技术和扫描开尔文探针力显微镜（SKPFM）研究了Si/Mg摩尔比为0.12和0.49的两种定制合金在中性充气氯化物溶液中的微观结构和局部腐蚀行为之间的关系。按此顺序，在第一合金中鉴定出Al 3Fe、Al 3 Mg 2和Mg 2Si金属间化合物，在第二合金中鉴定出Al（FeMn）Si和Mg 2Si颗粒。阳极极化曲线和腐蚀形貌表明，Si/Mg摩尔比越高，合金的耐蚀性越好，钝化膜的耐蚀性越好。这两种合金在充气0.1 M NaCl溶液中的腐蚀过程是本地化周围的富铁金属间化合物。它们充当局部阴极，并使这些颗粒周围的铝基质溶解。Mg_2Si和Al_3Mg_2表现出阳极行为。SKPFM已成功地用于绘制主要金属间化合物的伏打电位分布。局部腐蚀行为与富铁金属间化合物和基体之间的大伏特电位差相关。在浸入氯化物溶液中之后，这样的伏特电位差减小。
The relationship between microstructure and localized corrosion behavior in neutral aerated chloride solutions was investigated with SEM/EDAX, conventional electrochemical techniques, and with scanning Kelvin probe force microscopy (SKPFM) for two custom-made alloys with Si/Mg molar ratios of 0.12 and 0.49. In this order, Al3Fe, Al3Mg2, and Mg2Si intermetallics were identified in the first alloy and Al(FeMn)Si and Mg2Si particles in the second one. Anodic polarization curves and corrosion morphology showed that the alloy with higher Si/Mg molar ratio exhibited a better corrosion performance and evidence was shown that it had a more corrosion-resistant passive film. The corrosion process for both alloys in aerated 0.1 M NaCl solutions was localized around the Fe-rich intermetallics. They acted as local cathodes and produced dissolution of the aluminum matrix surrounding such particles. Mg2Si and Al3Mg2exhibited anodic behavior. SKPFM was successfully used to map the Volta potential distribution of main intermetallics. The localized corrosion behavior was correlated with a large Volta potential difference between the Fe-rich intermetallics and the matrix. After immersion in the chloride solution, such Volta potential difference decreased.