In Situ Scanning Tunneling Microscopy Study of Grain-Dependent Corrosion on Microcrystalline Copper

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• 作者：Esther Martinez-Lombardia ; Vincent Maurice ; Linsey Lapeire ; Iris De Graeve ; Kim Verbeken ; Leo Kestens ; Philippe Marcus ; Herman Terryn
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：November 6, 2014
• 年：2014
• 卷：118
• 期：44
• 页码：25421-25428
• 全文大小：645K
• ISSN：1932-7455

文摘

In situ electrochemical scanning tunneling microscopy (ECSTM) was applied to analyze the local susceptibility to corrosion at different grains of cryogenically rolled microcrystalline copper in a HCl solution, and combined with electron backscatter diffraction (EBSD) and field emission scanning electron miscroscopy (FE-SEM) to discuss the relationship between nanometer scale corrosion resistance and crystallographic orientation. The results show that the thickness of the air-formed oxide layer is grain-dependent with the largest values exceeding locally by a factor of 2 the macroscopic value (2.8 nm) measured electrochemically. Anodic dissolution is also grain-dependent with dissolving grains observed to neighbor corrosion-resistant grains. A nearly random texture prevented an EBSD-based assignment of the crystallographic orientation of the grains observed by ECSTM. However, comparison of the etched surface morphology measured in situ by ECSTM and ex situ by FE-SEM suggested that the faster dissolving grains were oriented closer to 鉄?11鉄?/ND or in between 鉄?11鉄?/ND and 鉄?10鉄?/ND while the neighboring corrosion-resistant grains were oriented closer to 鉄?01鉄?/ND. The higher step density measured by ECSTM on the grains corroding faster despite possibly 鉄?11鉄?/ND oriented terraces confirms the role of surface defects related to misorientation on the corrosion susceptibility.