Microsegregation and the Tendency for Pitting Corrosion in High-Purity Aluminum

Bond, A. P.; Bolling, G. F.; Domian, H.A.; Biloni, H.

doi:10.1149/1.2424117

Cited by 68 publications

(25 citation statements)

References 8 publications

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“…As is reported in the literature, this is especially the case when the anodic film has deficiently been sealed in order to sustain its ability to anchor organic coatings [31]. The rates of both anodic and cathodic reactions are higher at the flaws and the observed polarisation curves may largely be related to these localised flaws [32]. Al-alloys with flawed passive films, present corrosion potential values equal (or nearly equal) to pitting potential values.…”

Section: Al2024 T3mentioning

confidence: 91%

Enhanced bonded aircraft repair using nano-modified adhesives

et al. 2012

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Section: Al2024 T3mentioning

confidence: 91%

Enhanced bonded aircraft repair using nano-modified adhesives

et al. 2012

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“…Bond et al 2 showed that pits may initiate near microsegregated iron, copper, and silicon impurities in high purity aluminum. It is possible that elevated near-surface concentrations of these impurities are present after dissolution in NaOH, since concentrations of elements less reactive than the metal are typically enhanced by dissolution.…”

Section: Infroductjonmentioning

confidence: 99%

Development of Surface Impurity Segregation during Dissolution of Aluminum

Hebert

1996

J. Electrochem. Soc.

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Caustic dissolution, when used as a pretreatment for etching of aluminum in chloride solutions, is observed to increase the rate of pit nucleation. Rutherford backscattering spectrometry (RBS) and Auger electron spectroscopy were used to measure the composition in the near-surface region of 99.98% purity aluminum after dissolution in 1 N NaOH at room temperature. During dissolution, concentrations of impurities such as Fe, Cu, and Ga were found to accumulate continuously within a layer less than about 10 nm thick adjacent to the surface, because they dissolved more slowly than did aluminum. Impurity concentrations on the order of 1 atom percent (a/o) in this layer, much higher than equilbrium values, were found after 40 min dissolution. It is argued that the large impurity concentrations are consistent with a highly defective region in the metal near the metal/oxide interface, which has been detected using positron annihilation measurements. Dissolution produced a scalloped surface topography with typically 30 nm high ridges separated by 130 nm. A simulation of RBS measurements based on scattering from spherical particles was developed to test for the possibility of preferential impurity segregation to ridges. No such segregation was detected, suggesting that this is not the reason for the strong tendency for pit nucleation to occur on ridges, as has been observed previously. 5. K. Shimizu, G. E. Thompson, G. C. Wood, and Y Xu, Thin Solid Films, 88, 255 (1982 13. P. Skeldon, K. Shimizu, G. E. Thompson, and G. C. Wood, Thin Solid Films, 123, 127 (1985).14. P. Skeldon, K. Shimizu, G. E. Thompson, and G. C. Wood, Surf. Interface Anal., 5, 247 (1983). 15. G. Amsel, C. Cherki, G. Feuillade, and J. P. Nadai, J.Phys. Chem. Solids, 30, 2117Solids, 30, (1961 16. K. Shimizu, P. Skeldon, G. E. Thompson, and G. C. Wood, Surf. Interface Anal., 4, 208 (1981 Acta, 20, 663 (1975). 42. J. J. Randall, W. J. Bernard, and R. R. Wilkinson, ibid., 10, 183 (1965). Development of Surface Impurity Segregation during Dissolution of Aluminum Xiaolin Wu and Kurt HebertDepartment of Chemical Engineering, Iowa State University, Ames, Iowa 50011, USA ABSTRACT Caustic dissolution, when used as a pretreatment for etching of aluminum in chloride solutions, is observed to increase the rate of pit nucleation. Rutherford backscattering spectrometry (EBS) and Auger electron spectroscopy were used to measure the composition in the near-surface region of 99.98% purity aluminum after dissolution in 1 N NaOH at room temperature. During dissolution, concentrations of impurities such as Fe, Cu, and Ga were found to accumulate continuously within a layer less than about 10 nm thick adjacent to the surface, because they dissolved more slowly than did aluminum. Impurity concentrations on the order of 1 atom percent (a/o) in this layer, much higher than equilbrium values, were found after 40 mm dissolution. It is argued that the large impurity concentrations are consistent with a highly defective region in the metal near the metal/oxide interface...

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“…[3][4][5][6] Bulk concentrations of certain impurities ͑e.g., Cu and Pb͒ are carefully controlled during foil processing. 5 Apart from the surface concentrations of impurities, the grain size and microstructure of the aluminum foil ͑especially the ''cubicity,'' i.e., the proportion of surface grains having ͑100͒ orientation͒ influence the etch morphology, as does the uniformity of the surface oxide layer.…”

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Atomic Force Microscopy Study of Anodic Etching of Aluminum: Etching Morphology Development and Caustic Pretreatment

Martin

Hebert

2001

J. Electrochem. Soc.

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Atomic force microscopy ͑AFM͒ was used to investigate the topographic characteristics of pitting sites during anodic galvanostatic etching of high-purity aluminum foils in hot baths containing HCl and H 2 SO 4 . Pit sites near pre-existing ridges formed by rolling are preferred, and the distribution of sites depends on the foil fabrication process. Etch tunnels are found only within shallow pits formed by surface dissolution, which may be a prerequisite for tunnel formation. Pit sites are more numerous and evenly distributed after pretreatment of foils by immersion in 1 N NaOH. AFM imaging during acid dissolution of NaOH treated foils reveal submicrometer cavities formed as a result of NaOH treatment. Some cavities appear to form near oxide particles or inclusions. It is argued that these cavities are subsurface voids exposed by uniform dissolution in the acid. If the void surface is oxide-free, they may dissolve as pits when exposed by the shallow surface dissolution shown to take place in the etchant bath.

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Microsegregation and the Tendency for Pitting Corrosion in High-Purity Aluminum

Cited by 68 publications

References 8 publications

Enhanced bonded aircraft repair using nano-modified adhesives

Enhanced bonded aircraft repair using nano-modified adhesives

Development of Surface Impurity Segregation during Dissolution of Aluminum

Atomic Force Microscopy Study of Anodic Etching of Aluminum: Etching Morphology Development and Caustic Pretreatment

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