Effect of grain orientation on the morphology, dielectric breakdown and optical behaviour of anodic film formed on Al–2wt%Cu binary alloy

Zhou, Xiaorong; Thompson, G.E.; Skeldon, P.

doi:10.1016/j.electacta.2008.03.034

Cited by 24 publications

(7 citation statements)

References 20 publications

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“…Compared with (110) and (111) oriented crystals, the anodizing film on (100) oriented crystal had a lower porosity, and the nanopores seemed more regular. These phenomena were consistent with previous publications [8,9] . Fig.9 showed the relationship between the surface brightness and porosity of anodized single crystals with different orientations.…”

Section: Characterization Of Anodizing Film In Single Crystals With Dsupporting

confidence: 94%

Formation Mechanism of Strip Defects in Anodizing AA5252 Aluminium Alloy Sheets

et al. 2020

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Processed by sulfuric acid anodizing, several unexpected strip defects exhibited on the anodizing film of AA5252 aluminium alloy sheets. Their formation mechanism was studied in detail. The normal zone and strip zone were compared, with respect to surface brightness, porosity of anodizing film, and microstructures of the corresponding aluminium substrate tested by spectroscopic colorimeter and SEM, and SEM-EBSD. Results showed that the brightness of strip zone was lower than that of normal zone. Additionally, compared with normal zone, the porosity of anodizing film was higher, and cubic grains fewer, which located in the corresponding surface layer of aluminium substrate in strip zone. In order to further clarify the effect of grain orientation on the brightness of anodizing film, single crystal aluminium sheet with (100), (110) or (111) orientation was anodized. Results showed that the anodized (100) oriented specimen, i.e., cubic grain was brighter, whose anodizing film had lower porosity, compared with (110) and (111) oriented ones. Therefore, the formation mechanism of strip defects was proposed as uneven distribution of cubic grains. The zones with fewer cubic orientated grains were darker, and were visible as strip defects after anodizing.

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Section: Characterization Of Anodizing Film In Single Crystals With Dsupporting

confidence: 94%

Formation Mechanism of Strip Defects in Anodizing AA5252 Aluminium Alloy Sheets

et al. 2020

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“…Further, it was observed that the widths of the active front of the grain boundary attack and the crevice created by the grain boundary attack are similar, indicating that corrosion propagated preferentially along the grain boundary rather than further developing into the grain interior. This is, perhaps, associated with copper enrichment at the corrosion product/alloy matrix interface during the oxidation of aluminium from the alloy matrix, due to its less negative Gibbs free energy per equivalent (△G ° /eq) for formation of copper oxides compared with that for alumina . The copper enrichment resulted in the formation a copper‐enriched layer of a few nanometres thickness at the crevice wall behind the corrosion front, preventing corrosion further developing into the grain matrix.…”

Section: Discussionmentioning

confidence: 99%

Grain‐stored energy and the propagation of intergranular corrosion in AA2xxx aluminium alloys

Zhou

Luo

et al. 2013

Surface & Interface Analysis

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In the present study, intergranular corrosion (IGC) in AA2024 and AA2099 aluminium alloys was investigated. The IGC propagation path was examined using scanning and transmission electron microscopies. Further, electron backscatter diffraction was employed to investigate the relationship between the grain structure and the IGC susceptibility. It was found that IGC could occur at grain boundaries where second phase precipitates were absent. It was also revealed that IGC occurred at the grain boundaries that surround grains of relatively high-stored energy, and corrosion was not confined within the region immediately adjacent to the grain boundaries but had developed into the grains of relatively high-stored energy, suggesting that IGC propagated within the grains that have relatively high levels of defects.

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“…A phase change of π occurs on reflection only at the anodic oxide air/film interface since the aluminum oxide film refractive index is 1.5-1.85. [20] The interference maximum is 2nd cos θ r = (m + 0.5) λ…”

Section: Anodizing Behaviormentioning

confidence: 99%

“…Zhou et al investigated the effect of grain orientation on the morphology, dielectric breakdown, and optical behavior of anodic films formed on aluminum 2 mass% copper binary alloy. [20] The oxide film morphology, thickness, and roughness at the film/metal interface were affected by the grain orientation of the aluminum substrate, based on the results of the transmission electron microscopy (TEM) observations. They noted that the colored appearance of the anodized aluminum alloy is not related to the composition or structure of the resultant anodic oxide films.…”

Section: Anodizing Behaviormentioning

confidence: 99%

The influence of initial surface conditions on field crystallization of anodic aluminum oxide films determined by synchrotron X‐ray diffraction

Sakairi

Kikuchi

Suda

et al. 2010

Surface & Interface Analysis

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X-ray diffraction measurements were performed using synchrotron radiation at the SPring-8 facility and electrochemical techniques to investigate the effect of polishing methods and storage conditions on the crystal structure of air-formed oxide films and anodic oxide films formed on highly pure aluminum. Storage in an N 2 environment hinders local film breakdown during anodizing, and it was established that the X-ray diffraction measurements showed the presence of a γ -Al 2 O 3 in the anodic oxide film formed on mechanically polished (MP) specimens. Formation of γ -Al 2 O 3 during anodizing was inhibited by electropolishing because of the removal of the work-hardened layer that was formed on the MP by electro-polishing. The X-ray diffraction results do not show clear differences in the influence of the polishing method on the crystal structure of air formed oxide film. This is due to the very fast oxidation rate of the air-formed oxide film and very long storage times for the X-ray measurements. The anodic oxide film formed on aluminum, which has a very flat surface, shows color and the color depended on grain orientation. The electrochemical impedance of the MP specimen is slightly lower than that of the mechanically and then electrochemically polished specimen at the middle frequency range. This impedance difference may be due to formation of γ -Al 2 O 3 in the amorphous anodic oxide film and the thickness of the film.

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Effect of grain orientation on the morphology, dielectric breakdown and optical behaviour of anodic film formed on Al–2wt%Cu binary alloy

Cited by 24 publications

References 20 publications

Formation Mechanism of Strip Defects in Anodizing AA5252 Aluminium Alloy Sheets

Formation Mechanism of Strip Defects in Anodizing AA5252 Aluminium Alloy Sheets

Grain‐stored energy and the propagation of intergranular corrosion in AA2xxx aluminium alloys

The influence of initial surface conditions on field crystallization of anodic aluminum oxide films determined by synchrotron X‐ray diffraction

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