Dealloying of Al2Cu, Al7Cu2Fe, and Al2CuMg intermetallic phases to form nanoparticulate copper films

Lebouil, S.; Tardelli, Joffrey; Rocca, Emmanuel; Volovitch, P.; Ogle, K.

doi:10.1002/maco.201307550

Cited by 54 publications

(32 citation statements)

References 29 publications

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“…This is due to the selective dissolution or dealloying of Al 7 Cu 2 Fe phase. A similar phenomenon has been reported in the work of Lebouil et al 37 For some large pits in the over-aged samples, the remnants of particles were not found because of the falling-out or dissolution of the remnants.…”

Section: Resultssupporting

confidence: 89%

Effect of Cu Content and Aging Conditions on Pitting Corrosion Damage of 7xxx Series Aluminum Alloys

Wang

Huang

et al. 2015

J. Electrochem. Soc.

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The corrosion behavior and microstructure of AA7055 alloy with a high Cu content, and a Cu-free Al-Zn-Mg alloy in various aging conditions were studied. Polarization measurements and ASTM B117 salt-spray exposure were used to assess the corrosion characteristics. Transmission electron microscope and atom probe tomography were used to evaluate the microstructure and the composition of precipitates. The matrix composition of AA7055 changed with aging because of precipitation. Thus, the galvanic relationship between Al 7 Cu 2 Fe particles and the surrounding matrix correspondingly changed, which affected the susceptibility to pitting corrosion attack. The susceptibility to pitting corrosion damage of AA7055 was found to decrease according to: over-aged samples > under-aged samples > peak-aged sample. However, aging had only a small influence on pitting corrosion damage for the Cu-free Al-Zn-Mg alloy. Furthermore, despite the more active breakdown potential of the Cu-free Al-Zn-Mg alloy, this alloy exhibited less severe pitting corrosion damage than AA7055, in particular for the over-aged samples. This was attributed to the weaker galvanic coupling between Al 3 Fe particles and the surrounding matrix. Although Cu in the intermetallic particles is detrimental to pitting resistance, the galvanic effect can be reduced by increasing the matrix Cu content. High-strength precipitation-hardenable aluminum alloys are commonly used for structural components of aircraft due to their high strength-to-density ratio.1 However, they are also very susceptible to pitting corrosion, in particular for Navy aircraft subjected to extended periods of salt water spray and/or salt fog.2 These corrosion pits can act as initiation sites for corrosion fatigue cracks and reduce the fatigue life, which is a significant damage mechanism in aging aircraft structures. 2,3From a microstructural viewpoint, initiation of localized pitting corrosion is often associated with coarse cathodic intermetallic particles (IMPs), such as Al 7 Cu 2 Fe, Al 3 Fe, Al 2 Cu, and Al 2 CuMg, which are common in 2xxx and 7xxx series Al alloys.4-9 A number of studies have been performed on electrochemical characteristics of these particles. 4,8,9 In general, they act as local cathodes and sustain oxygen reduction at a high rate to drive the pitting corrosion attack at the particle-matrix interface. In addition, a few studies have related the precipitate size to metastable and stable pitting corrosion in Al-Cu-Mg and Al-Zn-Mg-Cu alloys.10-13 Ralston et al. 11,12 suggested that there was a critical S-phase precipitate size range from ∼3 -8 nm to trigger pitting events. Aged samples with smaller precipitate size had pitting resistance similar to as-quenched samples. The susceptibility to pitting corrosion was greatly enhanced after prolonged aging to create precipitates larger than this critical size range. Gupta et al. 13 reported that a critical precipitate size existed for a transition in electrochemical behavior of 7xxx series Al alloys. For Cu-rich AA7150, increased ...

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Section: Resultssupporting

confidence: 89%

Effect of Cu Content and Aging Conditions on Pitting Corrosion Damage of 7xxx Series Aluminum Alloys

Wang

Huang

et al. 2015

J. Electrochem. Soc.

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“…Experimental studies also revealed the selective dissolution of Al from θ-Al 2 Cu, and suggested that crystallographic defects, such as stacking faults and dislocations, facilitate de-alloying of θ-Al 2 Cu. 13,41,42 The planar-extended and vertical-extended dislocation core could operate as precursor for de-alloying of θ-Al 2 Cu because of the increased local stored energy. Moreover, dislocation climb driven by their interaction will create a high population of vacancies.…”

Section: Discussionmentioning

confidence: 99%

Dislocations interaction induced structural instability in intermetallic Al2Cu

et al. 2017

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Intermetallic precipitates are widely used to tailor mechanical properties of structural alloys but are often destabilized during plastic deformation. Using atomistic simulations, we elucidate structural instability mechanisms of intermetallic precipitates associated with dislocation motion in a model system of Al 2 Cu. Interaction of non-coplanar <001> dislocation dipoles during plastic deformation results in anomalous reactions-the creation of vacancies accompanied with climb and collective glide of <001> dislocation associated with the dislocation core change and atomic shuffle-accounting for structural instability in intermetallic Al 2 Cu. This process is profound with decreasing separation of non-coplanar dislocations and increasing temperature and is likely to be operative in other non-cubic intermetallic compounds as well.

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“…1 The potential differences between the IMPs and the matrix may result in localized dissolution of the matrix or dealloying of the IMP. 2 The most common IMPs present in 2xxx and 7xxx series Al alloys include Al 2 CuMg (S-phase), Al 2 Cu (θ-phase), Al 7 Cu 2 Fe (β-phase), MgZn 2 (η-phase) and Mg 2 Si. [3][4][5] IMPs containing Cu and Fe, such as Al 2 Cu.…”

mentioning

confidence: 99%

“…6 and Al 7 Cu 2 Fe, 7 are considered to be cathodic with respect to the matrix, acting as local cathodes and thus promoting cathodic reactions such as oxygen reduction. In contrast, Mg-rich IMPs, such as Al 2 CuMg, are considered anodic relative to the matrix, resulting in selective dissolution and concomitant Cu-enrichment of the IMP. 8 These localized corrosion events may eventually trigger other corrosion forms, such as stress corrosion cracking or intergranular corrosion.…”

mentioning

confidence: 99%

First-Principle Calculation of Volta Potential of Intermetallic Particles in Aluminum Alloys and Practical Implications

Jin

Liu

Zhang

et al. 2017

J. Electrochem. Soc.

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This work presents a theoretical assessment of galvanic (relative) nobility of four intermetallic particles (IMPs), Al 2 Cu, Al 2 CuMg, Mg 2 Si and MgZn 2 , in aluminum alloys through work function calculation based on density functional theory (DFT). The concepts of work function, Volta potential and relative nobility are discussed with respect to the IMPs and aluminum matrix. The calculated Volta potentials are compared with reported experimental Volta potentials measured by scanning Kelvin probe force microscopy (SKPFM). Various crystal faces and terminal types are examined in the DFT calculation, showing that these two factors have a significant effect on the work function value. Considering the large divergence in the reported experimental data, the comparison shows a general agreement between the calculated and experimental Volta potential data for the investigated IMPs. The DFT calculations provide theoretical explanations for several experimental phenomena. The results demonstrate that DFT calculation is a valuable theoretical approach for assessment of the relative nobility of different phases in the alloys, providing complementary information to experimental data from SKFPM. Moreover, the implications of the calculated Volta potentials are discussed with respect to the corrosion potentials. The addition of various alloying elements into the aluminum (Al) matrix to improve mechanical performance of Al alloys may simultaneously increase their susceptibility to localized corrosion. This is mainly due formation of intermetallic particles (IMPs) that may trigger micro-galvanic corrosion along the interface between the IMPs and the alloy matrix.1 The potential differences between the IMPs and the matrix may result in localized dissolution of the matrix or dealloying of the IMP. 2The most common IMPs present in 2xxx and 7xxx series Al alloys include Al 2 CuMg (S-phase), Al 2 Cu (θ-phase), Al 7 Cu 2 Fe (β-phase), MgZn 2 (η-phase) and Mg 2 Si.3-5 IMPs containing Cu and Fe, such as Al 2 Cu. 6 and Al 7 Cu 2 Fe, 7 are considered to be cathodic with respect to the matrix, acting as local cathodes and thus promoting cathodic reactions such as oxygen reduction. In contrast, Mg-rich IMPs, such as Al 2 CuMg, are considered anodic relative to the matrix, resulting in selective dissolution and concomitant Cu-enrichment of the IMP.8 These localized corrosion events may eventually trigger other corrosion forms, such as stress corrosion cracking or intergranular corrosion.9 Therefore, micro-galvanic corrosion effects between IMPs and the Al matrix is considered to be of utmost importance for the overall service performance of Al alloys.In 1987, Stratmann started to use the Kelvin probe to investigate corrosion properties of metals under thin electrolyte films.10 His measurements revealed a linear relationship between Volta potential and corrosion potential of Cu, Zn, Fe and other metals. Later, the scanning Kelvin microprobe was developed and used for Volta potential measurements of several metals in humid atmospheres.11 Du...

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Dealloying of Al₂Cu, Al₇Cu₂Fe, and Al₂CuMg intermetallic phases to form nanoparticulate copper films

Cited by 54 publications

References 29 publications

Effect of Cu Content and Aging Conditions on Pitting Corrosion Damage of 7xxx Series Aluminum Alloys

Effect of Cu Content and Aging Conditions on Pitting Corrosion Damage of 7xxx Series Aluminum Alloys

Dislocations interaction induced structural instability in intermetallic Al2Cu

First-Principle Calculation of Volta Potential of Intermetallic Particles in Aluminum Alloys and Practical Implications

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