DFT Modelling of Cu Segregation in Al-Cu Alloys Covered by an Ultrathin Oxide Film and Possible Links with Passivity

Cornette, Pascale; Costa, Dominique; Marcus, Philippe

doi:10.3390/met7090366

Cited by 10 publications

(11 citation statements)

References 41 publications

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“…This is assigned to the preferential oxidation of the Al as already discussed. [29] This Cu enrichment of the matrix at the metal/oxide interface has been previously predicted by computational work [40], where the authors concluded that the presence of oxide could favour Cu segregation at the matrix/oxide interface. Thus, the matrix is mainly composed of metallic aluminium, enriched with copper at the metal/oxide interface, and is covered by an aluminium oxide layer.…”

Section: In Depth Chemical Composition Of the Alloy Surface By Tof-sims Analysessupporting

confidence: 70%

The native oxide film on a model aluminium-copper alloy studied by XPS and ToF-SIMS

et al. 2020

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Surface analytical techniques were used to characterize the chemical composition and the thickness of the surface oxide on an AlCu2.2%at alloy sample.ToF-SIMS analyses show that the oxide layer is thinner on the intermetallic particles (IMPs) as compared to the Al matrix. Combined with XPS, analyses reveal that IMPs are covered by aluminium and copper(I) oxide whereas the Al matrix is covered by aluminium oxide. Moreover, metallic copper segregates at the oxide/metal interface on both matrix and IMPs.The heterogeneities at the metal/oxide interfaces suggest that complex galvanic effects could occur between IMP and matrix substrate, and within the IMPs.

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Section: In Depth Chemical Composition Of the Alloy Surface By Tof-sims Analysessupporting

confidence: 70%

The native oxide film on a model aluminium-copper alloy studied by XPS and ToF-SIMS

et al. 2020

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“…The thickness of the film is about 5 Å, which is comparable to the thickness associated with the oxidation-induced potential gradient and in line with the limiting thickness obtained in ultrahigh vacuum (UHV) experiments . A film of comparable thickness, although based on the structure of γ-Al 2 O 3 , was also utilized by one of us in previous studies as a plausible model in the early stages of passivation. − …”

Section: Computational Methods and Technical Detailssupporting

confidence: 73%

Insight into the Bonding of Silanols to Oxidized Aluminum Surfaces

2018

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In the context of elucidating the mechanism by which siloxane-based sol−gel coatings adhere to the surface, the adsorption of a model silanol molecule, CH 3 Si(OH) 3 , and its oligomers (up to the trimer) on oxidized and fully hydroxylated aluminum substrates is described using density functional theory (DFT). To link our calculations with the synthesis of siloxane-based sol−gel coatings, the focus is given on the condensation mechanism. We find that the formation of a monodentate bonding mode with the hydroxylated surface via the condensation mechanism is exothermic by ≥0.5 eV in all considered cases. In contrast, the formation of a bidentate bonding mode is exothermic only for the trimer. However, taking entropic contributions into account, we find that the formation of the bidentate bonding mode is exergonic already for the dimer due to favorable entropic effects of a liberated water molecule during the reaction. In contrast, the reaction entropy is unfavorable for the monodentate formation because the effects of the immobilized silanol molecule counteract and surpass those of the liberated water molecule. The monodentate to bidentate transformation is therefore determined by the interplay between entropy and energy, and we find that the longer the oligomer chain, the more likely is the bidentate formation due to increasingly favorable reaction energies. These results further reveal that for the silanol monomer, additional molecule−surface chemical bonds do not form via the condensation mechanism due to the strained configuration it has to adopt in the bidentate bonding mode.

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“…In particular, in the case of Al alloys and/or intermetallic particles (IMPs), several joint experimental and theoretical works have been performed, where theory helps in interpreting the experimental data. [1][2][3][4][5][6][7][8][9] In other works, DFT models are used to represent typical corrosion situations e.g. alloy dissolution.…”

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confidence: 99%

Relation between Surface Composition and Electronic Properties of Native Oxide Films on an Aluminium-Copper Alloy Studied by DFT

Cornette

Costa

Marcus

2020

J. Electrochem. Soc.

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We performed a DFT modelling of Al2O3(001)/Al(001) and Al2O3(001)/Al2Cu(001) surfaces and of Al(010)/Al2Cu(010) interfaces covered with Al2O3(001). We focus on the electronic properties (work function, valence band and electronic gap) computed for the different models. We show that both on Al and Al2Cu, the oxide layer induces a significant increase in work function. The effect of the composition of the first metallic layer underneath the oxide film is also investigated. Cu enrichment under the oxide film induces an increase in work function, however less marked than the one caused by the oxide layer. We show that the work function increase is due to a charge transfer from the interfacial metal layer to the oxide layer. The same result is found at the oxidized Al(010)//Al2Cu(010) interface. The work function of the oxidized Al2Cu zone is higher than the one of oxidized Al.

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DFT Modelling of Cu Segregation in Al-Cu Alloys Covered by an Ultrathin Oxide Film and Possible Links with Passivity

Cited by 10 publications

References 41 publications

The native oxide film on a model aluminium-copper alloy studied by XPS and ToF-SIMS

The native oxide film on a model aluminium-copper alloy studied by XPS and ToF-SIMS

Insight into the Bonding of Silanols to Oxidized Aluminum Surfaces

Relation between Surface Composition and Electronic Properties of Native Oxide Films on an Aluminium-Copper Alloy Studied by DFT

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