TY - JOUR
T1 - First-Principles Surface Interaction Studies of Aluminum-Copper and Aluminum-Copper-Magnesium Secondary Phases in Aluminum Alloys
AU - da Silva, Thiago H.
AU - Nelson, Eric B.
AU - Williamson, Izaak
AU - Efaw, Corey M.
AU - Sapper, Erik
AU - Hurley, Michael F.
AU - Li, Lan
N1 - Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2018/5/1
Y1 - 2018/5/1
N2 - First-principles density functional theory-based calculations were performed to study θ-phase Al 2 Cu, S-phase Al 2 CuMg surface stability, as well as their interactions with water molecules and chloride (Cl − ) ions. These secondary phases are commonly found in aluminum-based alloys and are initiation points for localized corrosion. Density functional theory (DFT)-based simulations provide insight into the origins of localized (pitting) corrosion processes of aluminum-based alloys. For both phases studied, Cl − ions cause atomic distortions on the surface layers. The nature of the distortions could be a factor to weaken the interlayer bonds in the Al 2 Cu and Al 2 CuMg secondary phases, facilitating the corrosion process. Electronic structure calculations revealed not only electron charge transfer from Cl − ions to alloy surface but also electron sharing, suggesting ionic and covalent bonding features, respectively. The S-phase Al 2 CuMg structure has a more active surface than the θ-phase Al 2 Cu. We also found a higher tendency of formation of new species, such as Al 3+ , Al(OH) 2+ , HCl, AlCl 2+ , Al(OH)Cl + , and Cl 2 on the S-phase Al 2 CuMg surface. Surface chemical reactions and resultant species present contribute to establishment of local surface chemistry that influences the corrosion behavior of aluminum alloys.
AB - First-principles density functional theory-based calculations were performed to study θ-phase Al 2 Cu, S-phase Al 2 CuMg surface stability, as well as their interactions with water molecules and chloride (Cl − ) ions. These secondary phases are commonly found in aluminum-based alloys and are initiation points for localized corrosion. Density functional theory (DFT)-based simulations provide insight into the origins of localized (pitting) corrosion processes of aluminum-based alloys. For both phases studied, Cl − ions cause atomic distortions on the surface layers. The nature of the distortions could be a factor to weaken the interlayer bonds in the Al 2 Cu and Al 2 CuMg secondary phases, facilitating the corrosion process. Electronic structure calculations revealed not only electron charge transfer from Cl − ions to alloy surface but also electron sharing, suggesting ionic and covalent bonding features, respectively. The S-phase Al 2 CuMg structure has a more active surface than the θ-phase Al 2 Cu. We also found a higher tendency of formation of new species, such as Al 3+ , Al(OH) 2+ , HCl, AlCl 2+ , Al(OH)Cl + , and Cl 2 on the S-phase Al 2 CuMg surface. Surface chemical reactions and resultant species present contribute to establishment of local surface chemistry that influences the corrosion behavior of aluminum alloys.
KW - localized corrosion
KW - aluminum alloys
KW - chloride ions
KW - density functional theory
KW - θ-phase Al2Cu
KW - S-Phase Al2CuMg
UR - http://www.scopus.com/inward/record.url?scp=85041420259&partnerID=8YFLogxK
UR - https://scholarworks.boisestate.edu/mse_facpubs/339
U2 - 10.1016/j.apsusc.2017.12.256
DO - 10.1016/j.apsusc.2017.12.256
M3 - Article
SN - 0169-4332
VL - 439
SP - 910
EP - 918
JO - Applied Surface Science
JF - Applied Surface Science
ER -