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Atom probe tomography (APT) has beenused to investigate the surfaceand sub-surface microstructures of aluminum alloy 2024 (AA2024) inthe T3 condition (solution heat treated, cold worked, and naturallyaged to a substantially stable condition). This study revealed surfaceCu enrichment on the alloy matrix, local chemical structure arounda dispersoid Al20Mn3Cu2particleincluding a Cu-rich particle and S-phase particle on its externalsurface. Moreover, there was a significant level of hydrogen withinthe dispersoid, indicating that it is a hydrogen sink. These observationsof the nanoscale structure around the dispersoid particle have considerableimplications for understanding both corrosion and hydrogen embrittlementin high-strength aluminum alloys. [ABSTRACT FROM AUTHOR]

Non-heat-treatable 5xxx Al alloys exhibit good corrosion resistance but can be susceptible to intergranular corrosion in service. This study applies a cyclic strengthening method to the AA5083 alloy, resulting in a significant increase in yield strength (∼300 MPa) and tensile strength (∼385 MPa) due to the formation of Mg-Al solute clusters confirmed by scanning transmission electron microscopy and atom probe tomography. After a two-month sensitization treatment at 70 °C, the clusters delay the formation of Mg-rich precipitates at grain boundaries, enhancing the resistance to sensitization. This new approach strengthens Al-Mg alloys and offers potential for manipulating the corrosion resistance and sensitization susceptibility. • Cyclic plasticity method is applied in 5xxx alloys, breaking the strength-corrosion inversion relationship. • The formation of Mg-Al solute clusters enhances the mechanical properties of the alloy. • The clusters delay sensitization and limit the formation of intergranular Mg-rich phases. [ABSTRACT FROM AUTHOR]

High-strength aluminum alloys are important for lightweighting vehicles and are extensively used in aircraft and, increasingly, in automobiles. The highest-strength aluminum alloys require a series of high-temperature "bakes" (120° to 200°C) to form a high number density of nanoparticles by solid-state precipitation. We found that a controlled, room-temperature cyclic deformation is sufficient to continuously inject vacancies into the material and to mediate the dynamic precipitation of a very fine (1- to 2-nanometer) distribution of solute clusters. This results in better material strength and elongation properties relative to traditional thermal treatments, despite a much shorter processing time. The microstructures formed are much more uniform than those characteristic of traditional thermal treatments and do not exhibit precipitate-free zones. These alloys are therefore likely to be more resistant to damage. [ABSTRACT FROM AUTHOR]

Solute clusters affect the physical properties of alloys. Knowledge of the atomic structure of solute clusters is a prerequisite for material optimisation. In this study, solute clusters in a rapid-hardening Al-Cu-Mg alloy were characterised by a combination of atom probe tomography and density functional theory, making use of a hybrid data type that combines lattice rectification and data completion to directly input experimental data into atomistic simulations. The clusters input to the atomistic simulations are thus observed experimentally, reducing the number of possible configurations. Our results show that spheroidal, compact clusters are more energetically favourable and more abundant. [ABSTRACT FROM AUTHOR]

High-strength aluminium alloys such as AA2024-T3 are often developed by the introduction of plastic deformation to a precipitate containing microstructure. These alloys contain complex, near-surface nanostructures whose effects on localised corrosion processes have not been well understood due primarily to the difficulty of characterising these heterogeneous compositions and structures. In this work, we observed entangled oxide networks co-located with dislocation structures piled up at corroded intermetallic particles of an AA2024-T3 alloy. It was revealed that dislocation arrays act as pathways for corrosive species and promote structural degradation at interfacial regions, providing a new insight into corrosion initiation at the nano-scale. [ABSTRACT FROM AUTHOR]