How solute atoms control aqueous corrosion of Al-alloys

Abstract

Aluminum alloys play an important role in circular metallurgy due to their good recyclability and 95% energy gain when made from scrap. Their low density and high strength translate linearly to lower greenhouse gas emissions in transportation, and their excellent corrosion resistance enhances product longevity. The durability of Al alloys stems from the dense barrier oxide film strongly bonded to the surface, preventing further degradation. However, despite decades of research, the individual elemental reactions and their influence on the nanoscale characteristics of the oxide film during corrosion in multicomponent Al alloys remain unresolved questions. Here, we build up a direct correlation between the near-atomistic picture of the corrosion oxide film and the solute reactivity in the aqueous corrosion of a high-strength Al-Zn-Mg-Cu alloy. We reveal the formation of nanocrystalline Al oxide and highlight the solute partitioning between the oxide and the matrix and segregation to the internal interface. The sharp decrease in partitioning content of Mg in the peak-aged alloy emphasizes the impact of heat treatment on the oxide stability and corrosion kinetics. Through H isotopic labelling with deuterium, we provide direct evidence that the oxide acts as a trap for this element, pointing at the essential role of the Al oxide might act as a kinetic barrier in preventing H embrittlement. Our findings advance the mechanistic understanding of further improving the stability of Al oxide, guiding the design of corrosion-resistant alloys for potential applications.

Oxygen Impurity-Tuned Structure and Adhesion Properties of the Cu/SiO2 Interface

“…The heterogeneous interface systems have wide applications in the variety of engineering fields, such as oxide-dispersion-strengthened alloy, thermal barrier coating, anticorrosive coating, catalyst, and microelectronics . The reason is that the presence of heterogeneous interfaces usually imparts the peculiar properties to engineering and functional materials such as strain hardening, , thermal resistance, , irradiation resistance, , corrosion resistance, excellent catalytic activity, , etc. Moreover, these properties are strongly affected by the interfacial interaction and bonding property that may change with the service environments and interface/defect interaction.…”

Mapping elemental solutes at sub-picogram levels during aqueous corrosion of Al alloys using diffusive gradients in thin films (DGT) with LA-ICP-MS

“…Given their high strength-to-weight ratio, infinite recyclability, and energy-efficient fabrication when produced from scrap, they are essential building blocks towards sustainable transportation and circular metallurgy [ 5 – 7 ]. Besides, Al alloys are attractive for their high corrosion resistance, owing to a dense passivated oxide film formed on their surface, preventing uniform degradation for enhanced material longevity [ 8 ]. However, Al alloys, as other metallic alloys, suffer from localized corrosion when exposed to aqueous environments [ 9 , 10 ].…”