Resolving the reactive liquid-solid corroding interface at the near atomic level to understand the influence of alloy and electrolyte composition (CorrInt)

• Applicant: Dr. Tim M. Schwarz
• Subject Area: Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials ; Biomaterials ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 551061178

In general, Mg has two key properties that make it suitable for very different applications. The high strength to weight ratio makes Mg a potential alternative to Al alloys for lightweight applications. In addition, Mg is biocompatible and biodegradable, making it an excellent candidate for replacing temporary implants made of Ti or steel. Both applications are limited by the rapid and uncontrollable corrosion of Mg alloys, which is still not fully understood. The influence of different alloying elements and their segregation towards the interface, as well as different electrolytes, on corrosion and the corrosion layers formed is unknown at the atomic scale. Understanding the corrosion processes at the liquid-solid interface requires analytical methods with high local and chemical analytical capability and, ideally, the ability to measure these reactions in-situ at the atomic length scale. However, currently known methods have various limitations in spatial or chemical resolution, leading to a knowledge gap in the understanding of complex phenomena at liquid-solid interfaces and hindering the development of strategies to improve or influence the properties. Atom Probe Tomography (APT) can fill this gap as it is an analytical imaging technique that provides a three-dimensional reconstruction of the measured volume with high spatial resolution and the same chemical sensitivity across the entire periodic table, even for light elements such as hydrogen. This project aims to decipher the complex chemistry of reactive solid-liquid interfaces at the atomic scale using a newly developed sample preparation method. The samples will be prepared under cryogenic conditions and will allow to study the reaction front during corrosion of a Mg alloy used as a biodegradable implant "quasi" in-situ using APT. This paves the way to analyze the reactive liquid-solid interfaces at the nanoscale with high chemical sensitivity and opens up new scientific opportunities to study these complex interfacial processes and to unravel the influence of different alloying elements and electrolytes on the corrosion mechanism.

• DFG Programme: WBP Position