The combination of passive solute sampling by diffusive gradients in thin films (DGT) and spatially resolved chemical analysis by LA-ICP-MS allows for non-destructive visualisation and quantification (mapping) of elemental mobilisation processes in situ. Traditionally, DGT LA-ICP-MS was being used for environmental studies, but recent developments opened the door for studying corrosion processes in materials science [1]. This study presents a novel application of DGT LA-ICP-MS for in situ mapping of corrosion processes, with a focus on localised pitting corrosion of aluminium (Al) workpieces, primarily formed of Al (w = 99.5 %) and further including traces of constituent elements such as Fe (w = 0.375 %), Zn (w = 0.0046 %), and Cu (w = 0.0014 %). Since pitting corrosion initiates the formation of microcracks and cavities in Al metal, which can act as a starter for fatigue cracks and lead to metal failure, it’s important to better understand the corrosion processes of Al workpieces. Polyacrylamide- and polyurethane-based DGT binding gels with homogeneously distributed iminodiacetate (Chelex 100) and TiO2 (Metsorb) binding phases were evaluated and applied to the Al samples and immersed for 24- and 72 hours in a NaCl solution (w = 1.5%, pH = 4.5). The DGT gels were analysed by LA-ICP-MS and quantification of corrosive metal fluxes was accomplished by linear calibration using DGT gel standards with known analyte mass loadings. The first results of this study showed that DGT LA-ICP-MS enables in situ mapping of spatiotemporal patterns of localised multi-elemental (Al, Fe, Cu, Zn) metal solubilisation and release accompanied by different corrosion processes. The method has a high potential for application in materials science, providing quantitative information on the spatiotemporal reaction dynamics of corrosion processes.

[1] S. Wagner et al., “In situ spatiotemporal solute imaging of metal corrosion on the example of magnesium,” Analytica Chimica Acta, vol. 1212, p. 339910, 2022, doi: 10.1016/j.aca.2022.339910.