| Abstract Scope |
The progression of localized corrosion is often accompanied by the development of porosity within materials, creating internal pathways that facilitate the ingress of external environments into the material's interior. Visualizing these porosity networks is crucial for understanding the penetration mechanisms of corrosion. In this study, we employed focused ion beam–scanning electron microscopy (FIB-SEM) 3D tomography to characterize the distinct porosity morphologies in several Ni-Cr-based alloys after exposure to FLiNaK molten salt. We identified a highly localized form of corrosion, termed one-dimensional (1D) wormhole corrosion, which drives rapid salt penetration in Ni-20Cr. While similar 1D features were also observed in SS 316 and Incoloy 800H, their porosity-network structures exhibited notable differences. To better understand the interplay between different corrosion modes, we developed a quantitative method to decouple 1D wormhole corrosion from two-dimensional (2D) intergranular attack. This approach enables precise evaluation of corrosion morphology evolution as a function of alloy composition, offering insights for the design of materials with enhanced resistance in molten salt environments. |