Visualizing time-dependent microstructural and chemical evolution during molten salt corrosion of Ni-20Cr model alloy using correlative quasi in situ TEM and in situ synchrotron X-ray nano-tomography

In situ monitoring of corrosion processes is important to fundamentally understand the kinetics and evolution of materials in harsh environments. A quasi in situ transmission electron microscopy technique was utilized to study microstructural and chemical evolution of a Ni-20Cr disc sample exposed to molten KCl-MgCl2 salt for 60 s in consecutive 20 s iterations. In situ synchrotron X-ray nano-tomography was performed to characterize the morphological evolution of a Ni-20Cr microwire exposed to molten KCl-MgCl2. Both techniques captured key corrosion events and revealed mechanisms at different time and length scales, potentially bringing greater insights and deeper understanding beyond conventional analysis. [Display omitted] •We demonstrated a quasi in situ TEM technique to investigate early stages of molten salt corrosion in Ni-20Cr model alloy.•Quasi in situ TEM observations identified grain boundary attack, dealloying and salt penetration in cracks/pores.•In situ synchrotron X-ray nanotomography provided real-time visualization of morphological evolution.•Quasi in situ TEM and in situ X-ray nanotomography elucidate early and later stages of corrosion mechanisms, respectively.