One possible explanation of the presence of Ni metal signal in these experiments is due to a radiation-induced reduction of Ni 2+ to Ni 0 . While this might have been a contributing factor in our experiments, it was not the dominant source of metallic Ni for a few reasons. Firstly, our fluoride salt was contained in a BN cell rather than quartz which attenuated the Xray beam intensity significantly and reduced the radiation dose. Secondly, we see in Fig. the metallic Ni concentration gradient that emanates directly from the NiCr foil and does not show a peak located at the X-ray beam location (3 mm). Lastly, the concentration of Ni metal in our experiments is highly dynamic with peaks caused by metal pieces moving through the beam rather than a steady increase that would be caused by the static beam placement. Therefore, we propose an alternative explanation that small Nirich grains were liberated from the foil due to the dissolution of Cr. Previous X-ray tomography and quasi in situ TEM observations of NiCr wires in molten KCl -MgCl 2 showed dealloying, grain boundary attacks, and salt penetration in cracks and pores . Such dealloying leaves behind a sponge-like structure of Ni-rich grains that would easily detach into the solution. When caught in the X-ray beam, these pieces resulted in the dramatic spikes in Ni metal fluorescence shown in Figs. 6b and 7a. As expected, there's a coincident increase in Ni 2+ concentration due to some dissolution of ions from metal pieces.