Effect of Metallic Li on the Corrosion Behavior of Inconel 625 in Molten LiCl-Li₂O-Li

Abstract

The corrosion behavior of Inconel 625 in molten LiCl solutions maintained at 650°C and containing various quantities of Li 2 O and metallic Li was studied for possible application in the electroreduction of used oxide-based nuclear fuel. This study focusses on the morphological and elemental changes on the surface of the samples with an emphasis on cross-sectional analyses conducted using focused ion beam microscopy. In the absence of metallic Li, a stable oxide film is formed that limits the corrosion of the base material to 0.07mm/year. However, in the presence of metallic Li, the formation of this film is impeded, resulting in dealloying of the base material and the formation of a highly porous microstructure composed primarily of Ni.

Li2O Entrainment during UO2 Reduction in Molten LiCl-Li2O: Part II. Effect of Cathodic Reduction Mechanism

“…Producing more Li than can be consumed by the UO 2 , indirect reduction dominating, may also lead to an increased Li concentration in the bulk which has been shown to have deleterious effects on containment materials. 20 Salt sampling.-During these and other tests periodic dip samples were taken of the electrolyte and then the Li 2 O concentration was measured via acid-base titration. The amount of Li 2 O added to the crucible was enough to achieve 1 wt% in the salt.…”

Effect of Metallic Li on the Surface Chemistry of Inconel 625 Exposed to Molten LiCl-Li2O-Li

“…Previous work from our group reported the morphological and elemental changes to the base material surface and cross section via scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) for both stainless steel 316 (SS316) and I625. 1,14 The results presented there showed that a stable Cr-based oxide film forms on the surface of I625 upon exposure to molten LiCl-Li 2 O solutions at 650°C in the absence of Li 0 . 1 This oxide film was found to limit the corrosion of these samples to a rate of approximately 0.05 to 0.07 mm/year.…”

“…A thorough introduction including the motivation and background for this work is provided in an earlier study. 1 Briefly, the formation of metallic Li in the molten LiCl-Li 2 O electrolyte used for the electrolytic reduction of oxide based UNF has been noted by a number of researchers to occur. 2,3 Formation of metallic lithium is a side reaction that occurs as a result of the high reduction potential in the process that is necessary to reduce uranium oxide to uranium metal.…”

“…1 This oxide film was found to limit the corrosion of these samples to a rate of approximately 0.05 to 0.07 mm/year. 1 However, in the presence of Li, this oxide film was destabilized, resulting in the preferential dissolution of the active alloying elements, namely Cr, Mo, and Nb, and a porous microstructure at the sample surface (1, supplemental information Figs. S4 and S5).…”

Additional data and experimental setups, for a comparative study of alloys in contact to eutectic melts for thermal storage

“…The stepwise thermal purification process utilised in this work Ref. [main article] was based on previous studies [4] , [5] , [6] . The purification process conducted in this study followed these steps; (i) The chloride mixture was first dried at 100 °C for at least five hours.…”