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

Abstract

This study explores the surface chemistry of Inconel 625 samples exposed to molten LiCl-Li 2 O-Li solutions at 650°C for 500 and 1000hr and aims to understand the effect of solvated Li on corrosion behavior in molten LiCl-Li 2 O-Li. The surfaces of Inconel 625 samples were analyzed using X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. The oxide films formed on the surface of the samples in the absence of Li is composed of LiCrO 2 , with small contributions of Li 2 CrO 4 and NiFe x Cr 2-x O 4 . The presence of Li was observed to destabilize these compounds, resulting in a primarily metallic surface with trace amounts of oxidized Cr, Mo, and Nb present depending on the concentration of Li in solution.

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

“…Li is not detectable via EDS, however, spectroscopic analysis has definitively shown this compound to be LiCrO 2 . 38 The presence of Li in the molten LiCl-Li 2 O solution destabilizes the oxide layer and forms a very porous microstructure that is similar in appearance to a Ni foam. EDS analysis of these areas consistently showed greater than 80at%Ni, with high depletion of Cr, Mo, and Nb, although the Ni:Fe ratio remained close to that of the base material.…”