Corrosion of Metals and Nickel-Based Alloys in Liquid Bismuth-Lithium Alloy

Bismuth-lithium alloys are considered as primary candidates for the reductive extraction step of on-line reprocessing of a molten salt reactor fuel. The corrosion behavior of pure metals and nickel-based alloys was studied in a liquid Bi-Li (5 mol.%) alloy at 650 degrees C. The tantalum, molybdenum, and corrosion-resistant alloys VDM(R) Alloy C-4, Hastelloy(R) G-35(R), KhN62M, VDM(R) Alloy 59 were studied as prospective materials for this liquid metal media. The corrosion rates were determined by gravimetric method as well as chemical analysis of corrosion products in Bi-Li alloy. Microstructure and chemical composition of samples of the materials and Bi-Li alloys containing the corrosion products after the tests were evaluated using inductively coupled plasma-atomic emission spectroscopy, X-ray fluorescence analysis, scanning electron microscopy, and energy dispersive spectroscopy. Metallic tantalum and molybdenum do not chemically interact with liquid Bi-Li alloy; the corrosion rate of these metals is determined only by the solubility in this medium. The corrosion rates of Ta and Mo at 650 degrees C were 0.09 and 0.07 mm/year, respectively. Nickel alloys are subjected to severe corrosion in liquid Bi-Li alloys due to dissolution of nickel in liquid bismuth. Alloys of this type cannot be used in such an environment.