Liquid lithium (Li) is a candidate material for the first wall and blanket coolants/breeders in fusion devices. Reduced activation ferritic/martensitic (RAFM) steels are also considered primary candidate structural materials for fusion reactors. Thus, the compatibility of RAFM steel with liquid Li is one of the key issues for liquid Li first walls and blankets. In this research, the corrosion behaviors of China low-activation ferritic/martensitic steel (CLF-1) in static liquid Li at 620 and 820 K under an argon atmosphere were investigated. After exposure to liquid Li, CLF-1 steel underwent slight changes in mass, while its corrosion resistance level remained at Grade 1. Due to the selective dissolution of C, Cr, Mn, and Fe and chemical reactions, grain boundary corrosion and corrosion particles of Cr carbides were observed on the corroded CLF-1 steel surface. However, the corrosion of CLF-1 steel under 820 K liquid Li was more severe than that at 620 K, and pitting corrosion occurred on the corroded CLF-1 steel surface. After exposure to 620 K of liquid Li, the hardness of the CLF-1 steel surface was the same as the initial hardness, while it decreased after exposure to 820 K of liquid Li. However, the tensile properties of CLF-1 steel showed no changes after exposure to liquid Li. Additionally, Ni and NixMny alloys were detected due to mass transfer from the 304 SS vessel to the CLF-1 surface. The results indicated that the corrosion resistance of CLF-1 steel is better than that of 304 SS and 316L SS in liquid Li.
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