Corrosion characteristics of copper in static liquid lithium under high vacuum

Copper (Cu) materials are extensively used as heat sinks and sealing gaskets in fusion devices because they have the properties of good thermal and electrical conductivity and high plasticity. Meanwhile, liquid lithium (Li) is considered as a potential blanket coolant and tritium breeder and/or plasma facing material in fusion devices. Studying the corrosion characteristics of Cu materials by liquid Li under extreme fusion conditions is important because the corrosion of Cu by liquid Li may affect simultaneous application of these materials in fusion devices. The corrosion behavior of Cu in static liquid Li at 620 K for 15 h under high vacuum was investigated. After exposure to liquid Li, the weight loss rate of Cu in liquid Li is 466.1 g m⁻² h⁻¹, which is equivalent to 458.7 mm⋅a⁻¹ for the average corrosion depth rate. The entire surface of each specimen was seriously damaged. Visible grain boundary corrosion was observed on the surface of the specimens. Also, Cu debris entered the liquid Li from the corroded surface, resulting in considerable Cu loss from the specimen. These results demonstrate a corrosion protection grade of Cu in liquid Li of 10, Cu cannot withstand the corrosion of liquid Li under the given conditions. Additionally, the corrosion process of Cu in liquid Li at 620 K under high vacuum was studied using the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). The results from these simulations indicate that the corrosion of Cu in liquid Li is induced via physical dissolution and intergranular corrosion, where intergranular corrosion is the dominant mechanism.