An embedded-atom method interatomic potential for lithium-iron binary system and its applications in the liquid first wall system

Molecular dynamics simulations have been widely used to investigate the thermodynamic and structural properties of liquid lithium (Li) and solid substrates as the concept of liquid divertor of fusion devices becomes more and more popular. However, this kind of studies are limited by the complexity of constructing the interatomic potentials for alloy systems. In this work, a new interatomic potential based on the embedded-atom method (EAM) was developed for the Li-Fe (iron) binary system. The parameters of the potential were optimized based on the first-principles calculations and experimental results of the elemental and binary properties of Li-Fe system. Results show that the new potential provides good descriptions of the mechanical and thermal properties of solid alpha-Fe and liquid Li including the elastic moduli of alpha-Fe and the viscosity of liquid Li. Especially, the addition of the surface energies and interfacial adhesion work into the fitting database guarantees that the wetting properties of liquid Li on alpha-Fe surfaces are well predicted. The contact angle on {100} Fe surface was calculated to be 58.4 degrees which agrees very well with the experimental results. The new potential was applied to simulate the tensile tests of Li-Fe alloy and the Li flow in an alpha-Fe capillary channel. Results suggest that this potential is suitable for simulations of a variety of processes such as the surface corrosion of alpha-Fe by liquid Li, and the wetting and spreading of liquid Li on alpha-Fe surfaces, which are of interests in the context of the development of liquid divertor in future fusion reactors.