MD Simulation For The Diffusion Properties Of Liquid Li-Pb Alloys

Liquid Li-Pb blanket is one of the most potentially thermonuclear fusion reactor blanket concepts in the future, and liquid Li-Pb alloy is the key material of it. Liquid Li-Pb alloy flows in the blanket with an extreme environment, it has some extend of corrosion to the structural material, and the corrosion is harmful to the safety and life of blanket, so the compatibility between liquid Li-Pb alloy and structural material is an inevitable question. The micro-mechanism of the corrosion is the interaction of solid-liquid interface, in order to study such interaction, it is essential to understand the diffusion behaviors of liquid Li-Pb. In this work, the diffusion behaviors of liquid Li, Pb and Li-Pb alloys are studied with molecular dynamics simulations using a modified analytical embedded atom method potential. Focus the analysis on the effects of temperature, composition and pressure to the diffusion behaviors. And then obtain the effects of temperature and composition to the diffusion coefficients, the density of bonding clusters and the degree of chemical ordering.The obtained results of Li and Pb diffusion behaviors are in good agreement with the experimental ones, and they are closer to the experimental values, as comparing with others simulation data. The temperature and composition have a huge effect to the diffusion behaviors of liquid Li-Pb alloy. In liquid Li50Pb50, the diffusion coefficients in liquid Li-Pb alloy are exponential increase with increasing temperature. The diffusion coefficients of component are smaller than the self-diffusion coefficients and mutual diffusion coefficient. For liquid Li-Pb alloys at1000K, the mutual diffusion coefficient increases monotonously with increasing Li content, while the diffusion coefficients of components do not increase until the concentration of Li is more than50%. It indicated that there are strong interatomic interaction between Li and Pb, which interaction lead to the formation of bonding clusters. These clusters reduce the component diffusion coefficients and enlarge the mutual diffusion coefficient. The density of bonding clusters and the degree of chemical ordering are affected by temperature and composition. They decrease with increasing temperature and get the maximum when the Li concentration is50%. Based on the calculation results, it is concluded that the temperature and composition have a huge affect to the diffusion behavior of liquid Li-Pb alloy.