The alloying processes in solid-solid and liquid-solid Li-Pb interfaces with atomistic simulations

The alloying processes of solid-solid (at 400 K) and liquid-solid (at 500 K) Li-Pb interfaces are investigated by molecular dynamics simulations with embedded-atom method (EAM) potentials. As a comparison, a critical Li-Pb interface at 450 K near the melting point of Li is also studied. Three-stage feature, including the interface disordering, nucleation and growth of an intermetallic phase (B2-LiPb), has been clearly observed in these three cases. It is found that the alloying products are the same, however, the nucleation of the intermetallic phase at the solid-solid Li-Pb interface is earlier than that in the other two cases. The block Li in the solid-solid interface sample keeps the body-centered cubic structure during the course of simulation, while in the critical Li-Pb interface sample, it collapses from the excessive lattice distortion. As simulation time increasing, the interface widths increase gradually with decreasing growth rates, and the growth rate is the largest for the liquid-solid interface and the smallest for the solid-solid interface. The interface width of the solid-solid Li-Pb interface saturates at about 0.3 ns for the diffusion barrier-B2-LiPb almost traversed across the entire interface plane at that time.