Molecular dynamics simulation of alloying during sintering of Li and Pb metallic nanoparticles

The sintering-alloying process of Li and Pb nanoparticles at three typical temperatures, 200 K, 250 K and 400 K, are studied by molecular dynamics simulation with the modified analytic embedded-atom model (MAEAM) potential. The three stages, containing the disordering of the contact region, the nucleation and growth of a new phase at the mixed region, are distinctly observed in the three sintering processes. It is verified that the alloying products are B2-LiPb. However, the amount of B2-LiPb is the fewest at 250 K for the reason that an alloying process like liquid-solid sintering occurs as a result of the collapse of Li nanoparticle although the temperature of 250 K is lower than the melting points of Li and Pb nanoparticles. With time, the thickness of the mixed region thickens gradually as growth rate decreases. Besides, the growth rate increases with temperature rising. Moreover, the values of the shrinkage ratio and the average nearest coordination number are increased with time among the three sintering temperatures. As a result, the sinterability and the alloying degree are the highest at 400 K and the lowest at 200 K. In addition, the sphere polycrystalline structure forms at 400 K, while the egg-like configurations are found at the other two temperatures within the simulation time. Furthermore, surface segregation and its effect on sintering alloying process are discussed.