Atomic size and chemical effects of alloying elements Cu, Mg and Si on the structure and dynamics of molten 8090-based AlLi alloy

The structural and dynamical properties of liquid Al91Li9 and Al91Li9M3 (M=Cu, Mg, Si) alloys are investigated by means of ab initio molecular dynamic simulation. Pair distribution function analysis suggests that the atomic distances of Li-Li and Al-Li decrease after addition of alloying elements. The additive Cu and Si are manifested surrounded by Al and Li and hardly meet each other owing to the effects of atom size and their negative mixing enthalpy with Li. The topological environments of Al and Li in Al91Li9 are changed significantly by adding minor alloying elements. The diffusion of Al and Li is hindered by alloying elements, among which Cu and Si play more significant role. Furthermore, the metalloid additive Si illustrates different effects from the metallic additive Cu and Mg on the diffusivity of Al91Li9 liquid alloys.