Effect of substrate chemistry on prenucleation by ab initio MD simulation

Abstract

Prenucleation refers to the phenomenon of atomic ordering in the liquid close to the substrate/liquid interface at temperatures above the liquidus. Based on our previous work on the structural effect (i.e., lattice misfit) on prenucleation, here we investigate the effect of substrate chemistry on prenucleation by ab initio molecular dynamics (MD) simulations using the supercell approach. Our study has shown significant influences of the substrate chemistry on substrate–metal spacing, atomic layering and in–plane ordering of the liquid Al at temperatures above liquidus. Attractive substrate promotes prenucleation while repulsive substrate impedes prenucleation. We also find that the effect of substrate chemistry is local and mainly confined to the first layer of liquid atoms closest to the substrate/liquid interface.