Abstract

Heterogeneous nucleation is almost invariably responsible for the solidification of metals in practice, and this process governs the fabrication techniques for numerous advanced materials. Hence, a profound understanding of the physical essence of heterogeneous nucleation at the atomic scale is urgently required. In this study, we systematically investigate the substrate orientation dependence of liquid ordering and crystal nucleation in Al melts using molecular dynamics simulations (MD). Results show that the ability of nanoparticles to promote crystal nucleation originates from their capacity to facilitate the formation of crystal-like structures at the melt–substrate interface. Regarding the influence of substrate orientations on the ordered layers at the Al liquid–solid interface, the following trends are observed: the (111) plane has the strongest induction ability, followed by the (110) and then the (100) planes. For in-plane ordering, the (100) plane exhibits the highest order, followed by the (111) plane, with the (110) plane being the weakest. Notably, despite its highest atomic density in the first-ordered layer, the (111) substrate suffers from lower atomic mobility than the (100) and (110) substrates, hindering rapid rearrangement into the FCC structure. The synergy of the layer-by-layer growth mode, strong templating efficiency, and high atomic mobility leads to the fastest crystal growth for the (100) orientation.

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