A study on prenucleation and heterogeneous nucleation in liquid Pb on solid Al using molecular dynamics simulations

Area of Science:

• Materials Science
• Computational Materials Science
• Physical Chemistry

Background:

• Heterogeneous nucleation is critical in materials processing.
• Large lattice misfit between nucleant and substrate poses challenges.
• Existing models may not fully explain nucleation mechanisms in such systems.

Purpose of the Study:

• Investigate prenucleation and heterogeneous nucleation in liquid Pb/solid Al.
• Examine systems with significant lattice misfit.
• Elucidate atomistic mechanisms governing nucleation.

Main Methods:

• Molecular dynamics simulation.
• Analysis of prenucleation and nucleation stages.
• Investigation of interfacial structures and energies.

Main Results:

• Prenucleation observed at 600 K with formation of a 2D ordered structure at the interface.
• A coincidence site lattice (CSL) accommodates 18.2% lattice misfit, reducing it to 1.9%.
• CSL formation transforms the substrate into a potent nucleant, facilitating epitaxial growth.

Conclusions:

• CSL is an effective mechanism for accommodating large positive lattice misfit.
• Heterogeneous nucleation mechanisms depend on lattice misfit, not solely on misfit dislocations.
• This study provides new insights into the atomistic mechanisms of heterogeneous nucleation.