Effect of Samarium doping on the nucleation of fcc-Aluminum in undercooled liquids

TL;DR

This study uses molecular dynamics simulations to show that samarium doping significantly suppresses the nucleation rate of fcc-Aluminum in undercooled liquids, primarily by increasing the free energy barrier.

Contribution

It introduces a systematic analysis of Sm doping effects on Al nucleation rates using the persistent-embryo method in molecular dynamics simulations.

Findings

Sm doping reduces nucleation rate by up to 25 orders of magnitude at 5% concentration.

The main effect of Sm is increasing the free energy barrier for nucleation.

Minor contribution from suppression of atom attachment to the nucleus.

Abstract

The effect of Sm doping on the fcc-Al nucleation was investigated in Al-Sm liquids with low Sm concentrations (xSm) with molecular dynamics simulations. The nucleation in the moderately undercooled liquid is achieved by the recently developed persistent-embryo method. Systematically computing the nucleation rate with different xSm (xSm=0%, 1%, 2%, 3%, 5%) at 700 K, we found Sm dopant reduces the nucleation rate by up to 25 orders of magnitudes with only 5% doping concentration. This effect is mostly associated with the increase in the free energy barrier with a minor contribution from suppression of the attachment to the nucleus caused by Sm doping.