Assessment of the classical nucleation theory in supercooled nickel by molecular dynamics

LGV Goncalves and JPB de Souza and ED Zanotto, MATERIALS CHEMISTRY AND PHYSICS, 272, 125011 (2021).

DOI: 10.1016/j.matchemphys.2021.125011

In this work, we performed a thorough study of crystal nucleation rates in supercooled liquid (SCL) nickel by comparing molecular dynamics (MD) simulation results, theoretical calculations, and experimental data. Our aim was to assess the validity of the most used theoretical framework, the Classical Nucleation Theory (CNT), in describing homogeneous nucleation in a deeply supercooled liquid. To this end, we carried out MD simulations using an embedded atom interaction potential, which describes quite well the melting point, Tm, the enthalpy of fusion, Delta h, and the liquid density, rho l, of our model material. We then determined the critical nucleus size and the diffusion coefficient in the temperature range from 0.68 to 0.80Tm. By combining the physical properties obtained from our MD simulations and the calculated crystal- liquid free energy difference, we compared the CNT predictions with the nucleation rates obtained directly via brute force MD simulations on a system with 4 million atoms. We found an excellent agreement between the theoretically calculated nucleation rates and the values obtained by MD simulations. Moreover, the CNT prediction for the nucleation rate agrees with experimental data at 1350 K. Our results confirm that the CNT is indeed a powerful tool to describe the nucleation kinetics in supercooled liquids.

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