Kinetic coefficient of Ni solid-liquid interfaces from molecular-dynamics simulations

Abstract

The kinetics of isothermal crystallization and melting are studied for elemental Ni employing non-equilibrium molecular-dynamics simulations based on interatomic potentials of the embedded-atom-method form. These simulations form the basis for calculations of the magnitude and crystalline anisotropy of the kinetic coefficient $\ensuremath{\mu},$ defined as the constant of proportionality between interface velocity and undercooling. We obtain highly symmetric rates for crystallization and melting, from which we extract the following values of $\ensuremath{\mu}$ for low index ${100},$ ${110},$ and ${111}$ interfaces: ${\ensuremath{\mu}}_{100}=35.8\ifmmode\pm\else\textpm\fi{}22,$ ${\ensuremath{\mu}}_{110}=25.5\ifmmode\pm\else\textpm\fi{}1.6,$ and ${\ensuremath{\mu}}_{111}=24.1\ifmmode\pm\else\textpm\fi{}4.0$ in units of cm/s K. The results of the present study are discussed in the context of previous molecular-dynamics simulations for related systems, and kinetic models based upon transition-state and density-functional theories.