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

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 μ, 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 μ for low index (100), (110), and (111) interfaces: μ₁₀₀ = 35.8 ± 22, μ₁₁₀ = 25.5 ± 1.6, and μ₁₁₁ = 24.1 ± 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.