Research on Viscosity and Self-diffusion Coefficient of Liquid Mg by Molecular Dynamics Simulation

As one of the most common metals in industrial applications, it is difficult to experimentally measure the viscosity and diffusion coefficient of liquid Mg due to its high-temperature activity. Therefore, based on molecular dynamics (MD) simulation experiments, mean square displacement (MSD) and velocity auto-correlation function (VACF) were used to calculate the self-diffusion coefficient, and stress auto-correlation function (SACF) was used to calculate the viscosity of the liquid Mg. The merit of MD simulation was fully utilized to extend the temperature range from above the melting point to the maximum undercooling, that is, extending to the entire temperature range of the metastable liquid. The objects calculated by MSD and VACF are position and velocity, respectively, and both are single particle characters and are averaged on time and space, and thus the convergence of MSD and VACF methods is better than that of SACF. Besides, the temperature dependence of the self-diffusion coefficient agrees Arrhenius formula well and accordingly the cativity energies are achieved as 30.05, 29.87 kJ/mol, respectively. Finally, an emprical formula, i.e. log η=−1.1+1 090/T, is also achieved to describe the temperature dependence of viscosity.