Molecular dynamics study on the thermophysical properties of KCl-CaCl2-NaCl ternary salt for magnesium alloy smelting

Chloride salts are widely used in magnesium alloy casting due to the low melting point, low cost, and effective purification. To improve the flux refining, it is essential to understand the relation between the composition and thermophysical properties of the flux, which cannot be achieved by conventional experimental means. In this study, molecular dynamics methods were carried out to explore the effects of temperature and composition on the physical properties (density, shear viscosity, and melt structure) of a commonly used flux. The results indicated that the lowest density of KCl among the three salts (KCl, CaCl₂, and NaCl) was attributed to the low ionic potential of K⁺. The increase in the mean distance between the ions reduced the density of the system, weakening the deformation resistance and decreasing the shear viscosity. Therefore, Classical molecular dynamics represents a viable alternative to some high temperature, highly volatile, and corrosive experiments.