Molecular Dynamics Simulation and Thermodynamic Calculation on the Effects of w(Al2O3)/w(SiO2) and w(MgO)/w(Al2O3) Ratios on Microstructure and Properties of High‐Carbon Ferrochrome Slag

The MgO–Al 2 O 3 –SiO 2 –10wt%CaO system is a crucial slag system for high‐carbon ferrochrome (HCFeCr). The slag has high MgO and Al 2 O 3 characteristics (22–33 wt%), with a typical liquidus temperature of ≈1650–1750 °C for HCFeCr slag. Understanding the microstructure and thermodynamic properties of this system is critically important for HCFeCr production. This study investigates the effects of w(Al 2 O 3 )/w(SiO 2 ) and w(MgO)/w(Al 2 O 3 ) ratios on the microstructure and properties of the system using molecular dynamics simulations combined with FactSage. The results demonstrate that Si 4+ ions predominantly form [SiO 4 ] 4− tetrahedral structures, while Al 3+ ions mainly exist as [AlO 4 ] 5− tetrahedrons. As the w(Al 2 O 3 )/w(SiO 2 ) increases from 0.7 to 1.1, the degree of polymerization (DOP) of the slag increases. At a w(Al 2 O 3 )/w(SiO 2 ) ratio of 1.0, Al 2 O 3 exhibits basic characteristics, disrupting the SiOAl structure and slowing the upward trend in polymerization. As the w(MgO)/w(Al 2 O 3 ) increases from 0.8 to 1.5, more Mg 2+ ions act as network modifiers, promoting the dissociation of three‐coordinated and bridging oxygen into non‐bridging and free oxygen, thereby reducing the DOP. Furthermore, the w(Al 2 O 3 )/w(SiO 2 ) ratio has a greater influence on the system's enthalpy and liquidus temperature than the w(MgO)/w(Al 2 O 3 ) ratio.