Atomic‐Scale Insights into High‐temperature Interfacial Interactions between Molten Al and MgO

Abstract The widespread use of MgO‐based refractories in high‐Al steelmaking is hindered by limited atomic‐level understanding of their interfacial reactions with molten Al. In this work, ab initio molecular dynamics (AIMD) simulations were employed to investigate the interactions between molten Al and MgO. Results reveal that MgO(111), with high surface energy and oxygen termination, exhibits the strongest reactivity, while MgO(001) shows superior structural stability. Surface defects on MgO(001) promote oxygen migration, and dissolved oxygen in Al enhances Al diffusion into the MgO lattice, accelerating interface degradation. Moreover, the interfacial interaction becomes increasingly intense with rising temperature. An in‐depth analysis of charge density difference and Bader charge highlights the synergistic effect of diffusion and electron transfer on interfacial interactions. The interaction energy quantitatively describes interface stability, while the initial binding energy offers predictive insight. Preferential exposure of MgO(001), minimized surface defects, and strict oxygen control in molten Al are proposed to mitigate interfacial reactions, offering guidance for advanced MgO refractory design in high‐Al steelmaking.