First-Principles Calculation of CaO–Al2O3–CaF2 Slag

To guide the development of CaO–Al 2 O 3 -based non-reactive mold flux for low-density high-strength steel production, CaO–Al 2 O 3 –CaF 2 slags were calculated by first-principles molecular dynamics. The results showed that the stability order of corresponding bonds was Al–O > Ca–F > Ca–O > Al–F. With F − addition, the stability of Al–O and Al–F bonds enhanced, and that of Ca–O bond decreased while Ca–F bond almost did not change. Furthermore, although lower CaO/Al 2 O 3 ratio increased the structure complex, the depolymerization and dilution of F played a dominant role to reduce the viscosity. Al–O and Al–F were charge-transfer bond, while Ca–O and Ca–F were ionic bond. The unstable hexahedron AlO 4 F evolved into tetrahedral AlO 3 F and AlO 4 dynamically. In addition, the low content of F mainly formed AlO 3 F structure to depolymerize and stabilize the Al–O network structure, while the high content of F promoted AlO 4 F structure to reduce the symmetry and stability of slag.