Molecular dynamics simulations of the structural properties of Al2O3-based binary systems

•The structure properties of Al2O3-based binary systems were carried out via molecular dynamics simulation.•The systematic effects of cation field strength of the metal cations on the melt structure were studied.•Comparisons were done between simulation results and experimental values.

In order to aid the research and development of Al2O3-based mold fluxes, a comprehensive study of the structural properties of Al2O3-based binary systems was carried out via molecular dynamics simulations. The simulation results demonstrated that the structural properties of Al2O3-based binary systems varied with both the Al3 + content and the type of metal cation. The aluminate network becomes more complex with increasing Al2O3 content, and for a given Al2O3 content in different systems, both the Al–O structural disorder and the polymerization degree of the network structure increase as the metal cations become more electronegative. For a given Al2O3 content, the effects of the components on stabilizing the Al–O network is sequenced as K2O > Na2O > CaO > MgO, and the polymerization degree of the structure in different systems follows the order K2O–Al2O3 < Na2O–Al2O3 < CaO–Al2O3 < MgO–Al2O3. In addition, both the metal cations and the oxygen triclusters play a role in the charge compensation of the AlO4 tetrahedron.