Microstructure evolution and properties of liquid Fe–P with different phosphorus content: molecular dynamic investigation

Context

With the scarcity of high-quality iron ore, high-phosphorus ores have become increasingly prevalent, posing challenges to maintaining the quality of steel. Phosphorus has emerged as a key factor affecting the fluidity of molten iron and the quality of steel products. Therefore, molecular dynamics method was conducted to analyze phosphorus’s impact on the microstructure and properties of liquid iron. The research examined phosphorus contents of 1 mol%, 3 mol%, 5 mol%, and 7 mol%, focusing on parameters like radial distribution functions, coordination numbers, and mean square displacements. Results showed that phosphorus decreases the viscosity, disrupts Fe–Fe bonds, and increases the self-diffusion coefficients of both Fe and P atoms. Microstructural analysis revealed phosphorus’s role in forming complex clusters, affecting the liquid iron’s local structural order. This research provides a deeper understanding of phosphorus behavior in liquid iron, offering insights for optimizing impurity control in ironmaking and enhancing the quality of steel products.

Method

Lammps software was conducted to do the molecular dynamics simulation using EAM potential with NVT ensemble at 1873 K. The research subject is Fe–P melts. The initial state model is created by randomly substituting Fe atoms in the iron crystal with P atoms based on the specific number of P atoms. The ISAACS software was used to analyze the trajectories of the Fe–P melt, including structural factors, radial distribution functions, coordination numbers, bond lengths, bond angles, and microscopic clusters. Additionally, mean square displacement and atomic diffusion coefficients are analyzed. The calculated viscosity is compared with experimental data from published literature.