Modification of Al2O3 inclusions by cerium in steel: mechanism at atomic scale and kinetic analysis
摘要
To mitigate the harmful effects of Al2O3 inclusions in steel, it is necessary to conduct comprehensive research on the mechanisms and kinetic laws of Al2O3 inclusion modification by Ce. Combined with laboratory experiments, first-principles calculations, and molecular dynamics simulations, the kinetic model of Ce modification for Al2O3 inclusions was established. Based on first-principles calculations, differential charge analysis, density of states analysis, and adsorption energy analysis were performed on the transformation process from Al2O3 to CeAlO3 at the atomic scale, and the microscopic transformation mechanism of inclusions at the atomic scale was obtained. Molecular dynamics simulations and the solution of mean square displacement function show that the diffusion coefficient for Ce atoms was 2.169 × 10−4 cm2/s, which agreed well with experimental results. In this model, the rate-determining step is the diffusion of Ce atoms across Ce–Al–O inclusions. The relationship between the conversion rate, refining time, and initial radius was discussed. A refining time of 60 s can completely transform Al2O3 inclusions less than 2.56 μm into CeAlO3 inclusions, while refining time of 1200 s is sufficient to modify inclusions size below 11.47 μm.