Impact of la on steel inclusions: a first-principles investigation into elastic properties and anisotropy

Abstract

Abstract This study employed first-principles calculations based on density functional theory to explore the La-induced modifications in the elastic properties of inclusions at the microscopic level. Initially, through formation energy calculations, stable La2O3, La2O2S, and LaAlO3 inclusions were identified after the treatment with the rare earth element La. Subsequently, the elastic moduli and anisotropy of both the steel matrix and the inclusions were computed. The results revealed a substantial difference in the average elastic moduli between the common inclusions MnS, Al2O3 and the steel matrix, indicating their non-ductile nature. Conversely, La-modified inclusions, such as La2O2S and LaAlO3, exhibited closer average elastic moduli to the steel matrix with reduced anisotropy, mitigating stress concentration. This elucidates one of the reasons behind the enhanced fatigue performance of La-doped steel.