First-principles calculation on γ-Fe/La2O3 interface properties and austenite refinement mechanism by La2O3.

In this paper, the interface properties and interfacial interaction were calculated by the first principle method, and the growth of γ-Fe boundary was inhibited by La 2 O 3 so as to refine the austenite grain was also analyzed. The calculated results show that the two-dimensional lattice mismatch between γ-Fe(110) plane and La 2 O 3 (001) plane is 8.7%. Therefore, the nucleation interface between γ-Fe and La 2 O 3 is most likely γ-Fe(110)/La 2 O 3 (001). Meanwhile, there are three kinds of interface models, which are Fe–La-OT, Fe–La-OM and Fe–La-Bridge, respectively. The interface adhesion work of Fe–La-OT interface is smallest, which is −0.10 J/m2, while, that of Fe–La-OM interface is largest, which is −0.02 J/m2. The ideal interface adhesion work of the three interfaces is negative, which indicates that they cannot be existed stably. The three kinds of interfacial chemical bonds are composed of ionic bonds and metallic bonds. The chemical bond polarity of Fe–La-OT interface is the strongest, and the metallic property of Fe–La-OM interface and Fe–La-Bridge interface is stronger than that of Fe–La-OT one. In addition, most interfacial interaction forces of the three interface models are repulsive, which indicates that La 2 O 3 has a good inhibitory effect on the growth interface of γ-Fe. Therefore, La 2 O 3 can inhibit the growth of γ-Fe boundaries so as to refine the austenite grains. Image 1 • Work of adhesion and interfacial energy ofγ-Fe(110)/La 2 O 3 (001) interfaces were calculated. • Interfacial electronic structures between γ-Fe and La 2 O 3 were analyzed. • Interfacial bond characteristics were revealed by electron localization function and interface DOS. • The mechanism that the La 2 O 3 refine the austenite grain was analyzed. [ABSTRACT FROM AUTHOR]