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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]

The first principles method was used to calculate the interface stability, interfacial electronic structure and bond characteristics of γ-Fe/CeO 2 heterogeneous nucleation interface. Meanwhile, The formation mechanism of (100)_γ-Fe/(111)_CeO 2 heterogeneous nucleation interface was also revealed. The calculation results show that the two dimensional lattice mismatch between (100)_γ-Fe and (111)_CeO 2 is 4.9%, which indicates that (100)_γ-Fe and (111)_CeO 2 satisfy the crystallographic condition for the formation of effective heterogeneous nucleation interface. There are two kinds of interface models, named as O1-Fe and O2-Fe. The stability of O1-Fe interface is the best and its interfacial energy is the lowest, which is 3.07 J/m2. The ideal interfacial adhesive strength of O2-Fe interface is the largest, which is 10.98 J/m2. The bond characteristics of the two interfaces are both mixtures of covalent bonds and ionic bonds. It reveals that (100)_γ-Fe and (111)_CeO 2 can form effective heterogeneous nucleation interfaces and O1-Fe interface model forms preferably during the heterogeneous nucleation beginning process. When the formation conditions meet the requirement for both interface structures, the adhesive strength of the O2-Fe interface is higher. Therefore, CeO 2 can act as effective heterogeneous nucleation substrate of γ-Fe to refine the austenite grains. Image 1 • Two dimensional lattice mismatch between (100)_γ-Fe/(111)_CeO 2 is 4.9%. • O1-Fe interface has the best stability and O2-Fe interface has the largest ideal bonding strength. • Interfacial bond characteristics are mixture of covalent bonds and ionic ones. • (100)_γ-Fe/(111)_CeO 2 heterogeneous nucleation interface formed preferably as O1-Fe type. [ABSTRACT FROM AUTHOR]