First principles calculation of interfacial stability, energy, and elemental diffusional stability of Fe (111)/Al2O3 (0001) interface

First-principles calculation is widely used to study solid-solid interfaces, which provides insights into the atomic and electronic structure of an interface including the interfacial stability and adhesion strength. In general, the interface of the Fe/Al2O3 composite material is hardly wetted, and the aluminum oxide layer is firm and thin. It is difficult to observe the interface via an electron microscope. Thus, the changes at the interface were studied by first-principles calculations. Interfacial stability, energy of the Fe (111) surface, the Al2O3 (0001) surface, and Fe (111)/Al2O3 (0001) interfaces were studied using the first-principles calculation method. The work of adhesion (Wad), interface energy (γint), and the electronic structure of Fe (111)/Al2O3 (0001) interfaces were studied. The results indicated that Wad of the O-terminated interface was significantly larger than that of the Al-terminated interface. The O-terminated interface was the most stable interface. Furthermore, the O-terminated interface consisted of strong polar covalent bonds and weak metallic bonds, while the Al-terminated interface primarily consisted of covalent and metallic bonds. Furthermore, the segregation of Al atoms at the interface enhanced the stability of the interface structure, and interfacial bonding ability was increased with the increase in aluminum atoms. Only aluminum atoms diffused through the initial oxide layer forming intermetallic compounds on the iron side. The inclusion of Al2O3 significantly impacts the mechanical properties of steel, such as toughness and fatigue, underscoring that it is important to predict and control the inclusions in steel to obtain desired mechanical properties. The insights obtained from the study described here provide fundamental insights and guidelines into tailoring the steel/aluminum composite interface.