First-Principles Study on the Influence of Atomic Coordination on the Adhesion Strength and Stability of FeCr2O4/α-Fe Interface

Abstract

To investigate the effect of atomic coordination on the stability and adhesion strength of the FeCr₂O₄/α-Fe interface, four different interface models (O top-site, Cr top-site, Fe₁ top-site, and Fe₂ top-site) are developed based on first-principles density functional theory. The results indicate that the FeCr₂O₄/α-Fe interface primarily consists of Fe_me-O_ox mixed ionic-covalent bonds and Fe_me-Fe_ox metallic bonds, with the Fe_me-O_ox bonds dominating the interfacial adhesion strength. Compared with the Fe₂ top-site interface, the Fe₁ and Cr top-site interfaces exhibit low charge accumulation and longer Fe_me-O_ox bonds, which results in weaker Fe_me-O_ox bonding strength at the interface. The orbital hybridization between Fe and O atoms at the Fe₂ top-site interface is stronger than that at the Cr top-site interface, leading to greater structural stability for the Fe₂ top-site interface. These results could have practical significance for understanding the failure of the oxide film on ferritic heat exchangers.