Revealing the atomic-scale structure and the fracture mechanism of the α-Al2O3/γ-Fe ceramic-metal interface

The ideal adhesion work (W-ad), tensile failure process, and electronic properties for gamma-Fe (111)/alpha-Al2O3 (0001) interface with Al-and O-terminated were systematically investigated by the first-principles calcu-lations based on density functional theory. The results showed that the Al-terminated interface with Hcp-site and the O-terminated interface with Hcp-site were the most stable structures in all types of Fe/Al2O3 interfaces. However, the W-ad of the Al-and O-terminated interface were 1.465 and 7.102 J/m(2), respectively, indicating that the bonding strength of the O-terminated interface was significantly stronger than that of the Al-terminated interface. Then the tensile test exhibited the critical strain of O-terminated was 9.5% higher than that of Al-terminated interface and the ideal tensile strength was 3.5-fold that of Al-terminated. Remarkably, the failure position of the Al-terminated Fe/Al2O3 interface occurred exactly at the interface, but that of the O-terminated Fe/Al2O3 interface occurred inside the Al2O3 phase. In-depth analysis of electronic structure showed that the behavior of electrons transfer and orbital hybridization occurred near the failure position during stretching, and electron depletion between atomic layers was a signal of fracture. Further, the minimum overlap population of chemical bonds causes fractures in advance when the tensile deformation reaches critical strain. Interestingly, the failure structure of O-terminated found that Fe and O form new atomic layers, and the behavior of bonding has occurred between the two atoms. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Based on density functional theory, the adhesion work, tensile failure, and electronic properties of gamma-Fe/alpha-Al2O3 interfaces with Al- and O-terminations were systematically investigated. The results showed that the O-terminated interface exhibited stronger bonding strength and tensile performance compared to the Al-terminated interface, with different failure positions.