Role of point defects in hydrogen damage at α-Cr2O3/α-Fe2O3 (0001) interface

Point defects at the actual alpha-Cr2O3/alpha-Fe2O3 (0001) interface control the passive film's protective properties, and their interaction with hydrogen is a crucial factor, which determines whether possibility of hydrogen damage can be reduced or not. We study the role of point defects in hydrogen damage at alpha-Cr2O3/alpha-Fe2O3 (0001) interface using density functional theory. It is found that Cr vacancy and Fe vacancy at the interface trap H with the lowest binding energy -2.908 eV and -2.798 eV, respectively. The solute atoms such as Zn, Ni and Cu at the interface trap H with negative binding energies, in which the minimum binding energy is -1.603 eV for Cu doped interface with H. Alloying elements Al, Ti, V, Mn, Nb and Mo at the interface lead to positive H binding energies, meaning they could not trap H atom. These results confirm that Cr vacancy, Fe vacancy and alloying elements Ni, Cu, and Zn play significant roles in hydrogen damage at the interface of passive films, while alloying elements Mn, Mo, Ti, Nb, Al and V can weaken the possibility of hydrogen damage at the interface of passive films. Our findings provide guiding significance of choosing proper alloying elements to obtain hydrogen damage-resistant steels in industry. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.