Ferritic alloys are widely used interconnect materials for solid oxide fuel cells (SOFCs)at present. The Mn doped Fe-Cr alloy interconnects form two layers of Cr2 O3 and (Cr, Mn)3 O4 in the oxide film in service, which can effectively prevent the problems of insufficient high temperature oxidation resistance and the volatilization of Cr. And the diffusion of Mn atoms in Fe-Cr alloy is crucial to the formation of (Cr, Mn) 3 O4 layer, but its microscopic mechanism is still unclear. In this wrok, the possible diffusion pathways of Mn atoms on the surface and the hopping diffusion of Mn from the inside to the surface of the ferritic Fe-Cr alloy using first-principles based on density functional theory (DFT) were systematically investigated. The bulk model of perfect Fe-25%Cr alloy and the slab model of (110) surface are set up and optimized. The potential energy surface (PES) of Mn on the surface and the stable adsorption positions of Mn are calculated, while the possible pathways of Mn on the surface are found. Furthermore, we employ the nudged elastic band (NEB) method to calculate the energy barriers of different Mn diffusion pathways. The results present that the maximum energy barrier for the surface diffusion is about 0.191 eV, while it is 4.480 eV for the hopping diffusion. And the corresponding Mn diffusion coefficients versus temperature for different diffusion processes are obtained accordingly. Our results explain the microscopic mechanism of Mn hopping diffusion and the surface diffusion of ferritic Fe-Cr alloy from the atomic scale, and find that the hopping diffusion determines the Mn diffusion, which provides theoretical guidance of the ferritic Fe-Cr alloy for its future research and practical applications in SOFCs metallic interconnect. © 2023 Cailiao Daobaoshe/ Materials Review. All rights reserved.
