Energetics and diffusion of hydrogen in hydrogen permeation barrier of α-Al2O3/FeAl with two different interfaces

• Published in: International journal of hydrogen energy Vol. 38; no. 18; pp. 7550 - 7560
• Main Authors: Zhang, Guikai, Wang, Xiaolin, Yang, Feilong, Shi, Yan, Song, Jiangfeng, Lai, Xinchun
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 18.06.2013; Elsevier
• Subjects: Alternative fuels. Production and utilization; Aluminides; Aluminum; Applied sciences; DFT; Diffusion barriers; Energy; Exact sciences and technology; FeAl; Ferrous alloys; Fuels; Hydrogen; Hydrogen diffusion; Hydrogen permeation barrier; Interface; Intermetallic compounds; Intermetallics; Iron aluminides; Iron compounds; Slabs; α-Al2O3; Hydrogen diffusion; DFT; FeAl; Interface; α-Al2O3; Hydrogen permeation barrier; Hydrogen; α-Al; O
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2013.03.136

To provide insights into the interface structure of hydrogen permeation barrier of α-Al2O3/FeAl and its effect on stability and diffusion of hydrogen isotopes, the thermodynamics and kinetics of H diffusion in α-Al2O3 (001)/FeAl (111) slab with Al/O and Al/Fe/O interfaces have been studied by the density functional theory. Hexagonal alumina layers above the FeAl plane in interface region are predicted. The interfacial binding involves cation–anion and metal–metal interactions. H-surface interaction on the α-Al2O3/FeAl slab resembles that on pure α-Al2O3 (001) slab, and the H interstitials in the α-Al2O3 part of the slab with the Al/O interface are significantly less stable than in bulk of α-Al2O3 slab, whereas that with the Al/Fe/O interface are slightly more stable. H diffusion into the α-Al2O3 part of both slabs must overcome a larger barrier of about 1.66–2.02 eV at surface-to-subsurface step, as pure α-Al2O3 case. For the bulk path, the migration of H atom can occur more readily in the α-Al2O3 part of the slab with the Al/O interface compared to that with the Al/Fe/O interface. Thus α-Al2O3/FeAl barrier with interface region of the Al, Fe mix-oxide is predicted to be much effective at protection against H permeation of the underlying steel. •Hexagonal alumina layers above the FeAl plane in interface regions are observed.•Bond characters of interface involve cation–anion and metal–metal interactions.•H-surface interaction on α-Al2O3/FeAl slab resembles that on pure α-Al2O3.•Interaction between α-Al2O3 and FeAl suppresses H atom mobility in the α-Al2O3 part.•α-Al2O3/FeAl with Al/Fe/O interface is much effective at reduction of H permeation.