title: Direct observation of individual hydrogen atoms at trapping sites in a ferritic steel.
abstract: The design of atomic-scale microstructural traps to limit the diffusion of hydrogen is one key strategy in the development of hydrogen-embrittlement-resistant materials. In the case of bearing steels, an effective trapping mechanism may be the incorporation of finely dispersed V-Mo-Nb carbides in a ferrite matrix. First, we charged a ferritic steel with deuterium by means of electrolytic loading to achieve a high hydrogen concentration. We then immobilized it in the microstructure with a cryogenic transfer protocol before atom probe tomography (APT) analysis. Using APT, we show trapping of hydrogen within the core of these carbides with quantitative composition profiles. Furthermore, with this method the experiment can be feasibly replicated in any APT-equipped laboratory by using a simple cold chain.
authors.affiliation: Department of Materials, Oxford University, 16 Parks Road, Oxford OX1 3PH, UK.
authors.forename: Y-S
authors.identifier: 0000-0002-2607-4388
authors.initials: YS
authors.lastname: Chen
authors.affiliation: Department of Materials, Oxford University, 16 Parks Road, Oxford OX1 3PH, UK. daniel.haley@materials.ox.ac.uk.
authors.forename: D
authors.identifier: 0000-0001-9308-2620
authors.initials: D
authors.lastname: Haley
authors.affiliation: Scientific Center for Optical and Electron Microscopy, ETH Zürich, Auguste-Piccard-Hof 1, 8093 Zürich, Switzerland.
authors.forename: S S A
authors.identifier: 0000-0002-1170-4762
authors.initials: SS
authors.lastname: Gerstl
authors.affiliation: Department of Materials, Oxford University, 16 Parks Road, Oxford OX1 3PH, UK.
authors.forename: A J
authors.identifier: 0000-0001-6959-9849
authors.initials: AJ
authors.lastname: London
authors.affiliation: Department of Materials Science and Engineering, Sheffield University, Western Bank, Sheffield S10 2TN, UK.
authors.forename: F
authors.identifier: 0000-0003-0642-6996
authors.initials: F
authors.lastname: Sweeney
authors.affiliation: Scientific Center for Optical and Electron Microscopy, ETH Zürich, Auguste-Piccard-Hof 1, 8093 Zürich, Switzerland.|Centre for Microscopy and Microanalysis, Faculty of Science, University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: R A
authors.identifier: 0000-0003-2203-3674
authors.initials: RA
authors.lastname: Wepf
authors.affiliation: Department of Materials Science and Engineering, Sheffield University, Western Bank, Sheffield S10 2TN, UK.
authors.forename: W M
authors.identifier: 0000-0003-3898-0318
authors.initials: WM
authors.lastname: Rainforth
authors.affiliation: Department of Materials, Oxford University, 16 Parks Road, Oxford OX1 3PH, UK.
authors.forename: P A J
authors.identifier: 0000-0002-9102-6083
authors.initials: PA
authors.lastname: Bagot
authors.affiliation: Department of Materials, Oxford University, 16 Parks Road, Oxford OX1 3PH, UK.
authors.forename: M P
authors.identifier: 0000-0002-9256-0966
authors.initials: MP
authors.lastname: Moody