Atom-probe tomography of surface oxides and oxidized grain boundaries in alloys from nuclear reactors

ABSTRACTThe preparation of site-specific atom-probe tomography (APT) samples containing localized features has become possible with the use of focused ion beams (FIBs). This technique was used to achieve the analysis of surface oxides and oxidized grain boundaries in this paper. Transmission electron microscopy (TEM), providing microstructural and chemical characterization of the same features, has also been used, revealing crucial additional information.The study of grain boundary oxidation in stainless steels and nickel-based alloys is required in order to understand the mechanisms controlling stress corrosion cracking in nuclear reactors. Samples oxidized under simulated pressurized water reactor primary water conditions were used, and FIB lift-out TEM and APT specimens containing the same oxidized grain boundary were prepared and fully characterized. The results from both techniques were found fully consistent and complementary.Chromium-rich spinel oxides grew at the surface and into the bulk material, along grain boundaries. Nickel was rejected from the oxides and accumulated ahead of the oxidation front. Lithium, which was present in small quantities in the aqueous environment during oxidation, was incorporated in the oxide. All phases were accurately quantified and the effect of different experimental parameters were analysed.

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Examinations of Oxidation and Sulfidation of Grain Boundaries in Alloy 600 Exposed to Simulated Pressurized Water Reactor Primary Water

Microscopy and Microanalysis ◽

10.1017/s1431927613000421 ◽

2013 ◽

Vol 19 (3) ◽

pp. 676-687 ◽

Cited By ~ 48

Author(s):

D.K. Schreiber ◽

M.J. Olszta ◽

D.W. Saxey ◽

K. Kruska ◽

K.L. Moore ◽

...

Keyword(s):

Electron Microscopy ◽

Grain Boundary ◽

Grain Boundaries ◽

Atom Probe Tomography ◽

Atom Probe ◽

Alloy 600 ◽

Pressurized Water Reactor ◽

Intergranular Attack ◽

Pressurized Water ◽

Primary Water

AbstractHigh-resolution characterizations of intergranular attack in alloy 600 (Ni-17Cr-9Fe) exposed to 325°C simulated pressurized water reactor primary water have been conducted using a combination of scanning electron microscopy, NanoSIMS, analytical transmission electron microscopy, and atom probe tomography. The intergranular attack exhibited a two-stage microstructure that consisted of continuous corrosion/oxidation to a depth of ~200 nm from the surface followed by discrete Cr-rich sulfides to a further depth of ~500 nm. The continuous oxidation region contained primarily nanocrystalline MO-structure oxide particles and ended at Ni-rich, Cr-depleted grain boundaries with spaced CrS precipitates. Three-dimensional characterization of the sulfidized region using site-specific atom probe tomography revealed extraordinary grain boundary composition changes, including total depletion of Cr across a several nm wide dealloyed zone as a result of grain boundary migration.

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A new approach to atomic level characterization of grain boundaries by atom probe tomography

MRS Proceedings ◽

10.1557/opl.2014.90 ◽

2014 ◽

Vol 1645 ◽

Cited By ~ 1

Author(s):

L. Yao ◽

M. K. Miller

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Atom Probe Tomography ◽

Ion Irradiation ◽

Atom Probe ◽

Heavy Ion ◽

Solute Segregation ◽

Full Description ◽

High Dose ◽

Ferritic Alloy

ABSTRACTA novel atom probe tomography (APT) method has been developed that enables a full description of the orientation relationship between individual grains to be determined together with estimates of the extents of solute segregation for all elements over the surface of the grain boundary with 1 nm by 1 nm spatial resolution. This approach also enables variations in the solute excess for the elements with the habit plane and curvature of the grain boundary to be evaluated. The method has been applied to a mechanically-alloyed nanostructured ferritic alloy (NFA) after high dose heavy ion irradiation. The innovative high-resolution two-dimensional mapping of the solute segregation across the surface of grain boundaries in the NFA clearly demonstrates that the distributions of chromium and tungsten are not uniform across the grain boundaries, and the distributions correlate with changes in its local curvature and the position of the grain boundary precipitates. These features pin the grain boundary against grain growth and provide the stability for excellent creep properties.

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Implementing Transmission Electron Backscatter Diffraction for Atom Probe Tomography

Microscopy and Microanalysis ◽

10.1017/s1431927616011296 ◽

2016 ◽

Vol 22 (3) ◽

pp. 583-588 ◽

Cited By ~ 18

Author(s):

Katherine P. Rice ◽

Yimeng Chen ◽

Ty J. Prosa ◽

David J. Larson

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Atom Probe Tomography ◽

Focused Ion Beam ◽

Electron Backscatter Diffraction ◽

Ion Beam ◽

Atom Probe ◽

Specimen Preparation ◽

Inconel 600 ◽

Transmission Electron

AbstractThere are advantages to performing transmission electron backscattering diffraction (tEBSD) in conjunction with focused ion beam-based specimen preparation for atom probe tomography (APT). Although tEBSD allows users to identify the position and character of grain boundaries, which can then be combined with APT to provide full chemical and orientation characterization of grain boundaries, tEBSD can also provide imaging information that improves the APT specimen preparation process by insuring proper placement of the targeted grain boundary within an APT specimen. In this report we discuss sample tilt angles, ion beam milling energies, and other considerations to optimize Kikuchi diffraction pattern quality for the APT specimen geometry. Coordinated specimen preparation and analysis of a grain boundary in a Ni-based Inconel 600 alloy is used to illustrate the approach revealing a 50° misorientation and trace element segregation to the grain boundary.

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Grain-boundary segregation of magnesium in doped cuprous oxide and impact on electrical transport properties

Scientific Reports ◽

10.1038/s41598-021-86969-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

João Resende ◽

Van-Son Nguyen ◽

Claudia Fleischmann ◽

Lorenzo Bottiglieri ◽

Stéphane Brochen ◽

...

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Cuprous Oxide ◽

Atom Probe Tomography ◽

Electrical Transport ◽

Chemical Vapour ◽

Boundary Segregation ◽

Atom Probe ◽

Organic Chemical ◽

Electrical Transport Properties

AbstractIn this study, we report the segregation of magnesium in the grain boundaries of magnesium-doped cuprous oxide (Cu2O:Mg) thin films as revealed by atom probe tomography and the consequences of the dopant presence on the temperature-dependent Hall effect properties. The incorporation of magnesium as a divalent cation was achieved by aerosol-assisted metal organic chemical vapour deposition, followed by thermal treatments under oxidizing conditions. We observe that, in comparison with intrinsic cuprous oxide, the electronic transport is improved in Cu2O:Mg with a reduction of resistivity to 13.3 ± 0.1 Ω cm, despite the reduction of hole mobility in the doped films, due to higher grain-boundary scattering. The Hall carrier concentration dependence with temperature showed the presence of an acceptor level associated with an ionization energy of 125 ± 9 meV, similar to the energy value of a large size impurity−vacancy complex. Atom probe tomography shows a magnesium incorporation of 5%, which is substantially present at the grain boundaries of the Cu2O.

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Micromechanical testing of oxidized grain boundaries in Nickel alloys from nuclear reactors

MRS Proceedings ◽

10.1557/opl.2013.40 ◽

2013 ◽

Vol 1519 ◽

Cited By ~ 2

Author(s):

Sergio Lozano-Perez ◽

Helen Dugdale ◽

David E J Armstrong ◽

Takumi Terachi ◽

Takuyo Yamada ◽

...

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Nickel Alloys ◽

Nuclear Reactors ◽

Pressurized Water ◽

Grain Boundary Plane ◽

Initiation And Propagation ◽

Primary Water ◽

Water Reactors

ABSTRACTThe fracture behaviour of individual grain boundaries has been studied in order to understand the mechanisms controlling stress corrosion cracking in nuclear reactors. In particular, the role of oxidation in facilitating crack initiation and propagation has been reviewed. Nickel alloys from pressurized water reactors (PWRs) have been tested in simulated primary water conditions to induce grain boundary oxidation. Microcantilevers containing an oxidized grain boundary plane have been prepared and tested for fracture. The brittle nature of the oxide was demonstrated and the required stress to fracture measured.

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Correlating Atom Probe Tomography with Atomic-Resolved Scanning Transmission Electron Microscopy: Example of Segregation at Silicon Grain Boundaries

Microscopy and Microanalysis ◽

10.1017/s1431927617000034 ◽

2017 ◽

Vol 23 (2) ◽

pp. 291-299 ◽

Cited By ~ 13

Author(s):

Andreas Stoffers ◽

Juri Barthel ◽

Christian H. Liebscher ◽

Baptiste Gault ◽

Oana Cojocaru-Mirédin ◽

...

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Grain Boundary ◽

Grain Boundaries ◽

Atom Probe Tomography ◽

Scanning Transmission Electron Microscopy ◽

Atom Probe ◽

Scanning Transmission Electron ◽

Transmission Electron ◽

Scanning Transmission

AbstractIn the course of a thorough investigation of the performance-structure-chemistry interdependency at silicon grain boundaries, we successfully developed a method to systematically correlate aberration-corrected scanning transmission electron microscopy and atom probe tomography. The correlative approach is conducted on individual APT and TEM specimens, with the option to perform both investigations on the same specimen in the future. In the present case of a Σ9 grain boundary, joint mapping of the atomistic details of the grain boundary topology, in conjunction with chemical decoration, enables a deeper understanding of the segregation of impurities observed at such grain boundaries.

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3D sub-nanometer analysis of glucose in an aqueous solution by cryo-atom probe tomography

Scientific Reports ◽

10.1038/s41598-021-90862-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

T. M. Schwarz ◽

C. A. Dietrich ◽

J. Ott ◽

E. M. Weikum ◽

R. Lawitzki ◽

...

Keyword(s):

Atom Probe Tomography ◽

Density Functional ◽

Chemical Characterization ◽

Analytical Techniques ◽

Atom Probe ◽

Characterization Methods ◽

Signal Deconvolution ◽

The Stability ◽

Frozen Solutions ◽

3D Volume

AbstractAtom Probe Tomography (APT) is currently a well-established technique to analyse the composition of solid materials including metals, semiconductors and ceramics with up to near-atomic resolution. Using an aqueous glucose solution, we now extended the technique to frozen solutions. While the mass signals of the common glucose fragments CxHy and CxOyHz overlap with (H2O)nH from water, we achieved stoichiometrically correct values via signal deconvolution. Density functional theory (DFT) calculations were performed to investigate the stability of the detected pyranose fragments. This paper demonstrates APT’s capabilities to achieve sub-nanometre resolution in tracing whole glucose molecules in a frozen solution by using cryogenic workflows. We use a solution of defined concentration to investigate the chemical resolution capabilities as a step toward the measurement of biological molecules. Due to the evaporation of nearly intact glucose molecules, their position within the measured 3D volume of the solution can be determined with sub-nanometre resolution. Our analyses take analytical techniques to a new level, since chemical characterization methods for cryogenically-frozen solutions or biological materials are limited.

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An atom probe tomography study of grain boundary segregation in nanocrystalline Ni-W

MRS Proceedings ◽

10.1557/proc-0903-z03-01 ◽

2005 ◽

Vol 903 ◽

Cited By ~ 2

Author(s):

Andrew Detor ◽

Michael K. Miller ◽

Christopher A. Schuh

Keyword(s):

Grain Boundary ◽

Atom Probe Tomography ◽

Boundary Segregation ◽

Atom Probe ◽

Solute Segregation ◽

Grain Boundary Segregation ◽

Distribution Analysis ◽

Grain Sizes ◽

Composition Fluctuations ◽

20 Nm

AbstractAtom probe tomography is used to observe the solute distribution in electrodeposited nanocrystalline Ni-W alloys with three different grain sizes (3, 10, and 20 nm) and the results are compared with atomistic computer simulations. The presence of grain boundary segregation is confirmed by detailed analysis of composition fluctuations in both experimental and simulated structures, and its extent quantified by a frequency distribution analysis. In contrast to other nanocrystalline alloys, the present Ni-W alloys exhibit only a subtle amount of solute segregation to the intergranular regions. This finding is consistent with quantitative predictions for these alloys based upon a thermodynamic model of grain boundary segregation.

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