Atom Probe Tomography for Advanced Characterization of Metals, Minerals and Materials III: General Methods and Development
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division, TMS: Nuclear Materials Committee, TMS: Phase Transformations Committee
Program Organizers: Haiming Wen, Missouri University of Science and Technology; David Seidman, Northwestern University; Keith Knipling, Naval Research Laboratory; Gregory Thompson, University of Alabama; Simon Ringer, University of Sydney; Arun Devaraj, Pacific Northwest National Laboratory; Gang Sha, Nanjing University of Science and Technology
Wednesday 8:30 AM
February 26, 2020
Room: Theater A-1
Location: San Diego Convention Ctr
Session Chair: David Seidman, Northwestern University; Haiming Wen, Missouri University of Science and Technology
8:30 AM Invited
A Review of Atom Probe Tomography Technology: The Present and Future: David Larson1; 1CAMECA Instruments Inc.
Over the past decade, the improvements in the capability of 3D nanoscale characterization using atom probe tomography (APT) have been remarkable. The advances have enabled analysis of material systems and structures far beyond the early limitations of APT to bulk metals. In addition, the maturation of FIB-based specimen preparation methods and the use of in-situ t-EBSD/STEM has made site-specific analyses truly routine. This presentation will provide an overview of the state-of-the-art hardware, software, and applications with a perspective on the performance needs of various selected applications.
9:00 AM Invited
APT for Atomic-scale Insights to the Origins of Materials Properties: Michael Moody1; Paul Bagot1; Tom Lapington1; David Tweddle1; Benjamin Jenkins1; 1University of Oxford
Increasingly, across a wide-range of material research problems, further advances in material performance now requires understanding of microstructure at the atomic scale. APT routinely provides unique insight into 3D chemical distributions within materials at a scale that even the most advanced electron microscopes cannot routinely achieve. This presentation will highlight three examples where critical nanoscale information provided by APT can be directly correlated to properties to support the further design of material composition and processing and thereby optimise performance. This includes: the evolution of solute clusters in the microstructure of steels designed as components for fission reactors; electrical properties of gettered/passivated multi-crystalline silicon; and oxidation performance of a series of Ni-based superalloys systematically varying in Ti and Nb content.
9:30 AM Cancelled
Atom Probe Characterisation of Hydrogen in Iron and Steels: Peter Felfer1; Valentin Dalbauer1; 1Fau Erlangen-Nurnberg
It has been long known that ingress of H into iron-based materials leads to a significant lowering in strength and ductility. The mechanisms behind it however are still only partly understood. While this problem has been of great commercial interest for decades, it has recently gained even more significance as steels are needed for H infrastructure and H-based mobility. Here, especially the reduction in fatigue life is of interest. Since this can most likely be attributed to the interaction of H with crystal defects including dislocations and grain boundaries, it is of high importance to understand the energetics of the H – defect interaction. In this talk, we will present in-situ atom probe experiments where we use Deuterium measure the interaction energetics. We will also show first experiments performed on a custom-made atom probe with a titanium main chamber, allowing to perform direct analysis without D as an isotopic tracer.
10:00 AM Break
10:15 AM Invited
Nanoparticle Sample Preparation for Atom Probe Tomography: Chemical Fixation and Cryo-Fixation: Leigh Stephenson1; Se-Ho Kim1; Joohyun Lim1; Olga Kasian2; Pyuck-Pa Choi3; Christina Scheu1; Dierk Raabe1; Baptiste Gault1; 1Max Planck Institut Iron & Steel Research; 2Helmholtz Zentrum Berlin; 3KAIST
Controlling size, shape, and composition of nanoparticles is required to improve their physical properties. Dopants and impurities distribution may affect lattice strains, electronic band structure and eventually catalytic selectivity and activity of nanoparticles; therefore, three-dimensional sub-nanometer resolution elemental mapping is key. Atom probe tomography (APT) is an enabling characterization tool for mapping the elemental distribution in nanostructured materials due to its unique combination of three-dimensional (3D) capability, sub-nanometer spatial resolution, and ppm-level detection sensitivity. Herein, we discuss the development of specimens preparation techniques for freestanding nanoparticles using chemical fixation and cryo-fixation of TiO2 nanorods, MoS2 nanosheet, and Ag nanoparticle. Both methods developed yield reliable APT data for complex-structural nanoparticles and each fixation advantage and drawback will be discussed.
10:45 AM Invited
Compositional Dependencies of Ni- and Fe-oxides to Experimental Parameters in Atom Probe Tomography: Daniel Schreiber1; Ann Chiaramonti2; Karen Kruska1; 1Pacific Northwest National Laboratory; 2National Institute of Standards and Technology
High-temperature oxidation of metals leads to a complex, 3D menagerie of nanoscopic oxides that can be analyzed successfully and uniquely by atom probe tomography (APT). The identities of these oxide phases can, in principle, be determined by their local composition (i.e. the concentration of oxygen and the ratios of specific cations). Phase identification is critical to revealing the dynamic oxidation processes, but the presence of unexpected and non-stoichiometric phases impedes facile analyses. Furthermore, APT analyses are prone to erroneous O quantification which is not fully understood. In this work, we present systematic analyses of bulk Ni and Fe oxides (NiO, FeO, Fe2O3, Fe3O4 and NiFe2O4) to gain a better understanding of the consistency and error associated with the compositional measurements. New insights into the field evaporation behavior of these metal oxides will also be discussed to suggest general operational parameters and limitations of APT oxide characterization.
11:15 AM Invited
Morphological Classification of Dense Objects in Atom Probe Tomography Data: Iman Ghamarian1; Emmanuelle Marquis1; 1University of Michigan
Atom probe tomography (APT) is used for quantifying solute clusters and their interactions with defects in many alloy systems. Reliable quantification is essential to link these microstructural features and their evolution to materials properties. However, existing methods, i.e. the maximum separation method, only applies to limited microstructures and are highly dependent on user input. In an effort to develop reliable and statistical analysis methods, we explored the use of hierarchical density-based cluster analysis methods. We successfully applied it to complex microstructures. This approach is less dependent on subjective selection of parameters and exhibit significantly more accurate performance than the traditionally used maximum separation method. We also integrated an integrated density-based cluster analysis method and skeleton extraction to find dislocation loops/lines in APT data. We will provide a demonstration of the openly available interface on simulated and experimentally acquired datasets.
11:45 AM
Quantifying Compositional Uncertainty Arising from Peak Overlaps: Andrew London1; 1UK Atomic Energy Authority
There are many sources of error atom probe composition quantification, including when mass peaks overlap. A degree of difficulty and hence error in solving overlaps stems from their relative intensities. We show how uncertainty can be minimized using a maximum likelihood methodology, which furthermore yields a quantitative description of "overlap difficulty". Misidentification of peaks, often yields large systematic errors, which can be additionally complicated by overlapping peaks. However, an analyst must select only the set of ions that are reasonable to consider before solving the overlap. By using an objective criterion from information theory, it is shown how such systematic bias can be avoided when choosing which ions to consider when analyzing the mass spectrum. We show how combining these techniques improves compositional certainty and how this approach can improve experimental planning.
12:05 PM Cancelled
Post-morten Selected Area Analysis for Optimized Statistical Analysis of APT Data: Frederic Danoix1; Alexander Dahlstrom2; Begonia Gomez Ferrer3; Cristelle Pareige3; 1Cnrs; 2KTH Royal Institute of Technology; 3Normandy University
Latest generation of instruments allows atom probe analysis with wide angular apertures that most of the low index directions are included in the analysed volumes. For a decade now, many efforts have been devoted to retreive, at least partly, the cristallographic informations contained in the analysed volumes, either for assessing the analysed cristal(s) orientation(s), or to correlate it with nanostructural features present in the reconstructed volume. However, little attention has been drawn to investigate, in a given sample, the possible local artefacts araising from the presence of low index poles, and ultimately find the optimal regions for optimized data processing. Here, we present such investigations showing the potential for ‘post-morten selected area analysis’ of APT datasets in the cases of phase separation in FeCr alloys, and tracking long range order in metallic alloys.