Hume-Rothery Award Symposium: Alloy Phase Chemistry at the Atomic Level - Opportunities and Challenges: Session I
Sponsored by: TMS Functional Materials Division, TMS Structural Materials Division, TMS: Alloy Phases Committee, TMS: Nuclear Materials Committee, TMS: Phase Transformations Committee
Program Organizers: Wei Xiong, University of Pittsburgh; Shuanglin Chen, CompuTherm LLC; Frederic Danoix, Université de Rouen; Indrajit Charit, University of Idaho

Monday 8:30 AM
February 27, 2017
Room: 31C
Location: San Diego Convention Ctr

Session Chair: Patrick Grant, University of Oxford; David Larson, CAMECA

8:30 AM Introductory Comments Given by Prof. Patrick Grant, Department Head of Materials Science, University of Oxford

8:40 AM  Keynote
The Role of Atom Probe Tomography in Decoding the Materials Genome: George Smith1; 1Oxford University
    The experimental technique of Atom Probe Tomography (APT) is unique in its capability to image and identify single atoms within solids and to establish their location with sub-nanometer precision. Iteration of this process enables the three-dimensional reconstruction of the nanoscale microstructure and chemistry of a wide range of materials. The mission and purpose of this work closely resembles the objectives of molecular biology. It involves taking materials apart at the atomic level in order to find out how they work, and then seeking ways to improve their design and assembly, in order to make them work better. This lecture will outline the successive stages of development of the APT method, and illustrate its breadth of application by reference to recent studies of metals and alloys, catalysts, semiconductors and photonic materials.

9:20 AM  Invited
Atomic-scale Analytical Tomography: Thomas Kelly1; 1CAMECA Instruments, Inc.
    Efforts are underway for achieving billion atom tomography with 100% of the atoms in real space and high spatial fidelity. This capability can be termed atomic-scale tomography (AST). The plan is to couple this with complete analytical characterization at the atomic scale in a single instrument which would be called atomic-scale analytical tomography (ASAT). ASAT will require coupling atom probe tomography with (scanning) transmission electron microscopy. The instrumental developments needed to reach AST include: trajectory corrections for precise atom placement and detecting 100% of the atoms without ambiguity in identity. Once these large data sets become available, computational materials engineering can be integrated into the characterization process. Atomic-scale structure may thus be coupled to atomic-scale properties and structure-properties relationships at the atomic-scale may be studied, predicted, and observed.

9:50 AM  
Unique Insights from the Correlated Combination of Atom Probe and Electron Tomography: Peter Wells1; Stephan Krämer1; Christian Oberdorfer2; Soupitak Pal1; Yuan Wu1; Takuya Yamamoto1; G. Odette1; 1UC Santa Barbara; 2Ohio State University
    Fusion reactors will require development of new alloys that can withstand extreme environments, including high temperatures and neutron displacement damage, and must also manage large amounts of He generated in neutron-alpha reactions. These challenging service conditions lead to microstructure changes on the nano-scale, such as precipitation or He bubble/void formation, that are often times at the limit of characterization techniques. Atom probe tomography (APT) provides high resolution compositional measurements that track changes in solute locations, such as precipitation and segregation, in what are intrinsically 3D tomographic reconstructions. TEM provides other information, such as crystal structures, and probes larger sampling volumes, but often only in 2D projections. Here we report on insight gained using a combination of APT and TEM tomography on the same sample volumes. The correlation of these methods not only provides unique understanding regarding nm-scale features and their associations, but also highlights artifacts associated with the individual techniques.

10:10 AM Break

10:30 AM  Invited
On the Amazing Role of Atom Probe Tomography in Nuclear Materials Research: Some Seminal Contributions and Opportunities for Developing a New Lab On a Chip Paradigm: G. Robert Odette1; Peter Wells1; Nicholas Cunningham2; Nathan Almirall1; 1University of California Santa Barbara; 2ATI
    It is a privilege to address this Alloy Phase Chemistry at the Atomic Level Hume-Rothery Symposium, honoring the lifetime achievements of Professor George Smith. I have long appreciated atom probe tomography (APT) for nm-scale, 3D-imaging microanalysis, in my case applied to nano-metallic precipitates in irradiated steels and nano-oxides in dispersion strengthened alloys. I have also long been a loyal APT skeptic, sometimes challenging the orthodoxy of the expert community. My journey greatly benefited from George’s wisdom, both as a world-class materials scientist and as the open-minded father of modern APT. George still sees APT as in progress. After briefly noting seminal APT contributions, I will focus on the enormous opportunities to develop a new cradle-to-death “lab on a chip paradigm” for nuclear materials research. This involves combining APT with other fine scale nanostructural probes, like the FIB, synchrotron x-rays and TEM, that are also closely integrated with atomistic modeling.

11:00 AM  Invited
Revisiting Field Ion Microscopy: Baptiste Gault1; Michal Dagan2; Shyam Katnagallu1; Frédéric De Geuser3; François Vurpillot4; Dierk Raabe1; Michael Moody2; 1Max-Planck-Institut für Eisenforschung GmbH; 2University of Oxford; 3CNRS, SIMAP; 4Normandie Université
     Atomic-scale microscopy and microanalysis fundamentally drive advances in basic and applied materials science, allowing for correlating materials and devices properties to their atomic structure and chemical composition. Atom probe tomography (APT) has risen in prominence over the past decades owing to its unique capacity for nanoscale characterisation of structural and functional materials. APT has stemmed from field ion microscopy (FIM), the first technique to enable the imaging of individual atoms as early as the 1950s. However, FIM is currently only rarely performed despite its true complementarity with APT. In this presentation, we will present a quick tour of what FIM has to bring to APT, from the fundamental aspects of the projection to advancing the understanding of atoms at the specimen surface under high electric field conditions, and, finally, full three-dimensional reconstruction, with true atomic resolution, of the crystalline lattice as well as structural defects.

11:30 AM  Invited
Quantification of Hydrogen using Atom Probe Tomography: Daniel Haley1; Yi-Sheng Chen1; Paul Bagot1; Michael Moody1; 1University of Oxford
    Nanoscale characterisation of hydrogen (H) is traditionally a challenging problem in materials science, but is a high priority problem. H embrittlement is associated with materials failure in commonly used metallic alloys, such as high-strength steels. H is often present at low concentrations in such materials, and thus any H signal is difficult to separate from the host matrix when using electron, neutron or X-ray radiation based characterisation methods. Subsequently, many normally valuable techniques are of little utility, limiting the ability of researchers to quantify the role of H in such embrittlement phenomena. Atom probe tomography, in conjunction with isotopic loading, has been shown to be a viable method for identification of H, albeit with previously strong limitations on data quality. We demonstrate new experimental methods to reliably detect hydrogen in metallic alloys, such as nano-precipitated ferritic steels, with a view to robust hydrogen quantification in three dimensions.