4th International Congress on 3D Materials Science (3DMS) 2018: New Experimental and Analysis Methods III
Program Organizers: Hugh Simons, Denmark Technical University; Henning Poulsen, Denmark Technical University; David Rowenhorst, Naval Research Laboratory; Peter Voorhees, Northwestern University; Satoshi Hata, Kyushu Univ; McLean Echlin, UC Santa Barbara

Wednesday 10:20 AM
June 13, 2018
Room: Store Scene
Location: Kulturværftet (Culture Yard) Conference Center

Session Chair: Jun Yamasaki, Osaka University

10:20 AM  Invited
A New End Station at the Materials Science Beamline at the ESRF: Jon Wright1; Marta Majkut1; Pavel Sedmak1; Carlotta Giacobbe1; Wolfgang Ludwig1; Thomas Buslaps1; Henri Gleyzolle1; Ludovic Ducotte1; 1ESRF
     A new end-station for high-energy X-ray nanofocus measurements has been installed at the ID11 beamline at the ESRF. The instrument offers beam sizes in the range 100nm – 1 micron and has a diffractometer that can align and maintain samples in the X-ray beam during rotation. The instrument offers a full suite of single crystal, powder, PDF and grain mapping measurement options. XRD-CT data collection is accessible with relatively high frames rates (>25 fps) and 2D slices can be stacked to get a 3D view of the sample. The instrument has completed user experiments in various scientific areas already, including metallurgy, ceramics, chemistry and geology. Existing software has been adapted to allow reconstruction of the spotty XRD-CT data. We will discuss some of the scientific highlights from this new end-station and future perspectives in the light of the forthcoming ESRF source upgrade.

10:50 AM  
Identifying and Quantifying Anomalies and Rare Events in Large Volume 3D Polycrystalline Aggregates: Sean Donegan1; Michael Uchic1; Michael Groeber1; Michael Chapman2; Adam Pilchak1; 1Air Force Research Laboratory; 2UES, Inc.
    Understanding the behavior of anomalies and rare events in polycrystalline aggregates is important for predicting macroscale behavior in many materials systems. Statistical analysis of such outlier features usually lacks predictive merit due to small characterization volumes coupled with the rarity of the interesting events. Recent advances using polarized light microscopy and serial sectioning allow for the characterization of large-volume 3D data sets in optically anisotropic materials. This data collection pipeline, described in detail in a complementary submission to the congress, enables the characterization of more than 100,000 unbiased grains in a single phase alpha titanium alloy, offering unique opportunities for exploring outlier features in a polycrystalline structure. We present several statistical techniques from extreme value theory for quantifying outliers in microstructure feature distributions, such as grain size and morphology. Additionally, we highlight the advantages of a monolithic 3D data set, including the use of sub-sampling for cross-validation of statistical models.

11:10 AM  
Efficient Pathways for 3D Characterization of Rarely-occurring Features in Polycrystalline Ensembles: Michael Uchic1; Michael Chapman2; Sean Donegan1; Michael Groeber1; Adam Pilchak1; 1Air Force Research Laboratory; 2UES, Inc
    Characterization of rarely-occurring features in 3D polycrystalline ensembles is a generally unexplored topic, in large part because of the current difficulty in collecting experimental datasets that allow for meaningful statistical analysis. The recent development of computationally-controlled polarized light imaging—which was presented at 3DMS 2016—has enabled more efficient data collection protocols to gather both grain morphology and some aspects of crystallographic orientation in optically-anisotropic metals such as titanium. This study presents the combined use of this technology with mechanical polishing-based serial sectioning instrumentation to produce 3D data sets from single phase alpha titanium samples that contain more than 100,000 unbiased grains. We present key aspects of the data collection and post-processing pipeline that enable a fully-automated workflow, and, highlight results of the analysis of the tails of the grain size distribution using extreme value theory, which is described in detail in a complementary submission for this congress.

11:30 AM  
Non-linear Iterative Methods for Direct 3D Phase-retrieval and Tomographic Inversion of Coherent Diffraction Patterns: Tiago Ramos1; Martin Andersen1; Jens Andreasen1; 1Technical University of Denmark
     Coherent X-ray diffractive imaging methods provide quantitative measurements of the sample complex refractive index with spatial resolutions on the order of tens of nanometres, high degree of penetration and minimal sample preparation when compared, for example, with electron microscopy techniques.Data processing and tomographic reconstruction from coherent diffraction data is often performed in three steps: phase-retrieval, tomographic alignment and tomographic reconstruction. We present a combined three-dimensional non-linear numerical algorithm for a direct inversion and tomographic reconstruction of far-field coherent diffraction patterns. The implementation of our algorithm allows a full flexible description of the experimental setup, generalizing its application to full-field (holography/CDI) or to scanning (ptychography) geometries, where all geometrical degrees of freedom can be defined by the user. We demonstrate the behaviour, convergence and results of our algorithm applied to simulated data, and identify the advantages of this novel reconstruction method in terms of data acquisition and data analysis.

11:50 AM  
X-ray Diffraction Contrast Tomography and Applications to 3D Materials Science: Wolfgang Ludwig1; Nicola Vigano2; 1Université de Lyon; 2Centrun Wiskunde Informatica
    X-ray diffraction contrast tomography is a fast orientation mapping technique applicable to a variety of polycrystalline materials. Spatially resolved orientation maps are reconstructed on a grain by grain basis using an iterative 6D optimization scheme. Recent extensions of the model include a number of physical corrections (detector point spread, beam profile, attenuation) and improved handling of simultaneous reconstruction of orientation related domains. We will showcase the current possibilities and limitations on a series of selected application examples covering in-situ studies of recrystallization, grain growth, plastic deformation and phase transformations.