4th International Congress on 3D Materials Science (3DMS) 2018: Dislocations, Twins, Strain, and Plastic Deformation I
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
Monday 3:50 PM
June 11, 2018
Room: Store Scene
Location: Kulturvćrftet (Culture Yard) Conference Center
Session Chair: Paraskevas Kontis, Max-Planck-Institut für Eisenforschung GmbH
3:50 PM Invited
Intra-granular Strain Sensitivity in Near-field High Energy Diffraction Microscopy: Yufeng Shen1; He Liu1; Robert Suter1; 1Carnegie Mellon University
Near-field High Energy x-ray Diffraction Microscopy (nf-HEDM), a synchrotron-based, non-destructive, 3-D characterization technique, has been used to measure grain maps of various materials, from elemental metals to complex industrial alloys in states from pristine to significantly deformed (ex. 15% tensile extension). Voxel based forward modeling reconstructions demonstrate sensitivity to intra-grain orientation variations. Here, we demonstrate intra-grain elastic strain sensitivity based on the observation that, in some data sets, projected images of grains are split between different detector images; that is, strain states are distinguished through sensitivity to the sample rotation angle, omega, rather than through variations in scattering angle, two-theta. Such sensitivity offers unique opportunities for testing and developing theoretical and computational models of materials responses. This talk will discuss the level of strain sensitivity and the conditions under which this information can be extracted. Examples will include both simulated and experimental data.
3D Dislocation Structures in Experiment and Modeling and application to Zirconium: Gabor Ribarik1; Gyula Zilahi1; Éva Ódor1; Tamás Ungár1; 1Eotvos Lorand University
Dislocation structures are three dimensional (3D) and grain structures in polycrystalline materials are also 3D. There are two fundamental methods to determine the dislocation structure: Electron Microscopy (EM) and X-ray Line Profile Analysis (XLPA). EM gives visual and detailed information of the type of dislocations, however, the volume of inspection is often limited. XLPA provides larger averages and can provide better information about strains and stresses. X-ray powder diffraction, though a powerful method, gives averages over millions of grains which may be very different in the individual structures. Recent high angular resolution synchrotron experiments have been carried out on polycrystalline samples providing single crystal line profile analysis giving detailed information on Burgers vector population and dislocation densities in single grains of a large variety of materials. We shall discuss the basics of single grain XLPA in polycrystalline samples and attempt to correlate the experimental results with modeling by numerical simulations.
Development of an In-situ Straining and Time-resolved Electron Tomography Data Acquisition System: Satoshi Hata1; Shinsuke Miyazaki2; Takeshi Gondo3; Katsumi Kawamoto4; Noritaka Horii4; Kazuhisa Sato5; Hiromitsu Furukawa4; Hiroyuki Kudo6; Hiroya Miyazaki3; Mitsuhiro Murayama7; 1Kyushu University; 2Thermo Fisher Scientific; 3Mel-Build Corporation; 4System in Frontier Inc.; 5Osaka University; 6University of Tsukuba & JST-ERATO; 7Virginia Tech
We designed an integrated system using a straining-and-tomography specimen holder and newly developed software for specimen-straining and image-acquisition and then developed an experimental procedure for in-situ straining and time-resolved electron tomography (ET) data acquisition. The software for tilt-series dataset acquisition and 3D visualization was developed based on the commercially available ET software TEMography. We achieved time-resolved 3D visualization of nanometer-scale plastic deformation behavior in a Pb-Sn alloy sample, which demonstrates the capability of this system for potential applications in 3DMS.
Insight into the Kinetics of Plasticity Using High-energy X-ray Diffraction: Armand Beaudoin1; Darren Pagan1; Kamalika Chatterjee1; Paul Shade2; Matthew Miller1; Sol Gruner1; Hugh Philipp1; Mark Tate1; 1Cornell University; 2Air Force Research Laboratory
Constitutive models for crystal plasticity are developed by relating a model idealization to (typically) scalar data from mechanical testing. High-Energy Diffraction Microscopy (HEDM), a technique using synchrotron radiation for study of polycrystalline materials, provides tensorial information that may be applied directly in validation of models for polycrystal plasticity. Advances in detector technology provide for extending the application of HEDM to details of the kinetics of plasticity. This is of particular consequence when multiple mechanisms of deformation are active – something quite difficult to sort out through traditional mechanical testing. In this work, we utilize a Mixed-Mode Pixel Array Detector with a CdTe sensor layer to explore transient plasticity in several different metals and alloys. Examples relating to the kinetics and intermittency of slip will be presented. Techniques of unsupervised learning will be applied in the analysis of diffraction data.
3D Analysis of the In-grain Orientation Spreads in Deformed Aluminium by 3DXRD-based Measurements and Finite Element Simulations: Romain Quey1; Loďc Renversade1; 1Mines Saint-Etienne
The development of the orientation distributions of 500 grains of an aluminium polycrystal deformed in tension were analysed. The undeformed microstructure was first characterized using diffraction contrast tomography (DCT). The grain lattice rotations were then followed by 3D X-ray diffraction microscopy (3DXRD) up to a strain of 4.5%. A new method was developed to extract the in-grain orientation distributions from the diffraction peaks, in which the parameters of a model orientation distribution are determined using forward simulation of diffraction and optimization. The properties of the orientation distributions were then analysed in terms of angular extent and anisotropy. It is shown that the 1st principal axes preferentially align with the tensile direction at strain lower than 2% and then migrate to a direction normal to the tensile direction. The results were compared to a crystal plasticity finite element simulation, and an agreement was concluded at largest strains.
Single Grain High Resolution Reciprocal Space Mapping: Ulrich Lienert1; Christian Wejdemann2; Wolfgang Pantleon3; 1Deutsches Elektronen-Synchrotron; 2Roskilde Katedralskole; 3Technical University of Denmark
In-situ structural characterization on the subgrain length scale within polycrystalline bulk materials has been demonstrated exploiting the high brightness of 3rd generation high-energy synchrotron facilities. At PETRA III the Swedish materials science beamline has been constructed and is expected to see first light in 2018. The capabilities regarding to 3D characterization will be described with particular emphasize on high resolution reciprocal space mapping (HRRSM). Dramatic further improvements will result from ongoing storage ring upgrades and efficient (CdTe) pixel detectors.The potential of HRRSM will be illustrated by a case study investigating strain path changes in copper. A statistically significant number of subgrains was identified. The existence of a microplastic regime was revealed during which only the subgrains deform plastically and no yielding of the dislocation walls occurs. Second, after reloading above 0.3% strain, the elastic stresses of individual subgrains are about the same as in uni-directionally deformed reference specimens.
Strain Field Around a Tin Whisker Studied Using Differential Aperture X-ray Microscopy (DAXM): Johan Hektor1; Jean-Baptiste Marijon2; Matti Ristinmaa1; Stephen Hall1; Hĺkan Hallberg1; Srinivasan Iyengar1; Jean-Sébastien Micha3; Odile Robach3; Fanny Grennerat4; Olivier Castelnau2; 1Lund University; 2Laboratory PiMM, Paris; 3BM32, ESRF; 4LGT Argouges
Tin (Sn) whiskers are microscopic, hair-like, grains that grow spontaneously out of surfaces coated with tin. Short circuits due to whisker growth have caused failure of many electronic components such as satellites, pacemakers and cell phones. It is generally accepted that whisker growth is a stress relaxation phenomena driven by strain gradients in the tin coating. However, experimental studies of the strain field around tin whiskers is largely missing. We have used Differential Aperture X-ray Microscopy (DAXM) to reconstruct the microstructure and strain field around a growing tin whisker in 3D. It was found that the deviatoric strain is high deep in the coating, where stress is generated due to formation of intermetallic compounds, and lower close to the whisker. Furthermore, there is a gradient in volumetric strain away from the whisker. This strain gradient is consistent with the expected driving mechanism for whisker growth.