4th International Congress on 3D Materials Science (3DMS) 2018: Phase Transformations, Particle Coarsening, Grain Growth, and Recrystallization II
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

Tuesday 9:10 AM
June 12, 2018
Room: Store Scene
Location: Kulturværftet (Culture Yard) Conference Center

Session Chair: Michael Groeber, Air Force Research Laboratory

9:10 AM  Invited
Toward High-throughput 3D X-ray Characterization: Branden Kappes1; Henry Geerlings1; Nathan Johnson1; Dana Drake1; Thomas Gallmeyer1; Aaron Stebner1; 1Colorado School of Mines
    High flux X-ray sources are making 3D characterization more accessible. While they enable characterization of microstructural, morphological and dynamical processes, these techniques produce large data sets; and large data sets impose both practical and analytical challenges. Working with information about many hundreds to thousands of grains fosters the need to develop techniques that can differentiate statistically averaged behavior from the effects of even isolated defects. For example, void formation at hard-soft grain boundaries, which would be hidden in texture analysis, is critical for the mechanical performance of additively manufactured titanium. In additive manufacturing, each machine-material combination requires new process conditions, so non-destructive testing is critical to correlate process parameters, microstructure and mechanical performance. This presentation will focus on the microstructure and morphology of additively manufactured Inconel 718 and Ti-6Al-4V and the data management, analysis and informatics challenges and solutions developed to identify trends across hundreds of X-ray data sets.

9:40 AM  
In-situ 3DXRD Characterization of the Martensite Band Front in NiTi SMA Loaded in Tension: Pavel Sedmak1; Petr Sittner2; Jon Wright1; 1ESRF; 2Institute of Physics, ASCR
    It has been known for a long time that the martensitic transformation in NiTi-based SMAs deformed in tension occurs by propagation of macroscopic martensite band fronts leading to plateau-type stress-strain curve. The mechanism, shape and the strain-stress state at the front were, however, unknown. We performed a dedicated 3DXRD experiment at the ID11 beamline to study the burried interface. Strain and stress tensors within ~15000 austenitic grains were determined. It was found that the interface has a conical shape and the strain-stress distribution at the interface is very inhomogeneous. A mesoscale mechanism of the localized deformation was revealed and described by thermomechanical FE model. Strains and stresses within the martensitic part of the wire were measured by x-ray diffraction tomography technique at the new ID11 nanostage and are confronted with the thermomechanical model.

10:00 AM Break

10:30 AM  
Processing-microstructure Relationships in Isolated Melt Pools of Electron Beam Melted Inconel 718: Andrew Polonsky1; Narendran Raghavan2; McLean Echlin1; Michael Kirka2; Ryan Dehoff2; Tresa Pollock1; 1University of California, Santa Barbara; 2Oak Ridge National Laboratory
    Recent advances in additive manufacturing (AM) techniques offer a vast design space to create optimized structures for a variety of applications, including the aerospace and medical industries. The interplay between processing conditions and ultimate performance of additive parts remains an area of intense study. In order to achieve improved functionality of components through novel design, a thorough understanding of microstructural development and solidification processes arising at the scale of the melt pool size is required. Structural and crystallographic information of isolated melt pools on the order of a cubic millimeter was collected in three dimensions using the TriBeam tomography system. By varying build parameters, morphologically distinct microstructures were created to determine the effects of preexisting microstructures on subsequent solidification events. A comparison between experimentally observed microstructures and theoretical predictions will also be presented.

10:50 AM  
In Situ Hard X-ray Transmission Microscopy – Towards Space and Time Resolved Studies of Processes at the Nanoscale in Materials: Ragnvald Mathiesen1; Ken Falch1; Carsten Detlefs2; Marco Di Michiel2; Irina Snigireva2; Anatoly Snigirev3; 1Norwegian University of Science and Technology; 2ESRF; 3Fed. Balt. Univ. Kaliningrad
    Hard X-ray transmission microscopes are emerging at the new low-emittance synchrotron radiation sources. These instruments could pave the way for time-resolved in situ studies of microstructure formation and evolution at length scales down to 20-50 nm under realistic processing conditions. The new instruments could open for studies of several phenomena which in the past have been inaccessible via imaging-based approaches, such as self-organisation and pattern formation in nanomaterials, or heterogeneous nucleation processes. Access to experimental data at these time- and length scales would be of unprecedented value in the efforts to establish links between atomistic scale and continuum based computational models. The presentation will demonstrate various bright-field modalities of the instrument illustrated with a selection of possible case studies in material science.

11:10 AM  
Reconstruction of Three-dimensional Ferrite–Austenite Microstructure and Boundary Migration Analysis in an Early Stage of Ferrite to Austenite Phase Transformation in Fe-Mn-low C Alloy: Kengo Hata1; Kaori Kawano1; Masaaki Sugiyama2; Tomoyuki Kakeshita2; 1Nippon Steel & Sumitomo Metal corporation; 2Osaka University
    The crystallographic orientation relationship between ferrite and austenite in an early stage of the phase transformation upon heating has been investigated by three-dimensional EBSD analysis with FIB serial sectioning technique in Fe-Mn-low C steels. The three-dimensional ferrite–austenite microstructure was reconstructed from a microstructure quenched from the early stage of the phase transformation by determining the prior austenite orientation of the quenched martensite using a variant analysis method based on the K–S relationship. It was made clear that most of the austenite grains are transformed at grain corners in ferrite matrix. The crystallographic analysis has also revealed that the transformed austenite grain holds the K–S relationship or those close to it with two or three adjacent ferrite grains. Under in situ heating EBSD analysis on grain growth of the austenite at 790°C, the migration of the interfaces holding the K-S relationship is restricted.

11:30 AM  
Characterising Microstructural Evolutions in Ice Cream Using Synchrotron X-ray Tomography: Jingyi Mo1; Enyu Guo1; Gerard Van Dalen2; Peter Schuetz2; Peter Rockett1; Peter Lee1; 1University of Manchester - The Manchester X-Ray Imaging Facility; 2Unilever R&D
    Ice cream is a complex multi-phase colloidal system and its microstructure plays a critical role in determining consumers’ taste experience. Prior studies on ice cream, using 2D cryo-SEM or ex situ tomography, provides limited insights into the dynamic processes and mechanisms. Here, we performed in situ in-line phase contrast synchrotron tomographic imaging on ice cream samples. A bespoke cold-stage capable of precise thermal control was used to cycle samples from 250 K to 267 K at two cooling rates of 0.05 k/min and 5 k/min while the samples being continuously tomographically imaged. The morphology of ice crystals during these dynamic cycles was quantified. Our results demonstrate the effect of temperature and time on the coarsening kinetics of both ice crystals and bubbles in ice cream. The microstructural evolution of this multi-phase material will also provide insight into other research domains e.g. freeze casting (ice templating) of novel bio-inspired scaffolding materials.

11:50 AM  
New Possibilities Using Full Field High-tesolution 3D Synchrotron X-rays Methods for In-situ Recrystallization Studies: Yubin Zhang1; Dorte Juul Jensen1; 1Technical University of Denmark
    After 20-years development, the current generation synchrotron techniques, such as 3D X-ray Laue microdiffraction using differential aperture and diffraction contrast tomography, are powerful techniques for measurement of the crystallographic orientations, morphologies and local lattice strains of grains within bulk samples in full 3D. However, it is still challenging to study recrystallization of deformed metals with these techniques. In this presentation, several well-designed experiments performed using these techniques to study the recrystallization, including nucleation at hardness indents, grain boundary migration, and growth of several nuclei into a well-characterized deformation matrix will be presented. It is shown that with high-resolution (~1µm) mapping of both the deformation matrix and the recrystallized grains, the local heterogeneous nucleation and growth of recrystallized grains can be correlated to the local deformation microstructure. Key results are presented and it is discussed how the new results may be incorporated in next generation recrystallization models.