Characterization of Minerals, Metals and Materials: Advances in Characterization Methods II
Sponsored by: TMS Extraction and Processing Division, TMS: Materials Characterization Committee
Program Organizers: Jian Li, CanmetMATERIALS; Mingming Zhang, Baowu Ouyeel Co. Ltd; Bowen Li, Michigan Technological University; Sergio Monteiro, Instituto Militar de Engenharia; Shadia Ikhmayies, The University of Jordan; Yunus Kalay, Middle East Technical University; Jiann-Yang Hwang, Michigan Technological University; Juan Escobedo-Diaz, University of New South Wales; John Carpenter, Los Alamos National Laboratory; Andrew Brown, Devcom Arl Army Research Office

Monday 2:30 PM
February 24, 2020
Room: Theater A-5
Location: San Diego Convention Ctr

Session Chair: Jian Li, CanmetMATERIALS; Mingsheng He, Wuhan Iron & Steel Co

2:30 PM
Characterization of the World's Finest Gold at LANL: Sven Vogel¹; Raquel Alonso-Perez²; Michelle Espy¹; Cort Gautier¹; Adrian Losko¹; John Rakovan³; Frank Keutsch²; ¹Los Alamos National Laboratory; ²Harvard University; ³Miami University, Ohio
    A unique gold-silver alloy specimen, the so-called "Ram's Horn" with an unusual wire morphology, was characterized by multiple unique non-destructive methods at LANL: Neutron resonance absorption imaging provided elemental distribution, hard X-ray CT (using the spallation gamma flash by blocking the neutron beam on the same beamline as well as with a microtron source) to characterize density variations, and time-of-flight neutron diffraction to obtain spatially resolved microstructural characterization. The goal was to understand the origin of this unique specimen better, e.g. by comparing the microstructure with that of similar wire silver.

2:50 PM
Phase Transformation Characterization by Means of High Temperature Digital Image Correlation for Graded Thermo-mechanical Processing of Steel Sheet Parts: Alexander Reitz¹; Olexandr Grydin¹; Mirko Schaper¹; ¹Department of Materials Science, Paderborn University
     By locally adjusting the microstructure during the press-hardening process, the production of load-tailored safety relevant parts is possible. The thermo-mechanical treatment of 22MnB5 steel at different austenitization temperatures, cooling and forming conditions within a sheet leads to the development of mixed microstructures, which locally influence the material properties. A high number of experiments and specimens are necessary to determine the resulting phase composition in such graded parts.Within this study, a contactless characterization method to detect local phase transformations across an inhomogeneous treated flat steel specimen is developed. Digital image correlation and infrared thermography are used to identify transformation induced local straining during the inhomogeneous thermo-mechanical treatment. Flat steel specimens of 22MnB5 steel up to a thickness of 2 mm are tested. Coupling of temperature and strain fields enables the characterization of transformation kinetics for different austenitization temperatures, cooling rates and hot deformation strains with a reduced number of samples.

3:10 PM
Unconventional Sodium Chloride in Graphene Liquid Cell: Jaeyoung Hong¹; Jee-Hwan Bae¹; Hee-Young Park¹; Sehyun Lee¹; Juyoung Kim¹; Sung Jong Yoo¹; Dongwon Chun¹; ¹Korea Institute of Science and Technology
     Unconventional crystals can be produced at high pressure as it affects stability of crystals. Novel sodium chloride (NaCl) crystals with several compositions were reported recently.¹ We observed NaCl crystals formed inside graphene liquid cell (GLC) which was utilized to get high resolution image in liquid. It's well-known that an interplanar distance of (200) plane of conventional face-centered cubic (FCC) NaCl is 2.83Å. Interestingly, d-spacing of NaCl in GLC was less than 2.83Å, which is similar to that of Na₂Cl produced on graphene surface due to strong interaction between graphene and sodium cations in liquid.² In addition, diffraction pattern of the observed crystal is slightly different from FCC, indicating high pressure condition in GLC originated from van der waals force generated between graphene layers.³ References 1. Weiwei Zhang et al., Science 342 (2013) 2. Guosheng Shi et al., Nat. Chem. 10 (2018)3. G. Algara-Siller et al., Nature 519 (2015)

3:30 PM
A Fully Integrated In-Situ Solution for Materials Testing in Sem: Fang Zhou¹; ¹Carl Zeiss Microscopy GmbH
    In-situ material testing in SEM is an emerging trend among SEM applications, since it is a powerful method to link mechanical properties to the microstructures of materials. However, the integration of in-situ testing accessories into an SEM up to now is far from seamless and user friendly. The output is, on the other hand, very sobering in terms of scale of sample area interested, throughput and reproducibility of datasets. To address these shortcomings, a well-integrated solution for demanding in-situ testing, combining with the high-resolution surface sensitive imaging and EDS/EBSD analytical methods, is currently developed. The automated workflow can generate meaningful data with highest reproducibility and precision. The high-quality datasets acquired facilitate post processing and data analysis, for e.g. high-resolution strain mapping by means of digital imaging correlation (DIC). Further advancements such as automated feature tracking and autofocus help to realize true one-button-start workflows and experiments.

3:50 PM
Analysis and Detection of Road Surface Defects Using Multiple Sensing Methods: Jeongguk Kim¹; ¹Korea Railroad Research Institute
    In this study, we have investigated a technology to detect defects existing on the road surface efficiently. First, using the line laser technology, the profile of the road surface was inspected to examine the difference in the height of the road surface to understand the presence of the defect. The infrared thermography (IRT) technology was used to detect the temperature difference of the road surface, and estimated potential defects due to the temperature difference. In addition, the vision camera was used to visualize the defects on the surface of the road in conjunction with line laser and infrared thermographic images. Deep learning based fault detection technology was also applied for real-time analysis of defects while actual driving. Finally, a system has been developed to detect defects in real time using various advanced technologies. In this paper, the developed technologies and actual driving test results will be presented.

4:10 PM Break

4:25 PM
Autonomous Light Optical Microscopy for Quality Control Screening: Andrew Kitahara¹; Elizabeth Holm¹; ¹Carnegie Mellon University
    Quality control is a key initiative in manufacturing processes, and automating this process has desirable returns. We present a system that builds on automated stage control for conventional light optical microscopes along with recent successes in applied computer vision for materials characterization. Image acquisition utilizes reflected light optical microscopy with user-selected objectives. We approach the image analysis task with supervised fine-tuning of a convolutional neural network (CNN) to integrate expert knowledge of quality control engineers with an existing framework for image analysis. Image acquisition and analysis are run in parallel for autonomous defect detection. In this, the main goal is to identify and classify anomalous microstructural features for further expert inspection and action. The system we present addresses these key initiatives and offers a step towards autonomous data collection and curation for quality control applications.

4:45 PM
The Influence of Microstructure in Stress Relaxation Cracking: Dafni Daskalaki Mountanou¹; Tom McAuliffe¹; Chris Bilsland¹; Alex Foden¹; Thomas Britton¹; ¹Imperial College London
    Stress relaxation cracking (SRC) limits the life of industrial plant in oil & gas, nuclear power and aerospace applications. Typically, SRC is managed through material selection combined with qualification with thermomechanical testing. The nano- to micro-scale mechanisms, which are influenced by the microstructure, which control SRC are yet to be mechanistically understood. We propose using advanced characterisation techniques (SEM, EDS, HR-EBSD, and in situ mechanical testing) to correlate damage evolution with carbide types and grain boundary structure in nickel based alloys (Inconel 800 series). In these alloys, we use thermomechanical treatment to control grain size, carbide distribution and carbide types and understand their influence using digital image correlation, EBSD, and slip trace analysis and link this back to real-world applications.

5:05 PM
Austenite Stability Under Focused Ion Beam Milling: Jian Li¹; Pei Liu¹; ¹CanmetMATERIALS
     Artifacts from FIB milling can be of great concerns. Aside from commonly known defects (e.g., Ga ion implantation, re-deposition, specimen temperature increase, surface amorphization, etc.), FIB milling can even result in phase transformation in some metal alloys. One will have to be certain that the FIB prepared TEM specimen is a true representation of the bulk material. Limited study has shown normal incident Ga ion beam milling can transform FCC (austenite) to BCC structure in some stainless steels. This can be detrimental when residual austenite need to be analyzed. The susceptibility of austenite transformation to BCC is studied using EBSD on commercial stainless steels. When irradiated by normal incidence even with low dose, surface of SS304 and SS316 were completely transformed from austenite to BCC structure (ferrite or martensite). However, irradiation from high glancing angle does not result in any such transformation of relatively unstable austenite structure in SS304.

5:25 PM
Optical Characterization of Grain Orientation by Directional Reflectance Microscopy: Bernard Gaskey¹; Ludwig Hendl¹; Xiaogang Wang¹; Matteo Seita¹; ¹Nanyang Technological University
    Until now, the characterization of grain orientation or crystallographic texture in polycrystalline metals has been the exclusive domain of diffraction techniques. Directional reflectance microscopy (DRM) is an alternative that seeks to quantify crystallographic orientation optically by correlating optical reflectivity with surface structure. By imaging a sample repeatedly with monodirectional illumination from different angles, a directional reflectance profile can be computed, which contains detailed information about the local surface structure and underlying crystallography. We demonstrate DRM on a variety of metals which have been etched to reveal specific crystallographic facets. By indexing the reflections from these facets, DRM can map orientation in the same way as electron backscatter diffraction (EBSD). With the additional flexibility afforded by high throughput and simple equipment, DRM is a candidate to replace or compliment EBSD in a wide range of research and industrial applications.

5:45 PM
Accurate Determination of EBSD Pattern Centers with Applications in Resolving Pseudosymmetry: Edward Pang¹; Peter Larsen¹; Christopher Schuh¹; ¹Massachusetts Institute of Technology
    Accurate pattern center determination has long been a challenging problem in EBSD. With the rise of advanced EBSD techniques, accurate fitting of pattern centers is even more important as it limits the accuracy of these methods. However, quantitative aspects of this fitting landscape are still unknown. In this talk, we explore optimizing the pattern center and orientation by comparison to dynamically simulated reference patterns. This analysis reveals that the landscape is both “sloppy” and noisy, which limits the accuracy to which pattern centers can be determined. Based on this landscape, we have developed a fitting procedure that demonstrates good accuracy, precision, and robustness to noise and binning. We then apply this method to tetragonal zirconia and demonstrate its utility in resolving pseudosymmetry using dictionary indexing.