Advanced Characterization Techniques for Quantifying and Modeling Deformation: Poster Session
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division, TMS: Shaping and Forming Committee, TMS: Materials Characterization Committee
Program Organizers: Rodney McCabe, Los Alamos National Laboratory; Thomas Bieler, Michigan State University; Marko Knezevic, University of New Hampshire; Irene Beyerlein, University of California, Santa Barbara; Wolfgang Pantleon, Technical University of Denmark; C. Tasan, Massachusetts Institute of Technology; Arul Kumar Mariyappan, Los Alamos National Laboratory
Tuesday 5:30 PM
February 25, 2020
Room: Sails Pavilion
Location: San Diego Convention Ctr
K-1 (Digital): Computational Polarized Light Microscopy for Large Area Orientation Determination of Uniaxial Materials: Ke-Wei Jin1; Marc De Graef1; 1Carnegie Mellon University
Uniaxial materials such as alpha-titanium exhibit anisotropic optical properties. When illuminated using polarized light, grains of different crystallographic orientation reflect light differently, resulting in different intensities of recorded light. This behavior can be used to determine the c-axis orientation of titanium grains. Compared to other techniques for orientation determination such as EBSD, computational polarized light optical microscopy (CPLM) is low cost and has the ability to accommodate large samples. When used in conjunction with a forward model (FM), the speed of CPLM can be further increased. We will present the use of CPLM to perform orientation determination for large area sample cross-sections. Grain orientations determined using CPLM will be compared to orientations determined from EBSD. Finally, texture analysis will be used to analyze the large sample area.
K-2: Propagating Uncertainty through ICME Modules and Machine Learning towards Quicker and Accurate Distortion and Residual Stress Predictions: Brijesh Kumar1; Piyush Ranade1; Alonso Peralta1; Mustafa Megahed2; 1Honeywell Aerospace; 2Esi Group
Distortion and residual stress models provide useful information to designers and process engineers to assess manufacturability, geometric compensation and required post treatment. The model inputs coming from micromodels or via experiments vary leading to an uncertainty in distortion predictions. This study demonstrates how uncertainties are propagated from lower scale models to part scale models to assess the final uncertainty in residual stress and strain predictions. The data generated is also processed through machine learning algorithms investigating the potential of using reduced order models for multi-objective process optimization simulations. Experimental results are used to assess the reliability of the procedure and judge improvement needed to the methodology.
K-3: 3D Characterization of Nano-scale Precipitates in Shape-memory Alloys: Dexin Zhao1; Tejas Umale1; Jobin Joy1; Ibrahim Karaman1; Dimitris Lagoudas1; Kelvin Xie1; 1Texas A&M University
Shape-memory alloys (SMAs) have wide aerospace and biomedical applications due to the capability to recover from large deformations via solid-to-solid transformations from martensitic to austenitic phases. Recently, Ni-Ti-Hf SMAs have attracted tremendous research interests because their phase transformation temperature is higher than that of traditional Ni-Ti counterparts. This expands their applications in high-temperature environments. Our previous research has indicated that the presence of nano-scale precipitates could further improve the cyclic transformation response in the Ni-Ti-Hf system. However, there lacks a detailed understanding of these precipitates, including chemistry, size, distribution and volume fraction as a function of aging time and temperature. In this work, we use STEM tomography to construct 3D microstructures for these nano-scale precipitates. Using mean-field homogenization techniques, the effective mechanical behavior is predicted from the microstructure. We want to characterize and understand why nano-scale precipitates in SMAs could lead to even more consistent actuation responses in Ni-Ti-Hf SMAs.
Cancelled
K-4: Characterization of Defects in As-transformed and Hot-deformed τ-MnAl-C Alloys Using TEM: Panpan Zhao1; Kornelius Nielsch1; Thomas Woodcock2; 1IFW Dresden, Institute for Metallic Materials; 2IFW Dresden
The L10-ordered τ-MnAl is a highly promising rare-earth free permanent magnetic material; however, the low coercivity currently achieved is still the main obstacle for application. The reason for the low coercivity is that the microstructure of the material is characterized by a range of defects including dislocations, stacking faults, twin boundaries, grain boundaries and precipitates, all of which can potentially interact with magnetic domain walls. A thorough characterization of the nature of these defects is needed in order to fully understand their influence on the magnetic properties. In this study, defects have been characterized in as-transformed and hot deformed states by a variety of techniques in the transmission electron microscope (TEM) including two-beam and weak-beam dark-field analysis. This allowed the character of various types of defect to be established in detail and comparisons between the two states of the material to be made.
K-5: Characterization of Metal Powders for Spreadability and Flow Modeling: Taher Abu-Lebdeh1; Tobi Kalejaiye1; Sameer Hamoush1; Vincent Lamberti1; 1North Carolina A&T State University
In this study, powder characterization will be extended to evaluate the effects of Particle Size and Distribution, and Particle Morphology on powder spreading process. The study will also characterize powder flowability using measurements of shear strength, angle of repose, and Hausner ratio. Resulting from flowability investigation, we plan to relate flowability function to the angles of repose, and to recommend critical particle size for acceptable flow. Thus, we should be able to determine what powder characteristics make good, reliable powder spread, recommend critical particle size for acceptable flow, provide parameters used as good indicators of powder flowability. Also, we should be able to determine the variability of powders; characteristics of recycled powder; effect of fine particles in mixtures; and correlate powder properties with the mechanical properties of AM parts. The second part of the study involve quantitative studies and comprehensive theoretical insights into the particle property effects on powder flowability.
K-6: Characterizing the Influence of Microstructure on Twin Nucleation in Ferroelastic Ceramics: Charles Smith1; Jessica Krogstad1; 1University of Illinois Urbana-Champaign
Ferroelastic deformation is known to lead to increased toughness in many electroceramic and structural ceramic materials through the nucleation and motion of twins. However, the effect that local microstructure has on ferroelastic twin nucleation is not yet understood. Here, the influence of microstructural variables including grain size and crystal orientation on the probability of twin nucleation has been examined. Polycrystalline ceramics have been deformed using microindentation to evaluate the frequency and distribution of twin nucleation in differently sized grains. Additionally, in situ scanning and transmission electron microscopy with micropillar and nanopillar compression has been used to measure the stress associated with twin nucleation for single crystals of varying size and crystallographic orientation. High probability of twin nucleation was found to correlate to increased grain size, and twinning was suppressed in grains and single crystals as size decreased. These results may be used in the informed design of tough ceramic microstructures.
K-7: Comparative Analysis of Bulk and Local State of Thin Film Viscoelastic Material on a MEMS Device Using Dynamic Nanomechanical Characterization: Hasan Faisal1; Milosh Mededovic1; Patrick O'Hara1; 1Anton Paar USA
Instead of big advancement in the field of instrumented indentations, characterization of the soft viscoelastic material is still a challenging task. To this end, Anton Paar Ultra Nano Hardness Tester was employed to capturr the dynamic nanomechanical properties of thin viscoelastic silicone material. In this study, a unique surface referencing technique of the indentation testing was used to characterize the silicone material in bulk state and in local state on a MEMS device. To understand the local and bulk property variation, three different samples were tested with varying degree of curing. The indentation results show it can successfully capture the nanomechanical material property in both bulk and local encapsulated phase of sillicone. The dynamic response of three varying degrees of cured samples showed a dynamic storage modulus varies from 3.5 MPa to 4 MPa, whereas the loss modulus of the material was found around 0.55 MPa.
K-8: Determination of Strains in Clear Teeth Aligners for Orthodontics: Ning Ye1; Susan Mantell1; Alex Fok1; 1University of Minnesota
The aim of this study is to determine the strain distributions within these aligners during application, with the long-term goal being to understand the movement of teeth induced by these devices. The project contains two parts: simulation and experiment. Images of the aligner off and on the tooth model were processed by Digital Image Correlation (DIC) to obtain strain distributions for comparison with the finite-element (FE) prediction. The strain (eyy) distributions from the simulation and experiment are compared. From the occlusal (top) and buccal (side) views, strain concentrations could be seen in the intercuspal and interproximal regions of the aligner in both the simulation and experiment. Strain concentration was highest in the anterior region. The strain distributions from DIC validated the FE model of a clear teeth aligner for orthodontics. The forces induced on the teeth will be used to study tooth movement caused by the wearing of such devices.
K-9: Ex-situ and In-situ X-ray Studies of Crystal Structure and Microstructure Evolution in Metallic Alloys Under Extreme Environments: Tamas Varga1; Bharat Gwalani1; Arun Devaraj1; 1Pacific Northwest National Laboratory
Exposure to extreme environments (high pressure/shear, gas) alters both the surface and bulk structure of metallic alloys. To better understand such crystal and microstructure changes, we combined in-house x-ray capabilities with those at synchrotrons to investigate the evolution of crystal and microstructures of alloys under pressure/shear/gas flow. Laboratory XRD was used for ex situ characterization of alloys (Al-Si, Cu-Nb, Cu-Ni), and in situ studies of Zircalloy under H2/O2 exposure. In situ synchrotron XRD experiments were carried out on these alloys while compressed in a diamond anvil cell (shear added). X-ray tomography experiments were carried out for 3D structural information on the changes occurring on the microscale during processing. Our x-ray characterization was complemented with electron microscopy and atom probe tomography. The combination of all these techniques provided a more complete picture of phase and microstructure changes that follow the above processing of metallic alloys and influence their mechanical properties.
K-10: Imaging Microplasticity Events by Combining High Energy Diffractive Microscopy and Bragg Coherent Diffractive Imaging: Matthew Wilkin1; Anthony Rollett1; 1Carnegie Mellon University
Understanding plasticity events at the grain scale is key to the development of mesoscale models. High Energy Diffractive Microscopy (HEDM) has proven effective for determining grain-averaged elastic strain and grain orientation in a sample, but it provides no local strain information. Bragg Coherent Diffractive Imaging (BCDI) has been shown to provide 3D strain fields in individual grains but has largely been applied only to nano-particles, rather than polycrystals. We propose combining these two methods to image the interaction between several grains in a polycrystalline sample. HEDM gives us a 3D map of a microstructure in a sample, providing orientations for each grain. These orientations can be used to locate Bragg peaks for neighboring grains, allowing us to employ BCDI to investigate in 3D the interaction between two neighboring grains during heating or loading and the migration of defects within a particular grain.
Cancelled
K-11: Precipitation of Tetragonal τ-MnAl in a Twinned Rhombohedral Al8Mn5 Matrix: an EBSD Study: Thomas G. Woodcock1; Florian Bittner1; 1IFW Dresden
In the Mn-Al system, the rhombohedral phase Al8Mn5 (R3m, no. 160, Al8Cr5-type) exhibits complex microstructural features resembling warped chessboards, which result from stress minimisation during the phase transformation. Using EBSD it can be shown not only that these are based locally on assemblies of four different, twin-related structural units, but also that the units can be grouped into subgrains and further into grains. These reconstructed grains correspond to those of the parent bcc phase. On annealing such complex microstructures in which the Al8Mn5 phase is supersaturated with respect to Mn, the precipitation of the metastable phase τ-MnAl (P4/mmm, no. 123, AuCu-type) occurs. This phase is ferromagnetic and is of interest as a rare earth free permanent magnet. The apparent formation of τ-MnAl from an Al8Mn5 precursor is unusual and the orientation relationships to the matrix, precipitate morphology and defect structure will be examined in detail.
K-14: Slip and Twinning of Commercial Pure Titanium during In-situ Tensile Test: Joo-Hee Kang1; Hye In Jung2; Ji Hoon Kim2; Chang-Seok Oh1; 1Korea Institute of Materials Science; 2Pusan National University
Commercially pure (CP) titanium having hexagonal structure exhibits unusual anisotropy and asymmetry at room temperature. Activation of various slip and twinning is known to cause the complex deformation behavior of CP titanium. In this study, deformation behavior and microstructure variation in CP titanium were examined using in-situ tensile test and the crystal plasticity finite element analysis. The material parameters for the crystal plasticity model were calibrated using the macroscopic behavior under various loading conditions. The activated slip system was evaluated from observed slip traces. The deformation behavior in each grain with various orientations was investigated quantitatively. Prismatic slip system was dominant and tensile twinning was activated in CP titanium with lower oxygen content.
K-15: Thermal Corrections for Gleeble Right Circular Cylinder Compression Tests: Kevin Severs1; Ravi Shah1; Vikas Saraf1; 1Allegheny Technologies Incorporated (Ati)
Robust flow stress data is critical for accurate simulations of forgings in industrial applications. The Gleeble thermo-mechanical simulator is a commonly used piece of equipment for generating these data; however, the direct-resistance heating of the specimen introduces non-trivial thermal gradients within the sample that have a significant effect on the apparent flow stress. A technique will be described to quantitatively asses these gradients and their applicability in analyzing the data to develop such constitutive relationship for use in finite element models.
K-16: Thermo-mechanical Simulation of Steam Turbine Blade with Spark Plasma Sintering Developed NiCrCoTiAlW-Ta Superalloy Properties: Olugbenga Ogunbiyi1; 1Tshwane University of Technology
The efficiency of such supply is dependent on the operating parameters of the plants but at the expense of the useful life of the components. Turbine blade is one of the components that contribute immensely to such efficiency and it should be made of high-strength material with ability to withstand the harsh operation environment. The properties of spark plasma sintering (SPS) technique produced NiCrCoTiAlW-Ta superalloy was used in finite element analysis software, Abaqus CAE/2017 to simulate the thermo-mechanical behaviour of steam turbine blade. The maximum thermo-mechanical stress and strain was developed on the root of the turbine blade and the value of the maximum stress developed is far below the yield stress of the superalloy. Hence, SPSed NiCrCoTiAlW-Ta superalloy is suitable for turbine blade production as such blade will survive several thermo-mechanical stress and strain cycles prior to failure.
K-17: Transient Texture Evolution During Friction Stir Processing of a Mg Alloy Revealed by In-situ Neutron Diffraction: Yuan Li1; Ke An2; Zhili Feng2; Hahn Choo1; 1University of Tennessee; 2Oak Ridge National Laboratory
In order to gain fundamental understanding of dynamic recrystallization processes during friction stir processing (FSP) of Mg alloys, we investigated the transient texture evolution using in-situ, real-time neutron diffraction (ND). The texture evolution during FSP of AZ31B Mg alloy plates was studied at two extreme thermo-mechanical input conditions (in terms of Zener-Hollomon parameter, Z), namely low Z (1200 rpm, 0.1 mm/s) and high Z (300 rpm, 1.1 mm/s) conditions. The variations in the onset and extent of characteristic grain rotations during FSP as a function of location from the FSP tool pin and the Zener-Hollomon parameter will be presented. In addition, we will present the evolution of texture as a function of time during the processing using reconstructed pole figures measured in situ using ND. Finally, we will discuss the role of Z and material flow on the texture development mechanisms during FSP.
K-18: Understanding Deformation Mechanisms in a Low Ni/Co Alloy: Bharat Gwalani1; Govindarajan Muralidharan2; Dean Pierce2; Jonathan Poplawsky2; Donovan Leonard2; Libor Kovarik1; Arun Devaraj1; 1Pacific Northwest National Laboratory; 2Oak Ridge National Laboratory
Commercial Ni-base alloys IN751 is the most commonly used for higher performance exhaust valves, with a very good combination of strength and oxidation resistance. Oak Ridge National Laboratory has recently developed a new, alloy with lower Ni + Co alloy intended for operation up to 900oC and 950oC. This alloy is strengthened by the presence of ’ precipitates at these temperatures. However, there is interest in understanding the effectiveness of strengthening of these alloys at these temperatures. Hence we conducted detailed microstructural characterization before and after tensile and creep deformation to understand the deformation mechanisms. The deformation induced microstructural changes such as dislocation activity, precipitate morphology changes and deformation induced solute segregation etc. are investigated using both aberration corrected scanning transmission electron microscopy and atom probe tomography. Research sponsored by the U.S.DOE, Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies, under contract DE-AC05-00OR22725 with UT-Battelle, LLC.
K-19: Understanding the Deformation Mechanisms and Phase Transformations in High Alloy Metastable Austenitic Steels: Stefan Martin1; Christiane Ullrich1; Mykhaylo Motylenko1; David Rafaja1; 1TU Bergakademie Freiberg
High alloy austenitic CrMnNi steels undergo different deformation mechanisms as a function of chemical composition, strain rate, stress state and deformation temperature. These kind of iron-based alloys are advanced high strength steels, as new interfaces in the austenite grains are created by deformation twinning and martensitic transformations (ε- and α’-martensite) during plastic deformation, bringing about additional strengthening. Due to the chemically tunable low stacking fault energy of the fcc austenite, dislocation glide behavior is remarkably influenced, which provokes increased stacking fault formation. Stacking fault clusters are the nucleation site for the martensitic transformation and the deformation twinning. Using a combination of electron microscopy, electron backscattered diffraction and X-ray diffraction, the peculiarities of the deformation mechanisms and phase transformations and their interconnection is revealed. Through these insights, microstructure parameters can be identified entailing adequate modelling approaches of the mechanical behavior.