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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

High-Fidelity CFD Modeling of Cryogenic Hydrogen Isotope Extrusion for Fusion Reactor Pellet Fueling

This study investigates the extrusion processes of deuterium and protium using ANSYS-Polyflow. The geometries and computational fluid dynamics (CFD) settings closely replicate the experimental setups and data acquired from the extruder experiments at Oak Ridge National Laboratory (ORNL) for validation purposes. We explore the impacts of (1) slip versus non-slip boundary conditions and (2) the use of constant, temperature-, and shear rate–dependent viscosities, concluding that the implementation of non-slip wall boundary conditions combined with shear rate–dependent viscosity produced more accurate predictions. The simulations achieved excellent agreement with the experimental data, with relative differences of only 5% for deuterium, and 3% to 6% for protium. This is the first time that experimental extrusion data at ORNL have been accurately predicted through high-fidelity CFD modeling. In conclusion, the advancements offer valuable insights and a foundational modeling tool for optimizing pellet injectors for ITER and other future reactor-scale devices.

ANSYS-Polyflow↗
DOE OSTI2017

Investigation into Texture and Structure of MA2-1PCh Magnesium Alloy after Equal Channel Angular Extrusion and Annealing by Quantitative X-Ray Texture Analysis and Electron Backscatter Diffraction

This article discusses application of quantitative X-ray texture analysis (QTXA) based on measurement of direct pole figures and electron backscatter diffraction (EBSD) aimed at study of peculiarities of formation of texture and structure of MA2-1pch magnesium alloy after equal channel angular extrusion (ECAE) and subsequent annealing. Shear bands with the width of 60 μm oriented at 45°–50° to the extrusion direction are revealed, where an inclined scattered basis texture is detected, and outside of these bands, a prismatic texture. As a consequence, basic sliding is activated in the shear bands, which is confirmed by the distribution of Schmid factors. The influence of texture and orientation of shear bands on anisotropy of strength mechanical properties of alloy is discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Shear Assisted Processing and Extrusion of Magnesium Alloy Machining Chips

The Pacific Northwest National Laboratory (PNNL) utilized Shear Assisted Processing and Extrusion (ShAPE) to convert magnesium alloy machining chips directly into wrought material. PNNL fabricated 0.25” and 0.50” round rod from cold compacted briquettes pressed from dry-machined chips by Loukus Technologies. The alloy composition is proprietary and protected by a Materials Transfer Agreement (MTA) between PNNL and Loukus. Extrusions were fabricated using the ShAPE 2.0 machine, tooling, and process. PNNL is evaluating tensile properties per ASTM E8 and microstructure for grain size, texture, and porosity using Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction (EBSD). Tensile properties and microstructure results were not available at the time of writing this document. Extruded rods have also been sent to Loukus for evaluation.

36 MATERIALS SCIENCE↗
NASA NTRS2019

Extrusion of Complex Surface Meshes Utilizing Face Offsetting and Mean Curvature Smoothing

Grids for three-dimensional Computational Fluid Dynamics problems frequently require a prismatic layer of cells, typically extruded in the off-body direction from a two-dimensional surface mesh to properly resolve boundary layers. When the surface geometry is complex, the extrusion process can fail, resulting in the physical boundary layer being thicker than the prismatic layer, leading to under-resolved boundary layers. To address the shortcomings of existing grid generation tools, a new tool has been developed as part of the Mesh Tools suite, that is capable of extruding complex surface meshes. The new tool uses a face offsetting method to preserve surface curvature and a mean curvature smoothing algorithm to prevent the cells from self-intersecting in concave regions. Testing of the new tool found that not only were complex surface meshes able to be extruded to the desired thickness, but extrusion of simple surface meshes was also improved, due to the face offsetting method.

mesh extrusion↗
DOE OSTI2022

Anisotropic thermal behavior of extrusion-based large scale additively manufactured carbon-fiber reinforced thermoplastic structures

Large format additive manufacturing (AM) enables rapid manufacturing of large parts and structures with minimum waste in material and energy. Extrusion-based AM deposition processes provide parts with highly anisotropic thermal properties, which are not typically reflected in textbook values for these materials. In order to develop accurate models that describe the directionally dependent thermal behavior of these materials in processing and service, accurate measurements of specific heat capacity and thermal conductivity are required. Here, this work characterizes, documents, and analyzes the effect of the anisotropic nature of the extrusion-based deposition process on the specific heat capacity and thermal conductivity of the resulting AM products. All measurements were made over a temperature range of 20–180°C using the transient plane source technique, also referred to as the hot disk technique. Three of the most commonly used large format AM feedstock materials that utilize carbon fiber reinforcement were examined in this work: acrylonitrile butadiene styrene, polyphenylene sulfide and polyphenylsulfone. Finally, these findings can serve as a thermal design/process guideline for future large format AM applications.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Rheological behavior of neat and carbon fiber-reinforced poly(ether ketone ketone) for extrusion deposition additive manufacturing

To develop new materials for extrusion additive manufacturing (AM) systems, a fundamental understanding of rheological properties is essential to correlate the effect of processing on material structure and its properties. In this work, the rheological properties of five different grades of neat and carbon fiber (CF)-reinforced poly(ether ketone ketone) are reported. Rheological properties are essential to understand the effect of reinforcing fibers and AM process parameters such as time, temperature, environment, and shear rate on flow behavior during processing. Small-amplitude oscillatory shear tests and steady shear tests indicated neat grades to exhibit less increase in viscosity over time when processed in air than the CF-filled grades. The filled grades showed greater shear thinning and lower sensitivity to temperature. Altogether, this rheological analysis provides a broad framework for determining appropriate processing conditions for extrusion deposition AM of such high-temperature polymer systems.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Extrusion Parameters for Foaming of a β-Glucan Concentrate

Plastics is a group of materials commonly encountered on a daily basis by many people. They have enabled rapid, low-cost manufacturing of products with complicated geometries and have contributed to the weight reduction of heavy components, especially when produced into a foamed structure. Despite the many advantages of plastics, some drawbacks such as the often fossil-based raw-material and the extensive littering of the material in nature, where it is not degraded for a very long time, needs to be dealt with. One way to address at least one of the issues could be to use polymers from nature instead of fossil-based ones. Here, a β-glucan concentrate originating from barley was investigated. The concentrate was processed into a foam by hot-melt extrusion, and the processing window was established. The effect of different blowing agents was also investigated. Water or a combination of water and sodium bicarbonate were used as blowing agents, the latter apparently giving a more uniform pore structure. The porous structure of the foamed materials was characterized mainly by using a combination of confocal laser scanning microscope and image analysis. The density of the samples was estimated and found to be in a similar range as some polyurethane foams. A set of 3D parameters were also quantified on two selected samples using X-ray microtomography in combination with image analysis, where it was indicated that the porous structure had a pre-determined direction, which followed the direction of the extrusion process.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Friction Extrusion: Solid-State Metal Synthesis and Recycling in Sustainable Manufacturing

Friction extrusion (FE) is a novel solid-state process for synthesis and recycling of metals and alloys. The novelty of FE is that it utilizes the frictional heating and extensive plastic deformation intrinsic in the process to stir, mechanically alloy, consolidate, and convert powders, chips, and other recyclable feedstock metals into a usable product form of highly engineered materials. FE represents a potentially transformational sustainable manufacturing technology. Being a solid-state process, it eliminates the energy-intensive melting and solidification steps, which are necessary in the conventional metal recycle and synthesis processes. Therefore, FE is a highly energy-efficient, practically zero-emission, and economically competitive process. Here, in this work, the concept and configuration of FE are introduced, the energy-saving advantage of FE is analyzed, the feasibility of FE is demonstrated with synthesizing Al alloys, and the results of some metallographic and mechanical properties studies are presented. A prognosis of the friction extrusion technology is outlined.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Manufacturing ODS Steels from GARS Powders by Friction Consolidation and Extrusion

Previous research suggested that friction-based processing is a promising method for fabricating oxide dispersion-strengthened (ODS) steel. In this study, we combined friction consolidation and friction extrusion to successfully manufacture ODS steel rods using precursor powder made with gas atomization reaction synthesis. We examined the microstructure evolution from the initial powder to the final extruded rod, which revealed the dispersion process of Y. Additionally, by comparing the microstructures of three rods extruded at different temperatures, we showed that low-temperature friction extrusion effectively enhanced microstructure uniformity and prevented grain coarsening, leading to improved mechanical properties. Furthermore, our findings provide practical guidelines for adjusting processing parameters in the production of ODS steel using friction-based processing.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Review of Solid State Consolidation Processing Techniques of ODS Steels (Hot Extrusion, Hot Isostatic Pressing, Spark Plasma Sintering, and Stir Friction Consolidation): Resulting Microstructures and Mechanical Properties

This paper reviews the solid-state consolidation processing techniques for Oxide Dispersion Strengthened steels and compares them in terms of the resulting microstructure and reported mechanical properties. Synthesis techniques include hot extrusion, hot isostatic pressing, spark plasma sintering and friction consolidation. The effects of process parameters on the resulting microstructures and performance are discussed for each technique. Average oxide size, average grain size, and porosity are compared across techniques, as well as mechanical strength and ductility. Across consolidation techniques where temperature can be controlled, a low sintering temperature with a high sintering pressure is favorable for keeping oxide sizes, grain sizes, and porosity low. The use of yttrium and titanium for oxide formation has been evidenced to reduce oxide sizes, and tungsten additions have been shown to improve strength. Current literature suggests that the more mature hot extrusion technique produces stronger steel with consistently fine oxides, while other alternative solid-state consolidation, while promising, offer margin for improvement.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Meshfree simulation and experimental validation of extreme thermomechanical conditions in friction stir extrusion

Abstract Friction stir extrusion (FSE) is a novel solid-phase processing technique that consolidates and extrudes metal powders, flakes, chips, or billets into high-performance parts by plastic deformation, which has the potential to save substantial processing time and energy. Currently, most studies on FSE are experimental and only a few numerical models have been developed to explain and predict the complex physics of the process. In this work, a meshfree simulation framework based on smoothed particle hydrodynamics (SPH) was developed for FSE. Unlike traditional grid-based methods, SPH is a Lagrangian particle-based method that can handle severe material deformations, capture moving interfaces and surfaces, and monitor the field variable histories explicitly without complicated tracking schemes. These aspects of SPH make it attractive for the FSE process, where in situ evolution of field variables is difficult to observe experimentally. To this end, a 3-D, fully thermomechanically coupled SPH model was developed to simulate the FSE of aluminum wires. The developed model was thoroughly validated by comparing the numerically predicted material flow, strain, temperature history, and extrusion force with experimental results for a certain set of process parameters. The validated SPH model can serve as an effective tool to predict and better understand the extreme thermomechanical conditions during the FSE process.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2018

Influences of interstitial and extrusion temperature on grain boundary segregation, Y-Ti-O nanofeatures, and mechanical properties of ferritic steels

Doping with interstitials influences the grain boundary (GB) composition of metallic alloys, enabling changes in elemental GB enrichment, grain size, and mechanical properties or even promoting nanoparticle formation. Yet, little efforts on these doping effects have been made in oxide dispersion-strengthened (ODS) steels. In this paper, by combining advanced microscopy techniques, we studied the impact of interstitial concentration and extrusion temperature on the GB structure-dependent solute segregation, Y-Ti-O nanofeatures, and mechanical properties of ferritic Fe–14Cr (wt%) ODS steels fabricated by ball milling. We found that doping with high carbon and oxygen contents causes the GB to be decorated with the interstitials and promotes nanoparticle formation along the GBs, thereby retarding capillary-driven grain coarsening. This effect performs twofold, through grain size refinement and particle hardening. For samples with low interstitial contents, altering the extrusion temperature does not significantly change the material's mechanical properties and microstructure or the nonstoichiometric chemistry of nanoparticles, which are highly stable at high temperatures. Finally and further, for all the samples, Y–Al oxides in the initial precipitation stages rapidly become coarsened at high temperatures, as Al weakens the thermal stability of nanoparticles, thereby transforming them to core-shell structures with Y-Al-rich cores and Ti-O-rich shells in the later precipitation stages.

36 MATERIALS SCIENCE↗
DOE OSTI2026

A meshing framework for digital twins for extrusion based additive manufacturing

Additive manufacturing (AM) allows for manufacturing of complex three-dimensional geometries not typically realizable with standard manufacturing practices. The internal microstructure of AM components has a significant impact on mechanical, vibrational, and shock properties and permits richer design space when this is controllable. Due to complex interactions of internal geometry of an extrusion-based AM component, it is common practice to assume homogeneous behavior or to perform characterization testing on specific toolpath configurations. To avoid testing or material waste, it is necessary to develop a consistently accurate numerical simulation framework with relevant boundary value problems that can handle the complicated geometry of internal material microstructure present in AM components. Herein, a framework is proposed to directly create computational meshes suitable for finite element analysis (FEA) of the fine-scale features generated from extrusion-based AM tool paths to maintain a strong process–structure–property-performance linkage. This mesh can be manually or automatically analyzed using standard FEA simulations such as quasi-static preloading or modal analysis. The framework allows an in-silico assessment of a target AM geometry where fine-scale features greatly impact quantities of design interest such as in soft elastomeric lattices where toolpath infill can greatly influence the self-contact of a structure in compression, which we use as a motivating exemplar. This approach greatly reduces both time and resource waste present in traditional build and test design cycles for non-intuitive design spaces, and acts as a tool for use in the production of a key component of a digital twin, a mesh suitable for finite element analysis. In conclusion, it also further allows for the exploration of toolpath infill to optimize component properties beyond simple linear properties such as density and stiffness.

Additive manufacturing↗
DOE OSTI2018

Influence of mechanical alloying and extrusion conditions on the microstructure and tensile properties of Low-Cr ODS FeCrAl alloys

Low-chromium (<10%Cr) high strength oxide dispersion strengthened (ODS) FeCrAl alloys are considered promising candidates for accident tolerant fuel cladding in light water fission reactors. These alloys are designed to combine the beneficial high temperature mechanical properties of ODS materials with the exceptionally high temperature oxidation resistance of FeCrAl in comparison to conventional Zr-containing cladding materials, while also providing good mechanical and aqueous corrosion behavior under normal light water reactor operating conditions. The initial (1st generation) ODS FeCrAl alloys combined gas atomized FeCrAl powders with yttria and other oxides for alloying element additions using the mechanical alloying approach. These alloys exhibited low ductility but excellent high temperature tensile strength while maintaining good oxidation resistance at temperatures up to 1400 °C. In an attempt to improve alloy ductility for accident tolerant fuel cladding applications, new low-Cr ODS FeCrAl alloys with decreased oxygen content were developed with the Zr alloying solute already gas atomized into the powder prior to mechanical alloying. The resultant Fe-10Cr-6.1Al-0.3Zr+0.3Y 2 O 3 (106ZY) powders were ball milled for 10, 20, and 40hr followed by consolidation via hot extrusion at temperatures ranging from 900 to 1050 °C. Increasing the mechanical alloying time decreased the resultant grain size and improved high temperature tensile properties. Decreasing the extrusion temperature refined the grain size and subsequently strengthened the ODS FeCrAl 106ZY alloys while lowering the ductility. Scanning transmission electron microscopy (STEM) and energy dispersive spectroscopy (EDS) demonstrated the Zr solute addition effectively sequestered impurity C and N within the matrix. The root mean square (RMS) hardening superposition model for yield strength shows good agreement with experimental results. Errors between predicted and experimental values are discussed within the scope of processing parameters. As a result, these 2nd generation 106ZY alloys show a distinct increase in alloy ductility without sacrificing the high temperature tensile properties characteristic of legacy or 1st generation ODS FeCrAl alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Microstructure and mechanical properties of duplex stainless steel subjected to hydrostatic extrusion

The nanostructure and mechanical properties of ferritic-austenitic duplex stainless steel subjected to hydrostatic extrusion were examined. The refinement of the structure in the initial state and in the two deformation states (ε = 1.4 and ε = 3.8) was observed in an optical microscope (OM) and a transmission electron microscope (TEM). The results indicate that the structure evolved from microcrystalline with a grain size of about 4 μm to nanocrystalline with a grain size of about 150 nm in ferrite and 70 nm in austenite. The material was characterized mechanically by tensile tests performed in the two deformation states. The ultimate strength appeared to increase significantly compared to that in the initial deformation stages, which can be attributed to the grain refinement and plastic deformation. The heterogeneity observed in microregions results from the dual-phase structure of the steel. The results indicate that hydrostatic extrusion is a highly potential technology suitable for improving the properties of duplex steels. - Highlights: • Duplex stainless steel was hydro extruded to a total strain of 3.8 • After the last stage of deformation heterogeneous structure was obtained in the material • As a result of stresses non-diffusive transformation γ→α’ occurred in the material • Nanometric (sub)grains were obtained in the austenite regions.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Morphology-Controlled Discharge Profile and Reversible Cu Extrusion and Dissolution in Biomimetic CuS

Metal sulfides, such as CuS, SnS2, Co9S8, MoS2, are high capacity anode materials for Li-ion batteries. However, these materials go through a conversion reaction with Li+, which is accompanied by the phase transformation and inevitably results in a huge volume expansions, therefore causing performance degradation. Here, we report nanoscale engineering route to efficiently control the overall volume expansion for enhanced performance. We engineered CuS with nanoplate assembly on a nanostring, leading to a nanostructure of mimicking the crassula baby necklace (CBN) in the natural plant. Using in-situ transmission electron microscopy (in-situ TEM), we probed the lithiation kinetics and dynamic structural transformations. Due to the linkage of the central nanostring, the CuS CBN exhibited fast Li+ diffusion along the axial direction and high mechanical stability during lithiation. The volume expansion was minimal for the CuS CBN due to the pre-engineered gap between these plates. The CuS followed a two-step lithiation process with Cu2S and Li2S formation as the first step and Cu extrusion from Cu2S in the later stage. Interestingly, during the Cu2S to Cu conversion, there was a incubation period before the metallic Cu extrusion, which is featured by the formation of an amorphous structure due to the large lattice strain and distortion associated with the displacement of Cu by Li ions. In the final stage, the lithiated amorphous phase recrystallized to a composite of Cu nanocrystals dispersed in a polycrystalline Li2S matrix. Associate with the nanoscale size, the Cu nanocrystals can reversibly dissolve into the matrix upon delithiation. The present work demonstrates tailoring of desired functionality through nanoscale engineering of using bionic methods.

Han, Shaobo↗
DOE OSTI2025

Warpage-Resistant, Under-Extrusion-Free, High-Surface-Quality Additive Manufacturing Process for Polyethylene-Based Composite Radiation Shielding Material

Polyethylene (PE) is one of the best shielding materials for primary space radiation due to its high hydrogen content. For effective secondary neutron shielding, boron-rich fillers are incorporated to enhance performance. The semicrystalline nature and high thermal expansion coefficient of PE impede its adoption for in situ additive manufacture in space via the fused deposition modeling (FDM) 3D printing. Here, we developed an optimized PE blend to mitigate the effects of under-extrusion and warpage. Guided by studies on extrusion and warpage, we developed an optimal set of printing parameters for the proposed PE blend. The optimum PE blend─both in its pure form and when doped with fillers─has been tested on different FDM printers. The printed structures exhibit high and uniform density, smooth surfaces, no warpage, and competitive mechanical properties. The FDM-printed plates demonstrate efficient shielding from thermal neutrons, predicted via modeling and confirmed experimentally using extended Q-range small-angle neutron scattering.

additive manufacturing↗