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All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Manufacturing porous U-10Zr metallic fuels with controllable microstructure by volume control spark plasma sintering

In this paper, the volume control spark plasma sintering tool has been designed and applied to sinter porous U-10Zr metallic fuels, by which the sintered sample volume can be precisely controlled. Ethanol and NH 4 HCO 3 are used to control the powder compact or as pore formers to control the pore size and pore structure. Without pore formers, the fuel pellet displays an inhomogeneous microstructure consisting of highly porous and highly densified areas. Uneven powder stacking in the green body results in a non-uniform microstructure, and in the closed-packed area, Joule heating accelerates the neck formation and densification. The addition of ethanol reduces the friction between the powders, resulting in isolated pores formed by the stacking of powders during the sintering. By adding NH 4 HCO 3 , the pore size, and structure can be well controlled, and an interconnected pore structure can be obtained upon the decomposition of the NH 4 HCO 3 . Further, a uniform microstructure and pore distributions can be achieved through the U-10Zr fuel pellets by controlling current flow during the volume control SPS sintering. The microstructure and phase characterization of the sintered porous U-10Zr pellets show major phases of α-U and α-Zr for the sample with short dwelling. For the sample with long dwelling (30 min), the ω UZr 2 in the Zr-enriched area has been observed. The strategy of volume control SPS sintering with the assistance of pore formers could be used to fabricate porous U-10Zr metallic fuels to mimic the microstructure evolution of irradiated metallic fuels (including porosity) and could enable a possible solution for the design of new sodium-free metallic fuels for high burnup.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Transformation of a ceramic precursor to a biomedical (metallic) alloy: Part I – sinterability of Ta 2 O 5 and TiO 2 mixed oxides

Mixed Ta 2 O 5 – TiO 2 binary system was studied by a combination of differential thermal analysis (DTA), scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD) and in situ high temperature X-ray diffraction (HT-XRD) techniques. Different compositions of the mixed oxide powders were fabricated by ball–milling the powdered compositions, pelletizing the homogenized composite powders, and heating the green pellets in air at different temperatures for fixed time intervals. The sintered pellets were evaluated and characterized with respect to porosity, morphology, and phase distribution. DTA runs of the un-sintered powders indicated the onset temperatures for both exothermic and endothermic changes in the binary system. Significant amount of sintering was observed to take place at temperatures higher than 900 °C. Both room and high temperature X-ray diffraction patterns exhibited consistency in phase formation. A ternary compound (TaTiO 4 ) and a ternary solid solution (Ti 0.33 Ta 0.67 O 2 ) were observed to form in both room and high temperatures in addition to the respective binary phases (Ta 2 O 5 and TiO 2 ). A sintering temperature in the range 900–1000 °C was observed to be adequate to achieve the requisite mechanical strength and optimum internal porosity (40–48%) for subsequent electrochemical polarization experiments.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Shock initiation of low density polymer bonded explosive LX-14: A study of two morphologies

A series of six shock initiation experiments have been carried out on low density LX-14 powder in order to simulate a shock insult on the heavily damage polymer bonded explosive, LX-14. Two distinct morphologies were studied (tap density molding powder and machined swarf), both at the same density of 0.942 g/cm 3 , or 50.1% theoretical maximum density. The purpose of these experiments was to provide data to help make an assessment of the effects that damage has on the material sensitivity to a planar shock. This was achieved primarily by providing shock sensitivity data in the form of a Pop plot, and also reactants equation of state data, which aids in the determination of input conditions for both the experiments performed in this work and also future experiments of this material type. The experiments were of a cut-back format, consisting of four sample heights on each shot and diagnosed with optical velocimetry. The experiments were carried out at the Technical Area 40 Chamber 9 gas gun facility at the Los Alamos National Laboratory, where the LX-14 targets were subjected to Al 6061 and Oxygen Free High Conductivity copper impactors launched to velocities up to 2.14 km/s. Time corrected reactive growth wave profiles are presented in this paper along with the derivation of the following Hugoniot parameters for this explosive, where the molding powder and machine swarf are represented by the following linear equations, respectively, U s = 1.64 (±0.64)u p + 2.25 (±0.49) and U s = 0.87 (±.0.60)u p + 4.08 (±0.49). The results show that the steady increase in shock sensitivity with increasing void fraction reaches an inflection point beyond which the shock sensitivity begins to decease. This inflection point lies between 65% and 50% of the theoretical maximum density of the LX-14. In both cases, the damaged LX-14 was not as sensitive as expected, with a relative shock sensitivity of the molding powder being less than the pressed LX-14, and the machined swarf having a shock sensitivity that is comparable to pressed LX-14.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Alignment of magnetic particles in anisotropic Nd–Fe–B bonded magnets

High-performance anisotropic bonded magnets need a high volumetric filling fraction of magnetic powder in a polymer binder and good alignment while possessing adequate mechanical properties. The correlation between the degree of alignment (DOA) and the volumetric filling fraction of magnetic powder, the type of binder and the processing parameters have been studied using Nd–Fe–B anisotropic bonded magnets. Here, thermomagnetic analysis and differential scanning calorimetry results show that the magnetic powder can be well aligned in a bonded magnet under an external magnetic field at a temperature higher than the binders' melting point by 20–60 K, depending on the type of magnetic powder and binder. The DOA results mainly from the interplay between the Zeeman energy (E app ) and the inter-particle static energy (E stat ) in bonded magnets at the chosen alignment temperature and the magnetic fields. A good alignment can be achieved by an alignment magnetic field which is about twice its coercivity in an anisotropic Nd–Fe–B bonded magnet, which is confirmed by our experimental and modeling results.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Magnetic properties of the Ising-like rare earth pyrosilicate: D-Er 2 Si 2 O 7

Ising-like spin-1/2 magnetic materials are of interest for their ready connection to theory, particularly in the context of quantum critical behavior. In this work we report detailed studies of the magnetic properties of a member of the rare earth pyrosilicate family, D-Er 2 Si 2 O 7 , which is known to display a highly anisotropic Ising-like g-tensor and effective spin-1/2 magnetic moments. We used powder neutron diffraction, powder inelastic neutron spectroscopy (INS), and single crystal AC susceptibility to characterize its magnetic properties. Neutron diffraction enabled us to determine the magnetic structure below the known transition temperature (T N = 1.9 K) in zero field, confirming that the magnetic state is a four-sublattice antiferromagnetic structure with two non-collinear Ising axes, as was previously hypothesized. Our powder INS data revealed a gapped excitation at zero field, consistent with anisotropic (possibly Ising) exchange. An applied field of 1 T produces a mode softening, which is consistent with a field-induced second order phase transition. To assess the relevance of D-Er 2 Si 2 O 7 to the transverse field Ising model, we performed AC susceptibility measurements on a single crystal with the magnetic field oriented in the direction transverse to the Ising axes. This revealed a transition at 2.65 T at 0.1 K, a field significantly higher than the mode-softening field observed by powder INS, showing that the field-induced phase transitions are highly field-direction dependent as expected. Furthermore, these measurements suggest that D-Er 2 Si 2 O 7 may be a candidate for further exploration related to the transverse field Ising model.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Suppression of edge localized modes with real-time boron injection using the tungsten divertor in EAST

We report an observation of robust suppression of edge-localized modes (ELMs) in the Experimental Advanced Superconducting Tokamak (EAST), enabled by continuous boron (B) powder injection. Edge harmonic oscillations appear during B powder injection, providing sufficient particle transport to maintain constant density and avoid impurity accumulation in ELM-stable plasmas. Here, quasi-steady ELM suppression discharges are demonstrated with modest energy confinement improvement and over a wide range of conditions: heating power and technique variation, electron density range over a factor ~3.5, deuterium or helium ion species, and with either direction of the toroidal magnetic field. ELM suppression is observed above a threshold edge B intensity and ceases within 0.5 s of termination of the B injection. In contrast to ELM suppression accompanied by recycling reduction during Li powder injection in NSTX and EAST (Maingi et al 2018 Nucl. Fusion 58 024003), reduced recycling due to hydrogenic species retention is unnecessary for the ELM suppression with B powder injection, paving the way for its consideration as an ELM control tool for future fusion devices.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Plasma modification through boron particulate injection in the full tungsten environment of WEST

Recent experiments have confirmed the compatibility of extended boron particulate injections with high performance plasma discharges in the full tungsten (W) environment of WEST. Utilizing an impurity powder dropper (IPD) equipped with boron (B) powders a series of extended experimental programs providing controlled injections have quantified plasma response to varying levels of injection rate and total injection quantity. Calibration of injection quantities confirmed through post-situ testing of the IPD and cross-correlated with both high-speed camera illumination and spectroscopic measurement have allowed for the first time a fine scale determination of the effects of powder introduction on plasma performance. Plasma enhancement, consistent with turbulence reduction through profile modification, has been observed with sustained increases in the stored energy (WMHD), by 18%, electron temperature (T e ) by 35%, and neutron rate (N n ) by up to 200%, all of which scale positively with increasing powder injection rates. These injections have also resulted in both prompt and extended reductions in native impurity content, decreases in post injection radiated power, and strong decreases in divertor deuterium signatures signifying a reduction in recycling suggesting enhanced boron layer formation which provides a reduction of source terms and leads to enhanced gettering of main ion and impurity sources.

Lunsford, R. [Princeton Plasma Physics Laboratory ↗
DOE OSTI2026

Enabling On-Demand Aerospace Component Manufacturing: Topology Optimization of GE Engine Bracket and Fabrication Using Metal FFF

Additive Manufacturing (AM) offers advantages over conventional manufacturing processes, particularly by reducing the number of parts produced through multistage combined technologies, but these often result in low manufacturing yields or require post-processing. AM facilitates the production of complex geometries with fine features, overhangs, and lattice structures. For instance, Laser Powder Bed Fusion (LPBF) technology enables the fabrication of intricate parts that can be easily post-processed by removing residual powder. Laser powder bed AM technologies are widely discussed in the literature due to their design freedom in creating complex geometries, with and without the need for support generation. However, rapid solidification due to a thermal gradient in the build direction, which leads to the formation of columnar grains and warpage, is one of the challenges. To address this challenge, we propose layer-by-layer metal FFF technology, followed by the debinding and sintering process, as an alternative to powder- and laser-based approaches. Furthermore, design for additive manufacturing (DfAM) principles are discussed to minimize the need for support generation and enable easy post-processing, thereby improving surface finish to meet high tolerances in fabricating components for aerospace and healthcare applications.

Singh, Abhishek [University of Michigan, Ann Arbor↗
DOE OSTI2025

Chemical speciation correlated with microstructural heterogeneity of interdicted uranium materials

Two uranium powders seized by law enforcement in Victoria, Australia, have been characterized by established nuclear forensic methods in a previously published study. Here, in this work, the results of further characterization by a scanning transmission x-ray microscope (STXM) operating in the soft x-ray regime are reported. STXM images are used to estimate the elemental distribution in micrometer-scale particles of each powder, and oxygen K-edge absorption spectra are used to determine the chemical state of uranium. The results of the current study are consistent with the previous analysis; the first powder is found to be a potassium-uranium hydrate, while the second powder is determined to be a mixture of uranium oxides primarily consisting of UO 3 .

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

Probing Anion Exchange Membrane Fuel Cell Cathodes by Varying Electrocatalysts and Electrode Processing

To date, several high-performing anion exchange membrane fuel cells (AEMFCs) have been demonstrated, but most these studies have focused on Pt containing cathodes with high loadings. Here, we explore and compare the performance and perform electrochemical diagnostics on three leading AEMFC cathode electrocatalysts: Pt/C, Ag/C, and Fe–N–C with electrodes that have been processed with either powder or dispersion-based ionomers using perfluorinated anion exchange polymers. Pt/C had the highest performance but also showed a strong dependence on ionomer type, with powder ionomer exhibiting much higher performance. These results were consistent with the observations for Ag/C but did not hold for the Fe–N–C catalyst where almost no change was observed between powder and dispersion-based ionomers. This is the first-time the impact of powder and dispersion ionomer with different classes of cathode electrocatalysts on the fuel cell performance have been compared, and the results have strong implications for the ability to achieve high performance at low loadings and for better understanding catalyst-ionomer interactions within AEMFCs.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2020

Novel Ionomers and electrode structures for improved PEMFC electrode performance at low PGM loadings (Final Report)

In this project, the objective is to develop new ORR electrocatalysts on optimized supports which can exceed all of the Department of Energy (DOE) 2020 targets listed in DE-FOA-0001412 directly relevant to the subtopic. This project’s approach is to develop novel, electrode-specific ionomers, and integrate them with state-of-the-art NSTF electrocatalyst powder to develop a cathode electrode achieving >= 044 A/mg PGM mass activity, <=30% mass activity loss during metal cycling, and <=0.125 g PGM /kW performance under DOE testing protocols. Ionomer O 2 permeability and proton conductivity will be increased by up to 1.5X over the baseline 3M800 perfluorosulfonate (PFSA) ionomer to enhance cathode electrode performance. Integration of cathode NSTF powder into an ionomer-containing electrode will increase the surface enhancement factor (SEF) to >=40 cm 2 PGM /cm 2 GEO allowing NSTF containing cathodes to exceed DOE MEA robustness targets. This report summarizes this project’s progress towards meeting the stated objectives and includes a summary of significant findings, conclusions, and developments over the entire project period from Oct. 1 st 2016 – Jan. 31 st 2020. This work has overcome key operation robustness issues with classic NSTF electrodes, identified pathways to improved dispersed and dispersed NSTF cathode performance, developed novel ionomers with high bulk conductivity and oxygen permeability, demonstrated exceptional support-independent electrode activity, and significantly increased metal and support stability through ionomer development. At this point, Tufts, MTU and all 5 FCPAD national labs have been involved, and contributed to, the improvements, learning and achievements of this work. Over the course of this project, more than 50 grams of dispersed NSTF powder in 15 different configurations have been generated, paving the way for scaleup within 3M. These whiskers have been processed in multiple ways, including acid leaching, powder-annealed, and sonicated by various means. For Task 2, 27 different types of ionomers were tested, 19 of which were made for the first time during the course of this project. 377 electrode inks with both NSTF and metal-on-carbon catalysts with I/C ratios from 0.2 to 1.2 were generated and mostly coated on a 3M pilot manufacturing line resulting in more than 700 different electrode types.

08 HYDROGEN↗
DOE OSTI2020

Pulsed Thermal Tomography Nondestructive Examination of Additively Manufactured Reactor Materials (Second Annual Progress Report)

Additive manufacturing (AM) is an emerging method for cost-efficient fabrication of nuclear reactor parts. AM of metallic structures for nuclear energy applications is currently based on laser powder bed fusion (LPBF) process, which can introduce internal material flaws, such as pores and anisotropy. Integrity of AM structures needs to be evaluated nondestructively because material flaws could lead to premature failures due to exposure to high temperature, radiation and corrosive environment in a nuclear reactor. Thermal tomography (TT) provides a capability for non-destructive evaluation of sub-surface defects in arbitrary size structures. Thermal tomography is a computational method for heat diffusion-based imaging of solids, which provides 3D visualization of data from flash thermography measurements. We investigate thermal tomography imaging and nondestructive evaluation of stainless steel and nickel super alloy metallic structures produced with laser powder bed fusion (LPBF) additive manufacturing (AM) process. Metallic structures produced with LPBF contain defects, and there are limited capabilities to evaluate these structures non-destructively. Thermal tomography reconstruction of 3D apparent spatial effusivity provides information about AM structure geometry and internal material flaws. We study performance of thermal tomography in imaging of metallic structures through COMSOL computer simulations of transient heat transfer, and through reconstruction of data obtained from experimental measurements. Reconstruction of internal defects is investigated using a stainless steel 316L specimen with flat bottom hole (FBH) indentations, and Inconel 718 plate produced with laser powder bed fusion (LPBF) method, which contains imprinted hemispherical shape low density regions containing non-sintered metallic powder. The FBH’s have the same sizes as the imprinted defects in the LPBF specimens, but offer better imaging contrast. Thermal tomography reconstructions provide visualizations of internal defects, and allow for estimation of their sizes and locations. Detection sensitivity of TT is limited by noises. We investigate separation of signal from noise in thermography images using several machine learning (ML) methods, including new spatio-temporal blind source separation (STBSS) and spatio-temporal sparse dictionary learning (STSDL) methods. Performance of the ML methods is benchmarked using thermography data obtained from imaging stainless steel 316L and Inconel 718 specimens produced LPBF method with imprinted calibrated porosity defects. The ML methods are ranked by F-score and execution runtime. Finally, we investigate TT of AM stainless steel 316L specimen with imprinted internal porosity defects using relatively low-cost, small form factor infrared (IR) camera based on uncooled micro bolometer detector. Sparse coding related K-means singular value decomposition (SVD) machine learning, image processing algorithms are developed to improve quality of TT images through removal of Additive white Gaussian noise without blurring the images. Following initial qualification of an AM component for deployment in a nuclear reactor, a compact TT can also be used for in-service nondestructive evaluation (NDE). With capability to perform in-service NDE of the AM component lifecycle, TT data can be used for development of a component digital twin.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2022

Printability and Mechanical Properties of Polyethylene and Polyethylene/Nylon Blend Parts Made by Selective Laser Sintering

Improving the printability of polyethylene powder in selective laser sintering is of keen interest for the additive manufacturing community. Work to increase the variety of available feedstocks still must be done, as Nylon powder still constitutes a huge majority of all feedstocks used for selective laser sintering. Polyethylene is particularly of interest because it is a cheap, commodity polymer. Although some commercially available polyethylene powders exist, choosing one of these means the user is restricted to the specific polymer properties that those powders possess. Developing a reproducible processing parameter regime for polyethylene that exhibits other useful properties, such as very high densities or molecular weights, requires a uniquely tailored set of processing parameters. Particular emphasis will be placed on processing parameters that result in improved mechanical properties, as well as the possibility of successfully making SLS parts from polyethylene blends, e.g. polyethylene/Nylon blends.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Status of Additive Manufacturing Capabilities for Processing Refractory Alloys Under the Mo-99 Program

The enriched 100 Mo target, denoted as aMo, that Northstar Medical Radioisotopes is developing to produce 99 Mo from an accelerator-based method is a disk-type geometry with a 0.5–0.715 mm thickness and a 29 mm outer diameter. A press and sinter method was adopted to fabricate these samples from aMo powder feedstock. Inherent porosity from the press and sinter method makes the disks more easily dissolvable during 99 Mo postprocessing. However, the disk-type geometry will be subject to thermal stresses due to temperature variations once the geometry is in line with the accelerated electron beam, causing warping and possible failure. Additive manufacturing (AM) processes such as laser powder bed fusion (LPBF) enable the manufacturing of custom, complex geometries that may otherwise be difficult to produce with more conventional methods (e.g., press and sinter approach). Therefore, the National Nuclear Security Administration’s Molybdenum-99 Program invested in developing an AM facility dedicated to processing and printing refractory powders. This report details the LPBF process, how irregular refractory powder can be prepared for LPBF, and the equipment that is available to support the program.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Development & Validation of Low-Cost, Highly-Durable, Spinel-Based Materials for SOFC Cathode-Side Contact (Final Report)

A cathode-side contact layer is required to provide and maintain stable electrical conduction paths between the interconnect and cathode in a solid oxide fuel cell (SOFC) stack assembly and thus minimize the ohmic resistance and stack power loss. Current cathode-interconnect contact materials are based on noble metals, electrically-conductive perovskites, their composite materials, etc. These materials are either too expensive or do not possess the overall balanced performance required for the cathode-side contact application. To achieve the DOE SOFC system cost and performance stability goals, a new generation of low-cost, high-performance contact materials needs to be developed. In this project, spinel-based materials thermally converted from the Fe-Ni and Co-Mn based alloy precursors were developed and validated for the cathode-side contact application. The precursor alloy compositions were optimized via a combination of composition screening in the (Ni,Fe) 3 O 4 and (Mn,Co) 3 O 4 spinel system, alloy design using physical metallurgy principles, and cost considerations. The alloy powders with the desired composition and particle size were manufactured via gas atomization. The optimal process parameters for thermal conversion of these alloy precursor layers to a spinel-based layer were identified, i.e., 900°C x 2h in air, which is close to the initial stack firing condition. The area-specific resistances (ASRs) of the interconnect/contact/cathode test assemblies with the developed contact layer were determined for various durations (up to 5000 h) under simulated cathodic operation conditions. Some of the alloy-derived spinel contacts exhibited the lowest ASR and ASR degradation rate. The in-stack performance of the most promising alloy-derived contact layer is currently being evaluated via stack testing. To reduce the stack cost, the Co-Mn based alloy powders were utilized as the precursor for synthesis of dense spinel-based interconnect coating. By optimizing both the initial powder size/distribution and the alloy powder composition, a dense (Mn,Co) 3 O 4 -based spinel coating was achieved. Furthermore, co-sintering of the coating/contact dual-layer structure under the initial stack firing condition was realized by utilizing the tailored Co-Mn alloy precursors. Cost analysis of the developed technology indicated a total stack cost reduction of around 10.6% with the implementation of co-sintering of the interconnect coating and the contact layer during initial stack firing. Since low-cost processes such as screen printing is utilized in the precursor application and no reduction heat treatment is needed for the coating formation, the developed technology can be readily implemented at the industrial partner’s manufacturing facilities with no additional capital investment needed.

08 HYDROGEN↗
DOE OSTI2024

Near-Net-Shape Hot Isostatic Press Manufacturing Modality for sCO2 CSP Capital Cost Reduction

Through this DOE funded 3.5-year research project, feasibility of fabricating supercritical carbon dioxide (sCO2) turbine components by powder metallurgy (PM) based near-net-shape (NNS) hot isostatic pressing (HIP) was demonstrated in a turbine nozzle ring, a turbine casing with Haynes 282 powder, and a bimetallic pipe with Haynes 282 and SS415 powder. As-HIP microstructure of various powders and HIP processing conditions was studied to downselect a condition for the prototype components. Tensile strength and low cycle fatigue (LCF) capability of PM HIP 282 was found to be superior to cast 282, despite a debit in creep stress capability that could be mitigated by component design modification. Near-Net-shape with minimal post machining was achieved by modeling the non-uniform shrinkage during HIP cycle and designing the HIP tooling to meet dimensional targets. The prototypes of turbine nozzle ring and bimetallic pipe were successful in achieving overall dimension, microstructure, and properties, despite dimensional tolerance affected by chemical milling rate. The prototype of a 1700lbs turbine casing was partially successful in achieving dimension, microstructure in as-HIP state, and providing consistent mechanical properties, however, cracking issue during post heat treatment required further investigation. The estimated manufacturing cost using NNS HIP was a ~50% reduction compared to forging with extensive machining, which translated into ~$100/kWe CAPEX cost reduction for concentrated solar power (CSP) power block.

14 SOLAR ENERGY↗
DOE OSTI2025

Jump-Start U.S. Manufacturing of High-Performance Permanent Magnets

Gas atomized feedstock powders for Nd-Fe-B based magnets are more robust and cost effective than the strip-cast sheet currently used as feedstock for milling by the magnet industry. However, gas atomized powder’s crystallinity and grain boundary phases are less ideal than the strip cast flake. We proposed to optimize the atomization process as well as the powder chemistry to address this issue and to eliminate heavy rare earth elements from these magnet alloys. Our goal is to help GKN-Hoeganaes, a US metal powder company, who used to make Nd-Fe-B magnets, to bring back US manufacturing of these high energy density permanent magnets.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Microstructure Optimization and Novel Processing Development of ODS Steels for Fusion Environments (Final ARPA-E Report)

This project aimed to develop scalable, cost-effective fabrication of high-performance, oxide- dispersion-strengthened (ODS) steel using advanced manufacturing methods (AMMs) for fusion blanket-breeding applications. Gas atomization reaction synthesis (GARS) enables the synthesis of precursor ODS steel powders without prolonged mechanical alloying. This process creates a chromium (Cr)-enriched surface oxide with yttrium/titanium (Y/Ti)-enriched intermetallics in powder interiors. GARS powders were consolidated to >99% of the theoretical density using a first-of-a-kind shear assisted processing and extrusion (ShAPE) and laser-based powder bed fusion (L-PBF) AM processes. These processes led to ODS steels containing a high-density of nano-oxide dispersoids that enhance high-temperature mechanical properties. Such scalable, cost-effective fabrication of ODS steels can enable efficient power conversion cycles (=40%) at operating temperatures beyond 900 K in future fusion power plants.

36 MATERIALS SCIENCE↗