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At least 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Concentrating Rare Earth Elements in Coal mine drainage Using Coal Combustion Products through Abandoned Mine Land Reclamation

Rare earth elements (REEs) (including scandium, yttrium and a group of 15 lanthanides) are often considered to be critical components in the productions of renewable energy hardware, electric vehicles, health care and military equipment, and consumer electronic products. The demand of REEs has been projected to be growing at an annual rate of 5-9% in the next 25 years. In 2011, the global demand of total rare earth oxides (REOs) was estimated to be approximately 105,000 tons, which is expected to grow to 210,000 tons by 2025. China overwhelmingly dominates the current worldwide rare earth productions but has strategically restricted its exports, causing significant instability for the global market. In response to the increasing demand for REEs and the supply dominance of China, identifying alternative sources of REEs has become a critical issue for the United States and other countries. Coal, coal ash, and coal mine drainage (CMD) are considered to be the alternative sources of REEs. In the U.S., high REE concentrations have been reported to be closely associated with coal deposits, including the Appalachian Basins. When surface and/or groundwater come in contact with geologic strata containing sulfide minerals exposed by coal mining, the accelerated oxidation of sulfide minerals in the presence of ferric iron and/or oxygen can produce sulfuric acid. The process promotes the weathering of REE-bearing rocks and minerals in the host geologic strata. Compared to average river water and seawater, the concentrations of REEs can be orders of magnitude higher in CMD. In this study, we demonstrated a trap-extract-precipitate (TEP) process that can effectively recover REEs from CMD. The three-stage TEP process uses alkaline industrial by-products to capture REEs from CMD and then applies an extraction/precipitation procedure to produce a feedstock that can be economically processed to produce marketable rare earth oxides. The alkaline industrial by-products tested in this study include the residual from a water softening process (DRWP sludge) and two types of stabilized flue gas desulfurization materials (sFGDs). sFGD material is a mixture of lime (CaO) and two coal combustion by-products, calcium sulfite FGD by-product and fly ash. The objectives of this study are to (1) validate the effectiveness and feasibility; (2) determine mechanisms controlling the rare earth recovery, (3) quantify the associated economic and environmental benefits, and (4) evaluate the full-scale application. To achieve these objectives, tasks to be carried out in this proposed project are organized into three phases. In the first phase, the research team collaborated with Ohio Department of Natural Resources, American Electric Power, The Wilds (a nonprofit wildlife conservation organization), and a private landowner to carry out field investigations aimed to screen and evaluate the seasonal changes of rare earths in the CMD discharges that have high recovery potentials. Next, the recovery of REEs from CMD was tested using a series of lab-scale column and batch tests under, respectively, percolation and completely mixed conditions. Results obtained from these lab-scale studies show that all three tested solids are very effective in retaining REEs. Over 98% of the CMD REEs that contacted the solids were captured before the solids exhausted their neutralization capacities. We also determined an extraction process using a non-acid, organic ligand extraction solution that can effectively remobilize the retained REEs from the spent solids (over 90%). The REE concentrate (>7.5 wt. % of total REEs) is then formed in an aeration process. The TEP process uses environmentally benign industrial by-products and a naturally-occurring organic ligand to mitigate CMD and recover REEs. Techno-economic analysis (TEA) and life-cycle assessment (LCA) was carried out in the third phase. The engineering-economic costs and net energy, net CO2 emissions, and water and other requirements were investigated to understand the economic and environmental implications of this process. This work uses mass and energy balances from laboratory-scale experiments to estimate the economic costs and environmental impacts. The results suggest that passive treatment systems that use DRWP sludge are preferred over those that use sFGD material, because of lower economic costs ($89,300/yr with a unit cost of $86/gT-REE vs. $89,800/yr, or $278/gT-REE) and improved environmental performance across all indicators from two different impact assessment methods. These differences are largely attributable to the larger capacity of DRWP sludge in the passive treatment application. We envision this TEP process can be integrated with abandoned mine land (AML) reclamation to create an approach that can add economic incentives for AML reclamation, remediate CMD discharge, and eliminate public safety hazards and threats to local environment and ecological systems posed by AMLs. It can restore lands and communities that are adversely impacted by legacy mining.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2016

Nanostructured silicon nitride from wheat and rice husks

Nanoparticles, submicron-diameter tubes, and rods of Si{sub 3}N{sub 4} were synthesized from the thermal treatment of wheat and rice husks at temperatures at and above 1300 °C in a nitrogen atmosphere. The whole pattern Rietveld analysis of the observed diffraction data from treatments at 1300 °C showed the formation of only hexagonal α-phase of Si{sub 3}N{sub 4} with an R-factor of 1%, whereas samples treated at 1400 °C and above showed both α- and β-phases with an R-factor of 2%. Transmission electron microscopy showed the presence of tubes, rods, and nanoparticles of Si{sub 3}N{sub 4}. In a two-step process, where pure SiC was produced first from rice or wheat husk in an argon atmosphere and subsequently treated in a nitrogen atmosphere at 1450 °C, a nanostructured composite material having α- and β-phases of Si{sub 3}N{sub 4} combined with cubic phase of SiC was formed. The thermodynamics of the formation of silicon nitride is discussed in terms of the solid state reaction between organic matter (silica content), which is inherently present in the wheat and rice husks, with the nitrogen from the furnace atmosphere. Nanostructures of silicon nitride formed by a single direct reaction or their composites with SiC formed in a two-step process of agricultural byproducts provide an uncomplicated sustainable synthesis route for silicon nitride used in mechanical, biotechnology, and electro-optic nanotechnology applications.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Exploring the Nucleon Structure via Deep Electroproduction Processes

Understanding the internal structure of the nucleon is a fundamental goal of modern physics, which aims at a comprehensive framework describing the internal dynamics of quarks and gluons. Among other structure functions, Generalized Parton Distributions (GPDs) offer a powerful framework for describing the nucleon dynamics by correlating the longitudinal momentum and the transverse position of its internal partons. Such a correlation provides a three-dimensional picture of the nucleon and enables access to fundamental properties, including the internal pressure distributions and the parton’s angular momentum contribution to the nucleon's total spin, thereby playing a central role in resolving the nucleon spin puzzle. At the Thomas Jefferson National Facility (JLab), polarized electron beam experiments allow for probing GPDs through the measurement of hard exclusive processes. Among the cleanest experimental channels, we find the electro-production of a real photon through the Deeply Virtual Compton Scattering (DVCS) mechanism. The first data-taking period of the CLAS12 program, taking place in 2018, allowed for unique DVCS Beam Spin Asymmetry (BSA) measurements in the phase space covered by a 10.6 GeV polarized electron beam impinging on an unpolarized liquid hydrogen target. Although detecting all final-state particles ensures exclusivity of the process, conservation laws indicate that it is not mandatory. I adopt an approach omitting the direct detection of the recoil proton, providing a simplified yet effective event selection strategy that boosts statistics and gives access to a larger phase space sensitive to the underlying GPD dynamics through BSA and cross section measurements. The Double DVCS (DDVCS) process promises a dedicated mapping of GPDs. Contributing to the electro-production of a lepton pair cross-section, the DDVCS reaction extends DVCS by allowing the final-state photon to be virtual, enriching the kinematic phase space and providing unique access to the internal correlations encoded by GPDs. A feasibility study is conducted to assess the potential of future DDVCS measurements at Jefferson Lab and the future Electron-Ion Collider (EIC). While Jefferson Lab will provide DDVCS measurements in the valence region through the SoLID$\mu$ and $\mu$CLAS12 experimental projects, in the long term, the EIC will provide complementary measurements in the sea region, both accessing unprecedented information about GPDs in a phase space region otherwise inaccessible. Taken together, these investigations demonstrate both the current capabilities and future opportunities for probing GPDs through exclusive processes. The experimental analysis of DVCS at CLAS12 provides precise measurements within an established framework, while the phenomenological study of DDVCS opens the door to richer and more comprehensive explorations with future detectors and facilities.

Alvarado, Juan [Université Paris-Saclay: Gif-sur-Y↗
DOE OSTI2019

A visco-plastic framework for interface processes in sedimentary reservoir rocks at HPHT conditions

As energy operations face the challenge of reservoirs at ever-increasing depths, modelling the response of reservoir rocks at high pressure and high temperature (HPHT) conditions is a crucial step for successfully unlocking new resources. At these conditions, rocks can experience thermal and pressure sensitivity, as well as admit internal phase changes at the pore-solid interfaces that determine their macroscopic response to external loading. It is therefore expected that constitutive laws of Geomechanics should be enriched to accommodate such effects. In this work, a multi-physics constitutive theory for sedimentary rocks is proposed within the general framework of viscoplasticity. The viscosity of the material is assumed to be a function of the temperature, pore-pressure and energy required to alter the inter-granular interfaces. This energy is expressed through the chemical potentials of the phases involved during processes like chemical dissolution/precipitation of the interfaces or mechanical debonding. The resulting flow law and corresponding stress equilibrium are coupled to the energy and mass conservation laws, constituting a closed system of equations, which is solved using the Finite Element simulator REDBACK. A series of numerical tests for performance and calibration is then successfully performed against different types of reservoir rocks, confining pressures and temperatures (from room temperature to over 800K). Here, we show that the mechanical response of sedimentary porous rocks at strains usually achieved in laboratory testing can be explained by accounting for the interface processes taking place at the cementitious material bonding the grains, a process that can also determine the brittle-to-ductile transition of sedimentary rocks.

58 GEOSCIENCES↗
DOE OSTI2019

Crystallization Behavior of Liquid CaO-SiO{sub 2}-FeO-MnO Slag in Relation to Its Reaction with Moisture

To help maintain the sustainability of the steel industry, we are developing a novel process to recover thermal energy (in the form of hydrogen) and valuable metal elements contained in steelmaking slags by reacting molten slags with moisture. The process is dependent on the structure and properties of the slag, of which the crystallization tendency is key, since surface phases affect the slag reactivity with the gas and enable selective formation of solid phases containing transition metals. In this paper, the precipitated phases of the molten synthetic CaO-SiO{sub 2}-FeO-MnO slags after reacting with moisture were calculated by using thermodynamic package FactSage 7.0. Laboratory experiments were conducted to reveal the crystallization behavior of the targeted metal oxides in the slags with the aim of crystallization control. A hot stage-equipped confocal laser scanning microscope (CLSM) was used to in-situ observe the crystal precipitation on the surface of the liquid slag after reacting with moisture. Time temperature transformation (TTT) and continuous cooling transformation (CCT) diagrams were created from the precipitation behavior of crystals during cooling in the temperature range of 1873 K to 1173 K (1600 °C to 900 °C). The microstructures of the reacted slags were analyzed with a scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer (EDS) and the phases present in the slag were characterized by X-ray diffraction (XRD). TTT curves of the reacted slags (with moisture) indicated that the nose temperature and critical time for nucleation located at 1473 K (1200 °C) and 89 seconds for the slag with basicity of 1.00. Further increasing the slag basicity to 1.25 and 1.50 increased the nose temperature to 1523 K and 1698 K (1250 °C and 1425 °C), respectively. CCT curves of the reacted slags (with moisture) indicated that the crystallization temperatures of precipitated phases increased with decreasing the cooling rate from 800 to 10 K/min, and the crystallization temperatures of primary phases increased with increasing slag basicity. Both magnetite (Fe{sub 3}O{sub 4}) and monoxide ((FeO){sub x}(MnO){sub 1−x}) phases were detected by SEM-EDS and XRD in the reacted slags (with moisture). The amount of magnetite in the reacted slags increased from 25 to 32 pct to 36 pct and that of monoxide decreased from 5 to 2 pct to 1 pct with the slag basicity increasing from 1.00 to 1.25 to 1.50.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Texture Evolution During Laser Direct Metal Deposition of Ti-6Al-4V

Titanium alloys are used in a wide variety of high performance applications and hence the processing of the titanium and the resulting microstructures after additive manufacturing has received significant attention. During additive manufacturing the processing route involves the transition from a liquid to solid state. The addition of successive layers results in a complex microstructure due to solid-state transformations. The current study focuses on understanding the phase transformations and relate it to the transformation texture in Ti-6Al-4V to identify conditions leading to a strong alpha transformation texture. The as deposited builds were characterized using optical microscopy and electron backscattered diffraction. The results showed columnar prior β grains with a martensitic structure after the deposition of a single layer. On subsequent depositions the martensitic microstructure decomposes to a colony and basketweave microstructure with a stronger transformation texture. The alpha texture with a colony and basketweave microstructure shows a stronger transformation texture as a result of variant selection. Thus by controlling the cooling rate of the build from the β transus it is possible to control the alpha transformation texture.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Design, Synthesis, and Characterization of Polymer Precursors to Li x PON and Li x SiPON Glasses: Materials That Enable All-Solid-State Batteries (ASBs)

LiPON-like glasses that form lithium dendrite impenetrable interfaces between lithium battery components are enabling materials that may replace liquid electrolytes permitting production of all-solid-state batteries (ASBs). Unfortunately, to date, such materials are introduced only via gas-phase deposition. Furthermore, we demonstrate the design and synthesis of easily scaled, lowtemperature, low-cost, solution-processable inorganic polymers containing LiPON/LiSiPON elements. OPCl 3 and hexachlorophosphazene [Cl 2 P=N] 3 provide starting points for elaboration using MNH 2 (M = Li/Na) or (Me 3 Si)NH followed by reaction with controlled amounts of LiNH 2 to produce oligomers/polymers with molecular weights (MWs) ≈1–2 kDa characterized by multinuclear NMR, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), Fourier-transform infrared (FTIR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and matrix-assisted laser desorption/ ionization (MALDI)-time-of-flight (ToF) offering stabilities to 150–200 °C and ceramic yields (800 °C) of 50–60%. 7 Li NMR suggests that precursor-bound Li + dissociates easily, beneficial for electrochemical applications. XPS shows higher N/P ratios (1–3) than via gas-phase methods (<1) correlating N/P ratios, 7 Li shifts, and Li + conductivities. Li 2 SiPHN offers the highest ambient conductivity of 3 × 10 –1 mS cm –1 at 400 °C/2 h/N 2 .

36 MATERIALS SCIENCE↗
DOE OSTI2017

Integrating solids and gases for attosecond pulse generation

Here, control of the field of few-cycle optical pulses has had an enormous impact on attosecond science. Subcycle pulses open the potential for non-adiabatic phase matching while concentrating the electric field so it can be used most efficiently. However, subcycle field transients have been difficult to generate. We exploit the perturbative response of a sub-100 µm thick monocrystalline quartz plate irradiated by an intense few-cycle 1.8 µm pulse, which creates a phase-controlled supercontinuum spectrum. Within the quartz, the pulse becomes space–time coupled as it generates a parallel second harmonic. Vacuum propagation naturally leads to a subcycle electric-field transient whose envelope is sculpted by the carrier envelope phase of the incident radiation. We show that a second medium (either gas or solid) can generate isolated attosecond pulses in the extreme ultraviolet region. With no optical elements between the components, the process is scalable to very high energy pulses and allows the use of diverse media.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Polymorphism and phase transitions in Na 2 U 2 O 7 from density functional perturbation theory

Polymorphism and phase transitions in sodium diuranate, Na 2 U 2 O 7 , are investigated with density functional perturbation theory (DFPT). Thermal properties of crystalline α-, β- and γ-Na 2 U 2 O 7 polymorphs are predicted from DFPT phonon calculations, i.e., the first time for the high-temperature γ-Na 2 U 2 O 7 phase (R$\bar{3}$ with combining macron]m symmetry). The standard molar isochoric heat capacities predicted within the quasi-harmonic approximation are C p (298.15K)= 219.4 and 220.9 J K -1 mol -1 mfor P21/a α-Na 2 U 2 O 7 and C2/m β-Na 2 U 2 O 7 , respectively. Gibbs free energy calculations reveal that α-Na 2 U 2 O 7 (P2 1 /a) and β-Na 2 U 2 O 7 (C2/m) are almost energetically degenerate at low temperature, with β-Na 2 U 2 O 7 becoming slightly more stable than α-Na 2 U 2 O 7 as temperature increases. Here these findings are consistent with XRD data showing a mixture of α and β phases after cooling of γ-Na 2 U 2 O 7 to room temperature and the observation of a sluggish α → β phase transition above ca. 600 K. A recently observed α-Na 2 U 2 O 7 structure with P21 symmetry is also shown to be metastable at low temperature. Based on Gibbs free energy, no direct β → γ solid-solid phase transition is predicted at high temperature, although some experiments reported the existence of such phase transition around 1348 K. This, along with recent experiments, suggests the occurrence of a multi-step process consisting of initial β-phase decomposition, followed by recrystallization into γ-phase as temperature increases.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Enzymatic reduction of U60 nanoclusters by Shewanella oneidensis MR-1

Abstract In this study, a series of reduction experiments were conducted using a representative uranyl peroxide nanocluster, U60 (K 16 Li 44 [UO 2 (O 2 )OH] 60 ) and a bacterial species, Shewanella oneidensis MR-1 , that is capable of enzymatic U(VI) reduction. U60 was reduced by S. oneidensis in the absence of O 2 , but the reduction kinetics for U60 were significantly slower than was observed in this study for aqueous uranyl acetate, and were faster than was reported in previous studies for solid phase U(VI). Our results indicate that U60 aggregates bigger than 0.2 μm formed immediately upon mixing with the bacterial growth medium, and that these aggregates were gradually broken down during the process of reduction. Neither reduction nor dissolution of U60 was observed during 72 h of control experiments open to the atmosphere, indicating that the breakdown and dissolution of U60 aggregates is caused by the reduction of U60, and that S. oneidensis is capable of direct reduction of the U(VI) within the U60 nanoclusters, likely due to the adsorption of U60 aggregates onto bacterial cells. This study is first to show the reduction capacity of bacteria for uranyl peroxide nanoclusters, and the results yield a better understanding of the long term fate of uranium in environmental systems in which uranyl peroxide nanoclusters are present.

nuclear (including radiation effects), materials a↗
DOE OSTI2019

Glass-Ceramic Material Modeling

Glass-ceramics are a unique class of materials in which the growth of a ceramic phase(s) may be induced in an inorganic glass resulting in a microstructurally heterogeneous material with both glass and ceramic phases. This specialized processing is often referred to as "ceramming''. A wide variety of such materials have been developed through the use of different initial glass compositions and thermomechanical processing routes and that have enabled applications in dentistry, consumer kitchenware, and telescopes mirrors. These materials may also exhibit large apparent coefficients of thermal expansion making them attractive for consideration in glass-ceramic seals. These large apparent coefficients of thermal expansion often arise from silica polymorphs, such as cristobalite, undergoing a solid-to-solid phase transformations producing additional non-linearity in the effective material response.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Evaluation of Equiatomic CrMnFeCoNiCu System and Subsequent Derivation of a Non-Equiatomic MnFeCoNiCu Alloy

Investigation into non-equiatomic high-entropy alloys has grown in recent years due to questions about the role of entropy stabilization in forming single-phase solid solutions. Non-equiatomic alloys have been shown to retain the outstanding mechanical properties exhibited by their equiatomic counterparts and even improve electrical, thermal, and magnetic properties, albeit with relaxed composition bounds. However, much remains to understand the processing–structure–property relationships in all classes of so-called high-entropy alloys (HEAs). Here, we are motivated by the natural phenomena of crystal growth and equilibrium conditions to introduce a method of HEA development where controlled processing conditions determine the most probable and stable composition. This is demonstrated by cooling an equiatomic CrMnFeCoNiCu alloy from the melt steadily over 3 days (cooling rate ~4 °C/h). The result is an alloy containing large Cr-rich precipitates and an almost Cr-free matrix exhibiting compositions within the MnFeCoNiCu system (with trace amounts of Cr). From this juncture, it is argued that the most stable composition is within the CrMnFeCoNiCu system rather than the CrMnFeCoNi system. With further optimization and evaluation, a unique non-equiatomic alloy, Mn 17 Fe 21 Co 24 Ni 24 Cu 14 , is derived. The alloy solidifies and recrystallizes into a single-phase face-centered cubic (FCC) polycrystal. In addition to possible applications where Invar is currently utilized, this alloy can be used in fundamental studies that contrast its behavior with its equiatomic counterpart and shed light on the development of HEAs.

36 MATERIALS SCIENCE↗
DOE OSTI2016

A survey of chemical separation in accreting neutron stars

The heavy element ashes of rp-process hydrogen and helium burning in accreting neutron stars are compressed to high density where they freeze, forming the outer crust of the star. We calculate the chemical separation on freezing for a number of different nuclear mixtures resulting from a range of burning conditions for the rp-process. We confirm the generic result that light nuclei are preferentially retained in the liquid and heavy nuclei in the solid. This is in agreement with the previous study of a 17-component mixture of rp-process ashes by Horowitz et al., but extends that result to a much larger range of compositions. We also find an alternative phase separation regime for the lightest ash mixtures which does not demonstrate this generic behavior. With a few exceptions, we find that chemical separation reduces the expected Q{sub imp} in the outer crust compared to the initial rp-process ash, where Q{sub imp} measures the mean-square dispersion in atomic number Z of the nuclei in the mixture. We find that the fractional spread of Z plays a role in setting the amount of chemical separation and is strongly correlated to the divergence between the two/three-component approximations and the full component model. The contrast in Y {sub e} between the initial rp-process ashes and the equilibrium liquid composition is similar to that assumed in earlier two-component models of compositionally driven convection, except for very light compositions which produce nearly negligible convective driving. We discuss the implications of these results for observations of accreting neutron stars.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Qualification of Processing Batches for Tank Closure Cesium Removal Through In-Tank Batch Contact Testing - 20470

The Tank Closure Cesium Removal (TCCR) process at the Savannah River Site (SRS) is currently processing waste from Tank 10H, generating decontaminated salt solution that is sent to Tank 11H. Transfers out of Tank 11H are then disposed of on site as a grout wasteform in the SRS Saltstone Processing Facility. This is a full-scale demonstration of the use of Crystalline Silicotitanate (CST) for the decontamination of aqueous nuclear waste supernate. CST primarily removes cesium from the high sodium alkaline feed, but also adsorbs strontium, actinides, and some other trace metals. The TCCR unit is an at-tank set of four ion exchange columns, with two typically being operated in series during waste processing. Tank 10H is serving a dual function as both the salt dissolution tank as well as the feed tank for the TCCR system. Prior to operation of TCCR, Tank 10H must undergo dissolution campaigns, dissolving the salt cake to form an aqueous salt solution (supernate). After each dissolution campaign, the supernate created must be qualified prior to processing through the TCCR system. Qualification includes detailed characterization of the supernate as well as in-tank batch contact tests to determine the equilibrium loading of Cs-137 on the CST ion exchange media (IONSIV{sup TM} R9120-Ba). In support of the in-tank batch contact testing, Savannah River National Laboratory (SRNL) developed a CST sample holder, also referred to as a 'tea-bag', to hold a measured amount (∼0.1 grams) of pretreated CST between stainless steel screens. The tea-bag fits within a standard stainless steel sample vial that has been modified to allow the flow of supernate to the CST. This sample holder is then immersed in the waste tank allowing free contact between the CST beads and the surrounding liquid, at an effectively infinite liquid-to-solid phase ratio. A pair of tea-bags are deployed in the tank for a period of 10 days for each batch, after which the CST is recovered, digested, and analyzed to determine the loading of cesium isotopes on the CST. This result then supports the TCCR column thermal loading limits for processing as part of the TCCR safety basis. This paper will discuss the design and testing of the CST sample holder, as well as results from the first few batches of waste qualified and subsequently processed through the TCCR system. In addition, results from analyses of Tank 11H samples, showing decontamination of the product will be included. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2026

Conversion of real-world aluminum scrap streams into high-performance Al–Mg–Si–Cu automotive alloys using shear assisted processing and extrusion

The conversion of post-consumer aluminum (Al) scrap into usable Al alloys without adding primary Al is challenging because of excess impurities. In this work, >99% post-consumer Twitch, used beverage cans (UBCs), and remelt scrap ingots (RSIs) were used as feedstock materials. As-cast and solution heat-treated feedstock billets were extruded using Shear Assisted Processing and Extrusion (ShAPE) at ~510°C, followed by press quenching. To explore the development of the microstructure, texture, and underlying mechanisms and how they contribute to the overall strengthening in as-extruded and artificially aged samples, scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) were used to collect microstructure and texture data. The enhanced strength and ductility were corroborated with the microstructural features and crystallographic texture. Simple shear $\textrm{A}/\bar{\textrm{A}}$, $\textrm{A}_1^*/\textrm{A} _2^*$ texture components along with weak $\textrm{C}$ and $\textrm{B}/\bar{\textrm{B}}$ texture components were formed during extrusion; the texture was strengthened after heat treatment. The refined second-phase particles helped to retain the deformed microstructure and texture. The contributions of dislocation and precipitate strengthening were maximized when billets were solution-heat-treated prior to extrusion. This is attributed to the formation of effective supersaturated solid solutions during the ShAPE process, which precipitate out during the peak age treatment. Overall, the highest yield strength of 305 MPa, ultimate tensile strength of 350 MPa, and elongation of 12% were achieved in artificially aged samples, which are comparable to those of Al 6082-T6.

Al alloy↗
DOE OSTI2025

Pushing the Limits: Maximizing Energy Density in Silicon Sulfide Solid‐State Batteries

Here, for the first time, we demonstrate a silicon solid-state battery (SSB) architecture that achieves >400 Wh kg −1 , approaching the theoretical limit for silicon-based SSBs. This configuration features a 99.9 wt% micro-Si, a thin sulfide solid electrolyte (SSE), and a high-loading NMC811. Key to these results is strategically selecting and evaluating the processing techniques, whether wet or dry, for the negative electrode, positive electrode and thin sheet-type SSE. Excessive lithium incorporation into the silicon host, beyond the Li 3.75 +Si phase to form a LiSi composite, is essential to match the high capacity of the positive electrode. This SSB achieves over 1000 cycles for a 2 mAh cm −2 with ≈80% capacity retention and 94% capacity retention for 3 mAh cm −2 over 500 cycles at 25 °C. Post analysis identifies the primary capacity decay mechanisms as oxidation at the NMC/SSE interface and structural disruptions within NMC. Meanwhile, the Si electrode maintains a robust solid-electrolyte interphase layer, minimizing capacity decay. This study highlights the necessity for improved NMC coatings, lattice oxygen stabilization, and a durable positive electrode-electrolyte interface to improve the long-term stability of SSBs. Strategies leading to a single-layer pouch cell SSB exceeding 400 Wh kg −1 are developed.

25 ENERGY STORAGE↗
DOE OSTI2019

Effects of 3d electron configurations on helium bubble formation and void swelling in concentrated solid-solution alloys

Currently, elemental specific chemical complexity is known to play a vital role in microstructure development in single-phase concentrated solid-solution alloys (SP-CSAs), including both He bubble formation and irradiation-induced void swelling. While cavity formation and evolution under ion irradiation at elevated temperature are complex nonequilibrium processes, chemical effects are revealed at the level of electrons and atoms herein in a simplified picture, using Ni and a special set of Ni-based SP-CSAs composed of 3d transition metals as model alloys. Based on Ni and the model alloys with minimized variables (e.g., atomic mass, size, and lattice structure), we report on the effects of chemically-biased energy dissipation, defect energetics, sluggish diffusion, and atomic transport on cavity formation and evolution under both self-ion Ni irradiation and He implantation. The observed difference in microstructure evolution is attributed to the effects of d electron interactions in their integrated ability to dissipate radiation energy. The exhibited impact of alloying 3d transition metals with larger differences in the outermost electron counts suggests a simple design strategy for tuning defect properties to improve radiation tolerance in structural alloys.

36 MATERIALS SCIENCE↗