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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

The Parameterization of Solid Metal-Liquid Metal Partitioning of Siderophile Elements

The composition of a metallic liquid can significantly affect the partitioning behavior of elements. For example, some experimental solid metal-liquid metal partition coefficients have been shown to increase by three orders of magnitude with increasing S-content of the metallic liquid. Along with S, the presence of other light elements, such as P and C, has also been demonstrated to affect trace element partitioning behavior. Understanding the effects of metallic composition on partitioning behavior is important for modeling the crystallization of magmatic iron meteorites and the chemical effects of planetary differentiation. It is thus useful to have a mathematical expression that parameterizes the partition coefficient as a function of the composition of the metal. Here we present a revised parameterization method, which builds on the theory of the current parameterization of Jones and Malvin and which better handles partitioning in multi-light-element systems.

Chabot, N. L.↗
NASA NTRS2004

Solid Metal-Liquid Metal Partitioning of Pt, Re, and Os: The Effect of Carbon

If the measured Os isotopic ratios are a signature from the Earth's outer core, understanding them is a unique opportunity to understand more about the Earth's core. The distribution of elements between the Earth's solid inner core and the liquid outer core will depend on their solid metal-liquid metal partition coefficients (D). Solid metal-liquid metal partitioning data are loosely consistent with the needed fractionations between Re-Os and Pt-Os to account for the Os isotopic signature; D(Os) is greater than both D(Re) and D(Pt), and the magnitude of the partition coefficients are similar to those needed [e.g. 7, 8]. The pressure in the core, the composition of the core, and the crystal structure of the solid Fe alloy in the inner core may influence the specific values of the partition coefficients. It may thus be possible to use these sensitivities of the partition coefficients to gain insight into the conditions within the Earth's core. In this abstract, we focus on the compositional influence of C, a potential component of the light element in the Earth's core [9], on the partitioning behaviors of Pt, Re, and Os.

Chabot, N. L.↗
DOE OSTI2022

HIDRA-MAT liquid metal droplet injector for liquid metal applications in HIDRA

A liquid metal droplet injector was explicitly designed for the Hybrid Illinois Device for Research and Applications Material Analysis Test-stand (HIDRA-MAT) at the University of Illinois Urbana-Champaign to prepare liquid metal plasma-facing components (PFCs) for plasma exposure. The design goals were to create a compact, reliable, and robust design that could apply liquid metal droplets in-vacuo to a variety of samples. The injector was designed for liquid metal use, and results discussed pertain to lithium. The injector can produce lithium droplets of consistent size by utilizing programmable piston movement. Here, droplet formation data is presented for four different piston step sizes (0.125 mm, 0.25 mm, 0.5 mm, and 1 mm) at three different nozzle temperatures (185 °C, 230 °C, and 270 °C). Droplets are formed on the injector nozzle tip and a linear shift mechanism vertically translates the droplet to the substrate for application. This design prevents the droplet from inadvertently detaching off the nozzle and falling to the sample. Application of the liquid metal droplet ensures placement consistency on the substrate and helps avoid damage to components in HIDRA-MAT that should not interact with liquid metals. A description of the liquid lithium droplet creation and application results is given and provides additional insight into the cooling and oxidation of lithium droplets under vacuum conditions. A second nozzle was fabricated and demonstrated repeatability in droplet diameter creation having a variance of ±0.14 mm for droplets created from the same number of piston steps. The end-use for the injector on HIDRA-MAT is to apply liquid metals to PFCs and expose them to HIDRA's plasma with subsequent intershot in-vacuo surface analysis in HIDRA-MAT for plasma-material interaction studies.

42 ENGINEERING↗
NASA NTRS1984

Theory of the spin-1 bosonic liquid metal - Equilibrium properties of liquid metallic deuterium

The theory of a two-component quantum fluid comprised of spin-1/2 fermions and nonzero spin bosons is examined. This system is of interest because it embodies a possible quantum liquid metallic phase of highly compressed deuterium. Bose condensation is assumed present and the two cases of nuclear-spin-polarized and -unpolarized systems are considered. A significant feature in the unpolarized case is the presence of a nonmagnetic mode with quadratic dispersion owing its existence to nonzero boson spin. The physical character of this mode is examined in detail within a Bogoliubov approach. The specific heat, bulk modulus, spin susceptibility, and thermal expansion are all determined. Striking contrasts in the specific heats and thermal-expansion coefficients of the liquid and corresponding normal solid metallic phase are predicted.

Oliva, J.↗
NASA NTRS1981

Two-component Fermi-liquid theory - Equilibrium properties of liquid metallic hydrogen

It is reported that the transition of condensed hydrogen from an insulating molecular crystal phase to a metallic liquid phase, at zero temperature and high pressure, appears possible. Liquid metallic hydrogen (LMH), comprising interpenetrating proton and electron fluids, would constitute a two-component Fermi liquid with both a very high component-mass ratio and long-range, species-dependent bare interactions. The low-temperature equilibrium properties of LMH are examined by means of a generalization to the case of two components of the phenomenological Landau Fermi-liquid theory, and the low-temperature specific heat, compressibility, thermal expansion coefficient and spin susceptibility are given. It is found that the specific heat and the thermal expansion coefficient are vastly greater in the liquid than in the corresponding solid, due to the presence of proton quasiparticle excitations in the liquid.

Oliva, J.↗
DOE OSTI2023

A liquid metal dropper for experiments on the wettability of liquid metals on plasma facing components

A liquid metal dropper has been developed as a part of the Ion-Gas-Neutral Interactions with Surfaces 2 (IGNIS-2) facility at The Pennsylvania State University. The dropper has the capability of directly applying drops to candidate plasma facing materials for nuclear fusion reactors to enable measurements of their liquid metal wetting properties. The results presented here are specific to the use of lithium in the dropper. This paper discusses the design choices of the liquid metal dropper and its chamber, including the heating and temperature control and the dropper’s motorized operation. Lithium drops of masses ranging from 0.05 g up to 0.13 g, equivalent to drop diameters between 5.6 mm to 1 cm, have been consistently dispensed by the dropper. A new algorithm is developed and used to automate the analysis of the contact angle between the liquid drops and substrate material for efficient analysis of video data recorded to study the wetting properties of candidate plasma-facing components.

Instruments & Instrumentation↗
DOE OSTI2018

Pattern formation during electrochemical and liquid metal dealloying

Dealloying has evolved from a problematic corrosion process to a versatile tool for scalable fabrication of nanostructured metals. While the original, and majority of, work in the area has focused on electrochemical dealloying, a powerful variation of dealloying—liquid metal dealloying—has recently gained popularity. This process relies on a melt to carry out selective dissolution, replacing the traditional electrolyte solution. While electrolytes and molten metals are both suitable dealloying media, they can lead to very different morphologies. In this article, we compare and contrast what is known about the microscale physics and chemistry controlling microstructural evolution in electrochemical and liquid metal dealloying. Here, we conclude that the core phenomenology of porosity evolution—a competition between dissolution and interface diffusion—is similar in both dealloying processes, but that the relative magnitudes of these two processes control interfacial pattern formation.

McCue, Ian↗
DOE OSTI2019

Dramatic effect of oxide on measured liquid metal rheology

Liquid metals have traditionally been treated as Newtonian liquids, but several researchers have recently suggested that some metals may shear thin. While apparent shear thinning can be caused by surface oxidation, the reports of shear-thinning metals were investigated using cup and bob type rheometers, which are expected to only be weakly impacted by the surface contamination effects. We show here that even small amounts of oxide on the surface of liquid metals can cause dramatic changes to the measured viscosity of the sample. Using a Searle-type rotational rheometer, we measured the viscosity of eutectic gallium indium and tin in a low-oxygen environment. When either metal is slightly oxidized, the measured viscosity increases by orders of magnitude and the liquid displays erroneous shear-thinning behavior. When the oxide is removed via an active flux, the measured viscosity is Newtonian. The findings outlined here provide insight into the difficulties of measuring the viscosity of easily oxidized liquids and confirm that liquid metals are likely best described as Newtonian liquids at all measured shear rates.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Structural crossover in a supercooled metallic liquid and the link to a liquid-to-liquid phase transition

Time-resolved synchrotron measurements were carried out to capture the structure evolution of an electrostatically levitated metallic-glass-forming liquid during free cooling. The experimental data shows a crossover in the liquid structure at ~1000 K, about 115 K below the melting temperature and 150 K above the crystallization temperature. The structure change is characterized by a dramatic growth in the extended-range order below the crossover temperature. Molecular dynamics simulations have identified that the growth of the extended-range order was due to an increased correlation between solute atoms. These results provide structural evidence for a liquid-to-liquid-phase-transition in the supercooled metallic liquid.

Glass transitions↗
DOE OSTI2015

Topology-generating interfacial pattern formation during liquid metal dealloying

Liquid metal dealloying has emerged as a novel technique to produce topologically complex nanoporous and nanocomposite structures with ultra-high interfacial area and other unique properties relevant for diverse material applications. This process is empirically known to require the selective dissolution of one element of a multicomponent solid alloy into a liquid metal to obtain desirable structures. However, how structures form is not known. Here we demonstrate, using mesoscale phase-field modelling and experiments, that nano/microstructural pattern formation during dealloying results from the interplay of (i) interfacial spinodal decomposition, forming compositional domain structures enriched in the immiscible element, and (ii) diffusion-coupled growth of the enriched solid phase and the liquid phase into the alloy. We highlight how those two basic mechanisms interact to yield a rich variety of topologically disconnected and connected structures. Furthermore, we deduce scaling laws governing microstructural length scales and dealloying kinetics.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Electrical detector for liquid metal leaks

A liquid metal leak detector system including a direct current (DC) power supply and a plurality of analog to digital converters connected to the DC power supply. Each converter includes a liquid metal switch, where the liquid metal switch is closed in event of a liquid metal leak since the liquid metal leak causes electrical continuity between a conductive sheeting and a housing for liquid metal. The converter also includes a comparator connected to both the liquid metal switch for converting an analog signal into a digital signal, wherein the digital signal is configured such that a high signal constitutes no leak and a low signal constitutes a leak. An AND gate is also connected to each of the plurality of converters for combining all of the digital signals output from the converters, the AND gate configured such that the AND gate outputs a high signal if all of its inputs are high and a low signal if any input is low.

42 ENGINEERING↗
DOE OSTI2017

Three-Dimensional Morphological and Chemical Evolution of Nanoporous Stainless Steel by Liquid Metal Dealloying [3D Morphological and Chemical Evolution of Nanoporous Stainless Steel by Liquid Metal Dealloying]

Nanoporous materials, especially those fabricated by liquid metal dealloying processes, possess great potential in a wide range of applications due to their high surface area, bicontinuous structure with both open pores for transport and solid phase for conductivity or support, and low material cost. Here, we used X-ray nanotomography and X-ray fluorescence microscopy to reveal the three-dimensional (3D) morphology and elemental distribution within materials. Focusing on nanoporous stainless steel, we evaluated the 3D morphology of the dealloying front and established a quantitative processing-structure-property relationship at a later stage of dealloying. The morphological differences of samples created by liquid metal dealloying and aqueous dealloying methods were also discussed. Here, we concluded that it is particularly important to consider the dealloying, coarsening, and densification mechanisms in influencing the performance-determining, critical 3D parameters, such as tortuosity, pore size, porosity, curvature, and interfacial shape.

36 MATERIALS SCIENCE↗
NASA NTRS1964

Liquid-metal technology

Liquid metal technology for high temperature heat transfer, working fluid, and electrical applications

WORKING FLUID↗
DOE OSTI2019

Liquid Metal Diagnostics

Liquid metal (LM) plasma-facing components (PFCs) (LM-PFCs) within next-generation fusion reactors are expected to enhance plasma confinement, facilitate tritium breeding, improve reactor thermal efficiency, and withstand large heat and particle fluxes better than solid components made from tungsten, molybdenum, or graphite. Some LM divertor concepts intended for long-pulse operation at >20 MW/m 2 incorporate thin (~1 cm), fast-moving (~5 to 10 m/s), free-surface flows. Such systems will require a range of diagnostics to monitor and control the velocity, flow depth, temperature, and impurity concentration of the LM. As such, this paper will highlight technologies developed for the fission and casting/metallurgical industries that can be adapted to meet the needs of LM-PFC research. This paper is divided into four major parts. The first part will look at noncontact flowmeter technologies that are suitable for high-temperature alkali metal systems. These technologies include rotating Lorentz-force flowmeters for bulk flow rate measurements and particle tracking techniques for surface velocity measurements. Second, this paper will detail the operation of a new inductive level sensor that can be used within free-surface LM-PFCs. This robust level sensor can be mounted below the substrate that supports the LM, so it is simple to install and is protected from the damaging conditions inside a fusion reactor. It has been shown that this level sensor can be calibrated using either numerical or experimental techniques. Third, distributed temperature sensors based on fiber-optic technologies will be discussed. This advanced measurement technique provides temperature data with high spatial resolution and has recently been successfully tested in LM systems. Last, diagnostics to measure impurity concentration, such as electrochemical cells, plugging meters, and spectroscopic systems, will be addressed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Self-assembled porous metal-intermetallic nanocomposites via liquid metal dealloying

A major challenge in the synthesis of high surface area metals via subtractive processes such as dealloying is maintaining the mechanical integrity of the resulting porous materials. This issue is especially apparent in liquid metal dealloying, in which high-temperature selective dissolution in a molten metal bath leads to bicontinuous porosity formation. In liquid metal dealloying of polycrystalline alloys, grain boundary separation leads to the detachment of individual grains. In this work, we show that addition of small amounts of silicon to Nbsingle bondTi or Tasingle bondTi parent alloys leads to the generation of self-assembled arrays of intermetallic (niobium silicide or tantalum silicide) plates that are structurally merged with the usual bicontinuous porosity seen in dealloying. These silicide plates pass through grain boundaries and hold the niobium or tantalum network intact without strongly affecting the microstructural evolution during dealloying. Our approach yields a mechanically robust porous metal-intermetallic composite, which can be further processed to form tertiary materials via re-impregnation by a new third phase. The materials design strategy introduced here can be generalized to serve as a platform to form dense multiphase nanocomposites.

36 MATERIALS SCIENCE↗