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Phase stability and transformation in a light-weight high-entropy alloy
Light-weight high-entropy alloys (HEAs) with a vast alloy-design space have offered new avenues to explore novel low-cost, high strength-to-weight ratio structural materials. Studying their phase stability and possible transformations is critical for designing microstructures for optimal material properties. However, the complex local atomic environment of HEAs poses challenges to the fundamental understanding of phase stability and transformation behaviors. The present paper investigates the phase stability and transformation behaviors of a newly-designed light-weight Al 1.5 CrFeMnTi HEA by integrated experimental and theoretical approaches. The coherent precipitation of the L2 1 phase within the body-centered-cubic (BCC) matrix at intermediate temperatures was observed, and the size, shape, coherency, and spatial distribution of the L2 1 phase were subsequently altered through selected annealing treatments. Moreover, the CALculation of PHAse Diagrams (CALPHAD) and first-principle calculations successfully optimize the compositions of light-weight HEAs with a coherent BCC/L2 1 two-phase structure. Finally, shed light by the present study, novel light-weight HEAs, featuring the lower density (below 6 g/cm 3 ) and cost, can be designed for high-temperature applications.
Design of Light-Weight High-Entropy Alloys
High-entropy alloys (HEAs) are a new class of solid-solution alloys that have attracted worldwide attention for their outstanding properties. Owing to the demand from transportation and defense industries, light-weight HEAs have also garnered widespread interest from scientists for use as potential structural materials. Great efforts have been made to study the phase-formation rules of HEAs to accelerate and refine the discovery process. In this paper, many proposed solid-solution phase-formation rules are assessed, based on a series of known and newly-designed light-weight HEAs. The results indicate that these empirical rules work for most compositions but also fail for several alloys. Light-weight HEAs often involve the additions of Al and/or Ti in great amounts, resulting in large negative enthalpies for forming solid-solution phases and/or intermetallic compounds. Accordingly, these empirical rules need to be modified with the new experimental data. In contrast, CALPHAD (acronym of the calculation of phase diagrams) method is demonstrated to be an effective approach to predict the phase formation in HEAs as a function of composition and temperature. Future perspectives on the design of light-weight HEAs are discussed in light of CALPHAD modeling and physical metallurgy principles.
A New Light Weight Structural Material for Nuclear Structures
Radiation shielding materials are commonly used in nuclear facilities to attenuate the background ionization radiations to a minimum level for creating a safer workplace, meeting regulatory requirements and maintaining high quality performance. The conventional radiation shielding materials have a number of drawbacks: heavy concrete contains a high amount of elements that are not desirable for an effective shielding such as oxygen, silicon, and calcium; a well known limitation of lead is its low machinability and toxicity, which is causing a major environmental concern. Therefore, an effective and environmentally friendly shielding material with increased attenuation and low mass density is desirable. Close-cell composite metal foams (CMFs) and open-cell Al foam with fillers are light-weight candidate materials that we have studied in this project. Close-cell CMFs possess several suitable properties that are unattainable by conventional radiation shielding materials such as low density and high strength for structural applications, high surface area to volume ratio for excellent thermal isolation with an extraordinary energy absorption capability. Open-cell foam is made up of a network of interconnected solid struts, which allows gas or fluid media to pass through it. This unique structure provided a further motive to investigate its application as radiation shields by infiltrating original empty pores with high hydrogen or boron compounds, which are well known for their excellent neutron shielding capability. The resulting open-cell foam with fillers will not only exhibit light weight and high specific surface area, but also possess excellent radiation shielding capability and good processability. In this study, all the foams were investigated for their radiation shielding efficiency in terms of X-ray, gamma ray and neutron. X-ray transmission measurements were carried out on a high-resolution microcomputed tomography (microCT) system. Gamma-emitting sources: 3.0mCi 60 Co, 1.8mCi 137 Cs, 13.5mCi 241 Am, and 5.0mCi 133 Ba were used for gamma-ray attenuation analysis. The evaluations of neutron transmission measurements were conducted at the Neutron Powder Diffractometer beam facility at North Carolina State University. The experimental results were verified theoretically through XCOM and Monte Carlo Z-particle Transport Code (MCNP). A mechanical investigation was performed by means of quasi-static compressive testing. Thermal characterizations were carried out through effective thermal conductivity and thermal expansion analyses in terms of high temperature guarded-comparative-longitudinal heat flow technique and thermomechanical analyzer (TMA), respectively. The experimental results were compared with analytical results obtained from, respectively, Brailsford and Major’s model and modified Turner’s model for verification. Flame test was performed in accordance with United States Nuclear Regulatory Commission (USNRC) standard. CMF sample and a 304L stainless steel control sample were subjected to a fully engulfing fire with an average flame temperature of 800°C for a period of 30 minutes. Finite Element Analysis was conducted to secure the credibility of the experimental results. This research indicates the potential of utilizing the light-weight close-cell CMFs and open-cell Al foam with fillers as shielding material replacing current heavy structures with additional advantage of high-energy absorption and excellent thermal characteristics.
Specific Energy Analysis for the Manufacturing of Light-Weight Automobile Body
This manuscript analyses the specific energy requirements to produce two hybridised vehicle structures on current automotive assembly lines. It provides quantitative and specific electric (kWhr/vehicle) and fossil-fuel (MMBtu/vehicle) energy predictions of the body-in-white (BIW) manufacturing processes including body panel forming, welding, painting, and final assembly, in addition to the facility heating ventilation and air conditioning or HVAC consumption. Two hybridised BIW design criteria are analysed; the first is based on minimising the added cost per unit weight saved (+$/-kg), while the second is based on maximising the percentage of weight saved (% -kg). Also a new criterion; that is the added specific-energy per unit weight-saved or (+kWhr/vehicle/-kg) is proposed. The light-weight structures comprise body parts made of aluminium and steel. To compute energy consumptions, the study utilises the energy performance index (EPI) stochastic model in addition to complementing it with a panel-forming energy model. Cost analysis is also provided for all the major vehicle body-panels using an in-house Excel macro. The study reverse engineers a passenger vehicle BIW using a full-size coordinate measuring machine (CMM). The presented work further highlights the monetary value of the associated emissions when increasing the specific energy.
Light-weight analyzer for odor recognition
The invention provides a light weight analyzer, e.g., detector, capable of locating clandestine graves. The detector utilizes the very specific and unique chemicals identified in the database of human decompositional odor. This detector, based on specific chemical compounds found relevant to human decomposition, is the next step forward in clandestine grave detection and will take the guess-work out of current methods using canines and ground-penetrating radar, which have historically been unreliable. The detector is self contained, portable and built for field use. Both visual and auditory cues are provided to the operator.
Overview of Light Weight Radioisotope Heater Unit (LWRHU) User’s Guide
Idaho National Laboratory (INL) has recently compiled a user’s guide for the Light Weight Radioisotope Heater Unit (LWRHU). This guide gives an overview of the LWRHU to potential users. Information and data on mass properties, dimensions, thermal loads, and interfaces are discussed.
Toward a Self-calibrating, Empirical, Light-weight Model for Tellurics in High-resolution Spectra
To discover Earth analogs around other stars, next generation spectrographs must measure radial velocity with 10 cm s{sup −1} precision. Since even microtellurics can induce RV errors of up to 50 cm s{sup −1}, achieving 10 cm s{sup −1} precision requires precise modeling of telluric absorption features. The standard approaches to telluric modeling are (a) observing a standard star and (b) using a radiative transfer code. Observing standard stars, however, takes valuable observing time away from science targets. Radiative transfer codes, meanwhile, may omit microtelluric features, which are an important contributor to the RV error budget at 10 cm s{sup −1}. To address these issues, we present a telluric model of the self-calibrating, empirical, light-weight linear regression telluric (SELENITE) model for high-resolution spectra. The model exploits two simple observations: (a) water tellurics grow proportionally to precipitable water vapor and therefore proportionally to each other and (b) non-water tellurics grow proportionally to airmass. Water tellurics can be identified by looking for pixels whose growth correlates with a known calibration water telluric and modeled by regression against it, and likewise non-water tellurics with airmass. The model does not require line data, water vapor measurements, or additional observations (beyond one-time calibration observations), achieves fits with a χ{sub red}{sup 2} of 1.17 on B stars and 2.95 on K dwarfs, and leaves residuals of 1% (B stars) and 1.1% (K dwarfs) of continuum. Fitting takes seconds on laptop PCs; SELENITE is light-weight enough to guide observing runs.
Light Weight Radioisotope Heater Unit User’s Guide
This user's guide provides an overview of Light Weight Radioisotope Heater Units (LWRHU), including aspects of its physical design and performance under normal operations. This guide also identifies the planning and execution involved in launching a nuclear payload. Physical characteristics, interfaces, and environmental characteristics of the LWRHU are discussed in detail. Information relating to project management interfaces and effort.
Comparison of Light-Weight Radioisotope Heater Unit (LWRHU) Historical Testing to Special Form Testing Requirements
This paper compares the Light-Weight Radioisotope Heater Unit (LWRHU) historical testing to Department of Transportation (DOT) Special Form criteria per 49 CFR Part 173, Shippers-General Requirements for Shipments and Packages, Section 469, Tests for special form Class 7 (radioactive) materials as specified in DOE-STD-1027, Hazard Categorization of DOE Nuclear Facilities. Compliance with the aforementioned criteria allows for the exclusion of radioactive sources from the facility’s nuclear material inventory. As part of a new program at Los Alamos National Laboratory (LANL), LWRHUs are planned to be moved into TA-55, PF-5 Power Source Assembly Area (PSAA) for assembly and testing activities. The PSAA Facility is categorized as a low hazard, non-nuclear facility per DOE STD-1027 and is described in TA55-PF-5-FHC-11-001, Facility Hazard Categorization of the PSAA at PF-5, TA-55. The Facility Hazard Categorization document states, there must be documentation that radioactive sources are engineered to pass the special form testing specified by DOT in 49 CFR 173.469, Tests for special form Class 7 (radioactive) materials or ANSI N43.6, Sealed Radioactive Sources - Classification. This paper documents the extensive historical environmental safety testing of the LWRHU and demonstrates its ability to survive potential launch safety accident scenarios. The testing results are used herein to demonstrate through a comparative analysis that the robust design of the LWRHU meets or exceeds the special form testing specifications in 49 CFR 173.469, enabling the LWRHU to be transported and handled in PF-5 in support of testing and assembly program.
Re-establishment of Light-Weight Radioisotope Heater Unit Platinum-30% Rhodium Alloy Components Production at Oak Ridge National Laboratory
During FY2018 the Oak Ridge National Laboratory (ORNL) Radioisotope Power Systems (RPS) Program completed re-establishment of capability to produce platinum-30% rhodium (Pt-30Rh) alloy components for the Light Weight Radioisotope Heater Unit (LWRHU) Program. These components were last produced at Mound Laboratory in the mid/late-1990s for the National Aeronautics and Space Administration (NASA) Cassini mission. The LWRHU Pt-30Rh Clad Body Subassembly and component fabrication operations are being performed in the iridium alloy Clad Vent Set (CVS) production area at ORNL. Existing equipment (furnaces, electron beam welders, presses, inspection, etc.) are being utilized along with new equipment (two lathes and laser marker) that were purchased for this work. ORNL purchased and qualified an initial quantity of starting materials (Pt powder, Pt-30Rh foil, sheet, and tubing). Equipment, tooling, and materials were procured/fabricated and qualified. Drawings and specifications were updated/modified/developed to the ORNL RPS Program format. Procedures were developed and qualified. All drawings, specifications, and procedures were reviewed/approved by the Idaho National Laboratory (INL) RPS Lead Lab Document Configuration Control Board (DCCB). The dimensional inspection operations and special processes (cleaning, heat treating, sintering, dye penetrant inspection, leak testing, and welding) were successfully qualified and documented. This paper will discuss the process of re-establishing LWRHU production at ORNL to provide for future NASA space exploration science mission needs10.
Characterization of Oscillatory Response of Light-Weight Wind Turbine Rotors under Controlled Gust Pulses
Given the industry-wide trend of continual increases in the size of utility-scale wind turbines, a point will come where reductions will need to be made in terms of the weight of the turbine’s blades to ensure they can be as long as needed without sacrificing structural stability. One such technique that may be considered is to decrease the material used for the shell and spar cap. While this will solve the weight issue, it creates a new one entirely—less material for the shell and spar cap will in turn create blades that are more flexible than what is currently used. This article aims to investigate how the oscillatory response of light-weight wind turbine rotors is affected by these flexibility changes. The object of our study is the Sandia National Lab National Rotor Testbed (SNL-NRT) wind turbine, which the authors investigated in the course of a research project supported by SNL. Using a reduced-order characterization (ROC) technique based on controlled gust pulses, introduced by the authors in a previous work, the aeroelastic dynamics of the NRT’s original baseline blade design and several of its flexible variations were studied via numerical simulations employing the CODEF multiphysics suite. Results for this characterization are presented and analyzed, including a generalization of the ROC of the SNL-NRT oscillatory dynamics to larger machines with geometrical similarity. The latter will prove to be valuable in terms of extrapolating results from the present investigation and other ongoing studies to the scale of current and future commercial machines.
Development of Precipitation-Strengthened Al 0.8 NbTiVM (M = Co, Ni) Light-Weight Refractory High-Entropy Alloys
Single-phase solid-solution refractory high-entropy alloys (RHEAs) have been receiving significant attention due to their excellent mechanical properties and phase stability at elevated temperatures. Recently, many studies have been reported regarding the precipitation-enhanced alloy design strategy to further improve the mechanical properties of RHEAs at elevated temperatures. In this study, we attempted to develop precipitation-hardened light-weight RHEAs via addition of Ni or Co into Al 0.8 NbTiV HEA. The added elements were selected due to their smaller atomic radius and larger mixing enthalpy, which is known to stimulate the formation of precipitates. The addition of the Ni or Co leads to the formation of the sigma precipitates with homogeneous distribution. The formation and homogeneous distribution of sigma particles plays a critical role in improvement of yield strength. Furthermore, the Al 0.8 NbTiVM 0.2 (M = Co, Ni) HEAs show excellent specific yield strength compared to single-phase AlNbTiV and NbTiVZr RHEA alloys and conventional Ni-based superalloy (Inconel 718) at elevated temperatures.
A novel imaging technique for measuring kinematics of light-weight flexible structures
A new imaging algorithm is proposed to capture the kinematics of flexible, thin, light structures including frequencies and motion amplitudes for real time analysis. The studied case is a thin flexible beam that is preset at different angles of attack in a wind tunnel. As the angle of attack is increased beyond a critical value, the beam was observed to undergo a static deflection that is ensued by limit cycle oscillations. Imaging analysis of the beam vibrations shows that the motion consists of a superposition of the bending and torsion modes. The proposed algorithm was able to capture the oscillation amplitudes as well as the frequencies of both bending and torsion modes. The analysis results are validated through comparison with measurements from a piezoelectric sensor that is attached to the beam at its root.
Compact, Low-Cost, Light-Weight, Superconducting, Ironless Cyclotrons for Hadron Radiotherapy (Final Report)
This is the final report of a conceptual design study to demonstrate the feasibility of an ironless, superconducting synchrocyclotron for use as a particle accelerator in the clinical treatment of cancer using proton beam radiotherapy (PBRT). Furthermore, the ironless synchrocyclotron approach can be scaled up to accelerate light ions up to carbon, offering significant treatment advantages over conventional proton therapies, and offers a path for more rapid introduction of this technology to clinical uses.
Final Technical Report for the ProNova Solutions contribution to: Compact, low-cost, light-weight, superconducting, ironless cyclotrons for hadron radiotherapy
ProNova Solutions, LLC is a collaborator with the primary PI for this project, Dr. Joseph V. Minervini, Head of the Magnets and Cryogenics group at the Massachusetts Institute of Technology, Plasma Science and Fusion Center. The purpose of the grant was to develop the conceptual design for a superconducting ironless synchrocyclotron suitable for hadron therapy. Such a design could ultimately be extended to light ions such as Helium and Carbon which are being studied at centers around the world. The ProNova efforts have been led by Co-PI Laddie Derenchuk and by Joe Matteo, company president. ProNova efforts will be described in this Final Technical Report, other goals and efforts by the MIT group can be referenced in the MIT Final Technical Report. ProNova’s primary goals as defined in the Project Narrative were to “defin[e] specifications necessary to meet the current and future demands of particle therapy based on ProNova’s clinical experience.” In addition, ProNova was to “focus on ion source, RF, vacuum, and mechanical subsystem conceptual designs”. This report will describe ProNova’s contributions to this project.
Buoyancy can ballast control for increased power generation of a floating offshore wind turbine with a light-weight semi-submersible platform
Not Available
Chemically interconnected light-weight 3D-carbon nanotube solid network
Owing to the weak physical interactions such as van der Waals and π-π interactions, which hold nanotubes together in carbon nanotube (CNT) bulk structures, the tubes can easily slide on each other. In creating covalent interconnection between individual carbon nanotube (CNT) structures we saw remarkable improvements in the properties of their three-dimensional (3D) bulk structures. The creation of such nanoengineered 3D solid structures with improved properties and low-density remains one of the fundamental challenges in real-world applications. We also report the scalable synthesis of low-density 3D macroscopic structure made of covalently interconnected nanotubes using free-radical polymerization method after functionalized CNTs with allylamine monomers. The resulted interconnected highly porous solid structure exhibits higher mechanical properties, larger surface area and greater porosity than non-crosslinked nanotube structures. To gain further insights into the deformation mechanisms of nanotubes, fully atomistic reactive molecular dynamics simulations are used. Here we demonstrate one such utility in CO 2 uptake, whose interconnected solid structure performed better than non-interconnected structures.