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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 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Development of constitutive models for cyclic plasticity and creep behavior of super alloys at high temperature

An uncoupled constitutive model for predicting the transient response of thermal and rate dependent, inelastic material behavior was developed. The uncoupled model assumes that there is a temperature below which the total strain consists essentially of elastic and rate insensitive inelastic strains only. Above this temperature, the rate dependent inelastic strain (creep) dominates. The rate insensitive inelastic strain component is modelled in an incremental form with a yield function, blow rule and hardening law. Revisions to the hardening rule permit the model to predict temperature-dependent kinematic-isotropic hardening behavior, cyclic saturation, asymmetric stress-strain response upon stress reversal, and variable Bauschinger effect. The rate dependent inelastic strain component is modelled using a rate equation in terms of back stress, drag stress and exponent n as functions of temperature and strain. A sequence of hysteresis loops and relaxation tests are utilized to define the rate dependent inelastic strain rate. Evaluation of the model has been performed by comparison with experiments involving various thermal and mechanical load histories on 5086 aluminum alloy, 304 stainless steel and Hastelloy X.

Haisler, W. E.↗
NASA NTRS2018

Design and Development of CubeSat Solar Array Deployment Mechanisms Using Shape Memory Alloys

The Advanced eLectrical Bus (ALBus) project is a technology demonstration mission of a 3U CubeSat with an advanced, digitally controlled electrical power system capability and the novel use of Shape Memory Alloy (SMA) technology for reliable solar array (SA) deployable mechanisms. The ALBus CubeSat deploys four SAs in addition to the body-mounted arrays on each side of the CubeSat. A goal of the mission is to utilize the SMAs being developed at the NASA Glenn Research Center to deploy these SAs. The use of SMAs allows for the ability to test and reset the flight deployment mechanism prior to flight, which reduces the risk of in orbit deployment failures common to CubeSats. As a result, an SMA-driven Retention and Release (R&R) mechanism and an SMA-driven hinge were designed, developed, and integrated for flight. This paper summarizes the development of these mechanisms, types and functionalities of the SMAs used, as well as the lessons learned throughout the process.

cubesat↗
NASA NTRS2002

Cryogenic Fracture Toughness Improvement for the Super Lightweight Tank's Main Structural Alloy

Marshall Space Flight Center has developed a two-step (TS) artificial aging technique that can significantly enhance cryogenic fracture toughness and resistance to stress corrosion cracking (SCC) in aluminum-copper-lithium alloy 2195. The new TS aging treatment consists of exposures at 132 C (270 F)/20 hr + 138 C (280 F)/42 hr, which can be readily applied to flight hardware production. TS aging achieves the same yield strength levels as conventional aging, while providing much improved ductility in the short transverse direction. After TS aging, five previously rejected lots of alloy 2195 (lots 950M029B, 960M030F, 960M030J, 960M030K, and 960M030L) passed simulated service testing for use in the super lightweight tank program. Each lot exhibited higher fracture toughness at cryogenic temperature than at ambient temperature. Their SCC resistance was also enhanced. All SCC specimens passed the minimum 10-day requirement in 3.5-percent sodium chloride alternate immersion at a stress of 45 ksi. The SCC lives ranged from 57 to 83 days, with an average of 70 days.

Chen, P. S.↗
DOE OSTI2025

DEVELOPMENT OF INEXPENSIVE HIGH TEMPERATURE NITI-BASED SHAPE MEMORY ALLOYS FOR POWDER BED ADDITIVE MANUFACTURING

NiTi and NiTi-based Shape Memory Alloys (SMA) exhibit a reversible solid-state phase transformation from martensite to austenite driven by thermal energy. High temperature (Mf>100°C) SMAs are martensite at room temperature and can be fabricated into solid-state actuators that return to a pre-programmed shape against a designed load after heating to transformation threshold. Reactive as-fabricated additively manufactured parts (4-D printing) is the current state of the art in manufacturing of SMAs but requires compositions compliant to rapid solidification. Existing actuator designs are developed from commercially available, highly investigated material compositions. However, existing high temperature high performance (high actuation strain, low thermal hysteresis) shape memory alloys contain significant (>10% at.) portions of high-cost Platinum Group Metals (PGMs). It is of significant scientific interest to investigate material compositions that are peer performing or superior to PGMs whose constituent elements represent a significant cost savings. Shape memory alloy properties vary significantly with small (0.1% at.) compositional changes making robust investigative sample sets very large. Computational material design can be deployed to shrink the compositional space of possible alloy combinations and reduce the experimental load in material discovery. Investigating shape memory effect (SME) and validating process additive process parameters for a single novel composition is cost intensive in both time and consumed materials. Additionally, sub-optimal processing, oxygen, or solidification rate sensitivity could render additively manufacturing specimens without micro, macro cracks, or significant chemical variance impossible. Unfortunately, such failure susceptibility cannot be simulated. Therefore, a research pathway to validate novel shape memory alloy compositions for powder bed fusion additive manufacturing without the need for powdered feedstock is also proposed. This research investigates novel high temperature shape memory alloys for actuators without platinum group alloying elements to discover one that could be commercially viable as an additive manufacturing feedstock.

Sundermann, Tayler↗
DOE OSTI2024

Fatigue and Creep-Fatigue Evaluation of Alloy 709 at 760 and 816°C

A significant research and development effort is underway to support the qualification of Alloy 709 as a Class A construction material in the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section III, Division 5, High Temperature Reactors. This initiative includes a comprehensive Alloy 709 code qualification plan aimed at generating extensive material testing data crucial for compiling the code case data package. The data package is essential in establishing material-specific design parameters for Alloy 709 to be used as Section III, Division 5 Class A construction material for fast reactors, molten salt reactors and gas-cooled reactors. An ASME Section III, Division 5 material code case requires the evaluation of mechanical properties from a minimum of three commercial heats, covering anticipated compositional ranges. A key part of the data package involves fatigue and creep-fatigue testing at elevated temperatures, needed for developing the fatigue design curves and the damage envelope of the creep-fatigue interaction diagram (D-diagram). This paper summarizes the strain-controlled fatigue testing on three commercial heats of Alloy 709 at 760 and 816°C with strain ranges between 0.25% and 3%. The fatigue failure data are used to generate a preliminary fatigue design curve. Additionally, the creep-fatigue testing results at 816°C with tensile hold times of 10, 30, and 60 minutes are presented in support of developing the D-diagram for Alloy 709.

Wang, Yanli↗
NASA NTRS2018

Design and Development of CubeSat Solar Array Deployment Mechanisms Using Shape Memory Alloys

The Advanced eLectrical Bus (ALBus) project is a technology demonstration mission of a 3-U CubeSat with an advanced, digitally controlled electrical power system capability and the novel use of Shape Memory Alloy (SMA) technology for reliable solar array deployable mechanisms. The ALBus cubesat has a need to deploy four solar arrays in addition to the body-mounted arrays on each side of the cubesat. A goal of the mission is to utilize the SMAs being developed at the NASA Glenn Research Center to deploy these solar arrays. The use of SMAs allows for the ability to test and reset the flight deployment mechanism prior to flight which reduces the risk of on orbit deployment failures common on cubesats. As a result, an SMA driven Retention and Release mechanism and an SMA driven hinge was designed, developed, and being prepared for flight. This paper summarized the development of these mechanisms, types and functionalities of SMAs used, and lessons learned throughout the process.

solar array deployment↗
DOE OSTI2023

Toward the design of ultrahigh-entropy alloys via mining six million texts

Abstract It has long been a norm that researchers extract knowledge from literature to design materials. However, the avalanche of publications makes the norm challenging to follow. Text mining (TM) is efficient in extracting information from corpora. Still, it cannot discover materials not present in the corpora, hindering its broader applications in exploring novel materials, such as high-entropy alloys (HEAs). Here we introduce a concept of “context similarity" for selecting chemical elements for HEAs, based on TM models that analyze the abstracts of 6.4 million papers. The method captures the similarity of chemical elements in the context used by scientists. It overcomes the limitations of TM and identifies the Cantor and Senkov HEAs. We demonstrate its screening capability for six- and seven-component lightweight HEAs by finding nearly 500 promising alloys out of 2.6 million candidates. The method thus brings an approach to the development of ultrahigh-entropy alloys and multicomponent materials.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Magnetostrictive materials for enhanced sensors and electronic components

Magnetostriction is a property of magnetic materials that causes them to change their shape or dimensions when their magnetization changes. Low-cost, mechanically robust magnetostrictive sensors would be valuable for a wide range of applications addressing DOE's energy, environmental, and national security missions. Several examples include monitoring internal conditions of pipelines, enhancing implantable systems for the human body, and improving the electrical grid by providing real time sensors for detecting high impedance faults that may act as ignition sources for forest fires. Historically, magnetostrictive materials tended to be expensive and mechanically brittle, but recent developments in iron-based alloys, especially those that include dilute solutions of rare earth elements, have demonstrated useful magnetostriction values, mechanical robustness, and low costs. This project investigated addition of dilute cerium doping on the magnetostrictive properties of Fe-Ga and Fe-Al alloys. Advanced manufacturing techniques were applied to these materials to take advantage of rapid cooling of the alloy to stabilize desired phases and to make near net shape coupons. These coupons develop significant texturing, offering a route to target microstructures with exceptional performance.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Multi-Pass Hybrid Laser Arc Welding of Alloy 740H

The presentation reviews the progress made toward reducing the joining time of an advanced nickel-based alloy, Alloy 740H by a factor of two using a novel two step fusion welding approach. In the first step, a high powered laser is used to rapidly join thick weld groove lands (~10-12 mm thick) during a single pass. Hybrid laser arc welding (HLAW) is then used to fill the remaining weld groove and complete the joint. This sequential process also utilizes laser wobble in both steps to reduce welding defects and refine the weld microstructure to obtain improved properties compared to conventional gas tungsten or gas metal arc welds, GTAW and GMAW, respectively. The creep behavior of laser-only thick weld groove land welds and HLAW welds were found to be the same or slightly improved compared to conventional GMAW or GTAW welds in this alloy. Creep tests have been started to verify the long-term creep behavior (~10,000 hrs) of these welds. Modeling results on deep penetration laser welding are presented and the initial simulations of laser welding with laser wobble are shown. The next phase of the project will combine the two processes to make complete welds - deep penetration laser welds of thick weld groove lands followed by rapid filling of the remaining weld groove by HLAW - in thick plates (32 mm thick) Alloy 740H plate and entails development of narrow weld groove welding to further decrease the joining time of this alloy.

36 MATERIALS SCIENCE↗
NASA NTRS1988

Ignition characteristics of the iron-based alloy UNS S66286 in pressurized oxygen

The development of ignition and combustion in pressurized oxygen atmospheres was studied for the iron based alloy UNS S66286. Ignition of the alloy was achieved by heating the top surface of a cylindrical specimen with a continuous-wave CO2 laser. Two heating procedures were used. In the first, laser power was adjusted to maintain an approximately linear increase in surface temperature. In the second, laser power was periodically increased until autoheating (self-heating) was established. It was found that the alloy would autoheat to destruction from temperatures below the solidus temperature. In addition endothermic events occurred as the alloy was heated, many at reproducible temperatures. Many endothermic events occurred prior to abrupt increases in surface temperature and appeared to accelerate the rate of increase in specimen temperature to rates greater than what would be expected from increased temperature alone. It is suggested that the source of these endotherms may increase the oxidation rate of the alloy. Ignition parameters are defined and the temperatures at which these parameters occur are given for the oxygen pressure range of 1.72 to 13.8 MPa (25 to 2000 psia).

Bransford, James W.↗
NASA NTRS1989

Ignition characteristics of the nickel-based alloy UNS N07718 in pressurized oxygen

The development of ignition and combustion in pressurized oxygen atmospheres was studied for the nickel based alloy UNS N07718. Ignition of the alloy was achieved by heating the top. It was found that the alloy would autoheat to destruction from temperatures below the solidus temperature. In addition, endothermic events occurred as the alloy was heated, many at reproducible temperatures. Many endothermic events occurred prior to abrupt increases in surface temperature and appeared to accelerate the rate of increase in specimen temperature. It appeared that the source of some endotherms may increase the oxidation rate of the alloy. Ignition parameters are defined and the temperatures at which these parameters occur are given for the oxygen pressure range of 1.72 to 13.8 MPa (250 to 2000 psia).

Bransford, James W.↗
DOE OSTI2025

Developing reliable machine learning interatomic potential for Fe–Cr–Ni austenitic alloys

Gaining atomistic understanding of mechanical behavior of heat-resistant structural materials such as Fe–Cr–Ni-based alloys requires an approach with an accuracy close to density functional theory (DFT) that considers the intrinsic properties of the bulk lattice and important defects such as stacking faults, grain boundaries, and surfaces. This work aims to develop reliable machine learning interatomic potential (MLIAP) at cross-scale for Fe–Cr–Ni ternary alloys with a focus on the face-centered-cubic (fcc) solid solution structure. Leveraging the advantages of moment tensor potentials, which typically necessitate a relatively small training dataset and enable rapid calculations using the large-scale atomic/molecular massively parallel simulator package, we ensure the stability and accuracy of the trained potentials. Important defects such as stacking faults, grain boundaries, and surfaces for wide-range compositions are investigated. Structural, thermal, elastic, and defect properties are determined from molecular dynamics simulations comprising several thousand atoms, generated via canonical Monte Carlo simulations guided by the trained potential. The trained potential allows efficient atomic simulations of structural, thermal, and mechanical properties of fcc Fe–Cr–Ni solid solution alloys as a function of composition and temperature. Therefore, the MLIAP approach represents a major advancement from DFT calculations that are limited to small simulation sizes and traditional molecular dynamics simulations using relatively low accuracy potentials. Furthermore, this work outlines a practical foundation for further investigating the structural evolution and mechanical behavior of austenitic stainless steel and nickel-based alloys in a wide array of applications in extreme environments.

Crystal structure↗
DOE OSTI2020

Magnesium Technology 2020

Magnesium and its alloys are being investigated widely for applications that require extraordinarily high strength-to-weight ratio, vibration damping, electromagnetic shielding, reduction in carbon footprint, sustainability improvements, and low toxicity. In the past decade or so, this drive has led to increased adoption of magnesium and its alloys in everyday products and it is no longer regarded as an esoteric material. The overarching goal of its widespread adoption and replacement of conventional materials such as steel and aluminum alloys has been restricted because of the cost of the material, limited sources of primary material, alloying constraints, high chemical reactivity, and challenges associated with its plasticity. Researchers, scientists, engineers, and economists from industry, government agencies and laboratories, and academic institutions alike are actively developing roadmaps for next-generation products and addressing these challenges as quickly as possible through unique and innovative methods. The TMS Magnesium Committee has been actively involved in providing a platform to these entities for disseminating the latest information, developments, and cutting-edge research and development, and showcasing the latest research and development trends related to magnesium and its alloys through the Magnesium Technology Symposium, which takes place every year at the TMS Annual Meeting. This proceedings volume retains the essence of this longstanding tradition. The twenty-first volume in the series, Magnesium Technology 2020, is the proceedings of the Magnesium Technology Symposium held during the 149th TMS Annual Meeting & Exhibition in San Diego, CA, February 23–27, 2020. The volume captures commentaries and papers from 15 different countries. The papers have been categorized systematically based on topics pertaining to magnesium production, casting and solidification, thermomechanical processing, deformation mechanisms, modeling, corrosion, and applications. The symposium began with keynote sessions that featured several distinguished invited speakers from government organizations and academia, who provided their perspectives on the state of the art, goals, and opportunities in magnesium alloy research and development. Dr. Carlos Tomé from Los Alamos National Laboratory, U.S. Department of Energy, discussed 3D characterization of mechanical twins across grain boundaries. This was followed by a talk on hierarchically structured ultrafine-grained magnesium alloys by Dr. Rajiv Mishra from the University of North Texas, USA, who presented an example of using friction stir additive manufacturing for implementing such microstructures at a component level. Dr. Mark Horstemeyer from Liberty University, USA, presented an overview of fatigue modeling to capture the corrosion-fatigue behavior of magnesium alloys. The final talk in this session was presented by Dr. Bin Jiang from Chongqing University, China, who presented a novel extrusion approach for achieving high-strength magnesium alloy plates.

Jordon, J. Brian↗
DOE OSTI2020

Cooling dynamics of two titanium alloys during laser powder bed fusion probed with in situ X-ray imaging and diffraction

Metal parts produced by laser powder bed fusion (LPBF) additive manufacturing exhibit characteristic microstructures comparable to those observed in laser welding. The primary cause of this characteristic microstructure is rapid, localized heating and cooling cycles, which result in extreme thermal gradients where material solidification is followed by fast cooling in the solid state. The final microstructure and mechanical performance are also influenced by pore formation caused by melt pool fluid dynamics. Here, we use high speed, in situ X-ray diffraction to probe the kinetics of cooling and solid-solid phase transitions after laser melting in two aerospace titanium alloys: Ti-6Al-4V, an α + β alloy; and Ti-5Al-5V-5Mo-3Cr, a near-β alloy. We complement these diffraction studies with in situ X-ray imaging to probe melt pool dynamics and pore formation. From these two complementary probes, we quantify pore formation during melting and the subsequent microstructural evolution as the material rapidly cools after solidification. These results are critical for understanding defect formation and residual stress development in different titanium alloys under LPBF conditions and can help inform process models to predict final part performance.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Stimulating β -Series Precipitation in Mg–Nd Alloys Via Microalloying: A Comparison of Electron Microscopy and Small-Angle Scattering Techniques

The Mg–Nd alloy system is of particular interest in the development of high-strength, lightweight structural alloys due to the formation of strengthening metastable Mg–Nd β-series precipitates during heat treatment. The strengthening is primarily provided by a combination of the β''' and β 1 precipitation. It is therefore important to understand how the precipitation behavior can be enhanced by other common alloying elements. In this work, the effects of 0.2 wt pct Zn and Ca on β-series precipitation were studied. Small-angle/ultra-small-angle X-ray scattering (SAXS/USAXS) techniques in combination with scanning transmission electron microscopy (STEM) were used to study the evolution of precipitation microstructure. Here, it is found that the Zn additions refine the precipitates, leading to an increase in hardness with aging at 200 °C. On the other hand, the Ca additions result in an acceleration in the formation of larger β 1 precipitates and chains which provides less strengthening. The β 1 chains are surrounded by precipitate-free zones (PFZs) that further contribute to the decreases in hardness observed in the over-aged condition. This paper demonstrated that SAXS/USAXS provides a powerful tool for an in situ study of the early stages of precipitation in the Mg–Nd-based alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Effect of Si impurities on microstructure and tensile properties of a cast Al-Mg-Fe alloy

Al-Mg alloys are attractive for structural castings owing to their superior strength and ductility in the as-cast state. However, given the tight tolerance for impurities, Al-Mg alloys produced from secondary sources still face multiple challenges. Here, we report the effect of increased Si impurity (0.05–1.6 wt%), which is commonly found in secondary Al sources, on microstructure and tensile properties of a cast Al-4.3Mg-1.6Fe (wt%) alloy, commercially referred to as Castaduct-42 alloy. Microstructural characterization revealed that Si addition increased the volume fraction, size, and aspect ratio of primary Al13Fe4 intermetallic particles as well as the volume fraction of other binary and ternary eutectic phases. Tensile testing results demonstrated that increasing Si impurities from 0.05 to 1.6 wt% reduced ductility from 14.3 ± 1.4 % to 2.2 ± 1.0 %. A particle cracking damage accumulation model coupled with failure analysis indicated primary Al13Fe4 intermetallic particles to be the major contributing factor to the deterioration in ductility with increasing Si content. Additionally, the stabilizing effect of Si on primary Al 13 Fe 4 was inconsistent with the CALPHAD calculation results based on existing CALPHAD databases which predict a slightly decreasing primary Al13Fe4 phase fraction with increasing Si concentration. This work provides new insights into the phase stability and mechanical behavior of the lesser studied Al-Mg-Fe-Si alloy system that will contribute to the development of sustainable cast Al-Mg based alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2023

g-factor engineering with InAsSb alloys toward zero band gap limit

Band gap is known as an effective parameter for tuning the Landé g factor in semiconductors and can be manipulated in a wide range through the bowing effect in ternary alloys. In this work, using the recently developed virtual substrate technique, high-quality InAsSb alloys throughout the whole Sb composition range are fabricated and a large g factor of g≈-90 at the minimum band gap of ~0.1 eV, which is almost twice that in bulk InSb, is found. Further analysis to the zero gap limit reveals a possible gigantic g factor of g≈-200 with a peculiar relativistic Zeeman effect that disperses as the square root of magnetic field. Such a g-factor enhancement toward the narrow gap limit cannot be quantitatively described by the conventional Roth formula, as the orbital interaction effect between the nearly triply degenerated bands becomes the dominant source for the Zeeman splitting. These results may provide insights into realizing large g factors and spin-polarized states in semiconductors and topological materials.

36 MATERIALS SCIENCE↗
NASA NTRS1982

Applications of high-temperature powder metal aluminum alloys to small gas turbines

A program aimed at the development of advanced powder-metallurgy (PM) aluminum alloys for high-temperature applications up to 650 F using the concepts of rapid solidification and mechanical alloying is discussed. In particular, application of rapidly solidified PM aluminum alloys to centrifugal compressor impellers, currently used in auxiliary power units for both military and commercial aircraft and potentially for advanced automotive gas turbine engines, is examined. It is shown that substitution of high-temperature aluminum for titanium alloy impellers operating in the 360-650 F range provides significant savings in material and machining costs and results in reduced component weight, and consequently, reduced rotating group inertia requirements.

Millan, P. P., Jr.↗