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At least 1,603 records · Page 89
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Effect of B{sub 2}O{sub 3} Addition on Electrical Conductivity and Structural Roles of CaO-SiO{sub 2}-B{sub 2}O{sub 3} Slag

The effect of B{sub 2}O{sub 3} addition on electrical conductivity of CaO-SiO{sub 2}-B{sub 2}O{sub 3} slag was investigated using the four-electrode method. The slag structure was determined from Raman and nuclear magnetic resonance spectra. The experimental results show that the electrical conductivity, as the B{sub 2}O{sub 3} content in the slag increased from 0 to 10 pct, monotonously increases from 0.0769 to 0.2642 Ω{sup −1} cm{sup −1} at temperatures ranging from 1783 to 1873 K (1510 °C to 1600 °C). The effects of temperature on electrical conductivity obeyed the Arrhenius law, and the electrical conductivity increased as the temperature increased. The Raman spectra results indicated that addition of B{sub 2}O{sub 3} led to an increase of Q{sup 3}(Si) at the cost of Q{sup 2}(Si), which will increase the degree of polymerization of the slag. {sup 11}B nuclear magnetic resonance spectra showed that both BO{sub 3} trigonal and BO{sub 4} tetrahedral structures increased with the increasing B{sub 2}O{sub 3} content. There was a competitive effect between the presence of these structures and an enhanced degree of polymerization of slags in the networks, which resulted in the increased electrical conductivity of the slag. A structure–electrical conductivity model for CaO-SiO{sub 2}-B{sub 2}O{sub 3} slag was established.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effect of Addition of Other Acids into Butyric Acid on Selective Leaching of Zinc from Basic Oxygen Steelmaking Filter Cake

The selective leaching of zinc over iron from basic oxygen steelmaking (BOS) filter cake was investigated using mixtures of butyric acid with acetic and/or propionic acid, HCl, or H{sub 2}SO{sub 4}. The main focus was to assess the effects of other acids on the zinc and iron leaching in butyric acid. The results show that slight reduction of zinc leaching and increase in iron leaching may take place with addition of acetic and propionic acids, causing a minor decrease in the selectivity of zinc leaching over iron. Intermittent addition of H{sub 2}SO{sub 4} and HCl was required to control the pH to be not less than that of pure butyric acid solution. Overall, an excellent selectivity can be maintained with the butyric acid–other acid mixtures. The results demonstrate the feasibility to use raw butyric acid without purification or waste butyric acid containing other impurity acids for leaching of zinc from the BOS filter cake to be recycled. Using high content of H{sub 2}SO{sub 4} in leaching is not recommended because it has a more detrimental effect on the selectivity of zinc leaching and may cause deposition of CaSO{sub 4} in the leaching residue which may increase the SO{sub 2} or CO{sub 2} emission in later high-temperature recycling processes.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effects of the Addition of Micro-amounts of Calcium on the Corrosion Resistance of Mg-0.1Mn-1.0Zn-xCa Biomaterials

Magnesium alloys have good biocompatibility and degradability, which are considered ideal characteristics of biomedical implants. However, there are few studies on the influence of the addition of micro-amounts of Ca on magnesium alloys. In this work, the effects of adding micro-amounts of Ca on the microstructure, mechanical properties, and corrosion properties of Mg-0.1Mn-1.0Zn-xCa (x = 0.1, 0.2, and 0.3 wt.%) alloys were investigated. The results reveal that the grain size of the alloy decreased and the yield strength and elongation both increased with increasing Ca concentrations. Corrosion tests in Kokubo simulated body fluid showed that the in vitro immersion rate first slowed down and then increased (6.395 → 6.283 → 6.395 mm/year) with increasing Ca concentrations. This phenomenon was due to the addition of Ca causing grain refinement, which slowed the corrosion rate and generated an Mg{sub 2}Ca phase to accelerate corrosion. The second-phase Mg{sub 2}Ca precipitated at the grain boundary and acted as a cathode, and the metal magnesium phase acted as an anode to form a primary battery, which caused corrosion of the magnesium phase and accelerated the corrosion rate.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Tensile Properties of a Cast Al-Si-Mg Alloy with Reduced Si Content and Cr Addition at High Temperature

Tensile properties of an Al-Si-Mg casting alloy with reduced Si content and Cr addition were investigated at room and high temperatures. It was found that the studied alloy exhibits a remarkable performance up to 200 °C, with comparable or slightly higher strength than typical values for Al-Si-Mg-Cu alloys, commonly used for high-temperature applications, and good elongation. This is due to the choice of proper heat treatment and to the formation of dispersoids containing Cr during heat treatment, which are stable at the considered temperatures, as demonstrated by scanning and transmission electron microscopy (STEM) analysis. Interestingly, exposure to 300 °C during tensile tests enhanced an additional formation of dispersoids. It is believed that heating the material in T6 condition led to such observed dispersoids formation since precursors were already present in the Al matrix. This is not sufficient to avoid material softening at 300 °C, but it represents an interesting point in order to develop alternative heat treatment routes for dispersion-strengthened Al alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Rapid Solidification and Phase Transformations in Additive Manufactured Materials

Within the past few years, additive manufacturing (AM) has emerged as a promising manufacturing technique to enable the production of complex engineering structures with high efficiency and accuracy. Among the important factors establishing AM as a sustainable manufacturing process is the ability to control the microstructures and properties of AM products. In most AM processes, such as laser sintering (LS), laser melting (LM), and laser metal deposition (LMD), rapid solidification and high-temperature phase transformations play primary roles in determining nano- and microstructures, and consequently the mechanical and other properties of AM products. This topic of JOM is dedicated to summarizing the current research efforts in the area of rapid solidification and phase transformations in additively manufactured materials. Finally, a brief summary follows below of 10 journal articles in this topic.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Defect Identification and Mitigation Via Visual Inspection in Large-Scale Additive Manufacturing

Defect identification and mitigation is an important avenue of research to improve the overall quality of objects created using additive manufacturing (AM) technologies. Identifying and mitigating defects takes on additional importance in large-scale, industrial AM. In large-scale AM, defects that result in failed prints are extremely costly in terms of time spent and material used. To address these issues, researchers at Oak Ridge National Laboratory’s Manufacturing Demonstration Facility investigated the use of a laser profilometer and thermal camera to collect data concerning an object as it was constructed. These data provided feedback for an in situ control system to adjust object construction. Adjustments were made in the form of automated height control. This paper presents results for both a polymer- and metal-based system. Object construction for both systems was improved significantly, and the resulting objects were more geometrically identical to the ideal 3D representation.

42 ENGINEERING↗
DOE OSTI2018

Low-Field Alignment of Anisotropic Bonded Magnets for Additive Manufacturing of Permanent Magnet Motors

Additive manufacturing techniques for fabricating bonded magnets have the potential to reduce manufacturing cost and time-to-market of products and address the criticality of rare-earth elements (REEs), which is a concern for economic design of dependent applications such as permanent magnet machines. We investigated the magnetic alignment of anisotropic bonded magnet material comprising 65 vol.% Nd-Fe-B in nylon-12 produced by extrusion in a 20-W brushless direct current surface permanent magnet motor for submersible water pump application using finite element analysis. The results predict that sufficient alignment for this application could be obtained at low alignment fields (μoH ≤ 1 T) with a reduction in the volume of critical materials by up to 40% compared with isotropic permanent magnets. Furthermore, this demonstrates the economic feasibility of incorporating a magnetic alignment field source into additive manufacturing systems for bonded magnets, and the potential of aligned anisotropic bonded magnets to address REE criticality.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Discontinuous Precipitation in U-10 wt.%Mo Alloy: Reaction Kinetics, Effect of Prior gamma-UMo Microstructure, the Role of Grain-Boundary Misorientation, and the Effect of Ternary Alloying Addition

Eutectoid transformation in U-10 wt.% Mo (U10Mo) alloy initiates through discontinuous precipitation (DP) resulting in the formation of a lamellar microstructure that consists of an a-U and Mo-enriched bcc ?-UMo phase along the prior ?-UMo grain boundaries. DP is the main mode of transformation at 500°C. However, continuous precipitation (CP) of ?’ U2Mo phase together with grain-boundary DP is observed at 400°C. The reaction kinetics are noted to be very sluggish at 400°C compared to 500°C. The degree of eutectoid transformation is related to the prior ?-UMo grain size, and a smaller average grain size leads to a larger amount of transformation at a given reaction temperature. Minor addition (0.2 wt.%) of a third alloying element (Cr, Ni, Co) leads to significant changes in the nature of the DP mechanism in U10Mo alloy. In addition, high-angle grain boundaries with a misorientation of 30–45° are observed to be the major DP initiation sites. The microstructural evolution of U10Mo alloy with regard to DP-based reaction is discussed.

Jana, Saumyadeep↗
DOE OSTI2023

The Addition of Boron to Melt-Spun Fe-6.5%Si Ribbons

Fe-6.5%Si has higher electrical resistivity, lower magnetocrystalline anisotropy, and lower magnetostriction than traditional Fe-3.2%Si silicon steel. The reduced iron losses of Fe-6.5%Si render it a highly favorable candidate for high-speed motors and transformers. However, large-scale production of wide Fe-6.5%Si tape by rapid solidification can be challenging mainly because of its high melting point. In this work, boron is alloyed to Fe-6.5%Si to reduce its melting temperature and interfacial energy to improve the alloy’s processability. Boron additions from 0.01 wt.% to 2.24 wt.% into Fe-6.5%Si and its effect on ribbon thickness, grain size, magnetic, and mechanical properties were studied. Further, minor boron alloying significantly changed the melt pool stability and wetting on the quench wheel and in turn increased the quench rate with minimum impact on the magnetic saturation and ductility. Boron addition of < 0.06 wt.% was also found beneficial to the magnetic property of the alloy by lowering both its hysteresis and eddy current losses.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Image-Based Fracture Surface Defect Characterization Methods for Additively Manufactured Ti-6Al-4V Tested in Fatigue

Abstract Fatigue initiation in additively manufactured samples/parts often occurs at processed-induced defects such as lack-of-fusion (LoF), keyhole, or other morphological/microstructural defects that have unique characteristics and measurable qualities. Attempts at identifying and minimizing such defects have utilized optimized processing conditions along with in situ and ex situ characterization that includes metallography and/or X-ray computed tomography (XCT). This paper highlights the benefits of using fracture surface analyses to detect and quantify defects that may not be detected by metallography/XCT due to sectioning and resolution limits. In addition to using manual quantification of fatigue initiating LoF and keyhole defects on fracture surfaces, image-based machine learning using convolutional neural networks such as U-Net were also used to automate the process. Statistical analyses were used to identify the extreme cases of defects that initiated and accelerated fatigue and to model the distribution of defect size and shape characteristics to distinguish the type of defect. Initial results show agreement between trained machine learning models and ground truth data in defect segmentation, and the distributions of defect characteristics are distinguishable to particular process-induced defect types.

Materials Science↗
DOE OSTI2025

Creep Deformation and Damage Mechanisms in an Advanced High-Temperature Additively Manufactured Nickel-Base Superalloy

Abstract This research investigates the processing–structure–properties–performance relationship in a novel nickel-base superalloy, ABD ® -900AM, designed for extreme environments. Specifically tailored for additive manufacturing (AM), ABD ® -900AM maintains mechanical integrity at high temperatures and is comparable to other nickel-based superalloys with a 30–40% gamma-prime volume fraction. A comprehensive study was conducted using laser-beam powder bed fusion and electron-beam powder bed fusion methods. Factors such as heat treatment, porosity, build orientation, and hot isostatic pressing were evaluated to understand their effects on microstructure and mechanical performance. Microstructural characterization revealed significant differences in grain size and orientation across build processes and heat treatments. High-temperature mechanical testing indicated that grain size, heat treatment, and orientation significantly influence creep behavior. A super-solvus heat treatment led to recrystallization and grain growth, significantly improving creep properties compared to a near-solvus heat treatment. Various creep mechanisms were identified across different conditions, and creep rupture models were developed for each build process. Post-test microstructural analysis showed grain boundary damage, with differences in creep cavitation morphology under varying stress conditions. It was shown that MC carbides grow at the expense of gamma-prime near grain boundaries, leading to precipitate-free zones in specimens tested at higher temperatures. This study fills a significant gap in fundamental research by offering a deeper insight into the high-temperature mechanical behavior of additively manufactured nickel-base superalloys. It also explores critical research questions regarding the role of carbides and the significance of heat treatment. The insights gained enhance confidence in the industry adoption of ABD ® -900AM and similar alloys for high-temperature applications, bridging the knowledge gap and supporting the development of reliable AM processes for extreme environments.

Bridges, Alex (ORCID:000000030338759X)↗
DOE OSTI2025

Mechanical Characteristics of Additively Manufactured ODS 316L and 316H Alloys with and Without Post-build Processing

This research aims to explore an accelerated development path for oxide dispersion-strengthened (ODS) alloys by integrating additive manufacturing (AM) technologies with recent advances in ODS materials and traditional manufacturing methods. Novel AM and post-build processing routes have been developed for ODS austenitic alloys, specifically Fe-Cr-Ni alloys like 316L and 316H. Electron microscopy and mechanical characterizations were conducted to evaluate the effects of process variables on microstructure and properties, aiming for an economically feasible route property optimization. Traditionally, ODS alloy production involves multi-day high-energy mechanical milling of alloy powder with yttria (Y 2 O 3 ) followed by powder consolidation via extrusion or other methods and additional thermomechanical processing (TMP) for property control. Here, to address these challenges associated with this complex and costly approach, we propose exploring alternative, cost-effective processing routes focusing on AM and traditional TMP methods. The new ODS alloy processing routes have achieved up to a 400% increase in yield strength and a 60% increase in ultimate tensile strength compared to wrought stainless steels while still maintaining significant ductility and fracture toughness. This paper details the novel and economical AM-based processing routes for ODS austenitic alloys, combined with post-build TMPs, and discusses the mechanical and microstructural characteristics of the developed materials.

Byun, Thak Sang [Oak Ridge National Laboratory (OR↗
DOE OSTI2025

A Review of the Influence of Processing Parameters on ODS Steels Produced via Additive Manufacturing Techniques

Abstract This paper reviews current observations regarding processing conditions for oxide dispersion-strengthened steels consolidated through additive manufacturing techniques. Variations in ODS steels observed across process parameters include changes in grain size, grain texture, oxide size, density of oxides, porosity, melt pool characteristics, and mechanical properties. These properties were then compared across techniques to understand which techniques and processing conditions lead to the highest strength, ductility, and oxide density. Current literature suggests that a mix of grain types, in the form of either morphology or phase, can significantly increase the strength of printed ODS steels. Meanwhile, the most ductile samples, regardless of consolidation technique or matrix material, were made from feedstock with oxide additions located on the powder surface. Reported grain and oxide sizes were plotted against the ratio of laser power to scan speed, volumetric energy density, and normalized enthalpy. No strong correlation between these values and microstructural features was observed. The plots that were made suggest that a larger data set, more in-depth representative equations, and more defined material properties as a function of specific feedstock used are necessary to determine a value that can be correlated to the printed ODS steel microstructure.

deJong, Matthew↗
DOE OSTI2018

Additively manufactured mixed potential electrochemical sensors for NO x , C 3 H 8 , and NH 3 detection

Additive manufacturing of mixed potential electrochemical sensors opens the possibility to perform rapid prototyping of electrode and electrolyte materials. We report for the first time the use of this technique for the fabrication of solid-state electrochemical gas sensors of the mixed potential type and assessment of variability in the manufacturing process. La 0.87 Sr 0.13 CrO 3 (LSCO) and Pt electrodes bridged with a porous yttria-stabilized zirconia (YSZ) have been deposited on YSZ substrates by direct-write extrusion of pastes and inks. The sensors are evaluated for their sensitivity to 200 ppm of NO x , C 3 H 8 , and NH 3 . There is a need to understand how variations in intrinsic materials parameters during manufacturing such as differences in porosity affect the gas sensing of additively manufactured sensors to guide optimization of their performance and serve as quality control techniques. Further characterizations of these devices include electrochemical impedance spectroscopy and an aqueous electrochemical assessment of the electrode surface area and diffusion through the porous layer. In conclusion, we find a correlation of increased sensitivity with larger gas reaction impedance, higher Pt electrode surface area, and slower diffusion.

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

Emulating the impact of additional proton-proton interactions in the ATLAS simulation by pre-sampling sets of inelastic Monte Carlo events

The accurate simulation of additional interactions at the ATLAS experiment for the analysis of proton-proton collisions delivered by the Large Hadron Collider presents a significant challenge to the computing resources. During the LHC Run (2015-2018) there were up to 70 inelastic interactions per bunch crossing, which need to be accounted for in Monte Carlo (MC) production. In this document, a new method to account for these additional interactions in the simulation chain is described. Instead of sampling the inelastic interactions and adding their energy deposits to a hard-scatter interaction one-by-one, the inelastic interactions are presampled, independent of the hard scatter, and stored as combined events. Consequently, for each hard-scatter interaction only one such presampled event needs to be added as part of the simulation chain. For the Run 2 simulation chain, with an average of 35 interactions per bunch crossing, this new method provides a substantial reduction in MC production CPU needs of around 20%, while reproducing the properties of the reconstructed quantities relevant for physics analyses with good accuracy.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2026

Demonstration and analysis of volumetric additive manufacturing via sub-orbital spaceflight testing

Computed Axial Lithography (CAL) represents a significant advancement in the emerging field of Volumetric Additive Manufacturing (VAM). CAL addresses key limitations of traditional photopolymer additive manufacturing technologies, by eliminating the need for layering and support structures. Unlike conventional methods, CAL prints components by illuminating all points within a desired geometry simultaneously, using tomographic reconstruction to form the object in a single step. This unique approach eliminates the relative motion between the object and the precursor material, enabling faster printing speeds and reducing the waste associated with support structures. However, CAL parts require post-processing steps before they can be utilized. CAL's core attributes make it particularly suited for In-Space Manufacturing (ISM), due to its fast fabrication times, wide breadth of materials it can use, and minimized footprint. CAL has been successfully demonstrated in microgravity during parabolic flight experiments. However to fully validate and understand CAL's behaviour in microgravity, all manufacturing and post-processing steps must be integrated. In June 2024, we conducted SpaceCAL Mission 3, testing this entire workflow on a suborbital flight aboard Virgin Galactic's SpaceShipTwo. During ~140 s of microgravity, the system autonomously manufactured and post-processed four parts using PEGDA700 resin. Post-flight analysis showed that 2/4 parts were recognisable, while others were distorted due to bubble formation from residual water droplets, off-axis optical aberrations, and non-uniform solvent rinsing. Despite these limitations, this study represents the first integrated CAL workflow in space, providing an initial experimental demonstration and analysis for closed-loop in-space manufacturing.

Waddell, Taylor [Department of Mechanical Engineer↗
DOE OSTI2019

Effects of ternary alloy additions on the microstructure of highly immiscible Cu alloys subjected to severe plastic deformation: An evaluation of the effective temperature model

Phase evolution in dilute, strongly immiscible Cu-Mo, Cu-Mo-Ni, and Cu-Mo-Ag alloys during severe plastic deformation at low-temperature has been experimentally investigated. For the Cu95Mo05 alloy, Mo nanoparticles are formed, ~10 nm in diameter, as part of a steady state microstructure, with less than ~1 at.% Mo dissolved in the matrix. Addition of 10 or 20 at.% Ni to this binary alloy results in a significant increase in the Mo solubility, whereas comparable additions of Ag has a corresponding little effect. The steady state microstructures of alloys during ball milling of elemental powders are very similar to those during HPT processing of initially homogeneous solutions. The results are discussed in terms of an effective temperature model. Model MD simulations are presented to help relate the predictions of the effective temperature model to atomistic mechanisms.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Linking pyrometry to porosity in additively manufactured metals

Porosity in additively manufactured metals can reduce material strength which is generally considered undesirable. Although studies have shown relationships between process parameters and porosity, monitoring strategies for defect detection and pore formation are still needed. In this paper, instantaneous anomalous conditions are detected in-situ via pyrometry during laser powder bed fusion additive manufacturing and correlated with voids observed using post-build micro-computed tomography. Large two-color pyrometry data sets were used to estimate instantaneous temperatures, melt pool orientations and aspect ratios. Machine learning algorithms were then applied to processed pyrometry data to detect outlier images and conditions. It is shown that melt pool outliers are good predictors of voids observed post-build. With this approach, real time process monitoring can be incorporated into systems to detect defect and void formation. Alternatively, using the methodology presented here, pyrometry data can be post processed for porosity assessment.

36 MATERIALS SCIENCE↗