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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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15 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Cooling rate and dendrite spacing control in direct metal deposition printed Cu-Fe alloys

Over the last several decades, additive manufacturing (AM) has been primarily used for rapid prototyping or to create novel geometries that would be difficult or impossible to create by normal manufacturing methods. More recently, research has been focused on expanding the list of materials that can be made through additive manufacturing, opening a greater range of material properties for this manufacturing method. Due to the unusual conditions during AM, including the high cooling rates and voxel by voxel method of production, AM parts often have anisotropic material microstructures and properties. In this investigation, the laser power, composition, and nozzle head speed during direct metal deposition of copper-iron alloys was varied to understand how the grain structure within the printed parts could be changed and controlled. The resulting dendrite spacing was measured and compared to calculated cooling rates from Gaussian beams on flat plates under similar material and laser properties, which resulted in a cooling rate to dendrite spacing relationship following an inverse square root, as is found in other dendritic systems [Young and Kerkwood, Metall. Trans. A 6, 197–205 (1975)]. Thus, it is demonstrated that in the Cu-Fe system, dendrite spacing can be controlled through manipulation of printing parameters.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Investigation of Reactivities of Bimetallic Cu-Fe Oxygen Carriers with Coal in High Temperature In-situ Gasification Chemical-Looping Combustion (iG-CLC) and Chemical-Looping with Oxygen Uncoupling (CLOU) Using a Fixed Bed Reactor

This study investigated reduction reactivities and CO2 conversion efficiency of synthesized Fe-Cu-Si OCs for both in-situ gasification CLC (iG-CLC) and Chemical-Looping with Oxygen Uncoupling (CLOU) at high temperatures (950 to 1100°C) with varying ratios of OC to coal char (φ) using a fixed bed reactor-quadrupole mass spectrometer system.

Wang, Ping↗
DOE OSTI2020

Metal-ion-controlled growth and nanoindentation response of 3D, bicontinuous Cu–Fe thin films

Bicontinuous, nanocomposite thin film morphologies depend largely on the deposition conditions applied during physical vapor deposition. With the introduction of high power impulse magnetron sputtering (HiPIMS), the range of potential morphologies achieved during deposition has been increased. In this work, we compare the deposition outcomes between traditional direct-current magnetron sputtering (DCMS) and HiPIMS for a thin film co deposit of Cu and Fe. Modular control of the columnarity, porosity and roughness was achieved by varying the Cu and Fe metal ion currents during deposition. The directionality of the nanostructured phase-separated morphology was also controlled as the ion current increased. At zero ion current for both Cu and Fe sputtered species during DCMS, the film exhibited lateral concentration modulations of Cu and Fe. The directionality of the Cu- and Fe-rich phases shifted to vertical concentration modulations at low ion currents of I Fe = 1A and I Cu = 0:1A and to lateral concentration modulations at relatively moderate ion currents of I Fe = 5A and I Cu = 2A: At high ion currents of I Fe = 18A and I Cu = 2A; a more randomized phase domain structure was observed on the nanoscale. This structural shift is rationalized using an interdiffusion model. Here, the role of different kinds of phase separated morphologies, achieved during DCMS deposition, on the mechanical properties has also been studied. Results indicated increase in hardness, indentation modulus and flow strength values with the increase in indentation strain rates. Bicontinuous Cu-Fe nanocomposites are found to be stronger than multilayer Cu-Fe samples.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Hierarchical morphologies in co-sputter deposited thin films

Co-depositions of immiscible alloy films at specific processing conditions have yielded hierarchical microstructures which consist of distinct features at multiple length scales, often agglomerates and concentration modulations on the sub-micrometer-scale and fine nanoprecipitates in a matrix on the nanoscale. The present work examined a series of immiscible alloy systems: Cu-Mo, Cu-Ag, Cu-Fe, Cu-Ta, Mo-Ag, Cu-Mo-Ag, to determine the kinetic conditions favorable for hierarchical organization and the formation mechanism of such structures. Thin films of six immiscible systems were sputter co-deposited over a range of deposition rates from 0.12 to 2 nm/s and various temperatures from 400 to 800°C. The resulting microstructures indicate that hierarchical structures form with sufficient disparity in kinetic energy between the constituent atoms, one species being highly mobile (A) and the other relatively immobile (B). This condition arises typically at elevated deposition temperatures and reduced deposition rates but is also alloy dependent. The hierarchical structures form during deposition via phase separation and self-organization processes across the multiple length scales. The adatoms diffuse on the film surface with the highly mobile species swiftly agglomerating into A-rich domains within which B-rich nanoprecipitates form, often self-organizing into periodic arrays. The smallest B-rich nanoprecipitates in the A-rich domains are found to be coherent and in a metastable crystal structure (B taking the structure of A), but coarser precipitates that exhibit the equilibrium structure of B element. The A-rich domains are surrounded by a B-rich matrix that phase-separates into a concentration modulated structure. In conclusion, the observations are interpreted via a model incorporating material properties and process parameters.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Modeling of non-equilibrium partitioning in direct metal deposited copper–iron concentrated alloys

The direct metal deposition (DMD) additive manufacturing process produces high cooling rates within a small melt pool and can lead to high amounts of solute trapping. These high cooling rates limit diffusion and lead to the formation of non-equilibrium phases. In this work, we utilize a numerical model to calculate the degree of solute trapping, defined as non-equilibrium partitioning. A theoretical case with overall composition fixed to 50Cu-50Fe at.%. was performed to observe the influence of increasing solidification rates. We then simulate DMD of equimolar Cu-Fe powder printed on mild steel substrate and the calculated non-equilibrium phase compositions were consistent with experimental observations reported earlier on this alloy composition. For a single deposited track, cooling rates are high enough to yield significant solute trapping. Here, the degree of solute trapping is highest near the free surface and has a gradient that correlates with the cooling rate gradient.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Formation Mechanisms, Crystal Structure, and Interfacial Reactivity of (Mixed) Metal Sulfide Nanoparticles Produced via Biological versus Abiotic Systems

The primary goals of this project were to understand the formation mechanisms and reactivity of mix-metal sulfide nanophases (Cu-Fe, Ni-Fe, Co-Fe sulfides) produced via biological and abiotic pathways that are relevant to low-temperature aqueous environments. These mix-metal sulfide nanophases have been identified in a range of natural and anthropogenic systems and are considered to play key roles in the biogeochemical cycling of elements, biomineralization, environmental remediation, resource recovery, eco-toxicity, and the origin and evolution of life. Using a comparative approach, we aimed to elucidate: (i) if these mix-metal sulfides tend to form nanoscale phases regardless of their formation pathways; (ii) what mechanisms are involved in the biological and abiotic crystallization processes; (iii) what phases form that have been otherwise expected; and (iv) if we can combine the experimental results with what we see and surmise from field studies to facilitate a more comprehensive understanding regarding the origin and biogeochemical roles of these mix-metal sulfides. Along a related pathway of electron transfer in nano-systems, in this case dealing with Fe-oxides instead of Fe-sulfides, we have continued to explore the reactions and solid products of heterogeneous catalytic oxidation of aqueous Mn(II) by dissolved oxygen in the presence of iron oxides (hematite) nanoparticles. The nano-Mn-oxides produced are known to be efficient sorbents of transition metal elements, including Cu, Ni, and Co studied in our sulfide work.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Hierarchical microstructures and deformation behavior of laser direct-metal-deposited Cu–Fe alloys

Cu25Fe75 and Cu50Fe50 (nominal composition, at. %) alloys were fabricated using laser direct metal deposition (DMD) based additive manufacturing technique. These alloys exhibit hierarchical microstructures with bi-phasic Cu and Fe dendrites that contain nanoscale precipitates of varying sizes and structures. In the Cu25Fe75 alloy, Fe dendrites contained nanoscale, coherent, metastable BCC Cu and semi-coherent FCC Cu precipitates while the Cu matrix had nanoscale, coherent, metastable FCC Fe precipitates. In the Cu50Fe50 alloy, Fe dendrites only contained nanoscale semi-coherent FCC Cu precipitates while the Cu matrix had nanoscale coherent metastable FCC Fe precipitates. Both alloys exhibited enhanced flow strengths in the range of 750 – 980 MPa and significant plasticity, in compression. Here, the Cu25Fe75 alloy had lower yield strength than Cu50Fe50 alloy but higher maximum compressive strength due to higher strain hardening resulting from slightly coarser dendrites with hierarchy of nanoscale precipitation.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe3Cu by Materials Project

Fe3Cu is Tungsten-derived structured and crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. there are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a distorted body-centered cubic geometry to six Fe and two equivalent Cu atoms. There are four shorter (2.47 Å) and two longer (2.48 Å) Fe–Fe bond lengths. Both Fe–Cu bond lengths are 2.52 Å. In the second Fe site, Fe is bonded in a distorted body-centered cubic geometry to eight Fe atoms. All Fe–Fe bond lengths are 2.47 Å. Cu is bonded in a distorted body-centered cubic geometry to four equivalent Fe and four equivalent Cu atoms. All Cu–Cu bond lengths are 2.47 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe3Cu by Materials Project

Fe3Cu is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. there are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a distorted body-centered cubic geometry to four equivalent Fe and four equivalent Cu atoms. All Fe–Fe bond lengths are 2.43 Å. All Fe–Cu bond lengths are 2.43 Å. In the second Fe site, Fe is bonded in a distorted body-centered cubic geometry to eight equivalent Fe and six equivalent Cu atoms. All Fe–Cu bond lengths are 2.81 Å. Cu is bonded in a distorted body-centered cubic geometry to fourteen Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeCu4 by Materials Project

FeCu4 is alpha La-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Fe is bonded to six equivalent Fe and six equivalent Cu atoms to form FeFe6Cu6 cuboctahedra that share corners with six equivalent FeFe6Cu6 cuboctahedra, corners with six CuCu12 cuboctahedra, edges with six equivalent FeFe6Cu6 cuboctahedra, edges with eighteen CuFe3Cu9 cuboctahedra, faces with six equivalent FeFe6Cu6 cuboctahedra, and faces with twelve equivalent CuFe3Cu9 cuboctahedra. All Fe–Fe bond lengths are 2.55 Å. All Fe–Cu bond lengths are 2.57 Å. There are seven inequivalent Cu sites. In the first Cu site, Cu is bonded to three equivalent Fe and nine Cu atoms to form CuFe3Cu9 cuboctahedra that share corners with twelve CuFe3Cu9 cuboctahedra, edges with six equivalent FeFe6Cu6 cuboctahedra, edges with eighteen CuFe3Cu9 cuboctahedra, faces with six equivalent FeFe6Cu6 cuboctahedra, and faces with twelve CuFe3Cu9 cuboctahedra. There are six shorter (2.55 Å) and three longer (2.56 Å) Cu–Cu bond lengths. In the second Cu site, Cu is bonded to twelve Cu atoms to form CuCu12 cuboctahedra that share corners with three equivalent FeFe6Cu6 cuboctahedra, corners with nine CuFe3Cu9 cuboctahedra, edges with three equivalent FeFe6Cu6 cuboctahedra, edges with twenty-one CuFe3Cu9 cuboctahedra, and faces with eighteen CuFe3Cu9 cuboctahedra. There are six shorter (2.55 Å) and three longer (2.56 Å) Cu–Cu bond lengths. In the third Cu site, Cu is bonded to twelve Cu atoms to form CuCu12 cuboctahedra that share corners with three equivalent FeFe6Cu6 cuboctahedra, corners with nine CuFe3Cu9 cuboctahedra, edges with three equivalent FeFe6Cu6 cuboctahedra, edges with twenty-one CuFe3Cu9 cuboctahedra, and faces with eighteen CuFe3Cu9 cuboctahedra. There are six shorter (2.55 Å) and three longer (2.56 Å) Cu–Cu bond lengths. In the fourth Cu site, Cu is bonded to twelve Cu atoms to form CuCu12 cuboctahedra that share corners with three equivalent FeFe6Cu6 cuboctahedra, corners with nine CuCu12 cuboctahedra, edges with three equivalent FeFe6Cu6 cuboctahedra, edges with twenty-one CuCu12 cuboctahedra, and faces with eighteen CuCu12 cuboctahedra. There are six shorter (2.55 Å) and six longer (2.56 Å) Cu–Cu bond lengths. In the fifth Cu site, Cu is bonded to twelve Cu atoms to form CuCu12 cuboctahedra that share corners with three equivalent FeFe6Cu6 cuboctahedra, corners with fourteen CuCu12 cuboctahedra, edges with three equivalent FeFe6Cu6 cuboctahedra, edges with nineteen CuFe3Cu9 cuboctahedra, and faces with twenty-one CuFe3Cu9 cuboctahedra. There are six shorter (2.55 Å) and six longer (2.56 Å) Cu–Cu bond lengths. In the sixth Cu site, Cu is bonded to sixteen Cu atoms to form CuCu16 cuboctahedra that share corners with three equivalent FeFe6Cu6 cuboctahedra, corners with nineteen CuFe3Cu9 cuboctahedra, edges with three equivalent FeFe6Cu6 cuboctahedra, edges with twenty-one CuFe3Cu9 cuboctahedra, and faces with thirty-four CuCu12 cuboctahedra. There are a spread of Cu–Cu bond distances ranging from 2.55–5.10 Å. In the seventh Cu site, Cu is bonded to three equivalent Fe and nine Cu atoms to form CuFe3Cu9 cuboctahedra that share corners with seventeen CuFe3Cu9 cuboctahedra, edges with six equivalent FeFe6Cu6 cuboctahedra, edges with sixteen CuFe3Cu9 cuboctahedra, faces with six equivalent FeFe6Cu6 cuboctahedra, and faces with fifteen CuCu16 cuboctahedra. All Cu–Fe bond lengths are 2.57 Å. All Cu–Cu bond lengths are 2.55 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe3Cu by Materials Project

Fe3Cu is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Fe sites. In the first Fe site, Fe is bonded to eight Fe and four equivalent Cu atoms to form FeFe8Cu4 cuboctahedra that share corners with twelve equivalent FeFe8Cu4 cuboctahedra, edges with eight equivalent CuFe12 cuboctahedra, edges with sixteen FeFe8Cu4 cuboctahedra, faces with four equivalent CuFe12 cuboctahedra, and faces with fourteen FeFe8Cu4 cuboctahedra. There are four shorter (2.55 Å) and four longer (2.56 Å) Fe–Fe bond lengths. All Fe–Cu bond lengths are 2.55 Å. In the second Fe site, Fe is bonded to eight equivalent Fe and four equivalent Cu atoms to form FeFe8Cu4 cuboctahedra that share corners with four equivalent FeFe8Cu4 cuboctahedra, corners with eight equivalent CuFe12 cuboctahedra, edges with twenty-four FeFe8Cu4 cuboctahedra, faces with six equivalent CuFe12 cuboctahedra, and faces with twelve FeFe8Cu4 cuboctahedra. All Fe–Cu bond lengths are 2.56 Å. Cu is bonded to twelve Fe atoms to form CuFe12 cuboctahedra that share corners with four equivalent CuFe12 cuboctahedra, corners with eight equivalent FeFe8Cu4 cuboctahedra, edges with eight equivalent CuFe12 cuboctahedra, edges with sixteen equivalent FeFe8Cu4 cuboctahedra, faces with four equivalent CuFe12 cuboctahedra, and faces with fourteen FeFe8Cu4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeCu3 by Materials Project

FeCu3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Fe is bonded to twelve equivalent Cu atoms to form FeCu12 cuboctahedra that share corners with six equivalent FeCu12 cuboctahedra, corners with twelve equivalent CuFe4Cu8 cuboctahedra, edges with eighteen equivalent CuFe4Cu8 cuboctahedra, faces with eight equivalent FeCu12 cuboctahedra, and faces with twelve equivalent CuFe4Cu8 cuboctahedra. There are six shorter (2.56 Å) and six longer (2.58 Å) Fe–Cu bond lengths. Cu is bonded to four equivalent Fe and eight equivalent Cu atoms to form CuFe4Cu8 cuboctahedra that share corners with four equivalent FeCu12 cuboctahedra, corners with fourteen equivalent CuFe4Cu8 cuboctahedra, edges with six equivalent FeCu12 cuboctahedra, edges with twelve equivalent CuFe4Cu8 cuboctahedra, faces with four equivalent FeCu12 cuboctahedra, and faces with sixteen equivalent CuFe4Cu8 cuboctahedra. There are a spread of Cu–Cu bond distances ranging from 2.56–2.59 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Phase Transitions of Cu and Fe at Multiscales in an Additively Manufactured Cu–Fe Alloy under High-Pressure

A state of the art, custom-built direct-metal deposition (DMD)-based additive manufacturing (AM) system at the University of Michigan was used to manufacture 50Cu–50Fe alloy with tailored properties for use in high strain/deformation environments. Subsequently, we performed preliminary high-pressure compression experiments to investigate the structural stability and deformation of this material. Our work shows that the alpha (BCC) phase of Fe is stable up to ~16 GPa before reversibly transforming to HCP, which is at least a few GPa higher than pure bulk Fe material. Furthermore, we observed evidence of a transition of Cu nano-precipitates in Fe from the well-known FCC structure to a metastable BCC phase, which has only been predicted via density functional calculations. Finally, the metastable FCC Fe nano-precipitates within the Cu grains show a modulated nano-twinned structure induced by high-pressure deformation. The results from this work demonstrate the opportunity in AM application for tailored functional materials and extreme stress/deformation applications.

36 MATERIALS SCIENCE↗