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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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6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Quantitative assessment of Ni + and He + ion irradiation damage in a tungsten heavy alloy under the simulated nuclear fusion environment

A 90W-7Ni-3Fe (wt.%) tungsten heavy alloy has been sequentially Ni + and He + ion irradiated at 700 °C to simulate the high temperature irradiation environment of a fusion reactor interior. W/Ni–Fe-W dual-phase alloys have been proposed to serve as plasma facing materials and require detailed investigation of their behavior under fusion relevant conditions to assess their overall applicability. To evaluate material performance under five years of simulated fusion reactor service, microstructural characterization of the nanoscale defect distribution has been performed on both constituent phases, revealing peak swelling in the W phase of approximately 0.03%. The γ-phase (Ni–Fe-W) is found to swell approximately 0.68% under the same irradiation conditions, indicating significant cavity formation and growth. Additionally, a novel multi-projection imaging approach has been applied to determine the extent of damage segregation along the dual-phase W-to-γ interface and exposes that these interfaces act as sink sites for the accumulation of cavities. Interphase boundaries are noted to possess an 11.8% areal coverage of defects along the boundary plane, primarily on the γ-phase side of the boundary. The accumulation of cavities at these interphase boundaries is anticipated to adversely affect overall material toughness, and this work reveals a pressing need for mechanical property testing of irradiated W–Ni-Fe dual-phase alloys.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1983

Electrical characteristics of amorphous iron-tungsten contacts on silicon

The electrical characteristics of amorphous Fe-W contacts have been determined on both p-type and n-type silicon. The amorphous films were obtained by cosputtering from a composite target. Contact resistivities of 1 x 10 to the -7th and 2.8 x 10 to the -6th were measured on n(+) and p(+) silicon, respectively. These values remain constant after thermal treatment up to at least 500 C. A barrier height of 0.61 V was measured on n-type silicon.

Finetti, M.↗
NASA NTRS2013

The W-W02 Oxygen Fugacity Buffer at High Pressures and Temperatures: Implications for f02 Buffering and Metal-silicate Partitioning

Oxygen fugacity (fO2) controls multivalent phase equilibria and partitioning of redox-sensitive elements, and it is important to understand this thermodynamic parameter in experimental and natural systems. The coexistence of a metal and its oxide at equilibrium constitutes an oxygen buffer which can be used to control or calculate fO2 in high pressure experiments. Application of 1-bar buffers to high pressure conditions can lead to inaccuracies in fO2 calculations because of unconstrained pressure dependencies. Extending fO2 buffers to pressures and temperatures corresponding to the Earth's deep interior requires precise determinations of the difference in volume (Delta) V) between the buffer phases. Synchrotron x-ray diffraction data were obtained using diamond anvil cells (DAC) and a multi anvil press (MAP) to measure unit cell volumes of W and WO2 at pressures and temperatures up to 70 GPa and 2300 K. These data were fitted to Birch-Murnaghan 3rd-order thermal equations of state using a thermal pressure approach; parameters for W are KT = 306 GPa, KT' = 4.06, and αKT = 0.00417 GPa K-1. Two structural phase transitions were observed for WO2 at 4 and 32 GPa with structures in P21/c, Pnma and C2/c space groups. Equations of state were fitted for these phases over their respective pressure ranges yielding the parameters KT = 190, 213, 300 GPa, KT' = 4.24, 5.17, 4 (fixed), and αKT = 0.00506, 0.00419, 0.00467 GPa K-1 for the P21/c, Pnma and C2/c phases, respectively. The W-WO2 buffer (WWO) was extended to high pressure by inverting the W and WO2 equations of state to obtain phase volumes at discrete pressures (1-bar to 100 GPa, 1 GPa increments) along isotherms (300 to 3000K, 100 K increments). The slope of the absolute fO2 of the WWO buffer is positive with increasing temperature up to approximately 70 GPa and is negative above this pressure. The slope is positive along isotherms from 1000 to 3000K with increasing pressure up to at least 100 GPa. The WWO buffer is at a higher fO2 than the IW buffer at pressures lower than 40 GPa, and the magnitude of this difference decreases at higher pressures. This qualitatively indicates an increasingly lithophile character for W at higher pressures. The WWO buffer was quantitatively applied to W metal-silicate partitioning by using the WWO-IW buffer difference in combination with literature data on W metal-silicate partitioning to model the exchange coefficient (KD) for the Fe-W exchange reaction. This approach captures the pressure dependence of W metal-silicate partitioning using the WWO-IW buffer difference and models the activities of the components in the silicate and metallic phases using an expression of the Gibbs excess energy of mixing. Calculation of KD along a peridotite liquidus predicts a decrease in W siderophility at higher pressures that supports the qualitative behavior predicted by the WWO-IW buffer difference, and agrees with findings of others. Comparing the competing effects of temperature and pressure on W metal-silicate partitioning, our results indicate that pressure exerts a greater effect.

Shofner, G. A.↗
DOE OSTI2020

Materials Data on Fe7W6 by Materials Project

Fe7W6 is Frank-Kasper $\mu$ Phase structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are three inequivalent W sites. In the first W site, W is bonded in a 6-coordinate geometry to six equivalent W and six equivalent Fe atoms. There are three shorter (3.02 Å) and three longer (3.05 Å) W–W bond lengths. There are three shorter (2.71 Å) and three longer (2.76 Å) W–Fe bond lengths. In the second W site, W is bonded in a 12-coordinate geometry to four W and twelve Fe atoms. There are one shorter (2.67 Å) and three longer (2.86 Å) W–W bond lengths. There are a spread of W–Fe bond distances ranging from 2.72–2.86 Å. In the third W site, W is bonded in a 6-coordinate geometry to eight W and six equivalent Fe atoms. The W–W bond length is 2.56 Å. All W–Fe bond lengths are 2.62 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded to six equivalent W and six equivalent Fe atoms to form FeFe6W6 cuboctahedra that share corners with twelve equivalent FeFe5W7 cuboctahedra, edges with six equivalent FeFe6W6 cuboctahedra, and faces with eighteen equivalent FeFe5W7 cuboctahedra. All Fe–Fe bond lengths are 2.41 Å. In the second Fe site, Fe is bonded to seven W and five Fe atoms to form FeFe5W7 cuboctahedra that share corners with fifteen FeFe6W6 cuboctahedra, edges with five equivalent FeFe5W7 cuboctahedra, and faces with thirteen FeFe6W6 cuboctahedra. There are two shorter (2.36 Å) and two longer (2.40 Å) Fe–Fe bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe2W by Materials Project

Fe2W is Hexagonal Laves structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. W is bonded in a 12-coordinate geometry to four equivalent W and twelve Fe atoms. There are one shorter (2.83 Å) and three longer (2.91 Å) W–W bond lengths. There are a spread of W–Fe bond distances ranging from 2.73–2.81 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded to six equivalent W and six equivalent Fe atoms to form a mixture of face, edge, and corner-sharing FeFe6W6 cuboctahedra. All Fe–Fe bond lengths are 2.39 Å. In the second Fe site, Fe is bonded to six equivalent W and six Fe atoms to form a mixture of face, edge, and corner-sharing FeFe6W6 cuboctahedra. There are two shorter (2.29 Å) and two longer (2.39 Å) Fe–Fe bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe74W13 by Materials Project

W13Fe74 is alpha-derived structured and crystallizes in the orthorhombic Fmm2 space group. The structure is three-dimensional. there are six inequivalent W sites. In the first W site, W is bonded in a 3-coordinate geometry to sixteen Fe atoms. There are a spread of W–Fe bond distances ranging from 2.51–3.00 Å. In the second W site, W is bonded in a 3-coordinate geometry to one W and fifteen Fe atoms. The W–W bond length is 2.86 Å. There are a spread of W–Fe bond distances ranging from 2.51–2.98 Å. In the third W site, W is bonded in a 3-coordinate geometry to sixteen Fe atoms. There are a spread of W–Fe bond distances ranging from 2.52–2.99 Å. In the fourth W site, W is bonded in a 3-coordinate geometry to one W and fifteen Fe atoms. The W–W bond length is 2.86 Å. There are a spread of W–Fe bond distances ranging from 2.51–2.98 Å. In the fifth W site, W is bonded in a 3-coordinate geometry to sixteen Fe atoms. There are a spread of W–Fe bond distances ranging from 2.52–3.00 Å. In the sixth W site, W is bonded in a 12-coordinate geometry to four W and twelve Fe atoms. There are two shorter (2.76 Å) and ten longer (2.77 Å) W–Fe bond lengths. There are twenty-three inequivalent Fe sites. In the first Fe site, Fe is bonded to three W and nine Fe atoms to form distorted FeFe9W3 cuboctahedra that share corners with six FeFe9W3 cuboctahedra, a cornercorner with one FeFe12W4 tetrahedra, edges with eight FeFe9W3 cuboctahedra, faces with eleven FeFe9W3 cuboctahedra, and a faceface with one FeFe12W4 tetrahedra. There are a spread of Fe–Fe bond distances ranging from 2.33–2.77 Å. In the second Fe site, Fe is bonded to four W and eight Fe atoms to form distorted FeFe8W4 cuboctahedra that share corners with six FeFe9W3 cuboctahedra, edges with eight FeFe8W4 cuboctahedra, and faces with eleven FeFe8W4 cuboctahedra. There are a spread of Fe–Fe bond distances ranging from 2.32–2.60 Å. In the third Fe site, Fe is bonded to three W and nine Fe atoms to form distorted FeFe9W3 cuboctahedra that share corners with six FeFe9W3 cuboctahedra, a cornercorner with one FeFe12W4 tetrahedra, edges with eight FeFe9W3 cuboctahedra, faces with eleven FeFe9W3 cuboctahedra, and a faceface with one FeFe12W4 tetrahedra. There are a spread of Fe–Fe bond distances ranging from 2.33–2.76 Å. In the fourth Fe site, Fe is bonded to four W and eight Fe atoms to form a mixture of distorted corner, edge, and face-sharing FeFe8W4 cuboctahedra. There are a spread of Fe–Fe bond distances ranging from 2.33–2.62 Å. In the fifth Fe site, Fe is bonded to three W and nine Fe atoms to form distorted FeFe9W3 cuboctahedra that share corners with six FeFe9W3 cuboctahedra, a cornercorner with one FeFe12W4 tetrahedra, edges with eight FeFe8W4 cuboctahedra, faces with eleven FeFe9W3 cuboctahedra, and a faceface with one FeFe12W4 tetrahedra. There are a spread of Fe–Fe bond distances ranging from 2.33–2.76 Å. In the sixth Fe site, Fe is bonded to three W and nine Fe atoms to form distorted FeFe9W3 cuboctahedra that share corners with six equivalent FeFe9W3 cuboctahedra, a cornercorner with one FeFe12W4 tetrahedra, edges with eight FeFe9W3 cuboctahedra, faces with eleven FeFe9W3 cuboctahedra, and a faceface with one FeFe12W4 tetrahedra. There are a spread of Fe–Fe bond distances ranging from 2.32–2.76 Å. In the seventh Fe site, Fe is bonded to three W and nine Fe atoms to form distorted FeFe9W3 cuboctahedra that share corners with six FeFe9W3 cuboctahedra, edges with eight FeFe9W3 cuboctahedra, faces with eleven FeFe9W3 cuboctahedra, and a faceface with one FeFe12W4 tetrahedra. There are a spread of Fe–Fe bond distances ranging from 2.36–2.77 Å. In the eighth Fe site, Fe is bonded to four W and eight Fe atoms to form distorted FeFe8W4 cuboctahedra that share corners with six FeFe9W3 cuboctahedra, a cornercorner with one FeFe12W4 tetrahedra, edges with eight FeFe8W4 cuboctahedra, and faces with eleven FeFe8W4 cuboctahedra. There are a spread of Fe–Fe bond distances ranging from 2.33–2.62 Å. In the ninth Fe site, Fe is bonded to three W and nine Fe atoms to form distorted FeFe9W3 cuboctahedra that share corners with six FeFe9W3 cuboctahedra, a cornercorner with one FeFe12W4 tetrahedra, edges with eight FeFe9W3 cuboctahedra, faces with eleven FeFe9W3 cuboctahedra, and a faceface with one FeFe12W4 tetrahedra. There are a spread of Fe–Fe bond distances ranging from 2.35–2.76 Å. In the tenth Fe site, Fe is bonded to three W and nine Fe atoms to form distorted FeFe9W3 cuboctahedra that share corners with six FeFe9W3 cuboctahedra, edges with eight FeFe9W3 cuboctahedra, faces with eleven FeFe9W3 cuboctahedra, and a faceface with one FeFe12W4 tetrahedra. There are a spread of Fe–Fe bond distances ranging from 2.35–2.77 Å. In the eleventh Fe site, Fe is bonded to four W and eight Fe atoms to form distorted FeFe8W4 cuboctahedra that share corners with six FeFe8W4 cuboctahedra, a cornercorner with one FeFe12W4 tetrahedra, edges with eight FeFe9W3 cuboctahedra, and faces with eleven FeFe9W3 cuboctahedra. There are a spread of Fe–Fe bond distances ranging from 2.35–2.62 Å. In the twelfth Fe site, Fe is bonded to four W and twelve Fe atoms to form a mixture of distorted corner and face-sharing FeFe12W4 tetrahedra. In the thirteenth Fe site, Fe is bonded in a 1-coordinate geometry to two equivalent W and eleven Fe atoms. There are a spread of Fe–Fe bond distances ranging from 2.55–2.68 Å. In the fourteenth Fe site, Fe is bonded in a 1-coordinate geometry to two equivalent W and eleven Fe atoms. There are a spread of Fe–Fe bond distances ranging from 2.53–2.68 Å. In the fifteenth Fe site, Fe is bonded in a 1-coordinate geometry to two W and eleven Fe atoms. There are a spread of Fe–Fe bond distances ranging from 2.55–2.68 Å. In the sixteenth Fe site, Fe is bonded in a 1-coordinate geometry to two W and eleven Fe atoms. There are a spread of Fe–Fe bond distances ranging from 2.54–2.68 Å. In the seventeenth Fe site, Fe is bonded in a 1-coordinate geometry to two W and eleven Fe atoms. There are a spread of Fe–Fe bond distances ranging from 2.55–2.69 Å. In the eighteenth Fe site, Fe is bonded in a 1-coordinate geometry to two equivalent W and eleven Fe atoms. Both Fe–Fe bond lengths are 2.68 Å. In the nineteenth Fe site, Fe is bonded in a 1-coordinate geometry to two W and eleven Fe atoms. Both Fe–Fe bond lengths are 2.68 Å. In the twentieth Fe site, Fe is bonded in a 1-coordinate geometry to two W and eleven Fe atoms. Both Fe–Fe bond lengths are 2.69 Å. In the twenty-first Fe site, Fe is bonded in a 1-coordinate geometry to two W and eleven Fe atoms. The Fe–Fe bond length is 2.55 Å. In the twenty-second Fe site, Fe is bonded in a 1-coordinate geometry to two W and eleven Fe atoms. The Fe–Fe bond length is 2.55 Å. In the twenty-third Fe site, Fe is bonded in a 1-coordinate geometry to two W and eleven Fe atoms.

36 MATERIALS SCIENCE↗