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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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9 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Revealing the elusive role of water vapor in the oxidation behavior of a Mn-Si containing NiCr alloy at 950 °C

Detailed nanoscale characterizations revealed the formation of a considerably higher fraction of SiO 2 particles in the external Cr 2 O 3 layer on a NiCr alloy. In addition, atom probe tomography revealed substantially lower segregation of Mn at the Cr 2 O 3 grain boundaries in wet air compared to dry air exposures, where the intriguing formation of Mn-rich clusters was observed in the Cr 2 O 3 grains for the very first time. These findings provided additional evidence regarding the impact of distinct transport processes through the Cr 2 O 3 layer on the resulting oxidation rates and subsurface alloy compositional changes.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Understanding the effect of minor alloying elements on helium bubble formation in ferritic-martensitic steels

Ferritic-martensitic steels are promising structural materials for advanced nuclear reactors. To minimize long-term radioactivity, reduced-activation ferritic-martensitic steels have been developed by substituting high-activation elements like Ni and Mo with low-activation elements such as W. However, the impact of these alloying modifications on helium bubble formation, which plays a key role in material swelling, remains unclear. Here, in this study, we compared helium bubble formation in ferritic-martensitic steel T91 and reduced-activation ferritic-martensitic steel F82H. Both materials were irradiated with sequential 100 keV, 150 keV, and 200 keV helium ions to a dose of 0.5 dpa and a helium concentration of 9,000 appm at 500°C. The helium bubbles in F82H exhibited a larger average size and a lower density than those in T91, suggesting differences in minor alloying elements may influence the bubble growth. Here, to investigate the effects of these alloying elements, we characterized radiation-induced segregation near bubbles and grain boundaries. Prominent Ni-Mn-Si enriched clusters were found near bubbles in T91, while only Mn-Si enriched clusters were found near bubbles in F82H. In addition, the obvious Cr enrichment near grain boundaries was absent around bubbles in both steels. The different segregation trends among elements revealed the variations in element diffusion mechanisms and the different sink biases between bubbles and grain boundaries. Cr enrichment near grain boundaries is mostly driven by interstitial-mediated diffusion. However, since bubble growth relies on net vacancy flux, vacancy-mediated diffusion plays a dominant role in controlling element segregation near bubbles. Therefore, Cr enrichment was not found near bubbles. Because of preferential vacancy-drag diffusion for Ni, Si and Mn, these elements were enriched near bubbles. Due to the strong binding energies of vacancies with these solute atoms, the vacancy diffusivity can be reduced near these solutes. Therefore, the more prominent Ni-Si-Mn clustered near helium bubbles in T91 lead to stronger suppression of helium bubble growth compared to F82H.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn5Si3 by Materials Project

Mn5Si3 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent Mn+2.40+ sites. In the first Mn+2.40+ site, Mn+2.40+ is bonded to five equivalent Si4- atoms to form a mixture of distorted edge and corner-sharing MnSi5 trigonal bipyramids. There are a spread of Mn–Si bond distances ranging from 2.40–2.62 Å. In the second Mn+2.40+ site, Mn+2.40+ is bonded in a 6-coordinate geometry to two equivalent Mn+2.40+ and six equivalent Si4- atoms. Both Mn–Mn bond lengths are 2.40 Å. All Mn–Si bond lengths are 2.43 Å. Si4- is bonded in a 9-coordinate geometry to nine Mn+2.40+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MnSi by Materials Project

MnSi is alpha-derived structured and crystallizes in the cubic P2_13 space group. The structure is three-dimensional. Mn4+ is bonded in a 7-coordinate geometry to seven equivalent Si4- atoms. There are a spread of Mn–Si bond distances ranging from 2.28–2.53 Å. Si4- is bonded in a 7-coordinate geometry to seven equivalent Mn4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn3Si by Materials Project

Mn3Si is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. there are two inequivalent Mn sites. In the first Mn site, Mn is bonded in a distorted body-centered cubic geometry to four equivalent Mn and four equivalent Si atoms. All Mn–Mn bond lengths are 2.45 Å. All Mn–Si bond lengths are 2.45 Å. In the second Mn site, Mn is bonded in a 8-coordinate geometry to eight equivalent Mn and six equivalent Si atoms. All Mn–Si bond lengths are 2.83 Å. Si is bonded in a distorted body-centered cubic geometry to fourteen Mn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn4Si7 by Materials Project

Mn4Si7 crystallizes in the monoclinic P2 space group. The structure is three-dimensional. there are sixteen inequivalent Mn3+ sites. In the first Mn3+ site, Mn3+ is bonded in a 10-coordinate geometry to ten Si+1.71- atoms. There are a spread of Mn–Si bond distances ranging from 2.29–2.90 Å. In the second Mn3+ site, Mn3+ is bonded in a 8-coordinate geometry to eight Si+1.71- atoms. There are a spread of Mn–Si bond distances ranging from 2.30–2.56 Å. In the third Mn3+ site, Mn3+ is bonded in a 8-coordinate geometry to eight Si+1.71- atoms. There are a spread of Mn–Si bond distances ranging from 2.29–2.56 Å. In the fourth Mn3+ site, Mn3+ is bonded in a 8-coordinate geometry to eight Si+1.71- atoms. There are a spread of Mn–Si bond distances ranging from 2.32–2.50 Å. In the fifth Mn3+ site, Mn3+ is bonded in a 8-coordinate geometry to eight Si+1.71- atoms. There are a spread of Mn–Si bond distances ranging from 2.33–2.50 Å. In the sixth Mn3+ site, Mn3+ is bonded in a 8-coordinate geometry to eight Si+1.71- atoms. There are a spread of Mn–Si bond distances ranging from 2.29–2.56 Å. In the seventh Mn3+ site, Mn3+ is bonded in a 8-coordinate geometry to eight Si+1.71- atoms. There are a spread of Mn–Si bond distances ranging from 2.36–2.42 Å. In the eighth Mn3+ site, Mn3+ is bonded in a 8-coordinate geometry to eight Si+1.71- atoms. There are a spread of Mn–Si bond distances ranging from 2.32–2.50 Å. In the ninth Mn3+ site, Mn3+ is bonded in a 10-coordinate geometry to ten Si+1.71- atoms. There are a spread of Mn–Si bond distances ranging from 2.29–2.91 Å. In the tenth Mn3+ site, Mn3+ is bonded in a 8-coordinate geometry to eight Si+1.71- atoms. There are a spread of Mn–Si bond distances ranging from 2.32–2.50 Å. In the eleventh Mn3+ site, Mn3+ is bonded in a 8-coordinate geometry to eight Si+1.71- atoms. There are a spread of Mn–Si bond distances ranging from 2.36–2.42 Å. In the twelfth Mn3+ site, Mn3+ is bonded in a 8-coordinate geometry to eight Si+1.71- atoms. There are a spread of Mn–Si bond distances ranging from 2.36–2.42 Å. In the thirteenth Mn3+ site, Mn3+ is bonded in a 8-coordinate geometry to eight Si+1.71- atoms. There are a spread of Mn–Si bond distances ranging from 2.29–2.56 Å. In the fourteenth Mn3+ site, Mn3+ is bonded in a 8-coordinate geometry to eight Si+1.71- atoms. There are a spread of Mn–Si bond distances ranging from 2.37–2.42 Å. In the fifteenth Mn3+ site, Mn3+ is bonded in a 10-coordinate geometry to ten Si+1.71- atoms. There are a spread of Mn–Si bond distances ranging from 2.29–2.90 Å. In the sixteenth Mn3+ site, Mn3+ is bonded in a 10-coordinate geometry to ten Si+1.71- atoms. There are a spread of Mn–Si bond distances ranging from 2.29–2.90 Å. There are fourteen inequivalent Si+1.71- sites. In the first Si+1.71- site, Si+1.71- is bonded in a 4-coordinate geometry to five Mn3+ atoms. In the second Si+1.71- site, Si+1.71- is bonded in a 5-coordinate geometry to five Mn3+ atoms. In the third Si+1.71- site, Si+1.71- is bonded in a 4-coordinate geometry to five Mn3+ atoms. In the fourth Si+1.71- site, Si+1.71- is bonded in a 5-coordinate geometry to five Mn3+ atoms. In the fifth Si+1.71- site, Si+1.71- is bonded in a 4-coordinate geometry to five Mn3+ atoms. In the sixth Si+1.71- site, Si+1.71- is bonded in a 5-coordinate geometry to five Mn3+ atoms. In the seventh Si+1.71- site, Si+1.71- is bonded in a 5-coordinate geometry to five Mn3+ atoms. In the eighth Si+1.71- site, Si+1.71- is bonded in a 5-coordinate geometry to five Mn3+ atoms. In the ninth Si+1.71- site, Si+1.71- is bonded in a 5-coordinate geometry to five Mn3+ atoms. In the tenth Si+1.71- site, Si+1.71- is bonded in a 5-coordinate geometry to five Mn3+ atoms. In the eleventh Si+1.71- site, Si+1.71- is bonded in a 4-coordinate geometry to four Mn3+ atoms. In the twelfth Si+1.71- site, Si+1.71- is bonded in a 5-coordinate geometry to five Mn3+ atoms. In the thirteenth Si+1.71- site, Si+1.71- is bonded in a 4-coordinate geometry to five Mn3+ atoms. In the fourteenth Si+1.71- site, Si+1.71- is bonded in a 4-coordinate geometry to four Mn3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn5Si2 by Materials Project

Mn5Si2 is beta Plutonium-derived structured and crystallizes in the tetragonal P4_12_12 space group. The structure is three-dimensional. there are six inequivalent Mn sites. In the first Mn site, Mn is bonded in a 4-coordinate geometry to four Mn and four Si atoms. There are two shorter (2.47 Å) and two longer (2.76 Å) Mn–Mn bond lengths. There are two shorter (2.38 Å) and two longer (2.42 Å) Mn–Si bond lengths. In the second Mn site, Mn is bonded in a 10-coordinate geometry to ten Mn and four Si atoms. There are a spread of Mn–Mn bond distances ranging from 2.52–2.76 Å. There are two shorter (2.50 Å) and two longer (2.61 Å) Mn–Si bond lengths. In the third Mn site, Mn is bonded in a 4-coordinate geometry to four Mn and five Si atoms. There are a spread of Mn–Mn bond distances ranging from 2.54–2.73 Å. There are a spread of Mn–Si bond distances ranging from 2.52–2.84 Å. In the fourth Mn site, Mn is bonded in a 12-coordinate geometry to nine Mn and three Si atoms. There are a spread of Mn–Mn bond distances ranging from 2.23–2.61 Å. There are a spread of Mn–Si bond distances ranging from 2.29–2.41 Å. In the fifth Mn site, Mn is bonded in a 4-coordinate geometry to two Mn and five Si atoms. There are a spread of Mn–Si bond distances ranging from 2.34–2.70 Å. In the sixth Mn site, Mn is bonded in a 4-coordinate geometry to one Mn and four Si atoms. There are a spread of Mn–Si bond distances ranging from 2.33–2.61 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded in a 10-coordinate geometry to ten Mn atoms. In the second Si site, Si is bonded in a 12-coordinate geometry to eleven Mn and one Si atom. The Si–Si bond length is 2.61 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn3Si by Materials Project

Mn3Si crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are two inequivalent Mn sites. In the first Mn site, Mn is bonded in a 8-coordinate geometry to four equivalent Mn and four equivalent Si atoms. All Mn–Mn bond lengths are 2.44 Å. All Mn–Si bond lengths are 2.42 Å. In the second Mn site, Mn is bonded in a 8-coordinate geometry to twelve Mn and two equivalent Si atoms. All Mn–Mn bond lengths are 2.79 Å. Both Mn–Si bond lengths are 2.84 Å. Si is bonded in a body-centered cubic geometry to ten Mn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn5Si2 by Materials Project

Mn5Si2 is beta Plutonium-derived structured and crystallizes in the tetragonal P4_12_12 space group. The structure is three-dimensional. there are six inequivalent Mn sites. In the first Mn site, Mn is bonded in a 5-coordinate geometry to one Mn and five Si atoms. The Mn–Mn bond length is 2.64 Å. There are a spread of Mn–Si bond distances ranging from 2.43–2.64 Å. In the second Mn site, Mn is bonded in a 12-coordinate geometry to two equivalent Mn and two equivalent Si atoms. There are one shorter (2.30 Å) and one longer (2.45 Å) Mn–Mn bond lengths. There are one shorter (2.30 Å) and one longer (2.37 Å) Mn–Si bond lengths. In the third Mn site, Mn is bonded in a 4-coordinate geometry to three equivalent Mn and four Si atoms. There are one shorter (2.65 Å) and two longer (2.66 Å) Mn–Mn bond lengths. There are a spread of Mn–Si bond distances ranging from 2.54–2.65 Å. In the fourth Mn site, Mn is bonded in a 2-coordinate geometry to two equivalent Mn and two equivalent Si atoms. Both Mn–Mn bond lengths are 2.42 Å. Both Mn–Si bond lengths are 2.34 Å. In the fifth Mn site, Mn is bonded in a 12-coordinate geometry to four equivalent Mn and two equivalent Si atoms. There are two shorter (2.54 Å) and two longer (2.62 Å) Mn–Mn bond lengths. Both Mn–Si bond lengths are 2.49 Å. In the sixth Mn site, Mn is bonded in a 12-coordinate geometry to ten Mn and two Si atoms. The Mn–Mn bond length is 2.24 Å. There are one shorter (2.30 Å) and one longer (2.35 Å) Mn–Si bond lengths. There are two inequivalent Si sites. In the first Si site, Si is bonded in a 11-coordinate geometry to seven Mn atoms. In the second Si site, Si is bonded in a 8-coordinate geometry to eight Mn atoms.

36 MATERIALS SCIENCE↗