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All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Role of carbon and hydrogen in limiting n -type doping of monoclinic ( Al x Ga 1 – x ) 2 O 3

In this study, we use hybrid density functional calculations to assess n -type doping in monoclinic ( Al x Ga 1 – x ) 2 O 3 alloys. We focus on silicon, the most promising donor dopant, and study the structural properties, formation energies, and charge-state transition levels of its various configurations. We also explore the impact of carbon and hydrogen, which are common impurities in metal-organic chemical vapor deposition (MOCVD). In Ga 2 O 3 , Si Ga is an effective shallow donor, but in Al 2 O 3 Si Al acts as a DX center with a ( + / – ) transition level in the band gap. Interstitial hydrogen acts as a shallow donor in Ga 2 O 3 but behaves as a compensating acceptor in n -type Al 2 O 3 . Interpolation indicates that Si is an effective donor in ( Al x Ga 1 – x ) 2 O 3 up to 70% Al, but it can be compensated by hydrogen already at 1% Al. We also assess the diffusivity of hydrogen and study complex formation. Si cation – H complexes have relatively low binding energies. Substitutional carbon on a cation site acts as a shallow donor in Ga 2 O 3 , but can be stable in a negative charge state in ( Al x Ga 1 – x ) 2 O 3 when x > 5 % . Substitutional carbon on an oxygen site ( C O ) always acts as an acceptor in n -type ( Al x Ga 1 – x ) 2 O 3 , but will incorporate only under relatively oxygen-poor conditions. C O – H complexes can actually incorporate more easily, explaining observations of carbon-related compensation in Ga 2 O 3 grown by MOCVD. We also investigate C cation – H complexes, finding they have high binding energies and act as compensating acceptors when x > 56 % ; otherwise the hydrogen just passivates the unintentional carbon donors. C-H complex formation explains why MOCVD-grown Ga 2 O 3 can exhibit record-low free-carrier concentrations, in spite of the unavoidable incorporation of carbon. Our study highlights that, while Si is in principle a suitable shallow donor in ( Al x Ga 1 – x ) 2 O 3 alloys up to high Al compositions, control of unintentional impurities is essential to avoid compensation.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Tritium Diffusion in Fe-Al Aluminide Coating Bulk Phases

The theoretical investigations of interstitial tritium diffusion pathways in various Al-rich (>60% at. Al) iron aluminide coating phases found that in FeNiAl 5 tritium prefers to diffuse in between layers, while in Fe 4 Al 13 , tritium prefers to diffuse across layers. In the case of Fe 2 Al x phases, the simulations show that the variable Al content in the channels affects the diffusion behavior of tritium in the channels. For 100% of vacancy, tritium prefers to diffuse at the center of the channel, while for 0% Al vacancy, tritium prefers to diffuse along the channel’s wall. In the case where 50% Al vacancy are present in the channels, tritium can diffuse in a mixed way, with positions oscillating between the channel’s center and wall. However, the large energy barrier involved in this case suggests that tritium diffusion could be correlated with Al diffusion in the channels. While we found that at 600 K interstitial tritium diffuses faster in Fe 2 Al x phases (D Τ ≤10 -11 m 2 .s -1 ), then in Fe 4 Al 13 (D Τ ≈10 -12 m 2 .s -1 ), and finally in FeNiAl 5 (D Τ ≈10 -13 m 2 .s -1 ), we also find that interstitial tritium generally diffuses faster in Fe-Al coating phases than in γ-LiAlO 2 pellets (D Τ ≈10 -14 m 2 .s -1 ).

36 MATERIALS SCIENCE↗
DOE OSTI2022

First-Principles Study of Tritium Trapping by Point Defects in Fe-Al Aluminide Coating Phases

Density functional theory simulations have been carried out to investigate the potential for tritium trapping by metal vacancies in five different Fe-Al aluminide coating phases. It was found that tritiation of Fe and Ni vacancies is generally less favorable than the tritiation of Al vacancies. However, for the first tritiation, a trend in the defect formation energy can be obtained such that metal defects in the Fe 2 Al x family of materials (i.e., Fe 2 Al 4 , Fe 2 Al 5 , and Fe 2 Al 6 ) trap tritium species more favorably than metal vacancies in Fe 4 Al 13 and FeNiAl 5 . Further investigations using ab initio thermodynamics calculations confirmed that trend for a range of tritium partial pressure at a temperature of 700 K. Especially, it was shown that the energy difference between tritiated and non-tritiated metal vacancies is smaller and more favorable for the Fe 2 Al x family, followed by Fe 4 Al 13 , and FeNiAl 5 . While this study shows that tritium interacts differently in the various Fe-Al aluminide phases, it also suggests that tritium trapping and retention could be more efficient if metal defects are present in some Fe-Al phases.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al(HO)3 by Materials Project

Al(OH)3 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of one Al(OH)3 sheet oriented in the (0, 0, 1) direction. there are eight inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.87–2.12 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.86–1.99 Å. In the third Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.84–2.08 Å. In the fourth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.86–2.01 Å. In the fifth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.90–1.92 Å. In the sixth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.89–1.97 Å. In the seventh Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.88–1.96 Å. In the eighth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.84–2.02 Å. There are twenty-four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.72 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.01 Å. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourteenth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.05 Å) and one longer (1.52 Å) H–O bond length. In the fifteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the sixteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the seventeenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the eighteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the nineteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the twentieth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the twenty-first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the twenty-second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the twenty-third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the twenty-fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two Al3+ and one H1+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the eighth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the ninth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the tenth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the eleventh O2- site, O2- is bonded in a 1-coordinate geometry to two Al3+ and one H1+ atom. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to two Al3+ and two H1+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted water-like geometry to two Al3+ and two H1+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fifteenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the sixteenth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the seventeenth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the eighteenth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the nineteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one H1+ atom. In the twentieth O2- site, O2- is bonded in a 2-coordinate geometry to two Al3+ and one H1+ atom. In the twenty-first O2- site, O2- is bonded in a 1-coordinate geometry to two Al3+ and one H1+ atom. In the twenty-second O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the twenty-third O2- site, O2- is bonded in a 1-coordinate geometry to two Al3+ and one H1+ atom. In the twenty-fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al(HO)3 by Materials Project

Al(OH)3 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of one Al(OH)3 sheet oriented in the (0, 0, 1) direction. there are eight inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.84–2.06 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.80–2.07 Å. In the third Al3+ site, Al3+ is bonded to six O2- atoms to form distorted edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.80–2.23 Å. In the fourth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.87–1.97 Å. In the fifth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.83–2.14 Å. In the sixth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.81–2.18 Å. In the seventh Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.83–2.07 Å. In the eighth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.86–2.08 Å. There are twenty-four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.06 Å) and one longer (1.51 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.06 Å) and one longer (1.50 Å) H–O bond length. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.01 Å. In the eighth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.05 Å) and one longer (1.52 Å) H–O bond length. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the eleventh H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.06 Å) and one longer (1.45 Å) H–O bond length. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the thirteenth H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fifteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the sixteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the seventeenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the eighteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the nineteenth H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the twentieth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the twenty-first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the twenty-second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the twenty-third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the twenty-fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two Al3+ and one H1+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two Al3+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to two Al3+ and one H1+ atom. In the seventh O2- site, O2- is bonded in a distorted water-like geometry to two Al3+ and two H1+ atoms. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to two Al3+ and one H1+ atom. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to two Al3+ and one H1+ atom. In the tenth O2- site, O2- is bonded in a distorted water-like geometry to two Al3+ and two H1+ atoms. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to two Al3+ and one H1+ atom. In the twelfth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the thirteenth O2- site, O2- is bonded in a 1-coordinate geometry to two Al3+ and one H1+ atom. In the fourteenth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fifteenth O2- site, O2- is bonded in a 1-coordinate geometry to two Al3+ and two H1+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the seventeenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one H1+ atom. In the eighteenth O2- site, O2- is bonded in a trigonal planar geometry to two Al3+ and one H1+ atom. In the nineteenth O2- site, O2- is bonded in a trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the twentieth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the twenty-first O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the twenty-second O2- site, O2- is bonded in a 1-coordinate geometry to two Al3+ and two H1+ atoms. In the twenty-third O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the twenty-fourth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al(HO)3 by Materials Project

Al(OH)3 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of one Al(OH)3 sheet oriented in the (0, 0, 1) direction. there are eight inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.91–1.93 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.88–2.01 Å. In the third Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.86–2.07 Å. In the fourth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.85–2.03 Å. In the fifth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.87–1.95 Å. In the sixth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.89–1.97 Å. In the seventh Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.83–2.04 Å. In the eighth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.87–2.12 Å. There are twenty-four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fifteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the sixteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the seventeenth H1+ site, H1+ is bonded in a single-bond geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.71 Å) H–O bond length. In the eighteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the nineteenth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.05 Å) and one longer (1.53 Å) H–O bond length. In the twentieth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the twenty-first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the twenty-second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the twenty-third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the twenty-fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the eighth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the ninth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to two Al3+ and two H1+ atoms. In the eleventh O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the twelfth O2- site, O2- is bonded in a 2-coordinate geometry to two Al3+ and one H1+ atom. In the thirteenth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fourteenth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fifteenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the sixteenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the seventeenth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the eighteenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the nineteenth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the twentieth O2- site, O2- is bonded in a distorted water-like geometry to two Al3+ and two H1+ atoms. In the twenty-first O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the twenty-second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the twenty-third O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the twenty-fourth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Localized corrosion at nm-scale hardening precipitates in Al-Cu-Li alloys

The localized corrosion of Li-containing nm hardening precipitates in the 3rd generation of Al-Cu-Li alloys was investigated based on a quasi in situ approach by sequentially exposing the material to NaCl solution and characterizing the structural, chemical, and electrochemical evolution at atomic scale using electron microscopy, spectroscopy, 3D tomography, electrochemical measurements, and DFT calculations. Localized corrosion of Al 7.5 Cu 4 Li (TB phase) initiated along {001} family of planes through the dealloying of Al and Li due to a low surface work function. Cu was enriched along the Cu (110) // T B (011) // Al (100) orientations on and around corroded T B precipitates. No strong galvanic interactions were observed at the T B and Al matrix interface due to the formation of a Li-C-O rich passivation layer during electrolyte exposure. Similarities and differences between T B and other common Al-Cu-Li precipitates (Al 2 CuLi, Al 6 CuLi 3 , and Al 3 Li) with respect to corrosion are discussed. Overall, the reported corrosion mechanism can assist in the assessment of the localized corrosion susceptibility of precipitation-hardened Al alloys and assist in the design of new alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Control of High-Temperature Static and Transient Thermomechanical Behavior of SiMo Ductile Iron by Al Alloying

Abstract Silicon and molybdenum ( SiMo ) ductile iron is commonly used for exhaust manifolds because these components experience thermal cycling in oxidizing environment, which requires resistance to fatigue during transient thermomechanical loads. Previous studies have demonstrated that alloying elements, such as Al , to SiMo ductile iron reduces the amount of surface degradation during static high-temperature exposure. However, deterioration of sphericity of the graphite nodules and a decrease in ductility could affect the tendency of cracking during thermal cycling. In this article, the effect of Al alloying on static and transient thermomechanical behavior of SiMo ductile iron was investigated to optimize the amount of Al alloying. A thermodynamic approach was used to confirm the effect of the Al alloying on the phase transformations in two SiMo cast irons, alloyed by 1.8% Al and 3% Al . These two alloys were cast in a laboratory along with the baseline SiMo ductile iron. Several experimental methods were used to evaluate the dimensional stability, physical properties, static oxidation, and failure resistance during constrained thermal cycling testing to compare their high-temperature capability. Experimental results verified that Al alloying increases the temperature range and decreases volume change during eutectoid transformation, which together with enhancement of oxidation protection improved the dimensional stability. Thermocycling tests showed that the number of cycles to failure depends on the amount of Al alloying and the applied high-temperature exposure during each cycle. SEM/EDX, high-resolution TEM and µCT analysis were used to verify the mechanism resulting from the Al alloying protection. It was shown that an optimal level of Al alloying for balancing oxidation and thermal cracking resistance depends on thermomechanical conditions of application.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Effect of Sn microalloying on the nucleation of L1 2 Al 3 Zr precipitates in a dilute aluminum-zirconium alloy

While L1 2 -Al 3 Zr nanoprecipitates provide a balance between strengthening and good electrical conductivity, the precipitation of L1 2 -Al 3 Zr in aluminum requires aggressive heat treatments. An improved age-hardening response was observed during isochronal aging of an Al-0.24Zr (wt%) alloy when microalloyed with Sn. A new mechanism termed Low melting point Element-Assisted Nucleation (LEAN) is proposed to explain the lower temperature nucleation of L1 2 -Al 3 Zr precipitates observed in this alloy based on the addition of a low melting point element, such as Sn. Characterization verified the first-principles density functional theory prediction that Zr and Sn atoms cluster during homogenization owing to the favorable binding energy of Zr-Sn-vacancy triplets. Direct microstructural observations revealed these clusters form Sn nanoprecipitates that assist the nucleation of L1 2 -Al 3 Zr at 200°C, where L1 2 -Al 3 Zr precipitation is not expected due to the low diffusivity of Zr atoms in Al. At higher temperatures (≳350°C), the acceleration of L1 2 -Al 3 Zr precipitation is driven by faster Zr diffusion in Al with Sn microalloying and the nuclei formed via the LEAN mechanism. In conclusion, this combination of mechanisms explains the improvement in age hardening through L1 2 -Al 3 Zr precipitation with Sn microalloying.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Microstructural refinement of an Al-Ce-Mg alloy via Shear Assisted Processing and Extrusion

Al-Ce alloys have attracted recent interest because of their high thermal stability due to the low solubility of Ce in the Al matrix. The Al 11 Ce 3 eutectic phase gives excellent strain hardening behavior and moderate high-temperature strength in the as-cast state. However, its strengthening effect is limited by its coarse as-cast structure. Therefore, alternative manufacturing methods such as additive manufacturing or equal channel angular pressing have been applied to refine the Al 11 Ce 3 phase to good effect. However, these techniques are both expensive and time-consuming. Therefore, this study aims to use Shear Assisted Processing and Extrusion (ShAPE), an emerging solid phase processing technique that is more easily scalable than the previously mentioned methods. ShAPE can produce useful cross-sections of an Al-8Ce-4Mg alloy while refining the Al 11 Ce 3 phase to produce a higher strength material. It was found that a low temperature ShAPE process can improve the room temperature yield strength by ~60 % compared to a binary Al-4Mg alloy. Additionally, the high-temperature yield strength of the Al-Ce alloys increased by 20%, with a simultaneous 15% improvement in ductility compared to the binary Al-Mg alloy. Finally, these results highlight the potential for ShAPE as a processing technique for Al-Ce alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2020

27 AlNMR chemical shift of Al(OH)$^{-}_{4}$ calculated from first principles: Assessment of error cancellation in chemically distinct reference and target systems

Predicting accurate nuclear magnetic resonance chemical shieldings relies upon cancellation of different types of errors between the theoretically calculated shielding constant of the analyte of interest and the reference. Often, the intrinsic error in computed shieldings due to basis sets, approximations in the Hamiltonian, description of the wave function, and dynamic effects is nearly identical between the analyte and reference, yet if the electronic structure or sensitivity to local environment differs dramatically, this cannot be taken for granted. Detailed prior work has examined the octahedral trivalent cation Al(H 2 O)$^{3+}_{6}$, accounting for ab initio intrinsic errors. However, the use of this species as a reference for the chemically distinct tetrahedral anion Al(OH)$^{-}_{4}$ requires an understanding of how these errors cancel, in order to define the limits of accurately predicting 27 Al chemical shielding in Al(OH)$^{-}_{4}$. In this work, we estimate the absolute shielding of the 27 Al nucleus in Al(OH)$^{-}_{4}$ at the coupled cluster level (515.1± 5.3 ppm). Shielding sensitivity to the choice of method approximation and atomic basis sets used has been evaluated. Solvent and thermal effects are assessed through ensemble averaging techniques using ab-initio molecular dynamics. The contribution of each type of intrinsic error is assessed for the Al(H 2 O)$^{3+}_{6}$ and Al(OH)$^{-}_{4}$ ions, revealing significant differences that fundamentally hamper the ability to accurately calculate the 27 Al chemical shift of Al(OH)$^{-}_{4}$ from first principles.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Secondary corundum‐bearing assemblages in Allende Ca,Al‐rich inclusions: Mineralogy, petrology, oxygen, and aluminum–magnesium isotope systematics

Here, we report on the mineralogy, petrology, oxygen, and aluminum–magnesium isotopic systematics of the secondary corundum-bearing assemblages in type B CAIs 3529Z and 3529G and fluffy type A (FTA) CAI ALH-2 from Allende (CV > 3.6). In 3529Z and 3529G, 2–5 μm-sized euhedral-to-subhedral corundum grains associate with secondary alumoåkermanite [(Ca,Na) 2 AlSi 2 O 7 ], grossular, spinel, grossite, celsian, kushiroite, and wadalite. In ALH-2, 2–5 μm-sized euhedral-to-subhedral corundum grains associate with secondary grossular, nepheline, spinel, and kushiroite. In 3529Z and 3529G, corundum and associated secondary grossite, spinel, alumoåkermanite, grossular, and kushiroite have similar 16 O-poor compositions (Δ 17 O = −2.2 ± 1.5‰); primary spinel is 16 O-rich (Δ 17 O ~ −23‰); Al,Ti-diopside shows a range of Δ 17 O (from ~ −24‰ to ~ −15‰); anorthite and melilite are 16 O-depleted to various degrees (−6.5‰ ≤ Δ 17 O ≤ −4.5‰ and Δ 17 O = −2.7 ± 0.8‰, respectively). In ALH-2, corundum shows a range of Δ 17 O, from ~ −9‰ to ~ −1‰; primary hibonite and spinel are 16 O-rich (Δ 17 O ~ −23‰); melilite and perovskite are 16 O-poor (Δ 17 O = −2.6 ± 1.5‰ and −3.1 ± 1.3‰, respectively). On the Al-Mg isotope diagram ( 26 Mg* versus 27 Al/ 24 Mg), primary Al,Ti-diopside, hibonite, melilite, and spinel in the Allende CAIs studied along the canonical isochron with inferred initial 26 Al/ 27 Al ratio [( 26 Al/ 27 Al) 0 ] of ~5 × 10 −5 . All secondary minerals have resolved excesses of 26 Mg*: alumoåkermanite, corundum, and grossite plot below the canonical isochron, whereas most spinel analyses plot above it. An internal isochron defined by the coexisting secondary corundum and alumoåkermanite in 3529Z has ( 26 Al/ 27 Al) 0 = (7.5 ± 2.6) × 10 −7 . We conclude that the corundum-bearing assemblages in Allende CAIs resulted from metasomatic alteration of primary melilite and anorthite, ~4–5 Ma after their crystallization. Metasomatic alteration of CAIs in the Allende parent asteroid by an aqueous fluid having Δ 17 O of ~ −3 ± 2‰ modified the O-isotope composition of their primary melilite, anorthite, and Ti-rich pyroxene; O-isotope compositions of primary hibonite, spinel, and low-Ti pyroxene escaped this modification.

Geosciences↗
NASA NTRS2003

Characterization of Al-Cu-Mg-Ag Alloy RX226-T8 Plate

Aluminum-copper-magnesium-silver (Al-Cu-Mg-Ag) alloys that were developed for thermal stability also offer attractive ambient temperature strength-toughness combinations, and therefore, can be considered for a broad range of airframe structural applications. The current study evaluated Al-Cu-Mg-Ag alloy RX226-T8 in plate gages and compared performance with sheet gage alloys of similar composition. Uniaxial tensile properties, plane strain initiation fracture toughness, and plane stress tearing resistance of RX226-T8 were examined at ambient temperature as a function of orientation and thickness location in the plate. Properties were measured near the surface and at the mid-plane of the plate. Tensile strengths were essentially isotropic, with variations in yield and ultimate tensile strengths of less than 2% as a function of orientation and through-thickness location. However, ductility varied by more than 15% with orientation. Fracture toughness was generally higher at the mid-plane and greater for the L-T orientation, although the differences were small near the surface of the plate. Metallurgical analysis indicated that the microstructure was primarily recrystallized with weak texture and was uniform through the plate with the exception of a fine-grained layer near the surface of the plate. Scanning electron microscope analysis revealed Al-Cu-Mg second phase particles which varied in composition and were primarily located on grain boundaries parallel to the rolling direction. Fractography of toughness specimens for both plate locations and orientations revealed that fracture occurred predominantly by transgranular microvoid coalescence. Introduction High-strength, low-density Al-Cu-Mg-Ag alloys were initially developed to replace conventional 2000 (Al-Cu-Mg) and 7000 (Al-Zn-Cu-Mg) series aluminum alloys for aircraft structural applications [1]. During the High Speed Civil Transport (HSCT) program, improvements in thermal stability were demonstrated for candidate aircraft wing and fuselage skin materials through the addition of silver to Al-Cu-Mg alloys based on Al 2519 chemistry [2]. Thermal stability of the resulting Al-Cu-Mg-Ag alloys, C415-T8 and C416-T8, was due to co-precipitation of the thermally stable . (AlCu) and ' (Al2Cu) strengthening phases [1-4]. The strength and toughness behavior was investigated for these alloys produced as 0.090-inch thick rolled sheet in the T8 condition and after various thermal exposures. The mechanical properties were shown to be competitive with conventional aircraft alloys, 2519-T8 and 2618-T8 [2]. During the Integral Airframe Structure (IAS) program, advanced aluminum alloys were examined for use in an integrally stiffened airframe structure where the skin and stiffeners would be machined from plate and extruded frames would be mechanically attached (see Figure 1) [5]. Advantages of integrally stiffened structure include reduced part count, and reduced assembly times compared to conventional built-up airframe structure. The near-surface properties of a thick plate are of significance for a machined integrally stiffened airframe structure since this represents the skin location. Properties measured at the mid-plane of the plate are more representative of the stiffener web. RX226 was developed to exploit strength-toughness improvements and thermal stability benefits of Al-Cu-Mg-Ag alloys in plate gages. This study evaluated the microstructure and properties of three gages of plate produced in the T8 condition.

Lach, Cynthia L.↗
DOE OSTI2020

Materials Data on Al(HO)3 by Materials Project

Al(OH)3 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of one Al4H11O12 sheet oriented in the (0, 0, 1) direction and one Al4H13O12 sheet oriented in the (0, 0, 1) direction. In the Al4H11O12 sheet, there are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.89–1.95 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.87–2.00 Å. In the third Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.87–2.09 Å. In the fourth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.89–1.97 Å. There are eleven inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one H1+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the seventh O2- site, O2- is bonded in a water-like geometry to two Al3+ atoms. In the eighth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the ninth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the tenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the eleventh O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the twelfth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the Al4H13O12 sheet, there are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share a cornercorner with one AlO5 trigonal bipyramid and edges with two equivalent AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.87–2.06 Å. In the second Al3+ site, Al3+ is bonded to five O2- atoms to form a mixture of distorted edge and corner-sharing AlO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 63°. There are a spread of Al–O bond distances ranging from 1.83–1.89 Å. In the third Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share an edgeedge with one AlO6 octahedra and edges with two equivalent AlO5 trigonal bipyramids. There are a spread of Al–O bond distances ranging from 1.86–1.95 Å. In the fourth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.89–1.97 Å. There are thirteen inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.01 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the second O2- site, O2- is bonded in a distorted water-like geometry to one Al3+ and two H1+ atoms. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two Al3+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the eighth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to two Al3+ and one H1+ atom. In the eleventh O2- site, O2- is bonded in a 1-coordinate geometry to two Al3+ and one H1+ atom. In the twelfth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al(HO)3 by Materials Project

Al(OH)3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form distorted edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.81–2.17 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form distorted edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.80–2.21 Å. In the third Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.88–1.97 Å. In the fourth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.86–1.98 Å. In the fifth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.83–2.07 Å. In the sixth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.84–2.16 Å. In the seventh Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.87–2.00 Å. In the eighth Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.89–1.94 Å. There are twenty-four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fifteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the sixteenth H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.03 Å) and one longer (1.58 Å) H–O bond length. In the seventeenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the eighteenth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.06 Å) and one longer (1.48 Å) H–O bond length. In the nineteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.01 Å. In the twentieth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.04 Å) and one longer (1.58 Å) H–O bond length. In the twenty-first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the twenty-second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the twenty-third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the twenty-fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the eighth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the ninth O2- site, O2- is bonded in a distorted water-like geometry to two Al3+ atoms. In the tenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the eleventh O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and two H1+ atoms. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to two Al3+ and two H1+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fourteenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the fifteenth O2- site, O2- is bonded in a 3-coordinate geometry to two Al3+ and one H1+ atom. In the sixteenth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the seventeenth O2- site, O2- is bonded in a distorted water-like geometry to two Al3+ and two H1+ atoms. In the eighteenth O2- site, O2- is bonded in a distorted water-like geometry to two Al3+ and two H1+ atoms. In the nineteenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the twentieth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the twenty-first O2- site, O2- is bonded in a 1-coordinate geometry to two Al3+ and one H1+ atom. In the twenty-second O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the twenty-third O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the twenty-fourth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al(NCl)3 by Materials Project

Al(N2Cl)2Al(NCl2)2 crystallizes in the triclinic P-1 space group. The structure is one-dimensional and consists of one Al(N2Cl)2 ribbon oriented in the (1, 0, 0) direction and one Al(NCl2)2 ribbon oriented in the (1, 0, 0) direction. In the Al(N2Cl)2 ribbon, Al3+ is bonded in a distorted octahedral geometry to four N and two equivalent Cl1- atoms. There is two shorter (1.90 Å) and two longer (1.95 Å) Al–N bond length. Both Al–Cl bond lengths are 2.75 Å. There are two inequivalent N sites. In the first N site, N is bonded in a distorted bent 120 degrees geometry to one Al3+ and one Cl1- atom. The N–Cl bond length is 1.60 Å. In the second N site, N is bonded in a single-bond geometry to one Al3+ atom. Cl1- is bonded in a distorted water-like geometry to one Al3+ and one N atom. In the Al(NCl2)2 ribbon, Al3+ is bonded in a distorted octahedral geometry to two equivalent N and four Cl1- atoms. Both Al–N bond lengths are 1.93 Å. There are two shorter (2.20 Å) and two longer (2.75 Å) Al–Cl bond lengths. N is bonded in a 2-coordinate geometry to one Al3+ and one Cl1- atom. The N–Cl bond length is 1.61 Å. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Al3+ atom. In the second Cl1- site, Cl1- is bonded in a bent 120 degrees geometry to one Al3+ and one N atom.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Additively-manufactured Al-0.3Zr-0.2Ce-0.2Cu alloy with high creep resistance and electrical conductivity

Here, a new, solute-lean Al-0.3Zr-0.2Ce-0.2Cu (wt.%) alloy is developed for additive manufacturing that overcomes the classical tradeoff between conductivity and creep resistance. The rapid-cooling-enabled supersaturation of Zr, and its uniform distribution in α-Al matrix, along with formation of submicron (Ce,Cu)-rich intermetallic particles on solidification lead to unusually high creep resistance at 200 °C. Near-zero secondary creep rates are achieved up to the alloy yield stress (YS) of 65 MPa at 200 °C in as-fabricated state. The Zr-solute-induced dislocation-climb suppression mechanism underlying this improvement also restricts dynamic recovery above YS, as noted from appreciable primary creep and its transitioning to near-zero secondary creep rates. A combination of relatively coarse, epitaxially-grown α-Al grains, low Zr concentration in α-Al, and the impurity-scavenging effect of Ce to purify α-Al matrix produces high electrical conductivity of ∼48 %IACS. Aging precipitation of L1 2 -Al 3 Zr nanoprecipitates doubles the YS (to ∼150 MPa) at room temperature and increases alloy conductivity to ∼58 %IACS, but loss of solid-solution Zr out of α-Al matrix leads to activation of dislocation climb, degrading the creep properties as compared to the supersaturated Al-Zr solid solution in the as-fabricated state. Compared to L1 2 -Al 3 Zr nanoprecipitates, submicron (Ce,Cu)-rich particles formed on solidification are more effective at impeding dislocation climb, producing a threshold stress for dislocation creep of ∼ 50 MPa at 200 °C. The new alloy design concepts, especially solute-induced dislocation-climb suppression for creep resistance, explored here may pave way for the design of new metallic alloys for thermal/electrical conductors and other high-temperature applications.

Additive Manufacturing↗
DOE OSTI2023

Microstructural evolution of rapidly solidified hypoeutectic Al 10Cu alloy during non-isothermal annealing transients induced by nano-second laser pulses

The evolution of characteristic nonequilibrium features presenting in morphologically distinct regions of rapid solidification (RS) microstructures in a hypoeutectic Al—10Cu (atomic %) in response to non-isothermal annealing transients has been studied by transmission electron microscopy (TEM). The capabilities of the Movie-Mode Dynamic TEM (MM-DTEM) instrument were used to expose select regions of the RS microstructure to sequences of rapid heating and cooling transients induced by nanosecond laser pulses while permitting in-situ observation. Partial melting, microstructural scale coarsening, morphological changes of the nonequilibrium features in the multi-phase RS microstructure, and solid-state phase transformation were observed. Heterogeneous nucleation of nanoscale θ-Al 2 Cu phase involved metastable supersaturated α-Al and the θ'-Al 2 Cu phases, establishing different sets of orientation relationships for the stable θ-Al 2 Cu and α-Al phases. Replacement of banded morphology grains that formed under conditions driven farthest from equilibrium by an equiaxed nanocrystalline structure comprised of α-Al phase, the primary solidification product, and an intergranular network of Al 2 Cu crystals has been attributed to local remelting. Here the experimental approach explored, permitted discovery of mechanistic details of location-specific transformation pathways activated in the multi-phase RS microstructure of hypoeutectic Al—Cu during subsequent nonisothermal transients.

36 MATERIALS SCIENCE↗