SEARCH · Search NASA

Results for “Al8Cr5”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

2 records

All sources NASA NTRS DOE OSTI

DOE OSTI2020

Materials Data on Al8Cr5 by Materials Project

Al8Cr5 is Bergman Structure: Mg32(Al,Zn)49 Bergman-derived structured and crystallizes in the trigonal R3m space group. The structure is three-dimensional. there are four inequivalent Cr sites. In the first Cr site, Cr is bonded in a 12-coordinate geometry to nine Cr and three equivalent Al atoms. There are a spread of Cr–Cr bond distances ranging from 2.30–2.71 Å. All Cr–Al bond lengths are 2.61 Å. In the second Cr site, Cr is bonded in a 12-coordinate geometry to six Cr and six Al atoms. There are three shorter (2.58 Å) and two longer (2.81 Å) Cr–Cr bond lengths. There are a spread of Cr–Al bond distances ranging from 2.51–2.72 Å. In the third Cr site, Cr is bonded in a 12-coordinate geometry to five Cr and seven Al atoms. Both Cr–Cr bond lengths are 2.82 Å. There are a spread of Cr–Al bond distances ranging from 2.55–2.64 Å. In the fourth Cr site, Cr is bonded in a 12-coordinate geometry to four Cr and eight Al atoms. There are a spread of Cr–Al bond distances ranging from 2.60–2.88 Å. There are five inequivalent Al sites. In the first Al site, Al is bonded in a distorted cuboctahedral geometry to three equivalent Cr and nine Al atoms. There are a spread of Al–Al bond distances ranging from 2.68–2.77 Å. In the second Al site, Al is bonded in a 1-coordinate geometry to four Cr and nine Al atoms. There are a spread of Al–Al bond distances ranging from 2.62–3.04 Å. In the third Al site, Al is bonded in a 12-coordinate geometry to four Cr and eight Al atoms. There are a spread of Al–Al bond distances ranging from 2.71–2.86 Å. In the fourth Al site, Al is bonded in a 11-coordinate geometry to three Cr and eight Al atoms. Both Al–Al bond lengths are 2.92 Å. In the fifth Al site, Al is bonded in a 12-coordinate geometry to five Cr and six Al atoms. Both Al–Al bond lengths are 2.79 Å.

36 MATERIALS SCIENCE↗

DOE OSTI2026

Thermodynamics of Tritium Trapping by Point Defects at Interfacial Cr-based Phases of the Al Coating

Density functional theory (DFT) simulations have been carried out to evaluate the potential for tritium trapping by metal vacancies in four phases Cr-containing phases (i.e., Cr3Si, Al0.3Cr0.7, Al8Cr5-HT, and Al8Cr5) identified near the interface between the Al coating and 316 stainless steel (316 SS) cladding. In addition, an ab initio thermodynamics approach has been employed to predict the temperature and T2-partial pressure dependence on the thermodynamics of singly tritiated defects. Key results in this work suggest that metal vacancies in the four phases have the potential to favorably trap tritium species, especially Si vacancies in Cr3Si phase. This overall thermodynamic trend can be correlated to the energy cost of having an interstitial tritium in the lattice, which has been calculated to range from 0.17 eV in Al8Cr5-HT to 0.89 eV in Cr3Si. A comparison of the results from this study with previous theoretical works investigating tritium behavior in other Fe-Al phases identified in the aluminide coating, suggests that metal vacancies are generally able to trap tritium in various Fe-Al aluminide phases. Especially, it was found that Si and Al vacancies would be the most efficient to trap for tritium, followed by Cr vacancies, then Fe and Ni vacancies. In the four Cr-based material phases investigated in this work, it is interesting to note that, in the absences of Fe or Ni species, strong interactions between tritium and the metal vacancies are always occurring by the formation of preferential Cr—T bonds (i.e., no Si—T or Al—T bonds were formed).

Sassi, Michel J.↗