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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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8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Surface Film Formation on Al-V Alloys with Far-From-Equilibrium Microstructure

Nanocrystalline supersaturated Al-V alloys produced by high-energy ball milling have been reported to exhibit enhanced corrosion resistance and mechanical properties compared to commercial Al alloys. Corrosion of passive alloys such as Al-V alloy relies on the characteristics of the surface film, which is studied using scanning/transmission electron microscopy and time-of-flight secondary ion mass spectrometry. The effect of microstructure and composition on the surface film has been investigated after different immersion periods (30 min, 2 h, and 1 day) in 0.1 M NaCl. The surface film was complex and composed of oxidized Al and V. The heterogeneous surface film was observed due to the presence of secondary phases and initiation of localized corrosion. The void formation was observed beneath the surface film that would potentially cause pitting corrosion. The generation of nano-sized voids was dependent on grain orientation. Compared to pure Al, the chloride penetration is suppressed in Al-V alloys. The effect of composition and microstructure on surface film formation and attendant corrosion behavior is discussed herein.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Effect of V Content on Corrosion Behavior of Al-V Alloys Produced by Mechanical Alloying and Subsequent Spark Plasma Sintering

Al-V alloys produced via high-energy ball milling have been reported to show simultaneous improvement of corrosion resistance and mechanical properties compared to traditional Al alloys. In these alloys, V content plays a crucial role in increasing or decreasing the corrosion resistance. Therefore, the effect of V and microstructure on corrosion of high-energy ball milled and subsequently spark plasma sintered Al-xV alloys (x = 2, 5, 10 at%) has been studied. Cyclic potentiodynamic polarization tests and electrochemical impedance spectroscopic analysis revealed the increment of V content up to 5 at% enhanced the corrosion resistance of the alloy. However, highly heterogeneous microstructure in Al-10 at%V resulted in significant localized corrosion over the immersion time. The electrochemical impedance spectroscopy studies over 14 days of immersion revealed underlying corrosion mechanisms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Relative phase stability of L1 2 and DO 22 /DO 23 structures in Al 3 Nb, Al 3 Zr and Al 3 V compounds

The relative stability of the different tri-aluminide (Al 3 M) phases in three binary systems (M = Zr, Nb and V) was assessed for their potential to form fine cubic L1 2 precipitates in additively manufactured alloys. Supersaturated thin films of Al-(8–30) at% M were sputtered and heat treated during in-situ x-ray diffraction (XRD) measurements to observe the temperature ranges of stability for each phase. As-sputtered films were then processed with laser tracks simulating additive manufacturing solidification conditions, and the formation of phases in the laser tracks was correlated with density functional theory (DFT) and nucleation rate calculations. We found that the metastable L1 2 structure is highly competitive with the stable DO 23 structure in the Al-Zr system, but much less stable than the DO 22 structure in the Al-Nb system, and both the DO 22 and Al 8 V 5 structure in the Al-V system. Furthermore, these experimental results were found to be in good agreement with the DFT and kinetic calculations, as we determined that the metastable L1 2 in Al-Zr only requires a small amount of undercooling to favor its nucleation over the stable DO 23 , suggesting additive manufacturing can be a viable pathway to develop Al-Zr alloys strengthened by a high volume fraction of L1 2 Al 3 Zr phase.

Perrin, Alice E. [Oak Ridge National Laboratory (O↗
DOE OSTI2025

First-principles thermodynamics of Al 10 ⁢V: An analytical treatment of localized anharmonic modes

Many complex intermetallic structures possess cagelike environments that can host additional guest atoms. In Al 10 ⁢V, these atoms give rise to low-frequency, localized vibrations (Einstein modes) that dominate the thermodynamic response at low temperature. They become imaginary under volume expansion as temperature rises, invalidating the harmonic approximation. Here, we develop a framework to incorporate these strongly anharmonic vibrational modes into first-principles thermodynamic calculations. By explicitly modeling the cage potential and solving the associated Schrödinger equation numerically, we compute the full anharmonic free energy contribution and demonstrate its impact on the thermodynamic behavior of Al 10⁢ V. This allows us to examine structures with different cage fillings and construct the Al-V phase diagram in the relevant composition range. Our results reproduce key experimental signatures, including the anomalous rise in the thermal expansion coefficient and heat capacity at low temperatures, and reveal that the presence and the extent of cage filling by guest atoms is essential to stabilizing the Al 10 ⁢V phase at elevated temperatures.

anharmonic lattice dynamics↗
DOE OSTI2020

Materials Data on AlV3 by Materials Project

V3Al crystallizes in the cubic Pm-3n space group. The structure is three-dimensional. V is bonded in a 6-coordinate geometry to ten equivalent V and four equivalent Al atoms. There are two shorter (2.40 Å) and eight longer (2.95 Å) V–V bond lengths. All V–Al bond lengths are 2.69 Å. Al is bonded to twelve equivalent V atoms to form a mixture of face and edge-sharing AlV12 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al3V by Materials Project

Al3V crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. V is bonded to twelve Al atoms to form VAl12 cuboctahedra that share corners with four equivalent VAl12 cuboctahedra, corners with eight equivalent AlAl8V4 cuboctahedra, edges with eight equivalent VAl12 cuboctahedra, edges with sixteen equivalent AlAl8V4 cuboctahedra, faces with four equivalent VAl12 cuboctahedra, and faces with fourteen AlAl8V4 cuboctahedra. There are four shorter (2.66 Å) and eight longer (2.80 Å) V–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded to four equivalent V and eight equivalent Al atoms to form AlAl8V4 cuboctahedra that share corners with four equivalent AlAl8V4 cuboctahedra, corners with eight equivalent VAl12 cuboctahedra, edges with twenty-four AlAl8V4 cuboctahedra, faces with six equivalent VAl12 cuboctahedra, and faces with twelve AlAl8V4 cuboctahedra. All Al–Al bond lengths are 2.80 Å. In the second Al site, Al is bonded to four equivalent V and eight Al atoms to form AlAl8V4 cuboctahedra that share corners with twelve equivalent AlAl8V4 cuboctahedra, edges with eight equivalent VAl12 cuboctahedra, edges with sixteen AlAl8V4 cuboctahedra, faces with four equivalent VAl12 cuboctahedra, and faces with fourteen AlAl8V4 cuboctahedra. All Al–Al bond lengths are 2.66 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al3V by Materials Project

Al3V is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. V is bonded to twelve equivalent Al atoms to form VAl12 cuboctahedra that share corners with twelve equivalent VAl12 cuboctahedra, edges with twenty-four equivalent AlAl8V4 cuboctahedra, faces with six equivalent VAl12 cuboctahedra, and faces with twelve equivalent AlAl8V4 cuboctahedra. All V–Al bond lengths are 2.76 Å. Al is bonded to four equivalent V and eight equivalent Al atoms to form AlAl8V4 cuboctahedra that share corners with twelve equivalent AlAl8V4 cuboctahedra, edges with eight equivalent VAl12 cuboctahedra, edges with sixteen equivalent AlAl8V4 cuboctahedra, faces with four equivalent VAl12 cuboctahedra, and faces with fourteen equivalent AlAl8V4 cuboctahedra. All Al–Al bond lengths are 2.76 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al8V5 by Materials Project

Al8V5 is gamma-brass structured and crystallizes in the cubic I-43m space group. The structure is three-dimensional. there are two inequivalent V sites. In the first V site, V is bonded in a 4-coordinate geometry to three V and ten Al atoms. There are two shorter (2.76 Å) and one longer (2.83 Å) V–V bond lengths. There are a spread of V–Al bond distances ranging from 2.60–2.95 Å. In the second V site, V is bonded in a 12-coordinate geometry to three equivalent V and nine Al atoms. There are a spread of V–Al bond distances ranging from 2.62–2.78 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded in a 12-coordinate geometry to six V and six Al atoms. There are three shorter (2.81 Å) and three longer (2.90 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 11-coordinate geometry to six V and five Al atoms. All Al–Al bond lengths are 2.69 Å.

36 MATERIALS SCIENCE↗