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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Study of the Alsys implementation of the Catalogue of Interface Features and Options for the Ada language for 80386 Unix

A set of programs was written to test the functionality and performance of the Alsys Ada implementation of the Catalogue of Interface Features and Options (CIFO), a set of optional Ada packages for real-time applications. No problems were found with the task id, preemption control, or shared-data packages. Minor problems were found with the dispatching control, dynamic priority, events, non-waiting entry call, semaphore, and scheduling packages. The Alsys implementation is derived mostly from Release 2 of the CIFO standard, but includes some of the features of Release 3 and some modifications unique to Alsys. Performance measurements show that the semaphore and shared-data features are an order-of-magnitude faster than the same mechanisms using an Ada rendezvous. The non-waiting entry call is slightly faster than a standard rendezvous. The existence of errors in the implementation, the incompleteness of the documentation from the published standard impair the usefulness of this implementation. Despite those short-comings, the Alsys CIFO implementation might be of value in the development of real-time applications.

Gibson, James S.↗
DOE OSTI2025

Magnetism in EuAlSi and the Eu 1−𝑥 ⁢Sr 𝑥 ⁢ AlSi solid solution solid solution

The magnetic properties of EuAlSi, a compound comprising a honeycomb lattice of Al/Si atoms and a triangular lattice of Eu atoms, are presented. By means of single-crystal x-ray diffraction, we find that EuAlSi crystallizes in an AlB 2 -type structure with space group 𝑃⁢6/mmm and unit cell parameters 𝑎 = 4.2229⁢ (10) ⁢Å and 𝑐 = 4.5268 ⁢(12)⁢ Å. Our magnetic measurements indicate that EuAlSi is a soft ferromagnetic material with 𝑇 Curie = 25.8 K. The susceptibility follows the Curie-Weiss law at high temperatures, which allowed us to determine the paramagnetic Curie temperature 𝜃 𝑃 = 36.2 ⁢(1) ⁢K and an effective magnetic moment 𝜇 eff = 8.07 ⁢(1)⁢ µ 𝐵 /Eu. This value is in agreement with the theoretical value of 7.9 µ 𝐵 for Eu 2+ free ion. Moreover, we have prepared the Eu 1−𝑥 ⁢Sr 𝑥 ⁢ AlSi solid solution, where the atoms in the triangular lattice were systematically exchanged, in order to study the evolution of the collective quantum properties from the ferromagnetic EuAlSi toward the superconducting SrAlSi. Across the Eu 1−𝑥 ⁢Sr 𝑥 AlSi solid solution, the unit cell parameters change linearly, following Vegard’s law, and making the system reliable for studying composition dependence of the interplay between the crystal structure and physical properties. As the Sr content increases, i.e., 𝑥 increases, we note a consistent reduction of 𝜇 eff and 𝑇 Curie . Long-range magnetic order in Eu 1−𝑥 ⁢Sr 𝑥 ⁢ AlSi persists up to 𝑥 = 0.95, whereas superconductivity is only observed for samples with 𝑥 > 0.97.

Walicka, Dorota I. [University of Geneva (Switzerl↗
DOE OSTI2022

Modeling deformation and failure in AlSi-polyester abradable sealcoating material using microstructure-based finite element simulation

A plasma-sprayed aluminum-silicon (AlSi)/polyester coating is applied in modern gas turbine engines as an abradable sealcoating to maintain tight clearances between the rotating blades and the static casing. While running the engine, the rotating blades “rub” with the abradable coating, which results in extreme strain rate (up to 10 6 ) dynamics and a high-temperature environment. Due to the difficulty of collecting direct measurements, predictive computational models are important for analyzing the deformation and failure of the abradable material, to help meet the design target of avoiding damage to the blade tip and maintaining high fuel efficiency. In this research, a microstructure-based finite element (FE) computational model was developed to capture the complex mechanical behavior of the AlSi/polyester microstructure. The model is based on a virtual representative-volume-element (RVE) of a metal-polymer microstructure, reconstructed from x-ray computed tomography. It models the plastic deformation of, and damage to, each AlSi and polyester constituents, as well as the failure at their interface. The model was calibrated and validated with uniaxial tension and compression experiments, conducted at two temperatures (298 K and 533 K) at an applied strain rate of 10 3 - 10 4 s -1 . The material exhibited strongly asymmetric tension-compression behavior and a sensitivity to temperature, which was well captured by the model. The model was further applied to investigate changes in mechanical behavior due to variations in constituents’ volume fractions, which provides guidance to the microstructural design of AlSi/polyester abradable materials. The model is expected to facilitate the development of improved abradable materials by bypassing the conventional trial-and-error approach and extensive testing requirements.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

The Effect of Sulfuric Acid Anodization on the Electrochemical Properties of Aluminum Alloy AlSi 10 Mg Prepared by Selective Laser Melting

Aluminum alloy, AlSi 10 Mg, prepared by selective laser melt (SLM) fabrication was anodized in 9.8% sulfuric acid (Type II) at 15 V for a total of 23 min. Experiments were performed to study the potentiostatic anodization process and its effects on the oxide coating morphology, thickness, and electrochemical properties of the alloy. Prior to anodization, the alloy microstructure is composed of aluminum cells encapsulated in a silicon network. Anodizing the abraded and polished AlSi 10 Mg surface produced a porous oxide layer with a thickness of 5μm. The oxide coating weight was 698 ± 29 mg/ft 2 . The oxide coating forms in the aluminum cells that are isolated from one another by the silicon eutectic phase. In electrochemical tests, the anodic and cathodic potentiodynamic polarization currents were suppressed by factors of 15× and 215×, respectively, as compared to the unanodized controls. The data indicate the anodic oxide coating suppresses the cathodic more than the anodic reaction rate. Linear polarization resistance (R p ) values increased by 279× after anodization. The corrosion current density values (j corr ) decreased by 133× after anodization. Taken together, the electrochemical data indicate the anodic oxide coating (unsealed) increases the corrosion resistance of the SLM alloy by two orders of magnitude.

Electrochemistry↗
DOE OSTI2020

Materials Data on Gd(AlSi)2 by Materials Project

Gd(AlSi)2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Gd is bonded to six equivalent Si atoms to form distorted GdSi6 octahedra that share corners with twelve equivalent AlSi4 tetrahedra, edges with six equivalent GdSi6 octahedra, and edges with six equivalent AlSi4 tetrahedra. All Gd–Si bond lengths are 2.99 Å. Al is bonded to four equivalent Si atoms to form distorted AlSi4 tetrahedra that share corners with six equivalent GdSi6 octahedra, corners with six equivalent AlSi4 tetrahedra, edges with three equivalent GdSi6 octahedra, and edges with three equivalent AlSi4 tetrahedra. The corner-sharing octahedra tilt angles range from 21–54°. There are three shorter (2.51 Å) and one longer (2.54 Å) Al–Si bond lengths. Si is bonded to three equivalent Gd and four equivalent Al atoms to form a mixture of distorted corner and edge-sharing SiGd3Al4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca3(AlSi)2 by Materials Project

Ca3(AlSi)2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are two inequivalent Ca sites. In the first Ca site, Ca is bonded to eight equivalent Al and four equivalent Si atoms to form a mixture of distorted edge and face-sharing CaAl8Si4 cuboctahedra. All Ca–Al bond lengths are 3.31 Å. All Ca–Si bond lengths are 3.51 Å. In the second Ca site, Ca is bonded in a 7-coordinate geometry to two equivalent Al and five equivalent Si atoms. Both Ca–Al bond lengths are 3.15 Å. There are one shorter (3.14 Å) and four longer (3.15 Å) Ca–Si bond lengths. Al is bonded in a 2-coordinate geometry to six Ca, one Al, and two equivalent Si atoms. The Al–Al bond length is 2.55 Å. Both Al–Si bond lengths are 2.48 Å. Si is bonded in a 7-coordinate geometry to seven Ca and two equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba3(AlSi)2 by Materials Project

Ba3(AlSi)2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are two inequivalent Ba sites. In the first Ba site, Ba is bonded to eight equivalent Al and four equivalent Si atoms to form a mixture of face and edge-sharing BaAl8Si4 cuboctahedra. All Ba–Al bond lengths are 3.60 Å. All Ba–Si bond lengths are 3.71 Å. In the second Ba site, Ba is bonded in a 7-coordinate geometry to two equivalent Al and five equivalent Si atoms. Both Ba–Al bond lengths are 3.52 Å. There are four shorter (3.51 Å) and one longer (3.66 Å) Ba–Si bond lengths. Al is bonded in a 2-coordinate geometry to six Ba, one Al, and two equivalent Si atoms. The Al–Al bond length is 2.61 Å. Both Al–Si bond lengths are 2.56 Å. Si is bonded in a 2-coordinate geometry to seven Ba and two equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AlSi by Materials Project

AlSi is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Al is bonded in a body-centered cubic geometry to eight equivalent Si atoms. All Al–Si bond lengths are 2.73 Å. Si is bonded in a body-centered cubic geometry to eight equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U2(AlSi)3 by Materials Project

U2(AlSi)3 crystallizes in the orthorhombic Pmmm space group. The structure is three-dimensional. U is bonded to six Al and six Si atoms to form UAl6Si6 cuboctahedra that share corners with twelve equivalent UAl6Si6 cuboctahedra, edges with four equivalent SiU4Al8 cuboctahedra, edges with twelve AlU4Al2Si6 cuboctahedra, faces with two equivalent SiU4Al8 cuboctahedra, faces with six equivalent UAl6Si6 cuboctahedra, and faces with six AlU4Al2Si6 cuboctahedra. All U–Al bond lengths are 2.98 Å. There are a spread of U–Si bond distances ranging from 2.83–2.95 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded to four equivalent U, two equivalent Al, and six Si atoms to form AlU4Al2Si6 cuboctahedra that share corners with twelve equivalent AlU4Al2Si6 cuboctahedra, edges with four equivalent AlU4Al4Si4 cuboctahedra, edges with four equivalent SiU4Al8 cuboctahedra, edges with eight equivalent UAl6Si6 cuboctahedra, faces with two equivalent SiU4Al8 cuboctahedra, faces with four equivalent UAl6Si6 cuboctahedra, and faces with eight AlU4Al2Si6 cuboctahedra. Both Al–Al bond lengths are 2.89 Å. There are a spread of Al–Si bond distances ranging from 2.88–2.93 Å. In the second Al site, Al is bonded to four equivalent U, four equivalent Al, and four equivalent Si atoms to form AlU4Al4Si4 cuboctahedra that share corners with four equivalent AlU4Al4Si4 cuboctahedra, edges with eight equivalent UAl6Si6 cuboctahedra, edges with eight equivalent AlU4Al2Si6 cuboctahedra, faces with four equivalent UAl6Si6 cuboctahedra, faces with four equivalent SiU4Al8 cuboctahedra, and faces with eight AlU4Al2Si6 cuboctahedra. All Al–Si bond lengths are 2.98 Å. There are three inequivalent Si sites. In the first Si site, Si is bonded in a distorted body-centered cubic geometry to four equivalent U and four equivalent Al atoms. In the second Si site, Si is bonded to four equivalent U and eight Al atoms to form SiU4Al8 cuboctahedra that share corners with four equivalent SiU4Al8 cuboctahedra, edges with eight equivalent UAl6Si6 cuboctahedra, edges with eight equivalent AlU4Al2Si6 cuboctahedra, faces with four equivalent UAl6Si6 cuboctahedra, faces with four equivalent SiU4Al8 cuboctahedra, and faces with eight AlU4Al2Si6 cuboctahedra. In the third Si site, Si is bonded in a distorted body-centered cubic geometry to four equivalent U and four equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La(AlSi)2 by Materials Project

La(AlSi)2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. La2+ is bonded to six equivalent Si4- atoms to form LaSi6 octahedra that share corners with twelve equivalent AlSi4 tetrahedra, edges with six equivalent LaSi6 octahedra, and edges with six equivalent AlSi4 tetrahedra. All La–Si bond lengths are 3.11 Å. Al3+ is bonded to four equivalent Si4- atoms to form AlSi4 tetrahedra that share corners with six equivalent LaSi6 octahedra, corners with six equivalent AlSi4 tetrahedra, edges with three equivalent LaSi6 octahedra, and edges with three equivalent AlSi4 tetrahedra. The corner-sharing octahedra tilt angles range from 23–52°. There are three shorter (2.53 Å) and one longer (2.54 Å) Al–Si bond lengths. Si4- is bonded to three equivalent La2+ and four equivalent Al3+ atoms to form a mixture of distorted edge and corner-sharing SiLa3Al4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf10(AlSi)3 by Materials Project

Hf10(AlSi)3 crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. there are three inequivalent Hf sites. In the first Hf site, Hf is bonded in a 6-coordinate geometry to three equivalent Al and three equivalent Si atoms. All Hf–Al bond lengths are 2.84 Å. All Hf–Si bond lengths are 2.83 Å. In the second Hf site, Hf is bonded in a 5-coordinate geometry to three equivalent Al and two equivalent Si atoms. There are two shorter (2.74 Å) and one longer (2.89 Å) Hf–Al bond lengths. Both Hf–Si bond lengths are 3.03 Å. In the third Hf site, Hf is bonded in a 5-coordinate geometry to two equivalent Al and three equivalent Si atoms. Both Hf–Al bond lengths are 3.04 Å. There are two shorter (2.73 Å) and one longer (2.91 Å) Hf–Si bond lengths. Al is bonded in a 9-coordinate geometry to nine Hf atoms. Si is bonded in a 9-coordinate geometry to nine Hf atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y(AlSi)2 by Materials Project

YAl2Si2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Y is bonded to six equivalent Si atoms to form distorted YSi6 octahedra that share corners with twelve equivalent AlSi4 tetrahedra, edges with six equivalent YSi6 octahedra, and edges with six equivalent AlSi4 tetrahedra. All Y–Si bond lengths are 2.97 Å. Al is bonded to four equivalent Si atoms to form distorted AlSi4 tetrahedra that share corners with six equivalent YSi6 octahedra, corners with six equivalent AlSi4 tetrahedra, edges with three equivalent YSi6 octahedra, and edges with three equivalent AlSi4 tetrahedra. The corner-sharing octahedra tilt angles range from 21–55°. There are three shorter (2.51 Å) and one longer (2.53 Å) Al–Si bond lengths. Si is bonded to three equivalent Y and four equivalent Al atoms to form a mixture of distorted edge and corner-sharing SiY3Al4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tb(AlSi)2 by Materials Project

TbAl2Si2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Tb is bonded to six equivalent Si atoms to form distorted TbSi6 octahedra that share corners with twelve equivalent AlSi4 tetrahedra, edges with six equivalent TbSi6 octahedra, and edges with six equivalent AlSi4 tetrahedra. All Tb–Si bond lengths are 2.98 Å. Al is bonded to four equivalent Si atoms to form distorted AlSi4 tetrahedra that share corners with six equivalent TbSi6 octahedra, corners with six equivalent AlSi4 tetrahedra, edges with three equivalent TbSi6 octahedra, and edges with three equivalent AlSi4 tetrahedra. The corner-sharing octahedra tilt angles range from 21–55°. There are three shorter (2.51 Å) and one longer (2.53 Å) Al–Si bond lengths. Si is bonded to three equivalent Tb and four equivalent Al atoms to form a mixture of distorted edge and corner-sharing SiTb3Al4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(AlSi)2 by Materials Project

PrAl2Si2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Pr is bonded to six equivalent Si atoms to form distorted PrSi6 octahedra that share corners with twelve equivalent AlSi4 tetrahedra, edges with six equivalent PrSi6 octahedra, and edges with six equivalent AlSi4 tetrahedra. All Pr–Si bond lengths are 3.08 Å. Al is bonded to four equivalent Si atoms to form distorted AlSi4 tetrahedra that share corners with six equivalent PrSi6 octahedra, corners with six equivalent AlSi4 tetrahedra, edges with three equivalent PrSi6 octahedra, and edges with three equivalent AlSi4 tetrahedra. The corner-sharing octahedra tilt angles range from 23–53°. There are three shorter (2.53 Å) and one longer (2.54 Å) Al–Si bond lengths. Si is bonded to three equivalent Pr and four equivalent Al atoms to form a mixture of distorted edge and corner-sharing SiPr3Al4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(AlSi)2 by Materials Project

BaAl2Si2 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ba2+ is bonded in a body-centered cubic geometry to eight equivalent Si4- atoms. All Ba–Si bond lengths are 3.47 Å. Al3+ is bonded to four equivalent Si4- atoms to form a mixture of corner and edge-sharing AlSi4 tetrahedra. All Al–Si bond lengths are 2.56 Å. Si4- is bonded in a 8-coordinate geometry to four equivalent Ba2+ and four equivalent Al3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(AlSi)2 by Materials Project

EuAl2Si2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Eu2+ is bonded to six equivalent Si4- atoms to form EuSi6 octahedra that share corners with twelve equivalent AlSi4 tetrahedra, edges with six equivalent EuSi6 octahedra, and edges with six equivalent AlSi4 tetrahedra. All Eu–Si bond lengths are 3.07 Å. Al3+ is bonded to four equivalent Si4- atoms to form AlSi4 tetrahedra that share corners with six equivalent EuSi6 octahedra, corners with six equivalent AlSi4 tetrahedra, edges with three equivalent EuSi6 octahedra, and edges with three equivalent AlSi4 tetrahedra. The corner-sharing octahedra tilt angles range from 21–52°. There are three shorter (2.53 Å) and one longer (2.59 Å) Al–Si bond lengths. Si4- is bonded to three equivalent Eu2+ and four equivalent Al3+ atoms to form a mixture of distorted edge and corner-sharing SiEu3Al4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(AlSi)2 by Materials Project

MgAl2Si2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Mg2+ is bonded to six equivalent Si4- atoms to form MgSi6 octahedra that share corners with twelve equivalent AlSi4 tetrahedra, edges with six equivalent MgSi6 octahedra, and edges with six equivalent AlSi4 tetrahedra. All Mg–Si bond lengths are 2.86 Å. Al3+ is bonded to four equivalent Si4- atoms to form AlSi4 tetrahedra that share corners with six equivalent MgSi6 octahedra, corners with six equivalent AlSi4 tetrahedra, edges with three equivalent MgSi6 octahedra, and edges with three equivalent AlSi4 tetrahedra. The corner-sharing octahedra tilt angles range from 16–55°. There are three shorter (2.49 Å) and one longer (2.61 Å) Al–Si bond lengths. Si4- is bonded to three equivalent Mg2+ and four equivalent Al3+ atoms to form a mixture of distorted corner and edge-sharing SiMg3Al4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(AlSi)2 by Materials Project

BaAl2Si2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Ba2+ is bonded in a 7-coordinate geometry to seven Si4- atoms. There are a spread of Ba–Si bond distances ranging from 3.29–3.62 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four Si4- atoms to form a mixture of corner and edge-sharing AlSi4 tetrahedra. There are three shorter (2.56 Å) and one longer (2.58 Å) Al–Si bond lengths. In the second Al3+ site, Al3+ is bonded to four Si4- atoms to form a mixture of corner and edge-sharing AlSi4 tetrahedra. There are a spread of Al–Si bond distances ranging from 2.52–2.58 Å. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 4-coordinate geometry to four equivalent Ba2+ and four Al3+ atoms. In the second Si4- site, Si4- is bonded in a 7-coordinate geometry to three equivalent Ba2+ and four Al3+ atoms.

36 MATERIALS SCIENCE↗