Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Al alloy”

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.

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

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Chromium-Free Coating for Al Alloy Corrosion Protection Based on a Novel Ti/Mg Oxyfluoride

Chromium-free corrosion protection of aluminum alloys comparable to that of chromates (Cr(VI)) is demonstrated using a TiF 6 2– fluoro-anion-based coating recipe containing boric acid and a Mg salt. Boric acid drove TiF 6 2– hydrolysis enabling up to micrometer-scale thick coatings. The Mg salt led to deposition of a novel crystalline phase Ti/Mg oxyfluoride coating with an approximate composition of Ti 5 MgO 7 F 8 . Corrosion protection performance was characterized by polarization resistance measurements during immersion in 5% aqueous NaCl solution and neutral salt fog exposure following ASTM B.117. The performance is discussed in terms of the presence of fluoride in the coating enabling active behavior during its gradual depletion (in corrosion environments) toward a final composition approaching TiO 2 . This active corrosion protection mechanism may be more generally applicable for transition metal-based coatings that do not have high oxidation state oxo-anions, but do have stable fluoro-anions.

36 MATERIALS SCIENCE↗
DOE OSTI2025

CABLE Stage 3 – Ultra‐High Strength/Highly Conductive Al Alloys

This work is to be conducted in support of the CABLE Conductor Manufacturing Prize Program awarded by NREL. The intent is to connect competitor teams with national laboratories that can help accelerate the development of innovative solutions and products. Teams who receive CABLE Prize awards are eligible to utilize vouchers at national laboratories to advance their ideas. NanoAL LLC has been awarded a voucher to utilize at Ames National Laboratory. Ames National Laboratory will perform a scale‐up trial of Nano 6000‐T9 to evaluate and optimize the heat treatment and other processing variables to validate the lab‐scale work done at NanoAL. The final processing schedule will be used to fabricate the submission samples for the Stage 3 contest. All work will be supported by mechanical and electrical conductivity testing be performed by Ames.

36 MATERIALS SCIENCE↗
NASA NTRS1974

The effect of yttrium and thorium on the oxidation behavior of Ni-Cr-Al alloys

The effect of quaternary additions of 0.5% Y, 0.5 and 1.0% Th to a base alloy of Ni-10CR-5Al on the oxidation behavior and mechanism was studied during oxidation in air over the range of 1000 to 1200 C. The presence of yttrium decreased the oxidation kinetics slightly, whereas, the addition of thorium caused a slight increase. Oxide scale adherence was markedly improved by the addition of the quaternary elements. Although a number of oxides formed on yttrium containing alloys, quantitative X-ray diffraction clearly showed that the rate-controlling step was the diffusion of aluminum through short circuit paths in a thin layer of alumina that formed parabolically with time. Although the scale adherence of the yttrium containing alloy was considerably better than the base alloys, spalling did occur that was attributed to the formation of the voluminous YAG particles which grew in a mushroom-like manner, lifting the protective scale off the subrate locally. The YAG particles formed primarily at grain boundaries in the substrate in which the yttrium originally existed as YNi9.

Kumar, A.↗
NASA NTRS1976

An oxide dispersion strengthened Ni-W-Al alloy with superior high temperature strength

An experimental oxide dispersion strengthened (ODS) alloy, WAZ-D, derived from the WAZ-20 composition was produced by the mechanical alloying process. Cast WAZ-20 is strengthened by both a high refractory metal content, and 70 volume percent of gamma prime. The ODS alloy WAZ-D was responsive to variables of alloy content, of attritor processing, of consolidation by extrusion, and of heat treatment. The best material produced had large highly elongated grains. It exhibited tensile strengths generally superior to a comparable cast alloy. The ODS alloy exhibited high temperature stress rupture life considerably superior to any known cast superalloy. Tensile and rupture ductility were low, as was intermediate temperature rupture life. Very low creep rates were noted and some specimens failed with essentially no third stage creep. Also the benefit derived from the oxide dispersion, far out-weighed that from the elongated microstructure alone.

Glasgow, T. K.↗
NASA NTRS1976

An oxide dispersion strengthened Ni-W-Al alloy with superior high temperature strength

Oxide dispersion strengthened alloys based on the WAZ-20 nickel-base alloy were prepared by the mechanical alloying process described by Benjamin (1973), and evaluated. The results of microstructural examinations and mechanical property determinations are discussed. It is shown that WAZ-20, a high gamma-prime fraction alloy having a high gamma-prime solvus temperature, can be effectively dispersion strengthened. The strengths obtained were outstanding, especially at 1150 and 1205 C. The strength is attributed to a combination of highly alloyed matrix, elongated grain structure, and hard phase dispersion. Tensile ductility can be improved by post-recrystallization heat treatment. The new alloy shows some potential for low stress post-extrusion forming.

Glasgow, T. K.↗
NASA NTRS1987

Microstructure and Aging of Powder-Metallurgy Al Alloys

Report describes experimental study of thermal responses and aging behaviors of three new aluminum alloys. Alloys produced from rapidly solidified powders and contain 3.20 to 5.15 percent copper, 0.24 to 1.73 percent magnesium, 0.08 to 0.92 percent iron, and smaller amounts of manganese, nickel, titanium, silicon, and zinc. Peak hardness achieved at lower aging temperatures than with standard ingot-metallurgy alloys. Alloys of interest for automobile, aircraft, and aerospace applications.

Blackburn, L. B.↗
NASA NTRS1989

Microstructure and tensile properties of Fe-40 at. pct Al alloys with C, Zr, Hf, and B additions

The influence of small additions of C, Zr, and Hf, alone or in combination with B, on the microstructure and tensile behavior of substoichiometric FeAl was investigated. Tensile properties were determined from 300 to 1100 K on powder which was consolidated by hot extrusion. All materials possessed some ductility at room temperature, although ternary additions generally reduced ductility compared to the binary alloy. Adding B to the C- and Zr-containing alloys changed the fracture mode from intergranular to transgranular and restored the ductility to approximately 5 percent elongation. Additions of Zr and Hf increased strength up to about 900 K. Fe6Al6Zr and Fe6Al6Hf precipitates, both with identical body-centered tetragonal structures, were identified as the principal second phase in these alloys. Strength decreased steadily as temperature increased above 700 K, as diffusion-assisted mechanisms became operative. Although all alloys had similar strengths at 1100 K, Hf additions significantly improved high-temperature ductility by suppressing cavitation.

Gaydosh, D. J.↗
DOE OSTI2025

Scale-Up of Friction Self-piercing Riveting Process for Multi-material Joints

A single-class joining process known as “friction self-piercing riveting (F-SPR)” has been developed for joining various low-ductility lightweight materials on a laboratory scale. The frictional heat generated during the F-SPR process improved local ductility, resulting in crack-free joints and robust mechanical performance. This innovative joining technology was further advanced through the scale-up of the process using a new system with several key features (e.g., automatic rivet feeding and clamping system, vacuum system) toward industry readiness. The new integrated F-SPR systems were effectively demonstrated for joining different material combinations (e.g., carbon fiber composite to 7075 Al alloy, 7075 Al alloy to 7075 Al alloy, and 7075 Al alloy to casting Al Aural 5) with a unified technique. Crack-free joint with adequate mechanical interlocking resulted in good mechanical joint strength for each material combination. Then, the process was successfully scaled up by producing multiple joints without any cracks on larger CFC-Al and Al-Al components by the new integrated system, bringing it closer to industrial application.

Lim, Yong Chae [ORNL] (ORCID:0000000321773988)↗
DOE OSTI2024

Dissolution Flowsheet for Non-Aluminum Spent Nuclear Fuel Campaign 1

As part of the Accelerated Basin De-inventory (ABD) program, H Canyon plans to dissolve non-aluminum spent nuclear fuel (NASNF) in the 6.3D electrolytic dissolver. NASNF Campaign 1 plans to electrolytically dissolve 68 bundles of fuel assemblies from the Carolinas-Virginia Tube Reactor (CVTR), Heavy Water Components Test Reactor (HWCTR), and Experimental Boiling Water Reactor (EBWR). The fuel assemblies are intact Zircaloy or stainless steel (SS) clad UO 2 rods, tubes, and plates. The H Canyon electrolytic dissolver previously dissolved a variety of UO 2 core fuel types in SS, Zircaloy, Nichrome, or Incoloy cladding from 1969 to 1980. The objective of this study was to identify flowsheet conditions through literature review and laboratory experimentation to safely dissolve NASNF Campaign 1 bundles in the H Canyon electrolytic dissolver. Bench-scale electrolytic dissolution tests were performed to demonstrate a flowsheet for NASNF Campaign 1 bundles. The outer bundles are composed of SS or Al alloy, Al 6061-T6, and contain intact Zircaloy or SS clad UO 2 fuel assemblies. The key objectives of these tests were to determine bounding dissolver chemistries and the sparge requirement to ensure H 2 concentration remain less than 60 vol % of the lower flammability limit (LFL) during dissolution. The impact of HNO 3 concentration and the addition of fluoride on the dissolution efficiency of Zircaloy, 304L SS, Al 6061-T6, and Inconel 625 were examined. While SS, Al, and Inconel 625 readily dissolve utilizing electrolytic dissolution, Zircaloy disintegrated anodically; the surface of Zircaloy oxidized and the oxide layer spalled off and settled at the bottom of the dissolver as an insoluble material. The black flakes were identified as ZrO 2 and 85% of the Zr processed was converted to black ZrO 2 flakes when Zr was anodically disintegrated in 9.5 M HNO 3 .

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS2008

EBSD and Nanoindentation-Correlated Study of Delamination Fracture in Al-Li Alloy 2090

Al-Li alloys offer attractive combinations of high strength and low density. However, a tendency for delamination fracture has limited their use. A better understanding of the delamination mechanisms may identify methods to control delaminations through processing modifications. A combination of new techniques has been used to evaluate delamination fracture in Al-Li alloys. Both high quality electron backscattered diffraction (EBSD) information and valid nanoindentation measurements were obtained from fractured test specimens. Correlations were drawn between nano-scale hardness variations and local texture along delaminating boundaries. Intriguing findings were observed for delamination fracture through the combined analysis of grain orientation, Taylor factor, and kernel average misorientation.

Tayon, Wesley A.↗
NASA NTRS2002

Effects of Thermal Exposure on Properties of Al-Li Alloys

Aluminum-Lithium (Al-Li) alloys offer significant performance benefits for aerospace structural applications due to their higher specific properties compared with conventional Al alloys. For example, the application of Al-Li alloy 2195 to the space shuffle external cryogenic fuel tank resulted in weight savings of over 7,000 lb, enabling successful deployment of International Space Station components. The composition and heat treatment of 2195 were optimized specifically for strength-toughness considerations for an expendable cryogenic tank. Time-dependent properties related to reliability, such as thermal stability, fatigue, and corrosion, will be of significant interest when materials are evaluated for a reusable cryotank structure. Literature surveys have indicated that there is limited thermal exposure data on Al-Li alloys. The effort reported here was designed to establish the effects of thermal exposure on the mechanical properties and microstructure of Al-Li alloys C458, L277, and 2195 in plate gages. Tensile, fracture toughness, and corrosion resistance were evaluated for both parent metal and friction stir welds (FSW) after exposure to temperatures as high as 300 F for up to 1000 hrs. Microstructural changes were evaluated with thermal exposure in order to correlate with the observed data trends. The ambient temperature parent metal data showed an increase in strength and reduction in elongation after exposure at lower temperatures. Strength reached a peak with intermediate temperature exposure followed by a decrease at highest exposure temperature. Friction stir welds of all alloys showed a drop in elongation with increased length of exposure. Understanding the effect of thermal exposure on the properties and microstructure of Al-Li alloys must be considered in defining service limiting temperatures and exposure times for a reusable cryotank structure.

Shah, Sandeep↗
DOE OSTI2024

Effect of Si impurities on microstructure and tensile properties of a cast Al-Mg-Fe alloy

Al-Mg alloys are attractive for structural castings owing to their superior strength and ductility in the as-cast state. However, given the tight tolerance for impurities, Al-Mg alloys produced from secondary sources still face multiple challenges. Here, we report the effect of increased Si impurity (0.05–1.6 wt%), which is commonly found in secondary Al sources, on microstructure and tensile properties of a cast Al-4.3Mg-1.6Fe (wt%) alloy, commercially referred to as Castaduct-42 alloy. Microstructural characterization revealed that Si addition increased the volume fraction, size, and aspect ratio of primary Al13Fe4 intermetallic particles as well as the volume fraction of other binary and ternary eutectic phases. Tensile testing results demonstrated that increasing Si impurities from 0.05 to 1.6 wt% reduced ductility from 14.3 ± 1.4 % to 2.2 ± 1.0 %. A particle cracking damage accumulation model coupled with failure analysis indicated primary Al13Fe4 intermetallic particles to be the major contributing factor to the deterioration in ductility with increasing Si content. Additionally, the stabilizing effect of Si on primary Al 13 Fe 4 was inconsistent with the CALPHAD calculation results based on existing CALPHAD databases which predict a slightly decreasing primary Al13Fe4 phase fraction with increasing Si concentration. This work provides new insights into the phase stability and mechanical behavior of the lesser studied Al-Mg-Fe-Si alloy system that will contribute to the development of sustainable cast Al-Mg based alloys.

36 MATERIALS SCIENCE↗
NASA NTRS1989

Solution chemistry effects on the stress corrosion cracking behavior of alloy 2090 (Al-Li-Cu) and alloy 2024 (Al-Cu-Mg)

The SCC initiation behavior of alloys 2090 and 2024 is examined in various NaCl-based environments. The pre-exposure and bulk/local solution chemistry effects discovered by Holroyd et al. (1986) are investigated, with emphasis on the effect of bulk solution chemistries and atmospheric CO2 on the occluded cell environment and the role of the occluded environment in the crack initiation and early-stage propagation processes. It was found that constant immersion in NaCl does not promote SCC in alloy 2090 or alloy 2024. Upon removal from NaCl, SCC is quickly facilitated, but only in the presence of atmospheric CO2. The need for CO2 is attributed to an increase in carbonate concentrations, eventually allowing passivation of blunted fissures by precipitation of Li2CO3. It is inferred that any effects due to aging are small in magnitude, relative to the effects of subtle changes in the bulk/local solution chemistries.

Moran, James P.↗