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  • 1
    facet.materialart.
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    Metal powder production by gas atomization (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The confined liquid, gas-atomization process was investigated. Results from a two-dimensional water model showed the importance of atomization pressure, as well as delivery tube and atomizer design. The atomization process at the tip of the delivery tube was photographed. Results from the atomization of a modified 7075 aluminum alloy yielded up to 60 wt pct. powders that were finer than 45 microns in diameter. Two different atomizer designs were evaluated. The amount of fine powders produced was correlated to a calculated gas-power term. An optimal gas-power value existed for maximized fine powder production. Atomization at gas-power greater than or less than this optimal value produced coarser powders.
    Keywords: METALLIC MATERIALS
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  • 2
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    The structure and properties of rapidly solidified high alloy aluminum materials (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A series of 2024 type aluminum alloys modified by additions of 1 to 2% Li were studied to determine the role of the Cu:Li and the (Cu + Mg):Li ratios on resultant strength, ductility, notch-tensile behavior, and crack propagation rates. Ultrasonically gas atomized powders with quench rates of 10 to 100 thousand degrees/s were atomized in an argon atmosphere, producing yields of powder such that almost 100% was finer than 250 microns. The powders are free of gases and porosity, are quite spherical, have few satellites (adhering fine powder particles) and are of uniform microstructure. Strength properties are such that yield strength is 20% greater than for lithium-free 2024 ingot alloy, tensile strength is 10% greater than that of 2024 ingot material, and ductilities are comparable. In terms of specific strength and specific modulus, these RS 2024-Li alloys are significantly better than IM 2024.
    Keywords: METALLIC MATERIALS
    Type: The Mater. Process. Res. Base of the Mater. Process. Center 73-78 (SEE N82-27382 18-23)
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  • 3
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    Rapid solidification of metallic particulates (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: In order to maximize the heat transfer coefficient the most important variable in rapid solidification is the powder particle size. The finer the particle size, the higher the solidification rate. Efforts to decrease the particle size diameter offer the greatest payoff in attained quench rate. The velocity of the liquid droplet in the atmosphere is the second most important variable. Unfortunately the choices of gas atmospheres are sharply limited both because of conductivity and cost. Nitrogen and argon stand out as the preferred gases, nitrogen where reactions are unimportant and argon where reaction with nitrogen may be important. In gas atomization, helium offers up to an order of magnitude increase in solidification rate over argon and nitrogen. By contrast, atomization in vacuum drops the quench rate several orders of magnitude.
    Keywords: METALLIC MATERIALS
    Type: NASA-CR-169070 , NAS 1.26:169070
    Format: application/pdf
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  • 4
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    Powder and particulate production of metallic alloys (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Developments of particulate metallurgy of alloyed materials where the final products is a fully dense body are discussed. Particulates are defined as powders, flakes, foils, silvers, ribbons and strip. Because rapid solidification is an important factor in particulate metallurgy, all of the particulates must have at least one dimension which is very fine, sometimes as fine as 10 to 50 microns, but move typically up to several hundred microns, provided that the dimension permits a minimum solidification rate of at least 100 K/s.
    Keywords: METALLIC MATERIALS
    Type: NASA-CR-169069 , NAS 1.26:169069
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  • 5
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    Structure-property relationships in thermomechanically treated beryllia dispersed nickel alloys (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: BeO dispersed nickel alloys, produced by powder metallurgy techniques, were studied extensively in stress rupture at 815, 982, and 1093 C (1088, 1255, and 1366 K) and by transmission electron microscopy. The alloys were subjected to a variety of thermomechanical treatments (TMT) to determine the benefits of TMT on properties. It is shown that the use of intermediate annealing treatments after 10 pct reduction steps is highly beneficial on both low and high temperature properties. It is indicated that the high temperature strength is not primarily dependent on the grain aspect ratio or texture but depends strongly on the dislocation density and distribution of dislocations in a stable substructure which is pinned by the fine oxide dispersion.
    Keywords: METALLIC MATERIALS
    Type: Metallurgical Transactions A - Physical Metallurgy and Materials Science; 6A; July 197
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  • 6
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    Properties of splat-quenched 7075 aluminum type alloys (1976)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The 7075 alloy belonging to the Al-Zn-Mg-Cu system, prepared by powder metallurgy techniques, was used in a study of alloys prepared from splat-quenched foils consolidated into bar material by hot extrusion. Ni and Fe were included in one alloy specimen, producing a fine dispersion of FeAl3 type particles which added to the strength of the aged alloy but did not coarsen upon heat treatment. Fine oxide films showing up on air-splatted foils induce finely dispersed oxide stringers (if the foils are not hot-worked subsequently) which in turn promote axial cracking (but longitudinal tensile strength is not seriously impaired). Splatting in a protective atmosphere, or thermomechanical processing, is recommended to compensate for this.
    Keywords: METALLIC MATERIALS
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  • 7
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    Precipitation of silicon from splat-cooled Al-Si alloys (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Splat cooled Al-Si solid solutions with 1 to 11 at.% Si were prepared and their precipitation kinetics were studied by transmission electron microscopy. The time required for appearance of particles visible at a magnification of 35,000 times was determined at temperatures between 248 K and 573 K. The resulting Arrhenius plots yielded activation energies ranging from 55 to 40 plus or minus 2kJ/mol over the composition range. Precipitate densities were higher and denuded zones of 100 to 150 nm were narrower than in comparable solid quenched samples. The activation energies are explained in terms of excess point defect concentrations.
    Keywords: METALLIC MATERIALS
    Type: Metallurgical Transactions A - Physical Metallurgy and Materials Science; 6A; Dec. 197
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  • 8
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    Applications of metastable microcrystalline alloys (1978)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The mechanical properties of rapidly quenched superalloys, aluminum alloys, stainless steels, and titanium alloys are briefly reviewed. Studies on the materials are mentioned, and the superplasticity properties of the alloys are highlighted.
    Keywords: METALLIC MATERIALS
    Type: Rapidly quenched metals III; Third International Conference; Jul 03, 1978 - Jul 07, 1978; Brighton
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  • 9
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    Rapid solidification of metallic particulates (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: In order to maximize the heat transfer coefficient the most important variable in rapid solidification is the powder particle size. The finer the particle size, the higher the solidification rate. Efforts to decrease the particle size diameter offer the greatest payoff in attained quench rate. The velocity of the liquid droplet in the atmosphere is the second most important variable. Unfortunately the choices of gas atmospheres are sharply limited both because of conductivity and cost. Nitrogen and argon stand out as the preferred gases, nitrogen where reactions are unimportant and argon where reaction with nitrogen may be important. In gas atomization, helium offers up to an order of magnitude increase in solidification rate over argon and nitrogen. By contrast, atomization in vacuum drops the quench rate several orders of magnitude. Previously announced in STAR as N82-26433
    Keywords: METALLIC MATERIALS
    Type: High-strength powder metallurgy aluminum alloys; Proceedings of the Symposium, Dallas; Jan 17, 1982 - Jan 18, 1982; Dallas, TX
    Format: text
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