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  • Other Sources  (189)
  • METALLIC MATERIALS  (189)
  • 2015-2019
  • 1980-1984  (189)
  • 1940-1944
  • 1
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    Long-term high-velocity oxidation and hot corrosion testing of several NiCrAl and FeCrAl base oxide dispersion strengthened alloys (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Several oxide dispersion strengthened (ODS) alloys have been tested for cyclic, long-term, high gas-velocity resistance to oxidation at 1100 C and hot corrosion at 900 C. Both nominally Ni-16Cr-4Al and Fe-20Cr-4.5Al ODS alloys were subjected up to about 2500 cycles, where each cycle consisted of 1 hr in a hot, Mach 0.3 combusted gas stream followed by a 3-min quench in an ambient temperature, Mach 0.3 air blast. For comparison to existing technology, a coated superalloy was simultaneously tested. The ODS iron alloy exhibited clearly superior behavior, surviving 3800 oxidation and 2300 hot corrosion cycles essentially unscathed. While the ODS nickel alloys exhibited adequate oxidation resistance, the long-term hot corrosion resistance could be marginal, since the best life for such alloys under these conditions was only about 1100 cycles. However, the hot corrosion resistance of the ODS Ni-base alloys is excellent in comparison to that of traditional superalloys.
    Keywords: METALLIC MATERIALS
    Type: Oxidation of Metals; 17; Apr. 198
    Format: text
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  • 2
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    Hot isostatically pressed manufacture of high strength MERL 76 disk and seal shapes (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The feasibility of using MERL 76, an advanced high strength direct hot isostatic pressed powder metallurgy superalloy, as a full scale component in a high technology, long life, commercial turbine engine were demonstrated. The component was a JT9D first stage turbine disk. The JT9D disk rim temperature capability was increased by at least 22 C and the weight of JT9D high pressure turbine rotating components was reduced by at least 35 pounds by replacement of forged Superwaspaloy components with hot isostatic pressed (HIP) MERL 76 components. The process control plan and acceptance criteria for manufacture of MERL 76 HIP consolidated components were generated. Disk components were manufactured for spin/burst rig test, experimental engine tests, and design data generation, which established lower design properties including tensile, stress-rupture, 0.2% creep and notched (Kt = 2.5) low cycle fatigue properties, Sonntag, fatigue crack propagation, and low cycle fatigue crack threshold data. Direct HIP MERL 76, when compared to conventionally forged Superwaspaloy, is demonstrated to be superior in mechanical properties, increased rim temperature capability, reduced component weight, and reduced material cost by at least 30% based on 1980 costs.
    Keywords: METALLIC MATERIALS
    Type: NASA-CR-165549 , NAS 1.26:165549 , PWA/5574-123
    Format: application/pdf
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  • 3
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    Development of improved high temperature coatings for IN-792 + HF (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The development for t-55 l712 engine of high temperature for integral turbine nozzles with improved thermal fatigue resistance without sacrificing oxidation/corrosion protection is discussed. The program evaluated to coating systems which comprised one baseline plasma spray coating (12% Al-NiCoCrALY), three aluminide coatings including the baseline aluminide (701), two CoNiCrAly (6% Al) + aluminide systems and four NiCoCrY + aluminide coating were evaluated. The two-step coating processes were investigated since it offered the advantage of tailoring the composition as well as properly coating surfaces of an integral or segmented nozzle. Cyclic burner rig thermal fatigue and oxidation/corrosion tests were used to evaluate the candidate coating systems. The plasma sprayed 12% Al-NiCoCrAlY was rated the best coating in thermal fatigue resistance and outperformed all coatings by a factor between 1.4 to 2.5 in cycles to crack initiation. However, this coatings is not applicable to integral or segmented nozzles due to the line of sight limitation of the plasma spray process. The 6% Al-CoNiCrAlY + Mod. 701 aluminide (32 w/o Al) was rated the best coating in oxidation/corrosion resistance and was rated the second best in thermal fatigue resistance.
    Keywords: METALLIC MATERIALS
    Type: NASA-CR-165395
    Format: application/pdf
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  • 4
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    Development of a high strength hot isostatically pressed /HIP/ disk alloy, MERL 76 (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A nickel-based powder metal disk alloy developed for use in advanced commercial gas turbines is described. Consideration is given to final alloy chemistry modifications made to achieve a desirable balance between tensile strength and stress rupture life and ductility. The effects of post-consolidation heat treatment are discussed, the preliminary mechanical properties obtained from full-scale turbine disks are presented.
    Keywords: METALLIC MATERIALS
    Type: International Powder Metallurgy Conference and Exhibition; Jun 22, 1980 - Jun 27, 1980; Washington, DC
    Format: text
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  • 5
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    NBS: Nondestructive evaluation of nonuniformities in 2219 aluminum alloy plate: Relationship to processing (1980)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The compositional homogeneity, microstructure, hardness, electrical conductivity and mechanical properties of 2219 aluminum alloy plates are influenced by the process variables during casting, rolling and thermomechanical treatment. The details of these relationships wre investigated for correctly processed 2219 plate as well as for deviations caused by improper quenching after solution heat treatment. Primary emphasis was been placed on the reliability of eddy current electrical conductivity and hardness as NDE tools to detect variations in mechanical properties.
    Keywords: METALLIC MATERIALS
    Type: NASA-CR-164596 , PB81-172348 , NBSIR-80-2069
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  • 6
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    Advances in metals processing (1982)
    In:  CASI
    Details
    Publication Date: 2006-04-12
    Description: Research on metals processing being conducted to develop improved forming and joining methods with the potential of reducing the weight and cost of future aerospace structures is discussed. The approach followed is to assess the state of the art for fabricating a given structural system, define candidate methods for improving processing, evaluate the merits of each, fabricate and test subelement components, and then scale up the process to demonstrate validity. The development and the state of the art of weldbrazing, superplastic forming (SPF), superplastic forming and codiffusion bonding and superplastic forming and weldbrazing for titanium and the SPF of aluminum is discussed.
    Keywords: METALLIC MATERIALS
    Type: Advan. Mater. Technol.; p 201-218
    Format: text
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  • 7
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    Macrosegregation in aluminum alloy ingot cast by the semicontinuous direct chill method (1984)
    In:  CASI
    Details
    Publication Date: 2006-06-08
    Description: A theoretical model of the semicontinuous DC casting method is developed to predict the positive segregation observed at the subsurface and the negative segregation commonly found at the center of large commercial-size aluminum alloy ingot. Qualitative analysis of commercial-size aluminum alloy semicontinuous cast direct chill (DC) ingot is carried out. In the analysis, both positive segregation in the ingot subsurface and negative segregation at the center of the ingot are examined. Ingot subsurface macrosegregation is investigated by considering steady state casting of a circular cross-section binary alloy ingot. Nonequilibrium solidification is assumed with no solid diffusion, constant equilibrium partition ratio, and constant solid density.
    Keywords: METALLIC MATERIALS
    Type: NASA. Lewis Research Center Fundamentals of Alloy Solidification Appl. to Industrial Processes; p 157-168
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  • 8
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    Characterization of macrosegregation in ESR IN-718 (1984)
    In:  CASI
    Details
    Publication Date: 2006-06-08
    Description: Aspects of macrosegregation theory, such as dendrite arm spacing, pool profile and mushy zone depth are beneficial to developing consumable melting process for Ion Nickel IN-718, Electro-Slag Refining, especially ESR. Aspects of microsegregation theory, such as correlation of dendrite arm spacing with heat transfer mechanisms and local solidification time, are used to minimize remnant dendritism in both ESR and Vacuum Arc Remelting VAR IN-718. Specifically, ESR IN-718 must be optimized by developing practices which maximize ingot cooling rate and minimize the steepness of the solidus and liquidus isotherms. The knowledge concerning macrosegregation in consumable melted IN-718 is in the form of correlations. Since the isotherm steepness is undoubtedly involved, investigations which include a microgravity environment might separate microsegregation effects from macrosegregation effects. Accounting for the effects of gravity and density differences between the metal pool and the interdendritic fluid, in combination with the pool and mushy zone profiles, can lead to improved melting solidification practices for IN-718, and allow prediction of macrosegregation tendency to be incorporated into high temperature alloy design.
    Keywords: METALLIC MATERIALS
    Type: NASA. Lewis Research Center Fundamentals of Alloy Solidification Appl. to Industrial Processes; p 139-150
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  • 9
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    The undercooling of liquids (1984)
    In:  CASI
    Details
    Publication Date: 2006-06-08
    Description: The formation by melt quenching of such metastable structures as glassy or microcrystalline solids and highly supersaturated solutions is made possible by the extreme resistance of most melts to homophase crystal nucleation at deep undercooling. This nucleation resistance contrasts sharply with the very low kinetic resistance to the movement of crystal-melt interfaces, once formed, in metals and other fluid systems at even minute undercooling. The methods of nucleation study which have proven especially effective in bypassing nucleation by heterophase impurities thereby exposing the high resistance of melts to homophase nucleation may be summarized as follows: observation of the crystallization behavior of dispersed small droplets; drop tube experiments in which liquid drops solidify, under containerless conditions, during their fall in the tube; and observation of the crystallization of bulk specimens immersed in fluxes chosen to dissolve or otherwise deactivate (e.g., by wetting) heterophase nucleants. This method has proven to be remarkably effective in deactivating such nucleants in certain pure metals.
    Keywords: METALLIC MATERIALS
    Type: NASA. Lewis Research Center Fundamentals of Alloy Solidification Appl. to Industrial Processes; p 11-14
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  • 10
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    Nature of gamma-prime precipitates in rheocast IN-100 alloy (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The microstructures of commercial VIM-cast and rheocast (Apelian and Cheng, 1983) IN-100 superalloy are investigated optically and by two-stage replica TEM, with an emphasis on the nature of the gamma-prime (GP) precipitates. Photomicrographs at magnifications of 39, 390, 2145, and 6630 are presented and discussed. VIM-cast IN-100 has dendritic structure, 10-20-micron primary GP particles, and uniformly distributed cuboid GP precipitates of a uniform size (about 0.5 micron). Rheocast IN-100 (stirred 20 min at 350 rpm, 1291 C, and 0.0006 torr) has a nondendritic structure, 20-100-micron primary GP particles, and a smaller volume fraction of cuboid GP precipitates with a bimodal (either 1-1.5 microns or less than 0.5 micron) size distribution. Such distribution should increase fatigue-crack-nucleation resistance.
    Keywords: METALLIC MATERIALS
    Type: Journal of Materials Science Letters (ISSN 0261-8028); 3; 71-73
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