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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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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Analysis of gamma prime shape changes in a single crystal Ni-base superalloy

The microstructural evolution of a commercial single crystal superalloy, NASAIR 100, is analyzed using the existing high-temperature lattice mismatch data and high-temperature moduli obtained from tests on single crystals of gamma and gamma prime. A multiparticle analysis of the microstructural evolution is performed using a novel microstructural lattice simulation technique, MCFET. Under a uniaxial stress, a regular array of gamma prime particles in the simulated microstructure is predicted to coalesce and form a plate morphology, with the broad faces of the plates and stress axis perpendicular in tension but parallel in compression. These results are consistent with changes in gamma prime shape observed in NASAIR 100 following creep testing at 1000 C.

Gayda, J.↗
NASA NTRS1990

Ductility enhancement from interface dislocation sources in a directionally solidified beta + gamma + gamma-prime Ni-Fe-Al composite alloy

A directionally solidified beta + gamma + gamma-prime Ni-Fe-Al in situ composite alloy of composition Ni50Fe30Al20 has been used to investigate the effect of a plastically soft second phase on the mechanical behavior of a B2 ordered intermetallic alloy. This material exhibits extensive plasticity during compressive deformation at room temperature and fails in shear with extensive gamma + gamma-prime lamellar or rod pullout. The material also exhibits about 10 percent tensile elongation to fracture at room temperature, with final fracture that includes substantial necking of the gamma + gamma-prime lamellae or rods. Observation of slip lines and dislocation substructures discloses that the normally brittle beta matrix undergoes extensive plasticity in order to deform compatibly with the more ductile gamma phase. The plasticity of the beta matrix is accomplished by the generation of glissile dislocations into the beta matrix from the beta/gamma interface region and is enhanced because of a favorable beta-gamma orientation relationship for slip transfer. Ductility enhancement from interface-generated mobile dislocations generated from beta-gamma interfaces is compared to that observed in film-coated beta-NiAl single crystals and FeAl polycrystals.

Larsen, M.↗
NASA NTRS2012

The Gray Needle: Large Grains in the HD 15115 Debris Disk from LBT*/PISCES/K s and LBTIi+/LMIRcam/L(prime) Adaptive Optics Imaging

We present diffraction-limited K s band and L(prime) adaptive optics images of the edge-on debris disk around the nearby F2 star HD 15115, obtained with a single 8.4 m primary mirror at the Large Binocular Telescope. At the Ks band, the disk is detected at signal-to-noise per resolution element (SNRE) approx. 3-8 from approx. 1 to 2".5 (45-113 AU) on the western side and from approx. 1". 2 to 2".1 (63-90 AU) on the east. At L the disk is detected at SNRE approx. 2.5 from approx. 1 to 1".45 (45-90 AU) on both sides, implying more symmetric disk structure at 3.8 micrometers. At both wavelengths the disk has a bow-like shape and is offset from the star to the north by a few AU. A surface brightness asymmetry exists between the two sides of the disk at the Ks band, but not at L(prime). The surface brightness at the K s band declines inside 1"(approx. 45 AU), which may be indicative of a gap in the disk near 1".The K s − L(prime) disk color, after removal of the stellar color, is mostly gray for both sides of the disk. This suggests that scattered light is coming from large dust grains, with 3-10 micrometers sized grains on the east side and 1-10 micrometers dust grains on the west. This may suggest that the west side is composed of smaller dust grains than the east side, which would support the interpretation that the disk is being dynamically affected by interactions with the local interstellar medium.

signal-to-noise↗
NASA NTRS2008

Cassini-Huygens Maneuver Experience: Ending the Prime Mission

The Cassini-Huygens spacecraft was launched in 1997 on a mission to observe Saturn and its many moons. After a seven-year cruise, it entered a Saturnian orbit for a four-year, prime mission. This paper highlights significant maneuver activities performed during the last year of the prime mission. Specifically, results of 42 recent maneuvers are presented. Many maneuvers have been skipped, saving fuel and flight team effort. The system has performed more accurately than the pre-launch expectations and requirements. This is in large part why the Cassini-Huygens spacecraft has been navigated with tremendous success during the prime mission.

Saturn↗
NASA NTRS2018

Linear or Rotary Actuator Using Electromagnetic Driven Hammer as Prime Mover

We claim a hammer driven actuator that uses the fast-motion, low-force characteristics of an electro-magnetic or similar prime mover to develop kinetic energy that can be transformed via a friction interface to produce a higher-force, lower-speed linear or rotary actuator by using a hammering process to produce a series of individual steps. Such a system can be implemented using a voice-coil, electro-mechanical solenoid or similar prime mover. Where a typical actuator provides limited range of motion or low force, the range of motion of a linear or rotary impact driven motor can be configured to provide large displacements which are not limited by the characteristic dimensions of the prime mover.

Paine, Jeffrey S. N.↗
NASA NTRS2018

F Prime: An Open-Source Framework for Small-Scale Flight Software Systems

Developing flight software for small-scale missions such as CubeSats and SmallSats is challenging. These missions typically have ambitious goals, modest budgets, and tight schedules. To meet these challenges, a good flight software framework is essential. Frameworks can provide an architecture, infrastructure, tools, and reusable software components, all of which can help developers deliver their code on time and on budget. In this paper we present F Prime, a free, open-source flight software framework developed at JPL and tailored to small-scale systems such as CubeSats, SmallSats, and instruments. F Prime comprises several elements: (1) an architecture that decomposes flight software into discrete components with well-defined interfaces; (2) a C++ framework that provides core capabilities such as message queues and threads; (3) tools for specifying components and connections and automatically generating code; (4) a growing collection of ready-to-use components; and (5) tools for testing flight software at the unit and integration levels.We describe the F Prime framework and tools and present our experience using them. We describe several enhancements to the framework currently underway in the areas of software design, software verification, and ground data systems for testing.

Levison, Jeffrey W.↗
NASA NTRS2012

Development in High-Density Cobra Fiber Positioners for the Subaru Telescope's Prime Focus Spectrometer

The Prime Focus Spectrograph (PFS) is a fiber fed multi-object spectrometer for the Subaru Telescope that will conduct a variety of targeted surveys for studies of dark energy, galaxy evolution, and galactic archaeology. The key to the instrument is a high density array of fiber positioners placed at the prime focus of the Subaru Telescope. The system, nicknamed "Cobra", will be capable of rapidly reconfiguring the array of 2394 optical fibers to the image positions of astronomical targets in the focal plane with high accuracy. The system uses 2394 individual "SCARA robot" mechanisms that are 7.7mm in diameter and use 2 piezo-electric rotary motors to individually position each of the optical fibers within its patrol region. Testing demonstrates that the Cobra positioner can be moved to within 5 micrometers of an astronomical target in 6 move iterations with a success rate of 95%. The Cobra system is a key aspect of PFS that will enable its unprecedented combination of high-multiplex factor and observing efficiency on the Subaru telescope. The requirements, design, and prototyping efforts for the fiber positioner system for the PFS are described here as are the plans for modular construction, assembly, integration, functional testing, and performance validation.

Cobra↗
NASA NTRS1971

Heterogeneous nucleation of gamma prime in Al-Ag and Al-Ag /Cd or Cu/ alloys.

Results of transmission electron microscopy studies of heterogeneous nucleation of the metastable gamma prime phase were made in binary and ternary alloys of Al-5 at. % Ag, Al-4.8 at. % Ag-0.15 at. % Cd, and Al-4.8 at. % Ag-0.2 at. % Cu. Heterogeneous nucleation of gamma prime was found to be associated with four types of dislocations, regardless of the quenching treatment or alloy additions which were used. Nucleation was found to occur on: (a) jogged dislocations; (b) helical dislocations; (c) dislocation loops; (d) heterogeneous climb sources. Only one nucleation mechanism was found to be unique to the ternary alloys: that of nucleation on heterogeneous climb sources.

Passoja, D. E.↗
NASA NTRS1973

Eutectic superalloys strengthened by aligned delta, Ni3Cb lamellae, gamma-prime, Ni3Al precipitates and reduced interlamellar spacing.

Monovariant eutectic alloys, located on the liquidus trough between the binary eutectic gamma, Ni - delta, Ni3Cb and the ternary eutectic gamma, Ni - gamma-prime, Ni3Al - delta, Ni3Cb, were identified which permitted the production of aligned lamellae within a nickel solid solution matrix containing the precipitate gamma-prime. These alloys exhibited great insensitivity in their composite microstructures to solidification parameters such as growth rate temperature gradient, and were found to be remarkably uniform in composition along their length.

Lemkey, F. D.↗
NASA NTRS1974

The gamma-gamma prime region of the Ni-Al-Cr-Ti-W-Mo system at 850 C

The compositional limits of gamma and gamma-prime phases in nickel-base superalloys are determined experimentally. It is found that gamma-prime had the following range of compositions for the various elements contained in this phase: 72.1 to 78.0 at.% Ni; 7.8 to 17.3 at.% Al; 1.5 to 8.9 at.% Cr; 0.3 to 13.9 at.% Ti, 0.0 to 3.9 at.% Mo, and 0.0 to 7.2 at.% W. The composition of gamma varied as follows: Ni is balanced; 1.9 to 15.4 at.% Al; 6.6 to 30.7 at.% Cr; 0.0 to 3.1 at.% Ti; 0.0 to 8.7 at.% Mo; and 0.0 to 5.0 at.% W. W additions to the gamma appeared to increase somewhat the solubility of Al in this phase. Mo and W added together decreased the solubility of Al in gamma.

Dreshfield, R. L.↗
NASA NTRS1975

Resistance of a gamma/gamma prime - delta directionally solidified eutectic alloy to recrystallization

The lamellar directionally solidified nickel-base eutectic alloy gamma/gamma prime-delta has potential as an advanced turbine blade material. The microstructural stability of this alloy was investigated. Specimens were plastically deformed by uniform compression or Brinell indentation, then annealed between 705 and 1120 C. Microstructural changes observed after annealing included gamma prime coarsening, pinch-off and spheroidization of delta lamellae, and the appearance of an unidentified blocky phase in surface layers. All but the first of these was localized in severely deformed regions, suggesting that microstructural instability is not a serious problem in the use of this alloy.

Tewari, S. N.↗
NASA NTRS1976

Heat treating of a lamellar eutectic alloy /gamma/gamma prime + delta/

Eutectic superalloys are being developed at several laboratories for application as aircraft gas turbine airfoils. One such alloy gamma/gamma prime + delta was subjected to several heat treatments to determine if its mechanical properties could be improved. It was found that by partially dissolving the gamma prime at 1210 C and then aging at 900 C, the tensile strength can be increased about 12 per cent at temperatures up to 900 C. At 1040 C, no change in tensile strength was observed. Times to rupture were measured between 760 and 1040 C and were essentially the same or greater than for as-grown material. Tensile and rupture ductility of the alloy were reduced by heat treatment.

Tewari, S. N.↗
NASA NTRS1976

Resistance of a directionally solidified gamma/gamma prime-delta eutectic alloy to recrystallization

A lamellar nickel-base directionally-solidified eutectic gamma/gamma prime-delta alloy has potential as an advanced gas turbine blade material. The microstructural stability of this alloy was investigated. Specimens were plastically deformed by uniform compression or Brinell indentation, then annealed between 750 and 1120 C. Microstructural changes observed after annealing included gamma prime coarsening, pinch-off and spheroidization of delta lamellae, and appearance of an unidentified blocky phase in surface layers. All but the first of these was localized in severely deformed regions, suggesting that microstructural instability may not be a serious problem in the use of this alloy.

Tewari, S. N.↗
NASA NTRS1977

Diffusion welding of a directionally solidified gamma/gamma prime - delta eutectic alloy

Hot-press diffusion welding parameters were developed for a directionally solidified, gamma/gamma prime-delta eutectic alloy. Based on metallography, a good diffusion weld was achieved at 1100 C under 34.5 MPa (5 ksi) pressure for 1 hour. In addition, a dissimilar metal weld between gamma/gamma prime-delta and IN-100 was successfully made at 1100 C under 20.7 MPa (3 ksi) pressure for 1 hour.

Moore, T. J.↗
NASA NTRS1977

The prime meridian of Mars and the longitudes of the Viking landers

A planetwide control net of Mars has been computed by a single large-block analytical triangulation derived from 17,224 measurements of 3,037 control points on 928 Mariner 9 pictures. The computation incorporated the Viking-determined direction of the spin axis and rotation rate of Mars. The angle measured from the vernal equinox to the prime meridian (areocentric right ascension) of Mars was determined to be 148.368 deg + 350.891986 deg (JD - 2433282.5), where JD refers to the Julian date. The prime meridian of Mars passes through the center of the small crater Airy-O. The longitudes of the Viking landers are 47.82 + or - 0.1 deg for Lander 1 and 225.59 + or - 0.1 deg for Lander 2.

Davies, M. E.↗
NASA NTRS1977

Pressureless sintered beta prime-Si3N4 solid solution: Fabrication, microstructure, and strength

Si3N4, AlN, and Al2O3 were used as basic constituents in a study of the pressureless sintering of beta prime-Si3N4 solid solution as a function of temperature. Y2O3-SiO2 additions were used to promote liquid-phase sintering. The sintered specimens were characterized with respect to density, microstructure, strength, oxidation, and thermal shock resistance. Density greater than 98 percent of theoretical was achieved by pressureless sintering at 1750 C. The microstructure consisted essentially of fine-grained beta prime-Si3N4 solid solution as the major phase. Modulus of rupture strengths up to 483 MPa were achieved at moderate temperature (1000 C), but decreased to 228 MPa at 1380 C. This substantial strength loss was attributed to a glassy grain boundary phase formed during cooling from the sintering temperature. The best oxidation resistance was exhibited by a composition containing 3 mol % Y2O3-SiO2 additives. Water quench thermal shock resistance was equivalent to that of reaction sintered silicon nitride but lower than hot-pressed silicon nitride.

Dutta, S.↗
NASA NTRS1977

Pressureless sintered beta-prime-Si3N4 solid solution - Fabrication, microstructure, and strength

Pressureless sintering of beta-prime-Si3N4 solid solution was studied as a function of temperature using Si3N4, A1N, and Al2O3 as basic constituents. Y2O3-SiO2 additions were used to promote liquid-phase sintering. The sintered specimens were characterized with respect to density, microstructure, strength, oxidation, and thermal shock resistance. Density greater than 98 percent of theoretical was achieved by pressureless sintering at 1750 C. The microstructure consisted essentially of fine-grained beta-prime-Si3N4 solid solution as the major phase. Modulus of rupture strengths up to 483 M Pa were achieved at moderate temperature (1000 C), but decreased to 228 M Pa at 1380 C. This substantial strength loss was attributed to a 'glassy' grain boundary phase formed during cooling from the sintering temperature. The best oxidation resistance was exhibited by a composition containing 3 mol % Y2O3-SiO2 additives. Water quench thermal shock resistance was equivalent to that of reaction sintered silicon nitride but lower than hot-pressed silicon nitride.

Dutta, S.↗
NASA NTRS1979

Spatially resolved infrared observations of Saturn. III - 10- and 20-micron disk scans at B prime = -11.8 deg

Disk scans of Saturn at 10 and 20 microns were obtained when the Saturnicentric solar declination B prime was -11.8 deg. The scans show little change from scans obtained when B prime was -16.3 deg. This could result from the long radiative time constant of the Saturnian atmosphere. The observations at 20 microns, in the H2 continuum, show positively that the temperature inversion at the south pole has a higher temperature than at any other point on the disk. In addition, the 12.1- and 20-micron scans indicate that the temperature of the inversion region is higher at the equator compared to the temperate zone. The data also suggest that enhanced 20-micron emission is correlated with the strength of the ultraviolet absorption.

Tokunaga, A. T.↗