Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “solidification”

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 1,207 records · Page 67
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Effect of growth parameters on compositional variations in directionally solidified HgCdTe alloys

A series of Hg(1-x)Cd(x)Te alloy crystals was grown by directional solidification with compositions ranging from x = 0.2 to x = 0.4. The measured axial compositional profiles were interpreted in terms of an exact numerical solution of the appropriate diffusion equation that takes into account both the variations of the segregation coefficient and solidification rate with composition. The solutions for all growth rates agree generally well with the experimental data, and confirm earlier observations that employed approximate analytical solutions. The effective mass diffusion coefficients showed no significant composition or melt temperature dependence. Slightly higher diffusion coefficients were obtained, however, for the highest growth rates.

Szofran, F. R.↗
NASA NTRS1985

Fluid Flow in Crystal Growth: Analysis of the Verticle Bridgman and Floating Zone Process

Research is aimed at the fundamental understanding of the interactions of heat and mass transport and fluid mechanics in crystal growth from the melt, especially in how it pertains to experiments supported by the Microgravity Science and Applications program. Emphasis has been on studies of the vertical Bridgman system, on small-scale floating zone systems proposed for space flight, and on quantitative prediction of nonlinear transitions in melt/solid interface morphologies leading to the formation of dendrites in directional solidification. The analysis of vertical Bridgman growth has lead to the complete numerical analysis of transport phenomena in directional solidification and to a detailed comparison of calculations to the GaGe growth experiments of Wang and Witt. Calculations show the central role of the ampoule material in determining the radial temperature gradients in the melt and thus, the intensity of convection. Results indicate that diffusion-controlled growth can not be achieved on Earth with conventional growth systems, but are feasible in microgravity

Brown, R. A.↗
NASA NTRS1985

The Influence of Containerless Undercooling and Rapid Solid-State Quenching on the Superconductive and Magnetic Properties of Some Clustering Alloy Systems

The potential of the 100-meter drop-tube for producing materials with new and important properties by their rapid solidification containerless undercooling was investigated. Materials produced exhibit evidence of very rapid quenching. The importance of rapid quenching in producing materials of considerable scientific and technological interest is emphasized. It is indicated that containerless undercooling, using at first a drop tube and eventually a space-shuttle-serviced orbiting laboratory, will provide another powerful approach for rapid quenching. A special advantage of the drop tube is that the microgravity condition is imposed ballistically; it is therefore possible to obtain either spherical samples by allowing solidification to take place in flight, or splats by allowing the sample material while still in undercooled liquid form to impact a stationary quench plate.

Collings, E. W.↗
NASA NTRS1985

Mephisto: Interfacial Destabilization in Metal Alloys

The destabilizing mechanisms at a solidification interface were studied to obtain information on the kinetics and morphologies in the transient and steady state, and to separate the influences of liquid phase instabilities from interfacial instabilities. A differential seebeck voltage measurements technique was developed to provide a continuous record of the solid-liquid interface temperature as the solidification rate is varied to determine the kinetic coefficients. Signal processing and noise suppression techniques allow nonovolt precision which corresponds to mK accuracy for the interfacial temperature.

Favier, J. J.↗
NASA NTRS1985

Orbital Processing of Aligned Magnetic Composites

Experiments will be conducted on the space shuttle in which aligned, two-phase magnetic composites will be grown by plane front directional solidification. The objectives are to: (1) identify and quantitatively evaluate the influences of gravitationally driven thermo-solutal convection on contained plane front solidification of binary, eutectic, off-eutectic, and peritectic magnetic composites; (2) to evaluate the effectiveness of micro-g processing as a means of damping convection; and (3) to evaluate the uniqueness of micro-g processing relative to the best of terrestrial convection damping.

Larson, D. J.↗
NASA NTRS1985

Containerless Processing of Undercooled Melts

The physical mechanisms controlling liquid undercooling were studied for application to solidification processing methods. The undercooling potential of containerless processing was assessed on droplet samples of high melting temperature metals drop tube and drop tower facilities and in a laboratory-scale apparatus. New insight into nucleation and crystal growth will be obtained in undercooled liquids of high melting temperature iron and nickel-base systems. The processing parameters include melt superheat, droplet size and particle statistics and droplet surface coating. The solidification behavior is determined by thermal analysis and by structural and metallographic characterization.

Perepezko, J. H.↗
NASA NTRS1985

Study on effects of powder and flake chemistry and morphology on the properties of Al-Cu-Mg-X-X-X powder metallurgy advanced aluminum alloys

The effects of alloy chemistry and particulate morphology on consolidation behavior and consolidated product properties in rapid solidification processed, powder-metallurgical Al-3Li-1.5Cu-1Mg-0.5Co-0.2Zr and Al-4.4Cu-1.5Mg-Fe-Ni-0.2Zr extrusions and forgings were studied. Microstructures and mechanical properties of both alloys are largely unaffected by particulate production method (vacuum atomization, ultrasonic atomization, or twin-roller quenching) and by particulate solidification rates between 1000 and 100,000 K/s. Consolidation processing by canning, cold compaction, degassing, and hot extrusion is sufficient to yield mechanical properties in the non-Li-containing alloy extrusions which are similar to those of 7075-Al, but ductilities and fracture toughnesses are inferior owing to poor interparticle bonding caused by lack of a vacuum-hot-pressing step during consolidation. Mechanical properties of extrusions are superior to those of forgings owing to the stronger textures produced by the more severe hot working during extrusion. The effects on mechanical properties of dispersoid size and volume fraction, substructural refinement, solid solution strengthening by Mg, and precipitate size and distribution are elucidated for both alloy types.

Meschter, P. J.↗
NASA NTRS1985

An advanced material science payload for GAS

The aim of the experiments is to study solidification phenomena in metal alloys. Especially the dendritic growth and the effect of the absence of natural convection are of particular interest for the scientist, professor Hasse Fredriksson at the Royal Institute of Technology (RIT) in Stockholm. The results from the flight processed samples will be compared with results from a lot of earth-processed samples in order to investigate the influence of the natural convection on the solidification process.

R. Jonsson↗
NASA NTRS1986

Space Processing Applications Rocket (SPAR) project: SPAR 10

The Space Processing Applications Rocket Project (SPAR) X Final Report contains the compilation of the post-flight reports from each of the Principal Investigators (PIs) on the four selected science payloads, in addition to the engineering report as documented by the Marshall Space Flight Center (MSFC). This combined effort also describes pertinent portions of ground-based research leading to the ultimate selection of the flight sample composition, including design, fabrication and testing, all of which are expected to contribute to an improved comprehension of materials processing in space. The SPAR project was coordinated and managed by MSFC as part of the Microgravity Science and Applications (MSA) program of the Office of Space Science and Applications (OSSA) of NASA Headquarters. This technical memorandum is directed entirely to the payload manifest flown in the tenth of a series of SPAR flights conducted at the White Sands Missile Range (WSMR) and includes the experiments entitled, Containerless Processing Technology, SPAR Experiment 76-20/3; Directional Solidification of Magnetic Composites, SPAR Experiment 76-22/3; Comparative Alloy Solidification, SPAR Experiment 76-36/3; and Foam Copper, SPAR Experiment 77-9/1R.

Poorman, R.↗
NASA NTRS1985

Measurement and analysis of distribution coefficients in Fe-Ni alloys containing S and/or P. II - K(Ir), K(Ge), and K(Cu)

Crystals of Fe-Ni-S-P alloys containing Ir, Ge, and Cu in small amounts were grown by plane front solidification. The electron microprobe was used to measure the compositions of these alloys. The Ir, Ge, and Cu distribution coefficients were determined by an analytical procedure from the composition data. The distribution coefficients of Ir, Ge, and Cu vary from 1.20 to 11.0, 0.75 to 2.1, and 0.06 to 0.84, respectively. K(Ir) and K(Ge) increase and K(Cu) decreases with the S content of the liquid. K(Cu) increases and K(Ir) and K(Ge) decrease with the P content of the liquid. Mathematical expressions have been formulated to relate the Ir, Ge, and Cu distribution coefficients to the S and P contents of the liquid. These distribution coefficients are important to the study of the solidification behavior of iron meteorites.

Sellamuthu, R.↗
NASA NTRS1986

Interaction of flows with the crystal-melt interface

The coupling between a crystal-melt interface and fluid flow is investigated. The solidification boundary conditions at the crystal-melt interface are described. The influences of morphological and double-diffusive instabilities during directional solidification on the interface are studied. The experiments by Glicksman and Mickalonis (1982) and Fang et al. (1985) which examine the relationship between the hydrodynamic state of the phase melt and phase-change interface are analyzed. The Rayleigh-Benard problem, and the effect of crystal-melt interaction on the Rayleigh number are examined. Various applications for melt-flow interactions with solid-liquid interface to engineering and welding are discussed.

Glicksman, M. E.↗
NASA NTRS1987

Growth of Metastable Peritectic Alloys

Effects of directional solidification on microstructural, compositional, and magnetic properties studied. Two reports describe experiments to determine effects of directional solidification on peritectic alloys. Of particular interest were effects of gravitationally driven convection.

Larson, David J., Jr.↗
NASA NTRS1986

Developmental testing of a programmable multizone furnace

A multizone furnace was evaluated for its potential utilization for process experimentation on board the Space Shuttle. A temperature gradient can be created through the use of a series of connected temperature zones and can be translated by the coordinated sequencing of zone temperatures. The Bridgman-Stockbarger thermal configuration for directional solidification was implemented so that neither the sample nor furnace was translated. The thermal behavior of the furnace was measured and characterized. Limitations due to both thermal and electronic (computer) factors are identified. The results indicate that the multizone design is limited to low temperature gradients because of the indirect furnace-to-sample thermal coupling needed to blend the discrete thermal zones. The multizone furnace design inherently consumes more power than a similar (two temperature) conventional Bridgman type directional solidification furnace because every zone must be capable of the high cooling rates needed to produce the maximum desired temperature drop. Typical achievable static temperature gradients for the furnace tested were between 6 and 75 C/in. The maximum gradient velocity was approximately 10 in./hr. Several aspects of the tested system could be improved, but the dependence of the multizone design on high heat loss will limit Space Shuttle applications in the form tested unless additional power is available. The multizone furnace offers great flexibility but requires a high level of operator understanding for full advantage to be obtained.

Ting, E. Y.↗
NASA NTRS1986

Activities of the Center for the Space Processing of Engineering Materials

Topics addressed include: containerless processing and purification; directional and rapid solidification; high temperature alloys; oxidation resistant niobium alloys; metallic bonding; effects of solidification mode on structure-property relationships; and dispersion strengthened metal alloys. Each of the projects is reported by company association and follow according to alphabetical order of the company names.

Source record↗
NASA NTRS1986

Processing-structure characterization of rheocast IN-100 superalloy

The rheocasting solidification process was applied in the production of IN-100 nickel base superalloy, and the effects of processing variables, such as stirring speed, isothermal stirring time, and volume fraction solid during isothermal stirring, on the resultant rheocast structure were investigated. Ingots that were furnace cooled at the same rate but without stirring were compared with the rheocast ingots. Rheocasting yielded fine-grained structures, where the extent of microsegregation, the variation in macrostructure, and the solidification-induced porosity and ingot cracking were found to be reduced in comparison to the unstirred ingots. The grain size and nonuniformity were reduced by increasing the stirring speed, isothermal stirring time, or the volume fraction solid during stirring; decreased microsegregation was achieved by an increase in the volume fraction solid. The structures of grain boundaries lent support to the grain boundary mechanism proposed by Vogel et al. (1977) for rheocasting.

Cheng, Jung-Jen Allen↗
NASA NTRS1986

Materials processing in space - Review of the early experiments

Basic research performed to study various aspects of fluid behavior in a microgravity environment during the first two decades of spaceflight is described. The uniqueness of space was recognized in the 1950s as a place where buoyancy-driven convective flows and sedimentation would effectively be absent. The conditions were favorable for experiments in crystal growth, alloy solidification, combustion, thermocapillary flows, electroosmotic flows, Stefan flows, Soret diffusion, and solidification processes. Pre-Skylab NASA drop tower experiments and Apollo 14 and 17 experiments made in preparation for Skylab are described. Skylab welding and brazing, crystal growth, metallurgy and liquid float zone trials and Apollo-Soyuz crystal growth, electrophoresis and metallurgical experiments are summarized. SPAR rocket trials along similar lines are also outlined.

Naumann, Robert J.↗
NASA NTRS1986

Microstructures in rapidly solidified Ni-Mo alloys

Ni-Mo alloys of compositions ranging from pure Ni to Ni-40 at. percent Mo were rapidly solidified by Chill Block Melt Spinning in vacuum and were examined by optical metallography, X-ray diffraction and transmission electron microscopy. Rapid solidification resulted in an extension of molybdenum solubility in nickel from 28 to 37.5 at. percent. A number of different phases and microstructures were seen at different depths (solidification conditions) from the quenched surface of the melt spun ribbons.

Jayaraman, N.↗
NASA NTRS1988

Transparent metal model study of the use of a cellular growth front to form aligned monotectic composite materials

The purpose of this work was to resolve a scientific controversy in the understanding of how second phase particles become aligned during unidirectional growth of a monotectic alloy. A second aspect was to make the first systematic observations of the solidification behavior of a monotectic alloy during cellular growth in-situ. This research provides the first systematic transparent model study of cellular solidification. An interface stability diagram was developed for the planar to cellular transition of the succinonitrile glycerol (SNG) system. A method was developed utilizing Fourier Transform Infrared Spectroscopy which allows quantitative compositional analysis of directionally solidified SNG along the growth axis. To determine the influence of cellular growth front on alignment for directionally solidified monotectic alloys, the planar and cellular growth morphology was observed in-situ for SNG between 8 and 17 percent glycerol and for a range of over two orders of magnitude G/R.

Kaukler, William F.↗