938 Matching Results

Search Results

Advanced search parameters have been applied.
in subjects: "Grain Boundaries"  
Results: 1 - 24 next
open access

Radiation-induced segregation in HT-9 martensitic steel

Description: Miniature notched-bar specimens of normalized and tempered HT-9 were neutron irradiated to approx.13 dpa and broken at liquid nitrogen temperatures in a UHV chamber. Fracture surfaces were analyzed using scanning Auger electron spectroscopy. Following irradiation at 410/sup 0/C, the fracture surface contained a small number of large relatively smooth facets, which are thought to be prior austenite grain boundaries. Strong segregation of Ni, Cr, Si, and P was detected at these surfaces, the rema… more
Date: January 1, 1986
Creator: Clausing, R.E.; Heatherly, L.; Faulkner, R.G.; Rowcliffe, A.F. & Farrell, K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Mechanism for Diffusion Induced Grain Boundary Migration

Description: Grain boundaries are found to migrate under certain conditions when solute atoms are diffused along them. This phenomenon, termed diffusion induced grain boundary migration (DIGM), has now been found in six systems. The observed phenomenon and empirical data are used to discard certain concepts for the driving force and the mechanism. A mechanism is proposed in which differences in the diffusion coefficients of the diffusing species along the grain boundary cause a self-sustaining climb of grai… more
Date: August 1, 1980
Creator: Balluffi, R. W. & Cahn, J. W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Creep Rupture in the Presence of a Fast Neutron Flux

Description: Possible mechanisms for creep rupture during irradiation are examined. Evidence that the rupture occurs by grain boundary sliding alone, or by vacancy condensation, is compared. It is observed that vacancy condensation is the more probable mechanism, and that this mechanism predicts a reduction in creep rupture life for metals exposed to a fast neutron flux (neglecting effects of radiation annealing). (T.F.H.)
Date: January 14, 1959
Creator: Gregory, D. P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Volume dependence of computed grain boundary energy

Description: Over the past five years there have been numerous studies of grain boundary structure using the method of computer molecular statics which assume pairwise central potentials for the interatomic interaction. Emphasis is usually placed on relative grain boundary energies but these may be inaccurate due to various, but related, approximations and constraints implicity imposed on the calculation-namely central forces, finite model size, fixed border conditions and volume dependent contributions to … more
Date: August 1, 1980
Creator: Bristowe, P.D. & Brokman, A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Scale effects in sliding friction: An experimental study

Description: Solid friction is considered by some to be a fundamental property of two contacting materials, while others consider it to be a property of the larger tribosystem in which the materials are contained. A set of sliding friction experiments were designed to investigate the hypothesis that the unlubricated sliding friction between two materials is indeed a tribosystems-related property and that the relative influence of the materials properties or those of the machine on friction varies from one s… more
Date: July 24, 1991
Creator: Blau, P.J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Ir/PuO/sub 2/ compatibility: transfer of impurities from plutonium dioxide to iridium metal during high temperature aging

Description: Plutonium oxide fuel pellets for powering radioisotopic thermoelectric generators for NASA space vehicles are encapsulated in iridium which has been grain-boundary-stabilized with thorium and aluminum. After aging for 6 months at 1310/sup 0/C under vacuum, enhanced grain growth is observed in the near-surface grains of the iridium next to the PuO/sub 2/. Examination of the grain boundaries by AES and SIMS shows a depletion of thorium and aluminum. Iron, chromium, and nickel from the fuel were f… more
Date: January 1, 1984
Creator: Taylor, D. H.; Christie, W. H. & Pavone, D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Silicon materials task of the Low-Cost Solar Array Project (Phase IV). Effects of impurities and processing on silicon solar cells. Nineteenth quarterly report, April 1980-June 1980

Description: The overall objective of this program is to define the effects of impurities, various thermochemical processes, and any impurity-process interactions upon the performance of terrestrial solar cells. The results of the study form a basis for silicon producers, wafer manufacturers, and cell fabricators to develop appropriate cost-benefit relationships for the use of less pure, less costly solar grade silicon. Nine 4 ohm-cm p type silicon ingots were grown and evaluated in support of the experimen… more
Date: July 1, 1980
Creator: Hopkins, R. H.; Davis, J. R.; Rohatgi, A.; Campbell, R. B.; Rai-Choudhury, P.; Hanes, M. H. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Design, microstructure, and high-temperature behavior of silicon nitride sintered with rate-earth oxides

Description: The processing-microstructure-property relations of silicon nitride ceramics sintered with rare-earth oxide additives have been investigated with the aim of improving their high-temperature behavior. The additions of the oxides of Y, Sm, Gd, Dy, Er, or Yb were compositionally controlled to tailor the intergranular phase. The resulting microstructure consisted of {beta}-Si{sub 3}N{sub 4} grains and a crystalline secondary phase of RE{sub 2}Si{sub 2}O{sub 7}, with a thin residual amorphous phase … more
Date: August 1, 1991
Creator: Ciniculk, M.K. (California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering)
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Electronic properties of silicon grain boundaries

Description: Polycrystalline silicon is a clean and relatively simple prototype of electronic ceramics. The theory of the electrostatic barriers which form at silicon grain boundaries will be discussed. The use of experimental conductance and capacitance measurements to obtain the barrier height and energy density of grain boundary states will be illustrated.
Date: January 1, 1980
Creator: Pike, G. E. & Seager, C. H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Investigation of the impurity tolerance of semicrystalline silicon solar cells silicon impact program. Quarterly technical progress report No. 2, January 1, 1980-March 31, 1980

Description: Design modifications were made to incorporate thermocouples into the polysilicon casting furnace to allow for the constant monitoring of the temperature profile during the casting process. A source of metallurgical grade (MG) silicon was chosen and the material was prepared by grinding the large pieces into powder. The uniformity of the feedstock was ascertained by optical emission spectrograph analysis of three random samples of the feedstock. A total of sixteen casting runs were made this qua… more
Date: January 1, 1980
Creator: Storti, G.; Regnault, W.; Johnson, S.; Lin, H. C. & Armstrong, R. W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Thin film polycrystalline silicon solar cells

Description: During the present quarter efficiency of heterostructure solar cells has been increased from 13 to 13.7% for single crystal and from 10.3 to 11.2% for polysilicon. For polysilicon the improvements can be attributed to reductions in grid-area coverage and in reflection losses and for single crystal to a combination of reduction in grid-area coverage and increase in fill factor. The heterostructure cells in both cases were IT0/n-Si solar cells. Degradation in Sn0/sub 2//n-Si solar cells can be gr… more
Date: January 1, 1980
Creator: Ghosh, A. K.; Feng, T.; Eustace, D. J. & Maruska, H. P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Investigation of photovoltaic mechanisms in polycrystalline thin-film solar cells. Interim technical report, November 1, 1980-July 31, 1981

Description: Effort is reported on measurement technique development to assess the utility of Deep-Level Transient Spectroscopy (DLTS) methods in characterizing polycrystalline silicon that was deliberately doped with Ti during growth. Difficulties encountered with lateral DLTS measurements are discussed. In this approach, modulation of the grain boundary, double-depletion region produces the entire DLTS signal. Major effort has been applied in grain boundary characterization and control. The most significa… more
Date: March 5, 1982
Creator: Temofonte, T. A.; Szedon, J. R. & O'Keeffe, T. W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Thin films of gallium arsenide on low-cost substrates. Quarterly technical progress report No. 6 and topical report No. 2, January 1, 1978-April 1, 1978

Description: The metalorganic chemical vapor deposition (MO-CVD) technique has been applied to the growth of thin films of GaAs and GaAlAs on inexpensive polycrystalline or amorphous substrate materials (primarily glasses and metals) for use in fabrication of large-area low-cost photovoltaic device structures. Trimethylgallium (TMG), arsine (AsH/sub 3/), and trimethylaluminum (TMAl) are mixed in appropriate concentrations at room temperature in the gaseous state and pyrolyzed at the substrate, which is heat… more
Date: April 1, 1978
Creator: Ruth, R. P.; Dapkus, P. D.; Dupuis, R. D.; Campbell, A. G.; Johnson, R. E.; Manasevit, H. M. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Fabrication and characterization of ITO/silicon SIS solar cells. Final report, October 1, 1978-April 30, 1980

Description: The objectives of this research were to optimize the performance of ITO/polycrystalline silicon solar cells, identify performance limitations, identify major stability problems which would inhibit terrestrial application of these devices, evaluate the impact of indium supply and price on terrestrial applications, and evaluate the economic viability of ITO sputter deposited solar cells. These goals were successfully achieved during the course of this multipronged effort. Both area scaling with e… more
Date: June 1, 1980
Creator: DuBow, J. B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Study of grain boundary segregation using the Auger electron emission technique. Annual Technical Progress Report January 1, 1979-December 31, 1979

Description: The influence of grain boundary chemical composition on hydrogen embrittlement was investigated. Auger electron spectroscopy was employed to determine the grain boundary compositions of nickel-copper alloys containing various concentrations of phosphorus and subjected to various thermal treatments. Phosphorus segregates to grain boundaries during slow cooling, accompanied by reduced concentrations of grain boundary copper. Tensile tests were conducted in air and following cathodic charging with… more
Date: January 1, 1980
Creator: Stein, D. F.; Heldt, L. A. & Funkenbusch, A. W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Anisotropy of oxygen tracer diffusion in YBa sub 2 Cu sub 3 O sub 7-. delta. single crystals

Description: The crystal structure of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} strongly suggests that the diffusion of oxygen in this material will be highly anisotropic, with diffusion in the ab plane being much faster than diffusion parallel to the c axis, and this has been assumed in most analyses of diffusion in YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}. The present data confirm this hypothesis; the diffusion coefficient in the ab plane is several orders of magnitude greater than the diffusion coefficient along th… more
Date: September 1, 1989
Creator: Rothman, S. J.; Routbort, J. L.; Liu, J.-Z.; Downey, J. W.; Thompson, L. J.; Fang, Y. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Load relaxation studies of zircaloy-4

Description: The results of the present work have shown (1) the load relaxation data of Zircaloy-4 in the temperature range of 200/sup 0/C to 385/sup 0/C can be represented by the phenomenological model based on Hart's plastic equation of state; (2) the room temperature load relaxation data reflect the effects of deformation twinning; (3) at higher temperatures the load relaxation data suggest the contribution of grain boundary sliding; and (4) the effects of strain aging can be identified based on the load… more
Date: January 1, 1976
Creator: Huang, F. H.; Sabol, G. P.; McDonald, S. G. & Li, C. Y.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Atomic matching across internal interfaces

Description: The atomic structure of internal interfaces in dense-packed systems has been investigated by high-resolution electron microscopy (HREM). Similarities between the atomic relaxations in heterophase interfaces and certain large-angle grain boundaries have been observed. In both types of interfaces localization of misfit leads to regions of good atomic matching within the interface separated by misfit dislocation-like defects. It appears that, whenever possible, the GB structures assume configurati… more
Date: January 1, 1989
Creator: Merkle, K.L. (Argonne National Lab., IL (USA))
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Light-water-reactor safety research program. Quarterly progress report, January-March 1981

Description: A mechanistic model for the prediction of microcracking (grain-boundary separation) during transient conditions has been generated within the context of the FASTGRASS computer code. A model based on the work of DiMelfi and Deitrich describing ductile/brittle behavior has been replaced by one based on the work of Beere and Speight, Chuang and Rice, and Chen and Argon. The theory underlying this new model is described and its proposed implementation in the prediction of DEH test results is outlin… more
Date: November 1, 1981
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Silicon-on ceramic process. Silicon sheet growth and device development for the large-area silicon sheet and cell development tasks of the low-cost solar array project. Quarterly report No. 12, April 2, 1979-June 29, 1979

Description: The objective of this research program is to investigate the technical and economic feasibility of producing solar-cell-quality sheet silicon. We plan to do this by coating one surface of carbonized ceramic substrates with a thin layer of large-grain polycrystalline silicon from the melt. During the quarter, significant progress was demonstrated in several areas: (1) a 10-cm/sup 2/ cell having 9.9 percent conversion efficiency (AM1, AR) was fabricated; (2) the Honeywall-sponsored SCIM coating d… more
Date: July 31, 1979
Creator: Chapman, P.W.; Zook, J.D.; Heaps, J.D.; Grung, B.L.; Koepke, B. & Schuldt, S.B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Indium phosphide/cadmium sulfide thin-film solar cells. Quarterly technical progress report No. 1, June 1979-August 1979

Description: Cadmium sulfide and InP thin films were prepared by thermal evaporation and planar reactive deposition, respectively. Polycrystalline CdS films up to 10 ..mu..m thick showed absorption losses of less than 10% over the 0.6- to 1.0-..mu..m wavelength range. A threefold increase in lateral grain size was achieved when CdS/ITO/GLASS structures were partially recrystallized in flowing H/sub 2/S/Ar at 550/sup 0/C. InP deposited onto (100) InP semiinsulating substrate at substrate temperatures as low … more
Date: November 1, 1979
Creator: Zanio, K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Fundamental studies of grain boundary passivation in polycrystalline silicon with application to improved photovoltaic devices. A final research report covering work completed from February-December 1979

Description: Several aspects of the electrical properties of silicon grain boundaries have been studied. The temperature dependence of the zero-bias conductance and capacitance of single boundaries has been measured and shown to be in good agreement with a simple double depletion layer/thermal emission (DDL/TE) model developed to predict the transport properties of such structures. In addition, it has been shown that deconvolution of the I-V properties of some boundaries via a deconvolution scheme suggested… more
Date: February 1, 1980
Creator: Seager, C. H. & Ginley, D. S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Irradiation effects on the electrochemistry and corrosion resistance of stainless steel

Description: Nickel-ion irradiation at 500{degrees}C is shown to have a strong effect on the surface electrochemistry and intergranular corrosion of stainless steel. Measured current densities in a 1N H{sub 2}SO{sub 4} solution at room temperature are increased at active-passive, passive, and transpassive potentials. Irradiation effects on the current decay behavior and susceptibility to intergranular corrosion were similar for a microcrystalline, fine-grained stainless alloy and for a very large-grained st… more
Date: April 1, 1992
Creator: Bruemmer, S. M.; Arey, B. W.; Windisch, C. F., Jr. & Cole, J. I.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
Back to Top of Screen