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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.
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Partner: UNT Libraries Government Documents Department
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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
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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.
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Partner: UNT Libraries Government Documents Department
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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.
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Partner: UNT Libraries Government Documents Department
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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
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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
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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
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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
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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))
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Partner: UNT Libraries Government Documents Department
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Study of grain boundary segregation using the Auger electron emission technique. Annual technical progress report, VIII, January 1-December 31, 1978

Description: The susceptibility of nickel-copper alloys to liquid metal embrittlement was studied by Auger spectroscopy. Alloys corresponding to Monel 400 with various levels of additional phosphorous were employed and were given various thermal treatments to control the extent of segregation. Segregation of phosphorous to the boundaries, with accompanying decreases in copper and nickel concentrations, greatly reduces susceptibility to intergranular embrittlement by mercury.
Date: January 1, 1978
Creator: Stein, D. F.; Heldt, L. A. & Funkenbusch, A. W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Mechanical properties and microstructure of pressureless sintered duophase sialon

Description: Duophase ({alpha}{prime}/{beta}{prime}) sialon is being developed for ceramic engine applications by using the Quickset{trademark} injection molding process, followed by pressureless sintering and a thermal treatment. The sialon had an average four-point flexural strength of 670 MPa at room temperature and 490 MPa at 1370{degree}C. It survived the flexural stress rupture test at 1300{degree}C and 340 MPa for 190 hours. X-ray diffraction (XRD) and transmission electron microscopy (TEM) character… more
Date: January 1, 1991
Creator: Lee, Ran-Rong; Novich, B.E.; Franks, G.; Quellette, D. (Ceramics Process Systems Corp., Milford, MA (United States)); Ferber, M.K.; Hubbard, C.R. et al.
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Partner: UNT Libraries Government Documents Department
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Application of analytical electron microscopy to the study of intergranular corrosion in 304 stainless steel

Description: The technique of analytical electron microscopy in a scanning transmission electron microscope fitted with an energy dispersive x-ray spectrometer is used to measure the chromium depletion in sensitized 304 stainless steel along the grain boundaries. It is shown that such measurements could be misleading unless care is taken to properly choose the regions on the grain boundaries for such analysis.
Date: January 1, 1980
Creator: Pande, C. S. & Sabatini, R. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Helium induced degradation in the weldability of an austenitic stainless steel

Description: Autogenous gas tungsten arc welding was performed on He-doped type 316 stainless steel. Helium was uniformly implanted in the material using the ''tritium trick'' to levels of 27 and 105 appm. Severe intergranular cracking occurred in both fusion and heat-affected zones. Microstructural observations of fusion zone indicated that the pore size, degree of porosity, and tendency to form cracks increased with increasing helium concentration. Scanning electron microscopy showed that cracking in He-d… more
Date: January 1, 1988
Creator: Lin, H. T.; Goods, S. H.; Grossbeck, M. L. & Chinl, B. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Trapping site location for Sb in Fe-Ti-Sb-C alloys

Description: The lattice location of Sb trapped at TiC precipitates in Fe has been determined. Channeling analysis of ion-backscattering and ion-induced characteristic x-ray yields from Fe and Sb showed a substitutionality of greater than or equal to 50% for trapped Sb relative to the Fe lattice for ion beams incident along Fe (100), (110), and (111). In contrast, Ti x-ray yields showed channeling through the oriented TiC precipitates only along Fe (100). We conclude that Sb is trapped at interfacial Fe sit… more
Date: January 1, 1980
Creator: Knapp, J. A. & Follstaedt, D. M.
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Partner: UNT Libraries Government Documents Department
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Effects of test environment and grain size on the tensile properties of L1 sub 2 -ordered (Co,Fe) sub 3 V alloys

Description: The influence of test environment, grain size, and heat treatment on the tensile properties and fracture behavior of L1{sub 2}-ordered (Co{sub 78}Fe{sub 22}){sub 3}V and (Co{sub 85}Fe{sub 15}){sub 3}V alloys was studied at room temperature. The tensile ductility depends strongly on test environments; the elongation decreases in the sequence of oxygen, vacuum, air, and distilled water. The loss in elongation is accompanied by a change in fracture mode from transgranular to intergranular. When te… more
Date: January 1, 1991
Creator: Nishimura, C. & Liu, C.T.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The feasibility of welding of irradiated materials

Description: Helium was implanted into solution-annealed (SA) 316 stainless steel, 20% cold-worked (CW) 316 stainless steel and titanium-modified Primary Candidate Alloy (PCA) through tritium decay to levels ranging from 0.18 to 256 appm. Full penetration welds were then made on helium-doped materials using gas tungsten arc welding (GTAW) under fully constrained conditions. Intergranular heat-affected zone (HAZ) cracking was observed in all of the materials containing greater than 1 appm He. Electron micros… more
Date: January 1, 1989
Creator: Lin, H. T.; Chin, B. A. (Oak Ridge National Lab., TN (USA) & Auburn Univ., AL (USA). Dept. of Materials Engineering)
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Partner: UNT Libraries Government Documents Department
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Stress relaxation and hillock growth in thin films

Description: The relaxation of thermal stress in a thin film adhering to a substrate of differing expansion coefficient is discussed. Good agreement is found between literature data on relaxation during isothermal anneals of Pb films at up to 350/sup 0/K and model calculations based on a state variable description of plastic flow. The stress system during relaxation is explored, and the absence of diffusional creep is explained. The plasticity-dominated relaxation process suggested by this analysis is shown… more
Date: January 1, 1978
Creator: Jackson, M. S. & Li, C. Y.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Photovoltaic mechanisms in polycrystalline thin film solar cells. Quarterly technical progress report No. 3, April 1-June 30, 1979

Description: The vertical junction effect in polysilicon solar cells (due to dopant penetration along grain boundaries) is investigated using a cylindrical grain model. The model shows that for small grain radii the short circuit current can increase above the single crystal value if the grain boundaries collect carriers and that th short-circuit current approaches the single crystal value as the grain size increases. The spatial dependence of the dark I-V characteristic is investigated by fabricating small… more
Date: January 1, 1979
Creator: Storti, G.; Johnson, S.; Lin, H. C. & Armstrong, R. W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Diffusion-controlled decohesion using a Cu-Sn alloy as a model system

Description: This research deals with a mode of brittle intergranular fracture in which a surface adsorbed embrittling element is driven into a grain boundary as a result of the application of a tensile stress across the boundary. A Cu-8%Sn alloy has been employed to explore this phenomenon, since tin is a surface-active element, and this alloy is known to suffer intergranular weakness at elevated temperatures. Intergranular cracking occurred by brittle, discontinuous crack advance at 265{degrees}C in vacuu… more
Date: January 1, 1991
Creator: Bika, D. & McMahon, C.J. Jr.
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Partner: UNT Libraries Government Documents Department
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Lifetime improvement of sheathed thermocouples for use in high-temperature and thermal transient operations

Description: Premature failure of small-diameter, magnesium-oxide-insulated sheathed thermocouples occurred when they were placed within nuclear fuel rod simulators (FRSs) to measure high temperatures and to follow severe thermal transients encountered during simulation of nuclear reactor accidents in Oak Ridge National Laboratory (ORNL) thermal-hydraulic test facilities. Investigation of thermally cycled thermocouples yielded three criteria for improvement of thermocouple lifetime: (1) reduction of oxygen … more
Date: January 1, 1982
Creator: McCulloch, R.W. & Clift, J.H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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