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Sample records for a-si alloy production

  1. Large-area, triple-junction a-Si alloy production scale-up

    SciTech Connect

    Oswald, R.; O'Dowd, J. . Thin Film Div.)

    1993-04-01

    This report describes Solarex's work to advance its photovoltaic manufacturing technologies, reduce its a-Si:H module production costs, increase module performance, and expand the Solarex commercial production capacity. Solarex will meet these objectives by improving the deposition and quality of the transport front contact; optimizing the laser patterning process; scaling up the semiconductor deposition process; improving the back-contact deposition; and scaling up and improving the encapsulation and testing of its a-Si:H modules. In the Phase 1 portion of this subcontract, Solarex focused on scaling up components of the chemical vapor deposition system for deposition of the system contact, scaling up laser scribing techniques; triple-junction recipes for module production; and metal-oxide back contacts. The goal of these efforts is to adopt all portions of the manufacturing line to handle substrates larger than 0.37 m[sup 2].

  2. Large-area, triple-junction a-Si alloy production scale-up. Semiannual technical progress report, 17 March 1992--18 September 1992

    SciTech Connect

    Oswald, R.; O`Dowd, J.

    1993-04-01

    This report describes Solarex`s work to advance its photovoltaic manufacturing technologies, reduce its a-Si:H module production costs, increase module performance, and expand the Solarex commercial production capacity. Solarex will meet these objectives by improving the deposition and quality of the transport front contact; optimizing the laser patterning process; scaling up the semiconductor deposition process; improving the back-contact deposition; and scaling up and improving the encapsulation and testing of its a-Si:H modules. In the Phase 1 portion of this subcontract, Solarex focused on scaling up components of the chemical vapor deposition system for deposition of the system contact, scaling up laser scribing techniques; triple-junction recipes for module production; and metal-oxide back contacts. The goal of these efforts is to adopt all portions of the manufacturing line to handle substrates larger than 0.37 m{sup 2}.

  3. Large-area triple-junction a-Si alloy production scaleup. Annual subcontract report, 17 March 1993--18 March 1994

    SciTech Connect

    Oswald, R.; Morris, J.

    1994-11-01

    The objective of this subcontract over its three-year duration is to advance Solarex`s photovoltaic manufacturing technologies, reduce its a-Si:H module production costs, increase module performance and expand the Solarex commercial production capacity. Solarex shall meet these objectives by improving the deposition and quality of the transparent front contact, by optimizing the laser patterning process, scaling-up the semiconductor deposition process, improving the back contact deposition, scaling-up and improving the encapsulation and testing of its a-Si:H modules. In the Phase 2 portion of this subcontract, Solarex focused on improving deposition of the front contact, investigating alternate feed stocks for the front contact, maximizing throughput and area utilization for all laser scribes, optimizing a-Si:H deposition equipment to achieve uniform deposition over large-areas, optimizing the triple-junction module fabrication process, evaluating the materials to deposit the rear contact, and optimizing the combination of isolation scribe and encapsulant to pass the wet high potential test. Progress is reported on the following: Front contact development; Laser scribe process development; Amorphous silicon based semiconductor deposition; Rear contact deposition process; Frit/bus/wire/frame; Materials handling; and Environmental test, yield and performance analysis.

  4. Structural and electronic studies of a-SiGe:H alloys

    SciTech Connect

    Paul, W. )

    1993-04-01

    This report describes work to produce alloys of a-Si[sub 1-x]Ge[sub x]:H of improved photoelectronic quality by plasma-enhanced chemical vapor deposition (PECVD). The goal was to discover optimum preparation conditions for the end-component, a-Ge:H, to establish whether modification of the usual practice of starting from a-Si:H preparation conditions was advisable. Such modification, found to be necessary, gave films of a-Ge:H with efficiency-mobility-lifetime products ([eta][mu][tau]) 10[sup 2] to 10[sup 3] higher than were earlier available, in homogeneous environmentally stable material. Both a-Ge:H and a-Si[sub 1-x]Ge[sub x]:H of large x were studied in detail. Alloy material was shown to have [eta][mu][tau] 10[sup 2] larger than found earlier. However, just as the [eta][mu][tau] of a-Si:H decreases when Ge is added, so also the [eta][mu][tau] of these alloys with Si addition. By contrast, the ambipolar diffusion lengths, L[sub o] which are governed by the hole mobility, vary by only a factor of two over the whole alloy series. Using the experimental finding of a small valence band offset between a-Si:H and a-Ge:H compositional fluctuations on a 10-mm scale are suggested to explain the behavior of [eta][mu][tau] and L[sub o] The implications for eventual improvement of the alloys are profound, but require direct experimental tests of the postulated compositional fluctuations.

  5. Development of high stable-efficiency, triple-junction a-Si alloy solar cells. Annual subcontract report, July 18, 1994--July 17, 1995

    SciTech Connect

    Deng, X.

    1996-02-01

    This report describes work performed by Energy Conversion Devices, Inc. (ECD) under a 3-year, cost-shared amorphous silicon (a-Si) research program to develop advanced technologies and to demonstrate stable 14%-efficient, triple-junction a-Si alloy solar cells. The technologies developed under the program will then be incorporated into ECD`s continuous roll-to-roll deposition process to further enhance ECD`s photovoltaic manufacturing technology. In ECD`s solar cell design, triple-junction a-Si alloy solar cells are deposited onto stainless-steel substrates coated with Ag/ZnO back-reflector layers. This type of cell design enabled ECD to use a continuous roll- to-roll deposition process to manufacture a-Si PV materials in high volume at low cost. Using this cell design, ECD previously achieved 13.7% initial solar cell efficiency using the following features: (1) a triple-junction, two-band-gap, spectrum-splitting solar cell design; (2) a microcrystalline silicon p-layer; (3) a band-gap-profiled a- SiGe alloy as the bottom cell i-layer; (4) a high-performance AgZnO back-reflector; and (5) a high-performance tunnel junction between component cells. ECD also applied the technology into its 2-MW/yr a- Si production line and achieved the manufacturing of 4-ft{sup 2} PV modules with 8% stable efficiency. During this program, ECD is also further advancing its existing PV technology toward the goal of 14% stable solar cells by performing the following four tasks: (1) improving the stability of the intrinsic a-Si alloy materials; (2) improving the quality of low-band-gap a-SiGe alloy; (3) improving p{sup +} window layers, and (4) developing high stable-efficiency triple-junction a-Si alloy solar cells.

  6. Microscopic origins of metastable effects in a-Si:H and deep defect characterization in a-Si,Ge:H alloys

    SciTech Connect

    Cohen, J.D. )

    1992-07-01

    This report describes works to use transient photocapacitance and photocurrent measurements to determine the deep defect distribution and processes in low-band-gap a-Si,Ge:H alloys. Samples for these studies were produced by the photochemical vapor deposition (photo-CVD) growth method and were obtained through a collaboration with researchers at the University of Delaware. This report discusses how a detailed comparison between the photocapacitance and photocurrent spectra can be used to separately examine the majority and minority carrier processes. The results are as follows: (1) The midgap defect densities in the alloy regime near 1.3 eV can be as low as 5 {times} 10{sup 16} cm{sup {minus}3} in such photo-CVD samples. (2) There exists a second defect band roughly 0.4 eV below E{sub c} of a similar magnitude to the midgap defect density that exhibits significant lattice relaxation behavior in its electron trapping dynamics. (3) The hole {mu}{tau} products determined for the lowest defect sample are roughly 5 {times} 10{sup {minus}10} cm{sup 2}/V, comparable with the highest hole {mu}{tau} products reported in sandwich geometry measurements for alloys in this composition range. (4) The hole {mu}{tau} is found to be roughly inversely proportional to the midgap defect density for the samples studied. This is consistent with the fact that the effective minority carrier lifetime for such measurements is limited by the deep state trapping time.

  7. Pulsed Nd-YAG laser welding of A SiC particulate reinforced aluminium alloy composite

    NASA Astrophysics Data System (ADS)

    Yue, T. M.; Xu, J. H.; Man, H. C.

    1997-01-01

    This paper examines the laser welding behaviour of a SiC particulate reinforced Al-alloy 2124 composite using a pulsed Nd-YAG laser. The influences of laser welding parameters of laser intensity, pulse duration and the beam's focus position on the depth of weld penetration as well as the size of fusion zone were investigated. These investigations have led to an optimum welding condition proposed for pulsed laser welding of SiC particulate reinforced aluminium alloy composites with minimum defects.

  8. Comprehensive research on the stability and electronic properties of a-Si:H and a-SiGe:H alloys and devices. Final subcontract report, 10 March 1991--30 August 1994

    SciTech Connect

    Dalal, V.

    1995-04-01

    This report describes work on the growth of a-Si:H and a-(Si,Ge):H materials and devices using well-controlled growth techniques. The a-Si:H materials were grown at higher temperatures (300{degrees}-375{degrees}C) using electron-cyclotron-resonance (ECR) plasma techniques with a remote H beam. These films have excellent electronic quality and show significant improvements in stability compared with glow-discharge-produced a-Si:H materials. Several problems were encountered during the fabrication of devices in these materials, and we were able to overcome them by a systematic work on buffer layers in these cells. We also studied alternative designs for improving the stability of a-Si:H cells and produced graded-gap a-Si:H cells using glow-discharge that are more stable than comparable standard, ungraded glow discharge devices. Finally, systematic work was done to produce good-quality a-(Si,Ge):H films, using triode radio frequency (RF) glow-discharge with ion bombardment during growth. Diagnostic devices were made using these films, and the properties of the material, such as Urbach energies and hole mobility-lifetime products, were measured in these devices. We found a systematic increase in the Urbach energies, and a corresponding decrease in the hole and electron {mu}{tau} products, as the Ge content of the alloys increases.

  9. Modeling of a-Si:H alloy solar cells on textured substrates

    SciTech Connect

    Zeman, M.; Berg, J.H. van den; Vosteen, L.L.A.; Willemen, J.A.; Metselaar, J.W.; Schropp, R.E.I.

    1997-07-01

    Computer modeling is used as a tool for determining current matching in hydrogenated amorphous silicon (a-Si:H) alloy tandem cells on textured substrates. The increasing complexity of a-Si:H based solar cells requires continuous extending and testing of the computer models which are used for their simulation. To take light scattering at the textured interfaces of the cell into account the authors developed a multi-rough-interface optical model GENPRO2 which was used for calculating the absorption profiles in the solar cells. The results of a sensitivity study of the parameters of this optical model such as the scattering coefficients of the reflected and transmitted light and the dependence of scattered light on the in-going and out-going angle are presented. In order to simulate multi-junction solar cell as a complete device they implemented a novel model for tunnel/recombination junction (TRJ), which combines the trap assisted tunneling and enhanced carrier transport in the high field region of the TRJ. The current matching conditions were determined both for a-Si:H and a-SiGe:H bottom cells, while the top cell was an a-Si:H cell. They investigated the influence of light scattering at the textured interfaces and of the thickness of the intrinsic layer of the bottom cell on the optimal ratio (i2/i1) between the thicknesses of the bottom (i2) and top (i1) intrinsic layers in the current-matched cell. The results show that increasing amount of scattering at the textured interfaces leads to higher efficiencies and lower ratio (i2/i1) in the current-matched cell. The use of a-SiGe:H material in the bottom cell leads to higher efficiency and 3 to 4 times lower i2/i1 ratio than in case of a-Si:H/a-Si:H cells.

  10. Light-induced degradation in a-Si alloy solar cells at intense illumination

    NASA Astrophysics Data System (ADS)

    Banerjee, A.; Guha, S.; Pawlikiewicz, A.; Wolf, D.; Yang, J.

    1991-08-01

    Light-induced degradation has been investigated in a-Si alloy p-i-n solar cell structures as a function of cell deposition temperature and light intensity. Cells are deposited at temperatures ranging between 200°C to 300°C; degradation has been carried out at intensities up to 50 times AM1.5 illumination at 35°C. The cell charcteristics have been measured under AM1.5, blue and red illuminations. The degradation is found to have a power law dependence on the product of square of generation rate and light-soaking time. Most cells show saturation in degradation under 50 times AM1.5 illumination beyond 1000 sec, which is equivalent to approximately 800 hours under AM1.5 intensity. However, somes cells showed continued degradation at the high intensity up to 6×104 sec without any saturation; the cell properties could be restored to their original values after annealing. Computer simulation studies have been carried out to analyze the results on the basis of existing theories.

  11. a-Si:H solar cells: SiH(2)Cl(2) as a source gas and a-SiGe:H alloys

    NASA Astrophysics Data System (ADS)

    Payne, Adam More

    This thesis gives an overview of the reasons why solar cells are a necessity in this world of carbon constrained energy use. The most important factors upon which to work to improve the competitiveness of photovoltaic generated electricity with conventional, fossil fuel based generation are the cost of the solar cell and the cell conversion efficiency. The two main technical thrusts of this thesis--DCS as a source gas and a-SiGe:H alloys--attacked two aspects of these problems. a-SiGe:H is used in multijunction cells to achieve higher efficiencies and DCS can be used to increase the deposition rate of a-Si:H thus decreasing the time it takes to make a solar cell. We review the various experimental methods used to investigate the optical and electronic properties of a-Si:H thin films as well as the methods used to measure solar cell efficiency and determine the effectiveness of the various portions of a solar cell. Using DCS as a source gas helped us increase the deposition rate by factor of 5 while maintaining the film quality; however chlorinated intrinsic films had higher defect densities and lower photoconductivity than standard a-Si:H films. Use of DCS to deposit i-layers of a solar cell led us to the discovery that Cl enhances the doping efficiency of B in a-Si:H. The enhanced doping of a-SiC:H as the p-layer of a solar cell increased the cell's efficiency from 7.1% to 7.8%. A-SiGe:H alloys were investigated over a range of Tauc gaps from 1.7 eV down to 1.0 eV. The optical and electronic properties of these films were investigated as well as their incorporation in solar cells. Different bandgap graded structures were used in the i-layer of a solar cell with the conclusion that the bathtub shaped i-layer yields the highest stabilized efficiency. An attempt was made to fabricate solar cells using cathode-deposited a-SiGe:H alloys as the i-layer in collaboration with Harvard University. The cells fabricated could neither prove nor disprove the effectiveness of

  12. Structural and electronic studies of a-SiGe:H alloys. Final subcontract report, 1 January 1991--28 February 1993

    SciTech Connect

    Paul, W.

    1993-04-01

    This report describes work to produce alloys of a-Si{sub 1-x}Ge{sub x}:H of improved photoelectronic quality by plasma-enhanced chemical vapor deposition (PECVD). The goal was to discover optimum preparation conditions for the end-component, a-Ge:H, to establish whether modification of the usual practice of starting from a-Si:H preparation conditions was advisable. Such modification, found to be necessary, gave films of a-Ge:H with efficiency-mobility-lifetime products ({eta}{mu}{tau}) 10{sup 2} to 10{sup 3} higher than were earlier available, in homogeneous environmentally stable material. Both a-Ge:H and a-Si{sub 1-x}Ge{sub x}:H of large x were studied in detail. Alloy material was shown to have {eta}{mu}{tau} 10{sup 2} larger than found earlier. However, just as the {eta}{mu}{tau} of a-Si:H decreases when Ge is added, so also the {eta}{mu}{tau} of these alloys with Si addition. By contrast, the ambipolar diffusion lengths, L{sub o} which are governed by the hole mobility, vary by only a factor of two over the whole alloy series. Using the experimental finding of a small valence band offset between a-Si:H and a-Ge:H compositional fluctuations on a 10-mm scale are suggested to explain the behavior of {eta}{mu}{tau} and L{sub o} The implications for eventual improvement of the alloys are profound, but require direct experimental tests of the postulated compositional fluctuations.

  13. Microscopic origins of metastable effects in a-Si:H and deep defect characterization in a-Si,Ge:H alloys. Annual subcontract report, 1 February 1992--31 January 1993

    SciTech Connect

    Cohen, J.D.

    1993-08-01

    This report describes work to evaluate low-mobility-gap a-Si,Ge:H alloy films. Results are based on junction capacitance techniques of admittance spectroscopy, transient photocapacitance (and photocurrent), and drive-level capacitance profiling. Eight a-Si,Ge:H alloy samples grown by photo-CVD encompassed the range of optical gaps from 1.3 to 1.6 eV, and corresponding Ge fractions from about 20 to 60 at%. We employed junction capacitance techniques to determine deep defect energies and densities, Urbach band-tail energies, and {mu}{tau} products for holes. Electron microprobe analysis provided accurate Ge fractions for our samples, thus enabling us to establish clear trends in measured electronic properties vs Ge fraction. We concluded that these photo-CVD samples exhibited equal or superior properties in terms of band-tail widths, and stable defect densities compared to any reported results on a-Si,Ge:H samples grown by glow discharge. By assigning defect energy levels from analysis of transient subband-gap photocapacitance and photocurrent spectra, we found clear evidence for two distinct defect subbands, one at roughly midgap and the other in the upper half of the gap. The trapping lifetime related {mu}{tau} products for holes decreased in direct proportion to the density of mid-gap defects in these samples. This appears to be the case regardless of whether we are dealing with stable defects or defects created by light-soaking.

  14. Microscopic origins of metastable effects in a-Si:H and deep defect characterization in a-Si,Ge:H alloys. Final subcontract report, February 1, 1991--January 31, 1994

    SciTech Connect

    Cohen, J.D.

    1994-09-01

    This research supported by NREL Subcontract XG-1-10063-1 over the past three years has involved, first of all, a fairly complete characterization of a two series of a-Si{sub 1-x}Ge{sub x}:H samples: a series of 9 films grown at the University of Delaware by the photo-CVD method (for 0.29 {<=} {times} {<=} 0.62) and series of 6 films grown at U.S.S.C. by the glow discharge method (for 0.20 {<=} {times} {<=} 0.50). Both these series of samples seem to represent what is close to the {open_quotes}state-of-the-art{close_quotes} in current a-Si,Ge:H alloys. The authors detailed comparison of the properties of the glow discharge material with the photo-CVD samples show remarkable similarities rather than significant differences. In particular, measurements of these samples: (1) allowed the assignment of defect energy levels from a detailed analysis of transient sub-band-gap photocapacitance and photocurrent spectra. (2) The authors found the density of deep defects to increase exponentially with the germanium content. (3) The authors found that the trapping lifetimes related {mu}{tau} products for holes decrease in direct proportion to the density of midgap defects in these samples, at least up to Ge fractions of 50at.%. (4) The authors have also made significant progress toward identifying both the optical and thermal defect transitions in the a-Si,Ge:H alloys.

  15. Development of high, stable-efficiency triple-junction a-Si alloy solar cells. Final technical report

    SciTech Connect

    Deng, X.; Jones, S.J.; Liu, T.; Izu, M.

    1998-04-01

    This report summarizes Energy Conversion Devices, Inc.`s (ECD) research under this program. ECD researchers explored the deposition of a-Si at high rates using very-high-frequency plasma MHz, and compared these VHF i-layers with radio-frequency (RF) plasma-deposited i-layers. ECD conducted comprehensive research to develop a {mu}c-Si p{sup +} layer using VHF deposition process with the objectives of establishing a wider process window for the deposition of high-quality p{sup +} materials and further enhancing their performance of a-Si solar cells by improving its p-layers. ECD optimized the deposition of the intrinsic a-Si layer and the boron-doped {mu}c-Si p{sup +} layer to improve the V{sub oc}. Researchers deposited wide-bandgap a-Si films using high hydrogen dilution; investigated the deposition of the ZnO layer (for use in back-reflector) using a sputter deposition process involving metal Zn targets; and obtained a baseline fabrication for single-junction a-Si n-i-p devices with 10.6% initial efficiency and a baseline fabrication for triple-junction a-Si devices with 11.2% initial efficiency. ECD researchers also optimized the deposition parameters for a-SiGe with high Ge content; designed a novel structure for the p-n tunnel junction (recombination layer) in a multiple-junction solar cell; and demonstrated, in n-i-p solar cells, the improved stability of a-Si:H:F materials when deposited using a new fluorine precursor. Researchers investigated the use of c-Si(n{sup +})/a-Si alloy/Pd Schottky barrier device as a tool for the effective evaluation of photovoltaic performance on a-Si alloy materials. Through alterations in the deposition conditions and system hardware, researchers improved their understanding for the deposition of uniform and high-quality a-Si and a-SiGe films over large areas. ECD researchers also performed extensive research to optimize the deposition process of the newly constructed 5-MW back-reflector deposition machine.

  16. Fabrication of Source/Drain Electrodes for a-Si:H Thin-Film Transistors Using a Single Cu Alloy Target

    NASA Astrophysics Data System (ADS)

    Lee, J. H.; Lee, C. Y.; Nam, H. S.; Lee, J. G.; Yang, H. J.; Ho, W. J.; Jeong, J. Y.; Koo, D. H.

    2011-11-01

    A Cu alloy/Cu alloy oxide bilayer structure was formed on an n +-a-Si:H substrate using a single Cu alloy target. It was employed for the source/drain electrodes in the fabrication of a-Si:H thin-film transistors with good electrical performance, high thermal stability, and good adhesion. Transmission electron microscopy and electron energy-loss spectroscopy analyses revealed that the initial sputtering of the Cu alloy in O2/Ar allowed for preferential oxidation of Si and the formation of a SiO x /Cu-supersaturated a-Si:H bilayer at the copper oxide-a-Si:H interface. This bilayer turned into an SiO x /Cu3Si bilayer after annealing at 300°C. It provided a stable contact structure with low contact resistance.

  17. Microscopic origins of metastable effects in a-Si:H and deep defect characterization in a-Si,Ge:H alloys. Annual subcontract report, 1 February 1991--31 January 1992

    SciTech Connect

    Cohen, J.D.

    1992-07-01

    This report describes works to use transient photocapacitance and photocurrent measurements to determine the deep defect distribution and processes in low-band-gap a-Si,Ge:H alloys. Samples for these studies were produced by the photochemical vapor deposition (photo-CVD) growth method and were obtained through a collaboration with researchers at the University of Delaware. This report discusses how a detailed comparison between the photocapacitance and photocurrent spectra can be used to separately examine the majority and minority carrier processes. The results are as follows: (1) The midgap defect densities in the alloy regime near 1.3 eV can be as low as 5 {times} 10{sup 16} cm{sup {minus}3} in such photo-CVD samples. (2) There exists a second defect band roughly 0.4 eV below E{sub c} of a similar magnitude to the midgap defect density that exhibits significant lattice relaxation behavior in its electron trapping dynamics. (3) The hole {mu}{tau} products determined for the lowest defect sample are roughly 5 {times} 10{sup {minus}10} cm{sup 2}/V, comparable with the highest hole {mu}{tau} products reported in sandwich geometry measurements for alloys in this composition range. (4) The hole {mu}{tau} is found to be roughly inversely proportional to the midgap defect density for the samples studied. This is consistent with the fact that the effective minority carrier lifetime for such measurements is limited by the deep state trapping time.

  18. Research on the stability, electronic properties, and structure of a-Si:H and its alloys

    SciTech Connect

    Street, R.A.; Jackson, W.B.; Johnson, N.; Nebel, C.; Hack, M.; Santos, P.; Thompson, R.; Tsai, C.C.; Walker, J. )

    1992-12-01

    Objective is to obtain a comprehensive understanding of structure and electronic properties of a-Si:H as they apply to solar cells. First observations were of light enhancement and field suppression of H diffusion in a-Si:H. Theoretical studies were made of hydrogen density of states distribution and its relation to defect metastability. Reduced density of light induced defect is observed in a-Si:H deposited in a remote hydrogen plasma reactor at 400 C. Kinetics of metastable defect creation using forward bias in a p-i-n diode to induce defects were studied and compared to light-induced defect creation in the same devices. Studies were made of transport at high electric field and low temperature. Detailed studies were made of kinetics of dopant metastability in n-type and p-type a-Si:H.

  19. Research on the stability, electronic properties, and structure of a-Si:H and its alloys. Final subcontract report, 1 June 1991--31 May 1994

    SciTech Connect

    Jackson, W.B.; Johnson, N.; Nickel, N.; Schumm, G.; Street, R.A.; Thompson, R.; Tsai, C.C.; Van de Walle, C.; Walker, J.

    1995-07-01

    The authors research has focused on defect metastability and a-Si:C:H alloys. A new aspect of the metastability is the growing interest in the defect recovery process. They have continued to explore the role of hydrogen in the metastability and other properties of a-Si:H. This has led them to perform first principles calculations of Si-H bonding configurations. Another new feature of the metastability work is the study of the effects in hydrogenated poly-silicon. They have grown and studied the properties of a-Si:C:H alloys, particularly to observe the effects of hydrogen dilution. Finally they have also studied the recent defect relaxation phenomenon, and concluded that the effects arise from contact effects and are not an intrinsic effect in a-Si:H. Section A presents some recent models of metastability. Section B discusses the metastability and equilibration effects in hydrogenated polysilicon, studied because of it`s close similarity to a-Si:H. Section C describes results on a-Si:C:H alloys. Section D contains first principle LDA calculations of Si-H bonds and relates these results to the a-Si:H diffusion and metastability properties. In section E the authors report capacitance measurements aimed at exploring the recent results by Cohen et al who find an anomalous relaxation process from the trap filling kinetics of a DLTS experiment.

  20. Space-charge-limited currents: Refinements in analysis and applications to a-Si1 - xGexH alloys

    NASA Astrophysics Data System (ADS)

    Weisfield, R. L.

    1983-11-01

    A new algorithm is described for deriving the density of states N(E) from the Fermi energy EF upwards toward the conduction band edge. This refinement in the analysis of space-charge-limited currents (SCLC) enables the accurate determination of N(E) by implicitly accounting for the spatial variations of physical quantities across the thickness of the diode. SCLC is measured in NiCr/n+/a-Si1-xGex: H/Pt diode structures. For a-Si:H samples, SCLC values for N(EF) are compared to those derived from admittance measurements on the same diodes. The two determinations agree in samples where 1016a-Si0.7Ge0.3: H is also investigated, as a function of hydrogen content cH, optical gap, and photoluminescence intensity IPL. In this alloy increasing cH causes N(EF) to decrease, to a minimum of 3×1016 for cH=14 at. %. IPL increases inversely with N(EF), confirming the sensitivity of SCLC to bulk nonradiative recombination centers. It is concluded that the SCLC measurement and analysis constitute a relatively simple, straightforward, and generally applicable method of obtaining the density of states in the gap of amorphous semiconductors.

  1. Precipitation Sequence of a SiC Particle Reinforced Al-Mg-Si Alloy Composite

    NASA Astrophysics Data System (ADS)

    Shen, Rujuan; Wang, Yihan; Guo, Baisong; Song, Min

    2016-11-01

    In this study, the precipitation sequence of a 5 vol.% SiC particles reinforced Al-1.12 wt.%Mg-0.77 wt.%Si alloy composite fabricated by traditional powder metallurgy method was investigated by transmission electron microscopy and hardness measurements. The results indicated that the addition of SiC reinforcements not only suppresses the initial aging stage but also influences the subsequent precipitates. The precipitation sequence of the composite aged at 175 °C can be described as: Guinier-Preston (G.P.) zone → β″ → β' → B', which was confirmed by high-resolution transmission electron microscopy. This work might provide the guidance for the design and fabrication of hardenable automobile body sheet by Al-based composites with enhanced mechanical properties.

  2. Tritium Production from Palladium Alloys

    SciTech Connect

    Claytor, T.N.; Schwab, M.J.; Thoma, D.J.; Teter, D.F.; Tuggle, D.G.

    1998-04-19

    A number of palladium alloys have been loaded with deuterium or hydrogen under low energy bombardment in a system that allows the continuous measurement of tritium. Long run times (up to 200 h) result in an integration of the tritium and this, coupled with the high intrinsic sensitivity of the system ({approximately}0.1 nCi/l), enables the significance of the tritium measurement to be many sigma (>10). We will show the difference in tritium generation rates between batches of palladium alloys (Rh, Co, Cu, Cr, Ni, Be, B, Li, Hf, Hg and Fe) of various concentrations to illustrate that tritium generation rate is dependent on alloy type as well as within a specific alloy, dependent on concentration.

  3. Low-cycle fatigue properties of a SiC whisker-reinforced 2124 aluminum alloy

    SciTech Connect

    Sasaki, M. ); Lawson, L.; Meshii, M. . Dept. of Materials Science and Engineering)

    1994-10-01

    Low-cycle fatigue microcracking leading to failure of smooth specimens of a powder metallurgy (PM) 2124 aluminum alloy reinforced with 20 vol pct SiC whiskers was studied. The crack size near the onset of unstable growth was inferred to be 50 to 70 [mu]m in the stress amplitude range of the present study (400 to 600 MPa, R = [minus]1) from observations of the fracture surfaces of the specimens. This corresponds to stress intensities between 1/3 to 1/2 typical values of K[sub 1c] or 1/4 to 1/9 the critical length predicted from K[sub 1c] values of 12 to 14 MPa[radical]m. The microcrack size distributions and growth data were obtained from the low-cycle fatigue specimens at various stages of fatigue, using a surface replica technique. During continued cycling, microcracks formed and were lost through linkage with other cracks. At the same time, the fraction of small cracks (< 5 [mu]m) decreased, while that of larger cracks (> 5 [mu]m) increased. The total number of cracks increased with increasing numbers of cycles.

  4. Low-Cycle fatigue properties of a SiC Whisker-reinforced 2124 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Sasaki, M.; Lawson, L.; Meshii, M.

    1994-10-01

    Low-cycle fatigue microcracking leading to failure of smooth specimens of a powder metallurgy (PM) 2124 aluminum alloy reinforced with 20 vol pct SiC whiskers was studied. The crack size near the onset of unstable growth was inferred to be 50 to 70 µm in the stress amplitude range of the present study (400 to 600 MPa, R = -1) from observations of the fracture surfaces of the specimens. This corresponds to stress intensities between 1/3 to 1/2 typical values of K 1c or 1/4 to 1/9 the critical length predicted from K 1c values of 12 to 14 MPa√m. The microcrack size distributions and growth data were obtained from the low-cycle fatigue specimens at various stages of fatigue, using a surface replica technique. During continued cycling, microcracks formed and were lost through linkage with other cracks. At the same time, the fraction of small cracks (<5 µm) decreased, while that of larger cracks (>5 µm) increased. The total number of cracks increased with increasing numbers of cycles. Typical microcrack growth rates were determined to be db/dn = (3.57 to 6.11) × 10-10 (Δ/ K)2.2to2.48 in the lateral direction of the crack, and da/dn = (5.83 to 13.0) × 10-11 (Δ K)1.54 to 1.60 in the depth direction of the crack.

  5. In vitro evaluation of diamond-like carbon coatings with a Si/SiC x interlayer on surgical NiTi alloy

    NASA Astrophysics Data System (ADS)

    Liu, C. L.; Chu, Paul K.; Yang, D. Z.

    2007-04-01

    Diamond-like carbon (DLC) coatings were produced with a Si/SiCx interlayer by a hybrid plasma immersion ion implantation and deposition process to improve the adhesion between the carbon layer and surgical NiTi alloy substrate. The structure, mechanical properties, corrosion resistance and biocompatibility of the coatings were evaluated in vitro by Raman spectroscopy, pin-on-disk tests, potentiodynamic polarization tests and simulated fluid immersion tests. The DLC coatings with a Si/SiCx interlayer of a suitable thickness have better adhesion, lower friction coefficients and enhanced corrosion resistance. In the simulated body fluid tests, the coatings exhibit effective corrosion protection and good biocompatibility as indicated by PC12 cell cultures. DLC films fabricated on a Si/SiCx interlayer have high potential as protective coatings for biomedical NiTi materials.

  6. Fuel powder production from ductile uranium alloys.

    SciTech Connect

    Clark, C. R.

    1998-10-23

    Metallic uranium alloys are candidate materials for use as the fuel phase in very-high-density LEU dispersion fuels. These ductile alloys cannot be converted to powder form by the processes routinely used for oxides or intermetallics. Three methods of powder production from uranium alloys have been investigated within the US-RERTR program. These processes are grinding, cryogenic milling, and hydride-dehydride. In addition, a gas atomization process was investigated using gold as a surrogate for uranium. Grinding was found to be inefficient and introduced impurities into the fuel. Cryogenic milling of machine chips in a steel vial was found to have similar shortcomings. The hydride-dehydride process has historically been used to produce very fine powder that may not be suitable for fuel fabrication. Uranium is made to form its hydride by heating in a hydrogen atmosphere. Subsequent heating under vacuum drives off hydrogen gas and returns the hydride to a metallic state. The volume change on hydride formation results in a fine powder upon dehydriding. The effects of alloying elements, partial hydriding, and subsequent milling treatments on particle size distribution are being explored. Inert gas atomization is used on an industrial scale to produce metal powder. Current designs are not suitable for use with uranium. A system was specifically designed for uranium atomization. A prototype was built and tested using gold as a surrogate for uranium. The system operates efficiently and can produce powder in a variety of size ranges by changing the atomization nozzle.

  7. Powder and particulate production of metallic alloys

    NASA Technical Reports Server (NTRS)

    Grant, N. J.

    1982-01-01

    Developments of particulate metallurgy of alloyed materials where the final products is a fully dense body are discussed. Particulates are defined as powders, flakes, foils, silvers, ribbons and strip. Because rapid solidification is an important factor in particulate metallurgy, all of the particulates must have at least one dimension which is very fine, sometimes as fine as 10 to 50 microns, but move typically up to several hundred microns, provided that the dimension permits a minimum solidification rate of at least 100 K/s.

  8. Non-Heat Treatable Alloy Sheet Products

    SciTech Connect

    Hayden, H.W.; Barthold, G.W.; Das, S.K.

    1999-08-01

    ALCAR is an innovative approach for conducting multi-company, pre-competitive research and development programs. ALCAR has been formed to crate a partnership of aluminum producers, the American Society of Mechanical Engineers Center for Research and Technology Development (ASME/CRTD), the United States Department of Energy (USDOE), three USDOE National Laboratories, and a Technical Advisory Committee for conducting cooperative, pre-competitive research on the development of flower-cost, non-heat treated (NHT) aluminum alloys for automotive sheet applications with strength, formability and surface appearance similar to current heat treated (HT) aluminum alloys under consideration. The effort has been supported by the USDOE, Office of Transportation Technology (OTT) through a three-year program with 50/50 cost share at a total program cost of $3 million. The program has led to the development of new and modified 5000 series aluminum ally compositions. Pilot production-size ingots have bee n melted, cast, hot rolled and cold rolled. Stamping trials on samples of rolled product for demonstrating production of typical automotive components have been successful.

  9. REGENERATION OF FISSION-PRODUCT-CONTAINING MAGNESIUM-THORIUM ALLOYS

    DOEpatents

    Chiotti, P.

    1964-02-01

    A process of regenerating a magnesium-thorium alloy contaminated with fission products, protactinium, and uranium is presented. A molten mixture of KCl--LiCl-MgCl/sub 2/ is added to the molten alloy whereby the alkali, alkaline parth, and rare earth fission products (including yttrium) and some of the thorium and uranium are chlorinated and

  10. Space-charge-limited currents: Refinements in analysis and applications to a-Si/sub 1-x/Ge/sub x/:H alloys

    SciTech Connect

    Weisfield, R.L.

    1983-11-01

    A new algorithm is described for deriving the density of states N(E) from the Fermi energy E/sub F/ upwards toward the conduction band edge. This refinement in the analysis of space-charge-limited currents (SCLC) enables the accurate determination of N(E) by implicitly accounting for the spatial variations of physical quantities across the thickness of the diode. SCLC is measured in NiCr/n/sup +//a-Si/sub 1-x/Ge/sub x/:H/Pt diode structures. For a-Si:H samples, SCLC values for N(E/sub F/) are compared to those derived from admittance measurements on the same diodes. The two determinations agree in samples where 10/sup 16/a-Si/sub 0.7/Ge/sub 0.3/:H is also investigated, as a function of hydrogen content c/sub H/, optical gap, and photoluminescence intensity I/sub PL/. In this alloy increasing c/sub H/ causes N(E/sub F/) to decrease, to a minimum of 3 x 10/sup 16/ for c/sub H/ = 14 at. %. I/sub PL/ increases inversely with N(E/sub F/), confirming the sensitivity of SCLC to bulk nonradiative recombination centers.

  11. Rough titanium alloys regulate osteoblast production of angiogenic factors.

    PubMed

    Olivares-Navarrete, Rene; Hyzy, Sharon L; Gittens, Rolando A; Schneider, Jennifer M; Haithcock, David A; Ullrich, Peter F; Slosar, Paul J; Schwartz, Zvi; Boyan, Barbara D

    2013-11-01

    Polyether-ether-ketone (PEEK) and titanium-aluminum-vanadium (titanium alloy) are used frequently in lumbar spine interbody fusion. Osteoblasts cultured on microstructured titanium generate an environment characterized by increased angiogenic factors and factors that inhibit osteoclast activity mediated by integrin α2β1 signaling. It is not known if this is also true of osteoblasts on titanium alloy or PEEK. The purpose of this study was to determine if osteoblasts generate an environment that supports angiogenesis and reduces osteoclastic activity when grown on smooth titanium alloy, rough titanium alloy, or PEEK. This in vitro study compared angiogenic factor production and integrin gene expression of human osteoblast-like MG63 cells cultured on PEEK or titanium-aluminum-vanadium (titanium alloy). MG63 cells were grown on PEEK, smooth titanium alloy, or rough titanium alloy. Osteogenic microenvironment was characterized by secretion of osteoprotegerin and transforming growth factor beta-1 (TGF-β1), which inhibit osteoclast activity and angiogenic factors including vascular endothelial growth factor A (VEGF-A), fibroblast growth factor 2 (FGF-2), and angiopoietin-1 (ANG-1). Expression of integrins, transmembrane extracellular matrix recognition proteins, was measured by real-time polymerase chain reaction. Culture on titanium alloy stimulated osteoprotegerin, TGF-β1, VEGF-A, FGF-2, and angiopoietin-1 production, and levels were greater on rough titanium alloy than on smooth titanium alloy. All factors measured were significantly lower on PEEK than on smooth or rough titanium alloy. Culture on titanium alloy stimulated expression of messenger RNA for integrins that recognize Type I collagen in comparison with PEEK. Rough titanium alloy stimulated cells to create an osteogenic-angiogenic microenvironment. The osteogenic-angiogenic responses to titanium alloy were greater than PEEK and greater on rough titanium alloy than on smooth titanium alloy. Surface

  12. Self-consistent analysis of mobility-lifetime products and subgap absorption on different PECVD a-Si:H films

    SciTech Connect

    Jiao, L.; Semoushikina, S.; Lee, Y.; Wronski, C.R.

    1997-07-01

    The photoconductivity and subband gap absorption measurements over a wide range of generation rate(G) have been carried out on diluted and undiluted a-Si:H. It is found that in these high quality films there are significant differences in the functional dependence of mobility-lifetime ({micro}{tau}) products on G. In addition to the different values of subgap absorption ({alpha}) there are also distinct differences in the dependence of {alpha} on photon energy (E) as well as G. It is difficult to self consistently analyze the results on the undiluted film with the previously used three gaussian distribution, particularly at high generation rates. Self consistent analysis is obtained when the (+/0) transitions of negative charged defects and the (0/{minus}) transitions of positive charged defects are introduced respectively closer to the valence and conduction bands. This new gap state distribution is a better representation for the defect pool model and potential fluctuation model.

  13. Efficiency and throughput advances in continuous roll-to-roll a-Si alloy PV manufacturing technology: Annual technical progress report: 22 June 1998--21 June 1999

    SciTech Connect

    Izu, M.

    1999-11-09

    This document reports on work performed by Energy Conversion Devices, Inc. (ECD) during Phase 1 of this subcontract. During this period, ECD researchers: (1) Completed design and construction of new, improved substrate heater; (2) Tested and verified improved performance of the new substrate heater in the pilot machine; (3) Verified improved performance of the new substrate heater in the production machine; (4) Designed and bench-tested a new infrared temperature sensor; (5) Installed a prototype new infrared temperature sensor in the production machine for evaluation; (6) Designed a new rolling thermocouple temperature sensor; (7) Designed and bench-tested a reflectometer for the backreflector deposition machine; (8) Designed and bench-tested in-line non-contacting cell diagnostic sensor and PV capacitive diagnostic system; (9) Installed the in-line cell diagnostic sensor in the 5-MW a-Si deposition machine for evaluation; (10) Demonstrated a new low-cost zinc metal process in the pilot back reflector machine; and (11) Fully tested a new cathode design for improved uniformity.

  14. Research on the stability, electronic properties, and structure of a-Si:H and its alloys. Annual subcontract report, 1 June 1991--31 May 1992

    SciTech Connect

    Street, R.A.; Jackson, W.B.; Johnson, N.; Nebel, C.; Hack, M.; Santos, P.; Thompson, R.; Tsai, C.C.; Walker, J.

    1992-12-01

    Objective is to obtain a comprehensive understanding of structure and electronic properties of a-Si:H as they apply to solar cells. First observations were of light enhancement and field suppression of H diffusion in a-Si:H. Theoretical studies were made of hydrogen density of states distribution and its relation to defect metastability. Reduced density of light induced defect is observed in a-Si:H deposited in a remote hydrogen plasma reactor at 400 C. Kinetics of metastable defect creation using forward bias in a p-i-n diode to induce defects were studied and compared to light-induced defect creation in the same devices. Studies were made of transport at high electric field and low temperature. Detailed studies were made of kinetics of dopant metastability in n-type and p-type a-Si:H.

  15. Processing and Applications of Depleted Uranium Alloy Products

    DTIC Science & Technology

    1976-09-01

    Content for Uranium Alloys in 10ŗ M KCL. . 33 9 Plane Strain Threshold for Stress Corrosion Crack Propagation for U-0.75 Ti ....... 33 10 Cold- Wall Steel...impurity elements are copper, iron , and nickel primarily from container rust during handling, and such inadvertently included components such as...chemistry shown in Table 2. The major impurity elements in this product are associated with the purity of the UF4 and magnesium, and primarily are iron

  16. Identification of the Chemical Bonding Prompting Adhesion of a-C:H Thin Films on Ferrous Alloy Intermediated by a SiCx:H Buffer Layer.

    PubMed

    Cemin, F; Bim, L T; Leidens, L M; Morales, M; Baumvol, I J R; Alvarez, F; Figueroa, C A

    2015-07-29

    Amorphous carbon (a-C) and several related materials (DLCs) may have ultralow friction coefficients that can be used for saving-energy applications. However, poor chemical bonding of a-C/DLC films on metallic alloys is expected, due to the stability of carbon-carbon bonds. Silicon-based intermediate layers are employed to enhance the adherence of a-C:H films on ferrous alloys, although the role of such buffer layers is not yet fully understood in chemical terms. The chemical bonding of a-C:H thin films on ferrous alloy intermediated by a nanometric SiCx:H buffer layer was analyzed by X-ray photoelectron spectroscopy (XPS). The chemical profile was inspected by glow discharge optical emission spectroscopy (GDOES), and the chemical structure was evaluated by Raman and Fourier transform infrared spectroscopy techniques. The nature of adhesion is discussed by analyzing the chemical bonding at the interfaces of the a-C:H/SiCx:H/ferrous alloy sandwich structure. The adhesion phenomenon is ascribed to specifically chemical bonding character at the buffer layer. Whereas carbon-carbon (C-C) and carbon-silicon (C-Si) bonds are formed at the outermost interface, the innermost interface is constituted mainly by silicon-iron (Si-Fe) bonds. The oxygen presence degrades the adhesion up to totally delaminate the a-C:H thin films. The SiCx:H deposition temperature determines the type of chemical bonding and the amount of oxygen contained in the buffer layer.

  17. Process for continuous production of metallic uranium and uranium alloys

    DOEpatents

    Hayden, H.W. Jr.; Horton, J.A.; Elliott, G.R.B.

    1995-06-06

    A method is described for forming metallic uranium, or a uranium alloy, from uranium oxide in a manner which substantially eliminates the formation of uranium-containing wastes. A source of uranium dioxide is first provided, for example, by reducing uranium trioxide (UO{sub 3}), or any other substantially stable uranium oxide, to form the uranium dioxide (UO{sub 2}). This uranium dioxide is then chlorinated to form uranium tetrachloride (UCl{sub 4}), and the uranium tetrachloride is then reduced to metallic uranium by reacting the uranium chloride with a metal which will form the chloride of the metal. This last step may be carried out in the presence of another metal capable of forming one or more alloys with metallic uranium to thereby lower the melting point of the reduced uranium product. The metal chloride formed during the uranium tetrachloride reduction step may then be reduced in an electrolysis cell to recover and recycle the metal back to the uranium tetrachloride reduction operation and the chlorine gas back to the uranium dioxide chlorination operation. 4 figs.

  18. Process for continuous production of metallic uranium and uranium alloys

    DOEpatents

    Hayden, Jr., Howard W.; Horton, James A.; Elliott, Guy R. B.

    1995-01-01

    A method is described for forming metallic uranium, or a uranium alloy, from uranium oxide in a manner which substantially eliminates the formation of uranium-containing wastes. A source of uranium dioxide is first provided, for example, by reducing uranium trioxide (UO.sub.3), or any other substantially stable uranium oxide, to form the uranium dioxide (UO.sub.2). This uranium dioxide is then chlorinated to form uranium tetrachloride (UCl.sub.4), and the uranium tetrachloride is then reduced to metallic uranium by reacting the uranium chloride with a metal which will form the chloride of the metal. This last step may be carried out in the presence of another metal capable of forming one or more alloys with metallic uranium to thereby lower the melting point of the reduced uranium product. The metal chloride formed during the uranium tetrachloride reduction step may then be reduced in an electrolysis cell to recover and recycle the metal back to the uranium tetrachloride reduction operation and the chlorine gas back to the uranium dioxide chlorination operation.

  19. Dimensional control of quasisingle crystals of aluminum alloy in production

    SciTech Connect

    Radchenko, A.I.; Karuskevich, M.V.; Naim, V.R.

    1995-01-01

    The article deals with a method of controlling the dimensions of quasisingle crystal grains of an aluminum alloy used instead of single crystal specimens in static fatigue tests with the object of substantiating a discrete probabilistic model of the fatigue of metals and alloys. We obtained a mathematical model of dimensional control of quasisingle crystals of the aluminum alloy.

  20. Study of gap states in a-Si:H alloys by measurements of photoconductivity and spectral response of MIS solar cells

    SciTech Connect

    Vanier, P.E.; Delahoy, A.E.; Griffith, R.W.

    1981-01-01

    A picture of the density of gap states n(E) in glow discharge a-Si:H is constructed using four different kinds of transport measurement on a large number of samples. The minimum in n(E) lies 0.4 eV below E/sub c/, rather than in the middle of the gap. A distribution of fast recombination centers lies at mid-gap, and two sets of hole traps lie between mid-gap and the valence band. Modifications in n(E) have been studied by the effects of selected impurities on the conversion efficiency and spectral response of MIS and p-i-n solar cells.

  1. Post-annealing effects on the electrochemical performance of a Si/TiSi2 heteronanostructured anode material prepared by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Shin, Min-Seon; Lee, Taeg-Woo; Park, Jung-Bae; Lim, Sung-Hwan; Lee, Sung-Man

    2017-03-01

    A change in the microstructure of Ti-Si alloys synthesized by high-energy mechanical milling through post-annealing significantly enhances their electrochemical performances as anode materials for lithium-ion batteries (LIBs). The microstructures of ball-milled and post-annealed powders are investigated using high-resolution transmission electron microscopy (HR-TEM). The Si phase is uniformly distributed on the silicide (TiSi2) matrix. The individual Si domains of the mechanical alloying (MA) sample consist of amorphous and crystalline regions with a diffuse interface between the two phases. When MA powder is annealed at 600 °C, the Si phase has a well-developed nanocrystalline microstructure: a multi-grain structure with random orientation of nanometric crystal domains. Annealing at 600 °C causes a significant improvement in electrochemical performance parameters like cycling stability and rate capability. However, when annealed at 800 °C, the electrochemical performances deteriorate due to an increase in the size of Si domains.

  2. Investigation of the radiation resistance of triple-junction a-Si:H alloy solar cells irradiated with 1.00 MeV protons

    NASA Technical Reports Server (NTRS)

    Lord, Kenneth R., II; Walters, Michael R.; Woodyard, James R.

    1993-01-01

    The effect of 1.00 MeV proton irradiation on hydrogenated amorphous silicon alloy triple-junction solar cells is reported for the first time. The cells were designed for radiation resistance studies and included 0.35 cm(sup 2) active areas on 1.0 by 2.0 cm(sup 2) glass superstrates. Three cells were irradiated through the bottom contact at each of six fluences between 5.10E12 and 1.46E15 cm(sup -2). The effect of the irradiations was determined with light current-voltage measurements. Proton irradiation degraded the cell power densities from 8.0 to 98 percent for the fluences investigated. Annealing irradiated cells at 200 C for two hours restored the power densities to better than 90 percent. The cells exhibited radiation resistances which are superior to cells reported in the literature for fluences less than 1E14 cm(sup -2).

  3. The effects of a SiO2 coating on the corrosion parameters cpTi and Ti-6Al-7Nb alloy.

    PubMed

    Basiaga, Marcin; Walke, Witold; Paszenda, Zbigniew; Karasiński, Paweł; Szewczenko, Janusz

    2014-01-01

    The aim of this paper was to evaluate the usefulness of the sol-gel method application, to modificate the surface of the Ti6Al7Nb alloy and the cpTi titanium (Grade 4) with SiO2 oxide, applied on the vascular implants to improve their hemocompatibility. Mechanical treatment was followed by film deposition on surface of the titanium samples. An appropriate selection of the process parameters was verified in the studies of corrosion, using potentiodynamic and impedance method. A test was conducted in the solution simulating blood vessels environment, in simulated body fluid at t = 37.0 ± 1 °C and pH = 7.0 ± 0.2. Results showed varied electrochemical properties of the SiO2 film, depending on its deposition parameters. Correlations between corrosion resistance and layer adhesion to the substrate were observed, depending on annealing temperature.

  4. The effects of a SiO2 coating on the corrosion parameters cpTi and Ti-6Al-7Nb alloy

    PubMed Central

    Basiaga, Marcin; Walke, Witold; Paszenda, Zbigniew; Karasiński, Paweł; Szewczenko, Janusz

    2014-01-01

    The aim of this paper was to evaluate the usefulness of the sol-gel method application, to modificate the surface of the Ti6Al7Nb alloy and the cpTi titanium (Grade 4) with SiO2 oxide, applied on the vascular implants to improve their hemocompatibility. Mechanical treatment was followed by film deposition on surface of the titanium samples. An appropriate selection of the process parameters was verified in the studies of corrosion, using potentiodynamic and impedance method. A test was conducted in the solution simulating blood vessels environment, in simulated body fluid at t = 37.0 ± 1 °C and pH = 7.0 ± 0.2. Results showed varied electrochemical properties of the SiO2 film, depending on its deposition parameters. Correlations between corrosion resistance and layer adhesion to the substrate were observed, depending on annealing temperature. PMID:25482412

  5. Atomic scale modelling of hexagonal structured metallic fission product alloys

    PubMed Central

    Middleburgh, S. C.; King, D. M.; Lumpkin, G. R.

    2015-01-01

    Noble metal particles in the Mo-Pd-Rh-Ru-Tc system have been simulated on the atomic scale using density functional theory techniques for the first time. The composition and behaviour of the epsilon phases are consistent with high-entropy alloys (or multi-principal component alloys)—making the epsilon phase the only hexagonally close packed high-entropy alloy currently described. Configurational entropy effects were considered to predict the stability of the alloys with increasing temperatures. The variation of Mo content was modelled to understand the change in alloy structure and behaviour with fuel burnup (Mo molar content decreases in these alloys as burnup increases). The predicted structures compare extremely well with experimentally ascertained values. Vacancy formation energies and the behaviour of extrinsic defects (including iodine and xenon) in the epsilon phase were also investigated to further understand the impact that the metallic precipitates have on fuel performance. PMID:26064629

  6. Atomic scale modelling of hexagonal structured metallic fission product alloys.

    PubMed

    Middleburgh, S C; King, D M; Lumpkin, G R

    2015-04-01

    Noble metal particles in the Mo-Pd-Rh-Ru-Tc system have been simulated on the atomic scale using density functional theory techniques for the first time. The composition and behaviour of the epsilon phases are consistent with high-entropy alloys (or multi-principal component alloys)-making the epsilon phase the only hexagonally close packed high-entropy alloy currently described. Configurational entropy effects were considered to predict the stability of the alloys with increasing temperatures. The variation of Mo content was modelled to understand the change in alloy structure and behaviour with fuel burnup (Mo molar content decreases in these alloys as burnup increases). The predicted structures compare extremely well with experimentally ascertained values. Vacancy formation energies and the behaviour of extrinsic defects (including iodine and xenon) in the epsilon phase were also investigated to further understand the impact that the metallic precipitates have on fuel performance.

  7. Production of FR Tubing from Advanced ODS Alloys

    SciTech Connect

    Maloy, Stuart Andrew; Lavender, Curt; Omberg, Ron; Lewandowski, John

    2016-10-25

    Significant research is underway to develop LWR nuclear fuels with improved accident tolerance. One of the leading candidate materials for cladding are the FeCrAl alloys. New alloys produced at ORNL called Gen I and Gen II FeCrAl alloys possess excellent oxidation resistance in steam up to 1400°C and in parallel methods are being developed to produce tubing from these alloys. Century tubing continues to produce excellent tubing from FeCrAl alloys. This memo reports receipt of ~21 feet of Gen I FeCrAl alloy tubing. This tubing will be used for future tests including burst testing, mechanical testing and irradiation testing.

  8. Production of Cu-Al-Ni Shape Memory Alloys by Mechanical Alloy

    SciTech Connect

    Goegebakan, Musa; Soguksu, Ali Kemal; Uzun, Orhan; Dogan, Ali

    2007-04-23

    The mechanical alloying technique has been used to produce shape memory Cu83Al13Ni4 alloy. The structure and thermal properties were examined by using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The morphology of the surface suggests the presence of martensite.

  9. Thermal Exposure Effects on Properties of Al-Li Alloy Plate Products

    NASA Technical Reports Server (NTRS)

    Shah, Sandeep; Wells, Douglas; Wagner, John; Babel, Henry

    2003-01-01

    The objective of this viewgraph representation is to evaluate the effects of thermal exposure on the mechanical properties of both production mature and developmental Al-Li alloys. The researchers find for these alloys, the data clearly shows that there is no deficit in mechanical properties at lower exposure temperatures in some cases, and a signficant deficit in mechanical properties at higher exposure temperatures in all cases. Topics considered include: Al-Li alloys composition, key characteristics of Al-Li alloys and thermal exposure matrix.

  10. Thermal Exposure Effects on Properties of Al-Li Alloy Plate Products

    NASA Technical Reports Server (NTRS)

    Shah, Sandeep; Wells, Douglas; Wagner, John; Babel, Henry

    2003-01-01

    The objective of this viewgraph representation is to evaluate the effects of thermal exposure on the mechanical properties of both production mature and developmental Al-Li alloys. The researchers find for these alloys, the data clearly shows that there is no deficit in mechanical properties at lower exposure temperatures in some cases, and a signficant deficit in mechanical properties at higher exposure temperatures in all cases. Topics considered include: Al-Li alloys composition, key characteristics of Al-Li alloys and thermal exposure matrix.

  11. Welding of NOREM iron-base hardfacing alloy wire products: Procedures for gas tungsten arc welding

    SciTech Connect

    Phillps, M.K.; Findlan, S.J. . Nondestructive Evaluation Center)

    1992-09-01

    New wire products have been successfully fabricated and procedures developed for automatic gas tungsten arc welding of wear-resistant NOREM iron-base alloys. Research demonstrated that sound multilayer welds on carbon and stainless steel substrates can be obtained without the use of preheating. These developments point to the advantages of NOREM alloys for field applications, such as valve refurbishing.

  12. Spiked Alloy Production for Accelerated Aging of Plutonium

    SciTech Connect

    Wilk, P A; McNeese, J A; Dodson, K E; Williams, W L; Krikorian, O H; Blau, M S; Schmitz, J E; Bajao, F G; Mew, D A; Matz, T E; Torres, R A; Holck, D M; Moody, K J; Kenneally, J M

    2009-07-10

    The accelerated aging effects on weapons grade plutonium alloys are being studied using {sup 238}Pu-enriched plutonium metal to increase the rate of formation of defect structures. Pyrochemical processing methods have been used to produce two {sup 238}Pu-spiked plutonium alloys with nominal compositions of 7.5 wt% {sup 238}Pu. Processes used in the preparation of the alloys include direct oxide reduction of PuO{sub 2} with calcium and electrorefining. Rolled disks were prepared from the spiked alloys for sampling. Test specimens were cut out of the disks for physical property measurements.

  13. Characterization of simulated production welds in alloy 908

    SciTech Connect

    Jang, C.H.; Grundy, D.C.; Steeves, M.M.

    1997-06-01

    This study characterized room temperature mechanical properties of Incoloy{reg_sign} alloy 908* welds made from two base metal conditions: mill-annealed or homogenized (1050{degrees}C/1hr). An automatic pulsed-gas tungsten arc welder simulated actual conduit welding conditions. The weld fusion zone showed a typical cellular-dendritic microstructure with the precipitation of secondary phases within the interdendritic zone. Grain boundary liquation phenomenon was observed near the fusion boundaries in the heat affected zone. Complete resolidification of liquated grain boundaries prevented crack formation during welding. The tensile properties of the welds showed a strong dependence on the selection of the base metal used for welding. When the base metal was homogenized, the welds showed about the same amount of ductility as the homogenized base metal in the as-welded condition. Its strength was also higher than that of the surrounding homogenized base metal. The fracture toughness of welds was measured by the J-integral test technique. Unlike the tensile properties, the fracture toughness of the welds showed no dependence on the condition of the base metal. The fracture toughness of the welds was about 140 MPa{radical}m in the aged condition. The fatigue crack growth rates of aged production welds were comparable to those of the base metal. The fatigue crack growth threshold was measured to be about 3.7 MPa{radical}m for the as-welded production welds with homogenized base metal.

  14. Formation of the structure of thin-sheet rolled product from a high-strength sparingly alloyed aluminum alloy ``nikalin''

    NASA Astrophysics Data System (ADS)

    Shurkin, P. K.; Belov, N. A.; Akopyan, T. K.; Alabin, A. N.; Aleshchenko, A. S.; Avxentieva, N. N.

    2017-09-01

    The regime of thermomechanical treatment of flat ingots of a high-strength sparingly alloyed alloy based on the Al-Zn-Mg-Ni-Fe system upon the production of thin-sheet rolled products with a reduction of more than 97% has been substantiated. Using experimental and calculated methods, the structure and phase composition of the experimental alloy in the as cast and deformed state and after heat treatment including quenching with subsequent aging have been studied. It has been found that the structure of the wrought semi-finished products after aging according to T and T1 regimes consists of the precipitation-hardened aluminum matrix and uniformly distributed isolated particles of Al9FeNi with a size of 1-2 μm, which provides a combination of high strength and satisfactory plasticity at the level of standard high-strength aluminum alloys of the Al-Zn-Mg-Cu system. The fractographic analysis confirmed that the tested samples underwent a ductile fracture.

  15. Selecting copper and copper alloys; Part 2: Cast products

    SciTech Connect

    Peters, D.T. ); Kundig, K.J.A. , Randolph, NJ )

    1994-06-01

    This article provides an introduction to the properties, characteristics, and applications of cast coppers and copper alloys. An overview of alloy families is presented since it is impractical to describe all 130 standard grades in detail. However, additional technical information is readily available from the Copper Development Assn. Inc. (CDA) and the resources listed in the references and bibliography at the end of the article. Copper casting alloys are primarily selected for either their corrosion resistance, or their combination of corrosion resistance and mechanical properties. The materials also feature good castability, high machinability, and, compared with other corrosion-resistant alloys, reasonable cost. Additional benefits include biofouling resistance--important in marine applications--and a spectrum of attractive colors. Many of the alloys also have favorable tribological properties, which explains their widespread use for sleeve bearings, wear plates, gears, and other wear-prone components.

  16. Plate-shaped transformation products in zirconium-base alloys

    NASA Astrophysics Data System (ADS)

    Banerjee, S.; Dey, G. K.; Srivastava, D.; Ranganathan, S.

    1997-11-01

    Plate-shaped products resulting from martensitic, diffusional, and mixed mode transformations in zirconium-base alloys are compared in the present study. These alloys are particularly suitable for the comparison in view of the fact that the lattice correspondence between the parent β (bcc) and the product α (hcp) or γ-hydride (fct) phases are remarkably similar for different types of transformations. Crystallographic features such as orientation relations, habit planes, and interface structures associated with these transformations have been compared, with a view toward examining whether the transformation mechanisms have characteristic imprints on these experimental observables. Martensites exhibiting dislocated lath, internally twinned plate, and self-accommodating three-plate cluster morphologies have been encountered in Zr-2.5Nb alloy. Habit planes corresponding to all these morphologies have been found to be consistent with the predictions based on the invariant plane strain (IPS) criterion. Different morphologies have been found to reflect the manner in which the neighboring martensite variants are assembled. Lattice-invariant shears (LISs) for all these cases have been identified to be either {10 bar 11} α < bar 1123> α slip or twinning on {10 bar 11} α planes. Widmanstätten α precipitates, forming in a step-quenching treatment, have been shown to have a lath morphology, the α/β interface being decorated with a periodic array of < c + a> dislocations at a spacing of 8 to 10 nm. The line vectors of these dislocations are nearly parallel to the invariant lines. The α precipitates, forming in the retained β phase on aging, exhibit an internally twinned structure with a zigzag habit plane. Average habit planes for the morphologies have been found to lie near the {103} β — {113} β poles, which are close to the specific variant of the {112} β plane, which transforms into a prismatic plane of the type {1 bar 100} α . The crystallography of the

  17. Ni-Si Alloys for the S-I Reactor-Hydrogen Production Process Interface

    SciTech Connect

    Joseph W. Newkirk; Richard K. Brow

    2010-01-21

    The overall goal of this project was to develop Ni-Si alloys for use in vessels to contain hot, pressurized sulfuric acid. The application was to be in the decomposition loop of the thermochemical cycle for production of hydrogen.

  18. [MEDICAL AND PREVENTIVE MEASURES FOR REDUCING CHEMICAL OCCUPATIONAL RISKS IN THE PRODUCTION OF TITANIUM ALLOYS].

    PubMed

    Bazarova, E L; Osherov, I S; Roslyĭ, O F; Tartakovskaia, L Ia

    2015-01-01

    An innovative approach in the prevention and rehabilitation of workers employed in the production of titanium alloys envisages the implementation of targeted multi-stage rehabilitation measures in groups with high occupational risk.

  19. Process for making a martensitic steel alloy fuel cladding product

    DOEpatents

    Johnson, Gerald D.; Lobsinger, Ralph J.; Hamilton, Margaret L.; Gelles, David S.

    1990-01-01

    This is a very narrowly defined martensitic steel alloy fuel cladding material for liquid metal cooled reactors, and a process for making such a martensitic steel alloy material. The alloy contains about 10.6 wt. % chromium, about 1.5 wt. % molybdenum, about 0.85 wt. % manganese, about 0.2 wt. % niobium, about 0.37 wt. % silicon, about 0.2 wt. % carbon, about 0.2 wt. % vanadium, 0.05 maximum wt. % nickel, about 0.015 wt. % nitrogen, about 0.015 wt. % sulfur, about 0.05 wt. % copper, about 0.007 wt. % boron, about 0.007 wt. % phosphorous, and with the remainder being essentially iron. The process utilizes preparing such an alloy and homogenizing said alloy at about 1000.degree. C. for 16 hours; annealing said homogenized alloy at 1150.degree. C. for 15 minutes; and tempering said annealed alloy at 700.degree. C. for 2 hours. The material exhibits good high temperature strength (especially long stress rupture life) at elevated temperature (500.degree.-760.degree. C.).

  20. Sintered rare earth-iron Laves phase magnetostrictive alloy product and preparation thereof

    DOEpatents

    Malekzadeh, Manoochehr; Pickus, Milton R.

    1979-01-01

    A sintered rare earth-iron Laves phase magnetostrictive alloy product characterized by a grain oriented morphology. The grain oriented morphology is obtained by magnetically aligning powder particles of the magnetostrictive alloy prior to sintering. Specifically disclosed are grain oriented sintered compacts of Tb.sub.x Dy.sub.1-x Fe.sub.2 and their method of preparation. The present sintered products have enhanced magnetostrictive properties.

  1. Production and fabrication of vanadium alloys for the radiative divertor program of DIII-D

    SciTech Connect

    Johnson, W.R.; Smith, J.P.; Stambaugh, R.D.

    1996-04-01

    V-4Cr-4-Ti alloy has been recently selected for use in the manufacture of a portion of the DIII-D Radiative Divertor modification, as part of an overall DIII-D vanadium alloy deployment effort developed by General Atomics (GA) in conjunction with the Argonne and Oak Ridge National Laboratories (ANL or ORNL). The goal of this work is to produce a production-scale heat of the alloy and fabricate it into product forms for the manufacture of a portion of the Radiative Divertor (RD) for the DIII-D tokamak, to develop the fabrications technology for manufacture of the vanadium alloy radiative Divertor components, and to determine the effects of typical tokamak environments in the behavior of the vanadium alloy. The production of a {approx}1300-kg heat of V-4Cr-4Ti alloy is currently in progress at Teledyne Wah Chang of Albany, oregon (TWCA) to provide sufficient material for applicable product forms. Two unalloyed vanadium ingots for the alloy have already been produced by electron beam melting of raw processes vanadium. Chemical compositions of one ingot and a portion of the second were acceptable, and Charpy V-Notch (CVN) impact test performed on processed ingot samples indicated ductile behavior. Material from these ingots are currently being blended with chromium and titanium additions, and will be vacuum-arc remelted into a V-4Cr-4Ti alloy ingot and converted into product forms suitable for components of the DIII-D RD structure. Several joining methods selected for specific applications in fabrication of the RD components are being investigated, and preliminary trials have been successful in the joining of V-alloy to itself by both resistance and inertial welding processes and to Inconel 625 by inertial welding.

  2. Production and fabrication of vanadium alloys for the radiative divertor program of DIII-D

    SciTech Connect

    Johnson, W.R.; Smith, J.P.; Trester, P.W.

    1997-04-01

    V-4Cr-4Ti alloy has been selected for use in the manufacture of a portion of the DIII-D Radiative Divertor upgrade. The production of a 1200-kg ingot of V-4Cr-4Ti alloy, and processing into final sheet and rod product forms suitable for components of the DIII-D Radiative Divertor structure, has been completed at Wah Chang (formerly Teledyne Wah Chang) of Albany, Oregon (WCA). Joining of V-4Cr-4Ti alloy has been identified as the most critical fabrication issue for its use in the RD Program, and research into several joining methods for fabrication of the RD components, including resistance seam, friction, and electron beam welding, is continuing. Preliminary trials have been successful in the joining of V-alloy to itself by electron beam, resistance, and friction welding processes, and to Inconel 625 by friction welding. An effort to investigate the explosive bonding of V-4Cr-4Ti alloy to Inconel 625 has also been initiated, and results have been encouraging. In addition, preliminary tests have been completed to evaluate the susceptibility of V-4Cr-4Ti alloy to stress corrosion cracking in DIII-D cooling water, and the effects of exposure to DIII-D bakeout conditions on the tensile and fracture behavior of V-4Cr-4Ti alloy.

  3. Increasing the reliability and quality of important cast products made of chemically active metals and alloys

    NASA Astrophysics Data System (ADS)

    Varfolomeev, M. S.; Moiseev, V. S.; Shcherbakova, G. I.

    2017-01-01

    A technology is developed to produce highly thermoresistant ceramic monoxide corundum molds using investment casting and an aluminum-organic binder. This technology is a promising trend in creating ceramic molds for precision complex-shape casting of important ingots made of high-alloy steels, high-temperature and titanium alloys, and refractory metals. The use of the casting molds that have a high thermal and chemical resistance to chemically active metals and alloys under high-temperature casting minimizes the physicochemical interaction and substantially decreases the depth of the hard-to-remove metal oxide layer on important products, which increases their service properties.

  4. [Using Raman spectrum analysis to research corrosive productions occurring in alloy of ancient bronze wares].

    PubMed

    Jia, La-jiang; Jin, Pu-jun

    2015-01-01

    The present paper analyzes the interior rust that occurred in bronze alloy sample from 24 pieces of Early Qin bronze wares. Firstly, samples were processed by grinding, polishing and ultrasonic cleaning-to make a mirror surface. Then, a confocal micro-Raman spectrometer was employed to carry out spectroscopic study on the inclusions in samples. The conclusion indicated that corrosive phases are PbCO3 , PbO and Cu2O, which are common rusting production on bronze alloy. The light-colored circular or massive irregular areas in metallographic structure of samples are proved as Cu2O, showing that bronze wares are not only easy to be covered with red Cu2O rusting layer, but also their alloy is easy to be eroded by atomic oxygen. In other words, the rust Cu2O takes place in both the interior and exterior parts of the bronze alloy. In addition, Raman spectrum analysis shows that the dark grey materials are lead corrosive products--PbCO3 and PbO, showing the corroding process of lead element as Pb -->PbO-->PbCO3. In the texture of cast state of bronze alloy, lead is usually distributed as independent particles between the different alloy phases. The lead particles in bronze alloy would have oxidation reaction and generate PbO when buried in the soil, and then have chemical reaction with CO3(2-) dissolved in the underground water to generate PbCO3, which is a rather stable lead corrosive production. A conclusion can be drawn that the external corrosive factors (water, dissolved oxygen and carbonate, etc) can enter the bronze ware interior through the passageway between different phases and make the alloy to corrode gradually.

  5. Laser forming of structures of zinc oxide on a surface of products from copper alloys

    NASA Astrophysics Data System (ADS)

    Abramov, D. V.; Gorudko, T. N.; Koblov, A. N.; Nogtev, D. S.; Novikova, O. A.

    Laser formation of a protective zinc oxide layer on a surface of products from copper alloys is present. This layer is formed with using of carbon nanotubes. Destructions of the basic material are avoided or minimized at laser nanostructuring of product surfaces. Such laser processing can be made repeatedly. Offered covering have self-clearing and water-repellent properties.

  6. Production and fabrication of vanadium alloys for the radiative divertor program of DIII-D

    SciTech Connect

    Johnson, W.R.; Smith, J.P.

    1997-08-01

    V-4Cr-4Ti alloy has been selected for use in the manufacture of a portion of the DIII-D Radiative Divertor upgrade. The production of a 1200-kg ingot of V-4Cr-4Ti alloy, and processing into final sheet and rod product forms suitable for components of the DIII-D Radiative Divertor Program (RDP), has been completed by Wah Chang (formerly Teledyne Wah Chang) of Albany, Oregon (WCA). CVN impact tests on sheet material indicate that the material has properties comparable to other previously-processed V-4Cr-4Ti and V-5Cr-5Ti alloys. Joining of V-4Cr-4Ti alloy has been identified as the most critical fabrication issue for its use in the RDP, and research into several joining methods for fabrication of the RDP components, including resistance seam, friction, and electron beam welding, and explosive bonding is being pursued. Preliminary trials have been successful in the joining of V-alloy to itself by resistance, friction, and electron beam welding processes, and to Inconel 625 by friction welding. In addition, an effort to investigate the explosive bonding of V-4Cr-4Ti alloy to Inconel 625, in both tube-to-bar and sheet-to-sheet configurations, has been initiated, and results have been encouraging.

  7. Oxidation and volatilization of a niobium alloy. Fusion Safety Program/Activation Products Task

    SciTech Connect

    Smolik, G.R.; McCarthy, K.A.

    1992-07-01

    This report presents the findings from a preliminary investigation into oxidation and volatilization characteristics of a niobium alloy. Niobium is a candidate alloy for use in plasma facing components (PFCS) in experimental fusion reactors like the Intemational Thermonuclear Experimental Reactor (ITER). An experimental alloy was tailored to simulate small changes in chemistry which could result from transmutations from irradiation. The alloy was exposed in air and steam between 800{degree}C and 1200{degree}C. Volatilized products and hydrogen were collected and measured. Post-test examinations were also performed on the samples to determine the amount of material loss during the exposures. The obtained measurements of volatilization flux (g/m{sup 2}-s), hydrogen generation rates (liters/m{sup 2}-s), and recession rates (mm/s) are data which can be used for safety analyses and material performance to predict consequences which may result from an accident involving the ingress of air or steam into the plasma chamber of fusion reactor. In our volatility tests, only molybdenum and niobium were found at release levels above the detection limit. Although molybdenum is present at only 0.12 wt%, the quantities of this element volatilized in air are nearly comparable to the quantities of niobium released. The niobium release in steam is only three to four times higher than that of molybdenum in steam. The hydrogen production of the niobium alloy is compared with other PFC materials that we have tested, specifically, beryllium, graphite, and a tunesten alloy. At high temperatures, the hydrogen production rate of the niobium alloy is among the lowest of these materials, significantly lower than beryllium. To understand what this means in an accident situation, modeling is necessary to predict temperatures, and therefore total hydrogen production. The INEL is currently doing this modeling.

  8. Development of alloy 718 tubular product for nuclear reactor internals

    SciTech Connect

    1981-01-01

    The Upper Internals Structure (UIS) of the Clinch River Breeder Reactor Plant (CRBRP) provides mixing and flow direction of the core outlet flow. Alloy 718 tubes are the major components used in the UIS to provide this flow direction. The UIS is located directly above the reactor core and is exposed to a severe environment. This environment consists of high temperature sodium, alternating temperatures induced by mixing high temperature core assembly outlet flow with cooler core assembly outlet flow and rapid changes in temperature of the core outlet flow. The paper presents the UIS configuration, functions and environmental conditions that led to the selection of Alloy 718 as the material used to protect the basic UIS structure and to provide flow direction. The paper describes the tube fabrication process, the development of a finish sanding procedure and the results of high temperature thermal cycle testing.

  9. Production of Ni100-x-yMnxGay magnetic shape memory alloys by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Hatchard, T. D.; Thorne, J. S.; Farrell, S. P.; Dunlap, R. A.

    2008-11-01

    Powdered samples of a variety of compositions of the off-stoichiometric magnetic shape memory alloy Ni2MnGa have been prepared by mechanical alloying from elemental precursors. As-milled powders are highly disordered and show very weak ferromagnetic order. Annealing produces a well-ordered L21 Heusler phase with high saturation magnetization. Annealing results in a consistent loss of Ga of about 1-4 at.% (of total sample composition). Structural and magnetic properties of a range of compositions have been measured and are reported in the present work. A magnetically oriented metal-polymer composite has been prepared by mixing the powdered sample in epoxy and curing under an externally applied magnetic field. The magnetic anisotropy energy of the composite sample has been measured and found to be about 20% of the value expected for a single crystal of similar composition. Possibilities for increasing the magnetic anisotropy of metal-polymer composites are discussed. Results are discussed in terms of the effects of structural and chemical order on the resulting magnetic properties in the context of a model based on indirect exchange interactions.

  10. Production Of Tandem Amorphous Silicon Alloy Solar Cells In A Continuous Roll-To-Roll Process

    NASA Astrophysics Data System (ADS)

    Izu, Masat; Ovshinsky, Stanford R.

    1983-09-01

    A roll-to-roll plasma deposition machine for depositing multi-layered amorphous alloys has been developed. The plasma deposition machine (approximately 35 ft. long) has multiple deposition areas and processes 16-inch wide stainless steel substrate continuously. Amorphous photovoltaic thin films (less than 1pm) having a six layered structure (PINPIN) are deposited on a roll of 16-inch wide 1000 ft. long stainless steel substrate, continu-ously, in a single pass. Mass production of low-cost tandem amorphous solar cells utilizing roll-to-roll processes is now possible. A commercial plant utilizing this plasma deposition machine for manufacturing tandem amorphous silicon alloy solar cells is now in operation. At Energy Conversion Devices, Inc. (ECD), one of the major tasks of the photovoltaic group has been the scale-up of the plasma deposition process for the production of amorphous silicon alloy solar cells. Our object has been to develop the most cost effective way of producing amorphous silicon alloy solar cells having the highest efficiency. The amorphous silicon alloy solar cell which we produce has the following layer structure: 1. Thin steel substrate. 2. Multi-layered photovoltaic amorphous silicon alloy layers (approximately 1pm thick; tandem cells have six layers). 3. ITO. 4. Grid pattern. 5. Encapsulant. The deposition of the amorphous layer is technologically the key process. It was clear to us from the beginning of this scale-up program that amorphous silicon alloy solar cells produced in wide width, continuous roll-to-roll production process would be ultimate lowest cost solar cells according to the following reasons. First of all, the material cost of our solar cells is low because: (1) the total thickness of active material is less than 1pm, and the material usage is very small; (2) silicon, fluorine, hydrogen, and other materials used in the device are abundant and low cost; (3) thin, low-cost substrate is used; and (4) product yield is high. In

  11. Cerium-based, intermetallic-strengthened aluminum casting alloy: High-volume co-product development

    DOE PAGES

    Sims, Zachary C.; Weiss, David; McCall, S. K.; ...

    2016-05-23

    Here, several rare earth elements are considered by-products to rare earth mining efforts. By using one of these by-product elements in a high-volume application such as aluminum casting alloys, the supply of more valuable rare earths can be globally stabilized. Stabilizing the global rare earth market will decrease the long-term criticality of other rare earth elements. The low demand for Ce, the most abundant rare earth, contributes to the instability of rare earth extraction. In this article, we discuss a series of intermetallic-strengthened Al alloys that exhibit the potential for new high-volume use of Ce. The castability, structure, and mechanicalmore » properties of binary, ternary, and quaternary Al-Ce based alloys are discussed. We have determined Al-Ce based alloys to be highly castable across a broad range of compositions. Nanoscale intermetallics dominate the microstructure and are the theorized source of the high ductility. In addition, room-temperature physical properties appear to be competitive with existing aluminum alloys with extended high-temperature stability of the nanostructured intermetallic.« less

  12. Cerium-based, intermetallic-strengthened aluminum casting alloy: High-volume co-product development

    SciTech Connect

    Sims, Zachary C.; Weiss, David; McCall, S. K.; McGuire, Michael A.; Ott, Ryan T.; Geer, Tom; Rios, Orlando; Turchi, P. A. E.

    2016-05-23

    Here, several rare earth elements are considered by-products to rare earth mining efforts. By using one of these by-product elements in a high-volume application such as aluminum casting alloys, the supply of more valuable rare earths can be globally stabilized. Stabilizing the global rare earth market will decrease the long-term criticality of other rare earth elements. The low demand for Ce, the most abundant rare earth, contributes to the instability of rare earth extraction. In this article, we discuss a series of intermetallic-strengthened Al alloys that exhibit the potential for new high-volume use of Ce. The castability, structure, and mechanical properties of binary, ternary, and quaternary Al-Ce based alloys are discussed. We have determined Al-Ce based alloys to be highly castable across a broad range of compositions. Nanoscale intermetallics dominate the microstructure and are the theorized source of the high ductility. In addition, room-temperature physical properties appear to be competitive with existing aluminum alloys with extended high-temperature stability of the nanostructured intermetallic.

  13. Cerium-Based, Intermetallic-Strengthened Aluminum Casting Alloy: High-Volume Co-product Development

    NASA Astrophysics Data System (ADS)

    Sims, Zachary C.; Weiss, D.; McCall, S. K.; McGuire, M. A.; Ott, R. T.; Geer, Tom; Rios, Orlando; Turchi, P. A. E.

    2016-07-01

    Several rare earth elements are considered by-products to rare earth mining efforts. By using one of these by-product elements in a high-volume application such as aluminum casting alloys, the supply of more valuable rare earths can be globally stabilized. Stabilizing the global rare earth market will decrease the long-term criticality of other rare earth elements. The low demand for Ce, the most abundant rare earth, contributes to the instability of rare earth extraction. In this article, we discuss a series of intermetallic-strengthened Al alloys that exhibit the potential for new high-volume use of Ce. The castability, structure, and mechanical properties of binary, ternary, and quaternary Al-Ce based alloys are discussed. We have determined Al-Ce based alloys to be highly castable across a broad range of compositions. Nanoscale intermetallics dominate the microstructure and are the theorized source of the high ductility. In addition, room-temperature physical properties appear to be competitive with existing aluminum alloys with extended high-temperature stability of the nanostructured intermetallic.

  14. Cerium-based, intermetallic-strengthened aluminum casting alloy: High-volume co-product development

    SciTech Connect

    Sims, Zachary C.; Weiss, David; McCall, S. K.; McGuire, Michael A.; Ott, Ryan T.; Geer, Tom; Rios, Orlando; Turchi, P. A. E.

    2016-05-23

    Here, several rare earth elements are considered by-products to rare earth mining efforts. By using one of these by-product elements in a high-volume application such as aluminum casting alloys, the supply of more valuable rare earths can be globally stabilized. Stabilizing the global rare earth market will decrease the long-term criticality of other rare earth elements. The low demand for Ce, the most abundant rare earth, contributes to the instability of rare earth extraction. In this article, we discuss a series of intermetallic-strengthened Al alloys that exhibit the potential for new high-volume use of Ce. The castability, structure, and mechanical properties of binary, ternary, and quaternary Al-Ce based alloys are discussed. We have determined Al-Ce based alloys to be highly castable across a broad range of compositions. Nanoscale intermetallics dominate the microstructure and are the theorized source of the high ductility. In addition, room-temperature physical properties appear to be competitive with existing aluminum alloys with extended high-temperature stability of the nanostructured intermetallic.

  15. Cerium-based, intermetallic-strengthened aluminum casting alloy: High-volume co-product development

    DOE PAGES

    Sims, Zachary C.; Weiss, David; McCall, S. K.; ...

    2016-05-23

    Here, several rare earth elements are considered by-products to rare earth mining efforts. By using one of these by-product elements in a high-volume application such as aluminum casting alloys, the supply of more valuable rare earths can be globally stabilized. Stabilizing the global rare earth market will decrease the long-term criticality of other rare earth elements. The low demand for Ce, the most abundant rare earth, contributes to the instability of rare earth extraction. In this article, we discuss a series of intermetallic-strengthened Al alloys that exhibit the potential for new high-volume use of Ce. The castability, structure, and mechanicalmore » properties of binary, ternary, and quaternary Al-Ce based alloys are discussed. We have determined Al-Ce based alloys to be highly castable across a broad range of compositions. Nanoscale intermetallics dominate the microstructure and are the theorized source of the high ductility. In addition, room-temperature physical properties appear to be competitive with existing aluminum alloys with extended high-temperature stability of the nanostructured intermetallic.« less

  16. oxide and FeNi alloy: product dependence on the reduction ability

    NASA Astrophysics Data System (ADS)

    Cao, Jungang; Qin, Yuyang; Li, Minglun; Zhao, Shuyuan; Li, Jianjun

    2014-12-01

    Based on the sol-gel combustion method, stoichiometric Fe3+, Mn2+, Ni2+ ions and citric acid were chosen as the initial reactants for the preparation of magnetic particles. Due to the different reduction ability of metal ions, completely different magnetic products (MnFe2O4 oxide and FeNi alloy) were obtained by heating the flakes at 600 °C under nitrogen atmosphere. MnFe2O4 particles exhibit superparamagnetic behavior at room temperature, and martensitic phase transformation is observed magnetically at 125 K for FeNi alloy particles.

  17. Protection of temperature sensitive biomedical products using molecular alloys as phase change material.

    PubMed

    Mondieig, Denise; Rajabalee, Fazil; Laprie, Alain; Oonk, Harry A J; Calvet, Thereza; Cuevas-Diarte, Miguel Angel

    2003-04-01

    In this paper we present an example of the application of molecular alloys for thermal protection of biomedical products during transport or storage. Particularly, thermal protection of blood elements have been considered at different temperatures. All steps from basic research to marketing have been addressed. The high latent heat of fusion of the components allows us to propose molecular alloys as materials for thermal energy storage and also for thermal protection over a large range of temperatures, which can be used in many industrial sectors.

  18. Thermal Exposure Effects on Properties of Al-Li Alloy Plate Products

    NASA Technical Reports Server (NTRS)

    Shah, Sandeep; Wells, Douglas; Wagner, John; Babel, Henry

    2002-01-01

    Aluminum-Lithium (AL-Li) alloys offer significant performance benefits for aerospace structural applications due to their higher specific properties compared with conventional aluminum alloys. For example, the application of an Al-Li alloy to the space shuttle external cryogenic fuel tank contributed to the weight savings that enabled successful deployment of International Space Station components. The composition and heat treatment of this alloy were optimized specifically for strength-toughness considerations for an expendable cryogenic tank. Time dependent properties related to reliability, such as thermal stability, fatigue, and corrosion, will be of significant interest when materials are evaluated for a reusable cryotank structure. As most aerospace structural hardware is weight sensitive, a reusable cryotank will be designed to the limits of the materials mechanical properties. Therefore, this effort was designed to establish the effects of thermal exposure on the mechanical properties and microstructure of one relatively production mature alloy and two developmental alloys C458 and L277. Tensile and fracture toughness behavior was evaluated after exposure to temperatures as high as 3oooF for up to IO00 hrs. Microstructural changes were also evaluated to correlate with the observed data trends. The ambient temperature parent metal data showed an increase in strength and reduction in elongation after exposure at lower temperatures. Strength reached a peak with intermediate temperature exposure followed by a decrease at highest exposure temperature. Characterizing the effect of thermal exposure on the properties of Al-Li alloys is important to defining a service limiting temperature, exposure time, and end-of-life properties.

  19. Thermal Exposure Effects on Properties of Al-Li Alloy Plate Products

    NASA Technical Reports Server (NTRS)

    Shah, Sandeep; Wells, Douglas; Wagner, John; Babel, Henry

    2002-01-01

    Aluminum-Lithium (AL-Li) alloys offer significant performance benefits for aerospace structural applications due to their higher specific properties compared with conventional aluminum alloys. For example, the application of an Al-Li alloy to the space shuttle external cryogenic fuel tank contributed to the weight savings that enabled successful deployment of International Space Station components. The composition and heat treatment of this alloy were optimized specifically for strength-toughness considerations for an expendable cryogenic tank. Time dependent properties related to reliability, such as thermal stability, fatigue, and corrosion, will be of significant interest when materials are evaluated for a reusable cryotank structure. As most aerospace structural hardware is weight sensitive, a reusable cryotank will be designed to the limits of the materials mechanical properties. Therefore, this effort was designed to establish the effects of thermal exposure on the mechanical properties and microstructure of one relatively production mature alloy and two developmental alloys C458 and L277. Tensile and fracture toughness behavior was evaluated after exposure to temperatures as high as 3oooF for up to IO00 hrs. Microstructural changes were also evaluated to correlate with the observed data trends. The ambient temperature parent metal data showed an increase in strength and reduction in elongation after exposure at lower temperatures. Strength reached a peak with intermediate temperature exposure followed by a decrease at highest exposure temperature. Characterizing the effect of thermal exposure on the properties of Al-Li alloys is important to defining a service limiting temperature, exposure time, and end-of-life properties.

  20. Examination of Corrosion Products and the Alloy Surface After Crevice Corrosion of a Ni-Cr-Mo- Alloy

    SciTech Connect

    X. Shan; J.H. Payer

    2006-06-09

    The objective of this study is to investigate the composition of corrosion products and the metal surface within a crevice after localized corrosion. The analysis provides insight into the propagation, stifling and arrest processes for crevice corrosion and is part of a program to analyze the evolution of localized corrosion damage over long periods of time, i.e. 10,000 years and longer. The approach is to force the initiation of crevice corrosion by applying anodic polarization to a multiple crevice assembly (MCA). Results are reported here for alloy C-22, a Ni-Cr-Mo alloy, exposed to a high temperature, concentrated chloride solution. Controlled crevice corrosion tests were performed on C-22 under highly aggressive, accelerated condition, i.e. 4M NaCl, 100 C and anodic polarization to -0.15V-SCE. The crevice contacts were by either a polymer tape (PTFE) compressed by a ceramic former or by a polymer (PTFE) crevice former. Figure 1 shows the polarization current during a crevice corrosion test. After an incubation period, several initiation-stifle-arrest events were indicated. The low current at the end of the test indicated that the metal surface had repassivated.

  1. Production of Magnesium and Aluminum-Magnesium Alloys from Recycled Secondary Aluminum Scrap Melts

    NASA Astrophysics Data System (ADS)

    Gesing, Adam J.; Das, Subodh K.; Loutfy, Raouf O.

    2016-02-01

    An experimental proof of concept was demonstrated for a patent-pending and trademark-pending RE12™ process for extracting a desired amount of Mg from recycled scrap secondary Al melts. Mg was extracted by electrorefining, producing a Mg product suitable as a Mg alloying hardener additive to primary-grade Al alloys. This efficient electrorefining process operates at high current efficiency, high Mg recovery and low energy consumption. The Mg electrorefining product can meet all the impurity specifications with subsequent melt treatment for removing alkali contaminants. All technical results obtained in the RE12™ project indicate that the electrorefining process for extraction of Mg from Al melt is technically feasible. A techno-economic analysis indicates high potential profitability for applications in Al foundry alloys as well as beverage—can and automotive—sheet alloys. The combination of technical feasibility and potential market profitability completes a successful proof of concept. This economical, environmentally-friendly and chlorine-free RE12™ process could be disruptive and transformational for the Mg production industry by enabling the recycling of 30,000 tonnes of primary-quality Mg annually.

  2. The Effect of Hydrazine Decomposition Products on the Mechanical Properties of High-Temperature Alloys

    DTIC Science & Technology

    1978-03-15

    3400- AFML-TR-77-95 THE EFFECT OF HYDRAZINE DECOMPOSITION _ PRODUCTS ON THE MECHANICAL PROPERTIES OF HIGH -TEMPERATURE ALLOYS ROCKETD YNE DIVISION...NOL.M GEER ’ Project Engineer High Temperature Mazerials Group FOR THE COKMANDER NORMAN M. TALLAN Chief, Processing and High Temperature Materials...THIS PAGE (Whuen Daee Fnte-rd) The Effect of Hydrazine Decomposition Products on Final (3. March 1976 to the Mechanical Properties of High -Temperature 1

  3. High-Efficiency Amorphous Silicon Alloy Based Solar Cells and Modules; Final Technical Progress Report, 30 May 2002--31 May 2005

    SciTech Connect

    Guha, S.; Yang, J.

    2005-10-01

    The principal objective of this R&D program is to expand, enhance, and accelerate knowledge and capabilities for development of high-efficiency hydrogenated amorphous silicon (a-Si:H) and amorphous silicon-germanium alloy (a-SiGe:H) related thin-film multijunction solar cells and modules with low manufacturing cost and high reliability. Our strategy has been to use the spectrum-splitting triple-junction structure, a-Si:H/a-SiGe:H/a-SiGe:H, to improve solar cell and module efficiency, stability, and throughput of production. The methodology used to achieve the objectives included: (1) explore the highest stable efficiency using the triple-junction structure deposited using RF glow discharge at a low rate, (2) fabricate the devices at a high deposition rate for high throughput and low cost, and (3) develop an optimized recipe using the R&D batch large-area reactor to help the design and optimization of the roll-to-roll production machines. For short-term goals, we have worked on the improvement of a-Si:H and a-SiGe:H alloy solar cells. a-Si:H and a-SiGe:H are the foundation of current a-Si:H based thin-film photovoltaic technology. Any improvement in cell efficiency, throughput, and cost reduction will immediately improve operation efficiency of our manufacturing plant, allowing us to further expand our production capacity.

  4. Welding of NOREM iron-base hardfacing alloy wire products: Procedures for gas tungsten arc welding. Interim report

    SciTech Connect

    Phillps, M.K.; Findlan, S.J.

    1992-09-01

    New wire products have been successfully fabricated and procedures developed for automatic gas tungsten arc welding of wear-resistant NOREM iron-base alloys. Research demonstrated that sound multilayer welds on carbon and stainless steel substrates can be obtained without the use of preheating. These developments point to the advantages of NOREM alloys for field applications, such as valve refurbishing.

  5. The production of fine grained magnesium alloys through thermomechanical processing for the optimization of microstructural and mechanical properties

    NASA Astrophysics Data System (ADS)

    Young, John Paul

    The low density and high strength to weight ratio of magnesium alloys makes them ideal candidates to replace many of the heavier steel and aluminum alloys currently used in the automotive and other industries. Although cast magnesium alloys components have a long history of use in the automotive industry, the integration of wrought magnesium alloys components has been hindered by a number of factors. Grain refinement through thermomechanical processing offers a possible solution to many of the inherent problems associated with magnesium alloys. This work explores the development of several thermomechanical processing techniques and investigates their impact on the microstructural and mechanical properties of magnesium alloys. In addition to traditional thermomechanical processing, this work includes the development of new severe plastic deformation techniques for the production of fine grain magnesium plate and pipe and develops a procedure by which the thermal microstructural stability of severely plastically deformed microstructures can be assessed.

  6. Effect of product form upon fatigue-crack growth behavior in Alloy 718: additional results

    SciTech Connect

    James, L A

    1980-08-01

    A previous study had characterized the fatigue-crack growth behavior of four wrought product forms (sheet, plate, bar and forging) from a single heat of Alloy 718 and concluded that there were no consistent trends in the crack growth rate results that could be attributed to product form variability. The present study adds one additional product form (gas-tungsten-arc weldments) from the same heat, and compares the behavior to that exhibited by the wrought product forms. Two different precipitation heat-treatments were employed at each of five test temperatures (24, 316, 427, 538, and 649{sup 0}C).

  7. The effect of product form upon fatigue-crack growth behavior in Alloy 718: Additional results

    SciTech Connect

    James, L.A.

    1980-08-01

    A previous study had characterized the fatigue-crack growth behavior of four wrought product forms (sheet, plate, bar and forging) from a single heat of Alloy 718 and concluded that there were no consistent trends in the crack growth rate results that could be attributed to product form variability. The present study adds one additional product form (gas-tungsten-arc weldments) from the same heat, and compares the behavior to that exhibited by the wrought product forms. Two different precipitation heat-treatments were employed at each of five test temperatures. 11 refs., 5 figs., 3 tabs.

  8. Feasibility study of the production of biomedical Ti-6Al-4V alloy by powder metallurgy.

    PubMed

    Bolzoni, L; Ruiz-Navas, E M; Gordo, E

    2015-04-01

    Titanium and its alloys are characterized by an exceptional combination of properties like high strength, good corrosion resistance and biocompatibility which makes them suitable materials for biomedical prosthesis and devices. The wrought Ti-6Al-4V alloy is generally favored in comparison to other metallic biomaterials due to its relatively low elastic modulus and it has been long used to obtain products for biomedical applications. In this work an alternative route to fabricate biomedical implants made out of the Ti-6Al-4V alloy is investigated. Specifically, the feasibility of the conventional powder metallurgy route of cold uniaxial pressing and sintering is addressed by considering two types of powders (i.e. blended elemental and prealloyed). The characterization of physical properties, chemical analysis, mechanical behavior and microstructural analysis is carried out in-depth and the properties are correlated among them. On the base of the results found, the produced alloys are promising materials for biomedical applications as well as cheaper surgical devices and tools.

  9. The consequences of helium production on microstructural development in isotopically tailored ferritic alloys

    SciTech Connect

    Gelles, D.S.

    1996-10-01

    A series of alloys have been made adding various isotopes of nickel in order to vary the production of helium during irradiation by a two step nuclear reaction in a mixed spectrum reactor. The alloys use a base composition of Fe-12Cr with an addition of 1.5% nickel, either in the form of {sup 60}Ni which produces no helium, {sup 59}Ni which produces helium at a rate of about 10 appm He/dpa, or natural nickel ({sup Nat}Ni) which provides an intermediate level of helium due to delayed development of {sup 59}Ni. Specimens were irradiated in the HFIR at Oak Ridge, TN to {approx}7 dpa at 300 and 400{degrees}C. Microstructural examinations indicated that nickel additions promote precipitation in all alloys, but the effect appears to be much stronger at 400{degrees}C than at 300{degrees}C. There is sufficient dose by 7 dpa (and with 2 appm He) to initiate void swelling in ferritic/martensitic alloys. Little difference was found between response from {sup 59}Ni and {sup Nat}Ni. Also, helium bubble development for high helium generation conditions appeared to be very different at 300 and 400{degrees}C. At 300{degrees}C, it appeared that high densities of bubbles formed whereas at 400{degrees}C, bubbles could not be identified, possibly because of the complexity of the microstructure, but more likely because helium accumulated at precipitate interfaces.

  10. Production Process of Biocompatible Magnesium Alloy Tubes Using Extrusion and Dieless Drawing Processes

    NASA Astrophysics Data System (ADS)

    Kustra, Piotr; Milenin, Andrij; Płonka, Bartłomiej; Furushima, Tsuyoshi

    2016-06-01

    Development of technological production process of biocompatible magnesium tubes for medical applications is the subject of the present paper. The technology consists of two stages—extrusion and dieless drawing process, respectively. Mg alloys for medical applications such as MgCa0.8 are characterized by low technological plasticity during deformation that is why optimization of production parameters is necessary to obtain good quality product. Thus, authors developed yield stress and ductility model for the investigated Mg alloy and then used the numerical simulations to evaluate proper manufacturing conditions. Grid Extrusion3d software developed by authors was used to determine optimum process parameters for extrusion—billet temperature 400 °C and extrusion velocity 1 mm/s. Based on those parameters the tube with external diameter 5 mm without defects was manufactured. Then, commercial Abaqus software was used for modeling dieless drawing. It was shown that the reduction in the area of 60% can be realized for MgCa0.8 magnesium alloy. Tubes with the final diameter of 3 mm were selected as a case study, to present capabilities of proposed processes.

  11. Cathodic H2 gas production through Pd alloy membrane electrodes

    NASA Astrophysics Data System (ADS)

    Shirogami, T.; Murata, K.

    A rechargeable H2-NiOOH cell with hydrogen-permeable membrane electrode was tested, and its cathodic hydrogen gas production through the membrane electrode investigated. When a Pd-Pt, catalyzed electrolyte-facing surface was cathodically polarized in a concentrated KOH solution, it was found that hydrogen gas was evolved in the chamber through dissolved hydrogen atoms' penetrating of the membrane to exit at the other, palladized surface as free gas.

  12. Review of the Methods for Production of Spherical Ti and Ti Alloy Powder

    NASA Astrophysics Data System (ADS)

    Sun, Pei; Fang, Zhigang Zak; Zhang, Ying; Xia, Yang

    2017-10-01

    Spherical titanium alloy powder is an important raw material for near-net-shape fabrication via a powder metallurgy (PM) manufacturing route, as well as feedstock for powder injection molding, and additive manufacturing (AM). Nevertheless, the cost of Ti powder including spherical Ti alloy has been a major hurdle that prevented PM Ti from being adopted for a wide range of applications. Especially with the increasing importance of powder-bed based AM technologies, the demand for spherical Ti powder has brought renewed attention on properties and cost, as well as on powder-producing processes. The performance of Ti components manufactured from powder has a strong dependence on the quality of powder, and it is therefore crucial to understand the properties and production methods of powder. This article aims to provide a cursory review of the basic techniques of commercial and emerging methods for making spherical Ti powder. The advantages as well as limitations of different methods are discussed.

  13. Review of the Methods for Production of Spherical Ti and Ti Alloy Powder

    NASA Astrophysics Data System (ADS)

    Sun, Pei; Fang, Zhigang Zak; Zhang, Ying; Xia, Yang

    2017-08-01

    Spherical titanium alloy powder is an important raw material for near-net-shape fabrication via a powder metallurgy (PM) manufacturing route, as well as feedstock for powder injection molding, and additive manufacturing (AM). Nevertheless, the cost of Ti powder including spherical Ti alloy has been a major hurdle that prevented PM Ti from being adopted for a wide range of applications. Especially with the increasing importance of powder-bed based AM technologies, the demand for spherical Ti powder has brought renewed attention on properties and cost, as well as on powder-producing processes. The performance of Ti components manufactured from powder has a strong dependence on the quality of powder, and it is therefore crucial to understand the properties and production methods of powder. This article aims to provide a cursory review of the basic techniques of commercial and emerging methods for making spherical Ti powder. The advantages as well as limitations of different methods are discussed.

  14. The huastec region: a second locus for the production of bronze alloys in ancient mesoamerica.

    PubMed

    Hosler, D; Stresser-Pean, G

    1992-08-28

    Chemical analyses of 51 metal artifacts, one ingot, and two pieces of intermediate processed material from two Late Post Classic archeological sites in the Huastec area of Eastern Mesoamerica point to a second production locus for copper-arsenic-tin alloys, copper-arsenic-tin artifacts, and probably copper-tin and copper-arsenic bronze artifacts. Earlier evidence had indicated that these bronze alloys were produced exclusively in West Mexico. West Mexico was the region where metallurgy first developed in Mesoamerica, although major elements of that technology had been introduced from the metallurgies of Central and South America. The bronze working component of Huastec metallurgy was transmitted from the metalworking regions of West Mexico, most likely through market systems that distributed Aztec goods.

  15. IMPROVED PRODUCTION OF POWDER METALLURGY ITEMS.

    DTIC Science & Technology

    POWDER METALLURGY, *POWDER ALLOYS , MATERIAL FORMING, PRODUCTION, NICKEL ALLOYS , CHROMIUM ALLOYS , COBALT ALLOYS , SINTERING, FORGING, PARTICLE SIZE...HIGH TEMPERATURE, SCIENTIFIC RESEARCH, HOT WORKING, HEAT TREATMENT, MICROSTRUCTURE, HARDNESS, MOLYBDENUM ALLOYS , TITANIUM ALLOYS , ZIRCONIUM ALLOYS , CARBON ALLOYS .

  16. Degradation of bioabsorbable Mg-based alloys: Assessment of the effects of insoluble corrosion products and joint effects of alloying components on mammalian cells.

    PubMed

    Grillo, Claudia A; Alvarez, Florencia; Fernández Lorenzo de Mele, Mónica A

    2016-01-01

    This work is focused on the processes occurring at the bioabsorbable metallic biomaterial/cell interfaces that may lead to toxicity. A critical analysis of the results obtained when degradable metal disks (pure Mg and rare earth-containing alloys (ZEK100 alloys)) are in direct contact with cell culture and those obtained with indirect methods such as the use of metal salts and extracts was made. Viability was assessed by Acridine Orange dye, neutral red and clonogenic assays. The effects of concentration of corrosion products and possible joint effects of the binary and ternary combinations of La, Zn and Mg ions, as constituents of ZEK alloys, were evaluated on a mammalian cell culture. In all cases more detrimental effects were found for pure Mg than for the alloys. Experiments with disks showed that gradual alterations in pH and in the amount of corrosion products were better tolerated by cells and resulted in higher viability than abrupt changes. In addition, viability was dependent on the distance from the source of ions. Experiments with extracts showed that the effect of insoluble degradation products was highly detrimental. Indirect tests with Zn ions revealed that harmful effects may be found at concentrations ≥ 150 μM and at ≥ 100 μM in mixtures with Mg. These mixtures lead to more deleterious effects than single ions. Results highlight the need to develop a battery of tests to evaluate the biocompatibility of bioabsorbable biomaterials.

  17. Mg-Ca Alloys Produced by Reduction of CaO: Understanding of ECO-Mg Alloy Production

    NASA Astrophysics Data System (ADS)

    Jung, In-Ho; Lee, Jin Kyu; Kim, Shae K.

    2017-04-01

    There have been long debates about the environment conscious (ECO) Mg technology which utilizes CaO to produce Ca-containing Mg alloys. Two key process technologies of the ECO-Mg process are the chemical reduction of CaO by liquid Mg and the maintenance of melt cleanliness during the alloying of Ca. Thermodynamic calculations using FactSage software were performed to explain these two key issues. In addition, an experimental study was performed to compare the melt cleanliness of the Ca-containing Mg alloys produced by the conventional route with metallic Ca and the ECO-Mg route with CaO.

  18. Mg-Ca Alloys Produced by Reduction of CaO: Understanding of ECO-Mg Alloy Production

    NASA Astrophysics Data System (ADS)

    Jung, In-Ho; Lee, Jin Kyu; Kim, Shae K.

    2016-12-01

    There have been long debates about the environment conscious (ECO) Mg technology which utilizes CaO to produce Ca-containing Mg alloys. Two key process technologies of the ECO-Mg process are the chemical reduction of CaO by liquid Mg and the maintenance of melt cleanliness during the alloying of Ca. Thermodynamic calculations using FactSage software were performed to explain these two key issues. In addition, an experimental study was performed to compare the melt cleanliness of the Ca-containing Mg alloys produced by the conventional route with metallic Ca and the ECO-Mg route with CaO.

  19. Production of Al-Co-Ni Ternary Alloys by the SHS Method for Use in Nickel Based Superalloys Manufacturing

    NASA Astrophysics Data System (ADS)

    Alkan, Murat; Sonmez, M. Seref; Derin, Bora; Yücel, Onuralp; Andreev, Dmitrii E.; Sanin, Vladimir N.; Yukhvid, Vladimir I.

    2015-05-01

    In this study, Al-Co-Ni ternary alloys were synthesized, in order to obtain low-cost starting material for Ni-based superalloy production, by a self-propagating high temperature synthesis (SHS) both under normal gravity conditions (a = 9.81 m/s2) and under high gravity conditions (up to 1000 g-force) by using a centrifugal machine. The mixture of Co3O4-NiO powder were reduced by Al powder for the production of SHS alloys with the estimated compositions of 5-10 mass% Al, 20-65 mass% Co, 25-75 mass% Ni. The effect of green mixture compositions and centrifugal overload on combustion temperature, alloy/slag separations, chemical composition and microstructure of final alloys were investigated. The chemical analysis results showed that production of SHS alloys were achieved by having up to 86.12% of Co and 92.32% of Ni recoveries. The highest metal recovery value was obtained in SHS alloy with the estimated composition of 10%Al-65%Co-25%Ni by the addition of 20% Al2O3 into the green mixture. The metal/slag separation efficiency increased by increasing the centrifugal overload.

  20. Production of Fe from Fe2O3 using a dry Mechanical Alloying Process

    SciTech Connect

    Waanders, F.B.; Mulaba-Bafubiandi, A.F.

    2005-04-26

    Mechanical alloying has been, and is still being employed extensively to synthesize a variety of alloy phases. The primary interest is to produce materials for scientific research and technological applications for magnetic recording media and permanent magnetic field devices. In the present investigation however the aim was not to produce a special alloy phases but to prove the viability of the production of iron from naturally occurring hematite, using mechanical alloying. Discard fines from the biggest hematite producer, Kumba Resources, Sishen, South Africa, were obtained and mixed with aluminum powder in the ratio of 25 at.% Al, balance hematite. About 50 g of the hematite-Al mixture, to be mechanically milled, was dry milled in a planetary ball milling equipment. The milling times varied between 30 min. and 30 hours and samples for Moessbauer spectroscopy, SEM analyses and Malvern sizing were obtained for each milling interval. Milling of the fine hematite with the much coarser Al resulted in a mixture with a particle size distribution of d0.5 = 54{mu}m to be extracted from the mill after 30 min. The Moessbauer spectra yielded 93% Fe2O3 and a 7% intermetallic Fe-Al component for this milling period. A final particle size of d0.5 = 20{mu}m for the milled product was obtained after milling for up to 30 h. However, within an hour all the hematite was completely converted to iron ({approx_equal} 86%) and two intermetallic Fe-Al compounds of combined intensity {approx_equal} 14%. The intensity ratio of the two intermetallic Fe-Al alloys that were observed as two doublets, changed after 3 h milling time and the averaged Moessbauer parameters for the two doublets are reported as: D1 = ({delta} = 0.50 {+-} 0.03 mm.s-1 and {delta} = 0.24 {+-} 0.03 mm.s-1) and D2 = ({delta} = 2.07 {+-} 0.03 mm.s-1 and {delta} = 0.98 {+-} 0.03 mm.s-1) respectively.

  1. Production of Dense Compact Billet From Ti-Alloy Powder Using Equal Channel Angular Extrusion

    DTIC Science & Technology

    2007-04-06

    dry lubricant 2 175 RT 95.3 dry lubricant 3 262 RT 95.6 dry lubricant 4 21 100 95.4 dry lubricant 5 43 100 96 dry lubricant 6 175 100 96.2 dry...175 98.1 371 3 262 98.2 426 4 350 98.3 412 ECAE compaction with Al tubes 5 350 97.4 415 6 393 97.8 419 7 436 97.6 438 8* 480 98.6 431 ECAE...PRODUCTION OF DENSE COMPACT BILLET FROM Ti-ALLOY POWDER USING EQUAL CHANNEL ANGULAR EXTRUSION Final Report 4 /06/2007

  2. In-situ monitoring of surface hydrogen on the a-SiGe:H films

    SciTech Connect

    Toyoshima, Y.; Ganguly, G.; Ikeda, T.; Saitoh, K.; Kondo, M.; Matsuda, A.

    1997-07-01

    The bonded hydrogen on the growing surface of hydrogenated amorphous silicon germanium (a-SiGe:H) alloy films has been investigated by use of infrared reflection absorption spectroscopy (IR-RAS). When the alloy films are Si-rich, the surface hydrogen bonded to Si atoms is found to behave in a similar way to those on the hydrogenated amorphous silicon (a-Si:H) films. This means that the thermal desorption stability of surface Si hydride species is not significantly affected by the coexistence of a small amount (typically 20 at.%) of Ge. On the contrary, the desorption behavior of surface hydrogen depends on the alloy composition when the a-SiGe:H films are Ge-rich. A surface reaction scheme is provided in an attempt to explain this series of behavior in surface hydrogen on the a-SiGe:H films.

  3. Effect of the surface state of the Ti-Ni alloy products on the shape memory effect parameters

    NASA Astrophysics Data System (ADS)

    Prokoshkin, S. D.; Ryklina, E. P.; Chernavina, A. A.; Abramov, V. Ya.; Krestnikov, N. S.

    2009-12-01

    The depth profiles of the structure, composition, and properties of the oxide layer that forms on the surface of Ti-Ni alloy products during postdeformation annealing (PDA) are studied. These parameters depend substantially on the holding temperature and time during PDA. The application of low-temperature thermomechanical treatment improves the state of surface as compared to quenching due to a decrease in the oxide-layer depth by more than an order of magnitude. The state of the surface of Ti-Ni alloy products significantly affects the characteristic martensite transformation temperatures and the shape memory effect parameters. This effect is more pronounced as the sample thickness (diameter) decreases. It is impossible to predict this effect on the entire set of the functional properties of the alloy products because of its ambiguity. Therefore, the oxide layer should be removed by etching to obtain reliable and reproducible results.

  4. Scale up of NiTi shape memory alloy production by EBM

    NASA Astrophysics Data System (ADS)

    Otubo, J.; Rigo, O. D.; Moura Neto, C.; Kaufman, M. J.; Mei, P. R.

    2003-10-01

    The usual process to produce NiTi shape memory alloy is by vacuum induction melting (VIM) using a graphite crucible, which causes contamination of the melt with carbon. Contamination with oxygen originates from the residual oxygen inside the melting chamber. An alternative process to produce NiTi alloys is by electron beam melting (EBM) using a water-cooled copper crucible that eliminates carbon contamination, and the oxygen contamination would be minimal due to operation in a vacuum of better than 10^{-2} Pa. In a previous work, it was demonstrated that the technique is feasible for button shaped samples weighing around 30g. The present work presents the results on the scale up program that enables the production of larger samples/ingots. The results are very promising in terms of chemical composition homogeneity as well as in terms of carbon contamination, the latter being four to ten times lower than the commercially-produced VIM products, and in terms of final oxygen content which is shown to depend primarily on the starting raw materials.

  5. Molecular dynamics simulations of high energy cascade in ordered alloys: Defect production and subcascade division

    NASA Astrophysics Data System (ADS)

    Crocombette, Jean-Paul; Van Brutzel, Laurent; Simeone, David; Luneville, Laurence

    2016-06-01

    Displacement cascades have been calculated in two ordered alloys (Ni3Al and UO2) in the molecular dynamics framework using the CMDC (Cell Molecular Dynamics for Cascade) code (J.-P. Crocombette and T. Jourdan, Nucl. Instrum. Meth. B 352, 9 (2015)) for energies ranking between 0.1 and 580 keV. The defect production has been compared to the prediction of the NRT (Norgett, Robinson and Torrens) standard. One observes a decrease with energy of the number of defects compared to the NRT prediction at intermediate energies but, unlike what is commonly observed in elemental solids, the number of produced defects does not always turn to a linear variation with ballistic energy at high energies. The fragmentation of the cascade into subcascades has been studied through the analysis of surviving defect pockets. It appears that the common knowledge equivalence of linearity of defect production and subcascades division does not hold in general for alloys. We calculate the average number of subcascades and average number of defects per subcascades as a function of ballistic energy. We find an unexpected variety of behaviors for these two average quantities above the threshold for subcascade formation.

  6. Continuous roll-to-roll serpentine deposition for high throughput a-Si PV manufacturing

    SciTech Connect

    Izu, M.; Ovshinsky, H.C.; Deng, X.; Krisko, A.J.; Narasimhan, K.L.; Crucet, R.; Laarman, T.; Myatt, A.; Ovshinsky, S.R.

    1994-12-31

    In order to further improve the economies of scale which are inherent in ECD`s continuous roll-to-roll amorphous silicon alloy solar cell manufacturing process, the authors have developed a concept for a serpentine web plasma CVD deposition process to maximize throughput while keeping the size of the deposition chambers small. When this technique is incorporated into a continuous roll-to-roll PV manufacturing process, it will maximize the throughput for a high volume production plant, reduce the machine cost, improve gas utilization, reduce power consumption, and improve the solar cell stability. To demonstrate the serpentine web deposition concept, the authors have constructed a single loop serpentine deposition chamber to deposit a-Si for n-i-p structure solar cells. During the initial process of optimization, they have produced single-junction a-Si solar cells with 8.6% efficiency, and triple-junction a-Si solar cells with a 9.5% initial efficiency, where the top cell intrinsic layer was deposited in the serpentine deposition chamber.

  7. Production of High-Purity Anhydrous Nickel(II) Perrhenate for Tungsten-Based Sintered Heavy Alloys.

    PubMed

    Leszczyńska-Sejda, Katarzyna; Benke, Grzegorz; Kopyto, Dorota; Majewski, Tomasz; Drzazga, Michał

    2017-04-24

    This paper presents a method for the production of high-purity anhydrous nickel(II) perrhenate. The method comprises sorption of nickel(II) ions from aqueous nickel(II) nitrate solutions, using strongly acidic C160 cation exchange resin, and subsequent elution of sorbed nickel(II) ions using concentrated perrhenic acid solutions. After the neutralization of the resulting rhenium-nickel solutions, hydrated nickel(II) perrhenate is then separated and then dried at 160 °C to obtain the anhydrous form. The resulting compound is reduced in an atmosphere of dissociated ammonia in order to produce a Re-Ni alloy powder. This study provides information on the selected properties of the resulting Re-Ni powder. This powder was used as a starting material for the production of 77W-20Re-3Ni heavy alloys. Microstructure examination results and selected properties of the produced sintered heavy alloys were compared to sintered alloys produced using elemental W, Re, and Ni powders. This study showed that the application of anhydrous nickel(II) perrhenate in the production of 77W-20Re-3Ni results in better properties of the sintered alloys compared to those made from elemental powders.

  8. Production of High-Purity Anhydrous Nickel(II) Perrhenate for Tungsten-Based Sintered Heavy Alloys

    PubMed Central

    Leszczyńska-Sejda, Katarzyna; Benke, Grzegorz; Kopyto, Dorota; Majewski, Tomasz; Drzazga, Michał

    2017-01-01

    This paper presents a method for the production of high-purity anhydrous nickel(II) perrhenate. The method comprises sorption of nickel(II) ions from aqueous nickel(II) nitrate solutions, using strongly acidic C160 cation exchange resin, and subsequent elution of sorbed nickel(II) ions using concentrated perrhenic acid solutions. After the neutralization of the resulting rhenium-nickel solutions, hydrated nickel(II) perrhenate is then separated and then dried at 160 °C to obtain the anhydrous form. The resulting compound is reduced in an atmosphere of dissociated ammonia in order to produce a Re-Ni alloy powder. This study provides information on the selected properties of the resulting Re-Ni powder. This powder was used as a starting material for the production of 77W-20Re-3Ni heavy alloys. Microstructure examination results and selected properties of the produced sintered heavy alloys were compared to sintered alloys produced using elemental W, Re, and Ni powders. This study showed that the application of anhydrous nickel(II) perrhenate in the production of 77W-20Re-3Ni results in better properties of the sintered alloys compared to those made from elemental powders. PMID:28772808

  9. Fundamental studies on electrochemical production of dendrite-free aluminum and titanium-aluminum alloys

    NASA Astrophysics Data System (ADS)

    Pradhan, Debabrata

    A novel dendrite-free electrorefining of aluminum scrap was investigated by using AlCl3-1-Ethyl-3-methyl-imidazolium chloride (EMIC) ionic liquid electrolyte. Electrodeposition of aluminum were conducted on copper/aluminum cathodes at voltage of 1.5 V, temperatures (50-110°C), stirring rate (0-120 rpm), molar ratio (MR) of AlCl3:EMIC (1.25-2.0) and electrode surface modification (modified/unmodified). The study was focused to investigate the effect of process variables on deposit morphology, cathode current density and their role in production of dendrite-free aluminum. The deposits were characterized using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Modified electrodes and stirring rate (60 rpm) eliminate dendritic deposition by reducing cathode overpotential below critical overpotential (etacrt≈ -0.54 V) for dendrite formation. Pure aluminum (>99%) was deposited with current efficiency of 84-99%. Chronoamperometry study was conducted using AlCl3-EMIC and AlCl3-1-Butyl-3-methyl-imidazolium chloride (BMIC) (MR = 1.65:1) at 90°C to understand the mechanism of aluminum electrodeposition and find out diffusion parameter of electroactive species Al2C 7-. It was concluded that electrodeposition of aluminum is a diffusion controlled instantaneous nucleation process and diffusion coefficient of Al2C7- was found to be 5.2-6.9 x 10-11 m2/s and 2.2 x 10-11 m2/s for AlCl3-EMIC and AlCl3-BMIC, respectively. A novel production route of Ti-Al alloys was investigated using AlCl 3-BMIC-TiCl4 (MR = 2:1:0.019) and AlCl3-BMIC (MR = 2:1) electrolytes at constant voltages of 1.5-3.0 V and temperatures (70-125°C). Ti sheet was used as anode and cathode. Characterization of electrodeposited Ti-Al alloys was carried out using SEM, EDS, XRD and inductively coupled plasma-optical emission spectrometer (ICP-OES). Effect of voltage and temperature on cathode current density, current efficiency, composition and morphology of Ti

  10. MECHANICAL ALLOYING AND THERMAL TREATMENT FOR PRODUCTION OF ZIRCONIUM IRON HYDROGEN ISOTOPE GETTERS

    SciTech Connect

    Fox, K.

    2008-02-20

    The objective of this task was to demonstrate that metal hydrides could be produced by mechanical alloying in the quantities needed to support production-scale hydrogen isotope separations. Three starting compositions (ratios of elemental Zr and Fe powders) were selected and attritor milled under argon for times of 8 to 60 hours. In general, milling times of at least 24 hours were required to form the desired Zr{sub 2}Fe and Zr{sub 3}Fe phases, although a considerable amount of unalloyed Zr and Fe remained. Milling in liquid nitrogen does not appear to provide any advantages over milling in hexane, particularly due to the formation of ZrN after longer milling times. Carbides of Zr formed during some of the milling experiments in hexane. Elemental Zr was present in the as-milled material but not detected after annealing for milling times of 48 and 60 hours. It may be that after intimate mixing of the powders in the attritor mill the annealing temperature was sufficient to allow for the formation of a Zr-Fe alloy. Further investigation of this conversion is necessary, and could provide an opportunity for reducing the amount of unreacted metal powder after milling.

  11. Evaluation of particulate matter emissions from manganese alloy production using life-cycle assessment.

    PubMed

    Davourie, Julia; Westfall, Luke; Ali, Mohammed; McGough, Doreen

    2017-01-01

    Life-cycle assessments (LCAs) provide a wealth of industry data to assist in evaluating the environmental impacts of industrial processes and product supply chains. In this investigation, data from a recent LCA covering global manganese alloy production was used to evaluate sources of particulate matter (PM) emissions associated with the manganese alloy supply chain. The analysis is aimed at providing an empirical, industry-averaged breakdown of the contribution that processes and emissions controls have on total emissions, manganese releases and occupational exposure. The assessment shows that 66% of PM emissions associated with manganese production occur beyond manganese facilities. Direct or on-site emissions represent 34% of total PM and occur predominantly as disperse sources during mineral extraction and hauling, and as primary furnace emissions. The largest contribution of manganese-bearing PM at ground-level is associated with fugitive emissions from metal and slag tapping, casting, crushing and screening. The evaluation provides a high-level ranking of emissions by process area, to assist in identifying priority areas for industry-wide initiatives to reduce emissions and occupational exposure of manganese. The range of PM emission levels in industry indicate that further enhancements in PM emissions can be achieved by sharing of best practices in emissions controls, limiting furnace conditions which lead to by-passing of emissions controls and application of secondary emission controls to capture fugitive emissions during tapping and casting. The LCA approach to evaluating PM emissions underscores the important role that process optimization and resource efficiency have on reducing PM emissions throughout the manganese supply chain.

  12. Electrochemical study on the adsorption of carbon oxides and oxidation of their adsorption products on platinum group metals and alloys.

    PubMed

    Siwek, Hanna; Lukaszewski, Mariusz; Czerwiński, Andrzej

    2008-07-07

    CO(2) reduction and CO adsorption on noble metals (Pt, Rh, Pd) and their alloys (Pt-Rh, Pd-Pt, Pd-Rh, Pd-Pt-Rh) prepared as thin rough deposits have been studied by chronoamperometry (CA), cyclic voltammetry (CV) and the electrochemical quartz crystal microbalance (EQCM). The influence of alloy surface composition on the values of surface coverage, eps (electron per site) and potential of the oxidation of CO(2) reduction and CO adsorption products is shown. The oxidation of the adsorbate on Pt-Rh alloys proceeds more easily (at lower potentials) than on pure metals. On the other hand, in the case of Pd-Pt and Pd-Rh alloys the adsorbate oxidation is more difficult and requires higher potentials than on Pt or Rh. The analysis of the EQCM signal is presented for the case of adsorption and oxidation of carbon oxide adsorption products on the electrodes studied. The comparison of adsorption parameters and the EQCM response obtained for platinum group metals and alloys leads to the conclusion that reduced CO(2) cannot be totally identified with adsorbed CO.

  13. Development of Low Cost Gas Atomization of Precursor Powders for Simplified ODS Alloy Production

    SciTech Connect

    Anderson, Iver

    2014-08-05

    A novel gas atomization reaction synthesis (GARS) method was developed in this project to enable production (at our partner’s facility) a precursor Ni-Cr-Y-Ti powder with a surface oxide and an internal rare earth (RE) containing intermetallic compound (IMC) phase. Consolidation and heat-treatment experiments were performed at Ames Lab to promote the exchange of oxygen from the surface oxide to the RE intermetallic to form nano-metric oxide dispersoids. Alloy selection was aided by an internal oxidation and serial grinding experiments at Ames Lab and found that Hf-containing alloys may form more stable dispersoids than Ti-containing alloy, i.e., the Hf-containing system exhibited five different oxide phases and two different intermetallics compared to the two oxide phases and one intermetallic in the Ti-containing alloys. Since the simpler Ti-containing system was less complex to characterize, and make observations on the effects of processing parameters, the Ti-containing system was selected by Ames Lab for experimental atomization trials at our partner. An internal oxidation model was developed at Ames Lab and used to predict the heat treatment times necessary for dispersoid formation as a function of powder size and temperature. A new high-pressure gas atomization (HPGA) nozzle was developed at Ames Lab with the aim of promoting fine powder production at scales similar to that of the high gas-flow and melt-flow of industrial atomizers. The atomization nozzle was characterized using schlieren imaging and aspiration pressure testing at Ames Lab to determine the optimum melt delivery tip geometry and atomization pressure to promote enhanced secondary atomization mechanisms. Six atomization trials were performed at our partner to investigate the effects of: gas atomization pressure and reactive gas concentration on the particle size distribution (PSD) and the oxygen content of the resulting powder. Also, the effect on the rapidly solidified microstructure (as a

  14. Advancements in Ti Alloy Powder Production by Close-Coupled Gas Atomization

    SciTech Connect

    Heidloff, Andy; Rieken, Joel; Anderson, Iver; Byrd, David

    2011-04-01

    As the technology for titanium metal injection molding (Ti-MIM) becomes more readily available, efficient Ti alloy fine powder production methods are required. An update on a novel close-coupled gas atomization system has been given. Unique features of the melting apparatus are shown to have measurable effects on the efficiency and ability to fully melt within the induction skull melting system (ISM). The means to initiate the melt flow were also found to be dependent on melt apparatus. Starting oxygen contents of atomization feedstock are suggested based on oxygen pick up during the atomization and MIM processes and compared to a new ASTM specification. Forming of titanium by metal injection molding (Ti-MIM) has been extensively studied with regards to binders, particle shape, and size distribution and suitable de-binding methods have been discovered. As a result, the visibility of Ti-MIM has steadily increased as reviews of technology, acceptability, and availability have been released. In addition, new ASTM specification ASTM F2885-11 for Ti-MIM for biomedical implants was released in early 2011. As the general acceptance of Ti-MIM as a viable fabrication route increases, demand for economical production of high quality Ti alloy powder for the preparation of Ti-MIM feedstock correspondingly increases. The production of spherical powders from the liquid state has required extensive pre-processing into different shapes thereby increasing costs. This has prompted examination of Ti-MIM with non-spherical particle shape. These particles are produced by the hydride/de-hydride process and are equi-axed but fragmented and angular which is less than ideal. Current prices for MIM quality titanium powder range from $40-$220/kg. While it is ideal for the MIM process to utilize spherical powders within the size range of 0.5-20 {mu}m, titanium's high affinity for oxygen to date has prohibited the use of this powder size range. In order to meet oxygen requirements the top size

  15. Fission Product Release from Molten U/Al Alloy Fuel: A Vapor Transpiration Model

    SciTech Connect

    Whitkop, P.G.

    2001-06-26

    This report describes the application of a vapor transportation model to fission product release data obtained for uranium/aluminum alloy fuel during early Oak Ridge fuel melt experiments. The Oak Ridge data validates the vapor transpiration model and suggests that iodine and cesium are released from the molten fuel surface in elemental form while tellurium and ruthenium are released as oxides. Cesium iodide is postulated to form in the vapor phase outside of the fuel matrix. Kinetic data indicates that cesium iodide can form from Cs atoms and diatomic iodine in the vapor phase. Temperatures lower than those capable of melting fuel are necessary in order to maintain a sufficient I2 concentration. At temperatures near the fuel melting point, cesium can react with iodine atoms to form CsI only on solid surfaces such as aerosols.

  16. Large-scale production of Si{sub 0.8}Ge{sub 0.2} thermoelectric alloys by mechanical alloying

    SciTech Connect

    Cook, B.A.; Harringa, J.L.; Loughin, S.; Centurioni, D.X.

    1993-10-01

    Advanced processing techniques were combined with refinements in composition to produce homogeneous, production-scale quantities of n- and p-type Si{sub 0.8}Ge{sub 0.2} alloys with improved thermoelectric properties. Two p-type compacts of Si{sub 0.8}Ge{sub 0.2} doped with 0.8 atom% boron and one n-type compact doped with 0.8 m/o GaP and a P/Ga ratio of 2.38 were prepared by mechanical alloying. Resulting powders were consolidated into 7.62 cm diameter compacts by vacuum hot pressing. Transport and thermoelectric properties were measured. As-pressed samples were found to have low carrier mobility. Metallographic analysis revealed a sub-micron grain size which would suggest a high density of grain boundary potential barriers. A heat treatment was applied and the measurements were repeated. The post-treatment p-type samples showed a 33% grain growth and an integrated average figure of merit of 0.6{times}10{sup {minus}3} K{sup {minus}1} over the 573--1273 K range. This paper presents the details of fabrication method and compares the thermoelectric properties with the properties of similar alloys manufactured by traditional vacuum casting and hot pressing.

  17. Characterization of Localized Filament Corrosion Products at the Anodic Head on a Model Mg-Zn-Zr Alloy Surface

    DOE PAGES

    Rossouw, David; Fu, Dong; Leonard, Donovan N.; ...

    2017-02-15

    In this study, localized filament corrosion products at the anodic head on a model Mg-1%Zn-0.4%Zr alloy surface were characterized by electron microscopy techniques of site-specific lamella prepared by focused ion beam milling. It is revealed that the anodic head propagates underneath a largely intact thin and dense MgO surface film and comprises dense aggregates of nano-crystalline MgO within a nano-porous Mg(OH)2 network. In conclusion, the findings contribute new supportive direct imaging insight into the source of the enhanced H2 evolution that accompanies anodic dissolution of Mg and its alloys.

  18. Photocurrent collection in a Schottky barrier on an amorphous silicon-germanium alloy structure with 1.23 eV optical gap

    NASA Astrophysics Data System (ADS)

    Chu, V.; Conde, J. P.; Shen, D. S.; Wagner, S.

    1989-07-01

    We report the result of voltage-dependent photocurrent collection measurements in Pd Schottky barriers on an undoped a-Si,Ge:H,F multilayer alloy structure with an effective optical gap of 1.23 eV. The hole mobility-lifetime product (μτ)p, extracted from a fit of the voltage dependence of the photocurrent to the Hecht expression, is 7×10-9 cm2 V-1. Our result is an important indication that it is possible to produce the low-gap a-Si,Ge:H,F alloys with the optoelectronic characteristics needed for efficient tandem solar cells.

  19. Energetics of gaseous and volatile fission products in molten U-10Zr alloy: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Wang, Ning; Tian, Jie; Jiang, Tao; Yang, Yanqiu; Hu, Sheng; Peng, Shuming; Yan, Liuming

    2015-11-01

    Gaseous and volatile fission products have a number of adverse effects on the safety and efficiency of the U-10Zr alloy fuel. The theoretical calculations were applied to investigate the energetics related to the formation, nucleation, and degassing of gaseous and volatile fission products (Kr, Xe and I) in molten U-10Zr alloy. The molecular dynamics (MD) simulations were applied to generate equilibrium configurations. The density functional theory (DFT) calculations were used to build atomistic models including molten U-10Zr alloy as well as its fission products substituted systems. The vacancy formation in liquid U-10Zr alloy were studied using DFT calculations, with average Gibbs free formation energies at 8.266 and 6.333 eV for U- and Zr-vacancies, respectively. And the interaction energies were -1.911 eV, -2.390 eV, and -1.826 eV for the I-I, Xe-Xe, and Kr-Kr interaction in lattice when two of the adjacent uranium atoms were substituted by gaseous atoms. So it could be concluded that the interaction between I, Kr, and Xe in lattice is powerful than the interaction between these two atoms and the other lattice atoms in U-10Zr.

  20. Production and fabrication of vanadium alloys for the radiative divertor program of DIII-D - Annual report input for 1996

    SciTech Connect

    Johnson, W.R.; Smith, J.P.; Stambaugh, R.D.

    1996-10-01

    V-4Cr-4Ti alloy has been selected for use in the manufacture of a portion of the DIII-D Radiative Divertor (RD) upgrade. The production of a 1200-kg ingot of V-4Cr-4Ti alloy has been completed at Teledyne Wah Chang of Albany, Oregon (TWCA) to provide {approximately}800-kg of applicable product forms, and two billets have been extruded from the ingot. Chemical compositions of the ingot and both extruded billets were acceptable. Material from these billets will be converted into product forms suitable for components of the DIII-D Radiative Divertor structure. Joining of V-4Cr-4Ti alloy has been identified as the most critical fabrication issue for its use in the RD Program, and research into several joining methods for fabrication of the RD components, including resistance seam, friction, and electron beam welding, is continuing. Preliminary trials have been successful in the joining of V-alloy to itself by electron beam, resistance, and friction welding processes and to Inconel 625 by friction welding.

  1. Production and blast-furnace smelting of boron-alloyed iron-ore pellets

    SciTech Connect

    A.A. Akberdin; A.S. Kim

    2008-08-15

    Industrial test data are presented regarding the production (at Sokolovsk-Sarbaisk mining and enrichment enterprise) and blast-furnace smelting (at Magnitogorsk metallurgical works) of boron-alloyed iron-ore pellets (500000 t). It is shown that, thanks to the presence of boron, the compressive strength of the roasted pellets is increased by 18.5%, while the strength in reduction is doubled; the limestone consumption is reduced by 11%, the bentonite consumption is halved, and the dust content of the gases in the last section of the roasting machines is reduced by 20%. In blast-furnace smelting, the yield of low-sulfur (<0.02%) hot metal is increased from 65-70 to 85.1% and the furnace productivity from 2.17-2.20 to 2.27 t/(m{sup 3} day); coke consumption is reduced by 3-8 kg/t of hot metal. The plasticity and stamping properties of 08IO auto-industry steel are improved by microadditions of boron.

  2. Overcoming residual stresses and machining distortion in the production of aluminum alloy satellite boxes.

    SciTech Connect

    Younger, Mandy S.; Eckelmeyer, Kenneth Hall

    2007-11-01

    Distortion frequently occurs during machining of age hardening aluminum alloys due to residual stresses introduced during the quenching step in the heat treatment process. This report quantifies, compares, and discusses the effectiveness of several methods for minimizing residual stresses and machining distortion in aluminum alloys 7075 and 6061.

  3. Continuous production of granular or powder Ti, Zr and Hf or their alloy products

    DOEpatents

    White, Jack C.; Oden, Laurance L.

    1993-01-01

    A continuous process for producing a granular metal selected from the group consisting of Ti, Zr or Hf under conditions that provide orderly growth of the metal free of halide inclusions comprising: a) dissolving a reducing metal selected from the group consisting of Na, Mg, Li or K in their respective halide salts to produce a reducing molten salt stream; b) preparing a second molten salt stream containing the halide salt of Ti, Zr or Hf; c) mixing and reacting the two molten streams of steps a) and b) in a continuous stirred tank reactor; d) wherein steps a) through c) are conducted at a temperature range of from about 800.degree. C. to about 1100.degree. C. so that a weight percent of equilibrium solubility of the reducing metal in its respective halide salt varies from about 1.6 weight percent at about 900.degree. C. to about 14.4 weight percent at about 1062.degree. C.; and wherein a range of concentration of the halide salt of Ti, Zn or Hf in molten halides of Na, Mg, Li or K is from about 1 to about 5 times the concentration of Na, Mg, Li or K; e) placing the reacted molten stream from step c) in a solid-liquid separator to recover an impure granular metal product by decantation, centrifugation, or filtration; and f) removing residual halide salt impurity by vacuum evaporator or inert gas sweep at temperatures from about 850.degree. C. to 1000.degree. C. or cooling the impure granular metal product to ambient temperature and water leaching off the residual metal halide salt.

  4. Production and Precipitation Hardening of Mg-Ca-Zn-Co Alloy for Tissue Engineering.

    PubMed

    Mutlu, Ilven

    2017-02-01

    In this study, Mg-Ca-Zn-Co alloy specimens for biomedical applications were produced by the powder metallurgy method. The Mg-Ca-Zn-Co alloy could be used as a scaffold material in tissue engineering applications. Electrochemical corrosion behavior of the specimens was investigated in simulated body fluid environment. Electrochemical corrosion resistance of the specimens was increased with increasing Zn and Ca contents of the alloy up to an optimum composition and then decreased. Optimum values for Ca and Zn additions were about 0.7 wt.% and 3.0 wt.% respectively. Young's modulus values of the specimens were determined by nondestructive ultrasonic measurement. Alloying element addition increased the Young's modulus of the specimens. Precipitation hardening of the Mg-Ca-Zn-Co alloy increased the Young's modulus and the corrosion rate of the specimens.

  5. Cost-Effective Method for Producing Self Supported Palladium Alloy Membranes for Use in Efficient Production of Coal Derived Hydrogen

    SciTech Connect

    K. Coulter

    2008-03-31

    Southwest Research Institute{reg_sign} (SwRI{reg_sign}) has utilized its expertise in large-area vacuum deposition methods to conduct research into the fabrication of dense, freestanding Pd-alloy membranes that are 3-5 microns thick and over 100 in{sup 2} in area. The membranes were deposited onto flexible and rigid supports that were subsequently removed and separated using novel techniques developed over the course of the project. Using these methods, the production of novel alloy compositions centered around the Pd-Cu system were developed with the objective of producing a thermally stable, nano-crystalline grain structure with the highest flux recorded as 242 SCFH/ft{sup 2} for a 2 {micro}m thick Pd{sub 53}Cu{sub 47} at 400 C and 20 psig feed pressure which when extrapolated is over twice the 2010 Department of Energy pure H{sub 2} flux target. Several membranes were made with the same permeability, but with different thicknesses and these membranes were highly selective. Researchers at the Colorado School of Mines supported the effort with extensive testing of experimental membranes as well as design and modeling of novel alloy composite structures. IdaTech provided commercial bench testing and analysis of SwRI-manufactured membranes. The completed deliverables for the project include test data on the performance of experimental membranes fabricated by vacuum deposition and several Pd-alloy membranes that were supplied to IdaTech for testing.

  6. Examination of an alternative method for the pyrometallurgical production of copper-chromium alloys

    NASA Astrophysics Data System (ADS)

    Brenk, J.; Hassan-Pour, S.; Spiess, P.; Friedrich, B.

    2016-07-01

    In this paper an alternative to the usual route for the production of copper-chromium alloys by Hot Isostatic Pressing (HIP) followed by Vacuum Arc Remelting (VAR) is investigated. Therefore the HIP is replaced by an aluminothermic reduction. As oxidizing agents for this aluminothermic reduction (ATR) chromium oxide (Cr2O3) and copper oxide (CuO) are used. These oxidants are mixed in a stoichiometric relation with aluminium (Al) to get the following aluminothermic reactions going: As ATRs always are exothermic reductions, it is important to control the heat output of the reaction. A common simplification for the heat calculation in the field of ATR is the “Shemshushny Factor” (Sh-Factor). This factor determines the rate of energy input per reactant mass: To avoid a secondary melt phase after ATR, inline casting is used to directly obtain vacuum arc remeltable electrodes out of the liquid melt of the ATR. The second part of this work deals with the remelting of these electrodes via VAR. The first VAR trials aim at finding process parameters for remelting a copper-chromium ingot. As demixing is to avoid, it is necessary to control process parameters within a small range to obtain a shallow melt pool.

  7. DFT study of the hexagonal high-entropy alloy fission product system

    NASA Astrophysics Data System (ADS)

    King, D. J. M.; Burr, P. A.; Obbard, E. G.; Middleburgh, S. C.

    2017-05-01

    The metallic phase fission product containing Mo-Pd-Rh-Ru-Tc can be described as a hexagonal high-entropy alloy (HEA) and is thus investigated using atomic scale simulation techniques relevant to HEAs. Contrary to previous assumptions, the removal of Tc from the system to form the Mo-Pd-Rh-Ru analog is predicted to reduce the stability of the solid solution to the point that σ-Mo5Ru3 may precipitate out at typical fuel operating temperatures. The drive for segregation is attributed to the increased stability of the solid solution with the ejection of Mo and Ru. When Tc is included in the system, a single phase hexagonal solid solution is expected to form for a wider range of compositions. Furthermore, when cooled below 700 °C, this single phase solid solution is predicted to transition to a partially ordered structure. Future studies using the Tc-absent analogue will need to take these structural and chemical deliberations into consideration.

  8. Silicon purification using a Cu-Si alloy source

    NASA Technical Reports Server (NTRS)

    Powell, R. C.; Tejedor, P.; Olson, J. M.

    1986-01-01

    Production of 99.9999% pure silicon from 98% pure metallurgical grade (MG) silicon by a vapor transport filtration process (VTP) is described. The VTF process is a cold wall version of an HCl chemical vapor transport technique using a Si:Cu3Si alloy as the silicon source. The concentration, origin, and behavior of the various impurities involved in the process were determined by chemically analyzing alloys of different purity, the slag formed during the alloying process, and the purified silicon. Atomic absorption, emission spectrometry, inductively coupled plasma, spark source mass spectrometry, and secondary ion mass spectroscopy were used for these analyses. The influence of the Cl/H ratio and the deposition temperature on the transport rate was also investigated.

  9. Production of Gas-Solid Structures in Aluminum and Nickel Alloys by Gasar Processing

    SciTech Connect

    Apprill, J.M.; Baldwin, M.D.; Maguire, M.C.; Miszkiel, M.E.; Shapovalov, V.I.

    1999-01-06

    Experimental data on directional and bulk solidification of hydrogen-charged samples of aluminum alloy A356 and nickel alloy Inconel 718 are discussed. The solidification structure of the porous zone is shown to be dependent on many process variables. Of these variables, hydrogen content in the melt prior to solidification, and furnace atmospheric pressure during solidification play the decisive role. Also important are the furnace atmosphere composition, the solidification velocity, and the temperature distribution of the liquid metal inside the mold.

  10. Purification of uranium alloys by differential solubility of oxides and production of purified fuel precursors

    DOEpatents

    McLean, II, William; Miller, Philip E.

    1997-01-01

    A method for purifying metallic alloys of uranium for use as nuclear reactor fuels in which the metal alloy is first converted to an oxide and then dissolved in nitric acid. Initial removal of metal oxide impurities not soluble in nitric acid is accomplished by filtration or other physical means. Further purification can be accomplished by carbonate leaching of uranyl ions from the partially purified solution or using traditional methods such as solvent extraction.

  11. Purification of uranium alloys by differential solubility of oxides and production of purified fuel precursors

    DOEpatents

    McLean, W. II; Miller, P.E.

    1997-12-16

    A method is described for purifying metallic alloys of uranium for use as nuclear reactor fuels in which the metal alloy is first converted to an oxide and then dissolved in nitric acid. Initial removal of metal oxide impurities not soluble in nitric acid is accomplished by filtration or other physical means. Further purification can be accomplished by carbonate leaching of uranyl ions from the partially purified solution or using traditional methods such as solvent extraction. 3 figs.

  12. DC Electric Arc Furnace Application for Production of Nickel-Boron Master Alloys

    NASA Astrophysics Data System (ADS)

    Alkan, Murat; Tasyürek, Kerem Can; Bugdayci, Mehmet; Turan, Ahmet; Yücel, Onuralp

    2017-07-01

    In this study, nickel-boron (Ni-B) alloys were produced via a carbothermic reduction starting from boric acid (H3BO3) with high-purity nickel oxide (NiO), charcoal, and wood chips in a direct current arc furnace. In electric arc furnace experiments, different starting mixtures were used, and their effects on the chemical compositions of the final Ni-B alloys were investigated. After the reduction and melting stages, Ni-B alloys were obtained by tapping from the bottom of the furnace. The samples from the designated areas were also taken and analyzed. The chemical composition of the final alloys and selected samples were measured with wet chemical analysis. The Ni-B alloys had a composition of up to 14.82 mass% B. The phase contents of the final alloys and selected samples were measured using x-ray diffraction (XRD). The XRD data helped predict possible reactions and reaction mechanisms. The material and energy balance calculations were made via the XRD Rietveld and chemical compositions. Nickel boride phases started to form 600 mm below the surface. The targeted NiB phase was detected at the tapping zone of the crucible (850-900 mm depth). The energy consumption was 1.84-4.29 kWh/kg, and the electrode consumption was 10-12 g/kg of raw material charged.

  13. DC Electric Arc Furnace Application for Production of Nickel-Boron Master Alloys

    NASA Astrophysics Data System (ADS)

    Alkan, Murat; Tasyürek, Kerem Can; Bugdayci, Mehmet; Turan, Ahmet; Yücel, Onuralp

    2017-09-01

    In this study, nickel-boron (Ni-B) alloys were produced via a carbothermic reduction starting from boric acid (H3BO3) with high-purity nickel oxide (NiO), charcoal, and wood chips in a direct current arc furnace. In electric arc furnace experiments, different starting mixtures were used, and their effects on the chemical compositions of the final Ni-B alloys were investigated. After the reduction and melting stages, Ni-B alloys were obtained by tapping from the bottom of the furnace. The samples from the designated areas were also taken and analyzed. The chemical composition of the final alloys and selected samples were measured with wet chemical analysis. The Ni-B alloys had a composition of up to 14.82 mass% B. The phase contents of the final alloys and selected samples were measured using x-ray diffraction (XRD). The XRD data helped predict possible reactions and reaction mechanisms. The material and energy balance calculations were made via the XRD Rietveld and chemical compositions. Nickel boride phases started to form 600 mm below the surface. The targeted NiB phase was detected at the tapping zone of the crucible (850-900 mm depth). The energy consumption was 1.84-4.29 kWh/kg, and the electrode consumption was 10-12 g/kg of raw material charged.

  14. Commercialization of multijunction a-Si modules

    NASA Astrophysics Data System (ADS)

    Carlson, D. E.; Arya, R. R.; Chen, L.-F.; Oswald, R.; Newton, J.; Rajan, K.; Romero, R.; Willing, F.; Yang, L.

    1997-02-01

    Solarex has just completed building a plant in James City County, Virginia that has the capacity to produce 10 MW per year of multijunction amorphous silicon PV modules. The plant will start commercial production of 8.6 ft2 tandem modules in early 1997. The tandem device structure consists of two stacked p-i-n junctions, a front junction containing amorphous silicon and a back junction containing an amorphous silicon germanium alloy. All amorphous silicon alloys are deposited using plasma-enhanced chemical vapor deposition, and the large-area monolithic modules are interconnected using computerized laser scribing coupled with a machine vision system. The principle products will be monolithic modules (26″×48″) with nominal stabilized power ratings of 56, 50 and 43 peak watts. All modules will be fabricated using a glass-EVA-glass encapsulation to ensure long-term reliability. These products are expected to be widely used in both remote and grid-tied applications.

  15. Risks of beryllium disease related to work processes at a metal, alloy, and oxide production plant.

    PubMed Central

    Kreiss, K; Mroz, M M; Zhen, B; Wiedemann, H; Barna, B

    1997-01-01

    OBJECTIVES: To describe relative hazards in sectors of the beryllium industry, risk factors of beryllium disease and sensitisation related to work process were sought in a beryllium manufacturing plant producing pure metal, oxide, alloys, and ceramics. METHODS: All 646 active employees were interviewed; beryllium sensitisation was ascertained with the beryllium lymphocyte proliferation blood test on 627 employees; clinical evaluation and bronchoscopy were offered to people with abnormal test results; and industrial hygiene measurements related to work processes taken in 1984-93 were reviewed. RESULTS: 59 employees (9.4%) had abnormal blood tests, 47 of whom underwent bronchoscopy. 24 new cases of beryllium disease were identified, resulting in a beryllium disease prevalence of 4.6%, including five known cases (29/632). Employees who had worked in ceramics had the highest prevalence of beryllium disease (9.0%). Employees in the pebble plant (producing beryllium metal) who had been employed after 1983 also had increased risk, with a prevalence of beryllium disease of 6.4%, compared with 1.3% of other workers hired in the same period, and a prevalence of abnormal blood tests of 19.2%. Logistic regression modelling confirmed these two risk factors for beryllium disease related to work processes and the dependence on time of the risk at the pebble plant. The pebble plant was not associated with the highest gravimetric industrial hygiene measurements available since 1984. CONCLUSION: Further characterisation of exposures in beryllium metal production may be important to understanding how beryllium exposures confer high contemporary risk of beryllium disease. PMID:9326165

  16. Corrosion resistance of alumina forming alloys against molten chlorides for energy production. II: Electrochemical impedance spectroscopy under thermal cycling conditions

    DOE PAGES

    Gomez-Vidal, Judith C.; Fernandez, A. G.; Tirawat, R.; ...

    2017-04-01

    Next-generation power systems require higher temperatures to increase the efficiency of electricity production in the power block. Concentrating solar power (CSP) technology is looking for high temperature thermal fluids able to work in the range of 550–750 °C. Molten chlorides containing NaCl, KCl, MgCl2, and/or ZnCl2 are being considered for solar receivers and/or sensible- or latent- thermal energy storage systems. Vapor pressures of chlorides are high enough that in combination with oxygen gaseous compounds will produce a harsh atmosphere that is generally very aggressive to common chromia forming alloys. Corrosion mitigations must consider a solution in which both zones (immersedmore » in fluid and exposed to vapor phase) will be protected. This could easily be obtained using alloy surface modification approaches. Surface passivation, produced after pre-oxidation treatments, of alumina forming alloys (Inconel 702, Haynes 224 and Kanthal APMT) was evaluated in molten 35.59 wt% MgCl2 – 64.41 wt% KCl thermally cycled from 550 °C to 700 °C in flowing Ar and static zero air (ZA) atmospheres. Electrochemical impedance spectroscopy tests and metallographic characterization showed that the best performing alloy was pre-oxidized In702 in ZA at 1050 °C for 4 h due to the formation of protective, dense and continuous alumina layers. The alumina layers were unstable when flowing Ar was used as the inert atmosphere during corrosion evaluations. Corrosion results in static ZA are promising for next-generation CSP applications using molten chlorides because alumina scales were stable after 185 h of immersion in the oxygen-containing atmosphere. Alumina layers in pre-oxidized Al-FA In702 grew from 5 µm (before immersion) to 13 µm (after 185 h of immersion). As a result, the use of these alloys could be commercial feasibility and cost-effective because of the possibility of using oxygen-containing atmospheres instead of keeping enclosed systems with inert

  17. Near-Net-Shape Production of Hollow Titanium Alloy Components via Electrochemical Reduction of Metal Oxide Precursors in Molten Salts

    NASA Astrophysics Data System (ADS)

    Hu, Di; Xiao, Wei; Chen, George Z.

    2013-04-01

    Metal oxide precursors (ca. 90 wt pct Ti, 6 wt pct Al, and 4 wt pct V) were prepared with a hollow structure in various shapes such as a sphere, miniature golf club head, and cup using a one-step solid slip-casting process. The precursors were then electro-deoxidized in molten calcium chloride [3.2 V, 1173 K (900 °C)] against a graphite anode. After 24 hours of electrolysis, the near-net-shape Ti-6Al-4V product maintained its original shape with controlled shrinkage. Oxygen contents in the Ti-6Al-4V components were typically below 2000 ppm. The maximum compressive stress and modulus of electrolytic products obtained in this work were approximately 243 MPa and 14 GPa, respectively, matching with the requirement for medical implants. Further research directions are discussed for mechanical improvement of the products via densification during or after electrolysis. This simple, fast, and energy-efficient near-net-shape manufacturing method could allow titanium alloy components with desired geometries to be prepared directly from a mixture of metal oxides, promising an innovative technology for the low-cost production of titanium alloy components.

  18. Characterization of corrosion products of AB{sub 5}-type hydrogen storage alloys for nickel-metal hydride batteries

    SciTech Connect

    Maurel, F.; Knosp, B.; Backhaus-Ricoult, M.

    2000-01-01

    To better understand the decrease in storage capacity of AB{sub 5}-type alloys in rechargeable Ni/MH batteries undergoing repeated charge/discharge cycles, the corrosion of a MnNi{sub 3.55}Co{sub 0.75}Mn{sub 0.4}Al{sub 0.3} alloy in aqueous KOH electrolyte was studied. The crystal structure, chemical composition, and distribution of corrosion products were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Hollow and filed needles of a mixed rare earth hydroxide Mn(OH){sub 3} were found to cover a continuous nanocrystalline corrosion scale composed of metal (Ni, Co) solid solution, oxide (Ni,Co)O solid solution and rare earth hydroxide, and a Mn-depleted alloy subscale. Corrosion kinetics were measured for three different temperatures. Growth kinetics of the continuous corrosion scale and of the Mm(OH){sub 3} needles obeyed linear and parabolic rate laws, respectively. Models for the corrosion mechanism were developed on the basis of diffusional transport of Mn and OH through the hydroxide needles and subsequent diffusion along grain boundaries through the nanocrystalline scale.

  19. Synthesis of Ge nanocrystals embedded in a Si host matrix

    NASA Astrophysics Data System (ADS)

    Ngiam, Shih-Tung; Jensen, Klavs F.; Kolenbrander, K. D.

    1994-12-01

    The synthesis of a composite material consisting of Ge nanoclusters (greater than or equal to 2 nm in diameter) embedded in a Si host matrix is reported. The Ge nanoparticles are produced by pulsed laser ablation and are codeposited in a Si film simultaneously grown by chemical beam epitaxy using disilane. Scanning transmission electron microscopy, combined with energy-dispersive x-ray measurements, show that discrete Ge particles (greater than or equal to 2 nm diameter) are deposited within a polycrystalline Si host matrix. High-resolution transmission electron microscopy reveals that the paricles are crystalline with a lattice spacing corresponding to that of Ge. The enhancement of Si deposition rates from silanes in the presence of Ge, previously demonstrated in chemical vapor deposition of Si(1 - x)Ge(x) alloys, is shown to facilitate the growth of a Si layer around the Ge nanocrystals. The overall composition of the Ge cluster/Si host composite material is determined by Rutherford backscattering measurements.

  20. Turbine Blade Alloy

    NASA Technical Reports Server (NTRS)

    MacKay, Rebecca

    2001-01-01

    The High Speed Research Airfoil Alloy Program developed a fourth-generation alloy with up to an +85 F increase in creep rupture capability over current production airfoil alloys. Since improved strength is typically obtained when the limits of microstructural stability are exceeded slightly, it is not surprising that this alloy has a tendency to exhibit microstructural instabilities after high temperature exposures. This presentation will discuss recent results obtained on coated fourth-generation alloys for subsonic turbine blade applications under the NASA Ultra-Efficient Engine Technology (UEET) Program. Progress made in reducing microstructural instabilities in these alloys will be presented. In addition, plans will be presented for advanced alloy development and for computational modeling, which will aid future alloy development efforts.

  1. Effect of V Precipitation on Continuously Cooled Sulfur-Lean Vanadium-Alloyed Steels for Long Products Applications

    NASA Astrophysics Data System (ADS)

    Capdevila, C.; García-Mateo, C.; Cornide, J.; Chao, J.; Caballero, F. G.

    2011-12-01

    The acicular ferrite formation as decomposition product of S-lean V-alloyed austenite with high N content is studied in this article. A combination of thermodynamic models as well as some physical metallurgical principles was used to analyze the intragranular nucleation potency of V(C,N) precipitates. The designed thermomechanical and heat treatments ensure an almost homogeneous microstructure consisting of acicular ferrite for this N-rich laboratory cast steel. The results presented in this work demonstrate that, in the absence of sulfide inclusions, acicular ferrite is nucleated on V(C,N) precipitates.

  2. Photovoltaic semiconductor materials based on alloys of tin sulfide, and methods of production

    DOEpatents

    Lany, Stephan

    2016-06-07

    Photovoltaic thin-film materials comprising crystalline tin sulfide alloys of the general formula Sn.sub.1-x(R).sub.xS, where R is selected from magnesium, calcium and strontium, as well as methods of producing the same, are disclosed.

  3. ELLIPSOMETRIC STUDY OF a-Si:H NUCLEATION, GROWTH, AND INTERFACES

    NASA Astrophysics Data System (ADS)

    Collins, R. W.

    Recent in situ and spectroscopic ellipsometry investigations of hydrogenated amorphous silicon (a-Si:H) nucleation behavior, microstructural evolution, and interface formation are reviewed. An outline of the commonly applied experimental techniques and data analysis is also presented. In situ ellipsometry reveals a nuclei formation and convergence sequence in the first 50Å of a-Si:H growth by rf plasma deposition from silane on c-Si and metal substrates. This sequence provides evidence of favorable growth chemistry that results in material with a low density of structural defects. The influence of deposition parameters and processes on the nucleation and subsequent microstructural evolution of a-Si:H is covered in detail. Among the other topics discussed include: nucleation of microcrystalline Si, evolution of surface roughness on a-Si:H, inert and reactive gas plasma modification of a-Si:H, and formation of a-Si:H heterostructures with SiO2, wide band gap alloys, and Bdoped a-Si:H.

  4. EFFECT OF JP-5 SULFUR CONTENT ON HOT CORROSION OF SUPER ALLOYS IN MARINE ENVIRONMENT.

    DTIC Science & Technology

    SULFUR, AVIATION FUELS), (*NICKEL ALLOYS , CORROSION), (*COBALT ALLOYS , CORROSION), (*CORROSION, AVIATION FUELS), ENVIRONMENTAL TESTS, SEA WATER...GAS TURBINE BLADES, AIRCRAFT ENGINES, CORROSION RESISTANT ALLOYS , COMBUSTION PRODUCTS, CHROMIUM ALLOYS , MOLYBDENUM ALLOYS , TUNGSTEN ALLOYS , ALUMINUM... ALLOYS , ALUMINUM COATINGS, ANALYSIS OF VARIANCE, TITANIUM ALLOYS , EXPERIMENTAL DATA, STATISTICAL ANALYSIS

  5. Production of chromium base alloys by ball milling in hydrogen iodide

    NASA Technical Reports Server (NTRS)

    Arias, A.

    1975-01-01

    The effects of processing variables on the tensile properties and ductile-to-brittle transition temperature (DBTT) of Cr + 4 vol% ThO2 alloys and of pure Cr produced by ball milling in hydrogen iodide were investigated. Hot rolled Cr + ThO2 was stronger than either hot pressed Cr + ThO2 or pure Cr at temperatures up to 1540 C. Hot pressed Cr + ThO2 had a DBTT of 500 C as compared with -8 to 24 C for the hot rolled Cr + ThO2 and with 140 C for pure Cr. It is postulated that the dispersoid in the hot rolled alloys lowers the DBTT by inhibiting recovery and recrystallization of the strained structure.

  6. Production of chromium base alloys by ball milling in hydrogen iodide

    NASA Technical Reports Server (NTRS)

    Arias, A.

    1975-01-01

    The effects of processing variables on the tensile properties and ductile-to-brittle transition temperature (DBTT) of Cr + 4 vol% ThO2 alloys and of pure Cr produced by ball milling in hydrogen iodide were investigated. Hot rolled Cr + ThO2 was stronger than either hot pressed Cr + ThO2 or pure Cr at temperatures up to 1540 C. Hot pressed Cr + ThO2 had a DBTT of 500 C as compared with -8 to 24 C for the hot rolled Cr + ThO2 and with 140 C for pure Cr. It is postulated that the dispersoid in the hot rolled alloys lowers the DBTT by inhibiting recovery and recrystallization of the strained structure.

  7. Sintering of the reaction products of combustion of alloys in nitrogen

    SciTech Connect

    Maksimov, Y.M.; Raskolenko, L.G.; Zepakova, O.K.; Ziatdinov, M.K.

    1986-05-01

    An investigation of the mechanism of compacting of Fe-V alloy with a sigma-phase structure, a low porosity composite material consisting of alpha-iron and a filler of delta-vanadium nitride, is made after the synthesis surge. Alloys containing 50 wt.% Fe were prepared by sintering in a vacuum furnace of powders of type VEL-1 vandium and special purity carbonyl iron. The mechanism of compacting was studied on specimens in hardened water. Metallographic investigations were made on MIM-7 and PMT-3 instruments and the phase analysis on a DRON-2 instrument. Rapid compacting in combustion of sigma-FeV in nitrogen is determined by combining of the solid-liquid drops formed in the combustion front and consisting of molten iron and vanadium nitrides.

  8. Induction heat treatment and technique of bioceramic coatings production on medical titanium alloys

    NASA Astrophysics Data System (ADS)

    Fomin, Aleksandr A.; Rodionov, Igor V.; Fomina, Marina A.; Poshivalova, Elena Y.; Krasnikov, Aleksandr V.; Petrova, Natalia N.; Zakharevich, Andrey M.; Skaptsov, Alexander A.; Gribov, Andrey N.; Atkin, Vsevolod S.

    2015-03-01

    Prospective composite bioceramic titania coatings were obtained on intraosseous implants fabricated from medical titanium alloy VT16 (Ti-2.5Al-5Mo-5V). Consistency changes of morphological characteristics, physico-mechanical properties and biocompatibility of experimental titanium implant coatings obtained by oxidation during induction heat treatment are defined. Technological recommendations for obtaining bioceramic coatings with extremely high strength on titanium items surface are given.

  9. Regenerability of hydrotalcite-derived nickel-iron alloy nanoparticles for syngas production from biomass tar.

    PubMed

    Li, Dalin; Koike, Mitsuru; Wang, Lei; Nakagawa, Yoshinao; Xu, Ya; Tomishige, Keiichi

    2014-02-01

    Nickel-iron/magnesium/aluminum bimetallic catalysts were prepared by the calcination and reduction of nickel-magnesium-iron-aluminum hydrotalcite-like compounds. Characterization suggests that, at iron/nickel≤0.5, both nickel and iron species are homogeneously distributed in the hydrotalcite precursor and incorporated into the Mg(Ni, Fe, Al)O periclase after calcination, giving rise to uniform nickel-iron alloy nanoparticles after reduction. Ni-Fe/Mg/Al (Fe/Ni=0.25) exhibits the best catalytic performance for the steam reforming of tar derived from the pyrolysis of biomass. It is suggested that the uniform nickel-iron alloy nanoparticles and the synergy between nickel and iron are responsible for the high catalytic performance. Moreover, the Ni-Fe/Mg/Al catalyst exhibits much better regenerability toward oxidation-reduction treatment for the removal of deposited coke than that of conventional Ni-Fe/α-Al2 O3 . This property can be attributed to the better regeneration of Ni-Fe alloy nanoparticles through the formation and reduction of Mg(Ni, Fe, Al)O. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Removing hydrochloric acid exhaust products from high performance solid rocket propellant using aluminum-lithium alloy.

    PubMed

    Terry, Brandon C; Sippel, Travis R; Pfeil, Mark A; Gunduz, I Emre; Son, Steven F

    2016-11-05

    Hydrochloric acid (HCl) pollution from perchlorate based propellants is well known for both launch site contamination, as well as the possible ozone layer depletion effects. Past efforts in developing environmentally cleaner solid propellants by scavenging the chlorine ion have focused on replacing a portion of the chorine-containing oxidant (i.e., ammonium perchlorate) with an alkali metal nitrate. The alkali metal (e.g., Li or Na) in the nitrate reacts with the chlorine ion to form an alkali metal chloride (i.e., a salt instead of HCl). While this technique can potentially reduce HCl formation, it also results in reduced ideal specific impulse (ISP). Here, we show using thermochemical calculations that using aluminum-lithium (Al-Li) alloy can reduce HCl formation by more than 95% (with lithium contents ≥15 mass%) and increase the ideal ISP by ∼7s compared to neat aluminum (using 80/20 mass% Al-Li alloy). Two solid propellants were formulated using 80/20 Al-Li alloy or neat aluminum as fuel additives. The halide scavenging effect of Al-Li propellants was verified using wet bomb combustion experiments (75.5±4.8% reduction in pH, ∝ [HCl], when compared to neat aluminum). Additionally, no measurable HCl evolution was detected using differential scanning calorimetry coupled with thermogravimetric analysis, mass spectrometry, and Fourier transform infrared absorption. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Characterization of Discontinuous Coarsening Reaction Products in INCONEL® Alloy 740H® Fusion Welds

    NASA Astrophysics Data System (ADS)

    Bechetti, Daniel H.; Dupont, John N.; Watanabe, Masashi; de Barbadillo, John J.

    2017-04-01

    Characterization of γ' coarsened zones (CZs) in alloy 740H fusion welds via a variety of electron microscopy techniques was conducted. The effects of solute partitioning during nonequilibrium solidification on the amount of strengthening precipitates along the grain boundaries were evaluated via electron-probe microanalysis and scanning electron microscopy. Electron backscatter diffraction was used to present evidence for the preferential growth of CZs toward regions of lower γ' content, even if growth in that direction increases grain boundary area. Scanning electron microscopy and image analysis were used to quantify the propensity for CZs to develop along certain segments of the grain boundaries, as governed by the local variations in γ' content. Scanning transmission electron microscopy with X-ray energy-dispersive spectrometry (XEDS) was used to assess the compositions of the matrix and precipitate phases within the CZs and to quantify the segregation of alloying components to the reaction front. Thermodynamic and kinetic modeling were used to compare calculated and experimental compositions. The work presented here provides new insight into the progression of the discontinuous coarsening (DC) reaction in a complex engineering alloy.

  12. Characterization of Discontinuous Coarsening Reaction Products in INCONEL® Alloy 740H® Fusion Welds

    NASA Astrophysics Data System (ADS)

    Bechetti, Daniel H.; Dupont, John N.; Watanabe, Masashi; de Barbadillo, John J.

    2017-02-01

    Characterization of γ' coarsened zones (CZs) in alloy 740H fusion welds via a variety of electron microscopy techniques was conducted. The effects of solute partitioning during nonequilibrium solidification on the amount of strengthening precipitates along the grain boundaries were evaluated via electron-probe microanalysis and scanning electron microscopy. Electron backscatter diffraction was used to present evidence for the preferential growth of CZs toward regions of lower γ' content, even if growth in that direction increases grain boundary area. Scanning electron microscopy and image analysis were used to quantify the propensity for CZs to develop along certain segments of the grain boundaries, as governed by the local variations in γ' content. Scanning transmission electron microscopy with X-ray energy-dispersive spectrometry (XEDS) was used to assess the compositions of the matrix and precipitate phases within the CZs and to quantify the segregation of alloying components to the reaction front. Thermodynamic and kinetic modeling were used to compare calculated and experimental compositions. The work presented here provides new insight into the progression of the discontinuous coarsening (DC) reaction in a complex engineering alloy.

  13. Effectivity of fluoride treatment on hydrogen and corrosion product generation in temporal implants for different magnesium alloys.

    PubMed

    Trinidad, Javier; Arruebarrena, Gurutze; Marco, Iñigo; Hurtado, Iñaki; Sáenz de Argandoña, Eneko

    2013-12-01

    The increasing interest on magnesium alloys relies on their biocompatibility, bioabsorbility and especially on their mechanical properties. Due to these characteristics, magnesium alloys are becoming a promising solution to be used, as temporary implants. However, magnesium alloys must overcome their poor corrosion resistance. This article analyses the corrosion behaviour in phosphate-buffered saline solution of three commercial magnesium alloys (AZ31B, WE43 and ZM21) as well as the influence of fluoride treatment on their corrosion behaviour. It is shown that the corrosion rate of all the alloys is decreased by fluoride treatment. However, fluoride treatment affects each alloy differently.

  14. Production and properties of INCOLOY{reg_sign} alloy 908 tubing for sheathing of Nb{sub 3}Sn superconducting cables

    SciTech Connect

    Weber, J.H.; Poole, J.M.

    1997-06-01

    INCOLOY alloy 908 is a controlled thermal expansion, age-hardenable alloy developed for Nb{sub 3}Sn cable-in-conduit sheathing applications. It has been specified for the International Thermonuclear Experimental Reactor (ITER) model superconducting magnet coils and is being considered for other similar applications. Overviews of the production sequences for several types of tubing for sheathing are presented. Supporting studies, such as hot ductility, work hardening behavior, and heat treatment responses, used to develop the production schemes are also described. Finally, example properties of the tubing are presented and discussed.

  15. Binary synaptic connections based on memory switching in a-Si:H for artificial neural networks

    NASA Technical Reports Server (NTRS)

    Thakoor, A. P.; Lamb, J. L.; Moopenn, A.; Khanna, S. K.

    1987-01-01

    A scheme for nonvolatile associative electronic memory storage with high information storage density is proposed which is based on neural network models and which uses a matrix of two-terminal passive interconnections (synapses). It is noted that the massive parallelism in the architecture would require the ON state of a synaptic connection to be unusually weak (highly resistive). Memory switching using a-Si:H along with ballast resistors patterned from amorphous Ge-metal alloys is investigated for a binary programmable read only memory matrix. The fabrication of a 1600 synapse test array of uniform connection strengths and a-Si:H switching elements is discussed.

  16. Binary synaptic connections based on memory switching in a-Si:H for artificial neural networks

    NASA Technical Reports Server (NTRS)

    Thakoor, A. P.; Lamb, J. L.; Moopenn, A.; Khanna, S. K.

    1987-01-01

    A scheme for nonvolatile associative electronic memory storage with high information storage density is proposed which is based on neural network models and which uses a matrix of two-terminal passive interconnections (synapses). It is noted that the massive parallelism in the architecture would require the ON state of a synaptic connection to be unusually weak (highly resistive). Memory switching using a-Si:H along with ballast resistors patterned from amorphous Ge-metal alloys is investigated for a binary programmable read only memory matrix. The fabrication of a 1600 synapse test array of uniform connection strengths and a-Si:H switching elements is discussed.

  17. Influence of noble metal fission products and uranium on the microstructure and corrosion behaviour of D9 stainless steel-zirconium metal waste form alloy

    NASA Astrophysics Data System (ADS)

    Bairi, Lipika Rani; Mallika, C.; Kamachi Mudali, U.

    2014-05-01

    Metal waste form (MWF) alloys of composition D9SS-8.5Zr, D9SS-10Zr-1NMFP and D9SS-10Zr-1NMFP-10U were prepared by casting of D9SS (Ti-modified austenitic 316 stainless steel), zirconium, NMFPs (noble metal fission products) and uranium for evaluating the influence of NMFPs and U on the microstructure and corrosion resistance of MWF alloys. Gradual increase in the hardness value was observed with the addition of NMFPs and uranium. Microstructural characterisation revealed the formation of Zr-rich intermetallic phases in these alloys which act as hosts for NMFPs and U. Fe-Zr and Ni-Zr based intermetallics were identified in D9SS-Zr and D9SS-Zr-NMFP alloys by XRD technique. In the U added alloy, UZrO2 and NiU2 were observed along with Fe-Zr and Ni-Zr intermetallics. Electrochemical corrosion monitoring confirmed active corrosion potential and higher passive current density with the addition of NMFPs and U. The MWF alloy with NMFPs showed higher break down potential with high polarization resistance revealing stable passive film.

  18. Establishment of a Plasma Melting Manufacturing Process for Production of Nickel-Base Alloys.

    DTIC Science & Technology

    1975-05-01

    surrounding the arc with cold walls capable of wi thstanc’ing high heat flux and/or surrounding the arc with a cold liquid or gas. The gas is forced to flow...considerations, contractural obligations, or notice on a specific document. This final report was submitted by Carnegie-Mellon Institute of Research...argon gas plasmarc has been shown to be a useful high heat source for melt-consolidatm i of super alloy and types of scrap including reactive metal

  19. Regularities of crystallographic texture formation in cladding tubes from Zr-based alloys during their production

    NASA Astrophysics Data System (ADS)

    Isaenkova, M.; Perlovich, Yu; Fesenko, V.

    2016-04-01

    This paper summarizes researches of the authors, which are directed on the development of the methodological basis of X-ray studies in the materials science of zirconium and on the systematization of new experimental results obtained using developed methods. The paper describes regularities of the formation of the crystallographic texture and the substructure inhomogeneity of cladding tubes from zirconium alloys at various stages of their manufacturing, i.e. during hot and cold deformation, recrystallization, phase transformations and interactions of the above processes.

  20. Catalyst Alloys Processing

    NASA Astrophysics Data System (ADS)

    Tan, Xincai

    2014-10-01

    Catalysts are one of the key materials used for diamond formation at high pressures. Several such catalyst products have been developed and applied in China and around the world. The catalyst alloy most widely used in China is Ni70Mn25Co5 developed at Changsha Research Institute of Mining and Metallurgy. In this article, detailed techniques for manufacturing such a typical catalyst alloy will be reviewed. The characteristics of the alloy will be described. Detailed processing of the alloy will be presented, including remelting and casting, hot rolling, annealing, surface treatment, cold rolling, blanking, finishing, packaging, and waste treatment. An example use of the catalyst alloy will also be given. Industrial experience shows that for the catalyst alloy products, a vacuum induction remelt furnace can be used for remelting, a metal mold can be used for casting, hot and cold rolling can be used for forming, and acid pickling can be used for metal surface cleaning.

  1. A SiGe/Si multiple quantum well avalanche photodetector

    NASA Astrophysics Data System (ADS)

    Sun, Po-Hsing; Chang, Shu-Tong; Chen, Yu-Chun; Lin, Hongchin

    2010-10-01

    The present work investigates the performance of APDs with a SiGe/Si multi-quantum well (MQW) structure, which was fabricated using ultrahigh-vacuum chemical vapor deposition (UHV/CVD). Absorption of radiation and avalanche multiplication occur in both SiGe/Si MQW and the i-SiGe layer. Intense photoluminescence (PL) from strained, epitaxial SiGe alloys grown using UHV/CVD was reported with multiple SiGe/Si MQW and i-SiGe layer. It was found that the avalanche multiplication occurred at about 7 V, when exceeding 7 V, the responsiveness and quantum efficiency rapidly increased. An APD consisting of an epitaxial SiGe/Si MQW as the active absorption layer with intense response in the 800-1500 nm wavelength range is also demonstrated.

  2. Low activation ferritic alloys

    DOEpatents

    Gelles, D.S.; Ghoniem, N.M.; Powell, R.W.

    1985-02-07

    Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

  3. Low activation ferritic alloys

    DOEpatents

    Gelles, David S.; Ghoniem, Nasr M.; Powell, Roger W.

    1986-01-01

    Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

  4. Direct production of nanostructured copper-nickel (Cu-Ni) alloy particles

    SciTech Connect

    Apaydin, Ramazan Oguzhan; Ebin, Burcak; Gurmen, Sebahattin

    2013-12-16

    Copper-Nickel (CuNi) nanostructured alloy particles were produced by Ultrasonic Spray Pyrolysis and Hydrogen Reduction Method (USP-HR) from high purity copper and nickel nitrate aqueous solutions. The effect of the precursor solution in the range of 0.1 and 0.5 mol/L on the morphology and crystallite size of CuNi nanoparticles were investigated under 2 h running time, 700 °C operating temperature and 0.5 L/min H{sub 2} flow rate. Particle size, morphology, composition and crystallite structure were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-Ray Diffraction (XRD). Particle characterization studies show that nanostructured alloy particles have cubic crystal structure and they are in submicron size range with spherical morphology. The crystallite sizes of the particles calculated with Scherrer formula are 40 and 34 nm and average particles sizes observed from the SEM images are 300 and 510 nm for each experiment respectively.

  5. Improved model to predict properties of aluminum alloy products after continuous cooling

    SciTech Connect

    Doherty, R.D. ); Staley, J.T.; Jaworski, A.P. )

    1993-11-01

    Previous models of quench sensitivity of age-hardening alloys have been extended to include loss of toughness as well as loss of yield strength upon postquench aging. Loss of toughness on slow quenching was modeled by the loss of solute to grain-boundary precipitates that promote intergranular fracture. The phenomena are modeled using differential equations, and the model includes temperature-dependent values of the minimum toughness and strength expected after extended isothermal hold times. Time-temperature-property (TTP) curves for the postaging yield strength and toughness were used to provide empirical kinetic and property data for fitting the proposed relationship. The model was tested against experimental data, both nominally isothermal and truly continuous cooling, for an Al-Cu-Li alloy plate. For nominally isothermally cooling, the model proved to be capable of accurately describing the loss of toughness and the loss of strength to a much larger loss in strength than previous models. The model also successfully predicted the loss of strength on continuous cooling but provided a conservative overestimate of the loss of toughness under the same continuous-cooling conditions. It is suggested that this bias arises from the lack of consideration of differences in the microstructure of the precipitates formed during isothermal treatments and those formed during continuous cooling.

  6. Effect of the production technology of bolts from Ti-Al-Mo-V alloy on the heterogeneity of their texture and susceptibility to the fracture

    NASA Astrophysics Data System (ADS)

    Perlovich, Yu. A.; Isaenkova, M. G.; Krymskaya, O. A.; Fesenko, V. A.; Medvedev, P. N.

    2016-10-01

    The paper considers the formation of crystallographic texture inhomogeneity along the length of bolts from titanium alloy due to the difference of the deformation scheme used by production of bolt head and bolt rod. As a result stresses arise which can cause shear fracture of the bolt.

  7. Weldability of High Alloys

    SciTech Connect

    Maroef, I

    2003-01-22

    The purpose of this study was to investigate the effect of silicon and iron on the weldability of HAYNES HR-160{reg_sign} alloy. HR-I60 alloy is a solid solution strengthened Ni-Co-Cr-Si alloy. The alloy is designed to resist corrosion in sulfidizing and other aggressive high temperature environments. Silicon is added ({approx}2.75%) to promote the formation of a protective oxide scale in environments with low oxygen activity. HR-160 alloy has found applications in waste incinerators, calciners, pulp and paper recovery boilers, coal gasification systems, and fluidized bed combustion systems. HR-160 alloy has been successfully used in a wide range of welded applications. However, the alloy can be susceptible to solidification cracking under conditions of severe restraint. A previous study by DuPont, et al. [1] showed that silicon promoted solidification cracking in the commercial alloy. In earlier work conducted at Haynes, and also from published work by DuPont et al., it was recognized that silicon segregates to the terminal liquid, creating low melting point liquid films on solidification grain boundaries. Solidification cracking has been encountered when using the alloy as a weld overlay on steel, and when joining HR-160 plate in a thickness greater than19 millimeters (0.75 inches) with matching filler metal. The effect of silicon on the weldability of HR-160 alloy has been well documented, but the effect of iron is not well understood. Prior experience at Haynes has indicated that iron may be detrimental to the solidification cracking resistance of the alloy. Iron does not segregate to the terminal solidification product in nickel-base alloys, as does silicon [2], but iron may have an indirect or interactive influence on weldability. A set of alloys covering a range of silicon and iron contents was prepared and characterized to better understand the welding metallurgy of HR-160 alloy.

  8. Transformation process for production of ultrahigh carbon steels and new alloys

    DOEpatents

    Strum, M.J.; Goldberg, A.; Sherby, O.D.; Landingham, R.L.

    1995-08-29

    Ultrahigh carbon steels with superplastic properties are produced by heating a steel containing ferrite and carbide phases to a soaking temperature approximately 50 C above the A{sub 1} transformation temperature, soaking the steel above the A{sub 1} temperature for a sufficient time that the major portion of the carbides dissolve into the austenite matrix, and then cooling the steel in a controlled manner within predetermined limits of cooling rate or transformation temperature, to obtain a steel having substantially spheroidal carbides. New alloy compositions contain aluminum and solute additions which promote the formation of a fine grain size and improve the resistance of the carbides to coarsening at the forming temperature. 9 figs.

  9. Transformation process for production of ultrahigh carbon steels and new alloys

    DOEpatents

    Strum, Michael J.; Goldberg, Alfred; Sherby, Oleg D.; Landingham, Richard L.

    1995-01-01

    Ultrahigh carbon steels with superplastic properties are produced by heating a steel containing ferrite and carbide phases to a soaking temperature approximately 50.degree. C. above the A.sub.1 transformation temperature, soaking the steel above the A.sub.1 temperature for a sufficient time that the major portion of the carbides dissolve into the austenite matrix, and then cooling the steel in a controlled manner within predetermined limits of cooling rate or transformation temperature, to obtain a steel having substantially spheroidal carbides. New alloy compositions contain aluminum and solute additions which promote the formation of a fine grain size and improve the resistance of the carbides to coarsening at the forming temperature.

  10. Identifying electronic properties relevant to improving stability in a-Si:H-based cells and overall performance in a-Si,Ge:H-based cells. Annual subcontract report, 18 April 1995--17 April 1996

    SciTech Connect

    Cohen, J.D.

    1997-03-01

    The work done during this second phase of the University of Oregon`s NREL subcontract focused on degradation studies in both pure a-Si:H and a-Si,Ge:H alloys, as well as a detailed study of the interface between these two materials in a-Si:H/a-Si, Ge:H heterostructures. All samples discussed in this report were produced by the glow-discharge method and were obtained either in collaboration with United Solar Systems Corporation or with researchers at Lawrence Berkeley laboratory. First, the results from the a-Si, Ge:H degradation studies support the conclusion that considerable quantities of charged defects exist in nominally intrinsic material. Researchers found that on light-soaking, all the observed defect sub-bands increased; however, their ratios varied significantly. Second, researchers performed voltage pulse stimulated capacitance transient measurements on a-Si:H/a-Si, Ge:H heterostructure samples and found a clear signature of trapped hole emission extending over long times. Finally, researchers began comparison studies of the electronic properties of a-Si:H grown by glow discharge either with 100% silane, or with silane diluted in H{sub 2} or He gas. The results on these samples indicate that the films grown under high hydrogen dilution exhibit roughly a factor of 3 lower deep defect densities than those grown using pure silane.

  11. Study of Magnetic Alloys: Critical Phenomena.

    DTIC Science & Technology

    MAGNETIC ALLOYS, TRANSPORT PROPERTIES), ELECTRICAL RESISTANCE, SEEBECK EFFECT , MAGNETIC PROPERTIES, ALUMINUM ALLOYS, COBALT ALLOYS, GADOLINIUM ALLOYS, GOLD ALLOYS, IRON ALLOYS, NICKEL ALLOYS, PALLADIUM ALLOYS, PLATINUM ALLOYS, RHODIUM ALLOYS

  12. Integral bypass diodes in an amorphous silicon alloy photovoltaic module

    NASA Technical Reports Server (NTRS)

    Hanak, J. J.; Flaisher, H.

    1991-01-01

    Thin-film, tandem-junction, amorphous silicon (a-Si) photovoltaic modules were constructed in which a part of the a-Si alloy cell material is used to form bypass protection diodes. This integral design circumvents the need for incorporating external, conventional diodes, thus simplifying the manufacturing process and reducing module weight.

  13. Microstructures and Mechanical Responses of Powder Metallurgy Noncombustive Magnesium Extruded Alloy by Rapid Solidification Process in Mass Production

    DTIC Science & Technology

    2010-05-01

    kg/m3, and its alloy is lightest of the industrial metals. It has a higher specific tensile strength than other metals, such as aluminum, iron, and...titanium alloys (1). Therefore, it promises to save energy and reduce air pollutants , such as CO2, SOx, and NOx, through weight reduction as...Oxidation Surface Film and Suppression of Ignition of Molten Mg-Ca Alloy by Ca Addition. J. Japan Foundry Engineering Society 1997, 69, 227–233. 18

  14. Fe-Zn Alloy Coating on Galvannealed (GA) Steel Sheet to Improve Product Qualities

    NASA Astrophysics Data System (ADS)

    Pradhan, Debabrata; Guin, Akshya Kumar; Raju, Pankaj; Manna, Manindra; Dutta, Monojit; Venugopalan, T.

    2014-09-01

    Galvannealed steel sheets (GA) have become the mainstream steel sheet for automobile applications because of their superior corrosion resistance, paintability, and weldability. To impart specific properties, different coatings on GA steel sheet were reported to improve properties further. In this context, we have developed an electroplating process (flash coating) for bright and adherent Fe-Zn alloy coating on GA steel sheet to enhance performances such as weldability, frictional behavior, phosphatability, and defect coverage. A comparative study with bare GA steel sheet was carried out for better elastration. The electroplating time was reduced below 10 s for practical applicability in an industrial coating line by modulating the bath composition. Electroplating was performed at current density of 200-500 A/m2 which yielded with higher cathode current efficiency of 85-95%. The performance results show that Fe-10 wt.% Zn-coated GA steel sheet (coating time 7 s) has better spot weldability, lower dynamic coefficient of friction (0.06-0.07 in lubrication), and better corrosion resistance compared to bare GA steel sheet. Uniform phosphate coating with globular crystal size of 2-5 µm was obtained on Fe-Zn flash-coated GA steel sheet. Hopeite was the main phosphate compound (77.9 wt.%) identified along with spencerite (13.6 wt.%) and phosphophyllite (8.5 wt.%).

  15. Production of aluminum-silicon alloy and ferrosilicon and commercial purity aluminum by the direct reduction process. First interim technical report, Phase D, January 1-March 31, 1981

    SciTech Connect

    Bruno, M.J.

    1981-04-01

    Operation of the bench AF-reactor on burden with all reducing carbon exterior to the ore pellet resulted in low metal alloy product yields and prematurely terminated runs, indicating the need for intimate contact between alumina and carbon to produce oxycarbide liquid prior to reaction with solid silicon carbide. Carbon solubility tests made on 60Al-40Si alloys at 2200/sup 0/C in graphite crucibles indicated continued reaction to form SiC for one hour. Efficiency of reduction to SiC ranged from 68 to 100%. The A-C two-electrode submerged arc reactor pilot, SAR-II, was successfully operated on both alumina-clay-coke and alumina-silicon carbide-coke (from the VSR prereduction) burdens. Metal alloy was produced and tapped in each of four runs. The pilot crystallizer was operated to evalute the two-stage (stop and go) crystallization technique on obtaining high yields of Al in Al-Si eutectic, with a limit of 1.0% Fe and 0.1% Ti in the alloy product. 18 figures, 19 tables. (DLC)

  16. Structural and interfacial properties of large area n-a-Si:H/i-a-Si:H/p-c-Si heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Pehlivan, Özlem; Menda, Deneb; Yilmaz, Okan; Kodolbaş, Alp Osman; Ödemir, Orhan; Duygulu, Özgur; Kutlu, Kubilay; Tomak, Mehmet

    2013-09-01

    Large area (72 cm2) doping inversed HIT solar cells (n-a-Si:H/i-a-Si:H/p-c-Si) were investigated by High Resolution Transmission Electron Microscopy (HR-TEM), Spectroscopic Ellipsometry (SE), Fourier Transform Infrared Attenuated Total Reflection spectroscopy (FTIR-ATR) and current-voltage (I-V) measurement. Mixture of microcrystalline and amorphous phase was identified via HR-TEM picture at the interface of i-a-Si:H/p-c-Si heterojunction. Using multilayer and Effective Medium Approximation (EMA) to the SE data, excellent fit was obtained, describing the evolution of microstructure of a-Si:H deposited at 225 °C on p-c-Si. Cody energy gap with combination of FTIR-ATR analyses were consistent with HRTEM and SE results in terms of mixture of microcrystalline and amorphous phase. Presence of such hetero-interface resulted poor open circuit voltage, Voc, of the fabricated solar cell devices, determined by I-V measurement under 1 sun. Moreover, Voc was also estimated from dark I-V analysis, revealing consistent Voc values. Efficiencies of fabricated cells over complete c-Si wafer (72 cm2) were calculated as 4.7 and 9.2 %. Improvement in efficiency was interpreted due to the back surface cleaning and selecting aluminum/silver alloy as front contact.

  17. Optimum doping level in a-Si:H and a-SiC:H materials

    NASA Astrophysics Data System (ADS)

    Hadjadj, A.; St'ahel, P.; Roca i Cabarrocas, P.; Paret, V.; Bounouh, Y.; Martin, J. C.

    1998-01-01

    The changes in the optical and electrical properties of thick a-Si:H and a-SiC:H films doped with diborane are investigated. In situ spectroscopic ellipsometry measurements reveal that, at a ratio of diborane to silane Cg=[B2H6]/[SiH4]<10-3, the optical properties of both materials are not strongly modified by boron doping. However, in the case of a-Si:H films, an improvement of the morphological and optical properties is observed at Cg=0.45×10-3. The existence of an optimum doping level at Cg<10-3 in the case of an a-Si:H p layer is confirmed by the dependence of the open-circuit voltage of a-Si:H based solar cells on the doping level of the p layer.

  18. Nano-Scale Fission Product Phases in an Irradiated U-7Mo Alloy Nuclear Fuel

    SciTech Connect

    Dennis Keiser, Jr.; Brandon Miller; James Madden; Jan-Fong Jue; Jian Gan

    2014-09-01

    Irradiated nuclear fuel is a very difficult material to characterize. Due to the large radiation fields associated with these materials, they are hard to handle and typically have to be contained in large hot cells. Even the equipment used for performing characterization is housed in hot cells or shielded glove boxes. The result is not only a limitation in the techniques that can be employed for characterization, but also a limitation in the size of features that can be resolved The most standard characterization techniques include light optical metallography (WM), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). These techniques are applied to samples that are typically prepared using grinding and polishing approaches that will always generate some mechanical damage on the sample surface. As a result, when performing SEM analysis, for example, the analysis is limited by the quality of the sample surface that can be prepared. However, a new approach for characterizing irradiated nuclear fuel has recently been developed at the Idaho National Laboratory (INL) in Idaho Falls, Idaho. It allows for a dramatic improvement in the quality of characterization that can be performed when using an instrument like an SEM. This new approach uses a dual-beam scanning microscope, where one of the beams isa focused ion beam (FIB), which can be used to generate specimens of irradiated fuel (-10µm x 10µm) for microstructural characterization, and the other beam is the electron beam of an SEM. One significant benefit of this approach is that the specimen surface being characterized has received much less damage (and smearing) than is caused by the more traditional approaches, which enables the imaging of nanometer­ sized microstructural features in the SEM. The process details are for an irradiated low-enriched uranium (LEU) U-Mo alloy fuel Another type of irradiated fuel that has been characterized using this technique is a mixed oxide fuel.

  19. Palladium alloys for biomedical devices.

    PubMed

    Wataha, John C; Shor, Kavita

    2010-07-01

    In the biomedical field, palladium has primarily been used as a component of alloys for dental prostheses. However, recent research has shown the utility of palladium alloys for devices such as vascular stents that do not distort magnetic resonance images. Dental palladium alloys may contain minor or major percentages of palladium. As a minor constituent, palladium hardens, strengthens and increases the melting range of alloys. Alloys that contain palladium as the major component also contain copper, gallium and sometimes tin to produce strong alloys with high stiffness and relatively low corrosion rates. All current evidence suggests that palladium alloys are safe, despite fears about harmful effects of low-level corrosion products during biomedical use. Recent evidence suggests that palladium poses fewer biological risks than other elements, such as nickel or silver. Hypersensitivity to palladium alone is rare, but accompanies nickel hypersensitivity 90-100% of the time. The unstable price of palladium continues to influence the use of palladium alloys in biomedicine.

  20. Alloy Selection System

    SciTech Connect

    2001-02-01

    Software will Predict Corrosion Rates to Improve Productivity in the Chemical Industry. Many aspects of equipment design and operation are influenced by the choice of the alloys used to fabricate process equipment.

  1. Reducing metal alloy powder costs for use in powder bed fusion additive manufacturing: Improving the economics for production

    NASA Astrophysics Data System (ADS)

    Medina, Fransisco

    Titanium and its associated alloys have been used in industry for over 50 years and have become more popular in the recent decades. Titanium has been most successful in areas where the high strength to weight ratio provides an advantage over aluminum and steels. Other advantages of titanium include biocompatibility and corrosion resistance. Electron Beam Melting (EBM) is an additive manufacturing (AM) technology that has been successfully applied in the manufacturing of titanium components for the aerospace and medical industry with equivalent or better mechanical properties as parts fabricated via more traditional casting and machining methods. As the demand for titanium powder continues to increase, the price also increases. Titanium spheroidized powder from different vendors has a price range from 260/kg-450/kg, other spheroidized alloys such as Niobium can cost as high as $1,200/kg. Alternative titanium powders produced from methods such as the Titanium Hydride-Dehydride (HDH) process and the Armstrong Commercially Pure Titanium (CPTi) process can be fabricated at a fraction of the cost of powders fabricated via gas atomization. The alternative powders can be spheroidized and blended. Current sectors in additive manufacturing such as the medical industry are concerned that there will not be enough spherical powder for production and are seeking other powder options. It is believed the EBM technology can use a blend of spherical and angular powder to build fully dense parts with equal mechanical properties to those produced using traditional powders. Some of the challenges with angular and irregular powders are overcoming the poor flow characteristics and the attainment of the same or better packing densities as spherical powders. The goal of this research is to demonstrate the feasibility of utilizing alternative and lower cost powders in the EBM process. As a result, reducing the cost of the raw material to reduce the overall cost of the product produced with

  2. Alloy materials

    DOEpatents

    Hans Thieme, Cornelis Leo; Thompson, Elliott D.; Fritzemeier, Leslie G.; Cameron, Robert D.; Siegal, Edward J.

    2002-01-01

    An alloy that contains at least two metals and can be used as a substrate for a superconductor is disclosed. The alloy can contain an oxide former. The alloy can have a biaxial or cube texture. The substrate can be used in a multilayer superconductor, which can further include one or more buffer layers disposed between the substrate and the superconductor material. The alloys can be made a by process that involves first rolling the alloy then annealing the alloy. A relatively large volume percentage of the alloy can be formed of grains having a biaxial or cube texture.

  3. Oxidation products of Inconel alloys 600 and 690 in hydrogenated steam environments and their role in stress corrosion cracking

    NASA Astrophysics Data System (ADS)

    Ferguson, J. Bryce

    Inconel Alloys 600 and 690 are used extensively in components of Nuclear Pressurized Water Reactors (PWR) in the primary water loop which consists of H2 supersaturated steam. Alloy 600 has been found to crack intergranularly when exposed to primary water conditions. Alloy 690 was designed as a replacement and is generally regarded as immune to cracking. There is no consensus as to the mechanism which is responsible for cracking or the lack thereof in these alloys. In this work thermodynamic arguments for the stability of Ni and Cr compounds developed under pressurized water reactor environments ( PH2O and PH2 ) were experimentally tested. A mechanism is proposed to explain crack initiation and propagation alloy 600 along the grain boundaries where Cr2O3 has formed from the leaching of Cr from the matrix leaving behind a porous Ni-rich region. The mechanism is based on the thermodynamic potential for the transformation of a protective NiO surface layer into an amorphous non-protective Ni(OH)2 gel. This gel would also form along the grain boundaries and when hydrogenated steam reaches the porous Ni-rich regions. Crack initiation is then favored by tensile stressing of the grain boundary regions which can easily rupture the gelatinous film. The leaching of matrix Cr to form non-protective CrOOH gel at the crack tip followed by the exposure of fresh porous Ni to the environment also explains crack propagation in inconel alloy 600. The proposed crack initiation mechanism is not expected to occur in alloy 690 where a protective Cr2O 3 film covers the entire metal surface. However, crack propagation along the grain boundaries in alloy 600 and pre-cracked alloy 690 is expected to be active as hydroxide-forming reactions weaken the material at the grain boundaries.

  4. Grinding as an approach to the production of high-strength, dispersion-strengthened nickel-base alloys

    NASA Technical Reports Server (NTRS)

    Orth, N. W.; Quatinetz, M.; Weeton, J. W.

    1970-01-01

    Mechanical process produces dispersion-strengthened metal alloys. Power surface contamination during milling is removed by a cleaning method that involves heating thin shapes or partially-compacted milled powder blends in hydrogen to carefully controlled temperature schedules.

  5. Alloy composition effects on oxidation products of VIA, B-1900, 713C, and 738X: A high temperature diffractometer study

    NASA Technical Reports Server (NTRS)

    Garlick, R. G.; Lowell, C.

    1973-01-01

    High temperature X-ray diffraction studies were performed to investigate isothermal and cyclic oxidation at 1000 and 1100 C of the nickel-base superalloys VIA, B-1900, 713C, and 738X. Oxidation was complex. The major oxides, Al2O3, Cr2O3, and the spinels, formed in amounts consistent with alloy chemistry. The alloys VIA and B-1900 (high Al, low Cr alloys) tended to form Al2O3 and NiAl2O4; 738X (high Cr, low Al) formed Cr2O3 and NiCr2O4. A NiTa2O6 type of oxide formed in amounts approximately proportional to the refractory metal content of the alloy. One of the effects of cycling was to increase the amount of spinels formed.

  6. Method for the production of strongly adhesive films on titanium and titanium alloys with a metallization process

    NASA Technical Reports Server (NTRS)

    Hahn, H. J.

    1986-01-01

    A process for the spray-application of a strongly adhesive, thick antifriction layer on titanium and titanium alloys is proposed. The titanium/titanium alloy component to be coated is first subjected to cleaning in a pickling bath with reducing additives and sand-blasting, then coated with an intermediate layer of nickel, after which the final layer is applied. The formation of TiNi at the interface ensures strong bonding of the antifriction layer.

  7. A New Method for Low Cost Production of Titanium Alloys for Reducing Energy Consumption of Mechanical Systems

    SciTech Connect

    Fang, Z. Zak; Chandran, Ravi; Koopman, Mark

    2016-02-29

    This project investigated an innovative manufacturing process intended to minimize the cost of production of titanium materials and components, and increase the adoption of Ti components for energy consuming applications, such as automobiles. A key innovation of the proposed manufacturing approach is a novel Ti powder sintering technology for making titanium materials with ultrafine grain microstructure in the as-sintered state with minimum, or an absence, of post-sintering processes. The new sintering technology is termed Hydrogen Sintering and Phase Transformations (HSPT), and constitutes a promising manufacturing technology that can be used to produce titanium (Ti) materials and components in a near-net-shape form, thus also minimizing machining costs. Our objective was to meet, or possibly surpass, the mechanical property levels for ASTM B348 Grade 5 for wrought Ti-6Al-4V. Although specific applications call for varying mechanical property requirements, ASTM B348 was created for the demanding applications of the aerospace industry, and is the established standard for Ti-6Al-4V. While the primary goal was to meet, or exceed this standard, the team also had the goal of demonstrating this could be done at a significantly lower cost of production. Interim goals of the project were to fully develop this novel sintering process, and provide sufficient baseline testing to make the method practical and attractive to industry. By optimizing the process parameters for the sintering of titanium hydride (TiH2) powders in a hydrogen atmosphere and controlling the phase transformations during and after sintering, the HSPT process was expected to reduce the energy consumption, and thus cost, of making Ti alloys and fabricating Ti components. The process was designed such that no high temperature melting is required for producing Ti alloys; little or no post-sintering processing is needed for producing desired microstructures (and therefore enhanced mechanical

  8. Production of hydroxyapatite layers on the plasma electrolytically oxidized surface of titanium alloys.

    PubMed

    Lugovskoy, Alex; Lugovskoy, Svetlana

    2014-10-01

    Hydroxyapatite (HA) is a bioactive material that is widely used for improving the osseointegration of titanium dental implants. Titanium can be coated with HA by various methods, such as chemical vapor deposition (CVD), thermal spray, or plasma spray. HA coatings can also be grown on titanium surfaces by hydrothermal, chemical, and electrochemical methods. Plasma electrolytic oxidation (PEO), or microarc oxidation (MAO), is an electrochemical method that enables the production of a thick porous oxide layer on the surface of a titanium implant. If the electrolyte in which PEO is performed contains calcium and phosphate ions, the oxide layer produced may contain hydroxyapatite. The HA content can then be increased by subsequent hydrothermal treatment. The HA thus produced on titanium surfaces has attractive properties, such as a high porosity, a controllable thickness, and a considerable density, which favor its use in dental and bone surgery. This review summarizes the state of the art and possible further development of PEO for the production of HA on Ti implants.

  9. Relationship between various deformation-induced products and mechanical properties in metastable Ti-30Zr-Mo alloys for biomedical applications.

    PubMed

    Zhao, Xiaoli; Niinomi, Mitsuo; Nakai, Masaaki

    2011-11-01

    Nowadays, there is a significant research focus on the development of bio-implant materials that have not only a low Young's modulus but also other unique characteristics such as a changeable Young's modulus and the ability to prevent calcium phosphate formation. Taking advantage of deformation-induced phases is an effective way to obtain the changeable Young's modulus. This study investigated the relationship between the various deformation-induced products and the mechanical properties-including Young's modulus, microstructure, and tensile properties-of Ti-30Zr-(5,6,7)mass%Mo alloys subjected to solution treatment (ST) and cold-rolling (CR). After ST, each alloy is composed of a β phase and a small amount of athermally formed ω phase, and exhibits a low Young's modulus. During CR, deformation-induced phase transformation occurs in all the alloys. The change in Young's modulus due to CR is highly dependent on the types of deformation-induced products. The decrease in Young's modulus due to CR is related to the deformation-induced α' phase transformation accompanying with the disappearance of athermal ω phase, and the increase in Young's modulus is attributed to the deformation-induced ω phase, which mainly exists in {332}β mechanical twins. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. The structure of a-Si 1-xSn x:H thin films

    NASA Astrophysics Data System (ADS)

    Edwards, A. M.; Fairbanks, M. C.; Newport, R. J.

    1990-12-01

    The doping of a-Si:H with Sn is known to modify the electrical and optical properties of the material. The optical band gap decreases as the doping level is increased, however, there is no insulator-metal transition of the type observed, for example, when transition metals are used as dopants. In order to increase the understanding of the conductivity processes that occur in a-Si:metal:H alloys we have measured the atomic scale structure of a series of a-Si 1- xSn x:H thin-films using EXAFS. Samples were prepared by RF reactive co-sputtering and both Si and Sn K-edge EXAFS examined. The results indicate that the Sn atoms are substituted randomly into the a-Si tetrahedral random network. Both Si and Sn atoms retain fourfold co-ordination over the composition range studied (0⩽ x⩽0.18). In contrast to results obtained using transition metal dopants there is no local modification of the tetrahedral random network.

  11. Correlation of the energy product with evolution of the nanostructure in Y,Dy,Nd-(Fe,Co)-B magnetic alloy

    SciTech Connect

    Wu, Y.Q; Tang, W.; Kramer, M.J.; Dennis, K.W.; Oster, N.; McCallum, R.W.; Anderson, I.E.

    2009-07-24

    The devitrification behavior of nanocrystalline MRE{sub 2}(Fe,Co){sub 14}B+ZrC (MRE = Nd+Y+Dy) was studied using differential scanning calorimetry (DSC), synchrotron high temperature x-ray diffraction, and analytical transmission electron microscopy (TEM) techniques. Alloy ribbons were melt spun at 25 m/s to obtain an amorphous structure. Optimum hard magnetic properties (B{sub r} = 7.2 kG, H{sub c} = 12.7 kOe and (BH){sub max} = 10.8 MG Oe) were obtained in ribbons annealed at 750 C for 15 min. A reduced annealing temperature of 638 C and holding time from 0 to 11 min were chosen based on DSC analysis. Large changes in both microstructure and hard magnetic properties were found in a narrow window of annealing time, 4.5-6 min, resulting in a dramatic increase in energy product, remanence and coercivity: 0.96 MG Oe, 5.2 kG, 2.7 kOe to 5.7 MG Oe, 7.2 kG, 8.5 kOe for (BH){sub max}, B{sub r} and H{sub c}, respectively. Energy dispersive x-ray spectroscopy and energy filtered TEM analyses indicate that Zr- and C-rich particles ({approx} 5 nm) and thin grain boundary layers (1-2 nm thick) are formed surrounding 2-14-1 hard phase grains when the annealing time is over 6 min. Further annealing resulted in a more distinct hard phase surrounded by a nonmagnetic grain boundary phase {approx} 1 nm in thickness. The thin grain boundary layer phase starts to disappear with annealing time over 11 min. The partitioning behavior of various elements at different annealing conditions appears to be associated with significant changes in magnetic properties, leading to an improved optimum microstructure.

  12. Manganese concentrations in the soil and air in the vicinity of a closed manganese alloy production plant.

    PubMed

    Boudissa, Soraya M; Lambert, Jean; Müller, Caroline; Kennedy, Greg; Gareau, Lise; Zayed, Joseph

    2006-05-15

    In Montreal (Canada), the mean annual atmospheric Mn concentrations between 1981 and 1990 were stable, followed by a decrease of almost 50% from 1990 to 1992. The reason for such a decrease in Mn is probably the shutdown of a large manganese alloy production plant in Beauharnois, approximately 25 km from Montreal. The objective of this study is to assess the level of air and soil contamination by Mn in the vicinity of this ferroalloy plant more than 10 years after its closure. Air and soil were sampled over 5 days at two and three sites, respectively. Site 1 was located 10 m NE of the closed plant, in the direction of the prevailing SW-NE winds. Sites 2 and 3 were at 50 and 800 m SE from the plant. Air samples were collected in order to determine total (MnT) and respirable (MnR). Soil samples were taken in the surface and subsurface strata. The results show that site 1 is extremely polluted with a mean Mn concentration in surface strata of 2,66,000+/-45,000 ppm and 2,83,000+/-23,000 ppm in the subsurface strata, while the average MnT and MnR are 21.9+/-13.7 and 3.5+/-3.9 microg/m(3), respectively. The explanation for this contamination is direct deposition on the soil of solid Mn-rich residue and atmospheric erosion of Mn particles. The situation should be remediated by the public authority with high priority.

  13. Comparative life-cycle energy payback analysis of multi-junction a-SiGe and nanocrystalline/a-Si modules

    SciTech Connect

    Fthenakis, V.; Kim, H.

    2010-07-15

    Despite the publicity of nanotechnologies in high tech industries including the photovoltaic sector, their life-cycle energy use and related environmental impacts are understood only to a limited degree as their production is mostly immature. We investigated the life-cycle energy implications of amorphous silicon (a-Si) PV designs using a nanocrystalline silicon (nc-Si) bottom layer in the context of a comparative, prospective life-cycle analysis framework. Three R and D options using nc-Si bottom layer were evaluated and compared to the current triple-junction a-Si design, i.e., a-Si/a-SiGe/a-SiGe. The life-cycle energy demand to deposit nc-Si was estimated from parametric analyses of film thickness, deposition rate, precursor gas usage, and power for generating gas plasma. We found that extended deposition time and increased gas usages associated to the relatively high thickness of nc-Si lead to a larger primary energy demand for the nc-Si bottom layer designs, than the current triple-junction a-Si. Assuming an 8% conversion efficiency, the energy payback time of those R and D designs will be 0.7-0.9 years, close to that of currently commercial triple-junction a-Si design, 0.8 years. Future scenario analyses show that if nc-Si film is deposited at a higher rate (i.e., 2-3 nm/s), and at the same time the conversion efficiency reaches 10%, the energy-payback time could drop by 30%.

  14. Utilization of amorphous silicon carbide (a-Si:C:H) as a resistive layer in gas microstrip detectors

    SciTech Connect

    Hong, W.S.; Cho, H.S.; Perez-Mendez, V.; Gong, W.G.

    1995-04-01

    Thin semiconducting films of hydrogenated amorphous silicon (a-Si:H) and its carbon alloy (a-Si:C:H) were applied to gas microstrip detectors in order to control gain instabilities due to charges on the substrate. Thin ({approximately}100nm) layers of a-Si:H or p-doped a-Si:C:H were placed either over or under the electrodes using the plasma enhanced chemical vapor deposition (PECVD) technique to provide the substrate with a suitable surface conductivity. By changing the carbon content and boron doping density, the sheet resistance of the a-Si:C:H coating could be successfully controlled in the range of 10{sup 12} {approximately} 10{sup 17} {Omega}/{four_gradient}, and the light sensitivity, which causes the resistivity to vary with ambient light conditions, was minimized. An avalanche gain of 5000 and energy resolution of 20% FWHM were achieved and the gain remained constant over a week of operation. A-Si:C:H film is an attractive alternative to ion-implanted or semiconducting glass due to the wide range of resistivities possible and the feasibility of making deposits over a large area at low cost.

  15. Improvement of parameters in a-Si(p)/c-Si(n)/a-Si(n) solar cells

    NASA Astrophysics Data System (ADS)

    Moustafa Bouzaki, Mohammed; Aillerie, Michel; Ould Saad Hamady, Sidi; Chadel, Meriem; Benyoucef, Boumediene

    2016-10-01

    We analyzed and discussed the influence of thickness and doping concentration of the different layers in a-Si(p)/c-Si(n)/a-Si(n) photovoltaic (PV) cells with the aim of increasing its efficiency while decreasing its global cost. Compared to the efficiency of a standard marketed PV cell, elaborated with a ZnO transparent conductive oxide (TCO) layer but without Back Surface Field (BSF) layer, an optimization of the thickness and dopant concentration of both the emitter a-Si(p) and absorber c-Si(n) layers will gain about 3% in the global efficiency of the cell. The results also reveal that with introduction of the third layer, i.e. the BSF layer, the efficiency always achieves values above 20% and all other parameters of the cell, such as the open-circuit voltage, the short-circuit current and the fill-factor, are strongly affected by the thickness and dopant concentration of the layers. The values of all parameters are given and discussed in the paper. Thereby, the simulation results give for an optimized a-Si(p)/c-Si(n)/a-Si(n) PV cells the possibility to decrease the thickness of the absorber layer down to 50 μm which is lower than in the state-of-the-art. This structure of the cell achieves suitable properties for high efficiency, cost-effectiveness and reliable heterojunction (HJ) solar cell applications.

  16. Production and Precipitation Hardening of Beta-Type Ti-35Nb-10Cu Alloy Foam for Implant Applications

    NASA Astrophysics Data System (ADS)

    Mutlu, Ilven; Yeniyol, Sinem; Oktay, Enver

    2016-04-01

    In this study, beta-type Ti-35Nb-10Cu alloy foams were produced by powder metallurgy method for dental implant applications. 35% Nb was added to stabilize the beta-Ti phase with low Young's modulus. Cu addition enhanced sinterability and gave precipitation hardening capacity to the alloy. Sintered specimens were precipitation hardened in order to enhance the mechanical properties. Electrochemical corrosion behavior of the specimens was examined by electrochemical impedance spectroscopy in artificial saliva. Electrochemical impedance spectroscopy results indicated that the oxide film on the surface of foam is a bi-layer structure consisting of outer porous layer and inner barrier layer. Impedance values of barrier layer were higher than porous layer. Corrosion resistance of specimens decreased at high fluoride concentrations and at low pH of artificial saliva. Corrosion resistance of alloys was slightly decreased with aging. Mechanical properties, microstructure, and surface roughness of the specimens were also examined.

  17. Stimulatory effects of the degradation products from Mg-Ca-Sr alloy on the osteogenesis through regulating ERK signaling pathway

    PubMed Central

    Li, Mei; He, Peng; Wu, Yuanhao; Zhang, Yu; Xia, Hong; Zheng, Yufeng; Han, Yong

    2016-01-01

    The influence of Mg-1Ca-xwt.% Sr (x = 0.2, 0.5, 1.0, 2.0) alloys on the osteogenic differentiation and mineralization of pre-osteoblast MC3T3-E1 were studied through typical differentiation markers, such as intracellular alkaline phosphatase (ALP) activity, extracellular collagen secretion and calcium nodule formation. It was shown that Mg-1Ca alloys with different content of Sr promoted cell viability and enhanced the differentiation and mineralization levels of osteoblasts, and Mg-1Ca-2.0Sr alloy had the most remarkable and significant effect among all. To further investigate the underlying mechanisms, RT-PCR and Western Blotting assays were taken to analyze the mRNA expression level of osteogenesis-related genes and intracellular signaling pathways involved in osteogenesis, respectively. RT-PCR results showed that Mg-1Ca-2.0Sr alloy significantly up-regulated the expressions of the transcription factors of Runt-related transcription factor 2 (RUNX2) and Osterix (OSX), Integrin subunits, as well as alkaline phosphatase (ALP), Bone sialoprotein (BSP), Collagen I (COL I), Osteocalcin (OCN) and Osteopontin (OPN). Western Blotting results suggested that Mg-1Ca-2.0Sr alloy rapidly induced extracellular signal-regulated kinase (ERK) activation but showed no obvious effects on c-Jun N terminal kinase (JNK) and p38 kinase of MAPK. Taken together, our results demonstrated that Mg-1Ca-2.0Sr alloy had excellent biocompatibility and osteogenesis via the ERK pathway and is expected to be promising as orthopedic implants and bone repair materials. PMID:27580744

  18. Stimulatory effects of the degradation products from Mg-Ca-Sr alloy on the osteogenesis through regulating ERK signaling pathway

    NASA Astrophysics Data System (ADS)

    Li, Mei; He, Peng; Wu, Yuanhao; Zhang, Yu; Xia, Hong; Zheng, Yufeng; Han, Yong

    2016-09-01

    The influence of Mg-1Ca-xwt.% Sr (x = 0.2, 0.5, 1.0, 2.0) alloys on the osteogenic differentiation and mineralization of pre-osteoblast MC3T3-E1 were studied through typical differentiation markers, such as intracellular alkaline phosphatase (ALP) activity, extracellular collagen secretion and calcium nodule formation. It was shown that Mg-1Ca alloys with different content of Sr promoted cell viability and enhanced the differentiation and mineralization levels of osteoblasts, and Mg-1Ca-2.0Sr alloy had the most remarkable and significant effect among all. To further investigate the underlying mechanisms, RT-PCR and Western Blotting assays were taken to analyze the mRNA expression level of osteogenesis-related genes and intracellular signaling pathways involved in osteogenesis, respectively. RT-PCR results showed that Mg-1Ca-2.0Sr alloy significantly up-regulated the expressions of the transcription factors of Runt-related transcription factor 2 (RUNX2) and Osterix (OSX), Integrin subunits, as well as alkaline phosphatase (ALP), Bone sialoprotein (BSP), Collagen I (COL I), Osteocalcin (OCN) and Osteopontin (OPN). Western Blotting results suggested that Mg-1Ca-2.0Sr alloy rapidly induced extracellular signal-regulated kinase (ERK) activation but showed no obvious effects on c-Jun N terminal kinase (JNK) and p38 kinase of MAPK. Taken together, our results demonstrated that Mg-1Ca-2.0Sr alloy had excellent biocompatibility and osteogenesis via the ERK pathway and is expected to be promising as orthopedic implants and bone repair materials.

  19. Simultaneous Recovery of Iron and Phosphorus from a High-Phosphorus Oolitic Iron Ore to Prepare Fe-P Alloy for High-Phosphorus Steel Production

    NASA Astrophysics Data System (ADS)

    Yang, Congcong; Zhu, Deqing; Pan, Jian; Lu, Liming

    2017-09-01

    Unlike previous dephosphorization studies, the present work complies with a concept to recover phosphorus within the utilization of high-phosphorus oolitic iron ores to prepare Fe -P alloy for high-phosphorus steel production. Simultaneous enrichment of iron and phosphorus can be achieved by directly alloying the high-phosphorus oolitic iron ore at high reduction temperatures (≥1623 K). Neither fluxes nor other special additives need to be used. Consequently, the phosphorus element migrates from original apatite to the slag phase with the elevating temperature from 1323 K to 1473 K, and it further moves into metallic iron and forms Fe3P at 1623 K. A metalized iron -phosphorus alloy with assaying of 96.51% iron and 2.03% phosphorus content was obtained at 1623 K for 10 min at corresponding iron and phosphorus recovery rates of 97.50% and 64.51%, respectively. This process exhibits high economic efficiency and is practicable as a stepping-stone for the efficient and direct utilization of high-phosphorus iron ore resources.

  20. High efficiency thin film CdTe and a-Si based solar cells

    SciTech Connect

    Compaan, A. D.; Deng, X.; Bohn, R. G.

    2000-01-04

    This report describes work done by the University of Toledo during the first year of this subcontract. During this time, the CdTe group constructed a second dual magnetron sputter deposition facility; optimized reactive sputtering for ZnTe:N films to achieve 10 ohm-cm resistivity and {approximately}9% efficiency cells with a copper-free ZnTe:N/Ni contact; identified Cu-related photoluminescence features and studied their correlation with cell performance including their dependence on temperature and E-fields; studied band-tail absorption in CdS{sub x}Te{sub 1{minus}x} films at 10 K and 300 K; collaborated with the National CdTe PV Team on (1) studies of high-resistivity tin oxide (HRT) layers from ITN Energy Systems, (2) fabrication of cells on the HRT layers with 0, 300, and 800-nm CdS, and (3) preparation of ZnTe:N-based contacts on First Solar materials for stress testing; and collaborated with Brooklyn College for ellipsometry studies of CdS{sub x}Te{sub 1{minus}x} alloy films, and with the University of Buffalo/Brookhaven NSLS for synchrotron X-ray fluorescence studies of interdiffusion in CdS/CdTe bilayers. The a-Si group established a baseline for fabricating a-Si-based solar cells with single, tandem, and triple-junction structures; fabricated a-Si/a-SiGe/a-SiGe triple-junction solar cells with an initial efficiency of 9.7% during the second quarter, and 10.6% during the fourth quarter (after 1166 hours of light-soaking under 1-sun light intensity at 50 C, the 10.6% solar cells stabilized at about 9%); fabricated wide-bandgap a-Si top cells, the highest Voc achieved for the single-junction top cell was 1.02 V, and top cells with high FF (up to 74%) were fabricated routinely; fabricated high-quality narrow-bandgap a-SiGe solar cells with 8.3% efficiency; found that bandgap-graded buffer layers improve the performance (Voc and FF) of the narrow-bandgap a-SiGe bottom cells; and found that a small amount of oxygen partial pressure ({approximately}2 {times} 10

  1. Electrospun a-Si using Liquid Silane/Polymer Inks

    SciTech Connect

    D.L. Schulz; J.M. Hoey; J. Smith; J. Lovaasen; C. Braun; X. Dai; K. Anderson; A. Elangovan; X. Wu; S. Payne; K. Pokhodnya; I. Akhatov; L. Pederson; P. Boudjouk

    2010-12-01

    Amorphous silicon nanowires (a-SiNWs) were prepared by electrospinning cyclohexasilane (Si{sub 6}H{sub 12}) admixed with polymethylmethacrylate (PMMA) in toluene. Raman spectroscopy characterization of these wires (d {approx} 50-2000 nm) shows 350 C treatment yields a-SiNWs. Porous a-SiNWs are obtained using a volatile polymer.

  2. Electrospun a-Si using Liquid Silane/Polymer Inks

    SciTech Connect

    Doug Schulz

    2010-12-09

    Amorphous silicon nanowires (a-SiNWs) were prepared by electrospinning cyclohexasilane (Si{sub 6}H{sub 12}) admixed with polymethylmethacrylate (PMMA) in toluene. Raman spectroscopy characterization of these wires (d {approx} 50-2000 nm) shows 350 C treatment yields a-SiNWs. Porous a-SiNWs are obtained using a volatile polymer.

  3. Casting alloys.

    PubMed

    Wataha, John C; Messer, Regina L

    2004-04-01

    Although the role of dental casting alloys has changed in recent years with the development of improved all-ceramic materials and resin-based composites, alloys will likely continue to be critical assets in the treatment of missing and severely damaged teeth. Alloy shave physical, chemical, and biologic properties that exceed other classes of materials. The selection of the appropriate dental casting alloy is paramount to the long-term success of dental prostheses,and the selection process has become complex with the development of many new alloys. However, this selection process is manageable if the practitioner focuses on the appropriate physical and biologic properties, such as tensile strength, modulus of elasticity,corrosion, and biocompatibility, and avoids dwelling on the less important properties of alloy color and short-term cost. The appropriate selection of an alloy helps to ensure a longer-lasting restoration and better oral health for the patient.

  4. Molybdenum carbide supported nickel-molybdenum alloys for synthesis gas production via partial oxidation of surrogate biodiesel

    NASA Astrophysics Data System (ADS)

    Shah, Shreya; Marin-Flores, Oscar G.; Norton, M. Grant; Ha, Su

    2015-10-01

    In this study, NiMo alloys supported on Mo2C are synthesized by wet impregnation for partial oxidation of methyl oleate, a surrogate biodiesel, to produce syngas. When compared to single phase Mo2C, the H2 yield increases from 70% up to >95% at the carbon conversion of ∼100% for NiMo alloy nanoparticles that are dispersed over the Mo2C surface. Supported NiMo alloy samples are prepared at two different calcination temperatures in order to determine its effect on particle dispersion, crystalline phase and catalytic properties. The reforming test data indicate that catalyst prepared at lower calcination temperature shows better nanoparticle dispersion over the Mo2C surface, which leads to higher initial performance when compared to catalysts synthesized at higher calcination temperature. Activity tests using the supported NiMo alloy on Mo2C that are calcined at the lower temperature of 400 °C shows 100% carbon conversion with 90% H2 yield without deactivation due to coking over 24 h time-on-stream.

  5. High levels of hair manganese in children living in the vicinity of a ferro-manganese alloy production plant.

    PubMed

    Menezes-Filho, José A; Paes, Ciro R; Pontes, Angela M de C; Moreira, Josino C; Sarcinelli, Paula N; Mergler, Donna

    2009-11-01

    Manganese (Mn) is an essential element, but an effective toxic at high concentrations. While there is an extensive literature on occupational exposure, few studies have examined adults and children living near important sources of airborne Mn. The objective of this study was to analyze hair Mn of children living in the vicinity of a ferro-manganese alloy production plant in the Great Salvador region, State of Bahia, Brazil and examine factors that influence this bioindicator of exposure. We examined 109 children in the age range of 1-10 years, living near the plant. Four separate housing areas were identified a priori on the bases of proximity to the emission sources and downwind location. A non-exposed group (n=43) of similar socio-economic status was also evaluated. Mn hair (MnH) concentration was measured by graphite atomic absorption spectrometry (GFAAS). Possible confounding hematological parameters were also assessed. Mean MnH concentration was 15.20 microg/g (1.10-95.50 microg/g) for the exposed children and 1.37 microg/g (0.39-5.58 microg/g) for the non-exposed. For the former, MnH concentrations were 7.95+/-1.40 microg/g (farthest from the plant), 11.81+/-1.11 microg/g (mid-region), 34.43+/-8.66 microg/g (closest to the plant) and 34.22+/-9.15 microg/g (directly downwind). Multiple regression analysis on log transformed MnH concentrations for the exposed children derived a model that explained 36.8% of the variability. In order of importance, area of children's residence, gender (girls>boys) and time of mother's residence in the area at the birth of the child, were significantly associated with MnH. Post hoc analyses indicated two groupings for exposure areas, with those living closest to and downwind of the plant displaying higher MnH concentrations compared to the others. The contribution of the time the mother lived in the community prior to the child's birth to the children's current MnH suggests that in utero exposure may play a role. A study of

  6. Airborne manganese as dust vs. fume determining blood levels in workers at a manganese alloy production plant

    PubMed Central

    Park, Robert M.; Baldwin, Mary; Bouchard, Maryse F.; Mergler, Donna

    2015-01-01

    The appropriate exposure metrics for characterizing manganese (Mn) exposure associated with neurobehavioral effects have not been established. Blood levels of Mn (B-Mn) provide a potentially important intermediate marker of Mn airborne exposures. Using data from a study of a population of silicon- and ferro-manganese alloy production workers employed between 1973 and 1991, B-Mn levels were modeled in relation to prior Mn exposure using detailed work histories and estimated respirable Mn concentrations from air-sampling records. Despite wide variation in exposure levels estimated for individual jobs, duration of employment (exposure) was itself a strong predictor of B-Mn levels and strongest when an 80-day half-life was applied to contributions over time (t = 6.95, 7.44, respectively; p < 10 −5). Partitioning exposure concentrations based on process origin into two categories: (1) “large” respirable particulate (Mn-LRP) derived mainly from mechanically generated dust, and (2) “small” respirable particulate (Mn-SRP) primarily electric furnace condensation fume, revealed that B-Mn levels largely track the small, fume exposures. With a half-life of 65 days applied in a model with cumulative exposure terms for both Mn-LRP (t = −0.16, p = 0.87) and Mn-SRP (t = 6.45, p < 10 −5), the contribution of the large-size fraction contribution was negligible. Constructing metrics based on the square root of SRP exposure concentrations produced a better model fit (t = 7.87 vs. 7.44, R2 = 0.2333 vs. 0.2157). In a model containing both duration (t = 0.79, p = 0.43) and (square root) fume (t = 2.47, p = 0.01) metrics, the duration term was a weak contributor. Furnace-derived, small respirable Mn particulate appears to be the primary contributor to B-Mn levels, with a dose-rate dependence in a population chronically exposed to Mn, with air-concentrations declining in recent years. These observations may reflect the presence of homeostatic control of Mn levels in the blood

  7. HIGH LEVELS OF HAIR MANGANESE IN CHILDREN LIVING IN THE VICINITY OF A FERRO-MANGANESE ALLOY PRODUCTION PLANT

    PubMed Central

    Menezes-Filho, José A.; Paes, Ciro R.; de C. Pontes, Ângela M.; Moreira, Josino C.; Sarcinelli, Paula N.; Mergler, Donna

    2009-01-01

    Manganese (Mn) is an essential element, but an effective toxic at high concentrations. While there is an extensive literature on occupational exposure, few studies have examined adults and children living near important sources of airborne Mn. The objective of this study was to analyze hair Mn of children living in the vicinity of a ferro-manganese alloy production plant in the Great Salvador region, State of Bahia, Brazil and examine factors that influence this bioindicator of exposure. We examined 109 children in the age range of 1 to 10 years, living near the plant. Four separate housing areas were identified a priori on the bases of proximity to the emission sources and downwind location. A non-exposed group (n=43) of similar socioeconomic status was also evaluated. Mn hair (MnH) concentration was measured by graphite atomic absorption spectrometry (GFAAS). Possible confounding hematological parameters were also assessed. Mean MnH concentration was 15.20 μg/g (1.10–95.50 μg/g) for the exposed children and 1.37 μg/g (0.39–5.58 μg/g) for the non-exposed. For the former, MnH concentrations were 7.95±1.40 μg/g (farthest from the plant), 11.81±1.11 μg/g (mid-region), 34.43±8.66 μg/g (closest to the plant) and 34.22±9.15 μg/g (directly downwind). Multiple regression analysis on log transformed MnH concentrations for the exposed children derived a model that explained 36.8% of the variability. In order of importance, area of children’s residence, gender (girls > boys) and time of mother’s residence in the area at the birth of the child, were significantly associated with MnH. Post hoc analyses indicated 2 groupings for exposure areas, with those living closest to and downwind of the plant displaying higher MnH concentrations compared to the others. The contribution of the time the mother lived in the community prior to the child’s birth to the children’s current MnH suggests that in utero exposure may play a role. A study of neurobehavioral

  8. Optimization of the procedure for determining integral texture parameters of products from zirconium-based alloys using the orientation distribution function

    NASA Astrophysics Data System (ADS)

    Perlovich, Yu A.; Isaenkova, M. G.; Krymskaya, O. A.; Fesenko, V. A.; Babich, Y. A.

    2016-04-01

    Integral texture Kearns parameters, or f-parameters, are the one of the characteristics that is controlled during the tube production of Zr-based alloys now. These parameters define the anisotropy of physical and mechanical properties of the products. f-parameters are the sum of effective fractions of basal normals aligned in a selected sample direction. However, so far there is no standardized procedure for their calculation. The widespread availability of X-ray diffractometers, the high statistical significance of the results and the software development for texture analysis causes the optimality of the f-parameters determination by complete pole figures (0001) calculated through orientation distribution function (ODF). Accuracy analysis of the ODF extraction by several incomplete pole figures using LaboTex software was carried out in this paper. The comparison of the calculated data was performed with experimental complete pole figures (0001) obtained by «sewing» method. Various texture types, different number and combinations of incomplete pole figures were considered. For this purpose, 6 incomplete pole figures - - were registered for each of three mutually perpendicular surfaces of the CANDU-tube sample. By comparison of experimental and calculated by ODF complete pole figures as well as f-parameters, procedures of their determination were optimized for products from Zr-based alloys.

  9. The influence of the corrosion product layer generated on the high strength low-alloy steels welded by underwater wet welding with stainless steel electrodes in seawater

    NASA Astrophysics Data System (ADS)

    Bai, Qiang; Zou, Yan; Kong, Xiangfeng; Gao, Yang; Dong, Sheng; Zhang, Wei

    2017-02-01

    The high strength low-alloy steels are welded by underwater wet welding with stainless steel electrodes. The micro-structural and electrochemical corrosion study of base metal (BM), weld zone (WZ) and heat affected zone (HAZ) are carried out to understand the influence of the corrosion product layer generated on the high strength low-alloy steels welded by underwater wet welding with stainless steel electrodes, methods used including, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM). The results indicate that the WZ acts as a cathode and there is no corrosion product on it throughout the immersion period in seawater. The HAZ and BM acts as anodes. The corrosion rates of the HAZ and BM change with the immersion time increasing. In the initial immersion period, the HAZ has the highest corrosion rate because it has a coarse tempered martensite structure and the BM exhibites a microstructure with very fine grains of ferrite and pearlite. After a period of immersion, the BM has the highest corrosion rate. The reason is that the corrosion product layer on the HAZ is dense and has a better protective property while that on the BM is loose and can not inhibit the diffusion of oxygen.

  10. Molecular beam epitaxy of GaNAs alloys with high As content for potential photoanode applications in hydrogen production

    SciTech Connect

    Novikov, S. V.; Staddon, C. R.; Foxon, C. T.; Yu, K. M.; Broesler, R.; Hawkridge, M.; Liliental-Weber, Z.; Walukiewicz, W.; Denlinger, J.; Demchenko, I.

    2009-10-06

    The authors have succeeded in growing GaN1?xAsx alloys over a large composition range (0 < x < 0.8) by plasma-assisted molecular beam epitaxy. The enhanced incorporation of As was achieved by growing the films with high As{sub 2} flux at low (as low as 100 C) growth temperatures, which is much below the normal GaN growth temperature range. Using x-ray and transmission electron microscopy, they found that the GaNAs alloys with high As content x > 0.17 are amorphous. Optical absorption measurements together with x-ray absorption and emission spectroscopy results reveal a continuous gradual decrease in band gap from -3.4 to < 1 eV with increasing As content. The energy gap reaches its minimum of -0.8 eV at x - 0.8. The composition dependence of the band gap of the crystalline GaN{sub 1?x}As{sub x} alloys follows the prediction of the band anticrossing model (BAC). However, our measured band gap of amorphous GaN{sub 1?x}As{sub x} with 0.3 < x < 0.8 are larger than that predicted by BAC. The results seem to indicate that for this composition range the amorphous GaN{sub 1?x}As{sub x} alloys have short-range ordering that resembles random crystalline GaN{sub 1?x}As{sub x} alloys. They have demonstrated the possibility of the growth of amorphous GaN{sub 1?x}As{sub x} layers with variable As content on glass substrates

  11. Alloy dissolution in argon stirred steel

    NASA Astrophysics Data System (ADS)

    Webber, Darryl Scott

    Alloying is required for the production of all steel products from small castings to large beams. Addition of large quantities of bulk alloys can result in alloy segregation and inconsistent alloy recovery. The objective of this research was to better understand alloy dissolution in liquid steel especially as it relates to Missouri S&Ts' patented continuous steelmaking process. A 45-kilogram capacity ladle with a single porous plug was used to evaluate the effect of four experimental factors on alloy dissolution: alloy species, alloy size or form, argon flow rate, and furnace tap temperature. Four alloys were tested experimentally including Class I low carbon ferromanganese, nickel and tin (as a surrogate for low melting alloys) and Class II ferroniobium. The alloys ranged in size and form from granular to 30 mm diameter lumps. Experimental results were evaluated using a theoretically based numerical model for the steel shell period, alloy mixing (Class I) and alloy dissolution (Class II). A CFD model of the experimental ladle was used to understand steel motion in the ladle and to provide steel velocity magnitudes for the numerical steel shell model. Experiments and modeling confirmed that smaller sized alloys have shorter steel shell periods and homogenize faster than larger particles. Increasing the argon flow rate shortened mixing times and reduced the delay between alloy addition and the first appearance of alloy in the melt. In addition, for every five degree increase in steel bath temperature the steel shell period was shortened by approximately four percent. Class II ferroniobium alloy dissolution was an order of magnitude slower than Class I alloy mixing.

  12. Molecular hydrogen in a-Si: H

    NASA Astrophysics Data System (ADS)

    Carlos, W. E.; Taylor, P. C.

    1982-01-01

    Recently Conradi and Norberg have proposed that a small density of molecular hydrogen in a-Si: H films provides the relaxation mechanism which is responsible for a minimum in the proton spin-lattice relaxation time T1 at about 30 K. Although we are unable to observe an NMR line attributable to the H2, we are able to observe the conversion of the H2 molecules from the ortho state to the para state at 4.2 K. The process is bimolecular with a rate constant of 0.010 h-1. The existence of a large number of sites able to trap such a small molecule may provide an important insight into the defect structure of these films.

  13. Hot-Dip Galvanizing Alloys

    NASA Astrophysics Data System (ADS)

    Lynch, Richard F.

    1987-08-01

    Activity in the development of hotdip galvanizing alloys has been quite successful in achieving two major goals. First, the use of a zinc-nickel bath provides a workable solution to the problem of batch galvanizing reactive steels, to achieve both an attractive surface appearance and a thin, durable and protective coating. Second, for continuously galvanized steel products, specific zinc-aluminum alloys have provided a means to greatly increase corrosion resistance, increase the maximum use temperature of zinc coatings, achieve the fabrication of severely formed products without damage to the zinc alloy coating, and allow such products to be formed from prepainted as well as unpointed coated steel.

  14. Computer-assisted infrared spectra interpretation for amorphous silicon alloys

    NASA Astrophysics Data System (ADS)

    Kavak, Hamide; Esen, Ramazan

    2005-12-01

    A computer program for the structural interpretation of the infrared (IR) spectra is developed and tested. The interpretation of the IR spectra is made by using an hybrid system which includes library search and rule-based interpretation methods together. The computer programs were written in Pascal Codes. The prototype IR library of silicon alloys includes amorphous silicon (a-Si), amorphous silicon dioxide (a-SiOx), amorphous silicon nitride (a-Si3N4) and amorphous silicon carbide (a-SiC) references. The known spectra of these compounds were fed into the system as an unknown samples. The performance of the developed program was evaluated on a test set of 157 spectra and the percentages of successful identification ranged between 78% and 99% for different alloys.

  15. Defect formation mechanism during PECVD of a-Si:H

    SciTech Connect

    Maeda, Keiji; Umezu, Ikurou

    1997-07-01

    Defect formation mechanism in a-Si:H during PECVD at substrate temperature below 250 C is considered to be breaking of weak bonds in the Urbach tail. To break weak bonds, an extra energy is necessary. This energy is supplied by the reaction energy of SiH{sub 3} precursor at the growing surface incorporating SiH{sub 2} into the network. The defect density is experimentally shown to be proportional to a product of the energy supply frequency, i.e., SiH{sub 2} density, and the weak bond density which is obtained by the Urbach energy. By analysis using the configurational coordinate diagram the energy level of the broken weak bond is determined to be 0.2 eV above the valence band mobility edge. There is similarity of the defect formation mechanism during deposition to that of the Staebler-Wronski effect.

  16. VANADIUM ALLOYS

    DOEpatents

    Smith, K.F.; Van Thyne, R.J.

    1959-05-12

    This patent deals with vanadium based ternary alloys useful as fuel element jackets. According to the invention the ternary vanadium alloys, prepared in an arc furnace, contain from 2.5 to 15% by weight titanium and from 0.5 to 10% by weight niobium. Characteristics of these alloys are good thermal conductivity, low neutron capture cross section, good corrosion resistance, good welding and fabricating properties, low expansion coefficient, and high strength.

  17. BRAZING ALLOYS

    DOEpatents

    Donnelly, R.G.; Gilliland, R.G.; Slaughter, G.M.

    1963-02-26

    A brazing alloy which, in the molten state, is characterized by excellent wettability and flowability, said alloy being capable of forming a corrosion resistant brazed joint wherein at least one component of said joint is graphite and the other component is a corrosion resistant refractory metal, said alloy consisting essentially of 20 to 50 per cent by weight of gold, 20 to 50 per cent by weight of nickel, and 15 to 45 per cent by weight of molybdenum. (AEC)

  18. Magnesium and magnesium alloys

    SciTech Connect

    Avedesian, M.; Baker, H.

    1998-12-31

    This new handbook is the most comprehensive publication of engineering information on commercial magnesium alloys under one cover in the last sixty years. Prepared with the cooperation of the International Magnesium Association, it presents the industrial practices currently used throughout the world, as well as the properties of the products critical to their proper application. Contents include: general characteristics; physical metallurgy; melting, refining, alloying, recycling, and powder production; casting; heat treatment; forging, rolling, and extrusion; semisolid processing; forming; joining; cleaning and finishing; selection, application, and properties of grades and alloys; design considerations; mechanical behavior and wear resistance; fatigue and fracture-mechanics; high-temperature strength and creep; corrosion and stress-corrosion cracking; specification.

  19. Corrosion behaviors and effects of corrosion products of plasma electrolytic oxidation coated AZ31 magnesium alloy under the salt spray corrosion test

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Huang, Zhiquan; Yan, Qin; Liu, Chen; Liu, Peng; Zhang, Yi; Guo, Changhong; Jiang, Guirong; Shen, Dejiu

    2016-08-01

    The effects of corrosion products on corrosion behaviors of AZ31 magnesium alloy with a plasma electrolytic oxidation (PEO) coating were investigated under the salt spray corrosion test (SSCT). The surface morphology, cross-sectional microstructure, chemical and phase compositions of the PEO coating were determined using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction analysis (XRD), respectively. Further, the corrosion process of the samples under the SSCT was examined in a non-aqueous electrolyte (methanol) using electrochemical impedance spectroscopy (EIS) coupled with equivalent circuit. The results show that the inner layer of the coating was destroyed firstly and the corrosion products have significant effects on the corrosion behaviors of the coating. The results above are discussed and an electrochemical corrosion model is proposed in the paper.

  20. PILOT EVALUATION OF VANADIUM ALLOYS.

    DTIC Science & Technology

    ARCS, SHEETS, ROLLING(METALLURGY), HIGH TEMPERATURE, SCIENTIFIC RESEARCH, COMPRESSIVE PROPERTIES, DUCTILITY, CREEP, OXIDATION, COATINGS , SILICIDES , HARDNESS, WELDING, EXTRUSION, TANTALUM ALLOYS, MOLYBDENUM ALLOYS....VANADIUM ALLOYS, * NIOBIUM ALLOYS, MECHANICAL PROPERTIES, MECHANICAL PROPERTIES, TITANIUM ALLOYS, ZIRCONIUM ALLOYS, CARBON ALLOYS, MELTING, ELECTRIC

  1. Nonswelling alloy

    DOEpatents

    Harkness, S.D.

    1975-12-23

    An aluminum alloy containing one weight percent copper has been found to be resistant to void formation and thus is useful in all nuclear applications which currently use aluminum or other aluminum alloys in reactor positions which are subjected to high neutron doses.

  2. URANIUM ALLOYS

    DOEpatents

    Seybolt, A.U.

    1958-04-15

    Uranium alloys containing from 0.1 to 10% by weight, but preferably at least 5%, of either zirconium, niobium, or molybdenum exhibit highly desirable nuclear and structural properties which may be improved by heating the alloy to about 900 d C for an extended period of time and then rapidly quenching it.

  3. ZIRCONIUM ALLOY

    DOEpatents

    Wilhelm, H.A.; Ames, D.P.

    1959-02-01

    A binary zirconiuin--antimony alloy is presented which is corrosion resistant and hard containing from 0.07% to 1.6% by weight of Sb. The alloys have good corrosion resistance and are useful in building equipment for the chemical industry.

  4. Kinetics of a-Si:H bulk defect and a-Si:H/c-Si interface-state reduction

    NASA Astrophysics Data System (ADS)

    de Wolf, Stefaan; Ballif, Christophe; Kondo, Michio

    2012-03-01

    Low-temperature annealing of hydrogenated amorphous silicon (a-Si:H) is investigated. An identical energy barrier is found for the reduction of deep defects in the bulk of a-Si:H films and at the interface such layers form with crystalline Si (c-Si) surfaces. This finding gives direct physical evidence that the defects determining a-Si:H/c-Si interface recombination are silicon dangling bonds and that also kinetically this interface has no unique features compared to the a-Si:H bulk.

  5. COST-EFFECTIVE METHOD FOR PRODUCING SELF SUPPORTED PALLADIUM ALLOY MEMBRANES FOR USE IN EFFICIENT PRODUCTION OF COAL DERIVED HYDROGEN

    SciTech Connect

    J. Arps; K. Coulter

    2006-09-30

    In the past quarter, we have conducted additional characterization and permeation tests on different Pd alloy membranes including PdCuTa ternary alloy materials. We attempted to address some discrepancies between SwRI{reg_sign} and CSM relating to PdCu stoichiometry by preparing a range of PdCu membranes with compositions from {approx}58-65 at% Pd (bal. Cu). While some difficulties in cutting and sealing these thin membranes at CSM continue, some progress has been made in identifying improved membrane support materials. We have also completed an initial cost analysis for large-scale vacuum deposition and fabrication of thin Pd ally membranes and project that the process can meet DOE cost targets. Minimal progress was made in the past quarter relating to the testing of prototype membrane modules at Idatech. In the past quarter Idatech was acquired by a UK investment firm, which we believe may have impacted the ability of key technical personnel to devote sufficient time to support this effort. We are hopeful their work can be completed by the end of the calendar year.

  6. Defects in a-Si and a-Si:H: A numerical study

    NASA Astrophysics Data System (ADS)

    Knief, Simone; von Niessen, Wolfgang; Koslowski, Thorsten

    1998-08-01

    We present a numerical study of the electronic properties of various structural models of amorphous silicon and hydrogenated amorphous silicon. Starting from an ideal random network, dangling bonds, floating bonds, double bonds, microvoids, hydrogenated dangling bonds, and hydrogenated floating bonds are introduced. The concentrations of these defects can be varied independently, the amount of disorder introduced to the system is therefore strictly controllable. Two continuous random networks, the vacancy model of Duffy, Boudreaux, and Polk and the bond switching model of Wooten, Winer, and Weaire (WWW model) are investigated. For the relaxation of the structures the potentials of Keating and of Stillinger and Weber are employed. The electronic structure is described by a tight-binding Hamiltonian; the localized or extended character of the eigenstates is investigated via a scaling approach. The vacancy model shows a band gap for small defect concentrations but this fills up with increasing disorder. Similar behavior is found for the case of the other models. In general defects introduce states into the gap region of a-Si, where the dangling bonds lead to the largest density of states in the gap region for a given defect concentration. This model turns out to be unique. For small system sizes an impurity band results that dramatically changes its character for large systems above 4000 atoms to a nearly uniform density of states as observed experimentally. In a-Si:H the dangling and floating bonds are removed and a mobility gap results with a width in good agreement with experiment. The experimentally observed tailing of the band into the gap region (first linear, then exponential) is well described only for the a-Si:H model derived from the vacancy model and for very large system sizes above 4000 atoms. The WWW model does not lead to this tail behavior. Localized states are found at all band edges but states at the bottom of the conduction band are more strongly

  7. [Evaluation of occupational exposure to nickel and other metals based on the analysis of air in the production of nickel alloys].

    PubMed

    Dobecki, M; Matych, S; Kamecki, R; Matczak, W

    1988-01-01

    The measurements of air pollutions in the rolling mill of non-ferrous metals aimed at the evaluation of occupational exposure to nickel and other metals (Cu, Zn, Mn, Mg) used during the production of nickel alloys. It was found that nickel fumes and dusts concentration can be the only hazardous factor for the workers' health. The majority (ca 85%) of the crew of 28 workers is exposed to the nickel concentration in air exceeding 0.05 mg/m3. Smelters (8 persons) at the stand of 97-99% nickel smelting are at the highest risk of the loss of health; average exposure of this group during 8 hours' shift may surpass 2 mg Ni/m3. Mean concentration in air of the fumes and dusts of copper, zinc, manganese and magnesium do not make a hygienic problem.

  8. Aluminum alloy

    NASA Technical Reports Server (NTRS)

    Blackburn, Linda B. (Inventor); Starke, Edgar A., Jr. (Inventor)

    1989-01-01

    This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

  9. Aluminum alloy

    NASA Technical Reports Server (NTRS)

    Blackburn, Linda B. (Inventor); Starke, Edgar A., Jr. (Inventor)

    1989-01-01

    This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

  10. PLUTONIUM ALLOYS

    DOEpatents

    Chynoweth, W.

    1959-06-16

    The preparation of low-melting-point plutonium alloys is described. In a MgO crucible Pu is placed on top of the lighter alloying metal (Fe, Co, or Ni) and the temperature raised to 1000 or 1200 deg C. Upon cooling, the alloy slug is broke out of the crucible. With 14 at. % Ni the m.p. is 465 deg C; with 9.5 at. % Fe the m.p. is 410 deg C; and with 12.0 at. % Co the m.p. is 405 deg C. (T.R.H.) l6262 l6263 ((((((((Abstract unscannable))))))))

  11. Testing and prediction of erosion-corrosion for corrosion resistant alloys used in the oil and gas production industry

    NASA Astrophysics Data System (ADS)

    Rincon, Hernan E.

    The corrosion behavior of CRAs has been thoroughly investigated and documented in the public literature by many researchers; however, little work has been done to investigate erosion-corrosion of such alloys. When sand particles are entrained in the flow, the degradation mechanism is different from that observed for sand-free corrosive environment. There is a need in the oil and gas industry to define safe service limits for utilization of such materials. The effects of flow conditions, sand rate, pH and temperature on the erosion-corrosion of CRAs were widely studied. An extensive experimental work was conducted using scratch tests and flow loop tests using several experimental techniques. At high erosivity conditions, a synergistic effect between erosion and corrosion was observed. Under the high sand rate conditions tested, erosivity is severe enough to damage the passive layer protecting the CRA thereby enhancing the corrosion rate. In most cases there is likely a competition between the rates of protective film removal due to mechanical erosion and protective film healing. Synergism occurs for each of the three alloys examined (13Cr and Super13Cr and 22Cr); however, the degree of synergism is quite different for the three alloys and may not be significant for 22Cr for field conditions where erosivities are typically much lower that those occurring in the small bore loop used in this research. Predictions of the corrosion component of erosion-corrosion based on scratch test data compared reasonably well to test results from flow loops for the three CRAs at high erosivity conditions. Second order behavior appears to be an appropriate and useful model for representing the repassivation process of CRAs. A framework for a procedure to predict penetration rates for erosion-corrosion conditions was developed based on the second order model behavior observed for the re-healing process of the passive film of CRAs and on computational fluid dynamics (CFD) simulations

  12. Tungsten and tungsten-alloy powder metallurgy: Powder production and applications-excluding lamps. November 1971-July 1989 (Citations from the US Patent data base). Report for November 1971-July 1989

    SciTech Connect

    Not Available

    1989-10-01

    This bibliography contains citations of selected patents concerning the preparation of metallic and ceramic powders of tungsten and tungsten alloys including various applications of these materials. The hydrogen reduction of tungsten compounds together with alloying-element compounds produce forms with characteristics of high density, hardness, wear resistance, high melting points, and abrasiveness. Topics include production of various cathodes, heaters, filament wires, electrical contacts, acoustic absorbers, high-density sheets and coatings, hard penetrators, and tungsten carbide and metallized ceramics. Tungsten halogen lamps are examined in a separate bibliography. (Contains 60 citations fully indexed and including a title list.)

  13. COST-EFFECTIVE METHOD FOR PRODUCING SELF SUPPORTED PALLADIUM ALLOY MEMBRANES FOR USE IN EFFICIENT PRODUCTION OF COAL DERIVED HYDROGEN

    SciTech Connect

    J. Arps

    2006-01-01

    In the past quarter, significant progress has been made in optimize the deposition and release characteristics of ultrathin (less than 4 micron) membranes from rigid silicon substrates. Specifically, we have conducted a series of statistically designed experiments to examine the effects of plasma cleaning and compliant layer deposition conditions on the stress, release and pinhole density of membranes deposited on 4 inch and 6 inch round substrates. With this information we have progressed to the deposition and release of ultra-thin membranes from 12-inch diameter (113 sq. in.) rigid substrates, achieving a key milestone for large-area membrane fabrication. Idatech received and is beginning preparations to test the Pd alloy membranes fabricated at SwRI the previous quarter. They are currently evaluating alternate gasketing methods and support materials that will allow for effective sealing and mounting of such thin membranes. David Edlund has also recently left Idatech and Bill Pledger (Chief Engineer) has replaced him as the primary technical point of contact. At Idetech's request a small number of additional 16 sq. in, samples were provided in a 2 in. by 8 in. geometry for use in a new module design currently under development. Recent work at the Colorado School of Mines has focused on developing preconditioning methods for thin Pd alloy membranes (6 microns or less) and continuing tests of thin membranes produced at SwRI. Of particular note, a 300-hour short-term durability study was completed over a range of temperatures from 300-450 C on a foil that showed perfect hydrogen selectivity throughout the entire test. With a 20 psi driving force, pure hydrogen flow rates ranged from 500 to 700 cc/min. Calculated at DOE specified conditions, the H{sub 2} flux of this membrane exceeded the 2010 Fossil target value of 200 SCFH/ft{sup 2}.

  14. Characterization of the visible photoluminescence from porous a-Si:H and porous a-Si:C:H thin films

    SciTech Connect

    Estes, M.J.; Hirsch, L.R.; Wichart, S.; Moddel, G.

    1996-12-31

    The authors report on the influence of doping, temperature, porosity, and bandgap on the visible photoluminescence properties of anodically-etched porous a-Si:H and a-Si:C:H thin films. Only boron-doped, p-type a-Si:H or a-Si:C:H samples exhibited any visible photoluminescence. The authors see evidence of discrete defect or impurity levels in temperature-dependent luminescence measurements. Unlike in porous crystalline silicon, they see no correlation of luminescence energy with porosity. The authors do, though, observe a correlation of luminescence energy with bandgap of the starting a-Si:C:H films. They discuss the implication of these observations on the nature of the luminescence mechanism.

  15. COATED ALLOYS

    DOEpatents

    Harman, C.G.; O'Bannon, L.S.

    1958-07-15

    A coating is described for iron group metals and alloys, that is particularly suitable for use with nickel containing alloys. The coating is glassy in nature and consists of a mixture containing an alkali metal oxide, strontium oxide, and silicon oxide. When the glass coated nickel base metal is"fired'' at less than the melting point of the coating, it appears the nlckel diffuses into the vitreous coating, thus providing a closely adherent and protective cladding.

  16. BRAZING ALLOYS

    DOEpatents

    Donnelly, R.G.; Gilliland, R.G.; Slaughter, G.M.

    1962-02-20

    A brazing alloy is described which, in the molten state, is characterized by excellent wettability and flowability and is capable of forming a corrosion-resistant brazed joint. At least one component of said joint is graphite and the other component is a corrosion-resistant refractory metal. The brazing alloy consists essentially of 40 to 90 wt % of gold, 5 to 35 wt% of nickel, and 1 to 45 wt% of tantalum. (AEC)

  17. Environmental fatigue in aluminum-lithium alloys

    NASA Technical Reports Server (NTRS)

    Piascik, Robert S.

    1992-01-01

    Aluminum-lithium alloys exhibit similar environmental fatigue crack growth characteristics compared to conventional 2000 series alloys and are more resistant to environmental fatigue compared to 7000 series alloys. The superior fatigue crack growth behavior of Al-Li alloys 2090, 2091, 8090, and 8091 is due to crack closure caused by tortuous crack path morphology and crack surface corrosion products. At high R and reduced closure, chemical environment effects are pronounced resulting in accelerated near threshold da/dN. The beneficial effects of crack closure are minimized for small cracks resulting in rapid growth rates. Limited data suggest that the 'chemically small crack' effect, observed in other alloy system, is not pronounced in Al-Li alloys. Modeling of environmental fatigue in Al-Li-Cu alloys related accelerated fatigue crack growth in moist air and salt water to hydrogen embrittlement.

  18. Absorption in a-Si/SiO2 Superlattices

    NASA Astrophysics Data System (ADS)

    Kilpelä, O.; Karppinen, M.; Novikov, S.; Sokolov, V.; Yliniemi, S.

    a-Si/SiO2 superlattices were grown on quartz by MBD (Molecular Beam Deposition) using in situ oxidation by an RF-plasma source. The a-Si layer thicknesses were varied from 0.5-2.5nm while the SiO2 layer thicknesses (1.0nm) were kept constant. Optical transmission and reflection measurements were performed on these samples at room temperature. The recorded spectra were then analyzed with a commercial optical thin film analysis program. The band gaps were derived from constant-n and non-constant-n forms of Tauc and Cody laws. The observed blueshift of the band gap, with decreasing a-Si layer thickness, is attributed to quantum confinement in the a-Si sublayers.

  19. Electron cyclotron resonance microwave plasma deposition of a-Si:H and a-SiC:H films

    NASA Technical Reports Server (NTRS)

    Shing, Y. H.; Pool, F. S.

    1991-01-01

    The paper reports electron cyclotron resonance (ECR) deposition of a-Si:H and a-SiC:H thin films using SiH4, CH4, and hydrogen mixed gas plasmas. The ECR deposition conditions were investigated in the pressure region of 0.1 to 100 mtorr, and the film properties were characterized by light and dark conductivity measurements, XRD, Raman spectroscopy, optical transmission, and IR spectroscopy. In addition, the hydrogen dilution effect on ECR-deposited a-SiC:H was investigated.

  20. Elevated temperature aluminum alloys

    NASA Technical Reports Server (NTRS)

    Meschter, Peter (Inventor); Lederich, Richard J. (Inventor); O'Neal, James E. (Inventor)

    1989-01-01

    Three aluminum-lithium alloys are provided for high performance aircraft structures and engines. All three alloys contain 3 wt % copper, 2 wt % lithium, 1 wt % magnesium, and 0.2 wt % zirconium. Alloy 1 has no further alloying elements. Alloy 2 has the addition of 1 wt % iron and 1 wt % nickel. Alloy 3 has the addition of 1.6 wt % chromium to the shared alloy composition of the three alloys. The balance of the three alloys, except for incidentql impurities, is aluminum. These alloys have low densities and improved strengths at temperatures up to 260.degree. C. for long periods of time.

  1. Applications of a-Si:H radiation detectors

    SciTech Connect

    Fujieda, I.; Cho, G.; Conti, M.; Drewery, J.; Kaplan, S.N.; Perez-Mendez, V.; Qureshi, S.; Street, R.A.

    1989-07-01

    Device structures and operation principles are described for detecting various kinds of radiation with hydrogenated amorphous silicon (a-Si:H) layers. With some new configurations such as the buried p-i-n structure and the use of interdigitated electrodes, the a-Si:H radiation detectors will find their applications in many fields of science. Some applications in high energy physics, medical imaging, materials sciences and life sciences are discussed in this paper. 41 refs., 7 figs., 1 tab.

  2. Material properties and device evaluations of ECR-deposited a-Si:H and a-SiC:H films

    NASA Technical Reports Server (NTRS)

    Shing, Y. H.; Pool, F. S.; Essick, J. M.

    1991-01-01

    Device-quality a-Si:H and a-SiC:H films have been deposited using electron cyclotron resonance (ECR) microwave plasmas of SiH4, CH4, and H2 mixtures. Typical material properties of ECR-deposited, photosensitive a-Si:H films are: (1) high photosensitivity up to 2 x 106 with a photoconductivity of 10 exp -5 to 10 exp -4/(Ohm-cm), (2) a Tauc gap of 1.75 to 1.85 eV, (3) an Urbach slope of 50-60 meV determined by the constant photocurrent method, and (4) an integrated defect density of 1-2 x 10 exp 16/cu cm determined by junction capacitance measurements. Highly conductive, p-type a-SiC:H films have been produced by ECR plasmas with a conductivity of 0.2/(Ohm-cm).

  3. Material properties and device evaluations of ECR-deposited a-Si:H and a-SiC:H films

    NASA Technical Reports Server (NTRS)

    Shing, Y. H.; Pool, F. S.; Essick, J. M.

    1991-01-01

    Device-quality a-Si:H and a-SiC:H films have been deposited using electron cyclotron resonance (ECR) microwave plasmas of SiH4, CH4, and H2 mixtures. Typical material properties of ECR-deposited, photosensitive a-Si:H films are: (1) high photosensitivity up to 2 x 106 with a photoconductivity of 10 exp -5 to 10 exp -4/(Ohm-cm), (2) a Tauc gap of 1.75 to 1.85 eV, (3) an Urbach slope of 50-60 meV determined by the constant photocurrent method, and (4) an integrated defect density of 1-2 x 10 exp 16/cu cm determined by junction capacitance measurements. Highly conductive, p-type a-SiC:H films have been produced by ECR plasmas with a conductivity of 0.2/(Ohm-cm).

  4. Orthodontic silver brazing alloys.

    PubMed

    Brockhurst, P J; Pham, H L

    1989-10-01

    Orthodontic silver brazing alloys suffer from the presence of cadmium, excessive flow temperatures, and crevice corrosion on stainless steel. Seven alloys were examined. Two alloys contained cadmium. The lowest flow temperature observed was 629 degrees C for a cadmium alloy and 651 degrees C for two cadmium free alloys. Three alloys had corrosion resistance superior to the other solders. Addition of low melting temperature elements gallium and indium reduced flow temperature in some cases but produced brittleness in the brazing alloy.

  5. Production of Porous β-Type Ti-40Nb Alloy for Biomedical Applications: Comparison of Selective Laser Melting and Hot Pressing.

    PubMed

    Zhuravleva, Ksenia; Bönisch, Matthias; Prashanth, Konda Gokuldoss; Hempel, Ute; Helth, Arne; Gemming, Thomas; Calin, Mariana; Scudino, Sergio; Schultz, Ludwig; Eckert, Jürgen; Gebert, Annett

    2013-12-06

    We used selective laser melting (SLM) and hot pressing of mechanically-alloyed β-type Ti-40Nb powder to fabricate macroporous bulk specimens (solid cylinders). The total porosity, compressive strength, and compressive elastic modulus of the SLM-fabricated material were determined as 17% ± 1%, 968 ± 8 MPa, and 33 ± 2 GPa, respectively. The alloy's elastic modulus is comparable to that of healthy cancellous bone. The comparable results for the hot-pressed material were 3% ± 2%, 1400 ± 19 MPa, and 77 ± 3 GPa. This difference in mechanical properties results from different porosity and phase composition of the two alloys. Both SLM-fabricated and hot-pressed cylinders demonstrated good in vitro biocompatibility. The presented results suggest that the SLM-fabricated alloy may be preferable to the hot-pressed alloy for biomedical applications, such as the manufacture of load-bearing metallic components for total joint replacements.

  6. Mechanically alloyed Ni-base alloys for heat-resistant applications

    SciTech Connect

    Wilson, R.K.; Fischer, J.J.

    1995-12-31

    INCONEL alloys MA 754 and MA 758 are nickel-base oxide dispersion-strengthened (ODS) alloys made by mechanical alloying (MA). Commercial use of Ma Ni-base alloys to date has been predominantly in aerospace applications of alloy MA 754 as turbine engine vanes. Both alloys are suitable for industrial heat treating components and other heat resistant alloy applications. Field trials and commercial experience in such applications of MA alloys are being gained while high temperature property characterization and new product form development continue. Hot isostatic pressing (HIP) is the standard consolidation method for billets from which large bar and plate are produced for industrial applications of MA. This paper describes production of standard mill shapes from HIP billets, and it presents information on current and potential uses of MA alloys in applications such as: skid rails for use in high temperature walking beam furnaces, heat treating furnace components, components for handling molten glass, and furnace tubes. The paper includes comparison of the properties obtained in alloy MA 754 (20% Cr) and alloy MA 758 (30% Cr).

  7. Comparison of crystallization kinetics in a-Si/Cu and a-Si/Al bilayer recording films under thermal annealing and pulsed laser irradiation

    NASA Astrophysics Data System (ADS)

    Her, Yung-Chiun; Chen, Chih-Wei; Wu, Chun-Lin

    2006-06-01

    Under thermal annealing, the crystallization temperatures of a-Si in a-Si/Cu and a-Si/Al bilayer recording films were significantly reduced to around 485 and 357 °C, respectively, and the activation energies for crystallization were reduced to about 3.3 eV. The formation of Cu3Si phase prior to crystallization of a-Si was found to occur at around 175 °C in a-Si/Cu, while no Al silicide was observed in a-Si/Al before crystallization of a-Si. The reaction exponents for a-Si/Cu and a-Si/Al were determined to be around 1.8 and 1.6, respectively, corresponding to a crystallization process in which grain growth occurs with nucleation, and the nucleation rate decreases with the progress of grain growth. Under pulsed laser irradiation, the precipitation of Cu3Si phases and crystallization of a-Si were observed in a-Si/Cu, while the crystallization and reamorphization of a-Si took place sequentially in a-Si/Al. The reaction exponents for a-Si/Cu and a-Si/Al, determined to be about 2.0 and 2.2, respectively, are slightly higher than those under thermal annealing, indicating that the crystallization processes of a-Si/Cu and a-Si/Al under pulsed laser irradiation are similar to those under thermal annealing. However, the decrease of nucleation rate with the progress of grain growth is slower. At the same time, the activation energies for crystallization of a-Si/Cu and a-Si/Al, estimated to be about 0.18 and 0.22 eV, respectively, are nearly an order of magnitude lower than those under thermal annealing. This may be explained by the explosive crystallization of a-Si by mechanical impact, with a high power pulsed laser.

  8. a-Si:F and a-Si:F:H prepared by ion-beam-assisted reactive deposition

    NASA Astrophysics Data System (ADS)

    Zhang, S.; Brodie, D. E.

    1992-08-01

    a-Si:F and a-Si:F:H films have been prepared by ion-beam-assisted deposition using SiF4, SiH4+Ar, or SiF4+SiH4 as the gases for the ion source. Fluorine in a-Si eliminates some dangling bonds, increases the optical gap, and decreases the dark conductivity. The results are influenced mainly by the ion-beam energy used. The a-Si:F films do not exhibit an activated conductivity even up to 150 °C, and no photoconductivity could be detected. However, film properties were significantly improved when a very small amount of H was added to the a-Si:F and much less than 1 at. % H produced films that were photoconducting and had activated conductivities. The properties of these a-Si:F:H are strongly dependent on both the fluorine concentration CF and the hydrogen concentration CH. The deposition rate decreases with increasing SiF4 content in the source gas, and neither CF nor CH vary linearly with the change in the source gas ratio SiH4/(SiF4+SiH4). Hence, CH must be known and controlled in order to evaluate the effect of fluorine on the film's properties. By studying a series of a-Si:F:H samples containing the same CH, it is noted that incorporating some F does improve the film's electrical properties. Annealing experiments suggest that an observed peak at 2100 cm-1 in the IR spectra of these a-Si:F:H films is not completely due to SiH2, as has been suggested by others.

  9. High performance a-Si solar cells and new fabrication methods for a-Si solar cells

    NASA Astrophysics Data System (ADS)

    Nakano, S.; Kuwano, Y.; Ohnishi, M.

    1986-12-01

    The super chamber, a separated UHV reaction-chamber system has been developed. A conversion efficiency of 11.7% was obtained for an a-Si solar cell using a high-quality i-layer deposited by the super chamber, and a p-layer fabricated by a photo-CVD method. As a new material, amorphous superlattice-structure films were fabricated by the photo-CVD method for the first time. Superlattice structure p-layer a-Si solar cells were fabricated, and a conversion efficiency of 10.5% was obtained. For the fabrication of integrated type a-Si solar cell modules, a laser pattering method was investigated. A thermal analysis of the multilayer structure was done. It was confirmed that selective scribing for a-Si, TCO and metal film is possible by controlling the laser power density. Recently developed a-Si solar power generation systems and a-Si solar cell roofing tiles are also described.

  10. Charge collection in a-Si:H/a-Si{sub 1-x}C{sub x} multilayers photodetectors

    SciTech Connect

    Jing, T.; Drewray, J.; Hong, W.S.; Lee, H.; Kaplan, S.N.; Mireshghi, A.; Perez-Mendez, V.; Delgado, J.C.; Bertomeu, J.

    1994-04-01

    Amorphous semiconductors have been used as thin film transistor(TFT), solar cell, phototransistors. In this paper we study the charge collected properties of a-Si:H/a-Si{sub 1-x}C:H{sub x} multilayer pin photodiode. In a-Si:H pin photodiode, the photogenerated carriers can be totally collected under strong electric field under reverse bias. However, our measurements show that in the a-Si:H/a-Si{sub l-x}C:H{sub x} multilayer pin photodiode photogenerated electrons and holes drift toward the electrodes under a certain bias, the total collected charge shows no saturation with bias and exhibits a continuous increase with reverse bias. We classify that the device works at two regions. In Region 1, the device behaves like a photodiode. This charge collection efficiency drop from theoretical value may indicate charge capture or confinement at the interfaces and trapping at the a-Si:H potential wells. These charges trapped or confined can be released at the interface and quantum well at higher electric field. In Region 2, above a critical bias voltage, the device works as a breakdown diode with a series photosensitive resistor which contributes higher collection efficiency, namely optical gain greater than unity.

  11. Effect of pH treatment on K-shell x-ray intensity ratios and K-shell x-ray-production cross sections in ZnCo alloys

    SciTech Connect

    Kup Aylikci, N.; Aylikci, V.; Tirasoglu, E.; Cengiz, E.; Kahoul, A.; Karahan, I. H.

    2011-10-15

    In this study, empirical and semiempirical K-shell fluorescence yields ({omega}{sub K}) and K{beta}/K{alpha} intensity ratios from the available experimental data for elements with 23{<=}Z{<=}30 were calculated to compare them with elements in different alloys. The experimental data are fitted using the quantity [{omega}{sub K}/(1-{omega}{sub K})]{sup 1/4} vs Z to deduce the empirical K-shell fluorescence yields and K{beta}/K{alpha} intensity ratios. The empirical and semiempirical K-shell fluorescence yield values were used to calculate the K x-ray-production cross-section values for pure Co and Zn elements. Also, {sigma}{sub K{alpha}}, {sigma}{sub K{beta}} production cross sections and K{beta}/K{alpha} intensity ratios of Co and Zn have been measured in pure metals and in different alloy compositions which have different pH values. The samples were excited by 59.5-keV {gamma} rays from a {sup 241}Am annular radioactive source. K x rays emitted by samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV. The effect of pH values on alloy compositions and the effect of alloying on the fluorescence parameters of Co and Zn were investigated. The x-ray fluorescence parameters of Co and Zn in the alloying system indicate significant differences with respect to the pure metals. These differences are attributed to the reorganization of valence shell electrons and/or charge transfer phenomena.

  12. Tin induced a-Si crystallization in thin films of Si-Sn alloys

    SciTech Connect

    Neimash, V. E-mail: oleks.goushcha@nuportsoft.com; Poroshin, V.; Goushcha, A. O. E-mail: oleks.goushcha@nuportsoft.com; Shepeliavyi, P.; Yukhymchuk, V.; Melnyk, V.; Kuzmich, A.; Makara, V.

    2013-12-07

    Effects of tin doping on crystallization of amorphous silicon were studied using Raman scattering, Auger spectroscopy, scanning electron microscopy, and X-ray fluorescence techniques. Formation of silicon nanocrystals (2–4 nm in size) in the amorphous matrix of Si{sub 1−x}Sn{sub x}, obtained by physical vapor deposition of the components in vacuum, was observed at temperatures around 300 °C. The aggregate volume of nanocrystals in the deposited film of Si{sub 1−x}Sn{sub x} exceeded 60% of the total film volume and correlated well with the tin content. Formation of structures with ∼80% partial volume of the nanocrystalline phase was also demonstrated. Tin-induced crystallization of amorphous silicon occurred only around the clusters of metallic tin, which suggested the crystallization mechanism involving an interfacial molten Si:Sn layer.

  13. Powder metallurgy of vanadium and its alloys (review)

    SciTech Connect

    Radomysel'skii, I.D.; Solntsev, V.P.; Evtushenko, O.V.

    1987-10-01

    This article reviews the current powder metallurgy technology of vanadium and its alloys. Data are given on sintering, compacting, electrowinning and other current production techniques, as well as on the corrosion behavior and mechanical and physical properties of alloys produced by these different methods. The use of vanadium alloys as reactor and jet engine materials is also briefly discussed.

  14. The Fatigue of Powder Metallurgy Alloys.

    DTIC Science & Technology

    1982-01-08

    characteristics of an ingot metallurgy product, 7075 -T76. In all alloys high closure levels are observed atR=0.05 in the near threshold region, an...of two aluminum P/M alloys, X7090 and X7091. For comparison purposes, the ingot metallurgy (I/M) alloy 7075 -76 has also been tested. The results of...described in this report were obtained in extruded form from L Alcoa via Lockheed-California Company. These alloys are: P/M X7090-T6 P/M X7091-T7E69 I/M 7075

  15. High-temperature property data: Ferrous alloys

    SciTech Connect

    Rothman, M.F.

    1987-01-01

    In this book over 250 alloys are organized by AISI number into 10 major sections: Irons, Carbon Steels, Alloy Steels, Low Alloy Constructional Steels, Ultra High Strength Steels, Tool Steels, Maraging Steels, Wrought Stainless Steels, Heat Resistnat Casting Alloys, and Iron Based Rought Superalloys. Each alloy record lists the designation, specifications, UNS number, composition, product forms and a comment on the high-temperature properties and applications. Referenced data is then given for physical properties such as density, specific heat, thermal conductivity, thermal expansion, electrical conductivity, Poisson's ratio, moduli of elasticity and rigidity, etc. Mechanical properties follow, and include tensile properties, shearing and bearing properties, impact properties, creep, stress rupture and stress relaxation and fatigue properties. The last part of the alloy record gives other effects of temperature, such as hot hardness, corrosion, and growth.

  16. First-principles simulations of vibrational decay and lifetimes in a -Si:H and a -Si:D

    NASA Astrophysics Data System (ADS)

    Atta-Fynn, Raymond; Drabold, David A.; Elliott, Stephen R.; Biswas, Parthapratim

    2017-03-01

    Phonon lifetime in materials is an important observable that conveys basic information about structure, dynamics, and anharmonicity. Recent vibrational transient-grating measurements, using picosecond infrared pulses from free-electron lasers, have demonstrated that the vibrational-population decay rates of localized high-frequency stretching modes (HSMs) in hydrogenated and deuterated amorphous silicon (a -Si:H/D) increase with temperature and the vibrational energy redistributes among the bending modes of Si in a -Si:H/D. Motivated by this observation, we address the problem from first-principles density-functional calculations and study the time evolution of the vibrational-population decay in a -Si:H/D, the average decay times, and the possible decay channels for the redistribution of vibrational energy. The average lifetimes of the localized HSMs in a -Si:H and a -Si:D are found to be approximately 51-92 ps and 50-78 ps, respectively, in the temperature range of 25-200 K, which are consistent with experimental data. A weak temperature dependence of the vibrational-population decay rates has been observed via a slight increase of the decay rates with temperature, which can be attributed to stimulated emission and increased anharmonic coupling between the normal modes at high temperature.

  17. Well-Passivated a-Si:H Back Contacts for Double-Heterojunction Silicon Solar Cells: Preprint

    SciTech Connect

    Page, M. R.; Iwaniczko, E.; Xu, Y.; Wang, Q.; Yan, Y.; Roybal, L.; Branz, H. M.; Wang, T. H.

    2006-05-01

    We have developed hydrogenated amorphous silicon (a Si:H) back contacts to both p- and n-type silicon wafers, and employed them in double-heterojunction solar cells. These contacts are deposited entirely at low temperature (<250 C) and replace the standard diffused or alloyed back-surface-field contacts used in single-heterojunction (front-emitter only) cells. High-quality back contacts require excellent surface passivation, indicated by a low surface recombination velocity of minority-carriers (S) or a high open-circuit voltage (Voc). The back contact must also provide good conduction for majority carriers to the external circuit, as indicated by a high light I-V fill factor. We use hot-wire chemical vapor deposition (HWCVD) to grow a-Si:H layers for both the front emitters and back contacts. Our improved a-Si:H back contacts contribute to our recent achievement of a confirmed 18.2% efficiency in double-heterojunction silicon solar cells on p type textured silicon wafers.

  18. Production of Porous β-Type Ti–40Nb Alloy for Biomedical Applications: Comparison of Selective Laser Melting and Hot Pressing

    PubMed Central

    Zhuravleva, Ksenia; Bönisch, Matthias; Prashanth, Konda Gokuldoss; Hempel, Ute; Helth, Arne; Gemming, Thomas; Calin, Mariana; Scudino, Sergio; Schultz, Ludwig; Eckert, Jürgen; Gebert, Annett

    2013-01-01

    We used selective laser melting (SLM) and hot pressing of mechanically-alloyed β-type Ti–40Nb powder to fabricate macroporous bulk specimens (solid cylinders). The total porosity, compressive strength, and compressive elastic modulus of the SLM-fabricated material were determined as 17% ± 1%, 968 ± 8 MPa, and 33 ± 2 GPa, respectively. The alloy’s elastic modulus is comparable to that of healthy cancellous bone. The comparable results for the hot-pressed material were 3% ± 2%, 1400 ± 19 MPa, and 77 ± 3 GPa. This difference in mechanical properties results from different porosity and phase composition of the two alloys. Both SLM-fabricated and hot-pressed cylinders demonstrated good in vitro biocompatibility. The presented results suggest that the SLM-fabricated alloy may be preferable to the hot-pressed alloy for biomedical applications, such as the manufacture of load-bearing metallic components for total joint replacements. PMID:28788418

  19. Alloy softening in binary molybdenum alloys

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Witzke, W. R.

    1972-01-01

    An investigation was conducted to determine the effects of alloy additions of Hf, Ta, W, Re, Os, Ir, and Pt on the hardness of Mo. Special emphasis was placed on alloy softening in these binary Mo alloys. Results showed that alloy softening was produced by those elements having an excess of s+d electrons compared to Mo, while those elements having an equal number or fewer s+d electrons than Mo failed to produce alloy softening. Alloy softening and hardening can be correlated with the difference in number of s+d electrons of the solute element and Mo.

  20. A Study of Tungsten-Technetium Alloys

    NASA Technical Reports Server (NTRS)

    Maltz, J. W.

    1965-01-01

    Technetium is a sister element to rhenium and has many properties that are similar to rhenium. It is predicted that technetium will have about the same effects on tungsten as rhenium in regard to increase in workability, lowered ductile to brittle transition temperature, and improved ductility. The objectives of the current work are to recover technetium from fission product wastes at Hanford Atomic Products Operation and reduce to purified metal; prepare W-Tc alloys containing up to 50 atomic% Tc; fabricate the alloy ingots to sheet stock, assessing the effect of technetium on workability; and perform metallurgical and mechanical properties evaluation of the fabricated alloys. Previous reports have described the separation and purification of 800 g of technetium metal powder, melting of technetium and W-Tc alloys, and some initial observation of the alloy material.

  1. Study and Simulation of the Heterojunction Thin Film Solar Cell a-Si( n)/a-Si( i)/c-Si( p)/a-Si( i)/a-Si( p)

    NASA Astrophysics Data System (ADS)

    Toufik, Zarede; Hamza, Lidjici; Mohamed, Fathi; Achour, Mahrane

    2016-08-01

    In this article, we present a study based on numerical simulation of the electrical characteristics of a thin-film heterojunction solar cell (a-Si( n)/a-Si( i)/c-Si( p)/a-Si( i)/a-Si( p)), using the automat for simulation of hetero-structures (AFORS-Het) software. This cell is composed of four main layers of silicon (Si): (i) 5 nm amorphous silicon doped n, (ii) 100 μm crystalline silicon (substrate) doped p, (iii) 5 nm amorphous silicon doped p, and (iv) 3 nm amorphous silicon intrinsic. This cell has a front and rear metal contact of aluminum and zinc oxide (ZnO) front layer transparent conductive oxide of 80 nm thickness. The simulations were performed at conditions of "One Sun" irradiation with air mass 1.5 (AM1.5), and under absolute temperature T = 300 K. The simulation results have shown a high electrical conversion efficiency of about 30.29% and high values of open circuit voltage V oc = 779 mV. This study has also shown that the studied cell has good quality light absorption on a very broad spectrum.

  2. Hardfacing with cobalt and nickel alloys

    SciTech Connect

    Wu, J.B.C. ); Redman, J. , Los Angles, CA )

    1994-09-01

    The use of cobalt or nickel alloys for added wear resistance was initiated in the early 1900s with the development of the cobalt-chromium-tungsten family of alloys. The cobalt alloys were called the Stellite'' because of their bright, shiny, nontarnished appearance. Further development and characterization of this alloy system established its usage in unlubricated metal-to-metal contact or erosion by high-velocity fluid or solid particulate impingement. Initially, the alloys were used as solid castings but later were applied by welding to tougher or more ductile substrates, hence the birth of the hardfacing industry. Many of the original Stellite compositions are still in use, but many others, including the nickel and iron alloys, have been developed for special applications or for use by newer application procedures. Examining the microstructural features and wear properties of these families of hardfacing alloys can help in choosing the right alloy for the job. Various cobalt and nickel alloys, their available product forms and the corresponding hardfacing methods, are reviewed in this article.

  3. Corrosion resistance of alumina-forming alloys against molten chlorides for energy production. I: Pre-oxidation treatment and isothermal corrosion tests

    DOE PAGES

    Gomez-Vidal, J. C.; Fernandez, A. G.; Tirawat, R.; ...

    2017-02-24

    Advanced components in next-generation concentrating solar power (CSP) applications will require advanced heat-transfer fluids and thermal-storage materials that work from about 550 °C to at least 720 °C, for integration with advanced power-conversion systems. To reach the cost target, less-expensive salts such as molten chlorides have been identified as high-temperature fluid candidates. High-strength alloys need to be identified and their mechanical and chemical degradation must be minimized to be used in CSP applications. Approaches for corrosion mitigation need to be investigated and optimized to drive down corrosion rates to acceptable levels—in the order of tens of micrometers per year—for achievingmore » a long system lifetime of at least 30 years. Surface passivation is a good corrosion mitigation approach because the alloy could then be exposed to both the liquid and the vapor phases of the salt mixture. In this investigation, we pre-oxidized the alumina-forming alloys Inconel 702, Haynes 224, and Kanthal APMT at different temperatures, dwelling times, and atmospheres to produce the passivation by forming protective oxides at the surface. The pretreated alloys were later corroded in molten MgCl2 – 64.41 wt% KCl at 700 °C in a flowing Ar atmosphere. We performed electrochemical techniques such as open-circuit potential followed by a potentiodynamic polarization sweep and conventional long-term weight-change tests to down-select the best-performing alloy and pre-oxidation conditions. The best corrosion results were obtained for In702 pre-oxidized in zero air at 1050 °C for 4 h. Finally, metallographic characterization of the pre-oxidized alloys and of the corroded surfaces showed that the formation of dense and uniform alumina scale during the pre-oxidation appears to protect the alloy from attack by molten chloride.« less

  4. NASA-427: A New Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Nabors, Sammy A.

    2015-01-01

    NASA's Marshall Space Flight Center researchers have developed a new, stronger aluminum alloy, ideal for cast aluminum products that have powder or paint-baked thermal coatings. With advanced mechanical properties, the NASA-427 alloy shows greater tensile strength and increased ductility, providing substantial improvement in impact toughness. In addition, this alloy improves the thermal coating process by decreasing the time required for heat treatment. With improvements in both strength and processing time, use of the alloy provides reduced materials and production costs, lower product weight, and better product performance. The superior properties of NASA-427 can benefit many industries, including automotive, where it is particularly well-suited for use in aluminum wheels.

  5. Study of fluoride corrosion of nickel alloys

    NASA Technical Reports Server (NTRS)

    Gunther, W. H.; Steindler, M. J.

    1969-01-01

    Report contains the results of an investigation of the corrosion resistance of nickel and nickel alloys exposed to fluorine, uranium hexafluoride, and volatile fission product fluorides at high temperatures. Survey of the unclassified literature on the subject is included.

  6. Influence of base pressure and atmospheric contaminants on a-Si:H solar cell properties

    SciTech Connect

    Woerdenweber, J.; Schmitz, R.; Mueck, A.; Zastrow, U.; Niessen, L.; Gordijn, A.; Carius, R.; Beyer, W.; Rau, U.; Merdzhanova, T.; Stiebig, H.

    2008-11-01

    The influence of atmospheric contaminants oxygen and nitrogen on the performance of thin-film hydrogenated amorphous silicon (a-Si:H) solar cells grown by plasma-enhanced chemical vapor deposition at 13.56 MHz was systematically investigated. The question is addressed as to what degree of high base pressures (up to 10{sup -4} Torr) are compatible with the preparation of good quality amorphous silicon based solar cells. The data show that for the intrinsic a-Si:H absorber layer exists critical oxygen and nitrogen contamination levels (about 2x10{sup 19} atoms/cm{sup 3} and 4x10{sup 18} atoms/cm{sup 3}, respectively). These levels define the minimum impurity concentration that causes a deterioration in solar cell performance. This critical concentration is found to depend little on the applied deposition regime. By enhancing, for example, the flow of process gases, a higher base pressure (and leak rate) can be tolerated before reaching the critical contamination level. The electrical properties of the corresponding films show that increasing oxygen and nitrogen contamination results in an increase in dark conductivity and photoconductivity, while activation energy and photosensitivity are decreased. These effects are attributed to nitrogen and oxygen induced donor states, which cause a shift of the Fermi level toward the conduction band and presumably deteriorate the built-in electric field in the solar cells. Higher doping efficiencies are observed for nitrogen compared to oxygen. Alloying effects (formation of SiO{sub x}) are observed for oxygen contaminations above 10{sup 20} atoms/cm{sup 3}, leading to an increase in the band gap.

  7. Final Assessment of Preindustrial Solid-State Route for High-Performance Mg-System Alloys Production: Concluding the EU Green Metallurgy Project

    NASA Astrophysics Data System (ADS)

    D'Errico, Fabrizio; Plaza, Gerardo Garces; Giger, Franz; Kim, Shae K.

    2013-10-01

    The Green Metallurgy Project, a LIFE+ project co-financed by the European Union Commission, has now been completed. The purpose of the Green Metallurgy Project was to establish and assess a preindustrial process capable of using nanostructured-based high-performance Mg-Zn(Y) magnesium alloys and fully recycled eco-magnesium alloys. In this work, the Consortium presents the final outcome and verification of the completed prototype construction. To compare upstream cradle-to-grave footprints when ternary nanostructured Mg-Y-Zn alloys or recycled eco-magnesium chips are produced during the process cycle using the same equipment, a life cycle analysis was completed following the ISO 14040 methodology. During tests to fine tune the prototype machinery and compare the quality of semifinished bars produced using the scaled up system, the Buhler team produced interesting and significant results. Their tests showed the ternary Mg-Y-Zn magnesium alloys to have a highest specific strength over 6000 series wrought aluminum alloys usually employed in automotive components.

  8. Single-Step Production of Nanostructured Copper-Nickel (CuNi) and Copper-Nickel-Indium (CuNiIn) Alloy Particles

    NASA Astrophysics Data System (ADS)

    Apaydın, Ramazan Oğuzhan; Ebin, Burçak; Gürmen, Sebahattin

    2016-07-01

    Nanostructured copper-nickel (CuNi) and copper-nickel-indium (CuNiIn) alloy particles were produced from aqueous solutions of copper, nickel nitrates and indium sulfate by hydrogen reduction-assisted ultrasonic spray pyrolysis. The effects of reduction temperatures, at 973 K, 1073 K, and 1173 K (700 °C, 800 °C, and 900 °C), on the morphology and crystalline structure of the alloy particles were investigated under the conditions of 0.1 M total precursor concentration and 0.5 L/min H2 volumetric flow rate. X-ray diffraction studies were performed to investigate the crystalline structure. Particle size and morphology were investigated by scanning electron microscope and energy-dispersive spectroscopy was applied to determine the chemical composition of the particles. Spherical nanocrystalline binary CuNi alloy particles were prepared in the particle size range from 74 to 455 nm, while ternary CuNiIn alloy particles were obtained in the particle size range from 80 to 570 nm at different precursor solution concentrations and reduction temperatures. Theoretical and experimental chemical compositions of all the particles are nearly the same. Results reveal that the precursor solution and reduction temperature strongly influence the particle size of the produced alloy particles.

  9. Respiratory manganese particle size, time-course and neurobehavioral outcomes in workers at a manganese alloy production plant.

    PubMed

    Park, Robert M; Bouchard, Maryse F; Baldwin, Mary; Bowler, Rosemarie; Mergler, Donna

    2014-12-01

    The progression of manganism with chronic exposure to airborne manganese (Mn) is not well understood. Here, we further investigate the findings on exposure and neurobehavioral outcomes of workers from a silico- and ferromanganese production plant and non-exposed workers from the same community in 1990 and 2004, using a variety of exposure metrics that distinguish particle size and origin within the range of respirable airborne exposures. Mn exposure matrices for large respirable particulate (Mn-LRP, dust) and small respirable particulate (Mn-SRP, fume), based on process origins, were used together with detailed work histories since 1973 (plant opening), to construct exposure metrics including burdens and cumulative burdens with various clearance half-lives. For three out of eight 1990 neurobehavioral tests analyzed with linear regression models, duration of Mn exposure was the best predictor: Luria-Nebraska Neuropsychological Battery - Motor Scale, Trail-Making B and Finger Tapping. The Luria-Nebraska Motor Scale had the strongest association (t ∼ 5.0, p < 10(-6)). For outcomes on three other tests, the duration and Mn-SRP metrics were comparable: Trail Making Test A, Cancellation H and Stroop Color-Word Test (color/word subtest). Delayed Word Recall was best predicted by Mn-SRP (based on square root or truncated air-concentrations). The Word score on the Stroop Color-Word Test was the only outcome for which Mn-LRP was the leading predictor (t = -2.92, p = 0.003), while performance on the WAIS-R Digit Span Test was not significantly predicted by any metric. For outcomes evaluated in both 1990 and 2004, a mixed-effect linear regression model was used to examine estimates of within-individual trends. Duration and Mn-SRP were associated with performance on the Luria-Nebraska Motor Scale, as well as with other outcomes that appeared to have both reversible and progressive features, including Trail Making A and B, Cancellation H and Delayed Word Recall. With the mixed

  10. Respiratory manganese particle size, time-course and neurobehavioral outcomes in workers at a manganese alloy production plant

    PubMed Central

    Park, Robert M.; Bouchard, Maryse F.; Baldwin, Mary; Bowler, Rosemarie; Mergler, Donna

    2015-01-01

    The progression of manganism with chronic exposure to airborne manganese (Mn) is not well understood. Here, we further investigate the findings on exposure and neurobehavioral outcomes of workers from a silico- and ferromanganese production plant and non-exposed workers from the same community in 1990 and 2004, using a variety of exposure metrics that distinguish particle size and origin within the range of respirable airborne exposures. Mn exposure matrices for large respirable particulate (Mn-LRP, dust) and small respirable particulate (Mn-SRP, fume), based on process origins, were used together with detailed work histories since 1973 (plant opening), to construct exposure metrics including burdens and cumulative burdens with various clearance half-lives. For three out of eight 1990 neurobehavioral tests analyzed with linear regression models, duration of Mn exposure was the best predictor: Luria-Nebraska Neuropsychological Battery – Motor Scale, Trail-Making B and Finger Tapping. The Luria-Nebraska Motor Scale had the strongest association (t ~ 5.0, p < 10−6). For outcomes on three other tests, the duration and Mn-SRP metrics were comparable: Trail Making Test A, Cancellation H and Stroop Color-Word Test (color/word subtest). Delayed Word Recall was best predicted by Mn-SRP (based on square root or truncated air-concentrations). The Word score on the Stroop Color-Word Test was the only outcome for which Mn-LRP was the leading predictor (t = −2.92, p = 0.003), while performance on the WAIS-R Digit Span Test was not significantly predicted by any metric. For outcomes evaluated in both 1990 and 2004, a mixed-effect linear regression model was used to examine estimates of within-individual trends. Duration and Mn-SRP were associated with performance on the Luria-Nebraska Motor Scale, as well as with other outcomes that appeared to have both reversible and progressive features, including Trail Making A and B, Cancellation H and Delayed Word Recall. With the

  11. Systems study of transport aircraft incorporating advanced aluminum alloys

    NASA Technical Reports Server (NTRS)

    Sakata, I. F.

    1982-01-01

    A study was performed to quantify the potential benefits of utilizing advanced aluminum alloys in commercial transport aircraft and to define the effort necessary to develop fully the alloys to a viable commercial production capability. The comprehensive investigation (1) established realistic advanced aluminum alloy property goals to maximize aircraft systems effectiveness (2) identified performance and economic benefits of incorporating the advanced alloy in future advanced technology commercial aircraft designs (3) provided a recommended plan for development and integration of the alloys into commercial aircraft production (4) provided an indication of the timing and investigation required by the metal producing industry to support the projected market and (5) evaluate application of advanced aluminum alloys to other aerospace and transit systems as a secondary objective. The results of the investigation provided a roadmap and identified key issues requiring attention in an advanced aluminum alloy and applications technology development program.

  12. Titanium Alloys and Processing for High Speed Aircraft

    NASA Technical Reports Server (NTRS)

    Brewer, William D.; Bird, R. Keith; Wallace, Terryl A.

    1996-01-01

    Commercially available titanium alloys as well as emerging titanium alloys with limited or no production experience are being considered for a variety of applications to high speed commercial aircraft structures. A number of government and industry programs are underway to improve the performance of promising alloys by chemistry and/or processing modifications and to identify appropriate alloys and processes for specific aircraft structural applications. This paper discusses some of the results on the effects of heat treatment, service temperatures from - 54 C to +177 C, and selected processing on the mechanical properties of several candidate beta and alpha-beta titanium alloys. Included are beta alloys Timetal 21S, LCB, Beta C, Beta CEZ, and Ti-10-2-3 and alpha-beta alloys Ti-62222, Ti-6242S, Timetal 550, Ti-62S, SP-700, and Corona-X. The emphasis is on properties of rolled sheet product form and on the superplastic properties and processing of the materials.

  13. Influence of casting conditions and alloy additives on the Zn40Al2Cu alloy structure

    NASA Astrophysics Data System (ADS)

    Michalik, R.; Tomaszewska, A.; Woźnica, H.

    2011-05-01

    Zn-Al-Cu alloys are characterized by several advantageous properties that can include good castability, good tribological properties, and low energy value needed to form the product. In comparison to bronzes, Zn-Al-Cu alloys are characterized by a lower density. The purpose of this study was to determine the effect of casting conditions and the addition of silicon and rare earth elements on the structure of a Zn-40%Al alloy. The subjects of this examination were an unmodified alloy, an alloy with the addition of 1,5% Si, and an alloy with additions of 1,5%Si and rare earth elements. Samples were cast in sand and graphite molds. In order to determine the microstructure of the tested samples, metallographic examinations using a light microscope and a scanning electron microscope with energy dispersive spectroscopy (EDS) through an X-ray spectrometer were used.

  14. Ultralight amorphous silicon alloy photovoltaic modules for space applications

    NASA Technical Reports Server (NTRS)

    Hanak, J. J.; Chen, Englade; Fulton, C.; Myatt, A.; Woodyard, J. R.

    1987-01-01

    Ultralight and ultrathin, flexible, rollup monolithic PV modules have been developed consisting of multijunction, amorphous silicon alloys for either terrestrial or aerospace applications. The rate of progress in increasing conversion efficiency of stable multijunction and multigap PV cells indicates that arrays of these modules can be available for NASA's high power systems in the 1990's. Because of the extremely light module weight and the highly automated process of manufacture, the monolithic a-Si alloy arrays are expected to be strongly competitive with other systems for use in NASA's space station or in other large aerospace applications.

  15. Metal alloy identifier

    DOEpatents

    Riley, William D.; Brown, Jr., Robert D.

    1987-01-01

    To identify the composition of a metal alloy, sparks generated from the alloy are optically observed and spectrographically analyzed. The spectrographic data, in the form of a full-spectrum plot of intensity versus wavelength, provide the "signature" of the metal alloy. This signature can be compared with similar plots for alloys of known composition to establish the unknown composition by a positive match with a known alloy. An alternative method is to form intensity ratios for pairs of predetermined wavelengths within the observed spectrum and to then compare the values of such ratios with similar values for known alloy compositions, thereby to positively identify the unknown alloy composition.

  16. Alloy 718 for Oilfield Applications

    NASA Astrophysics Data System (ADS)

    deBarbadillo, John J.; Mannan, Sarwan K.

    2012-02-01

    Alloy 718 (UNS N07718) was developed for use in aircraft gas turbine engines, but its unique combination of room-temperature strength and aqueous corrosion resistance made it a candidate for oilfield fasteners, valves, drill tools, and completion equipment. As well environments became more severe, stress corrosion and hydrogen embrittlement failures in production equipment drove the evolution of the composition and microstructure that distinguish today's oilfield-grade 718 from aerospace grades. This paper reviews the development of the grade and its applications and describes some of its unique characteristics, testing, and manufacturing methods as well as newer alloys designed for high-pressure high-temperature (HPHT) conditions.

  17. Production of aluminum-silicon alloy and ferrosilicon and commercial purity aluminum by the direct reduction process. First interim technical report, Phase C for the period 1980 January 1-1980 March 31

    SciTech Connect

    Bruno, M.J.

    1980-10-01

    Pilot reactor VSR-3 was operated with 75 to 120 SCFH O/sub 2/ to supply part of the process heat requirements by combustion of coke. No alloy was made and burden bridging persistently stopped operations. Burning larger coke particles, -3/8 in. +6 mesh, with O/sub 2/ injected through a larger diameter tuyere orifice resulted in oxygen attack on the reactor graphite liner. Updated thermochemical data for Al/sub 2/O/sub 3/ significantly changed the calculated reflux loading for a one-atm blast furnace, predicting almost total reflux and no alloy recovery. Based on these calculations and the experimental problems with combustion heated operation, VSR-3 was modified to study an alternate reduction concept - the blast-arc - which utilizes combustion heat to reduce SiO/sub 2/ to SiC at 1600/sup 0/C, and electrical heat to complete the reduction of Al/sub 2/O/sub 3/ and the production of alloy. Design, fabrication, and installation of most of the pilot crystallizer sytem was completed.

  18. Magnesium-based biodegradable alloys: Degradation, application, and alloying elements

    PubMed Central

    Pogorielov, Maksym; Husak, Eugenia; Solodivnik, Alexandr; Zhdanov, Sergii

    2017-01-01

    In recent years, the paradigm about the metal with improved corrosion resistance for application in surgery and orthopedy was broken. The new class of biodegradable metal emerges as an alternative for biomedical implants. These metals corrode gradually with an appropriate host response and release of corrosion products. And it is absolutely necessary to use essential metals metabolized by hosting organism with local and general nontoxic effect. Magnesium serves this aim best; it plays the essential role in body metabolism and should be completely excreted within a few days after degradation. This review summarizes data from Mg discovery and its first experimental and clinical application of modern concept of Mg alloy development. We focused on biodegradable metal application in general surgery and orthopedic practice and showed the advantages and disadvantages Mg alloys offer. We focused on methods of in vitro and in vivo investigation of degradable Mg alloys and correlation between these methods. Based on the observed data, a better way for new alloy pre-clinical investigation is suggested. This review analyzes possible alloying elements that improve corrosion rate, mechanical properties, and gives the appropriate host response. PMID:28932493

  19. Magnesium-based biodegradable alloys: Degradation, application, and alloying elements.

    PubMed

    Pogorielov, Maksym; Husak, Eugenia; Solodivnik, Alexandr; Zhdanov, Sergii

    2017-03-01

    In recent years, the paradigm about the metal with improved corrosion resistance for application in surgery and orthopedy was broken. The new class of biodegradable metal emerges as an alternative for biomedical implants. These metals corrode gradually with an appropriate host response and release of corrosion products. And it is absolutely necessary to use essential metals metabolized by hosting organism with local and general nontoxic effect. Magnesium serves this aim best; it plays the essential role in body metabolism and should be completely excreted within a few days after degradation. This review summarizes data from Mg discovery and its first experimental and clinical application of modern concept of Mg alloy development. We focused on biodegradable metal application in general surgery and orthopedic practice and showed the advantages and disadvantages Mg alloys offer. We focused on methods of in vitro and in vivo investigation of degradable Mg alloys and correlation between these methods. Based on the observed data, a better way for new alloy pre-clinical investigation is suggested. This review analyzes possible alloying elements that improve corrosion rate, mechanical properties, and gives the appropriate host response.

  20. Stress corrosion in high-strength aluminum alloys

    NASA Technical Reports Server (NTRS)

    Dorward, R. C.; Hasse, K. R.

    1980-01-01

    Report describes results of stress-corrosion tests on aluminum alloys 7075, 7475, 7050, and 7049. Tests compare performance of original stress-corrosion-resistant (SCR) aluminum, 7075, with newer, higher-strength SCR alloys. Alloys 7050 and 7049 are found superior in short-transverse cross-corrosion resistance to older 7075 alloy; all alloys are subject to self-loading effect caused by wedging of corrosion products in cracks. Effect causes cracks to continue to grow, even at very-low externally applied loads.

  1. Nickel alloys in the oral environment.

    PubMed

    Wataha, John C; Drury, Jeanie L; Chung, Whasun O

    2013-07-01

    The use of nickel casting alloys for long-term restorations in dentistry has long been controversial. A 'tug-of-war' between economic, engineering and biological considerations is central to this controversy; nickel-casting alloys have low costs and favorable physical properties, but are corrosion-prone in the oral environment. Clinicians and researchers have questioned the safety of nickel-containing dental alloys because several nickel compounds are known to cause adverse biological effects in vivo and in vitro in contexts outside of dentistry. The debate revolves around the extent to which corrosion products from oral restorations cause intraoral or systemic biological problems. Current evidence suggests that nickel alloys may be used successfully and safely in dentistry if clinical risks are taken into account. However, these alloys may cause significant clinical problems, primarily allergenic and inflammatory, if the risks are ignored.

  2. Photoemission study of Au on a-Si:H

    NASA Astrophysics Data System (ADS)

    Pi, Tun-Wen; Yang, A.-B.; Olson, C. G.; Lynch, D. W.

    1990-11-01

    We report a high-resolution photoemission study of Au evaporated on rf-sputtered a-Si:H at room temperature. Three regions of coverage can be classified according to the behavior of the valence-band and core-level spectra: an unreacted region with an equivalent thickness of 2 Å, followed by an intermixed Au/a-Si overlayer (~9 Å), and a dual-phase region at higher coverage. Au adatoms are dispersed in the unreacted region. They subsequently cluster in the intermixed region, where they attach to Si atoms that are not hydrogen bonded, suggesting that the intermixed Si is mainly from those that have dangling bonds. In the dual-phase region, two sets of Au 4f core levels evolve with higher binding energy, one from Au intermixed with Si, and the lower one exhibiting pure gold character. The interface eventually ends up with the sequence: a-Si:H(sub.)+(pure Au mixed with intermixed Au/Si)+(vac). This is unlike the case of Au on c-Si, which has a pure gold layer sandwiched by intermixed Au/Si complexes along the surface normal. Traces of silicon atoms on top of composite surfaces appear even at the highest coverage, 205 Å, of the gold deposit. The applicability of the four models previously used for the Au/c-Si interface is also briefly discussed.

  3. Production of aluminum-silicon alloy and ferrosilicon and commercial purity aluminum by the direct reduction process. Second annual technical report for the period 1978 September 1-1979 December 31

    SciTech Connect

    Bruno, M.J.

    1980-10-01

    A new computer program was developed for simultaneously solving heat and mass balance at steady state for a flowing one-dimensional chemical reactor. Bench scale reactor results confirmed that minimum final stage reaction temperature is 1950 to 2000/sup 0/C, depending on the Fe/sub 2/O/sub 3/ concentration in the burden. Additions of Fe/sub 2/O/sub 3/ to the charge produced significant increase in metallic yield. A new bench reactor was designed, built, and operated to facilitate semi-continuous operation, using O/sub 2/ injection to burn coke supporting the burden, resulting in burden movement. Validity of the equipment and test procedures was demonstrated by successfully operating the reactor as an iron blast furnace at 1500/sup 0/C. Bench scale fractional crystallizer runs were continued to determine the impurity effects of Fe up to 6.9% and Ti up to 1.25% on alloy product purity and yield. High initial impurity concentrations resulted in less pure Al-Si product and product yield below 50% due to Al and Si losses as Fe-Si-Al and Ti-Si-Al intermetallics. Long term testing was continued in the large bench scale membrane cell to evaluate woven cloth membrane and other construction materials, operating procedures, and effects of operating parameters on cell performance. Included in the latter were starting alloy composition, current density, anode-cathode spacing, and electrolyte composition.

  4. Application of modern aluminum alloys to aircraft

    NASA Astrophysics Data System (ADS)

    Starke, E. A., Jr.; Staley, J. T.

    Aluminum alloys have been the primary material of choice for structural components of aircraft since about 1930. Although polymer matrix composites are being used extensively in high-performance military aircraft and are being specified for some applications in modern commercial aircraft, aluminum alloys are the overwhelming choice for the fuselage, wing, and supporting structure of commercial airliners and military cargo and transport. Well known performance characteristics, known fabrication costs, design experience, and established manufacturing methods and facilities, are just a few of the reasons for the continued confidence in aluminum alloys that will ensure their use in significant quantities for the rest of this century and likely well into the next one. But most significantly, there have been major advances in aluminum aircraft alloys that continue to keep them in a competitive position. In the early years aluminum alloys were developed by trial and error, but over the past thirty years there have been significant advances in our understanding of the relationships among composition, processing, microstructural characteristics and properties. This knowledge base has led to improvements in properties that are important to aircraft applications. This review covers the performance and property requirements for airframe components in current aircraft and describes aluminum alloys and product forms which meet these requirements. It also discusses the structure/property relationships of aluminum aircraft alloys and describes the background and drivers for the development of modern aluminum alloys to improve performance. Finally, technologies under development for future aircraft are discussed.

  5. Effect of fluorine on the structural and electronic properties of a-Si:H:F

    NASA Astrophysics Data System (ADS)

    Langford, A. A.; Mahan, A. H.; Fleet, M. L.; Bender, J.

    1990-04-01

    The effects of fluorine incorporation on the microstructural and electronic properties of a-Si:H:F with 1-7 at. % F have been systematically studied. Infrared spectra show that as the fluorine content increases, silicon dihydride bonding increases. Density measurements confirm that this is associated with an increase in microvoid content, suggesting that fluorine induces the formation of voids which are lined with SiH2. With the increase in F and SiH2, the photoconductivity of the material decreases over 4 orders of magnitude. A review of the literature shows that the appearance of SiH2 is a universal result of >1 at. % F incorporation by many techniques and is not limited to the present study. Mechanisms by which fluorine can induce structural changes are evaluated. These results are contrasted with the use of fluorinated process gases to deposit microcrystalline films and Si-Ge alloys. This has implications for the incorporation of fluorine in photovoltaic devices.

  6. Superconductivity in Metals and Alloys.

    DTIC Science & Technology

    LEAD(METAL), LIQUEFIED GASES, LOW TEMPERATURE RESEARCH, METAL FILMS, METALLIC SOAPS, NIOBIUM ALLOYS, PHASE STUDIES, RESISTANCE (ELECTRICAL), SAMARIUM...SYNTHESIS, TANTALUM ALLOYS, TIN, TIN ALLOYS, TRANSITION TEMPERATURE, VANADIUM ALLOYS

  7. Electrical conductivity optimization of the Na3AlF6-Al2O3-Sm2O3 molten salts system for Al-Sm intermediate binary alloy production

    NASA Astrophysics Data System (ADS)

    Liao, Chun-fa; Jiao, Yun-fen; Wang, Xu; Cai, Bo-qing; Sun, Qiang-chao; Tang, Hao

    2017-09-01

    Metal Sm has been widely used in making Al-Sm magnet alloy materials. Conventional distillation technology to produce Sm has the disadvantages of low productivity, high costs, and pollution generation. The objective of this study was to develop a molten salt electrolyte system to produce Al-Sm alloy directly, with focus on the electrical conductivity and optimal operating conditions to minimize the energy consumption. The continuously varying cell constant (CVCC) technique was used to measure the conductivity for the Na3AlF6-AlF3-LiF-MgF2-Al2O3-Sm2O3 electrolysis medium in the temperature range from 905 to 1055°C. The temperature ( t) and the addition of Al2O3 ( W(Al2O3)), Sm2O3 ( W(Sm2O3)), and a combination of Al2O3 and Sm2O3 into the basic fluoride system were examined with respect to their effects on the conductivity ( κ) and activation energy. The experimental results showed that the molten electrolyte conductivity increases with increasing temperature ( t) and decreases with the addition of Al2O3 or Sm2O3 or both. We concluded that the optimal operation conditions for Al-Sm intermediate alloy production in the Na3AlF6-AlF3-LiF-MgF2-Al2O3-Sm2O3 system are W(Al2O3) + W(Sm2O3) = 3wt%, W(Al2O3): W(Sm2O3) = 7:3, and a temperature of 965 to 995°C, which results in satisfactory conductivity, low fluoride evaporation losses, and low energy consumption.

  8. Corrosion behavior of stainless steel-zirconium alloy waste forms.

    SciTech Connect

    Abraham, D. P.

    1999-01-13

    Stainless steel-zirconium (SS-Zr) alloys are being considered as waste forms for the disposal of metallic waste generated during the electrometallurgical treatment of spent nuclear fuel. The baseline waste form for spent fuels from the EBR-II reactor is a stainless steel-15 wt.% zirconium (SS-15Zr) alloy. This article briefly reviews the microstructure of various SS-Zr waste form alloys and presents results of immersion corrosion and electrochemical corrosion tests performed on these alloys. The electrochemical tests show that the corrosion behavior of SS-Zr alloys is comparable to those of other alloys being considered for the Yucca Mountain geologic repository. The immersion tests demonstrate that the SS-Zr alloys are resistant to selective leaching of fission product elements and, hence, suitable as candidates for high-level nuclear waste forms.

  9. Effects of copper dental alloys on HuT-78 T-cells

    SciTech Connect

    Bumgardner, J.D.; Tilden, A.B.; Lucas, L.C. )

    1991-03-15

    Copper based dental alloys currently being used are known to exhibit high corrosion rates. Canine studies with these Cu alloys reported enhanced levels of Cu ions associated with a chronic inflammatory response in adjacent gingiva. Due to the accumulation of Cu ions in the local gingiva and the potential for adversely affecting cellular immunity, the HuT-78 T-cell line was exposed to the commercial Cu dental alloys, Goldent and Trindium, and a brass alloy for 24 hr. Goldent is a 76%Cu-Al-Zn alloy, and Trindium is a 87% Cu-Al alloy. The brass alloy is based on an alloy no longer commercially available. The commercial Cu alloys decreased viability of the cells by only 20%, while the brass alloy decreased viability of the cells by only 20%, while the brass alloy decreased viability by 67%. All 3 alloys increased the amount of {sup 3}H-thymidine incorporated by the cells by more than 36% as compared to controls. Only the brass alloy caused statistically higher production of IL-2 per number of viable HuT-78 cells as compared to controls. The potential for continued release of Cu and other metallic ions from either Goldent or Trindium raises the concern that these alloys may also reduce cellular viability and elicit higher IL-2 production. Immune function can be altered by changes in cation concentrations. Therefore, if these alloys are used, they have the potential to alter the activity and function of the cellular immune response.

  10. Comparison of Three Primary Surface Recuperator Alloys

    SciTech Connect

    Matthews, Wendy; More, Karren Leslie; Walker, Larry R

    2010-01-01

    Extensive work performed by Capstone Turbine Corporation, Oak Ridge National Laboratory, and various others has shown that the traditional primary surface recuperator alloy, type 347 stainless steel, is unsuitable for applications above 650 C ({approx}1200 F). Numerous studies have shown that the presence of water vapor greatly accelerates the oxidation rate of type 347 stainless steel at temperatures above 650 C ({approx}1200 F). Water vapor is present as a product of combustion in the microturbine exhaust, making it necessary to find replacement alloys for type 347 stainless steel that will meet the long life requirements of microturbine primary surface recuperators. It has been well established over the past few years that alloys with higher chromium and nickel contents than type 347 stainless steel have much greater oxidation resistance in the microturbine environment. One such alloy that has replaced type 347 stainless steel in primary surface recuperators is Haynes Alloy HR-120 (Haynes and HR-120 are trademarks of Haynes International, Inc.), a solid-solution-strengthened alloy with nominally 33 wt % Fe, 37 wt % Ni and 25 wt % Cr. Unfortunately, while HR-120 is significantly more oxidation resistant in the microturbine environment, it is also a much more expensive alloy. In the interest of cost reduction, other candidate primary surface recuperator alloys are being investigated as possible alternatives to type 347 stainless steel. An initial rainbow recuperator test has been performed at Capstone to compare the oxidation resistance of type 347 stainless steel, HR-120, and the Allegheny Ludlum austenitic alloy AL 20-25+Nb (AL 20-25+Nb is a trademark of ATI Properties, Inc. and is licensed to Allegheny Ludlum Corporation). Evaluation of surface oxide scale formation and associated alloy depletion and other compositional changes has been carried out at Oak Ridge National Laboratory. The results of this initial rainbow test will be presented and discussed in this

  11. Thermal stability of interconnected a-Si:H solar modules

    NASA Astrophysics Data System (ADS)

    Willing, F.; Bennett, M.; Newton, J.

    Interconnected solar modules with cell structures of glass/transparent-conducting-oxide (TCO)/piNa-Si/aluminum were heat-treated at a series of elevated temperatures in order to accelerate two degradation modes: interdiffusion at the aluminum/a-Si back contact, and conductivity loss at the aluminum/TCO contacts which serve as connections between individual cells in a module. Plots of device lifetime vs. 1/T extrapolated to normal operating temperatures showed that neither degradation mode would significantly effect module stability over the projected lifetime of the device.

  12. Palladium and its alloys as membrane catalysts

    SciTech Connect

    Gryaznov, V.M.

    1983-05-01

    Possibilities have been examined for the use of selective transport of hydrogen through palladium alloy membranes in order to increase the efficiency of hydrogen recovery from gas mixtures and catalytic reactions in which hydrogen is consumed or formed. By varying the hydrogen concentration in the bulk and on the surface of a palladium alloy, it becomes possible to increase the selectivity of hydrogenation reactions. Continuous and semicontinuous methods have been developed for obtaining valuable products on membrane catalysts.

  13. Coagulated silica - a-SiO2 admixture in cement paste

    NASA Astrophysics Data System (ADS)

    Pokorný, Jaroslav; Pavlíková, Milena; Záleská, Martina; Rovnaníková, Pavla; Pavlík, Zbyšek

    2016-07-01

    Amorphous silica (a-SiO2) in fine-grained form possesses a high pozzolanic activity which makes it a valuable component of blended binders in concrete production. The origin of a-SiO2 applied in cement-based composites is very diverse. SiO2 in amorphous form is present in various amounts in quite a few supplementary cementing materials (SCMs) being used as partial replacement of Portland cement. In this work, the applicability of a commercially produced coagulated silica powder as a partial replacement of Portland cement in cement paste mix design is investigated. Portland cement CEM I 42.5R produced according to the EU standard EN 197-1 is used as a reference binder. Coagulated silica is applied in dosages of 5 and 10 % by mass of cement. The water/binder ratio is kept constant in all the studied pastes. For the applied silica, specific surface area, density, loss on ignition, pozzolanic activity, chemical composition, and SiO2 amorphous phase content are determined. For the developed pastes on the basis of cement-silica blended binder, basic physical properties as bulk density, matrix density, and total open porosity are accessed. Pore size distribution is determined using MIP analysis. Initial and final setting times of fresh mixtures are measured by automatic Vicat apparatus. Effect of silica admixture on mechanical resistivity is evaluated using compressive strength, bending strength, and dynamic Young's modulus measurement. The obtained data gives evidence of a decreased workability of paste mixtures with silica, whereas the setting process is accelerated. On the other hand, reaction activity of silica with Portland cement minerals results in a slight decrease of porosity and improvement of mechanical resistivity of cement pastes containing a-SiO2.

  14. Research of annealing mode for high accuracy stamped parts production from titanium alloy 83Ti-5Al-5Cr-5Mo after tooling

    NASA Astrophysics Data System (ADS)

    Balaykin, A. V.; Nosova, E. A.; Galkina, N. V.

    2016-11-01

    The aim of the work is to solve question of accuracy increase in tolled and annealed parts made from forged rod of titanium alloy. Plate pieces were cut from cross-section, annealed at 800°C during 1, 2, 3, 4 and 5 hours. The criterion combining minimum bending radius and spring back angle was found. This criterion shows the maximum values after tooling and annealing for 3 hours.

  15. Antibacterial biodegradable Mg-Ag alloys.

    PubMed

    Tie, D; Feyerabend, F; Müller, W D; Schade, R; Liefeith, K; Kainer, K U; Willumeit, R

    2013-06-16

    The use of magnesium alloys as degradable metals for biomedical applications is a topic of ongoing research and the demand for multifunctional materials is increasing. Hence, binary Mg-Ag alloys were designed as implant materials to combine the favourable properties of magnesium with the well-known antibacterial property of silver. In this study, three Mg-Ag alloys, Mg2Ag, Mg4Ag and Mg6Ag that contain 1.87 %, 3.82 % and 6.00 % silver by weight, respectively, were cast and processed with solution (T4) and aging (T6) heat treatment. The metallurgical analysis and phase identification showed that all alloys contained Mg4Ag as the dominant β phase. After heat treatment, the mechanical properties of all Mg-Ag alloys were significantly improved and the corrosion rate was also significantly reduced, due to presence of silver. Mg(OH)₂ and MgO present the main magnesium corrosion products, while AgCl was found as the corresponding primary silver corrosion product. Immersion tests, under cell culture conditions, demonstrated that the silver content did not significantly shift the pH and magnesium ion release. In vitro tests, with both primary osteoblasts and cell lines (MG63, RAW 264.7), revealed that Mg-Ag alloys show negligible cytotoxicity and sound cytocompatibility. Antibacterial assays, performed in a dynamic bioreactor system, proved that the alloys reduce the viability of two common pathogenic bacteria, Staphylococcus aureus (DSMZ 20231) and Staphylococcus epidermidis (DSMZ 3269), and the results showed that the killing rate of the alloys against tested bacteria exceeded 90%. In summary, biodegradable Mg-Ag alloys are cytocompatible materials with adjustable mechanical and corrosion properties and show promising antibacterial activity, which indicates their potential as antibacterial biodegradable implant materials.

  16. Hydrogen storage systems from waste Mg alloys

    NASA Astrophysics Data System (ADS)

    Pistidda, C.; Bergemann, N.; Wurr, J.; Rzeszutek, A.; Møller, K. T.; Hansen, B. R. S.; Garroni, S.; Horstmann, C.; Milanese, C.; Girella, A.; Metz, O.; Taube, K.; Jensen, T. R.; Thomas, D.; Liermann, H. P.; Klassen, T.; Dornheim, M.

    2014-12-01

    The production cost of materials for hydrogen storage is one of the major issues to be addressed in order to consider them suitable for large scale applications. In the last decades several authors reported on the hydrogen sorption properties of Mg and Mg-based systems. In this work magnesium industrial wastes of AZ91 alloy and Mg-10 wt.% Gd alloy are used for the production of hydrogen storage materials. The hydrogen sorption properties of the alloys were investigated by means of volumetric technique, in situ synchrotron radiation powder X-ray diffraction (SR-PXD) and calorimetric methods. The measured reversible hydrogen storage capacity for the alloys AZ91 and Mg-10 wt.% Gd are 4.2 and 5.8 wt.%, respectively. For the Mg-10 wt.% Gd alloy, the hydrogenated product was also successfully used as starting reactant for the synthesis of Mg(NH2)2 and as MgH2 substitute in the Reactive Hydride Composite (RHC) 2LiBH4 + MgH2. The results of this work demonstrate the concrete possibility to use Mg alloy wastes for hydrogen storage purposes.

  17. Nickel-base alloys for severe environments

    SciTech Connect

    Wilson, R.K.; Flower, H.L.; Hack, G.A.J.; Isobe, S.

    1996-03-01

    Inconel alloys MA754 and MA758 are nickel-base, oxide dispersion-strengthened superalloys made by mechanical alloying. The simple nickel-chromium matrix, when combined with the strengthening effect of the yttrium oxide dispersoid during mechanical alloys, provides excellent creep properties, resistance to thermal fatigue, and surface stability suitable for operation without protective coatings. Gas turbine engine components are primary applications for alloy MA754, but this aerospace alloy has been applied in many other products that operate in severe conditions, and alloy MA758 was developed specifically for aggressive, elevated temperature industrial environments. Billets for large bar and plate are typically consolidated by hot isostatic pressing (HIP), because this technology allows production of forms suitable for a variety of industrial components. Material consolidated by HIP and conventionally worked by extrusion and hot rolling generally exhibits properties that are more isotropic than those of material consolidated by extrusion. However, the degree of anisotropy depends strongly on the specific processing of the consolidated billet. This article describes production of new mill shapes from HIP billets, and reviews current and potential applications such as skid rails for high-temperature walking-beam furnaces, heat treating furnace parts, equipment for handling molten glass, and furnace tubes.

  18. Advanced Cast Aluminum Alloys

    DTIC Science & Technology

    2009-02-01

    microstructure of the Al - Zn -Mg- Cu alloys was similar to the as-cast microstructure ...Further, new research has been initiated on ultra-high strength, microalloyed Al - Zn -Mg- Cu alloys with the goal of producing complex castings with...wrought 2519 alloy . Further, new research has been initiated on ultra-high strength, microalloyed Al - Zn -Mg- Cu alloys with the goal of producing

  19. Brillouin spectroscopy of progressively annealed amorphous a-Si:H/a-SiC_x:H finite-stage superlattices

    NASA Astrophysics Data System (ADS)

    Xia, Hua; Zhang, X.-K.; Chen, K.-J.; Zhang, Wei; Li, Z.-F.; Feng, Duan

    1996-03-01

    Changes in the elastic properties up to an anneal temperature (T_a) of 800 ^circC of amorphous a-Si:H/a-SiC_x:H finite-stage quasiperiodic superlattices (FQSLs) have been measured by Brillouin light-scattering. At room temperature phase velocity of surface acoustic Rayleigh wave is found to decrease with increasing Fibonacci stage number from j=7 to j=12. Modifications in the structure due to annealing are found at two thresholds. When T_a= 300 ^circC shear modulus c_44 of the superlatrtices starts to increase while the hydrogen atoms begin to evaporate from the structure. This modulus is enhanced by 20% for a 7th-stage FQSL but up to 48% for a 12th-stage FQSL at crystallization temperature T_c=540 ^circC at which temperature the hydrogen is fully evaporated from the sample. However, no difference in the Tc is found for both the superlattices with different stages and the a-Si:H sample. Futher annealing of the superlattices reveals rapidly interlayer two-dimensional grwoth of nanocrystals in strain-free high-order FQSLs which leads to a gradient variation of 5.25×10-2 GPa/^circC in the c_44. Retarded crystallization effect occurring in the low-stage FQSLs is found and attributed to structural and elastic strain related effects. Futhermore, a detailed theoretical model in terms of an effective medium approximation is developed and compared with above results.

  20. SUPERCONDUCTING VANADIUM BASE ALLOY

    DOEpatents

    Cleary, H.J.

    1958-10-21

    A new vanadium-base alloy which possesses remarkable superconducting properties is presented. The alloy consists of approximately one atomic percent of palladium, the balance being vanadium. The alloy is stated to be useful in a cryotron in digital computer circuits.

  1. PLUTONIUM-THORIUM ALLOYS

    DOEpatents

    Schonfeld, F.W.

    1959-09-15

    New plutonium-base binary alloys useful as liquid reactor fuel are described. The alloys consist of 50 to 98 at.% thorium with the remainder plutonium. The stated advantages of these alloys over unalloyed plutonium for reactor fuel use are easy fabrication, phase stability, and the accompanying advantuge of providing a means for converting Th/sup 232/ into U/sup 233/.

  2. DELTA PHASE PLUTONIUM ALLOYS

    DOEpatents

    Cramer, E.M.; Ellinger, F.H.; Land. C.C.

    1960-03-22

    Delta-phase plutonium alloys were developed suitable for use as reactor fuels. The alloys consist of from 1 to 4 at.% zinc and the balance plutonium. The alloys have good neutronic, corrosion, and fabrication characteristics snd possess good dimensional characteristics throughout an operating temperature range from 300 to 490 deg C.

  3. Weldability of intermetallic alloys

    SciTech Connect

    David, S.A. )

    1990-01-01

    Ordered intermetallic alloys are a unique class of material that have potential for structural applications at elevated temperatures. The paper describes the welding and weldability of these alloys. The alloys studied were nickel aluminide (Ni[sub 3]Al), titanium aluminide (Ti[sub 3]Al), and iron aluminide.

  4. Separation in Binary Alloys

    NASA Technical Reports Server (NTRS)

    Frazier, D. O.; Facemire, B. R.; Kaukler, W. F.; Witherow, W. K.; Fanning, U.

    1986-01-01

    Studies of monotectic alloys and alloy analogs reviewed. Report surveys research on liquid/liquid and solid/liquid separation in binary monotectic alloys. Emphasizes separation processes in low gravity, such as in outer space or in free fall in drop towers. Advances in methods of controlling separation in experiments highlighted.

  5. Structural alloys for high field superconducting magnets

    SciTech Connect

    Morris, J.W. Jr.

    1985-08-01

    Research toward structural alloys for use in high field superconducting magnets is international in scope, and has three principal objectives: the selection or development of suitable structural alloys for the magnet support structure, the identification of mechanical phenomena and failure modes that may influence service behavior, and the design of suitable testing procedures to provide engineering design data. This paper reviews recent progress toward the first two of these objectives. The structural alloy needs depend on the magnet design and superconductor type and differ between magnets that use monolithic and those that employ force-cooled or ICCS conductors. In the former case the central requirement is for high strength, high toughness, weldable alloys that are used in thick sections for the magnet case. In the latter case the need is for high strength, high toughness alloys that are used in thin welded sections for the conductor conduit. There is productive current research on both alloy types. The service behavior of these alloys is influenced by mechanical phenomena that are peculiar to the magnet environment, including cryogenic fatigue, magnetic effects, and cryogenic creep. The design of appropriate mechanical tests is complicated by the need for testing at 4/sup 0/K and by rate effects associated with adiabatic heating during the tests. 46 refs.

  6. Electrical and optical properties of hydrogenated amorphous silicon-germanium (a-Si1 - xGexH) films prepared by reactive ion beam sputtering

    NASA Astrophysics Data System (ADS)

    Bhan, Mohan Krishan; Malhotra, L. K.; Kashyap, Subhash C.

    1989-09-01

    Thin films of hydrogenated amorphous silicon-germanium (a-Si1-xGex: H) alloys have been prepared by reactive ion beam sputtering of a composite target of silicon and germanium. The dependence of the deposition rate, conductivity-temperature variation, optical absorption coefficient, refractive index, imaginary part of the dielectric constant, hydrogen content, and infrared (IR) absorption spectra on germanium content (x) are reported and analyzed. For a typical composition—a-Si28Ge72:H (x=0.72), the effect of beam voltage, H2:Ar flow ratio, and substrate temperature on the material properties have also been investigated. For the films prepared with increasing x, the expected behavior of a decrease in both hydrogen content and band gap and an increase in the electrical conductivity have been observed. The films prepared at x>0.80 are found to be more homogeneous than the films deposited at 0.0a-Si1-xGex: H network in the latter case. The a-Si28Ge72:H films exhibiting minimum conductivity (1.7×10-7 Ω-1 cm-1) have been obtained for an H2:Ar flow ratio of 10:1 and a beam voltage and substrate temperature of 1500 V and 300 °C, respectively. These films contain a hydrogen concentration of 10.2 at. % and show an optical band gap of 1.25 eV. The IR studies have shown that a-Si28Ge72:H films prepared both at low beam voltages and at low substrate temperatures show the unusual preferential attachment of hydrogen to Ge rather than to Si.

  7. Rhenium alloying of tungsten heavy alloys

    SciTech Connect

    German, R.M.; Bose, A.; Jerman, G.

    1989-01-01

    Alloying experiments were performed using rhenium additions to a classic 90 mass % tungsten heavy alloy. The mixed-powder system was liquid phase sintered to full density at 1500 C in 60 min The rhenium-modified alloys exhibited a smaller grain size, higher hardness, higher strength, and lower ductility than the unalloyed system. For an alloy with a composition of 84W-6Re-8Ni-2Fe, the sintered density was 17, 4 Mg/m{sup 3} with a yield strength of 815 MPa, tensile strength of 1180 MPa, and elongation to failure of 13%. This property combination results from the aggregate effects of grain size reduction and solid solution hardening due to rhenium. In the unalloyed system these properties require post-sintering swaging and aging; thus, alloying with rhenium is most attractive for applications where net shaping is desired, such as by powder injection molding.

  8. Hydrogenated amorphous silicon oxide (a-SiOx:H) single junction solar cell with 8.8% initial efficiency by reducing parasitic absorptions

    NASA Astrophysics Data System (ADS)

    Kim, Do Yun; Guijt, Erwin; van Swaaij, René A. C. M. M.; Zeman, Miro

    2017-04-01

    Hydrogenated amorphous silicon oxide (a-SiOx:H) solar cells have been successfully implemented to multi-junction thin film silicon solar cells. The efficiency of these solar cells, however, has still been below that of state-of-the-art solar cells mainly due to the low Jsc of the a-SiOx:H solar cells and the unbalanced current matching between sub-cells. In this study, we carry out optical simulations to find the main optical losses for the a-SiOx:H solar cell, which so far was mainly optimized for Voc and fill-factor (FF). It is observed that a large portion of the incident light is absorbed parasitically by the p-a-SiOx:H and n-a-SiOx:H layers, although the use of these layers leads to the highest Voc × FF product. When a more transparent and conductive p-nc-SiOx:H layer is substituted for the p-a-SiOx:H layer, the parasitic absorption loss at short wavelengths is notably reduced, leading to higher Jsc. However, this gain in Jsc by the use of the p-nc-SiOx:H compromises the Voc. When replacing the n-a-SiOx:H layer for an n-nc-SiOx:H layer that has low n and k values, the plasmonic absorption loss at the n-nc-SiOx:H/Ag interfaces and the parasitic absorption in the n-nc-SiOx:H are substantially reduced. Implementation of this n-nc-SiOx:H leads to an increase of the Jsc without a drop of the Voc and FF. When implementing a thinner p-a-SiOx:H layer, a thicker i-a-SiOx:H layer, and an n-nc-SiOx:H layer, a-SiOx:H solar cells with not only high Jsc but also high Voc and FF can be fabricated. As a result, an 8.8% a-SiOx:H single junction solar cell is successfully fabricated with a Voc of 1.02 V, a FF of 0.70, and a Jsc of 12.3 mA/cm2, which is the highest efficiency ever reported for this type of solar cell.

  9. Processing and alloying of tungsten heavy alloys

    SciTech Connect

    Bose, A.; Dowding, R.J.

    1993-12-31

    Tungsten heavy alloys are two-phase metal matrix composites with a unique combination of density, strength, and ductility. They are processed by liquid-phase sintering of mixed elemental powders. The final microstructure consists of a contiguous network of nearly pure tungsten grains embedded in a matrix of a ductile W-Ni-Fe alloy. Due to the unique property combination of the material, they are used extensively as kinetic energy penetrators, radiation shields. counterbalances, and a number of other applications in the defense industry. The properties of these alloys are extremely sensitive to the processing conditions. Porosity levels as low as 1% can drastically degrade the properties of these alloys. During processing, care must be taken to reduce or prevent incomplete densification, hydrogen embrittlement, impurity segregation to the grain boundaries, solidification shrinkage induced porosity, and in situ formation of pores due to the sintering atmosphere. This paper will discuss some of the key processing issues for obtaining tungsten heavy alloys with good properties. High strength tungsten heavy alloys are usually fabricated by swaging and aging the conventional as-sintered material. The influence of this on the shear localization tendency of a W-Ni-Co alloy will also be demonstrated. Recent developments have shown that the addition of certain refractory metals partially replacing tungsten can significantly improve the strength of the conventional heavy alloys. This development becomes significant due to the recent interest in near net shaping techniques such as powder injection moldings. The role of suitable alloying additions to the classic W-Ni-Fe based heavy alloys and their processing techniques will also be discussed in this paper.

  10. Effect of Alloying Elements on Nano-ordered Wear Property of Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Yagi, Takahiro; Hirayama, Tomoko; Matsuoka, Takashi; Somekawa, Hidetoshi

    2017-03-01

    The effect of alloying elements on nano-ordered wear properties was investigated using fine-grained pure magnesium and several types of 0.3 at. pct X (X = Ag, Al, Ca, Li, Mn, Y, and Zn) binary alloys. They had an average grain size of 3 to 5 μm and a basal texture due to their production by the extrusion process. The specific wear rate was influenced by the alloying element; the Mg-Ca and Mg-Mn alloys showed the best and worst wear property, respectively, among the present alloying elements, which was the same trend as that for indentation hardness. Deformed microstructural observations revealed no formation of deformation twins, because of the high activation of grain boundary-induced plasticity. On the contrary, according to scratched surface observations, when grain boundary sliding partially contributed to deformation, these alloys had large specific wear rates. These results revealed that the wear property of magnesium alloys was closely related to the plastic deformation mechanism. The prevention of grain boundary sliding is important to improve the wear property, which is the same as that of a large-scale wearing configuration. One of the influential factors is the change in the lattice parameter with the chemical composition, i.e., ∂( c/ a)/∂ C. An alloying element that has a large value of ∂( c/ a)/∂ C effectively enhances the wear property.

  11. Effect of Alloying Elements on Nano-ordered Wear Property of Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Yagi, Takahiro; Hirayama, Tomoko; Matsuoka, Takashi; Somekawa, Hidetoshi

    2016-12-01

    The effect of alloying elements on nano-ordered wear properties was investigated using fine-grained pure magnesium and several types of 0.3 at. pct X (X = Ag, Al, Ca, Li, Mn, Y, and Zn) binary alloys. They had an average grain size of 3 to 5 μm and a basal texture due to their production by the extrusion process. The specific wear rate was influenced by the alloying element; the Mg-Ca and Mg-Mn alloys showed the best and worst wear property, respectively, among the present alloying elements, which was the same trend as that for indentation hardness. Deformed microstructural observations revealed no formation of deformation twins, because of the high activation of grain boundary-induced plasticity. On the contrary, according to scratched surface observations, when grain boundary sliding partially contributed to deformation, these alloys had large specific wear rates. These results revealed that the wear property of magnesium alloys was closely related to the plastic deformation mechanism. The prevention of grain boundary sliding is important to improve the wear property, which is the same as that of a large-scale wearing configuration. One of the influential factors is the change in the lattice parameter with the chemical composition, i.e., ∂(c/a)/∂C. An alloying element that has a large value of ∂(c/a)/∂C effectively enhances the wear property.

  12. Microstructure and magnetic properties of mechanically alloyed FeSiBAlNi (Nb) high entropy alloys

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Zheng, Zhou; Xu, Jing; Wang, Yan

    2014-04-01

    In this paper, the effects of milling duration and composition on the microstructure and magnetic properties of equi-atomic FeSiBAlNi and FeSiBAlNiNb high entropy alloys during mechanical alloying have been investigated using X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, transmission electron microscopy and alternating gradient magnetometry. The amorphous high entropy alloys have been successfully fabricated using the mechanical alloying method. The results show that the Nb addition prolongs the milling time for the formation of the fully FeSiBAlNi amorphous phase and decreases the glass forming ability. However, FeSiBAlNiNb amorphous high entropy alloy has the higher thermal stability and heat resisting properties. Moreover, the as-milled FeSiBAlNi(Nb) powders are soft-magnetic materials indicated by their low coercivity. The saturation magnetization of the as-milled FeSiBAlNi(Nb) powders decreases with prolonging of the milling time and shows the lowest value when the amorphous high entropy alloys are formed. It suggests that the as-milled products with solid solution phases show the better soft-magnetic properties than those with fully amorphous phases. The Nb addition does not improve the soft-magnetic properties of the FeSiBAlNi high entropy alloys. Rather, both amorphous high entropy alloys have similar soft-magnetic properties after a long milling time.

  13. Castability of Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Bowles, A. L.; Han, Q.; Horton, J. A.

    There is intense research effort into the development of high pressure die cast-able creep resistant magnesium alloys. One of the difficulties encountered in magnesium alloy development for creep resistance is that many additions made to improve the creep properties have reportedly resulted in alloys that are difficult to cast. It is therefore important to have an understanding of the effect of alloying elements on the castability. This paper gives a review of the state of the knowledge of the castability of magnesium alloys.

  14. High strength alloys

    DOEpatents

    Maziasz, Phillip James [Oak Ridge, TN; Shingledecker, John Paul [Knoxville, TN; Santella, Michael Leonard [Knoxville, TN; Schneibel, Joachim Hugo [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Vinegar, Harold J [Bellaire, TX; John, Randy Carl [Houston, TX; Kim, Dong Sub [Sugar Land, TX

    2010-08-31

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tubular that is at least partially made from a material containing at least one of the metal alloys.

  15. High strength alloys

    DOEpatents

    Maziasz, Phillip James; Shingledecker, John Paul; Santella, Michael Leonard; Schneibel, Joachim Hugo; Sikka, Vinod Kumar; Vinegar, Harold J.; John, Randy Carl; Kim, Dong Sub

    2012-06-05

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tublar that is at least partially made from a material containing at least one of the metal alloys.

  16. Extrusion of aluminium alloys

    SciTech Connect

    Sheppard, T.

    1999-01-01

    In recent years the importance of extruded alloys has increased due to the decline in copper extrusion, increased use in structural applications, environmental impact and reduced energy consumption. There have also been huge technical advances. This text provides comprehensive coverage of the metallurgical, mathematical and practical features of the process. The contents include: continuum principles; metallurgical features affecting the extrusion of Al-alloys; extrusion processing; homogenization and extrusion conditions for specific alloys; processing of 6XXX alloys; plant utilization; Appendix A: specification of AA alloys and DIN equivalents; Appendix B: chemical compositions; and Appendix C: typical properties.

  17. Production of Palladium-Silver Thin Film Alloys and Measurements of Phase Diagrams of the PALLADIUM(1-X)SILVER(X)HYDROGEN System.

    NASA Astrophysics Data System (ADS)

    Villalobos-Velasco, Jaime

    1988-06-01

    PdAg Alloy thin films of different compositions were fabricated by crosscondensation of two atomic fluxes on temperature controlled quartz crystal substrates. The fluxes were generated by thermal evaporation of pure materials produced by two electron-beam-guns (e-guns). The process took place under clean high vacuum conditions. Film thickness, growth rate and composition were precisely computer-controlled utilizing three quartz crystal mass monitors (QCM) and a combination of shutters. Criteria for quality of the films were accuracy and homogeneity of thickness and alloy composition. Hydrogen pressure and temperature were carefully controlled for the performance of the hydrogen cycling process in order to study the interaction of hydrogen with the metal alloy thin film structures. All process variables were automatically monitored and controlled to eliminate inaccuracies inherent in manual control. Software and hardware were developed for repeatability of the process parameters and variables to ensure reproduction of the evaporation and hydrogen-cycling processes. Phase diagrams consisting of pressure concentration relations from repeated hydrogen cycling processes were measured using the QCM technique. Results on palladium hydride obtained using the volumetric technique were combined with results from the QCM on similar systems for the development of an empirical method to extract the stress effect inherent in the QCM produced by the expansion of the volume of the palladium host lattice upon hydrogen adsorption. As a consequence bulk behavior of the phase diagrams for thin films thicker than 2500 A were predicted. The results describe the evolution of the phase diagrams of palladium thin films as their thicknesses approach bulk. The evolution of features of the phase diagrams as the incorporation of silver in the palladium host structure changes from 0 to 30% is also described. A reduction of the hydrogen solubility of the PdAg structure occurs as the silver

  18. Creep Resistant Zinc Alloy

    SciTech Connect

    Frank E. Goodwin

    2002-12-31

    This report covers the development of Hot Chamber Die Castable Zinc Alloys with High Creep Strengths. This project commenced in 2000, with the primary objective of developing a hot chamber zinc die-casting alloy, capable of satisfactory service at 140 C. The core objectives of the development program were to: (1) fill in missing alloy data areas and develop a more complete empirical model of the influence of alloy composition on creep strength and other selected properties, and (2) based on the results from this model, examine promising alloy composition areas, for further development and for meeting the property combination targets, with the view to designing an optimized alloy composition. The target properties identified by ILZRO for an improved creep resistant zinc die-casting alloy were identified as follows: (1) temperature capability of 1470 C; (2) creep stress of 31 MPa (4500 psi); (3) exposure time of 1000 hours; and (4) maximum creep elongation under these conditions of 1%. The project was broadly divided into three tasks: (1) Task 1--General and Modeling, covering Experimental design of a first batch of alloys, alloy preparation and characterization. (2) Task 2--Refinement and Optimization, covering Experimental design of a second batch of alloys. (3) Task 3--Creep Testing and Technology transfer, covering the finalization of testing and the transfer of technology to the Zinc industry should have at least one improved alloy result from this work.

  19. Welding the four most popular aluminum alloys

    SciTech Connect

    Irving, B.

    1994-02-01

    The fact that business is good in aluminum welding is a sure sign that more manufacturers and fabricators are using GMA and GTA welding to build new products out of this lightweight nonferrous metal. Among the most widely specified weldable grades are Alloys 6061, 5083, 5052 and 5454. A rundown on these four alloys, including properties and selected applications, is provided. Any company working with aluminum for the first time needs to know something about these four alloys. Alloys of copper-magnesium-silicon combination, of which 6061 is one, are heat-treatable. The three 5XXX series alloys, on the other hand, are nonheat-treatable. According to P.B. Dickerson, consultant, Lower Burrell, Pa., 5083, because of its high magnesium content, is the easiest of the four alloys to arc weld. Dickerson put the cut-off point in weldability at 3.5% magnesium. To prevent cracking, he added, both 6061 and 5052 require much more filler metal than do the other two alloys. Alloy 6061 consists of 0.25Cu, 0.6Si, 1.0Mg, and 0.20Cr. The main applications for 6061 aluminum are structural, architectural, automotive, railway, marine and pipe. It has good formability, weldability, corrosion resistance and strength. Although the 6XXX series alloys are prone to hot cracking, this condition can be readily overcome by correct choice of joint design and electrode. The most popular temper for 6061 is T6, although the -T651, -T4, and -F temper are also popular. The -T651 temper is like a -T6 temper, only it has received some final stretch hardening. The -T4 temper has been solution heat-treated and quenched. The -F temper is in the as-fabricated condition.

  20. Gamma titanium aluminide alloys

    SciTech Connect

    Yamaguchi, M.; Inui, H.; Kishida, K.; Matsumuro, M.; Shirai, Y.

    1995-08-01

    Extensive progress and improvements have been made in the science and technology of gamma titanium aluminide alloys within the last decade. In particular, the understanding of their microstructural characteristics and property/microstructure relationships has been substantially deepened. Based on these achievements, various engineering two-phase gamma alloys have been developed and their mechanical and chemical properties have been assessed. Aircraft and automotive industries arc pursuing their introduction for various structural components. At the same time, recent basic studies on the mechanical properties of two-phase gamma alloys, in particular with a controlled lamellar structure have provided a considerable amount of fundamental information on the deformation and fracture mechanisms of the two-phase gamma alloys. The results of such basic studies are incorporated in the recent alloy and microstructure design of two-phase gamma alloys. In this paper, such recent advances in the research and development of the two-phase gamma alloys and industrial involvement are summarized.

  1. MBE growth of GaP on a Si substrate

    SciTech Connect

    Sobolev, M. S. Lazarenko, A. A.; Nikitina, E. V.; Pirogov, E. V.; Gudovskikh, A. S.; Egorov, A. Yu.

    2015-04-15

    It is shown that single-crystal GaP buffer layers can be formed on a Si substrate by molecular-beam epitaxy, with the “migration-enhanced epitaxy” procedure applied in the stage in which the nucleating layer is formed. When a GaP layer is produced on a p-type silicon substrate, a p-n junction is created in a natural way between the p-Si substrate and the surface n-Si layer produced by the diffusion of phosphorus into the substrate during the course of the epitaxial growth of GaP. This p-n junction can be used as the first junction of a silicon-based multijunction photovoltaic converter.

  2. Plasmonic nano-antenna a-Si:H solar cell.

    PubMed

    Di Vece, Marcel; Kuang, Yinghuan; van Duren, Stephan N F; Charry, Jamie M; van Dijk, Lourens; Schropp, Ruud E I

    2012-12-03

    In this work the effects of plasmonics, nano-focusing, and orthogonalization of carrier and photon pathways are simultaneously explored by measuring the photocurrents in an elongated nano-scale solar cell with a silver nanoneedle inside. The silver nanoneedles formed the support of a conformally grown hydrogenated amorphous silicon (a-Si:H) n-i-p junction around it. A spherical morphology of the solar cell functions as a nano-lens, focusing incoming light directly on the silver nanoneedle. We found that plasmonics, geometric optics, and Fresnel reflections affect the nanostructured solar cell performance, depending strongly on light incidence angle and polarization. This provides valuable insight in solar cell processes in which novel concepts such as plasmonics, elongated nanostructures, and nano-lenses are used.

  3. Use of a Si(Li) detector as β spectrometer.

    PubMed

    Dryák, P; Kovář, P

    2014-05-01

    The aim of this work is to demonstrate the capability of a Si(Li) detector for the measurement of β spectra, despite the energy absorption in air and in the Be window. A simple source holder fixes the source on the symmetry axis at 3mm from the detector window. The β-sources are produced by evaporation on a plastic backing plate. Absorbing materials between the source and the sensitive volume of the detector are 3 mm of air, a Be window, 0.1 μm Si and 20 nm of gold. A model of the detector was created for β spectra simulation using the MCNP 4A code. Experimental spectra of (14)C, (147)Pm, (204)Tl, (90)Sr/(90)Y were compared with simulated spectra.

  4. Hydrogenated Amorphous Silicon (a-Si:H) Colloids

    SciTech Connect

    Harris, Justin T.; Hueso, Jose L.; Korgel, Brian A.

    2010-12-14

    Colloidal particles of hydrogenated amorphous silicon (a-Si:H) were synthesized by decomposition of trisilane (Si{sub 3}H{sub 8}) in supercritical n-hexane (sc-hexane) at temperatures ranging from 380 to 550 °C. The reaction temperature, pressure and Si{sub 3}H{sub 8} concentration have a significant influence on the average particle size, Si bond order and hydrogen content. The particle diameter could be varied from 170 nm to 1.7 μm, with hydrogen loadings between 10% and 58%. Raman spectroscopy of the particles revealed significant differences in Si bond order that correlated with hydrogen content, with the lowest reaction temperatures yielding particles with the least structural order and most associated hydrogen. Particles synthesized at temperatures higher than 420 °C had sufficient bond order to allow crystallization under the Raman laser probe.

  5. Oxidation and volatilization of a niobium alloy

    SciTech Connect

    Smolik, G.R.; McCarthy, K.A.

    1992-07-01

    This report presents the findings from a preliminary investigation into oxidation and volatilization characteristics of a niobium alloy. Niobium is a candidate alloy for use in plasma facing components (PFCS) in experimental fusion reactors like the Intemational Thermonuclear Experimental Reactor (ITER). An experimental alloy was tailored to simulate small changes in chemistry which could result from transmutations from irradiation. The alloy was exposed in air and steam between 800[degree]C and 1200[degree]C. Volatilized products and hydrogen were collected and measured. Post-test examinations were also performed on the samples to determine the amount of material loss during the exposures. The obtained measurements of volatilization flux (g/m[sup 2]-s), hydrogen generation rates (liters/m[sup 2]-s), and recession rates (mm/s) are data which can be used for safety analyses and material performance to predict consequences which may result from an accident involving the ingress of air or steam into the plasma chamber of fusion reactor. In our volatility tests, only molybdenum and niobium were found at release levels above the detection limit. Although molybdenum is present at only 0.12 wt%, the quantities of this element volatilized in air are nearly comparable to the quantities of niobium released. The niobium release in steam is only three to four times higher than that of molybdenum in steam. The hydrogen production of the niobium alloy is compared with other PFC materials that we have tested, specifically, beryllium, graphite, and a tunesten alloy. At high temperatures, the hydrogen production rate of the niobium alloy is among the lowest of these materials, significantly lower than beryllium. To understand what this means in an accident situation, modeling is necessary to predict temperatures, and therefore total hydrogen production. The INEL is currently doing this modeling.

  6. Production of semi-solid feedstock of A356 alloy and A356-5TiB2 in-situ composite by cooling slope casting

    NASA Astrophysics Data System (ADS)

    Kumar, S. Deepak; Acharya, Mihira; Mandal, A.; Chakraborty, M.

    2015-02-01

    Cooling Slope casting process has gained significant importance for manufacturing of semi-solid feedstock Al alloys and composites which find applications in automotive and aerospace industries. The primary objective of this research is to generate the semi-solid feedstock suitable for thixoforming process. The current work discusses the phenomena involved in the evolution of microstructure of the semi-solid feed stock by Cooling Slope casting process and the effect of various parameters. The process parameters like the angle and length of inclined plate affect the size and morphology of α-Al phase. The Cooling slope process resulted in the formation of fine grain size of about 38 μm of α-Al phase, compared to that of 98 μm processed conventionally. Further, the pouring temperature played a crucial role in the generation of semi-solid microstructures in case of both the alloy and composites. Moreover, fine TiB2 particles of size 0.2-0.5 μm are uniformly distributed in the almost spherical α-Al grains and at the grain boundaries in the composite feed stock. Cooling slope casting route is a suitable and economical route for semi-solid slurry generation by effectively varying the process parameters.

  7. Controlling quality of ferroalloys and alloying additives in the manufacture of nickel alloys for nuclear applications

    SciTech Connect

    Stryker, R.S.

    1981-01-01

    Nickel alloys supplied to the nuclear industry must meet strict requirements for quality and traceability of constituents. Ensuring that end products meet those requirements involves careful control of the raw materials used in melting the alloys. Especially important is an effective system of quality control for purchasing and consuming ferroalloys and alloying additives. Development and operation of such a system requires (1) adequate specifications, (2) good relations with suppliers, (3) an approved-suppliers list, (4) formal receiving inspection, and (5) backup surveillance during processing.

  8. 77 FR 19711 - Certain Seamless Carbon and Alloy Steel Standard, Line, and Pressure Pipe From Germany...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-02

    ... COMMISSION Certain Seamless Carbon and Alloy Steel Standard, Line, and Pressure Pipe From Germany... revocation of the antidumping duty order on certain seamless carbon and alloy steel standard, line, and... Commission found one Domestic Like Product consisting of seamless carbon and alloy steel standard,...

  9. Alloy 10: A 1300F Disk Alloy

    NASA Technical Reports Server (NTRS)

    Gayda, John

    2000-01-01

    Gas turbine engines for future subsonic transports will probably have higher pressure ratios which will require nickel-base superalloy disks with 13000 to 1400 F temperature capability. Several advanced disk alloys are being developed to fill this need. One of these, Allied Signal's Alloy 10, is a promising candidate for gas turbine engines to be used on smaller, regional aircraft. For this application, compressor/turbine disks must withstand temperatures of 1300 F for several hundred hours over the life of the engine. In this paper, three key properties of Alloy 10--tensile, 0.2% creep, and fatigue crack growth--will be assessed at 1300 F.

  10. Light-induced changes in photocarrier transport in magnetron sputtered a-Si:H

    NASA Astrophysics Data System (ADS)

    Doyle, J. R.; Maley, N.; Abelson, J. R.

    1991-08-01

    The effect of light soaking on the steady-state reverse bias collection efficiency has been studied for hydrogenated amorphous silicon films produced by reactive magnetron sputtering. Films with optical gaps of 1.63 and 1.74 eV both showed considerable degradation in the collection efficiency, correlating with increases in sub-gap absorption and decreases in the spectral response quantum efficiency. The collection efficiency data have been fitted with the two-field Hecht expression, and effective mobility-life-time products have been extracted. These results indicate that straightforward measurements on Schottky barriers can be utilized as sensitive monitors of light induced degradation in a-Si:H

  11. Shape memory alloys: New materials for future engineering

    NASA Technical Reports Server (NTRS)

    Hornbogen, E.

    1988-01-01

    Shape memory is a new material property. An alloy which experiences relative severe plastic deformation resumes its original shape again after heating by 10 to 100 C. Besides simple shape memory, in similar alloys there is the second effect where the change in shape is caused exclusively by little temperature change. In pseudo-elasticity, the alloy exhibits a rubber-like behavior, i.e., large, reversible deformation at little change in tension. Beta Cu and beta NiTi alloys have been used in practice. The probability is that soon alloys based on Fe will become available. Recently increasing applications for this alloy were found in various areas of technology, even medical technology. A review with 24 references is given, including properties, production, applications and fundamental principles of the shape memory effect.

  12. Scanning tunneling microscopy studies of the surfaces of a-Si:H and a-SiGe:H films

    SciTech Connect

    Gallagher, A.; Ostrom, R.; Tannenbaum, D. )

    1991-06-01

    The report contains a detailed description of the experimental complexities encountered in developing scanning tunneling microscope (STM) probing of atomic structure on the surface of freshly-grown hydrogenated-amorphous semiconductors. It also contains a speculative microscopic film-growth model that explains differences between the disorder in CVD grown a-Ge:H versus a-Si:H films. This model is derived from prior results obtained in the chemical analysis of GeH{sub 4} plasmas, combined with surface reaction and thermodynamic considerations. The neutral radical fragments of silane, disilane and germane dissociation in discharges, which dominate the vapor and film-growth reactions, have been deduced from detailed analysis of prior data and are reported. 4 refs., 7 figs.

  13. Phase transformation and magnetic properties of Nd-Fe-V-Nb alloys prepared by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Cui, B. Z.; Sun, X. K.; Sui, Y. C.; Geng, D. Y.; Zhang, Z. D.

    2002-09-01

    The phase transformation and magnetic properties of the NdFe 11.35- xV xNb 0.65 ( x=0-1.35) alloys prepared by mechanical alloying (MA) have been studied. Phases of 2:17, 1:7 and 1:12 are formed in the as-annealed alloys with x=0, 0.3-0.7 and 1.0-1.35, respectively. With increasing V content in the NdFe 11.35- xV xNb 0.65 ( x=0.3-0.7) alloys, the Curie temperatures of the matrix 1:7 phases monotonically increase. Upon nitrogenation, with increasing V content, the intrinsic coercivity μ0Hc of the nitrided alloys monotonically increases. The increase becomes sharp at x=1.0 due to the formation of a great amount of Nd(Fe, V) 12N δ. The remanence Jr and the maximum magnetic energy product (BH) max of the nitrided alloys monotonically decrease with increasing V content. The 1:12 phases are formed in all the NdFe 11- xNb xV 1 ( x=0, 0.3, 0.65, 1.0) alloys annealed at 850 oC for 20 min. With increasing Nb content, the crystallization of the 1:12 phase is improved and the relative volume fraction of the 1:12 phase tends to be higher. While μ0Hc of the nitrided alloys monotonically increase, and Jr and (BH) max of the nitrided alloys monotonically decrease. With increasing Nb content in the nitrided alloys, the average grain size of α-Fe decrease while the nitrogen content increases.

  14. The recyclability of lead alloys

    SciTech Connect

    Worcester, A.W.; Sankovitch, M.J.

    1997-12-01

    In 1996, the production of battery lead and alloys from the recycle industry was 3 times the Primary lead production in the United States. The Buick Resource Recovery Center of the Doe Run Lead Company at a capacity of 90,000 tons per year is one of 25 plants recycling lead metal in the United States. This plant was commissioned in 1991 and has been running with a 0.30 Lost Time Accident rate per 200,000 hours of work. The paper delineates and ranks the cost of treating various impurities found in lead.

  15. Iron and alloys of iron. [lunar resources

    NASA Technical Reports Server (NTRS)

    Sastri, Sankar

    1992-01-01

    All lunar soil contains iron in the metallic form, mostly as an iron-nickel alloy in concentrations of a few tenths of 1 percent. Some of this free iron can be easily separated by magnetic means. It is estimated that the magnetic separation of 100,000 tons of lunar soil would yield 150-200 tons of iron. Agglutinates contain metallic iron which could be extracted by melting and made into powder metallurgy products. The characteristics and potential uses of the pure-iron and iron-alloy lunar products are discussed. Processes for working iron that might be used in a nonterrestrial facility are also addressed.

  16. [Microbial corrosion of dental alloy].

    PubMed

    Li, Lele; Liu, Li

    2004-10-01

    There is a very complicated electrolytical environment in oral cavity with plenty of microorganisms existing there. Various forms of corrosion would develop when metallic prosthesis functions in mouth. One important corrosive form is microbial corrosion. The metabolic products, including organic acid and inorganic acid, will affect the pH of the surface or interface of metallic prosthesis and make a change in composition of the medium, thus influencing the electron-chemical reaction and promoting the development of corrosion. The problem of develpoment of microbial corrosion on dental alloy in the oral environment lies in the primary condition that the bacteria adhere to the surface of alloy and form a relatively independent environment that promotes corrosion.

  17. Surface alloying of Mg alloys after surface nanocrystallization.

    PubMed

    Zhang, Ming-Xing; Shi, Yi-Nong; Sun, Haiqing; Kelly, Patrick M

    2008-05-01

    Surface nanocrystallization using a surface mechanical attrition treatment effectively activates the surface of magnesium alloys due to the increase in grain boundary diffusion channels. As a result, the temperature of subsequent surface alloying treatment of pure Mg and AZ91 alloy can be reduced from 430 degrees C to 380 degrees C. Thus, it is possible to combine the surface alloying process with the solution treatment for this type of alloy. After surface alloying, the hardness of the alloyed layer is 3 to 4 times higher than that of the substrate and this may significantly improve the wear resistance of magnesium alloys.

  18. Method for Production of Powders

    NASA Technical Reports Server (NTRS)

    Stoltzfus, Joel M. (Inventor); Sircar, Subhasish (Inventor)

    1997-01-01

    Apparatus and method are disclosed for producing oxides of metals and of metal alloys. The metal or alloy is placed in an oxygen atmosphere in a combustion chamber and ignited. Products of the combustion include one or more oxides of the metal or alloy in powdered form. In one embodiment of the invention a feeder is provided whereby material to be oxidized by combustion can be achieved into a combustion chamber continuously. A product remover receives the powder product of the combustion.

  19. Reference Alloy Waste Form Fabrication and Initiation of Reducing Atmosphere and Reductive Additives Study on Alloy Waste Form Fabrication

    SciTech Connect

    S.M. Frank; T.P. O'Holleran; P.A. Hahn

    2011-09-01

    This report describes the fabrication of two reference alloy waste forms, RAW-1(Re) and RAW-(Tc) using an optimized loading and heating method. The composition of the alloy materials was based on a generalized formulation to process various proposed feed streams resulting from the processing of used fuel. Waste elements are introduced into molten steel during alloy fabrication and, upon solidification, become incorporated into durable iron-based intermetallic phases of the alloy waste form. The first alloy ingot contained surrogate (non-radioactive), transition-metal fission products with rhenium acting as a surrogate for technetium. The second alloy ingot contained the same components as the first ingot, but included radioactive Tc-99 instead of rhenium. Understanding technetium behavior in the waste form is of particular importance due the longevity of Tc-99 and its mobility in the biosphere in the oxide form. RAW-1(Re) and RAW-1(Tc) are currently being used as test specimens in the comprehensive testing program investigating the corrosion and radionuclide release mechanisms of the representative alloy waste form. Also described in this report is the experimental plan to study the effects of reducing atmospheres and reducing additives to the alloy material during fabrication in an attempt to maximize the oxide content of waste streams that can be accommodated in the alloy waste form. Activities described in the experimental plan will be performed in FY12. The first aspect of the experimental plan is to study oxide formation on the alloy by introducing O2 impurities in the melt cover gas or from added oxide impurities in the feed materials. Reducing atmospheres will then be introduced to the melt cover gas in an attempt to minimize oxide formation during alloy fabrication. The second phase of the experimental plan is to investigate melting parameters associated with alloy fabrication to allow the separation of slag and alloy components of the melt.

  20. Synthesis of molybdenum disilicide by mechanical alloying

    SciTech Connect

    Schwarz, R.B.; Srinivasan, S.R.; Petrovic, J.J.; Maggiore, C.J.

    1991-01-01

    We have used mechanical alloying (MA), a high-energy ball-milling process, to prepare MoSi{sub 2} and MoSi{sub 2}-based alloys starting from mixtures of the pure elements. This synthesis route has the potential for preparing oxygen-free MoSi{sub 2} and the flexibility for close control of second-phase additions. MA, first developed for producing oxide-dispersions in Ni-based superalloys, takes advantage of the atomic-level mixing accomplished by the intense mechanical working of the alloy constituents. All the alloying reactions during the process occur in the solid-state. This technique is thus well-suited for synthesizing high melting point materials such as MoSi{sub 2}. The product of the MA process is a highly homogeneous and fine-grained powder. Its purity is determined by the purity of the starting materials and possible impurities introduced during processing. However, a careful control of the MA process enables a minimization of the impurities. We also report here the consolidation of the mechanically alloyed powder and the characterization of the MoSi{sub 2} alloys by optical and transmission electron microscopy, x-ray diffraction, and mechanical property measurements. 21 refs., 9 figs.

  1. PLUTONIUM-ZIRCONIUM ALLOYS

    DOEpatents

    Schonfeld, F.W.; Waber, J.T.

    1960-08-30

    A series of nuclear reactor fuel alloys consisting of from about 5 to about 50 at.% zirconium (or higher zirconium alloys such as Zircaloy), balance plutonium, and having the structural composition of a plutonium are described. Zirconium is a satisfactory diluent because it alloys readily with plutonium and has desirable nuclear properties. Additional advantages are corrosion resistance, excellent fabrication propenties, an isotropie structure, and initial softness.

  2. Amorphous metal alloy

    DOEpatents

    Wang, R.; Merz, M.D.

    1980-04-09

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  3. Manufacturing development of low activation vanadium alloys

    SciTech Connect

    Smith, J.P.; Johnson, W.R.; Baxi, C.B.

    1996-10-01

    General Atomics is developing manufacturing methods for vanadium alloys as part of a program to encourage the development of low activation alloys for fusion use. The culmination of the program is the fabrication and installation of a vanadium alloy structure in the DIII-D tokamak as part of the Radiative Divertor modification. Water-cooled vanadium alloy components will comprise a portion of the new upper divertor structure. The first step, procuring the material for this program has been completed. The largest heat of vanadium alloy made to date, 1200 kg of V-4Cr-4Ti, has been produced and is being converted into various product forms. Results of many tests on the material during the manufacturing process are reported. Research into potential fabrication methods has been and continues to be performed along with the assessment of manufacturing processes particularly in the area of joining. Joining of vanadium alloys has been identified as the most critical fabrication issue for their use in the Radiative Divertor Program. Joining processes under evaluation include resistance seam, electrodischarge (stud), friction and electron beam welding. Results of welding tests are reported. Metallography and mechanical tests are used to evaluate the weld samples. The need for a protective atmosphere during different welding processes is also being determined. General Atomics has also designed, manufactured, and will be testing a helium-cooled, high heat flux component to assess the use of helium cooled vanadium alloy components for advanced tokamak systems. The component is made from vanadium alloy tubing, machined to enhance the heat transfer characteristics, and joined to end flanges to allow connection to the helium supply. Results are reported.

  4. Results of a Si/Cdte Compton Telescope

    SciTech Connect

    Oonuki, Kousuke; Tanaka, Takaaki; Watanabe, Shin; Takeda, Shin'ichiro; Nakazawa, Kazuhiro; Mitani, Takefumi; Takahashi, Tadayuki; Tajima, Hiroyasu; Fukazawa, Yasushi; Nomachi, Masaharu; /Sagamihara, Inst. Space Astron. Sci. /Tokyo U. /SLAC /Hiroshima U. /Osaka U.

    2005-09-23

    We have been developing a semiconductor Compton telescope to explore the universe in the energy band from several tens of keV to a few MeV. We use a Si strip and CdTe pixel detector for the Compton telescope to cover an energy range from 60 keV. For energies above several hundred keV, the higher efficiency of CdTe semiconductor in comparison with Si is expected to play an important role as an absorber and a scatterer. In order to demonstrate the spectral and imaging capability of a CdTe-based Compton Telescope, we have developed a Compton telescope consisting of a stack of CdTe pixel detectors as a small scale prototype. With this prototype, we succeeded in reconstructing images and spectra by solving the Compton equation from 122 keV to 662 keV. The energy resolution (FWHM) of reconstructed spectra is 7.3 keV at 511 keV and 3.1 keV at 122 keV, respectively. The angular resolution obtained at 511 keV is measured to be 12.2{sup o}(FWHM).

  5. NICKEL-BASE ALLOY

    DOEpatents

    Inouye, H.; Manly, W.D.; Roche, T.K.

    1960-01-19

    A nickel-base alloy was developed which is particularly useful for the containment of molten fluoride salts in reactors. The alloy is resistant to both salt corrosion and oxidation and may be used at temperatures as high as 1800 deg F. Basically, the alloy consists of 15 to 22 wt.% molybdenum, a small amount of carbon, and 6 to 8 wt.% chromium, the balance being nickel. Up to 4 wt.% of tungsten, tantalum, vanadium, or niobium may be added to strengthen the alloy.

  6. Supersaturated Aluminum Alloy Powders.

    DTIC Science & Technology

    1981-07-15

    shown in Fig. 18 . It .an be clearly seen that most of the iron is concentrated in the precipitates (Fig. 18 ), X-ray mapping immage for the chromium...At 232°C our alloys are comparable to 2� and 2618 in their tensile properties, and except for alloy #1 which at t i temperature has elongation of...demonstrate better yield strength and UTS than the 2219, 2618 and are comparable to the ALCOA alloy. They show however higher ductility than the ALCOA alloy

  7. Signal and noise analysis of a-Si:H radiation detector-amplifier system

    SciTech Connect

    Cho, Gyuseong

    1992-03-01

    Hydrogenated amorphous silicon (a-Si:H) has potential advantages in making radiation detectors for many applications because of its deposition capability on a large-area substrate and its high radiation resistance. Position-sensitive radiation detectors can be made out of a 1d strip or a 2-d pixel array of a Si:H pin diodes. In addition, signal processing electronics can be made by thin-film transistors on the same substrate. The calculated radiation signal, based on a simple charge collection model agreed well with results from various wave length light sources and 1 MeV beta particles on sample diodes. The total noise of the detection system was analyzed into (a) shot noise and (b) 1/f noise from a detector diode, and (c) thermal noise and (d) 1/f noise from the frontend TFT of a charge-sensitive preamplifier. the effective noise charge calculated by convoluting these noise power spectra with the transfer function of a CR-RC shaping amplifier showed a good agreement with the direct measurements of noise charge. The derived equations of signal and noise charge can be used to design an a-Si:H pixel detector amplifier system optimally. Signals from a pixel can be readout using switching TFTs, or diodes. Prototype tests of a double-diode readout scheme showed that the storage time and the readout time are limited by the resistances of the reverse-biased pixel diode and the forward biased switching diodes respectively. A prototype charge-sensitive amplifier was made using poly-Si TFTs to test the feasibility of making pixel-level amplifiers which would be required in small-signal detection. The measured overall gain-bandwidth product was ~400 MHz and the noise charge ~1000 electrons at a 1 μsec shaping time. When the amplifier is connected to a pixel detector of capacitance 0.2 pF, it would give a charge-to-voltage gain of ~0.02 mV/electron with a pulse rise time less than 100 nsec and a dynamic range of 48 dB.

  8. Signal and noise analysis of a-Si:H radiation detector-amplifier system

    SciTech Connect

    Cho, Gyuseong.

    1992-03-01

    Hydrogenated amorphous silicon (a-Si:H) has potential advantages in making radiation detectors for many applications because of its deposition capability on a large-area substrate and its high radiation resistance. Position-sensitive radiation detectors can be made out of a 1d strip or a 2-d pixel array of a Si:H pin diodes. In addition, signal processing electronics can be made by thin-film transistors on the same substrate. The calculated radiation signal, based on a simple charge collection model agreed well with results from various wave length light sources and 1 MeV beta particles on sample diodes. The total noise of the detection system was analyzed into (a) shot noise and (b) 1/f noise from a detector diode, and (c) thermal noise and (d) 1/f noise from the frontend TFT of a charge-sensitive preamplifier. the effective noise charge calculated by convoluting these noise power spectra with the transfer function of a CR-RC shaping amplifier showed a good agreement with the direct measurements of noise charge. The derived equations of signal and noise charge can be used to design an a-Si:H pixel detector amplifier system optimally. Signals from a pixel can be readout using switching TFTs, or diodes. Prototype tests of a double-diode readout scheme showed that the storage time and the readout time are limited by the resistances of the reverse-biased pixel diode and the forward biased switching diodes respectively. A prototype charge-sensitive amplifier was made using poly-Si TFTs to test the feasibility of making pixel-level amplifiers which would be required in small-signal detection. The measured overall gain-bandwidth product was {approximately}400 MHz and the noise charge {approximately}1000 electrons at a 1 {mu}sec shaping time. When the amplifier is connected to a pixel detector of capacitance 0.2 pF, it would give a charge-to-voltage gain of {approximately}0.02 mV/electron with a pulse rise time less than 100 nsec and a dynamic range of 48 dB.

  9. Hydrogen-plasma-induced Rapid, Low-Temperature Crystallization of μm-thick a-Si:H Films

    PubMed Central

    Zhou, H. P.; Xu, M.; Xu, S.; Liu, L. L.; Liu, C. X.; Kwek, L. C.; Xu, L. X.

    2016-01-01

    Being a low-cost, mass-production-compatible route to attain crystalline silicon, post-deposition crystallization of amorphous silicon has received intensive research interest. Here we report a low-temperature (300 °C), rapid (crystallization rate of ~17 nm/min) means of a-Si:H crystallization based on high-density hydrogen plasma. A model integrating the three processes of hydrogen insertion, etching, and diffusion, which jointly determined the hydrogenation depth of the excess hydrogen into the treated micrometer thick a-Si:H, is proposed to elucidate the hydrogenation depth evolution and the crystallization mechanism. The effective temperature deduced from the hydrogen diffusion coefficient is far beyond the substrate temperature of 300 °C, which implies additional driving forces for crystallization, i.e., the chemical annealing/plasma heating and the high plasma sheath electric field. The features of LFICP (low-frequency inductively coupled plasma) and LFICP-grown a-Si:H are also briefly discussed to reveal the underlying mechanism of rapid crystallization at low temperatures. PMID:27600866

  10. Hydrogen-plasma-induced Rapid, Low-Temperature Crystallization of μm-thick a-Si:H Films

    NASA Astrophysics Data System (ADS)

    Zhou, H. P.; Xu, M.; Xu, S.; Liu, L. L.; Liu, C. X.; Kwek, L. C.; Xu, L. X.

    2016-09-01

    Being a low-cost, mass-production-compatible route to attain crystalline silicon, post-deposition crystallization of amorphous silicon has received intensive research interest. Here we report a low-temperature (300 °C), rapid (crystallization rate of ~17 nm/min) means of a-Si:H crystallization based on high-density hydrogen plasma. A model integrating the three processes of hydrogen insertion, etching, and diffusion, which jointly determined the hydrogenation depth of the excess hydrogen into the treated micrometer thick a-Si:H, is proposed to elucidate the hydrogenation depth evolution and the crystallization mechanism. The effective temperature deduced from the hydrogen diffusion coefficient is far beyond the substrate temperature of 300 °C, which implies additional driving forces for crystallization, i.e., the chemical annealing/plasma heating and the high plasma sheath electric field. The features of LFICP (low-frequency inductively coupled plasma) and LFICP-grown a-Si:H are also briefly discussed to reveal the underlying mechanism of rapid crystallization at low temperatures.

  11. Very fast light-induced degradation of a-Si:H/c-Si(100) interfaces

    NASA Astrophysics Data System (ADS)

    de Wolf, Stefaan; Demaurex, Bénédicte; Descoeudres, Antoine; Ballif, Christophe

    2011-06-01

    Light-induced degradation (LID) of crystalline silicon (c-Si) surfaces passivated with hydrogenated amorphous silicon (a-Si:H) is investigated. The initial passivation decays on polished c-Si(100) surfaces on a time scale much faster than usually associated with bulk a-Si:H LID. This phenomenon is absent for the a-Si:H/c-Si(111) interface. We attribute these differences to the allowed reconstructions on the respective surfaces. This may point to a link between the presence of so-called “fast” states and (internal) surface reconstruction in bulk a-Si:H.

  12. Diffusion bonding of Al7075 alloy to titanium aluminum vanadate alloy

    NASA Astrophysics Data System (ADS)

    Alhazaa, Abdulaziz Nasser

    The aluminum alloy (Al7075) and titanium alloy (Ti-6Al-4V) are used in a variety of applications in the aerospace industry. However, the high cost of Ti-6Al-4V alloy has been a major factor which has limited its use and therefore, the ability to join Al7075 alloy to Ti-6Al-4V alloy can provide a product that is less costly, but retains the high strength and light weight properties necessary for the transport industry. However, the large difference in the physical properties between these two alloys prevents the use of conventional joining techniques such as fusion welding to join these dissimilar alloys. Therefore, the diffusion bonding technique was used to join Al7075 alloy to Ti-6Al-4V alloy with the objective of minimizing microstructural changes of the two alloys during the bonding process. In this thesis, solid state and liquid phase bonding processes were undertaken. Solid state bonding was employed without interlayers and was successful at 510°C and 7 MPa. The bond interface showed an absence of the oxides due to the dissolution of oxygen into the titanium solution. Bonds made using copper interlayers at a temperature sufficient enough to form eutectic liquid formation between copper and aluminum were produced. The intermetallics theta(Al2Cu), S(Al2CuMg) and T(Al2Mg3Zn3) were identified at the aluminum interface while Cu3Ti2 intermetallic was identified at the titanium interface. Bonds made using tin based alloys interlayers and copper coatings were successful and gave the highest shear strength. The eutectic formation on the Al7075 alloy was responsible for joint formation at the aluminum interface while the formation of Sn3Ti5 intermetallic was responsible for the joint formation at titanium interface. The corrosion rate of the bonds decreased with increasing bonding time for joints made using the tin based interlayer in 3% NaCl solution. However, the presence of copper within the joint increased the corrosion rate of the bonds and this was attributed to

  13. Noble metal alloys for metal-ceramic restorations.

    PubMed

    Anusavice, K J

    1985-10-01

    A review of the comparative characteristics and properties of noble metal alloys used for metal-ceramic restorations has been presented. Selection of an alloy for one's practice should be based on long-term clinical data, physical properties, esthetic potential, and laboratory data on metal-ceramic bond strength and thermal compatibility with commercial dental porcelains. Although gold-based alloys, such as the Au-Pt-Pd, Au-Pd-Ag, and Au-Pd classes, may appear to be costly compared with the palladium-based alloys, they have clearly established their clinical integrity and acceptability over an extended period of time. Other than the relatively low sag resistance of the high gold-low silver content alloys and the potential thermal incompatibility with some commercial porcelain products, few clinical failures have been observed. The palladium-based alloys are less costly than the gold-based alloys. Palladium-silver alloys require extra precautions to minimize porcelain discoloration. Palladium-copper and palladium-cobalt alloys may also cause porcelain discoloration, as copper and cobalt are used as colorants in glasses. The palladium-cobalt alloys are least susceptible to high-temperature creep compared with all classes of noble metals. Nevertheless, insufficient clinical data exist to advocate the general use of the palladium-copper and palladium-cobalt alloys at the present time. One should base the selection and use of these alloys in part on their ability to meet the requirements of the ADA Acceptance Program. A list of acceptable or provisionally acceptable alloys is available from the American Dental Association and is published annually in the Journal of the American Dental Association. Dentists have the legal and ethical responsibility for selection of alloys used for cast restorations. This responsibility should not be delegated to the dental laboratory technician. It is advisable to discuss the criteria for selection of an alloy with the technician and the

  14. Development and characterization of Powder Metallurgy (PM) 2XXX series Al alloy products and Metal Matrix Composite (MMC) 2XXX Al/SiC materials for high temperature aircraft structural applications

    NASA Technical Reports Server (NTRS)

    Chellman, D. J.; Gurganus, T. B.; Walker, J. A.

    1992-01-01

    The results of a series of material studies performed by the Lockheed Aeronautical Systems Company over the time period from 1980 to 1991 are discussed. The technical objective of these evaluations was to develop and characterize advanced aluminum alloy materials with temperature capabilities extending to 350 F. An overview is given of the first five alloy development efforts under this contract. Prior work conducted during the first five modifications of the alloy development program are listed. Recent developments based on the addition of high Zr levels to an optimum Al-Cu-Mg alloy composition by powder metallurgy processing are discussed. Both reinforced and SiC or B4C ceramic reinforced alloys were explored to achieve specific target goals for high temperature aluminum alloy applications.

  15. Corrosion resistance and cytocompatibility of biodegradable surgical magnesium alloy coated with hydrogenated amorphous silicon.

    PubMed

    Xin, Yunchang; Jiang, Jiang; Huo, Kaifu; Tang, Guoyi; Tian, Xiubo; Chu, Paul K

    2009-06-01

    The fast degradation rates in the physiological environment constitute the main limitation for the applications of surgical magnesium alloys as biodegradable hard-tissue implants. In this work, a stable and dense hydrogenated amorphous silicon coating (a-Si:H) with desirable bioactivity is deposited on AZ91 magnesium alloy using magnetron sputtering deposition. Raman spectroscopy and Fourier transform infrared spectroscopy reveal that the coating is mainly composed of hydrogenated amorphous silicon. The hardness of the coated alloy is enhanced significantly and the coating is quite hydrophilic as well. Potentiodynamic polarization results show that the corrosion resistance of the coated alloy is enhanced dramatically. In addition, the deterioration process of the coating in simulated body fluids is systematically investigated by open circuit potential evolution and electrochemical impedance spectroscopy. The cytocompatibility of the coated Mg is evaluated for the first time using hFOB1.19 cells and favorable biocompatibility is observed.

  16. Oxidation mechanisms for alloys in single-oxidant gases

    SciTech Connect

    Whittle, D.P.

    1981-03-01

    Scales formed on alloys invariably contain the alloy constituents in a ratio different from that in the alloy, owing to the differing thermodynamic tendencies of the alloy components to react with the oxidant and to differences in diffusion rates in scale and alloy phases. This complex interrelationship between transport rates and the thermodynamics of the alloy-oxidant system can be analyzed using multicomponent diffusion theory when transport-controlled growth of single or multi-layered scales occurs. In particular, the superimposition of the diffusion data on an isothermal section of the appropriate phase diagram indicates the likely morphologies of the reaction products, including the sequence of phases found in the scale, the occurrence of internal oxidation and the development of an irregular metal/scale interface. The scale morphologies on alloys are also time-dependent: there is an initial transient stage, a steady state period, and a final breakdown, the latter often related to mechanical influences such as scale adherence, spallation, thermal or mechanical stresses and void formation. Mechanical influences have a more devastating effect in alloy oxidation due to the changes in alloy surface composition during the steady state period.

  17. Development of radiation detectors based on hydrogenated amorphous silicon and its alloys

    SciTech Connect

    Hong, Wan-Shick

    1995-04-01

    Hydrogenated amorphous silicon and related materials have been applied to radiation detectors, utilizing their good radiation resistance and the feasibility of making deposits over a large area at low cost. Effects of deposition parameters on various material properties of a-Si:H have been studied to produce a material satisfying the requirements for specific detection application. Thick(-~50 μm), device quality a-Si:H p-i-n diodes for direct detection of minimum ionizing particles have been prepared with low internal stress by a combination of low temperature growth, He-dilution of silane, and post annealing. The structure of the new film contained voids and tiny crystalline inclusions and was different from the one observed in conventional a-Si:H. Deposition on patterned substrates was attempted as an alternative to controlling deposition parameters to minimize substrate bending and delamination of thick a-Si:H films. Growth on an inversed-pyramid pattern reduced the substrate bending by a factor of 3 ≈ 4 for the same thickness film. Thin (0.1 ≈ 0.2 μm) films of a-Si:H and a-SiC:H have been applied to microstrip gas chambers to control gain instabilities due to charges on the substrate. Light sensitivity of the a-Si:H sheet resistance was minimized and the surface resistivity was successfully` controlled in the range of 1012 ≈ 1017 Ω/(four gradient) by carbon alloying and boron doping. Performance of the detectors with boron-doped a-Si:C:H layers was comparable to that of electronic-conducting glass. Hydrogen dilution of silane has been explored to improve electrical transport properties of a-Si:H material for high speed photo-detectors and TFT applications.

  18. Evaluation of the corrosion resistance of Fe-Al-Cr alloys in simulated low NOx environments

    SciTech Connect

    Deacon, R.M.; DuPont, J.N.; Kiely, C.J.; Marder, A.R.; Tortorelli, P.F.

    2009-08-15

    Due to their excellent corrosion resistance, iron aluminum alloys are currently being considered for use as weld claddings in fossil fuel fired power plants. The susceptibility to hydrogen cracking of these alloys at higher aluminum concentrations has led researchers to examine the effect of chromium additions on the corrosion resistance of lower aluminum alloys. In this work, three iron aluminum alloys were exposed to simulated coal combustion environments at 500 and 700{sup o}C for short (100 h) and long (5000 h) isothermal durations. Scanning electron microscopy was used to analyze the corrosion products. All alloys exhibited excellent corrosion resistance during short term exposures. For longer test times, increasing the aluminum concentration improved alloy corrosion resistance. The addition of chromium to the binary iron aluminum alloy prevented the formation iron sulfide and resulted in slower corrosion kinetics. A general classification of the scales developed on these alloys is presented.

  19. High-temperature alloys: Single-crystal performance boost

    NASA Astrophysics Data System (ADS)

    Schütze, Michael

    2016-08-01

    Titanium aluminide alloys are lightweight and have attractive properties for high-temperature applications. A new growth method that enables single-crystal production now boosts their mechanical performance.

  20. Modern Sparingly Alloyed Titanium Alloys: Application and Prospects

    NASA Astrophysics Data System (ADS)

    Nochovnaya, N. A.; Panin, P. V.; Alekseev, E. B.; Bokov, K. A.

    2017-01-01

    Comparative analysis of the properties of domestic and foreign sparingly alloyed titanium alloys is preformed, and the main tendencies and prospects of their development are considered. Recent works of FGUP "VIAM" in the field of creation and approbation of various-purpose low-alloy titanium alloys are reviewed.

  1. Cesium iodide alloys

    DOEpatents

    Kim, H.E.; Moorhead, A.J.

    1992-12-15

    A transparent, strong CsI alloy is described having additions of monovalent iodides. Although the preferred iodide is AgI, RbI and CuI additions also contribute to an improved polycrystalline CsI alloy with outstanding multispectral infrared transmittance properties. 6 figs.

  2. Neutron Absorbing Alloys

    SciTech Connect

    Mizia, Ronald E.; Shaber, Eric L.; DuPont, John N.; Robino, Charles V.; Williams, David B.

    2004-05-04

    The present invention is drawn to new classes of advanced neutron absorbing structural materials for use in spent nuclear fuel applications requiring structural strength, weldability, and long term corrosion resistance. Particularly, an austenitic stainless steel alloy containing gadolinium and less than 5% of a ferrite content is disclosed. Additionally, a nickel-based alloy containing gadolinium and greater than 50% nickel is also disclosed.

  3. Copper-tantalum alloy

    DOEpatents

    Schmidt, Frederick A.; Verhoeven, John D.; Gibson, Edwin D.

    1986-07-15

    A tantalum-copper alloy can be made by preparing a consumable electrode consisting of an elongated copper billet containing at least two spaced apart tantalum rods extending longitudinally the length of the billet. The electrode is placed in a dc arc furnace and melted under conditions which co-melt the copper and tantalum to form the alloy.

  4. Ductile transplutonium metal alloys

    DOEpatents

    Conner, William V.

    1983-01-01

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as sources of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  5. Ductile transplutonium metal alloys

    DOEpatents

    Conner, W.V.

    1981-10-09

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as souces of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  6. Aluminum battery alloys

    DOEpatents

    Thompson, D.S.; Scott, D.H.

    1984-09-28

    Aluminum alloys suitable for use as anode structures in electrochemical cells are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  7. Aluminum battery alloys

    DOEpatents

    Thompson, David S.; Scott, Darwin H.

    1985-01-01

    Aluminum alloys suitable for use as anode structures in electrochemical cs are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  8. PLUTONIUM-CERIUM ALLOY

    DOEpatents

    Coffinberry, A.S.

    1959-01-01

    An alloy is presented for use as a reactor fuel. The binary alloy consists essentially of from about 5 to 90 atomic per cent cerium and the balance being plutonium. A complete phase diagram for the cerium--plutonium system is given.

  9. Ductile transplutonium metal alloys

    SciTech Connect

    Conner, W.V.

    1983-04-19

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as sources of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  10. Property Criteria for Automotive Al-Mg-Si Sheet Alloys.

    PubMed

    Prillhofer, Ramona; Rank, Gunther; Berneder, Josef; Antrekowitsch, Helmut; Uggowitzer, Peter J; Pogatscher, Stefan

    2014-07-04

    In this study, property criteria for automotive Al-Mg-Si sheet alloys are outlined and investigated in the context of commercial alloys AA6016, AA6005A, AA6063 and AA6013. The parameters crucial to predicting forming behavior were determined by tensile tests, bending tests, cross-die tests, hole-expansion tests and forming limit curve analysis in the pre-aged temper after various storage periods following sheet production. Roping tests were performed to evaluate surface quality, for the deployment of these alloys as an outer panel material. Strength in service was also tested after a simulated paint bake cycle of 20 min at 185 °C, and the corrosion behavior was analyzed. The study showed that forming behavior is strongly dependent on the type of alloy and that it is influenced by the storage period after sheet production. Alloy AA6016 achieves the highest surface quality, and pre-ageing of alloy AA6013 facilitates superior strength in service. Corrosion behavior is good in AA6005A, AA6063 and AA6016, and only AA6013 shows a strong susceptibility to intergranular corrosion. The results are discussed below with respect to the chemical composition, microstructure and texture of the Al-Mg-Si alloys studied, and decision-making criteria for appropriate automotive sheet alloys for specific applications are presented.

  11. Property Criteria for Automotive Al-Mg-Si Sheet Alloys

    PubMed Central

    Prillhofer, Ramona; Rank, Gunther; Berneder, Josef; Antrekowitsch, Helmut; Uggowitzer, Peter J.; Pogatscher, Stefan

    2014-01-01

    In this study, property criteria for automotive Al-Mg-Si sheet alloys are outlined and investigated in the context of commercial alloys AA6016, AA6005A, AA6063 and AA6013. The parameters crucial to predicting forming behavior were determined by tensile tests, bending tests, cross-die tests, hole-expansion tests and forming limit curve analysis in the pre-aged temper after various storage periods following sheet production. Roping tests were performed to evaluate surface quality, for the deployment of these alloys as an outer panel material. Strength in service was also tested after a simulated paint bake cycle of 20 min at 185 °C, and the corrosion behavior was analyzed. The study showed that forming behavior is strongly dependent on the type of alloy and that it is influenced by the storage period after sheet production. Alloy AA6016 achieves the highest surface quality, and pre-ageing of alloy AA6013 facilitates superior strength in service. Corrosion behavior is good in AA6005A, AA6063 and AA6016, and only AA6013 shows a strong susceptibility to intergranular corrosion. The results are discussed below with respect to the chemical composition, microstructure and texture of the Al-Mg-Si alloys studied, and decision-making criteria for appropriate automotive sheet alloys for specific applications are presented. PMID:28788119

  12. Iron/Phosphorus Alloys for Continuous Casting

    NASA Technical Reports Server (NTRS)

    Dufresne, E. R.

    1986-01-01

    Continuous casting becomes practicable because of reduced eutectic temperature. Experimental ferrous alloy has melting point about 350 degrees C lower than conventional steels, making possible to cast structural members and eliminating need for hot rolling. Product has normal metal structure and good physical properties. Process used to make rails, beams, slabs, channels, and pipes.

  13. Failure mechanism characterization of platinum alloy

    NASA Technical Reports Server (NTRS)

    Rosen, J. M.; Mcfarlen, W. T.

    1986-01-01

    This article describes procedures and results of testing performed on a platinum/10-percent rhodium, thin-wall tubular product. The purpose of the testing was to develop exemplar SEM fractographs to be used to characterize failures under various environmental conditions. Conditions evaluated for the platinum alloys included high temperature, hydrogen environment, braze metal contamination, and cyclic loading.

  14. Iron/Phosphorus Alloys for Continuous Casting

    NASA Technical Reports Server (NTRS)

    Dufresne, E. R.

    1986-01-01

    Continuous casting becomes practicable because of reduced eutectic temperature. Experimental ferrous alloy has melting point about 350 degrees C lower than conventional steels, making possible to cast structural members and eliminating need for hot rolling. Product has normal metal structure and good physical properties. Process used to make rails, beams, slabs, channels, and pipes.

  15. Ultrahigh temperature intermetallic alloys

    SciTech Connect

    Brady, M.P.; Zhu, J.H.; Liu, C.T.; Tortorelli, P.F.; Wright, J.L.; Carmichael, C.A.; Walker, L.R.

    1997-12-01

    A new family of Cr-Cr{sub 2}X based alloys with fabricability, mechanical properties, and oxidation resistance superior to previously developed Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr based alloys has been identified. The new alloys can be arc-melted/cast without cracking, and exhibit excellent room temperature and high-temperature tensile strengths. Preliminary evaluation of oxidation behavior at 1100 C in air indicates that the new Cr-Cr{sub 2}X based alloys form an adherent chromia-based scale. Under similar conditions, Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr based alloys suffer from extensive scale spallation.

  16. Alloys in energy development

    SciTech Connect

    Frost, B.R.T.

    1984-02-01

    The development of new and advanced energy systems often requires the tailoring of new alloys or alloy combinations to meet the novel and often stringent requirements of those systems. Longer life at higher temperatures and stresses in aggressive environments is the most common goal. Alloy theory helps in achieving this goal by suggesting uses of multiphase systems and intermediate phases, where solid solutions were traditionally used. However, the use of materials under non-equilibrium conditions is now quite common - as with rapidly solidified metals - and the application of alloy theory must be modified accordingly. Under certain conditions, as in a reactor core, the rate of approach to equilibrium will be modified; sometimes a quasi-equilibrium is established. Thus an alloy may exhibit enhanced general diffusion at the same time as precipitate particles are being dispersed and solute atoms are being carried to vacancy sinks. We are approaching an understanding of these processes and can begin to model these complex systems.

  17. Alloying effect on K X-ray intensity ratios, K X-ray production cross-sections and radiative Auger ratios in superalloys constitute from Al, Ni and Mo elements

    NASA Astrophysics Data System (ADS)

    Aylikci, N. Kup; Tiraşoğlu, E.; Karahan, İ. H.; Aylikci, V.; Eskil, M.; Cengiz, E.

    2010-11-01

    In this study, σ production cross-sections, Kβ/ Kα, KLM/ Kα and KMM/ Kβ RAE intensity ratios of Ni and σ,σ production cross-sections, Kβ1,3/ Kα, Kβ2,4/ Kα, Kβ2,4/ Kβ1,3, KLM/ Kα and KMM/ Kβ RAE intensity ratios of Mo have been measured in pure metals and in superalloy specimens. The samples were excited by 59.5 keV γ-rays from a 241Am annular radioactive source. K X-rays emitted by samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV. The effect of alloying on the fluorescence parameters of Ni and Mo, phase structure, and corrosion behavior were investigated. The X-ray fluorescence parameters of Ni and Mo in superalloys indicate significant differences with respect to the pure metals. These differences are attributed to the reorganization of valence shell electrons and/or charge transfer phenomena in superalloys.

  18. Silicon germanium semiconductive alloy and method of fabricating same

    NASA Technical Reports Server (NTRS)

    Park, Yeonjoon (Inventor); Choi, Sang H. (Inventor); King, Glen C. (Inventor)

    2008-01-01

    A silicon germanium (SiGe) semiconductive alloy is grown on a substrate of single crystalline Al.sub.2O.sub.3. A {111} crystal plane of a cubic diamond structure SiGe is grown on the substrate's {0001} C-plane such that a <110> orientation of the cubic diamond structure SiGe is aligned with a <1,0,-1,0> orientation of the {0001} C-plane. A lattice match between the substrate and the SiGe is achieved by using a SiGe composition that is 0.7223 atomic percent silicon and 0.2777 atomic percent germanium.

  19. Effect of Deposition Conditions on Intrinsic Stress in a-Si: H Films

    NASA Astrophysics Data System (ADS)

    Ozawa, Kiyoshi; Takagi, Nobuyoshi; Asama, Kunihiko

    1983-05-01

    Intrinsic stress in the a-Si: H film, which reflects the internal microstructure of the film under deposition and thus gives the information about the construction of amorphous network, has been evaluated by the Baser interferometric method. The intrinsic stress induced in the a-Si: H film is compressive and increases with the deposition temperature. As the intrinsic compressive stress is increased, decreases are observed in the deposition rate, the total hydrogen concentration, and the ratio of hydrogen concentration with the configuration SiH2, SiH3, and (SiH2)n to that with SiH. These results on the temperature dependence of a-Si: H film growth indicate that the contribution of excited species in the plasma to the growth of the a-Si: H is restricted by the intrinsic compressive stress induced in the a-Si: H through differences in molecular dimensions of the excited species.

  20. Amorphous Si thin film based photocathodes with high photovoltage for efficient hydrogen production.

    PubMed

    Lin, Yongjing; Battaglia, Corsin; Boccard, Mathieu; Hettick, Mark; Yu, Zhibin; Ballif, Christophe; Ager, Joel W; Javey, Ali

    2013-01-01

    An amorphous Si thin film with TiO2 encapsulation layer is demonstrated as a highly promising and stable photocathode for solar hydrogen production. With platinum as prototypical cocatalyst, a photocurrent onset potential of 0.93 V vs RHE and saturation photocurrent of 11.6 mA/cm(2) are measured. Importantly, the a-Si photocathodes exhibit impressive photocurrent of ~6.1 mA/cm(2) at a large positive bias of 0.8 V vs RHE, which is the highest for all reported photocathodes at such positive potential. Ni-Mo alloy is demonstrated as an alternative low-cost catalyst with onset potential and saturation current similar to those obtained with platinum. This low-cost photocathode with high photovoltage and current is a highly promising photocathode for solar hydrogen production.

  1. Calculations and First Results Obtained with a SiC Prototype of the SPES Direct Target

    SciTech Connect

    Barbui, Marina; Andrighetto, Alberto; Antonucci, C.; Biasetto, Lisa; Carturan, S.; Cervellera, F.; Cevolani, S.; Cinausero, Marco; Colombo, P.; Dainelli, A.; Di Bernardo, P.; Giacchini, Mauro; Gramegna, Fabiana; Lollo, M.; Maggioni, G.; Manzolaro, Mattia; Meneghetti, G.; Petrovich, C.; Piga, L.; Prete, Gianfranco; Re, Maurizio; Rizzi, Valentina; Stracener, Daniel W; Tonezzer, Michele; Zafiropoulos, D.; Zanonato, P.

    2008-01-01

    In the framework of the SPES project at LNL [A. Bracco, A. Pisent (Ed.), REP 181/02, LNL-INFN, 2002], the realization of a direct ISOL Target for a mid-term radioactive ion beam facility is in progress. Using a primary proton beam of energy 40 MeV and intensity 0.2 mA, a high number of fission products will be obtained in the SPES multi-foil uranium carbide target, keeping a low power density deposition in the refractory matrix [A. Andrighetto, S. Cevolani, C. Petrovich, Eur. Phys J. A 25 (2005) 41]. The exotic species produced by Uranium fission in the target are collected in the ion source after the diffusion and the effusion processes. When short lived isotopes are produced it is very important to optimize the release properties of the target. To this purpose the RIBO code (radioactive ion beam optimiser) [M. Santana Leitner, A Monte Carlo Code to Optimize the Production of Radioactive Ion Beams by the ISOL Technique, PhD. Thesis, UPC-ETSEIB/CERN] has been used in order to estimate the target release efficiency for some neutron-rich nuclei. A SiC prototype of the target was recently produced at LNL and tested at ORNL using a 42 MeV proton beam. The yield of some aluminum isotopes was measured as a function of the target temperature. Some preliminary results of the data analysis will be presented.

  2. Tunneling Spectroscopy of Amorphous Magnetic Rare Earth-Si Alloys near the Metal-Insulator Transition

    NASA Astrophysics Data System (ADS)

    Xiong, P.; Zink, B. L.; Tran, M. Q.; Gebala, A. E.; Wilcox, E. M.; Hellman, F.; Dynes, R. C.

    1997-03-01

    Amorphous dilute magnetic semiconductors exhibit striking differences in the electrical and magneto-transport behavior from their crystalline or nonmagnetic analogs.(F. Hellman et al., Phys. Rev. Lett. 77, 4652 (1996).) Magnetic impurities cause a large suppression of conductivity below 50 K in a-Si_xGd_1-x and a-Si_xTb_1-x relative to the nonmagnetic a-Si_xY_1-x (x ~ 0.85-0.9). Application of a magnetic field increases the conductivity by orders of magnitude. We have fabricated good quality tunnel junctions on a-Si:Gd and the nonmagnetic a-Si:Y to probe the electronic density of states in these two systems. We present the results of the tunneling spectroscopy and its magnetic field dependence for a series of the two alloys at different compositions. We will discuss the correlation between the tunneling spectra and the transport properties and its implications on the possible origin of the magnetic field tuned insulator-metal transition in a-Si:Gd. Research Supported by ONR Grant No. N000149151320 and NSF Grant No. DMR-9208599.

  3. Electron cyclotron resonance deposition of amorphous silicon alloy films and devices

    SciTech Connect

    Shing, Y.H. )

    1992-10-01

    This report describes work to develop a state-of-the-art electron cyclotron resonance (ECR) plasma-enhanced chemical vapor deposition (PECVD) system. The objective was to understand the deposition processes of amorphous silicon (a-Si:H) and related alloys, with a best-effort improvement of optoelectronic material properties and best-effort stabilization of solar cell performance. ECR growth parameters were systematically and extensively investigated; materials characterization included constant photocurrent measurement (CPM), junction capacitance, drive-level capacitance profiling (DLCP), optical transmission, light and dark photoconductivity, and small-angle X-ray scattering (SAXS). Conventional ECR-deposited a-Si:H was compared to a new form, a-Si:(Xe, H), in which xenon gas was added to the ECR plasma. a-Si:(Xe,H) possessed low, stable dark conductivities and high photosensitivites. Light-soaking revealed photodegradation rates about 35% lower than those of comparable radio frequency (rf)-deposited material. ECR-deposited p-type a SiC:H and intrinsic a-Si:H films underwent evaluation as components of p-i-n solar cells with standard rf films for the remaining layers.

  4. Process for alloying uranium and niobium

    DOEpatents

    Holcombe, Cressie E.; Northcutt, Jr., Walter G.; Masters, David R.; Chapman, Lloyd R.

    1991-01-01

    Alloys such as U-6Nb are prepared by forming a stacked sandwich array of uraniun sheets and niobium powder disposed in layers between the sheets, heating the array in a vacuum induction melting furnace to a temperature such as to melt the uranium, holding the resulting mixture at a temperature above the melting point of uranium until the niobium dissolves in the uranium, and casting the uranium-niobium solution. Compositional uniformity in the alloy product is enabled by use of the sandwich structure of uranium sheets and niobium powder.

  5. Aluminum-lithium alloys with hafnium

    SciTech Connect

    Rioja, R.J.; Bretz, P.E.; Jacoby, J.

    1989-09-26

    This patent describes an aluminum base alloy suitable for forming into a wrought product having improved combinations of strength and fracture toughness. The alloy consisting essentially of 0.2 to 5.0 wt % Li, 0.05 to 6.0 wt % Mg, 0.2 to 5.0 wt % Cu, 0 to 2.0 wt % Mn, 0 to 1.0 wt, % Zr, 0.05 to 12.0 wt. % Zn, 0.05 to 1.0 wt. % Hf, 0.5 wt.% Fe, 0.5 wt. % max. Si, the balance aluminum and incidental impurities.

  6. Corrosion protection of aerospace grade magnesium alloy Elektron 43(TM) for use in aircraft cabin interiors

    NASA Astrophysics Data System (ADS)

    Baillio, Sarah S.

    Magnesium alloys exhibit desirable properties for use in transportation technology. In particular, the low density and high specific strength of these alloys is of interest to the aerospace community. However, the concerns of flammability and susceptibility to corrosion have limited the use of magnesium alloys within the aircraft cabin. This work studies a magnesium alloy containing rare earth elements designed to increase resistance to ignition while lowering rate of corrosion. The microstructure of the alloy was documented using scanning electron microscopy. Specimens underwent salt spray testing and the corrosion products were examined using energy dispersive spectroscopy.

  7. Subtask 12D2: Baseline impact properties of vanadium alloys

    SciTech Connect

    Chung, H.M.; Loomis, B.A.; Smith, D.L.

    1995-03-01

    The objective of this work is to determine the baseline impact properties of vanadium-base alloys as a function of compositional variables. Up-to-date results on impact properties of unirradiated V, V-Ti, V-Cr-Ti and V-Ti-Si alloys are presented and reviewed in this paper, with an emphasis on the most promising class of alloys, i.e., V-(4-5)Cr-(3-5)Ti containing 400-1000 wppm Si. Database on impact energy and ductile-brittle transition temperature (DBTT) has been established from Charpy impact tests on small laboratory as well as production-scale heats. DBTT is influenced most significantly by Cr contents and, to a lesser extent, by Ti contents of the alloys. When combined contents of Cr and Ti were {le}10 wt.%, V-Cr-Ti alloys exhibit excellent impact properties, i.e., DBTT<-200{degrees}C and upper shelf energies of {approx}120-140 J/cm{sup 2}. Impact properties of the production-scale heat of the U.S. reference alloy V-4Cr- 4Ti were as good as those of the laboratory-scale heats. Optimal impact properties of the reference alloy were obtained after annealing the as-rolled products at 1000{degrees}C-1050{degrees}C for 1-2 h in high-quality vacuum. 17 refs., 6 figs., 2 tabs.

  8. THORIUM-SILICON-BERYLLIUM ALLOYS

    DOEpatents

    Foote, F.G.

    1959-02-10

    Th, Si, anol Bt alloys where Be and Si are each present in anmounts between 0.1 and 3.5% by weight and the total weight per cent of the minor alloying elements is between 1.5 and 4.5% are discussed. These ternary alloys show increased hardness and greater resistant to aqueous corrosion than is found in pure Th, Th-Si alloys, or Th-Be alloys.

  9. Milling and Drilling Evaluation of Stainless Steel Powder Metallurgy Alloys

    SciTech Connect

    Lazarus, L.J.

    2001-12-10

    Near-net-shape components can be made with powder metallurgy (PM) processes. Only secondary operations such as milling and drilling are required to complete these components. In the past and currently production components are made from powder metallurgy (PM) stainless steel alloys. process engineers are unfamiliar with the difference in machining properties of wrought versus PM alloys and have had to make parts to develop the machining parameters. Design engineers are not generally aware that some PM alloy variations can be furnished with machining additives that greatly increase tool life. Specimens from a MANTEC PM alloy property study were made available. This study was undertaken to determine the machining properties of a number of stainless steel wrought and PM alloys under the same conditions so that comparisons of their machining properties could be made and relative tool life determined.

  10. Refractory alloy technology for space nuclear power applications

    SciTech Connect

    Cooper, R.H. Jr.; Hoffman, E.E.

    1984-01-01

    Purpose of this symposium is twofold: (1) to review and document the status of refractory alloy technology for structural and fuel-cladding applications in space nuclear power systems, and (2) to identify and document the refractory alloy research and development needs for the SP-100 Program in both the short and the long term. In this symposium, an effort was made to recapture the space reactor refractory alloy technology that was cut off in midstream around 1973 when the national space nuclear reactor program began in the early 1960s, was terminated. The six technical areas covered in the program are compatibility, processing and production, welding and component fabrication, mechanical and physical properties, effects of irradiation, and machinability. The refractory alloys considered are niobium, molybdenum, tantalum, and tungsten. Thirteen of the 14 pages have been abstracted separately. The remaining paper summarizes key needs for further R and D on refractory alloys. (DLC)

  11. Thermo-Mechanical Processing Parameters for the INCONEL ALLOY 740

    SciTech Connect

    Ludtka, G.M.; Smith, G.

    2007-11-19

    In 2000, a Cooperative Research and Development Agreement (CRADA) was undertaken between the Oak Ridge National Laboratory (ORNL) and the Special Metals Corporation (SMC) to determine the mechanical property response of the IN740 alloy to help establish thermo-mechanical processing parameters for the use of this alloy in supercritical and ultra-critical boiler tubes with the potential for other end uses. SMC had developed an alloy, commercially known as INCONEL alloy 740, which exhibited various beneficial physical, mechanical, and chemical properties. As part of SMC's on-going efforts to optimize this alloy for targeted boiler applications there was a need to develop an understanding of the thermo-mechanical response of the material, characterize the resulting microstructure from this processing, and possibly, utilize models to develop the appropriate processing scheme for this product.

  12. Security assessment of magnesium alloys used as biodegradable implant material.

    PubMed

    Sun, X; Cao, Z Y; Liu, J G; Feng, C

    2015-01-01

    The security risk of magnesium alloys used as biodegradable implant material was evaluated in this study. Dose-response assessment was conducted by using toxicological data from authoritative public health agencies (World Health Organization) and assuming 1~3 years of uniform corrosion. Through modification calculation, the tolerable corrosion rate of biodegradable magnesium alloys in vivo was proposed, which theoretically ensured the bio-safety of the degradation products. The tolerable limits corresponding to various component elements in magnesium alloys were considered separately, although there are deficits in the toxicological data of some component elements. The influence of corrosion on the strength of magnesium alloys was evaluated, which would contribute to the rationally utilization of magnesium alloys as degradable implant materials. This study illustrates that not only toxicological calculations but also mechanical performance should be taken into consideration when developing novel degradable metallic implant.

  13. The Mg impurity in nitride alloys

    SciTech Connect

    Zvanut, M. E.; Willoughby, W. R.; Sunay, U. R.; Koleske, D. D.; Allerman, A. A.; Wang, Ke; Araki, Tsutomu; Nanishi, Yasushi

    2014-02-21

    Although several magnetic resonance studies address the Mg acceptor in GaN, there are few reports on Mg doping in the alloys, where hole production depends strongly on the Al or In content. Our electron paramagnetic resonance (EPR) measurements of the p-type alloys suggest that the Mg impurity retains the axial symmetry, characteristic of a p-type dopant in both alloys; however, In and Al produce additional, different characteristics of the acceptor. In InGaN, the behavior is consistent with a lowering of the acceptor level and increasing hole density as In concentration increases. For AlGaN, the amount of neutral Mg decreases with increasing Al content, which is attributed to different kinetics of hydrogen diffusion thought to occur in samples with higher Al mole fraction.

  14. Melt Conditioned Casting of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Scamans, Geoff; Li, Hu-Tian; Fan, Zhongyun

    High shear melt conditioning of aluminum alloy melts disperses oxide films and provides potent nuclei to promote non-dendritic solidification leading to refined as cast microstructures for shape castings, semis or continuously cast product forms. A new generation of high shear melt conditioning equipment has been developed based on a dispersive mixer that can condition either a batch melt or can provide a continuous melt feed. Most significantly the melt conditioner can be used directly in the sump of a DC caster where it has a dramatic effect on the cast microstructure. The present goals are to expand the castable alloy range and to increase the tolerance of alloys used in transport applications to impurities to increase the use of recycled metal. The paper will review the current status of the melt conditioning technology across the range of casting options and will highlight development opportunities.

  15. Magnesium silicide intermetallic alloys

    NASA Astrophysics Data System (ADS)

    Li, Gh.; Gill, H. S.; Varin, R. A.

    1993-11-01

    Methods of induction melting an ultra-low-density magnesium silicide (Mg2Si) intermetallic and its alloys and the resulting microstructure and microhardness were studied. The highest quality ingots of Mg2Si alloys were obtained by triple melting in a graphite crucible coated with boron nitride to eliminate reactivity, under overpressure of high-purity argon (1.3 X 105 Pa), at a temperature close to but not exceeding 1105 °C ± 5 °C to avoid excessive evaporation of Mg. After establishing the proper induction-melting conditions, the Mg-Si binary alloys and several Mg2Si alloys macroalloyed with 1 at. pct of Al, Ni, Co, Cu, Ag, Zn, Mn, Cr, and Fe were induction melted and, after solidification, investigated by optical microscopy and quantitative X-ray energy dispersive spectroscopy (EDS). Both the Mg-rich and Si-rich eutectic in the binary alloys exhibited a small but systematic increase in the Si content as the overall composition of the binary alloy moved closer toward the Mg2Si line compound. The Vickers microhardness (VHN) of the as-solidified Mg-rich and Si-rich eutectics in the Mg-Si binary alloys decreased with increasing Mg (decreasing Si) content in the eutectic. This behavior persisted even after annealing for 75 hours at 0.89 pct of the respective eutectic temperature. The Mg-rich eutectic in the Mg2Si + Al, Ni, Co, Cu, Ag, and Zn alloys contained sections exhibiting a different optical contrast and chemical composition than the rest of the eutectic. Some particles dispersed in the Mg2Si matrix were found in the Mg2Si + Cr, Mn, and Fe alloys. The EDS results are presented and discussed and compared with the VHN data.

  16. Impact Behavior of A356 Foundry Alloys in the Presence of Trace Elements Ni and V

    NASA Astrophysics Data System (ADS)

    Casari, Daniele; Ludwig, Thomas H.; Merlin, Mattia; Arnberg, Lars; Garagnani, Gian Luca

    2015-02-01

    In the present work, the impact behavior of unmodified A356 alloys with the addition of Ni or V in as-cast and T6 heat-treated conditions was assessed. Charpy V-notched specimens obtained from sand and permanent mold casting showed low total absorbed energy average values ( W t < 2 J). SEM analysis of fracture profiles and surfaces indicated a Si-driven crack propagation with a predominant transgranular fracture mode. Occasionally, intergranular contributions to fracture were detected in the permanent mold cast alloys due to the locally finer microstructure. Concurrent mechanisms related to the chemical composition, solidification conditions and heat treatment were found to control the impact properties of the alloys. While the trace element Ni exerted only minor effects on the impact toughness of the A356 alloy, V had a strong influence: (i) V-containing sand cast alloys absorbed slightly higher impact energies compared to the corresponding A356 base alloys; (ii) in the permanent mold cast alloys, V in solid solution led to a considerable loss of ductility, which in turn decreased the total absorbed energy.

  17. The role of dispersoids in maintaining the corrosion resistance of mechanically alloyed oxide dispersion strengthened alloys

    SciTech Connect

    Cama, H.; Hughes, T.A.

    1995-05-15

    Amongst the various commercial mechanically alloyed (MA) oxide dispersion strengthened (ODS) alloys available, ferritic alloys are most suitable for use at temperatures exceeding 1,100 C, since {gamma}{prime} particle dissolution results in the loss of strength of nickel based MA ODS alloys. In commercial MA ODS alloys, yttria particles are commonly added in the starting powers, and it is well known that they are not retained in the final product because they react with aluminum and oxygen present in the system during thermomechanical processing and form mixed (Y,Al) oxide particles. In this paper the role of (Y,Al) oxide particles in maintaining the overall aluminum concentration in the matrix necessary to repair the outer oxide scale is discussed. It is well known that during exposure in air, aluminum is lost from the bulk of MA ODS alloys to the growth of a surface alumina film. The extent of aluminum lost is dependent on the section thickness and can significantly affect the volume fraction of the aluminum rich dispersoids. Coarsening of the dispersoids at temperatures up to 1,200 C in the thick MA 956 bar occurs without significant aluminum loss, while their volume fraction increases continuously. However, coarsening of the dispersoids in the thinner ODM 751 tube at 1,200 and 1,300 C is accompanied by dissolution of the dispersoid particles in order to maintain the aluminum concentration in the matrix.

  18. Analysis of niobium alloys.

    PubMed

    Ferraro, T A

    1968-09-01

    An ion-exchange method was applied to the analysis of synthetic mixtures representing various niobium-base alloys. The alloying elements which were separated and determined include vanadium, zirconium, hafnium, titanium, molybdenum, tungsten and tantalum. Mixtures containing zirconium or hafnium, tungsten, tantalum and niobium were separated by means of a single short column. Coupled columns were employed for the resolution of mixtures containing vanadium, zirconium or titanium, molybdenum, tungsten and niobium. The separation procedures and the methods employed for the determination of the alloying elements in their separate fractions are described.

  19. TUNGSTEN BASE ALLOYS

    DOEpatents

    Schell, D.H.; Sheinberg, H.

    1959-12-15

    A high-density quaternary tungsten-base alloy having high mechanical strength and good machinability composed of about 2 wt.% Ni, 3 wt.% Cu, 5 wt.% Pb, and 90wt.% W is described. This alloy can be formed by the powder metallurgy technique of hot pressing in a graphite die without causing a reaction between charge and the die and without formation of a carbide case on the final compact, thereby enabling re-use of the graphite die. The alloy is formable at hot- pressing temperatures of from about 1200 to about 1350 deg C. In addition, there is little component shrinkage, thereby eliminating the necessity of subsequent extensive surface machining.

  20. 77 FR 73015 - Circular Welded Non-Alloy Steel Pipe From the Republic of Korea: Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-07

    ... International Trade Administration Circular Welded Non-Alloy Steel Pipe From the Republic of Korea: Preliminary... conducting an administrative review of the antidumping duty order on circular welded non-alloy steel pipe... merchandise subject to the order is circular welded non-alloy steel pipe and tube. The product is...

  1. 77 FR 66954 - Carbon and Certain Alloy Steel Wire Rod From Mexico: Preliminary Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-08

    ... International Trade Administration Carbon and Certain Alloy Steel Wire Rod From Mexico: Preliminary Results of... on carbon and certain alloy steel wire rod (wire rod) from Mexico. The period of review is October 1... certain alloy steel wire rod. The product is currently classified under the Harmonized Tariff Schedule...

  2. Electrical Resistivity of Ten Selected Binary Alloy Systems.

    DTIC Science & Technology

    1981-04-01

    alloys --* Aluminum Alloys --*Copper alloys --*Gold alloys --*Nickel Alloys --*Silver alloys --*Iron alloys --*Palladium alloys ... aluminum -magnesium, and copper-zinc) are given for 27 compositions: 0 (pure element).* For aluminum -copper, aluninu.-eagnes tur, end copper-zinc alloy ...available data and infor- mation. The ten binary alloy systems selected are the systems of aluminum - copper, aluminum -magnesium, copper-gold,

  3. Atomistic study of the structural and electronic properties of a-Si:H/c-Si interfaces.

    PubMed

    Santos, Iván; Cazzaniga, Marco; Onida, Giovanni; Colombo, Luciano

    2014-03-05

    We investigate the structural and electronic properties of the interface between hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si) by combining tight-binding molecular dynamics and DFT ab initio electronic structure calculations. We focus on the c-Si(100)(1×1)/a-Si:H, c-Si(100)(2×1)/a-Si:H and c-Si(111)/a-Si:H interfaces, due to their technological relevance. The analysis of atomic rearrangements induced at the interface by the interaction between H and Si allowed us to identify the relevant steps that lead to the transformation from c-Si(100)(1×1)/a-Si:H to c-Si(100)(2×1)/a-Si:H. The interface electronic structure is found to be characterized by spatially localized mid-gap states. Through them we have identified the relevant atomic structures responsible for the interface defect states, namely: dangling-bonds, H bridges, and strained bonds. Our analysis contributes to a better understanding of the role of such defects in c-Si/a-Si:H interfaces.

  4. An NMR investigation of H cluster configurations in a-Si:H

    SciTech Connect

    Stephen, J.T.; Rutland, J.M.; Han, D.; Wu, Y.

    1997-07-01

    In this work the characteristics of hydrogen clusters in hot filament assisted CVD and conventional glow discharge a-Si:H films are discussed. Computer simulations of the observed free-induction decays of the {sup 1}H NMR signals indicate that the distribution of the nearest-neighbor distances between H atoms in the H clusters is quite narrow in hot filament assisted CVD a-Si:H whereas the distribution is larger in glow discharge a-Si:H. This is clear evidence of improved structural order in hot filament assisted CVD a-Si:H. The relaxed hydrogenated divacancy and multi-vacancy models reproduce the main features of the observed free-induction decay in hot-wire a-Si:H very well. Computer simulations of the multiple-quantum NMR spectra indicate that a relaxed hydrogenated divacancy configuration leads to good agreement with experimental observations in device quality glow discharge a-Si:H. Results of simulations based on other H cluster configurations are also discussed. These results provide restrictions on the possible models for H clusters in a-Si:H.

  5. On the cytocompatibility of biodegradable Fe-based alloys.

    PubMed

    Schinhammer, Michael; Gerber, Isabel; Hänzi, Anja C; Uggowitzer, Peter J

    2013-03-01

    Biodegradable iron-based alloys are potential candidates for application as temporary implant material. This study summarizes the design strategy applied in the development of biodegradable Fe-Mn-C-Pd alloys and describes the key factors which make them suitable for medical applications. The study's in vitro cytotoxicity tests using human umbilical vein endothelial cells revealed acceptable cytocompatibility based on the alloys' eluates. An analysis of the eluates revealed that Fe is predominantly bound in insoluble degradation products, whereas a considerable amount of Mn is in solution. The investigation's results are discussed using dose-response curves for the main alloying elements Fe and Mn. They show that it is mainly Mn which limits the cytocompatibility of the alloys. The study also supplies a summary of the alloying elements' influence on metabolic processes. The results and discussion presented are considered important and instructive for future alloy development. The Fe-based alloys developed show an advantageous combination of microstructural, mechanical and biological properties, which makes them interesting as degradable implant material.

  6. Parameter variation of the one-diode model of a-Si and a- Si/μc-Si solar cells for modeling light-induced degradation

    NASA Astrophysics Data System (ADS)

    Weicht, J. A.; Hamelmann, F. U.; Behrens, G.

    2014-11-01

    For analyzing the long-term behavior of thin film a-Si/μc-Si photovoltaic modules, it is important to observe the light-induced degradation (LID) in dependence of the temperature for the parameters of the one-diode model for solar cells. According to the IEC 61646 standard, the impact of LID on module parameters of these thin film cells is determined at a constant temperature of 50°C with an irradiation of 1000 W/m2 at open circuit conditions. Previous papers examined the LID of thin film a-Si cells with different temperatures and some others are about a-Si/μc-Si. In these previous papers not all parameters of the one-diode model are examined. We observed the serial resistance (Rs), parallel resistance (Rp), short circuit current (Isc), open circuit voltage (Uoc), the maximum power point (MPP: Umpp, Impp and Pmpp) and the diode factor (n). Since the main reason for the LID of silicon-based thin films is the Staebler Wronski effect in the a-Si part of the cell, the temperature dependence of the healing of defects for all parameters of the one-diode model is also taken into account. We are also measuring modules with different kind of transparent conductive oxides: In a-Si thin film solar cells fluorine-doped tin oxide (FTO) is used and for thin film solar cells of a-Si/μc-Si boron- doped zinc oxide is used. In our work we describe an approach for transferring the parameters of a one-diode model for tandem thin film solar cells into the one-diode model for each part of the solar cell. The measurement of degradation and regeneration at higher temperatures is the necessary base for optimization of the different silicon-based thin films in warm hot climate.

  7. Influence of alloy microstructure on the microshear bond strength of basic alloys to a resin luting cement.

    PubMed

    Bauer, José; Costa, José Ferreira; Carvalho, Ceci Nunes; Souza, Douglas Nesadal de; Loguercio, Alessandro Dourado; Grande, Rosa Helena Miranda

    2012-01-01

    The aim of this study was to evaluate the influence of microstructure and composition of basic alloys on their microshear bond strength (µSBS) to resin luting cement. The alloys used were: Supreme Cast-V (SC), Tilite Star (TS), Wiron 99 (W9), VeraBond II (VBII), VeraBond (VB), Remanium (RM) and IPS d.SIGN 30 (IPS). Five wax patterns (13 mm in diameter and 4mm height) were invested, and cast in a centrifugal casting machine for each basic alloy. The specimens were embedded in resin, polished with a SiC paper and sandblasted. After cleaning the metal surfaces, six tygon tubes (0.5 mm height and 0.75 mm in diameter) were placed on each alloy surface, the resin cement (Panavia F) was inserted, and the excess was removed before light-curing. After storage (24 h/37°C), the specimens were subjected to µSBS testing (0.5 mm/min). The data were subjected to a one-way repeated measures analysis of variance and Turkey's test (α=0.05). After polishing, their microstructures were revealed with specific conditioners. The highest µSBS (mean/standard deviation in MPa) were observed in the alloys with dendritic structure, eutectic formation or precipitation: VB (30.6/1.7), TS (29.8/0.9), SC (30.6/1.7), with the exception of IPS (31.1/0.9) which showed high µSBS but no eutectic formation. The W9 (28.1/1.5), VBII (25.9/2.0) and RM (25.9/0.9) showed the lowest µSBS and no eutectic formation. It seems that alloys with eutectic formation provide the highest µSBS values when bonded to a light-cured resin luting cement.

  8. Electroplating on titanium alloy

    NASA Technical Reports Server (NTRS)

    Lowery, J. R.

    1971-01-01

    Activation process forms adherent electrodeposits of copper, nickel, and chromium on titanium alloy. Good adhesion of electroplated deposits is obtained by using acetic-hydrofluoric acid anodic activation process.

  9. Brazing dissimilar aluminum alloys

    NASA Technical Reports Server (NTRS)

    Dalalian, H.

    1979-01-01

    Dip-brazing process joins aluminum castings to aluminum sheet made from different aluminum alloy. Process includes careful cleaning, surface preparation, and temperature control. It causes minimum distortion of parts.

  10. Bimetallic non-alloyed NPs for improving the broadband optical absorption of thin amorphous silicon substrates

    PubMed Central

    2014-01-01

    We propose the use of bimetallic non-alloyed nanoparticles (BNNPs) to improve the broadband optical absorption of thin amorphous silicon substrates. Isolated bimetallic NPs with uniform size distribution on glass and silicon are obtained by depositing a 10-nm Au film and annealing it at 600°C; this is followed by an 8-nm Ag film annealed at 400°C. We experimentally demonstrate that the deposition of gold (Au)-silver (Ag) bimetallic non-alloyed NPs (BNNPs) on a thin amorphous silicon (a-Si) film increases the film's average absorption and forward scattering over a broad spectrum, thus significantly reducing its total reflection performance. Experimental results show that Au-Ag BNNPs fabricated on a glass substrate exhibit resonant peaks at 437 and 540 nm and a 14-fold increase in average forward scattering over the wavelength range of 300 to 1,100 nm in comparison with bare glass. When deposited on a 100-nm-thin a-Si film, Au-Ag BNNPs increase the average absorption and forward scattering by 19.6% and 95.9% compared to those values for Au NPs on thin a-Si and plain a-Si without MNPs, respectively, over the 300- to 1,100-nm range. PMID:24725390

  11. PLUTONIUM-URANIUM ALLOY

    DOEpatents

    Coffinberry, A.S.; Schonfeld, F.W.

    1959-09-01

    Pu-U-Fe and Pu-U-Co alloys suitable for use as fuel elements tn fast breeder reactors are described. The advantages of these alloys are ease of fabrication without microcracks, good corrosion restatance, and good resistance to radiation damage. These advantages are secured by limitation of the zeta phase of plutonium in favor of a tetragonal crystal structure of the U/sub 6/Mn type.

  12. Semiconductor Alloy Theory.

    DTIC Science & Technology

    1986-01-14

    ftoc*o~ow7 and Idenify’ by block nam. bor) Electron mobility , Lattice Relaxation, Bond Length, Bond Energy, Mixing Enthalpies, Band Structure, Core...including: (1) generalization of Brooks’ formula for alloy-scattering limited electron mobility to including multiple bands and indirect gaps, (2...calculation of SiGe alloys band structure, electron mobility and core-exciton binding energy and • :linewidth, (3) comprehensive calculation of bond

  13. Continuous roll-to-roll a-Si photovoltaic manufacturing technology

    SciTech Connect

    Izu, M. )

    1993-04-01

    This report describes work performed by ECD to advance its roll-to-roll, triple-junction photovoltaic manufacturing technologies; to reduce the module production costs; to increase the stabilized module performance; and to expand the commercial capacity utilizing ECD technology. The 3-year goal is to develop advanced large-scale manufacturing technology incorporating ECD's earlier research advances with the capability of producing modules with stable 11% efficiency at a cost of approximately $1/W[sub p]. Major efforts during Phase I are (1) the optimization of the high-performance back-reflector system, (2) the optimization of a-Si-Ge narrow band-gap solar cell, and (3) the optimization of the stable efficiency of the module. The goal is to achieve a stable 8% efficient 0.3-m [times] 1.2-m (1-ft [times] 4-ft) module. Also, the efforts include work on a proprietary, high-deposition-rate, microwave plasma, CVD manufacturing technology; and on the investigation of material cost reduction.

  14. Disk Alloy Development

    NASA Technical Reports Server (NTRS)

    Gabb, Tim; Gayda, John; Telesman, Jack

    2001-01-01

    The advanced powder metallurgy disk alloy ME3 was designed using statistical screening and optimization of composition and processing variables in the NASA HSR/EPM disk program to have extended durability at 1150 to 1250 "Fin large disks. Scaled-up disks of this alloy were produced at the conclusion of this program to demonstrate these properties in realistic disk shapes. The objective of the UEET disk program was to assess the mechanical properties of these ME3 disks as functions of temperature, in order to estimate the maximum temperature capabilities of this advanced alloy. Scaled-up disks processed in the HSR/EPM Compressor / Turbine Disk program were sectioned, machined into specimens, and tested in tensile, creep, fatigue, and fatigue crack growth tests by NASA Glenn Research Center, in cooperation with General Electric Engine Company and Pratt & Whitney Aircraft Engines. Additional sub-scale disks and blanks were processed and tested to explore the effects of several processing variations on mechanical properties. Scaled-up disks of an advanced regional disk alloy, Alloy 10, were used to evaluate dual microstructure heat treatments. This allowed demonstration of an improved balance of properties in disks with higher strength and fatigue resistance in the bores and higher creep and dwell fatigue crack growth resistance in the rims. Results indicate the baseline ME3 alloy and process has 1300 to 1350 O F temperature capabilities, dependent on detailed disk and engine design property requirements. Chemistry and process enhancements show promise for further increasing temperature capabilities.

  15. Ultrahigh temperature intermetallic alloys

    SciTech Connect

    Brady, M.P.; Zhu, J.H.; Liu, C.T.; Tortorelli, P.F.; Wright, J.L.; Carmichael, C.A.

    1998-11-01

    A new family of Cr-Cr{sub 2}Ta intermetallic alloys based on Cr-(6--10)Ta (at.%) is under development for structural use in oxidizing environments in the 1,000-1,300 C (1,832--2,372 F) temperature range. Development objectives relate to high temperature strength and oxidation resistance and room temperature fracture toughness. The 1,200 C (2,192 F) strength goals have been met: yield and fracture strengths of 275 MPa (40 ksi) and 345 MPa (50 ksi), respectively, were achieved. Progress in attaining reasonable fracture toughness of Cr-Cr{sub 2}Ta alloys has been made; current alloys exhibit room-temperature values of about 10--12 MPa{radical}m (1.1 MPa{radical}m = 1 ksi{radical}in.). Oxidation rates of these alloys at 950 C (1,742 F) in air are in the range of those reported for chromia-forming alloys. At 1,100 C (2,012 F) in air, chromia volatility was significant but, nevertheless, no scale spallation and positive weight gains of 1--5 mg/cm{sup 2} have been observed during 120-h, 6-cycle oxidation screening tests. These mechanical and oxidative properties represent substantial improvement over Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr alloys previously developed.

  16. Furnace alloys update

    SciTech Connect

    Vervalin, C.H.

    1984-12-01

    The principal share of the cast heat resistant alloy market has long been held by HK-40, a 25Cr/20Ni steel with an average carbon content of 0.40 percent. HK-40 alloy has done a commendable job, especially after its limitations in the various processes were better understood, by designers and operators alike. Presently, and in the future, the materials performance demands of new reformers, ethylene pyrolysis, coal gasification, iron ore reduction and other thermally intensive processes will require alloy capabilities frequently beyond those of HK-40. This article presents an update of the capabilities and limitations of HK-40 and describes a group of higher nickel 25Cr/35Ni alloys of the HP-base, mostly modified by various additions such as columbian, tungsten, titanium, zirconium, cobalt, chromium, molybdenum, silicon and/or aluminum. A number of these alloys are proprietary. Data on the 24Cr/24Ni and 30Cr/30Ni alloys are presented as they have proven, reliable performance at an economical price.

  17. Microstructural Homogeneity and Hot Deformation of Various Friction-Stir-Processed 5083 Al Alloys

    NASA Astrophysics Data System (ADS)

    García-Bernal, M. A.; Mishra, R. S.; Hernández-Silva, D.; Sauce-Rangel, V. M.

    2016-12-01

    Diverse studies on FSP of 5083 Al alloys have been conducted, and some have made comparisons with previous studies of similar alloys, but many times such comparisons could be invalid because of differences in the parameters used during FSP, above all, tool profile. Five 5083 Al alloys produced by different production routes were friction-stir-processed and compared among themselves and with other two superplastic forming (SPF) grade 5083 Al alloys. Results suggest that the grain size refinement is independent of the original microstructure and that there is a relationship between the size of the second phase before and after FSP. The combination of continuous casting 5083 Al alloys + FSP had an outstanding behavior in hot deformation in comparison with rolled or extruded 5083 Al alloys + FSP, and even SPF 5083 Al alloys.

  18. Microstructural Homogeneity and Hot Deformation of Various Friction-Stir-Processed 5083 Al Alloys

    NASA Astrophysics Data System (ADS)

    García-Bernal, M. A.; Mishra, R. S.; Hernández-Silva, D.; Sauce-Rangel, V. M.

    2017-01-01

    Diverse studies on FSP of 5083 Al alloys have been conducted, and some have made comparisons with previous studies of similar alloys, but many times such comparisons could be invalid because of differences in the parameters used during FSP, above all, tool profile. Five 5083 Al alloys produced by different production routes were friction-stir-processed and compared among themselves and with other two superplastic forming (SPF) grade 5083 Al alloys. Results suggest that the grain size refinement is independent of the original microstructure and that there is a relationship between the size of the second phase before and after FSP. The combination of continuous casting 5083 Al alloys + FSP had an outstanding behavior in hot deformation in comparison with rolled or extruded 5083 Al alloys + FSP, and even SPF 5083 Al alloys.

  19. Accelerated decarburization of Fe-C metal alloys

    DOEpatents

    Pal, Uday B.; Sadoway, Donald R.

    1997-01-01

    A process for improving the rate of metal production and FeO utilization in a steelmaking process or a process combining iron-making and steelmaking in a single reactor that uses or generates Fe-C metal alloy droplets submerged in an FeO-containing slag. The process involves discharging a charge build-up (electron accumulation) in the slag at the slag-metal alloy interface by means of an electron conductor connected between the metal alloy droplets and a gas at a gas-slag interface, said gas having an oxygen partial pressure of at least about 0.01 atmosphere.

  20. Accelerated decarburization of Fe-C metal alloys

    DOEpatents

    Pal, U.B.; Sadoway, D.R.

    1997-05-27

    A process is described for improving the rate of metal production and FeO utilization in a steelmaking process or a process combining iron-making and steelmaking in a single reactor that uses or generates Fe-C metal alloy droplets submerged in an FeO-containing slag. The process involves discharging a charge build-up (electron accumulation) in the slag at the slag-metal alloy interface by means of an electron conductor connected between the metal alloy droplets and a gas at a gas-slag interface, said gas having an oxygen partial pressure of at least about 0.01 atmosphere. 2 figs.

  1. Structural properties of a-Si films and their effect on aluminum induced crystallization

    SciTech Connect

    Tankut, Aydin; Ozkol, Engin; Karaman, Mehmet; Turan, Rasit; Canli, Sedat

    2015-10-15

    In this paper, we report the influence of the structural properties of amorphous silicon (a-Si) on its subsequent crystallization behavior via the aluminum induced crystallization (AIC) method. Two distinct a-Si deposition techniques, electron beam evaporation and plasma enhanced chemical vapor deposition (PECVD), are compared for their effect on the overall AIC kinetics as well as the properties of the final poly-crystalline (poly-Si) silicon film. Raman and FTIR spectroscopy results indicate that the PECVD grown a-Si films has higher intermediate-range order, which is enhanced for increased hydrogen dilution during deposition. With increasing intermediate-range order of the a-Si, the rate of AIC is diminished, leading larger poly-Si grain size.

  2. Switching characteristic and capacitance analysis of a-Si:H pinpin photodiodes for visible range telecommunications

    NASA Astrophysics Data System (ADS)

    Fantoni, A.; Fernandes, M.; Louro, P.; Vieira, M.

    2016-05-01

    The device under study is an a-SiC:H/a-Si:H pinpin photodiodes produced by PECVD (Plasma Enhanced Chemical Vapour Deposition) and has a structure that consists of a p-i'(a-SiC:H)-n/p-i(a-Si:H)-n heterostructure with low conductivity doped layers. This device structure has been demonstrated useful in optical communications that use the WDM technique to encode multiple signals in the visible light range. We present in this work experimental results about C-V measurements of the device under complex conditions of illumination. Also it is presented an analysis based on the transient response of the device when illuminated by a pulsed light, with and without optical bias superposition. Rising and decaying times of the collected photocurrent will be outlined under the different conditions. A simulation study outlines the role played by each pin substructure on the response speed and gives some hint on the possible optimization of this device.

  3. Optical emission diagnostics of electron cyclotron resonance and glow discharge plasmas for a-Si:H and a-SiC:H film depositions

    NASA Technical Reports Server (NTRS)

    Yang, C. L.; Shing, Y. H.; Allevato, C. E.

    1988-01-01

    It is demonstrated that the steady-state and kinetic characteristics of ECR (electron cyclotron resonance) and RF glow discharge plasmas can be readily monitored by OES (optical emission spectroscopy) in real time during a-Si:H and a-SiC:H film depositions using an OMA detection system. The ECR and RF glow discharge plasmas used for a-Si:H and a-SiC:H film depositions were studied by monitoring the emission of SiH(asterisk), H(asterisk), H(asterisk)2, and CH(asterisk) excited states. The OES of the ECR plasma shows a strong emission at 434 nm from H(asterisk), which is not detectable in the glow discharge plasma. Steady-state OES studies have established preliminary correlations between SiH(asterisk) and CH(asterisk) emission intensities and the film deposition rate. Transient OES spectra of SiH4 and CH4 plasmas have shown different kinetics in SiH(asterisk) and CH(asterisk) emission intensities. Transient studies of the SiH(asterisk) emission intensity have indicated that additional mechanisms for producing the SiH(asterisk) species become evident in hydrogen-diluted silane plasmas.

  4. Effects of Thermal Exposure on Properties of Al-Li Alloys

    NASA Technical Reports Server (NTRS)

    Shah, Sandeep; Wells, Doug; Stanton, William; Lawless, Kirby; Russell, Carolyn; Wagner, John; Domack, Marcia; Babel, Henry; Farahmand, Bahram; Schwab, David; Jones, Clyde S. (Technical Monitor)

    2002-01-01

    This paper presents viewgraphs on the effects of thermal exposure on the mechanical properties of both developmental and production mature Al-Li alloys. The topics include: 1) Aluminum-Lithium Alloys Composition and Features; 2) Key Characteristics of Al-Li Alloys; 3) Research Approach; 4) Available and Tested Material; and 5) Thermal Exposure Matrix. The alloy temperatures, gage thickness and product forms show that there is no deficit in mechanical properties at lower exposure temperatures in some cases, and a significant deficit in mechanical properties at higher exposure temperatures in all cases.

  5. Effects of Thermal Exposure on Properties of Al-Li Alloys

    NASA Technical Reports Server (NTRS)

    Shah, Sandeep; Wells, Doug; Stanton, William; Lawless, Kirby; Russell, Carolyn; Wagner, John; Domack, Marcia; Babel, Henry; Farahmand, Bahram; Schwab, David; hide

    2002-01-01

    This paper presents viewgraphs on the effects of thermal exposure on the mechanical properties of both developmental and production mature Al-Li alloys. The topics include: 1) Aluminum-Lithium Alloys Composition and Features; 2) Key Characteristics of Al-Li Alloys; 3) Research Approach; 4) Available and Tested Material; and 5) Thermal Exposure Matrix. The alloy temperatures, gage thickness and product forms show that there is no deficit in mechanical properties at lower exposure temperatures in some cases, and a significant deficit in mechanical properties at higher exposure temperatures in all cases.

  6. Analytic model of nanoparticle formation and growth in a SiH4-Ar plasma

    NASA Astrophysics Data System (ADS)

    Gordiets, B. F.; Bertran, E.

    2009-05-01

    A kinetic model of formation and growth of nanoparticles in a low-pressure plasma-chemical reactor with an rf capacitive discharge in a SiH4-Ar mixture is presented. Analytic formulas are derived for calculating the concentration of monomers, as well as the concentration and average size of nanoparticles. The results are compared with the results of numerical calculations and experimental data for nanoparticles in a SiH4-Ar plasma.

  7. The residual voltage in fast electrophotography of a-SiH/x/

    NASA Astrophysics Data System (ADS)

    Oda, S.; Terazono, S.-I.; Shimizu, I.

    1982-11-01

    The space charge distribution in a-SiH(x) photoreceptors is investigated by measurement of the residual voltage in xerographic photodischarge characteristics. The correlation between boron concentrations in the a-SiH(x) photoreceptor and the residual voltage is evaluated. It is found that the space charge is localized within 5000 A of the interface, and that the residual voltage can be eliminated by a proper choice of the boron concentration and of the wavelength of the exciting light.

  8. Thermal stability of hydrogen and sulfur atoms in a-SiSx:H films

    NASA Astrophysics Data System (ADS)

    Itoh, Takashi; Nitta, Shoji; Wang, S. L.; Taylor, P. C.

    1996-11-01

    The thermal stability of hydrogen and sulfur atoms in a-SiSx:H films is studied using gas effusion spectra and electron spectroscopy for chemical analysis. Two evolution peaks of hydrogen are found above 400 °C in gas effusion spectra of a-SiSx:H films. Sulfur atoms are evolved only above 550 °C. The stability of sulfur and the relationship of dangling bonds to sulfur effusion are discussed.

  9. Photocapacitance and hole drift mobility measurements in hydrogenated amorphous silicon (a-Si:H)

    SciTech Connect

    Nurdjaja, I.; Schiff, E.A.

    1997-07-01

    The authors present measurements of the photocapacitance in hydrogenated amorphous silicon (a-Si:H) Schottky barrier diodes under reverse bias. A calculation relating photocapacitance to hole drift mobility measurements is also presented; the calculation incorporates the prominent dispersion effect for holes in a-Si:H usually attributed to valence bandtail trapping. The calculation accounts quantitatively for the magnitude and voltage-dependence of the photocapacitance.

  10. Laser Peening of Alloy 22 Welds

    SciTech Connect

    Stevens, D W; Hackel, L A; Lingenfelter, A C

    2002-10-03

    Stress corrosion cracking (SCC) of near-surface Alloy 22 metal can be propagated by yield-point levels (45 ksi) of residual weld tensile stresses. This is a serious concern for welds in the Alloy 22 canister employed in the Yucca Mountain Project (YMP) Waste Package, particularly in closure welds that cannot be stress relieved by conventional heat treating. This work shows that compressive shock waves, driven into a weldment by laser peening, replaces its detrimental tensile stresses of 30-80 ksi with compressive stresses of 2-25 ksi or better that retard SCC. This benefit occurs in the top 1.5 mm (or more) of the material without appreciable heating. It was also found that quenching after solution annealing and shot peening during production of Alloy 22 plate imparts compressive stresses of 35-105 ksi near the surface, a very large buffer against SCC. This means that if seam-welded hollow canisters likewise gain compressive stresses upon post-weld annealing and quenching, and if closure welds are laser peened, all surfaces of the canister would be under compression, thereby precluding SCC of the Alloy 22 canister. Laser peening may plastically deform as much as the top 10% of the metal (about 2 mm out of the 25-mm plate thickness), thereby changing the rate of general corrosion of waste package outer barrier. Long-term corrosion tests of laser peened Alloy 22 welds should be conducted. Present results show that laser peening, currently under development at LLNL using high-energy lasers, induces compressive residual stress on the near surface of the weld. This laser peening process is showing significant retardation of SCC and should be further characterized and assessed to preclude SCC in Alloy 22 canisters.

  11. Method and apparatus for production of powders

    NASA Technical Reports Server (NTRS)

    Stolzfus, Joel M. (Inventor); Sircar, Subhasish (Inventor)

    1995-01-01

    Apparatus and method are disclosed for producing oxides of metals and of metal alloys. The metal or alloy is placed in an oxygen atmosphere in a combustion chamber and ignited. Products of the combustion include one or more oxides of the metal or alloy in powdered form. In one embodiment of the invention a feeder is provided whereby material to be oxidized by combustion can be advanced into a combustion chamber continuously. A product remover receives the powder product of the combustion.

  12. Method and Apparatus for Production of Powders

    NASA Technical Reports Server (NTRS)

    Storltzfus, Joel M. (Inventor); Sircar, Subhasish (Inventor)

    1998-01-01

    Apparatus and method are disclosed for producing oxides of metals and of metal alloys. The metal or alloy is placed in an oxygen atmosphere in a combustion chamber and ignited. Products of the combustion include one or more oxides of the metal or alloy in powdered form. In one embodiment of the invention a feeder is provided whereby material to be oxidized by combustion can be advanced into a combustion chamber continuously. A product remover receives the powder product of the combustion.

  13. Preparation of Fe-Ni-Based Metal-Metalloid Amorphous Alloys by Mechanical Alloying and Mechanical Grinding Methods

    NASA Astrophysics Data System (ADS)

    Miura, Harumatsu; Isa, Shigeteru; Omuro, Keisuke

    1990-02-01

    Using a high energy ball mill, alloys of Fe40Ni40P14B6 and Fe40Ni40B20 were synthesized from crystalline, elemental iron and nickel metals and iron-metalloid alloys such as Fe-B and Fe-P by mechanical alloying (MA). Powders of the Fe40Ni40P14B6 alloy were also prepared from the cast ingot products by mechanical grinding (MG). Each of the MA and MG powder products showed a halo pattern typical of amorphous materials in the X-ray diffraction trace, and the crystallization enthalpy of the Fe40Ni40P14B6 MA powder, measured by differential scanning calorimetry, was almost the same as that of the melt-quenched sample of the same composition.

  14. Optimized spacer layer thickness for plasmonic-induced enhancement of photocurrent in a-Si:H

    NASA Astrophysics Data System (ADS)

    Saleh, Z. M.; Nasser, H.; Özkol, E.; Günöven, M.; Abak, K.; Canli, S.; Bek, A.; Turan, R.

    2015-10-01

    Plasmonic interfaces consisting of silver nanoparticles of different sizes (50-100 nm) have been processed by the self-assembled dewetting technique and integrated to hydrogenated amorphous silicon (a-Si:H) using SiN x spacer layers to investigate the dependence of optical trapping enhancement on spacer layer thickness through the enhancements in photocurrent. Samples illuminated from the a-Si:H side exhibit a localized surface plasmon resonance (LSPR) that is red-shifted with the increasing particle size and broadened into the red with the increasing spacer layer thickness. The photocurrent measured in a-Si:H is not only consistent with the red-shift and broadening of the LSPR, but exhibits critical dependence on the spacer layer thickness also. The samples with plasmonic interfaces and a SiN x spacer layer exhibit appreciable enhancement of photocurrent compared with flat a-Si:H reference depending on the size of the Ag nanoparticle. Simulations conducted on one-dimensional square structures exhibit electric fields that are localized near the plasmonic structures but extend appreciably into the higher refractive index a-Si:H. These simulations produce a clear red-shift and broadening of extinction spectra for all spacer layer thicknesses and predict an enhancement in photocurrent in agreement with experimental results. The spectral dependence of photocurrent for six plasmonic interfaces with different Ag nanoparticle sizes and spacer layer thicknesses are correlated with the optical spectra and compared with the simulations to predict an optimal spacer layer thickness.

  15. Hot Microfissuring in Nickel Alloy

    NASA Technical Reports Server (NTRS)

    Thompson, R. G.; Nunes, A.

    1984-01-01

    Experiments in intergranular cracking of nickel alloy near solidus temperature discussed in contractor report. Purpose of investigation development of schedule for welding, casting, forging, or other processing of alloy without causing microfissuring.

  16. Hot Microfissuring in Nickel Alloy

    NASA Technical Reports Server (NTRS)

    Thompson, R. G.; Nunes, A.

    1984-01-01

    Experiments in intergranular cracking of nickel alloy near solidus temperature discussed in contractor report. Purpose of investigation development of schedule for welding, casting, forging, or other processing of alloy without causing microfissuring.

  17. Equal-Channel Angular Extrusion of a Low-Density High-Entropy Alloy Produced by High-Energy Cryogenic Mechanical Alloying

    NASA Astrophysics Data System (ADS)

    Hammond, Vincent H.; Atwater, Mark A.; Darling, Kristopher A.; Nguyen, Hoang Q.; Kecskes, Laszlo J.

    2014-10-01

    In this study, we demonstrate the feasibility of forming a bulk consolidated, low-density high-entropy alloy, namely AlFeMgTiZn, which shows reasonable mechanical properties and high hardness. The fabrication of the high-entropy alloy from powdered precursors via high-energy mechanical alloying as a function of milling time is presented. In turn, the evolution of the alloy microstructure with postmilling anneal treatment is elucidated. Last, the severe plastic deformation processing methodology, i.e., equal-channel angular extrusion, chosen for consolidation, is described and shown to result in a bulk product with good results.

  18. A Si(0.7)Ge(0.3) strained-layer etch stop for the generation of thin layer undoped silicon

    NASA Astrophysics Data System (ADS)

    Godbey, D.; Hughes, H.; Kub, F.; Twigg, M.; Palkuti, L.

    1990-01-01

    A system is described which makes it possible to fabricate a defect-free thin-film silicon-on-insulator substrate using a Si-Ge strained layer as an etch stop. In this process, a 60-nm-thick strained-layer Si(0.7)Ge(0.3) alloy is grown on a silicon substrate, followed by a silicon cap (which is the region where devices will be built). The etch rate through undoped silicon was measured to be 17-20 nm/min, while the etch rate through the Si(0.7)Ge(0.3) layer was 1 nm/min. After annealing the wafer at 850 C for 30 min, the etch rate through the strained layer increased to 1.7 nm/min, and the strained layer was still perfectly functional as an etch stop. A TEM examination of the annealed wafer showed that the strain in the alloy was only partially relieved and that the generated misfit dislocations were confined to the strained layer.

  19. Aluminum Alloy 7068 Mechanical Characterization

    DTIC Science & Technology

    2009-08-01

    strength of 99 ksi (2). The commonly specified material properties for extruded 7068 aluminum are shown in table 1, along with 7050 and 7075 aluminum ...alloys for comparison (3). Table 1. Mechanical property comparison of high-strength aluminum alloys. Property Alloy 7068 7075 7050 Elastic... Aluminum Alloy 7068 Mechanical Characterization by Michael Minnicino, David Gray, and Paul Moy ARL-TR-4913 August 2009

  20. Selective dissolution in binary alloys

    NASA Astrophysics Data System (ADS)

    McCall, Carol Rene

    Corrosion is an important issue in the design of engineering alloys. De-alloying is an aspect of alloy corrosion related to the selective dissolution of one or more of the components in an alloy. The work reported herein focuses on the topic of de-alloying specific to single-phase binary noble metal alloy systems. The alloy systems investigated were gold-silver and gold-copper. The onset of a bulk selective dissolution process is typically marked by a critical potential whereby the more reactive component in the alloy begins dissolving from the bulk, leading to the formation of a bi-continuous solid-void morphology. The critical potential was investigated for the entire composition range of gold-silver alloys. The results presented herein include the formulation of an expression for critical potential as a function of both alloy and electrolyte composition. Results of the first investigation of underpotential deposition (UPD) on alloys are also presented herein. These results were implemented as an analytical tool to provide quantitative measurements of the surface evolution of gold during de-alloying. The region below the critical potential was investigated in terms of the compositional evolution of the alloy surface. Below the critical potential, there is a competition between the dissolution of the more reactive alloying constituent (either silver or copper) and surface diffusion of gold that serves to cover dissolution sites and prevent bulk dissolution. By holding the potential at a prescribed value below the critical potential, a time-dependent gold enrichment occurs on the alloy surface leading to passivation. A theoretical model was developed to predict the surface enrichment of gold based on the assumption of layer-by-layer dissolution of the more reactive alloy constituent. The UPD measurements were used to measure the time-dependent surface gold concentration and the results agreed with the predictions of the theoretical model.

  1. Studies on effective atomic numbers, electron densities and mass attenuation coefficients in Au alloys.

    PubMed

    Han, I; Demir, L

    2010-01-01

    The total mass attenuation coefficients (mu/rho) for pure Au and Au99Be1, Au88Ge12, Au95Zn5 alloys were measured at 59.5 and 88.0 keV photon energies. The samples were irradiated with 241Am and 109Cd radioactive point source using transmission arrangement. The gamma- rays were counted by a Si(Li) detector with resolution of 160 eV at 5.9 keV. Total atomic and electronic cross-sections (sigmat and sigmae), effective atomic and electron densities (Zeff and Nel) were determined using the obtained mass attenuation coefficients for investigated Au alloys. The theoretical mass attenuation coefficients of each alloy were estimated using mixture rule.

  2. Tissue Response to Base-Metal Dental Alloys.

    DTIC Science & Technology

    RESPONSE(BIOLOGY), *CASTING ALLOYS, *BASE METAL, * DENTAL PROSTHESES, TISSUES(BIOLOGY), COMPATIBILITY, NICKEL ALLOYS, BERYLLIUM, DENTISTRY, CANCER, HISTOLOGY, DENTAL IMPLANTOLOGY , COBALT ALLOYS, CHROMIUM ALLOYS.

  3. Metastability of a-SiOx:H thin films for c-Si surface passivation

    NASA Astrophysics Data System (ADS)

    Serenelli, L.; Martini, L.; Imbimbo, L.; Asquini, R.; Menchini, F.; Izzi, M.; Tucci, M.

    2017-01-01

    The adoption of a-SiOx:H films obtained by PECVD in heterojunction solar cells is a key to further increase their efficiency, because of its transparency in the UV with respect to the commonly used a-Si:H. At the same time this layer must guarantee high surface passivation of the c-Si to be suitable in high efficiency solar cell manufacturing. On the other hand the application of amorphous materials like a-Si:H and SiNx on the cell frontside expose them to the mostly energetic part of the sun spectrum, leading to a metastability of their passivation properties. Moreover as for amorphous silicon, thermal annealing procedures are considered as valuable steps to enhance and stabilize thin film properties, when performed at opportune temperature. In this work we explored the reliability of a-SiOx:H thin film layers surface passivation on c-Si substrates under UV exposition, in combination with thermal annealing steps. Both p- and n-type doped c-Si substrates were considered. To understand the effect of UV light soaking we monitored the minority carriers lifetime and Sisbnd H and Sisbnd O bonding, by FTIR spectra, after different exposure times to light coming from a deuterium lamp, filtered to UV-A region, and focused on the sample to obtain a power density of 50 μW/cm2. We found a certain lifetime decrease after UV light soaking in both p- and n-type c-Si passivated wafers according to a a-SiOx:H/c-Si/a-SiOx:H structure. The role of a thermal annealing, which usually enhances the as-deposited SiOx passivation properties, was furthermore considered. In particular we monitored the UV light soaking effect on c-Si wafers after a-SiOx:H coating by PECVD and after a thermal annealing treatment at 300 °C for 30 min, having selected these conditions on the basis of the study of the effect due to different temperatures and durations. We correlated the lifetime evolution and the metastability effect of thermal annealing to the a-SiOx:H/c-Si interface considering the evolution

  4. Finding the Alloy Genome

    NASA Astrophysics Data System (ADS)

    Hart, Gus L. W.; Nelson, Lance J.; Zhou, Fei; Ozolins, Vidvuds

    2012-10-01

    First-principles codes can nowadays provide hundreds of high-fidelity enthalpies on thousands of alloy systems with a modest investment of a few tens of millions of CPU hours. But a mere database of enthalpies provides only the starting point for uncovering the ``alloy genome.'' What one needs to fundamentally change alloy discovery and design are complete searches over candidate structures (not just hundreds of known experimental phases) and models that can be used to simulate both kinetics and thermodynamics. Despite more than a decade of effort by many groups, developing robust models for these simulations is still a human-time-intensive endeavor. Compressive sensing solves this problem in dramatic fashion by automatically extracting the ``sparse model'' of an alloy in only minutes. This new paradigm to model building has enabled a new framework that will uncover, automatically and in a general way across the periodic table, the important components of such models and reveal the underlying ``genome'' of alloy physics.

  5. Titanium by design: TRIP titanium alloy

    NASA Astrophysics Data System (ADS)

    Tran, Jamie

    Motivated by the prospect of lower cost Ti production processes, new directions in Ti alloy design were explored for naval and automotive applications. Building on the experience of the Steel Research Group at Northwestern University, an analogous design process was taken with titanium. As a new project, essential kinetic databases and models were developed for the design process and used to create a prototype design. Diffusion kinetic models were developed to predict the change in phase compositions and microstructure during heat treatment. Combining a mobility database created in this research with a licensed thermodynamic database, ThermoCalc and DICTRA software was used to model kinetic compositional changes in titanium alloys. Experimental diffusion couples were created and compared to DICTRA simulations to refine mobility parameters in the titanium mobility database. The software and database were able to predict homogenization times and the beta→alpha plate thickening kinetics during cooling in the near-alpha Ti5111 alloy. The results of these models were compared to LEAP microanalysis and found to be in reasonable agreement. Powder metallurgy was explored using SPS at GM R&D to reduce the cost of titanium alloys. Fully dense Ti5111 alloys were produced and achieved similar microstructures to wrought Ti5111. High levels of oxygen in these alloys increased the strength while reducing the ductility. Preliminary Ti5111+Y alloys were created, where yttrium additions successfully gettered excess oxygen to create oxides. However, undesirable large oxides formed, indicating more research is needed into the homogeneous distribution of the yttrium powder to create finer oxides. Principles established in steels were used to optimize the beta phase transformation stability for martensite transformation toughening in titanium alloys. The Olson-Cohen kinetic model is calibrated to shear strains in titanium. A frictional work database is established for common alloying

  6. Diffusion bonding of aluminium alloy, 8090

    SciTech Connect

    Sunwoo, A. )

    1994-08-15

    Ability to diffusion bond aluminum (Al) alloys, in particular superplastic aluminum alloys, will complete the technology-base that is strongly needed to enhance the use of superplastic forming (SPF) technology. Diffusion bonding (DB) is an attractive manufacturing option for applications where the preservation of the base metal microstructure and, in turn, mechanical properties is important in the bond area. As the technology moves from the laboratory to production, the DB process has to be production-feasible and cost-effective. At the Lawrence Livermore National Laboratory, the DB study of SPF Al alloys has been initiated. This paper describes the effect of surface chemistry on the DB properties of the Al alloy, 8090 (2.4Li-1.18Cu-0.57Mg-0.14Zr-Al). The integrity of the diffusion bonds was evaluated for both interlayered and bare surfaces. Two interlayer elements, copper (Cu) and zinc (Zn), were compared. Although the eutectic temperature of Al-Cu is 548 C, a thin Cu layer in contact with 8090 has been shown to lower its eutectic temperature to [approximately]521 C. In 8090, Cu is one of the primary alloying elements but has a limited solubility in Al at the bonding temperature. Zinc, on the other hand, forms a considerably lower eutectic (380 C) with Al and is highly soluble in Al. The diffusivity of Zn in Al is much faster than that of Cu, but Zn forms a more thermodynamically stable oxide. These subtle metallurgical differences will affect the transient liquid phase (TLP) formation at the interface, which will subsequently influence the bond quality.

  7. PLUTONIUM-URANIUM-TITANIUM ALLOYS

    DOEpatents

    Coffinberry, A.S.

    1959-07-28

    A plutonium-uranium alloy suitable for use as the fuel element in a fast breeder reactor is described. The alloy contains from 15 to 60 at.% titanium with the remainder uranium and plutonium in a specific ratio, thereby limiting the undesirable zeta phase and rendering the alloy relatively resistant to corrosion and giving it the essential characteristic of good mechanical workability.

  8. De-alloyed platinum nanoparticles

    DOEpatents

    Strasser, Peter; Koh, Shirlaine; Mani, Prasanna; Ratndeep, Srivastava

    2011-08-09

    A method of producing de-alloyed nanoparticles. In an embodiment, the method comprises admixing metal precursors, freeze-drying, annealing, and de-alloying the nanoparticles in situ. Further, in an embodiment de-alloyed nanoparticle formed by the method, wherein the nanoparticle further comprises a core-shell arrangement. The nanoparticle is suitable for electrocatalytic processes and devices.

  9. Aluminum alloys with improved strength

    NASA Technical Reports Server (NTRS)

    Deiasi, R.; Adler, P.

    1975-01-01

    Mechanical strength and stress corrosion of new BAR and 7050 alloys that include Zn instead of Cr have been studied and compared with those of 7075 aluminum alloy. Added mechanical strength of new alloys is attributed to finer grain size of 5 to 8 micrometers, however, susceptibility to stress corrosion attack is increased.

  10. Semiconductor alloys - Structural property engineering

    NASA Technical Reports Server (NTRS)

    Sher, A.; Van Schilfgaarde, M.; Berding, M.; Chen, A.-B.

    1987-01-01

    Semiconductor alloys have been used for years to tune band gaps and average bond lengths to specific applications. Other selection criteria for alloy composition, and a growth technique designed to modify their structural properties, are presently considered. The alloys Zn(1-y)Cd(y)Te and CdSe(y)Te(1-y) are treated as examples.

  11. Semiconductor alloys - Structural property engineering

    NASA Technical Reports Server (NTRS)

    Sher, A.; Van Schilfgaarde, M.; Berding, M.; Chen, A.-B.

    1987-01-01

    Semiconductor alloys have been used for years to tune band gaps and average bond lengths to specific applications. Other selection criteria for alloy composition, and a growth technique designed to modify their structural properties, are presently considered. The alloys Zn(1-y)Cd(y)Te and CdSe(y)Te(1-y) are treated as examples.

  12. Recent advances in the synthesis of alloy phases by mechanical alloying/milling

    NASA Astrophysics Data System (ADS)

    Suryanarayana, C.

    1996-08-01

    Mechanical alloying (MA) is a solid-state powder processing technique involving repeated welding, fracturing, and rewelding of powder particles in a high-energy ball mill. Originally developed to produce oxide-dispersion strengthened nickel- and iron-base superalloys, MA has now been shown to be capable of synthesizing a number of alloy phases—equilibrium and supersaturated solid solutions, stable and metastable crystalline and quasicrystalline intermediate phases, and amorphous alloys. Recent advances in these areas and also on disordering of ordered intermetallics and displacement reactions have been critically reviewed. Wherever possible, comparisons have been made on the product phases obtained by MA and by rapid solidification processing, another non-equilibrium processing technique.

  13. The microstructure and superplastic behavior of clean mechanically alloyed titanium - titanium boride alloys

    SciTech Connect

    Brown, A.P.; Brydson, R.; Hammond, C.; Wisbey, A.; Godfrey, T.M.T.

    2000-07-01

    The superplastic forming (SPF) of titanium alloys is an established technology. A reduction in grain size from that of the typical sheet materials would lead to enhanced SPF properties and hence a reduction in production cycle times. This study describes the microstructural development and superplastic behavior of fine-grained Ti-6%Al-4%V alloys. Ball-milling Ti-6%Al-4%V powder produces a nanocrystalline material; however on consolidation by hot isostatic pressing rapid grain growth occurs. Addition of boron powder during milling leads to boride precipitates in the matrix of the consolidated alloy. The precipitates are dispersed inhomogeneously, resulting in localized grain refinement. Superplastic testing revealed cavitation formation but in comparison to conventional sheet material, large elongations were achieved at relatively high strain rates.

  14. Glassy Metal Alloy Nanofiber Anodes Employing Graphene Wrapping Layer: Toward Ultralong-Cycle-Life Lithium-Ion Batteries.

    PubMed

    Jung, Ji-Won; Ryu, Won-Hee; Shin, Jungwoo; Park, Kyusung; Kim, Il-Doo

    2015-07-28

    Amorphous silicon (a-Si) has been intensively explored as one of the most attractive candidates for high-capacity and long-cycle-life anode in Li-ion batteries (LIBs) primarily because of its reduced volume expansion characteristic (∼280%) compared to crystalline Si anodes (∼400%) after full Li(+) insertion. Here, we report one-dimensional (1-D) electrospun Si-based metallic glass alloy nanofibers (NFs) with an optimized composition of Si60Sn12Ce18Fe5Al3Ti2. On the basis of careful compositional tailoring of Si alloy NFs, we found that Ce plays the most important role as a glass former in the formation of the metallic glass alloy. Moreover, Si-based metallic glass alloy NFs were wrapped by reduced graphene oxide sheets (specifically Si60Sn12Ce18Fe5Al3Ti2 NFs@rGO), which can prevent the direct exposure of a-Si alloy NFs to the liquid electrolyte and stabilize the solid-electrolyte interphase (SEI) layers on the surfaces of rGO sheets while facilitating electron transport. The metallic glass nanofibers exhibited superior electrochemical cell performance as an anode: (i) Si60Sn12Ce18Fe5Al3Ti2 NFs show a high specific capacity of 1017 mAh g(-1) up to 400 cycles at 0.05C with negligible capacity loss as well as superior cycling performance (nearly 99.9% capacity retention even after 2000 cycles at 0.5C); (ii) Si60Sn12Ce18Fe5Al3Ti2 NFs@rGO reveals outstanding rate behavior (569.77 mAh g(-1) after 2000 cycles at 0.5C and a reversible capacity of around 370 mAh g(-1) at 4C). We demonstrate the potential suitability of multicomponent a-Si alloy NFs as a long-cycling anode material.

  15. Study of hydrogen states in a-Si:H films, dehydrogenization treatments and influence of hydrogen on nanosecond pulse laser crystallization of a-Si:H

    NASA Astrophysics Data System (ADS)

    Volodin, V. A.; Galkov, M. S.; Safronova, N. A.; Kamaev, G. N.; Antonenko, A. H.; Kochubey, S. A.

    2014-12-01

    Structures based on hydrogenated amorphous silicon (a-Si:H) films deposited on various substrates (including not refractory ones) are widely applied in giant microelectronics devices, such as flat panel displays based on active matrix thin-film transistors and solar cells. The a-Si:H films produced by plasma enhanced chemical vapor deposition (PECVD) methods, contain up to 40% atoms of hydrogen. The influence of hydrogen on the optical and electrical properties of the films and their degradation is important. Therefore, the development of express and non-destructive methods for control of the hydrogen concentration in thin films continues to be an actual task to date. Previously, from a comparative analysis of infrared (IR) spectroscopy and Raman scattering spectroscopy, the ratios of the integral intensities of Raman peaks due to scattering by vibrations of the Si-H and Si-H2 bonds to the intensity of Raman peak of the Si-Si bonds were experimentally determined. Knowing these ratios, it is possible to measure the hydrogen concentration, moreover, separately in Si-H and Si-H2 states. Proposed quantitative method for determining of the hydrogen concentration from analysis of the Raman spectra is an express, non-destructive method and can be used for "in situ" monitoring of the hydrogen. The aim of this work was to determine the polarization dependence of Raman scattering by stretching vibrations of Si-H bonds and find the form of the corresponding Raman tensors. From analysis of Raman intensities in different polarizations the Raman tensors for Si-H and Si-H2 bonds were determined. The regimes for dehydrogenization of thick (up to 1 micron) a-Si:H films were found. The nanosecond pulse XeCl laser with wavelength of 308 nm and pulse duration of 10 ns was used for pulse crystallization of as-deposited and dehydrogenated films. As it was studied earlier, for a-Si:H films with high hydrogen concentration, the threshold for crystallization is very close to threshold of

  16. Deriving the Metal and Alloy Networks of Modern Technology.

    PubMed

    Ohno, Hajime; Nuss, Philip; Chen, Wei-Qiang; Graedel, Thomas E

    2016-04-05

    Metals have strongly contributed to the development of the human society. Today, large amounts of and various metals are utilized in a wide variety of products. Metals are rarely used individually but mostly together with other metals in the form of alloys and/or other combinational uses. This study reveals the intersectoral flows of metals by means of input-output (IO) based material flow analysis (MFA). Using the 2007 United States IO table, we calculate the flows of eight metals (i.e., manganese, chromium, nickel, molybdenum, niobium, vanadium, tungsten, and cobalt) and simultaneously visualize them as a network. We quantify the interrelationship of metals by means of flow path sharing. Furthermore, by looking at the flows of alloys into metal networks, the networks of the major metals iron, aluminum, and copper together with those of the eight alloying metals can be categorized into alloyed-, nonalloyed-(i.e., individual), and both mixed. The result shows that most metals are used primarily in alloy form and that functional recycling thereby requires identification, separation, and alloy-specific reprocessing if the physical properties of the alloys are to be retained for subsequent use. The quantified interrelation of metals helps us consider better metal uses and develop a sustainable cycle of metals.

  17. Productivity

    Treesearch

    Thomas R. Fox; Ray R. Hicks

    2004-01-01

    The South is blessed with abundant and diverse forest resources. Today, forests cover approximately 215 million acres in the South, which represents 29 percent of the forest land in the United States (Conner and Hartsell 2002). Maintaining the productivity of these forests is essential to the economic, environmental, and social well being of the South and the Nation....

  18. Nanocrystalline SiC and Ti3SiC2 Alloys for Reactor Materials: Diffusion of Fission Product Surrogates

    SciTech Connect

    Henager, Charles H.; Jiang, Weilin

    2014-11-01

    MAX phases, such as titanium silicon carbide (Ti3SiC2), have a unique combination of both metallic and ceramic properties, which make them attractive for potential nuclear applications. Ti3SiC2 has been suggested in the literature as a possible fuel cladding material. Prior to the application, it is necessary to investigate diffusivities of fission products in the ternary compound at elevated temperatures. This study attempts to obtain relevant data and make an initial assessment for Ti3SiC2. Ion implantation was used to introduce fission product surrogates (Ag and Cs) and a noble metal (Au) in Ti3SiC2, SiC, and a dual-phase nanocomposite of Ti3SiC2/SiC synthesized at PNNL. Thermal annealing and in-situ Rutherford backscattering spectrometry (RBS) were employed to study the diffusivity of the various implanted species in the materials. In-situ RBS study of Ti3SiC2 implanted with Au ions at various temperatures was also performed. The experimental results indicate that the implanted Ag in SiC is immobile up to the highest temperature (1273 K) applied in this study; in contrast, significant out-diffusion of both Ag and Au in MAX phase Ti3SiC2 occurs during ion implantation at 873 K. Cs in Ti3SiC2 is found to diffuse during post-irradiation annealing at 973 K, and noticeable Cs release from the sample is observed. This study may suggest caution in using Ti3SiC2 as a fuel cladding material for advanced nuclear reactors operating at very high temperatures. Further studies of the related materials are recommended.

  19. Application of a-Si:H radiation detectors in medical imaging

    SciTech Connect

    Lee, Hyoung-Koo

    1995-06-01

    Monte Carlo simulations of a proposed a-Si:H-based current-integrating gamma camera were performed. The analysis showed that the intrinsic resolution of such a camera was 1 ~2.5 mm, which is somewhat better than that of a conventional gamma camera, and that the greater blurring, due to the detection of scattered γ-rays, could be reduced considerably by image restoration techniques. This proposed gamma camera would be useful for imaging shallow organs such as the thyroid. Prototype charge-storage a-Si:H pixel detectors for such a camera were designed, constructed and tested. The detectors could store signal charge as long as 5 min at -26C. The thermal generation current in reverse biased a-Si:H p-i-n photodetectors was investigated, and the Poole-Frenkel effect was found to be the most significant source of the thermal generation current. Based on the Poole-Frenkel effect, voltage- and time-dependent thermal generation current was modeled. Using the model, the operating conditions of the proposed a-Si:H gamma camera, such as the operating temperature, the operating bias and the γ-scan period, could be predicted. The transient photoconductive gain mechanism in various a-Si:H devices was investigated for applications in digital radiography. Using the a-Si:H photoconductors in n-i-n configuration in pixel arrays, enhancement in signal collection (more than 200 times higher signal level) can be achieved in digital radiography, compared to the ordinary p-i-n type a-Si:H x-ray imaging arrays.

  20. Hydrogen in titanium alloys

    SciTech Connect

    Wille, G W; Davis, J W

    1981-04-01

    The titanium alloys that offer properties worthy of consideration for fusion reactors are Ti-6Al-4V, Ti-6Al-2Sn-4Zr-2Mo-Si (Ti-6242S) and Ti-5Al-6Sn-2Zr-1Mo-Si (Ti-5621S). The Ti-6242S and Ti-5621S are being considered because of their high creep resistance at elevated temperatures of 500/sup 0/C. Also, irradiation tests on these alloys have shown irradiation creep properties comparable to 20% cold worked 316 stainless steel. These alloys would be susceptible to slow strain rate embrittlement if sufficient hydrogen concentrations are obtained. Concentrations greater than 250 to 500 wppm hydrogen and temperatures lower than 100 to 150/sup 0/C are approximate threshold conditions for detrimental effects on tensile properties. Indications are that at the elevated temperature - low hydrogen pressure conditions of the reactors, there would be negligible hydrogen embrittlement.

  1. The influence of a Si cap on self-organized SiGe islands and the underlying wetting layer

    SciTech Connect

    Brehm, M.; Grydlik, M.; Groiss, H.; Hackl, F.; Schaeffler, F.; Fromherz, T.; Bauer, G.

    2011-06-15

    For the prototypical SiGe/Si(001) Stranski-Krastanow (SK) growth system, the influence of intermixing caused by the deposition of a Si cap layer at temperatures T{sub cap} between 300 deg. C and 700 deg. C is studied both for the SiGe wetting layer (WL) and the SiGe islands. Systematic growth experiments were carried out with an ultrahigh resolution of down to 0.005 monolayers (ML) of deposited Ge. The properties of the samples were investigated via photoluminescence (PL) spectroscopy, atomic force microscopy (AFM), and transmission electron microscopy. We studied in detail the influence of T{sub cap} in the three main coverage regions of SiGe SK growth, which are (i) the WL build-up regime, (ii) the island nucleation regime, where most of the Ge is supplied via material transfer from the WL, and (iii) the saturation regime, where the WL thickness remains initially stable. At T{sub cap} = 300 deg. C, we found that both the WL and the island are essentially preserved in composition and shape, whereas at 500 deg. C the WL becomes heavily alloyed during capping, and at 700 deg. C the islands also become alloyed. At T{sub cap} = 500 deg. C we found enhanced WL intermixing in the presence of dome-shaped islands, whereas at T{sub cap} 700 deg. C the WL properties become dominated by the dissolution of pyramid-shaped islands upon capping. At Ge coverages above {approx_equal}6 ML, we found an unexpected thickening of the WL, almost independently of T{sub cap}. This finding suggests that the density and the volume of the dome-shaped islands have an upper limit, beyond which excess Ge from the external source again becomes incorporated into the WL. Finally, we compared PL spectra with AFM-based evaluations of the integral island volumes in order to determine in a straightforward manner the average composition of the SiGe islands.

  2. Dendritic growth in a supercooled alloy melt

    NASA Technical Reports Server (NTRS)

    Laxmanan, V.

    1987-01-01

    A simple model which describes the growth of an 'array' of dendrites into a supercooled, binary, alloy melt is presented. Solute diffusion is calculated by superposing the solutions given by Flemings and Zener, and also, by superposing the solutions given by Ivantsov and Flemings. A general expression for the transport solution is suggested from which all other dendrite growth models presented earlier may be obtained as special cases. It is shown that both 'free' and 'constrained' growth may be described by a single transport solution, which indicates that (1) both thermal and solutal effects will be important during 'free' growth in dilute alloys, (2) only solutal effects are predominant during 'free' growth in concentrated alloys and during 'constrained' growth. An examination of the relevant dimensionless parameters also suggests that all dendrite growth models, regardless of the assumptions used to determine the tip radius (marginal stability, minimum undercooling, maximum velocity, minimum entropy production) should predict the experimentally observed extrema in tip radius and growth velocity in dilute alloys, during 'free' dendritic growth. Experimental data in binary H2O-NaCl and succinonitrile-acetone solutions are shown to be in good agreement with the model.

  3. Gas-deposit-alloy corrosion interactions in simulated combustion environments

    NASA Astrophysics Data System (ADS)

    Luer, Kevin Raymond

    High temperature corrosion in aggressive coal combustion environments involves simultaneous corrosion reactions between combustion gases, ash deposits, and alloys. This research investigated the behavior of a ferritic steel (SA387-Gr11) and three weld claddings (309L SS, Alloy 72, and Alloy 622) in five combustion environments beneath solid deposits at 500°C for up to 1000 hours. The synthetic gases consisted of N2-CO-CO-H2-H2O-H 2S-SO2 mixtures that simulated a range of fuel-rich or fuel-lean combustion environments with a constant sulfur content. The synthetic deposits contained FeS2, FeS, Fe3O4 and/or carbon. Reaction kinetics was studied in individual gas-metal, gas deposit, and deposit-alloy systems. A test method was developed to investigate simultaneous gas-deposit-metal corrosion reactions. The results showed reaction kinetics varied widely, depending on the gas-alloy system and followed linear, parabolic, and logarithmic rate laws. Under reducing conditions, the alloys exhibited a range of corrosion mechanisms including carburization-sulfidation, sulfidation, and sulfidation-oxidation. Most alloys were not resistant to the highly reducing gases but offered moderate resistance to mixed oxidation-sulfidation by demonstrating parabolic or logarithmic behavior. Under oxidizing conditions, all of the alloys were resistant. Under oxidizing-sulfating conditions, alloys with high Fe or Cr contents sulfated whereas an alloy containing Mo and W was resistant. In the gas-deposit-metal tests, FeS2-bearing deposits were extremely corrosive to low alloy steel under both reducing and oxidizing conditions but they had little influence on the weld claddings. Accelerated corrosion was attributed to rapid decomposition or oxidation of FeS2 particles that generated sulfur-rich gases above the alloy surface. In contrast, FeS-type deposits had no influence under reducing conditions but they were aggressive to low alloy steel under oxidizing conditions. The extent of damage

  4. Surface modification of high temperature iron alloys

    DOEpatents

    Park, Jong-Hee

    1995-01-01

    A method and article of manufacture of a coated iron based alloy. The method includes providing an iron based alloy substrate, depositing a silicon containing layer on the alloy surface while maintaining the alloy at a temperature of about 700.degree. C.-1200.degree. C. to diffuse silicon into the alloy surface and exposing the alloy surface to an ammonia atmosphere to form a silicon/oxygen/nitrogen containing protective layer on the iron based alloy.

  5. Surface modification of high temperature iron alloys

    DOEpatents

    Park, J.H.

    1995-06-06

    A method and article of manufacture of a coated iron based alloy are disclosed. The method includes providing an iron based alloy substrate, depositing a silicon containing layer on the alloy surface while maintaining the alloy at a temperature of about 700--1200 C to diffuse silicon into the alloy surface and exposing the alloy surface to an ammonia atmosphere to form a silicon/oxygen/nitrogen containing protective layer on the iron based alloy. 13 figs.

  6. Materials corrosion of high temperature alloys immersed in 600C binary nitrate salt.

    SciTech Connect

    Kruizenga, Alan Michael; Gill, David Dennis; LaFord, Marianne Elizabeth

    2013-03-01

    Thirteen high temperature alloys were immersion tested in a 60/40 binary nitrate salt. Samples were interval tested up to 3000 hours at 600ÀC with air as the ullage gas. Chemical analysis of the molten salt indicated lower nitrite concentrations present in the salt, as predicted by the equilibrium equation. Corrosion rates were generally low for all alloys. Corrosion products were identified using x-ray diffraction and electron microprobe analysis. Fe-Cr based alloys tended to form mixtures of sodium and iron oxides, while Fe-Ni/Cr alloys had similar corrosion products plus oxides of nickel and chromium. Nickel based alloys primarily formed NiO, with chromium oxides near the oxide/base alloy interface. In625 exhibited similar corrosion performance in relation to previous tests, lending confidence in comparisons between past and present experiments. HA230 exhibited internal oxidation that consisted of a nickel/chromium oxide. Alloys with significant aluminum alloying tended to exhibit superior performance, due formation of a thin alumina layer. Soluble corrosion products of chromium, molybdenum, and tungsten were also formed and are thought to be a significant factor in alloy performance.

  7. Novel production method and in-vitro cell compatibility of porous Ti-6Al-4V alloy disk for hard tissue engineering.

    PubMed

    Bhattarai, Shanta Raj; Khalil, Khalil Abdel-Razek; Dewidar, Montasser; Hwang, Pyoung Han; Yi, Ho Keun; Kim, Hak Yong

    2008-08-01

    Porous metals are attractive due to its unique physical, mechanical, and new bone tissue ingrowth properties. In the present study, the production of highly porous Ti-6Al-4V parts by powder metallurgical technology and subsequently it's uses in in vitro bone tissue engineering is described. A space-holder method using carbamide with different particle size to produce parts with porosities between 35 and 70% were applied. The compressive strength and Young's modulus of porous Ti-6Al-4V were determined. Results indicated that stress and Young's modulus decrease with increasing porosity and pore size. The porous parts are characterized by scanning electron microscopy. Furthermore, study was to investigate the effects of three different porosities of porous Ti-6Al-4V (35, 50, and 70%) on proliferation, differentiation, and cell-matrix interaction of mouse osteoblast-like cells, MC-3T3. Results showed that the cell proliferation was significantly (p < 0.05) higher on 70% porous Ti-6Al-4V. However, synthesis of different types of extra cellular matrix proteins was also more abundant on 70% porous Ti-6Al-4V than 35 and 50% porous Ti-6Al-4V disk except some specific proteins. An increase in alkaline phosphate activity was significantly (p < 0.05) higher on 70 and 50% porous Ti-6Al-4V disk after 12 days of MC-3T3 cells incubation. Above all, results indicated that porosity (nearly 70%) of porous Ti-6Al-4V topography affects proliferation and differentiation of osteoblast-like MC-3T3 cells. The results showed that this novel process is a promise to fabricate porous biomaterials for bone implants.

  8. Microstructure and lateral conductivity control of hydrogenated nanocrystalline silicon oxide and its application in a-Si:H/a-SiGe:H tandem solar cells

    NASA Astrophysics Data System (ADS)

    Tian-Tian, Li; Tie, Yang; Jia, Fang; De-Kun, Zhang; Jian, Sun; Chang-Chun, Wei; Sheng-Zhi, Xu; Guang-Cai, Wang; Cai-Chi, Liu; Ying, Zhao; Xiao-Dan, Zhang

    2016-04-01

    Phosphorous-doped hydrogenated nanocrystalline silicon oxide (n-nc-SiO x :H) films are prepared via radio frequency plasma enhanced chemical vapor deposition (RF-PECVD). Increasing deposition power during n-nc-SiO x :H film growth process can enhance the formation of nanocrystalline and obtain a uniform microstructure of n-nc-SiO x :H film. In addition, in 20s interval before increasing the deposition power, high density small grains are formed in amorphous SiO x matrix with higher crystalline volume fraction (I c) and have a lower lateral conductivity. This uniform microstructure indicates that the higher I c can leads to better vertical conductivity, lower refractive index, wider optical band-gap. It improves the back reflection in a-Si:H/a-SiGe:H tandem solar cells acting as an n-nc-SiO x :H back reflector prepared by the gradient power during deposition. Compared with the sample with SiO x back reflector, with a constant power used in deposition process, the sample with gradient power SiO x back reflector can enhance the total short-circuit current density (J sc) and the initial efficiency of a-Si:H/a-SiGe:H tandem solar cells by 8.3% and 15.5%, respectively. Project supported by the Hi-Tech Research and Development Program of China (Grant No. 2013AA050302), the National Natural Science Foundation of China (Grant No. 61474065), Tianjin Municipal Research Key Program of Application Foundation and Advanced Technology, China (Grant No. 15JCZDJC31300), the Key Project in the Science & Technology Pillar Program of Jiangsu Province, China (Grant No. BE2014147-3), and the Specialized Research Fund for the Ph. D. Program of Higher Education, China (Grant No. 20120031110039).

  9. Study of microstructural and optical properties of a-Si:H thin films

    NASA Astrophysics Data System (ADS)

    Jurečka, Stanislav; Müllerová, Jarmila

    2010-12-01

    Undoped amorphous silicon thin films pasivated by hydrogen (a-Si:H) are important for a number of industrial and research applications, especially for optoelectronics, photovoltaics, optical communications, senzorics, laser technology and so on. We experimentally studied properties of the a-Si:H thin films prepared by the plasma-enhanced chemical vapour deposition (PECVD) method. Sample microstructure properties and the effect of the microstructure on optical properties of the a-Si:H thin films deposited by PECVD on glass were analysed. The spectral refractive index, extinction coefficient, and surface morphology were analysed for the series of a-Si:H samples prepared in different technological conditions from H diluted silane plasma. Surface morphology of studied samples was described by the atomic force microscopy (AFM) method. Optical properties of a-Si:H thin films were analysed by numerical optimization of the microstructural and dispersion model of optical parameters relative to the experimental spectral reflectance. The results show that at dilution between 20 and 30 the transition between amorphous and polycrystalline phase occurs. The sample becomes a mixture of amorphous and polycrystalline phase with nano-sized grains and voids with decreasing hydrogen concentration.

  10. Effect of metal/P-doped a-Si:H junctions on the photovoltage of a-Si:H solar cells

    SciTech Connect

    Sakai, Y.; Matsumura, M.; Nakato, Y.; Tsubomura, H.

    1987-10-15

    The open-circuit photovoltages (V/sub oc/) of a-Si:H solar cells having a Glass/TCO/p-i-n a-Si:H/metal structure were examined as a function of the thickness of the n layer. The V/sub oc/ stayed constant at --0.8 V, irrespective of the kind of metals, as far as the thickness of the n layer was larger than 15 nm, but dropped when the n layer got thinner. This effect was the stronger, the smaller the work function of the metal. The decrease of V/sub oc/ is attributed to complete depletion of the n layer, leading to the reduction of the potential gradient in the i layer. The effects of the metal/P-doped a-Si:H junction were further investigated using cells having a Glass/TCO/n-i-n/metal structure and different doping concentrations for the latter n layer. The results obtained supported the above-mentioned conclusion.

  11. Processing of Refractory Metal Alloys for JOYO Irradiations

    SciTech Connect

    RF Luther; ME Petrichek

    2006-02-21

    This is a summary of the refractory metal processing experienced by candidate Prometheus materiats as they were fabricated into specimens destined for testing within the JOYO test reactor, ex-reactor testing at Oak Ridge National Laboratory (ORNL), or testing within the NRPCT. The processing is described for each alloy from the point of inception to the point where processing was terminated due to the cancellation of Naval Reactor's involvement in the Prometheus Project. The alloys included three tantalum-base alloys (T-111, Ta-10W, and ASTAR-811C), a niobium-base alloy, (FS-85), and two molybdenum-rhenium alloys, one containing 44.5 w/o rhenium, and the other 47.5 w/o rhenium. Each of these alloys was either a primary candidate or back-up candidate for cladding and structural applications within the space reactor. Their production was intended to serve as a forerunner for large scale production ingots that were to be procured from commercial refractory metal vendors such as Wah Chang.

  12. Nitrate reduction in water by aluminum alloys particles.

    PubMed

    Bao, Zunsheng; Hu, Qing; Qi, Weikang; Tang, Yang; Wang, Wei; Wan, Pingyu; Chao, Jingbo; Yang, Xiao Jin

    2017-07-01

    Nano zero-valent iron (NZVI) particles have been extensively investigated for nitrate reduction in water. However, the reduction by NZVI requires acidic pH conditions and the final product is exclusively ammonium, leading to secondary contamination. In addition, nanomaterials have potential threats to environment and the transport and storage of nanomaterials are of safety concerns. Aluminum, the most abundant metal element in the earth's crust, is able to reduce nitrate, but the passivation of aluminum limits its application. Here we report Al alloys (85% Al) with Fe, Cu or Si for aqueous nitrate reduction. The Al alloys particles of 0.85-0.08 mm were inactivate under ambient conditions and a simple treatment with warm water (45 °C) quickly activated the alloy particles for rapid reduction of nitrate. The Al-Fe alloy particles at a dosage of 5 g/L rapidly reduced 50 mg-N/L nitrate at a reaction rate constant (k) of 3.2 ± 0.1 (mg-N/L)(1.5)/min between pH 5-6 and at 4.0 ± 0.1 (mg-N/L)(1.5)/min between pH 9-11. Dopping Cu in the Al-Fe alloy enhanced the rates of reduction whereas dopping Si reduced the reactivity of the Al-Fe alloy. The Al alloys converted nitrate to 20% nitrogen and 80% ammonium. Al in the alloy particles provided electrons for the reduction and the intermetallic compounds in the alloys were likely to catalyze nitrate reduction to nitrogen. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. NDE detectability of fatigue type cracks in high strength alloys

    NASA Technical Reports Server (NTRS)

    Christner, B. K.; Rummel, W. D.

    1983-01-01

    Specimens suitable for investigating the reliability of production nondestructive evaluation (NDE) to detect tightly closed fatigue cracks in high strength alloys representative of those materials used in spacecraft engine/booster construction were produced. Inconel 718 was selected as representative of nickel base alloys and Haynes 188 was selected as representative of cobalt base alloys used in this application. Cleaning procedures were developed to insure the reusability of the test specimens and a flaw detection reliability assessment of the fluorescent penetrant inspection method was performed using the test specimens produced to characterize their use for future reliability assessments and to provide additional NDE flaw detection reliability data for high strength alloys. The statistical analysis of the fluorescent penetrant inspection data was performed to determine the detection reliabilities for each inspection at a 90% probability/95% confidence level.

  14. On the Modeling of Plastic Deformation of Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Ertürk, S.; Steglich, D.; Bohlen, J.; Letzig, D.; Brocks, W.

    2007-05-01

    Magnesium alloys are promising materials due to their low density and therefore high specific strength. However, the industrial application is not well established so far, especially for wrought products such as sheets or profiles. Due to its hexagonal crystallographic structure, deformation mechanisms observed in magnesium alloys are rather different from those in face centered cubic metals such as aluminum alloys. This leads not only to a mechanical anisotropy, but also to a tension-compression asymmetry, i.e. unequal compressive and tensile yield strength. The resulting complexity in the yielding behavior of such materials cannot be captured by conventional models of J2 plasticity. Cazacu and Barlat, therefore, proposed a phenomenological yield potential which accounts for the respective phenomena by introducing the third invariant of the stress tensor. Simulations based on this model are performed with ABAQUS/Explicit and a user defined routine VUMAT for validating the respective implementation. The application aims at simulating the extrusion process of magnesium alloys.

  15. Electrochemical method of producing eutectic uranium alloy and apparatus

    DOEpatents

    Horton, James A.; Hayden, H. Wayne

    1995-01-01

    An apparatus and method for continuous production of liquid uranium alloys through the electrolytic reduction of uranium chlorides. The apparatus includes an electrochemical cell formed from an anode shaped to form an electrolyte reservoir, a cathode comprising a metal, such as iron, capable of forming a eutectic uranium alloy having a melting point less than the melting point of pure uranium, and molten electrolyte in the reservoir comprising a chlorine or fluorine containing salt and uranium chloride. The method of the invention produces an eutectic uranium alloy by creating an electrolyte reservoir defined by a container comprising an anode, placing an electrolyte in the reservoir, the electrolyte comprising a chlorine or fluorine containing salt and uranium chloride in molten form, positioning a cathode in the reservoir where the cathode comprises a metal capable of forming an uranium alloy having a melting point less than the melting point of pure uranium, and applying a current between the cathode and the anode.

  16. Chemistry related to the procurement of vanadium alloys

    SciTech Connect

    Smith, H.M.; Chung H.M.; Tsai, H.C.

    1997-08-01

    Evaluation of trace element concentrations in vanadium alloys is important to characterize the low-activation characteristics and possible effects of trace elements on the properties. Detailed chemical analysis of several vanadium and vanadium alloy heats procured for the Argonne vanadium alloy development program were analyzed by Johnson-Matthey (UK) as part of a joint activity to evaluate trace element effects on the performance characteristics. These heats were produced by normal production practices for high grade vanadium. The analyses include approximately 60 elements analyzed in most cases by glow-discharge mass spectrometry. Values for molybdenum and niobium, which are critical for low-activation alloys, ranged from 0.4 to 60 wppm for the nine heats.

  17. On the Modeling of Plastic Deformation of Magnesium Alloys

    SciTech Connect

    Ertuerk, S.; Steglich, D.; Bohlen, J.; Letzig, D.; Brocks, W.

    2007-05-17

    Magnesium alloys are promising materials due to their low density and therefore high specific strength. However, the industrial application is not well established so far, especially for wrought products such as sheets or profiles. Due to its hexagonal crystallographic structure, deformation mechanisms observed in magnesium alloys are rather different from those in face centered cubic metals such as aluminum alloys. This leads not only to a mechanical anisotropy, but also to a tension-compression asymmetry, i.e. unequal compressive and tensile yield strength. The resulting complexity in the yielding behavior of such materials cannot be captured by conventional models of J2 plasticity. Cazacu and Barlat, therefore, proposed a phenomenological yield potential which accounts for the respective phenomena by introducing the third invariant of the stress tensor. Simulations based on this model are performed with ABAQUS/Explicit and a user defined routine VUMAT for validating the respective implementation. The application aims at simulating the extrusion process of magnesium alloys.

  18. Alloyed coatings for dispersion strengthened alloys

    NASA Technical Reports Server (NTRS)

    Wermuth, F. R.; Stetson, A. R.

    1971-01-01

    Processing techniques were developed for applying several diffusion barriers to TD-Ni and TD-NiCr. Barrier coated specimens of both substrates were clad with Ni-Cr-Al and Fe-Cr-Al alloys and diffusion annealed in argon. Measurement of the aluminum distribution after annealing showed that, of the readily applicable diffusion barriers, a slurry applied tungsten barrier most effectively inhibited the diffusion of aluminum from the Ni-Cr-Al clad into the TD-alloy substrates. No barrier effectively limited interdiffusion of the Fe-Cr-Al clad with the substrates. A duplex process was then developed for applying Ni-Cr-Al coating compositions to the tungsten barrier coated substrates. A Ni-(16 to 32)Cr-3Si modifier was applied by slurry spraying and firing in vacuum, and was then aluminized by a fusion slurry process. Cyclic oxidation tests at 2300 F resulted in early coating failure due to inadequate edge coverage and areas of coating porosity. EMP analysis showed that oxidation had consumed 70 to 80 percent of the aluminum in the coating in less than 50 hours.

  19. Weldable ductile molybdenum alloy development

    NASA Astrophysics Data System (ADS)

    Cockeram, B. V.; Ohriner, E. K.; Byun, T. S.; Miller, M. K.; Snead, L. L.

    2008-12-01

    Molybdenum and its alloys are attractive structural materials for high-temperature applications. However, various practical issues have limited its use. One concern relates to the loss of ductility occurring in the heat-affected weld zone caused by segregation of oxygen to grain boundaries. In this study, a series of arc melted molybdenum alloys have been produced containing controlled additions of B, C, Zr, and Al. These alloys were characterized with respect to their tensile properties, smooth bend properties, and impact energy for both the base metal and welds. These alloys were compared with a very high purity low carbon arc cast molybdenum reference. For discussion purposes the alloys produced are separated into two categories: Mo-Al-B alloys, and Mo-Zr-B alloys. The properties of Mo-Zr-B alloy welds containing higher carbon levels exhibited slight improvement over unalloyed molybdenum, though the base-metal properties for all Mo-Zr-B alloys were somewhat inconsistent with properties better, or worse, than unalloyed molybdenum. A Mo-Al-B alloy exhibited the best DBTT values for welds, and the base metal properties were comparable to or slightly better than unalloyed molybdenum. The Mo-Al-B alloy contained a low volume fraction of second-phase particles, with segregation of boron and carbon to grain boundaries believed to displace oxygen resulting in improved weld properties. The volume fractions of second-phase particles are higher for the Mo-Zr-B alloys, and these alloys were prone to brittle fracture. It is also noted that these Mo-Zr-B alloys exhibited segregation of zirconium, boron and carbon to the grain boundaries.

  20. Half-Corbino short-channel amorphous In-Ga-Zn-O thin-film transistors with a-SiOx or a-SiOx/a-SiNx passivation layers

    NASA Astrophysics Data System (ADS)

    Zhao, Chumin; Fung, Tze-Ching; Kanicki, Jerzy

    2016-06-01

    We investigated the electrical properties and stability of short-channel half-Corbino amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs). In the linear region, the fabricated half-Corbino a-IGZO TFT with a channel length of 4.5 μm achieves a geometrical factor (fg) of ∼2.7, a threshold voltage (VT) of ∼2.4 V, a field-effect mobility (μeff) of ∼15 cm2/Vs, a subthreshold swing (SS) of ∼320 mV/dec and an off-current (IOFF) < 10-13 A. In the saturation region, asymmetric electrical characteristics such as drain current were observed under different drain bias conditions. The electrical properties asymmetry of half-Corbino a-IGZO TFTs was explained by various geometrical factors owing to the short-channel effect. The reduced VT and increased SS at VDS = 15 V is explained by the drain-induced Schottky barrier lowering. In addition, the bias-temperature stress (BTS) was performed for half-Corbino a-IGZO TFTs with both amorphous silicon oxide (a-SiOx) single layer and a-SiOx/amorphous silicon nitride (a-SiNx) bilayer passivation (PV) structures. The device with bilayer PV shows a threshold voltage shift (ΔVT) of +2.07 and -0.5 V under positive (PBTS = +15 V) and negative BTS (NBTS = -15 V) at 70 °C for 10 ks, respectively. The origins of ΔVT during PBTS and NBTS for half-Corbino a-IGZO TFTs with single and bilayer PV structures were studied. To improve the device electrical stability, the bilayer PV structure should be used.

  1. Eutectic-Alloy Morphology

    NASA Technical Reports Server (NTRS)

    Pirich, R. G.; Poit, W. J.

    1985-01-01

    Deviation in controlled-rod eutectic morphology anticipated for diffusion only crystal growth characterized at low solidification velocities. Naturally induced, gravity-related convective instabilities result in nonalined irregularly dispersed fibers or platelets. Lower solidification limit for controlled growth Bi/Mn alloys is 1 centimeter/ hour.

  2. Superplasticity in aluminum alloys

    SciTech Connect

    Nieh, T. G.

    1997-12-01

    We have characterized in the Al-Mg system the microstructure and mechanical properties of a cold-rolled Al-6Mg-0.3Sc alloy. The alloy exhibited superplasticity at relatively high strain rates (about 10-2 s-1). At a strain rate of 10-2 s-1 there exists a wide temperature range (475-520`C) within which the tensile elongation is over 1000%. There also exists a wide strain rate range (10-3 - 10-1 s-1) within which the tensile elongation is over 500%. The presence of Sc in the alloy results in a uniform distribution of fine coherent Al3SC precipitates which effectively pin grain and subgrain boundaries during static and continuous recrystallization. As a result, the alloy retains its fine grain size (about 7 micron), even after extensive superplastic deformation (>1000%). During deformation, dislocations Mg with a high Schmidt factor slip across subgrains but are trapped by subgrain boundaries, as a result of the strong pining of Al3Sc. This process leads to the conversion of low-angled subgrain boundaries to high-angled grain boundaries and the subsequent grain boundary sliding, which produces superelasticity. A model is proposed to describe grain boundary sliding accommodated by dislocation glide across grains with a uniform distribution of coherent precipitates. The model predictions is consistent with experimental observations.

  3. Shape Memory Alloy Actuator

    NASA Technical Reports Server (NTRS)

    Baumbick, Robert J. (Inventor)

    2000-01-01

    The present invention discloses and teaches a unique, remote optically controlled micro actuator particularly suitable for aerospace vehicle applications wherein hot gas, or in the alternative optical energy, is employed as the medium by which shape memory alloy elements are activated. In gas turbine powered aircraft the source of the hot gas may be the turbine engine compressor or turbine sections.

  4. Shape Memory Alloy Actuator

    NASA Technical Reports Server (NTRS)

    Baumbick, Robert J. (Inventor)

    2002-01-01

    The present invention discloses and teaches a unique, remote optically controlled micro actuator particularly suitable for aerospace vehicle applications wherein hot gas, or in the alternative optical energy, is employed as the medium by which shape memory alloy elements are activated. In gas turbine powered aircraft the source of the hot gas may be the turbine engine compressor or turbine sections.

  5. Quinary metallic glass alloys

    DOEpatents

    Lin, X.; Johnson, W.L.

    1998-04-07

    At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10{sup 3}K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf){sub a}(Al,Zn){sub b}(Ti,Nb){sub c}(Cu{sub x}Fe{sub y}(Ni,Co){sub z}){sub d} wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d{hor_ellipsis}y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

  6. Microporosity in casting alloys.

    PubMed

    Lewis, A J

    1975-06-01

    Three series of tensile test pieces were produced using a nickel base partial denture casting alloy. For the first series induction heating was employed, for the second a resistance crucible, and for the third an oxy-acetylene torch. Samples from each series were sectioned longitudinally, mounted, polished and examined microscopically for evidence of microporosity.

  7. Quinary metallic glass alloys

    DOEpatents

    Lin, Xianghong; Johnson, William L.

    1998-01-01

    At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10.sup.3 K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf).sub.a (Al,Zn).sub.b (Ti,Nb).sub.c (Cu.sub.x Fe.sub.y (Ni,Co).sub.z).sub.d wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d.multidot.y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

  8. Silver alloy compositions

    SciTech Connect

    Berhard, M.; Sivertsen, J.T.

    1990-11-27

    This patent describes a silver alloy composition. It comprises essentially all of the following parts by weight: about 89-93.5% silver, about 0.01-2% silicon, about 0.001-2% boron, about 0.5-5% zinc, about 0.5-6% copper, about 0.25-2% tin, and about 0.01-1.25% indium.

  9. Growth temperature effect on a-Si:H thin films studied by constant photocurrent method

    NASA Astrophysics Data System (ADS)

    Wadibhasme, N. A.; Dusane, R. O.

    2013-02-01

    Hydrogenated amorphous silicon (a-Si:H) thin films are synthesized by tuning different process parameters among which substrate temperature of film growth plays an important role in monitoring the device quality of the film. In this paper we have used the constant photocurrent method (CPM) to study the effect of growth temperature on the electronic and optical parameters of a-Si:H films at different photon energies. This technique primarily measures the absorption coefficient which is a result of different electronic transitions that contribute to the photocurrent. The nature of absorption coefficient changes with growth temperature that explicitly provides the information about the density of defect states present in the mid gap of a-Si:H.

  10. Si6H12/Polymer Inks for Electrospinning a-Si Nanowire Lithium Ion Battery Anodes

    SciTech Connect

    Schulz, Douglas L.; Hoey, Justin; Smith, Jeremiah; Elangovan, Arumugasamy; Wu, Xiangfa; Akhatov, Iskander; Payne, Scott; Moore, Jayma; Boudjouk, Philip; Pederson, Larry; Xiao, Jie; Zhang, Jiguang

    2010-08-04

    Amorphous silicon nanowires 'a-SiNWs' have been prepared by electrospinning a liquid silane-based precursor. Cyclohexasilane 'Si6H12' was admixed with poly-methyl methacrylate (PMMA) in toluene giving an ink that was electrospun into the Si6H12/PPMA wires with diameters of 50-2000 nm. Raman spectroscopy revealed that thermal treatment at 350 C transforms this deposit into a-SiNWs. These materials were coated with a thin carbon layer and then tested as half-cells where a reasonable plateau in electrochemical cycling was observed after an initial capacity fade. Additionally, porous a-SiNWs were realized when the thermally decomposable binder polypropylene carbonate/polycyclohexene carbonate was used as the polymer carrier.

  11. Photo and electroluminescence from PECVD grown a-Si:H/SiO 2 multilayers

    NASA Astrophysics Data System (ADS)

    Ovchinnikov, V.; Malinin, A.; Sokolov, V.; Kilpelä, O.; Sinkkonen, J.

    2001-06-01

    Multilayers (ML) of a-Si:H/SiO 2 have been grown using plasma enhanced chemical vapor deposition. Room-temperature photoluminescence (PL) and electroluminescence (EL) in the range 1.35-1.8 eV has been observed in as-deposited and annealed samples. A noticeable redshift of the PL peak has been detected by increasing the a-Si:H layer thickness in the range 0.7-2.1 nm, as well as the annealing temperature (700-1200°C). The strong correlation between PL and EL spectra indicates that light emission from a-Si:H/SiO 2 ML can be attributed to the same luminescence centers in Si layers and nanoclusters. The luminescence mechanism can be interpreted in terms of quantum and spatial confinement of carriers.

  12. Ab initio calculation of vibrational properties of a-Si:H with inner voids

    NASA Astrophysics Data System (ADS)

    Nakhmanson, S. M.; Drabold, D. A.

    1998-05-01

    We have performed an ab initio calculation of vibrational properties of hydrogenated amorphous silicon (a-Si:H) using a molecular dynamics method. A Wooten, Winer, Weaire (WWW) 216 atom model for pure amorphous silicon (a-Si) updated by Djordjevic, Thorpe and Wooten has been employed as a ``base'' for our a-Si:H models with voids that were made by removing a cluster of silicon atoms out of the bulk and terminating the resulting dangling bonds with hydrogens. Our calculation shows that the presence of voids leads to localized low energy (30-50 cm-1) states in vibrational spectrum of the system. The nature and localization properies of these states are carefully analysed by various visualization techniques. Web resources: http://www.phy.ohiou.edu/ ĩnakhmans/Professional/Bubbles/bubpr.htm

  13. Optical absorptions in ZnO/a-Si distributed Bragg reflectors

    NASA Astrophysics Data System (ADS)

    Chen, Aqing; Chen, Zhian; Zhu, Kaigui; Ji, Zhenguo

    2017-01-01

    The distributed Bragg reflectors (DBRs) consisting of alternating layers of ZnO and heavy doped amorphous silicon (a-Si) have been fabricated by magnetron sputtering. It is novel to find that the optical absorptions exist in the stopband of the DBRs, and that many discrete strong optical absorption peaks exist in the wavelength range of visible to near-infrared. The calculated results by FDTD show that the absorptions in the stopband mainly exist in the first a-Si layer, and that the light absorbed by other a-Si layers inside contributes to the two absorption peaks in near-infrared range. The strong absorptions ranged from visible to infrared open new possibilities to the enhancement of the performance of amorphous silicon solar cells.

  14. Materials Properties Database for Selection of High-Temperature Alloys and Concepts of Alloy Design for SOFC Applications

    SciTech Connect

    Yang, Z Gary; Paxton, Dean M.; Weil, K. Scott; Stevenson, Jeffry W.; Singh, Prabhakar

    2002-11-24

    To serve as an interconnect / gas separator in an SOFC stack, an alloy should demonstrate the ability to provide (i) bulk and surface stability against oxidation and corrosion during prolonged exposure to the fuel cell environment, (ii) thermal expansion compatibility with the other stack components, (iii) chemical compatibility with adjacent stack components, (iv) high electrical conductivity of the surface reaction products, (v) mechanical reliability and durability at cell exposure conditions, (vii) good manufacturability, processability and fabricability, and (viii) cost effectiveness. As the first step of this approach, a composition and property database was compiled for high temperature alloys in order to assist in determining which alloys offer the most promise for SOFC interconnect applications in terms of oxidation and corrosion resistance. The high temperature alloys of interest included Ni-, Fe-, Co-base superal

  15. Flexible micromorph tandem a-Si/{mu}c-Si solar cells

    SciTech Connect

    Soederstroem, T.; Haug, F.-J.; Terrazzoni-Daudrix, V.; Ballif, C.

    2010-01-15

    The deposition of a stack of amorphous (a-Si:H) and microcrystalline ({mu}c-Si:H) tandem thin film silicon solar cells (micromorph) requires at least twice the time used for a single junction a-Si:H cell. However, micromorph devices have a higher potential efficiency, thanks to the broader absorption spectrum of {mu}c-Si:H material. High efficiencies can only be achieved by mitigating the nanocracks in the {mu}c-Si:H cell and the light-induced degradation of the a-Si:H cell. As a result, {mu}c-Si:H cell has to grow on a smooth substrate with large periodicity (>1 {mu}m) and the a-Si:H cell on sharp pyramids with smaller feature size ({approx}350 nm) to strongly scatter the light in the weak absorption spectra of a-Si:H material. The asymmetric intermediate reflector introduced in this work uncouples the growth and light scattering issues of the tandem micromorph solar cells. The stabilized efficiency of the tandem n-i-p/n-i-p micromorph is increased by a relative 15% compared to a cell without AIR and 32% in relative compared to an a-Si:H single junction solar cells. The overall process (T<200 deg. C) is kept compatible with low cost plastic substrates. The best stabilized efficiency of a cell deposited on polyethylene-naphthalate plastic substrate is 9.8% after 1000 h of light soaking at V{sub oc}, 1 sun, and 50 deg. C.

  16. Role of Alloying Additions in Glass Formation and Properties of Bulk Metallic Glasses

    PubMed Central

    Chen, Na; Martin, Laura; Luzguine-Luzgin, Dmitri V.; Inoue, Akihisa

    2010-01-01

    Alloying addition, as a means of improving mechanical properties and saving on costs of materials, has been applied to a broad range of uses and products in the metallurgical fields. In the field of bulk metallic glasses (BMGs), alloying additions have also proven to play effective and important roles in promoting glass formation, enhancing thermal stability and improving plasticity of the materials. Here, we review the work on the role of alloying additions in glass formation and performance improvement of BMGs, with focus on our recent results of alloying additions in Pd-based BMGs. PMID:28883386

  17. Aerospace Patented High-Strength Aluminum Alloy Used in Commercial Industries

    NASA Technical Reports Server (NTRS)

    2004-01-01

    NASA structural materials engineer, Jonathan Lee, displays blocks and pistons as examples of some of the uses for NASA's patented high-strength aluminum alloy originally developed at Marshall Space Flight Center in Huntsville, Alabama. NASA desired an alloy for aerospace applications with higher strength and wear-resistance at elevated temperatures. The alloy is a solution to reduce costs of aluminum engine pistons and lower engine emissions for the automobile industry. The Boats and Outboard Engines Division at Bombardier Recreational Products of Sturtevant, Wisconsin is using the alloy for pistons in its Evinrude E-Tec outboard engine line.

  18. Promising CuNi&.sbnd;CrSi alloy for first wall ITER applications

    NASA Astrophysics Data System (ADS)

    Ivanov, A.; Abramov, V.; Rodin, M.

    1996-10-01

    Precipitation-hardened CuNiCrSi alloy, a promising material for ITER applications, is considered. Available commercial products, chemical composition, physical and mechanical properties are presented. Embrittlement of CuNiCrSi alloy at 250-300°C is observed. Mechanical properties of CuNiCrSi alloy neutron irradiated to a dose of ˜0.2 dpa at 293°C are investigated. Embrittlement of CuNiCrSi alloy can be avoided by annealing.

  19. Formation of titanium carbide layer by laser alloying with a light-transmitting resin

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Takuto; Hagino, Hideki

    2017-01-01

    The weight reduction of mechanical components is becoming increasingly important, especially in the transportation industry, as fuel efficiency continues to improve. Titanium and titanium alloys are recognized for their outstanding potential as lightweight materials with high specific strength. Yet they also have poor tribological properties that preclude their use for sliding parts. Improved tribological properties of titanium would expand the application of titanium into different fields. Laser alloying is an effective process for improving surface properties such as wear resistance. The process has numerous advantages over conventional surface modification techniques. Many researchers have reported the usefulness of laser alloying as a technique to improve the wear resistance of titanium. The process has an important flaw, however, as defects such as cracks or voids tend to appear in the laser-alloyed zone. Our group performed a novel laser-alloying process using a light-transmitting resin as a source for the carbon element. We laser alloyed a surface layer of pure titanium pre-coated with polymethyl methacrylate (PMMA) and investigated the microstructure and wear properties. A laser-alloyed zone was formed by a reaction between the molten titanium and thermal decomposition products of PMMA at the interface between the substrate and PMMA. The cracks could be eliminated from the laser-alloyed zone by optimizing the laser alloying conditions. The surface of the laser-alloyed zone was covered with a titanium carbide layer and exhibited a superior sliding property and wear resistance against WC-Co.

  20. Thin-film amorphous silicon alloy research partnership, Phase I. Annual technical progress report, February 2, 1995--February 1, 1996

    SciTech Connect

    Guha, S.

    1996-04-01

    The principal objective of this R&D program is to expand, enhance and accelerate knowledge and capabilities for the development of high-performance, two-terminal multifunction amorphous silicon (a-Si) alloy modules. The near-term goal of the program is to achieve 12% stable module efficiency by 1998 using the multifunction approach. This report describes research on back reflectors of Ag/TiO{sub 2}/ZnO.