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An in situ transmission electron microscopy study of the thermalstability of near-surface microstructures induced by deep rolling andlaser-shock peening

Description: Mechanical surface treatments are known to be effective at improving the fatigue resistance of metallic alloys at elevated temperatures ({approx}550-600 C), even though the near-surface compressive residual stress fields have been annealed out. We have investigated the thermal stability of near-surface microstructures induced by deep rolling and laser-shock peening in an austentic stainless steel (AISI 304) and a titanium alloy (Ti-6Al-4V) using in situ hot-stage transmission electron microscopy. It is found that the improvements in fatigue resistance at elevated temperature are related to the high-temperature stability of the work-hardened near-surface microstructure in each case.
Date: February 24, 2003
Creator: Altenberger, I.; Stach, E.A.; Liu, G.Y.; Nalla, R.K. & Ritchie, R.O.
Partner: UNT Libraries Government Documents Department

Test of a NbTi Superconducting Quadrupole Magnet Based on Alternating Helical Windings

Description: It has been shown that by superposing two solenoid-like thin windings, that are oppositely skewed (tilted) with respect to the bore axis, the combined current density on the surface is cos({theta})-like and the resulting magnetic field in the bore is a pure dipole field. Following a previous test of such a superconducting dipole magnet, a quadrupole magnet was designed and built using similar principles. This paper describes the design, construction and test of a 75 mm bore 600 mm long superconducting quadrupole made with NbTi wire. The simplicity of the design, void of typical wedges, end-spacers and coil assembly, is especially suitable for future high field insert coils using Nb{sub 3}Sn as well as HTS wires. The 3 mm thick coil reached 46 T/m but did not achieve its current plateau.
Date: August 16, 2009
Creator: Caspi, S.; Trillaud, F.; Godeke, A.; Dietderich, D.; Ferracin, P.; Sabbi, G. et al.
Partner: UNT Libraries Government Documents Department

Recent Test Results of the High Field Nb3Sn Dipole Magnet HD2

Description: The 1 m long Nb{sub 3}Sn dipole magnet HD2, fabricated and tested at Lawrence Berkeley National Laboratory, represents a step towards the development of block-type accelerator quality magnets operating in the range of 13-15 T. The magnet design features two coil modules composed of two layers wound around a titanium-alloy pole. The layer 1 pole includes a round cutout to provide room for a bore tube with a clear aperture of 36 mm. After a first series of tests where HD2 reached a maximum bore field of 13.8 T, corresponding to an estimated peak field on the conductor of 14.5 T, the magnet was disassembled and reloaded without the bore tube and with a clear aperture increased to 43 mm. We describe in this paper the magnet training observed in two consecutive tests after the removal of the bore tube, with a comparison of the quench performance with respect to the previous tests. An analysis of the voltage signals recorded before and after training quenches is then presented and discussed, and the results of coil visual inspections reported.
Date: October 19, 2009
Creator: Ferracin, P.; Bingham, B.; Caspi, S.; Cheng, D. W.; Dietderich, D. R.; Felice, H. et al.
Partner: UNT Libraries Government Documents Department

Comparative Corrosion Behavior of Two Palladium Containing Titanium Alloys

Description: The ASTM standard B 265 provides the requirements for the chemical composition of titanium (Ti) alloys. It is planned to use corrosion resistant and high strength titanium alloys to fabricate the drip shield at the proposed Yucca Mountain Repository. Titanium grade (Gr) 7 (R52400) and other Ti alloys are currently being characterized for this application. Ti Gr 7 contains 0.15% Palladium (Pd) to increase its corrosion performance. In this article we report results on the comparative short term corrosion behavior of Ti Gr 7 and a Ruthenium (Ru) containing alloy (Ti Gr 33). Ti Gr 33 also contains a small amount of Pd. Limited electrochemical testing such as polarization resistance and cyclic potentiodynamic curves showed that both alloys have a similar corrosion behavior in the tested environments.
Date: February 5, 2006
Creator: Lian, T; Yashiki, T; Nakayama, T; Nakanishi, T & Rebak, R B
Partner: UNT Libraries Government Documents Department

COMPARATIVE CORROSION BEHAVIOR OF TWO PALLADIUM CONTAINING TITANIUM ALLOYS

Description: The ASTM standard B 265 provides the requirements for the chemical composition of titanium (Ti) alloys. It is planned to use corrosion resistant and high strength titanium alloys to fabricate the drip shield at the proposed Yucca Mountain Repository. Titanium grade (Gr) 7 (R52400) and other Ti alloys are currently being characterized for this application. Ti Gr 7 contains 0.15% Palladium (Pd) to increase its corrosion performance. In this article we report results on the comparative short term corrosion behavior of Ti Gr 7 and a Ruthenium (Ru) containing alloy (Ti Gr 33). Ti Gr 33 also contains a small amount of Pd. Limited electrochemical testing such as polarization resistance and cyclic potentiodynamic curves showed that both alloys have a similar corrosion behavior in the tested environments.
Date: July 23, 2006
Creator: T. Lian, T. Yashiki, T. Nakayama, T. Nakanishi, R. B. Rebak
Partner: UNT Libraries Government Documents Department

Anodic Polarization Behavior of Titanium Grade 7 in Dust Deliquescence Salt Environments

Description: It is planned to use the highly corrosion resistant titanium grade 7 (Ti Gr 7) and a high strength titanium alloy (Ti Gr 29) to fabricate the drip shield for the Yucca Mountain repository. Ti Gr 7 contains 0.15% Palladium (Pd) to increase its corrosion performance, mainly under reducing conditions. It was important to determine the corrosion behavior of Ti Gr 7 in concentrated brines at temperatures higher than 100 C, which may represent the behavior of dust deliquescence solutions. Tests were performed in concentrated NaCl + KCl solutions containing also nitrates and fluorides. Results show that Ti Gr 7 was highly resistant to general and localized corrosion. Some specimens were polarized to potentials higher than 4 volts. None of the tightly creviced specimens suffered crevice corrosion. The presence of fluoride promoted localized corrosion around the edges of the crevice former.
Date: March 9, 2007
Creator: Evans, K J & Rebak, R B
Partner: UNT Libraries Government Documents Department

Influence of shockwave profile on ejection of micron-scale material from shocked Sn surfaces: an experimental study

Description: This effort experimentally investigates the relationship between shock-breakout pressure and the amount of micron-scale fragments ejected (ejecta) upon shock release at the metal/vacuum interface of Sn targets shocked with a supported shockwave. The results are compared with an analogous set derived from HE shocked Sn targets, Taylor shockwave loading. The supported shock-pulse was created by impacting a Sn target with a Ti64 (Ti-6Al-4V) impactor that was accelerated using a powder gun. Ejecta production at the free-surface or back-side of the Sn targets were characterized through use of piezoelectric pins and Asay foils, and heterodyne velocimetry verified the time of shock release and the breakout pressure.
Date: January 1, 2009
Creator: Zellner, Michael B; Byers, Mark E; Hammerberg, James E; Germann, Tim C; Dimonte, Guy; Rigg, Paulo A et al.
Partner: UNT Libraries Government Documents Department

Use of Friction Stir Welding and Friction Stir Processing for Advanced Nuclear Fuels and Materials Joining Applications

Description: Application of the latest developments in materials technology may greatly aid in the successful pursuit of next generation reactor and transmutation technologies. One such area where significant progress is needed is joining of advanced fuels and materials. Rotary friction welding, also referred to as friction stir welding (FSW), has shown great promise as a method for joining traditionally difficult to join materials such as aluminum alloys. This relatively new technology, first developed in 1991, has more recently been applied to higher melting temperature alloys such as steels, nickel-based and titanium alloys. An overview of the FSW technology is provided and two specific nuclear fuels and materials applications where the technique may be used to overcome limitations of conventional joining technologies are highlighted.
Date: June 1, 2006
Creator: Cole, J. I. & Jue, J. F.
Partner: UNT Libraries Government Documents Department

Shape memory alloy seals for geothermal applications

Description: Rockwell International's Energy Systems Group, under contract to Brookhaven National Laboratory, has completed a 2-year program to develop a novel temperature-actuated seal concept for geothermal applications. This seal concept uses the unique properties of a shape memory alloy (Nitinol) to perform the sealing function. The several advantages of the concept are discussed in the paper. Demonstration tests of both face and shaft seals have shown that leaktight seals are feasible. Supporting materials studies have included corrosion tests in geothermal fluids, elevated temperature tensile tests, experimental electroplating and metallographic evaluations of microstructures.
Date: October 8, 1982
Creator: Friske, Warren H. & Schwartzbart, Harry
Partner: UNT Libraries Government Documents Department

Effect of helium on high-temperature tensile properties and swelling of vanadium and vanadium alloys

Description: From fifth symposium on engineering problems of fusion research; Princeton, New Jersey, USA (6 Nov 1973). Sheet tensile samples of V-15 wt% Cr-5 wt% Ti were implanted with ~25 atomic ppM of helium at the ANL Cyclotron and tested at temperatures from 650 to 900 deg C. When compared with the control samples, the helium-injected samples show an increasing loss of ductility with increasing temperatures above 700 deg C. The loss of ductility in the helium- injected samples is accompanied by transition from a ductile, transgranular fracture to a completely intergranular fracture. The control samples fracture transgranularly throughout the range of test temperature. The effect of helium on void swelling was studied in two grades of vanadium using heavy-ion bombardment. High-purity vanadium (145 ppM C + N + O) and commercial-purity vanadium (1220 ppm C + N + O) were bombarded with 3.25-MeV Ni/sup +/ ions at 650 and 750 deg C to a damage level of 60 displacements per atom after preinjection with helium. Quantitative microscopy of the irradiated samples showed that the overall swelling was unaffected at 650 deg C, but was significantly reduced at 750 deg C, if the helium content was increased from 10 to 100 atomic ppM. The reduction in swelling appears to be associated with the presence of a high concentration of small helium bubbles that act as the predominant sinks for the radiation-induced point defects. (auth)
Date: January 1, 1973
Creator: Santhanam, A.T.
Partner: UNT Libraries Government Documents Department

Analyses and hydrogen-isotope-transport calculations of current and future designs of the LLL rotating-target neutron source

Description: Analyses of the present titanium-tritide RTNS targets are presented. These results include the hydrogen-isotope content of new and used targets, metallography, scanning electron microscopy, and hydrogen-isotope-diffusion calculations using a heat-flow finite-difference computer code. These latter calculations indicate that a combination of long target life and high neutron output is optimized when the rate of hydrogen isotope evolution from the target balances the deposition rate from the beam. Auger spectra show that carbon and oxygen species are present in the bulk and on the surface. (auth)
Date: September 1, 1975
Creator: Steward, S.A.; Nickerson, R. & Booth, R.
Partner: UNT Libraries Government Documents Department

INTERMEDIATE PHASES IN BINARY SYSTEMS OF TECHNETIUM-99 WITH SEVERAL TRANSITION ELEMENTS

Description: An exploratory survey was made of the intermediate phases formed when Tc/ sup 99/ is alloyed with the Sc, Ti, V, Cr, Mn, and Fe-group elements. A total of nineteen intermediate phases were identified and found to be isomorphous with the Cr/sub 3/O-type, CsCl-type, MgZn/sub 2/-type, gamma -phase, or sigma -phase structure. The alloying characteristics of Tc are rationalized in terms of periodic table relationships. (auth)
Date: December 1, 1962
Creator: Darby, Jr, J. B.; Lam, D. J.; Norton, L. J. & Downey, J. W.
Partner: UNT Libraries Government Documents Department

Explosive joints in Nb--Ti/Cu composite superconductors

Description: Explosive welding techniques have been applied to the joining of a Nb-Ti/ Cu composite conductor. Details of the process are given together with mechanical and electrical evaluations of the resulting joints. (auth)
Date: November 1, 1975
Creator: Cornish, D.N.; Zbasnik, J.P. & Pattee, H.E.
Partner: UNT Libraries Government Documents Department

Preparation and extrusion of multifilamentary NbTi conductor billets

Description: In a cooperative program with industrial superconducting wire manufacturers for the purpose of studying billet preparation and extrusion, a total of twenty billets were assembled. Fourteen of these contained no superconductor but were ''dummy'' billets to evaluate methods of stacking to achieve the best packing density. These billets were not extruded but were sectioned transversely and longitudinally for evaluation of billet preparation techniques. The remaining six billets were assembled with NbTi stacking elements in a copper/copper nickel matrix using a standard conductor configuration. Two of these billets were instrumented with thermocouples and used to evaluate preheating techniques. The other four were extruded and drawn to finished conductor size for critical current measurement. This study showed that hexagonal stacking elements, contoured billet jackets and hot isostatic pressing resulted in high density uniform billets for extrusion. Rotary forging was found to be unacceptable for billet compacting. Fast billet heating was achieved in both the salt bath and by induction heating, but the induction method gave a more uniform temperature distribution during the heating cycle. Asymmetry from poor packing density in the billet resulted in nonuniform filament size distributions and poor critical current performance. Billet yield was increased as much as 16 percent by contouring the stacking element positions within the billet. (auth)
Date: January 1, 1975
Creator: Fietz, W.A.; McDonald, R.E. & Miller, J.R.
Partner: UNT Libraries Government Documents Department

Pure tension superconducting toroidal-field coil system design studies for the Argonne Experimental Power Reactor

Description: As part of the Argonne Tokamak Experimental Power Reactor (TEPR) design studies, a toroidal field (TF) coil system has been designed. NbTi was chosen as the most suitable superconductor and 8T was regarded as a practical peak field level in this study. The 16-coil design was chosen as a reasonable compromise between 2 percent field ripple and 3 m access gap. To minimize the coil structure and the bending moments on the conductor, a pure tension coil shape is necessary. A correct approach for determining the pure tension coil profile in a bumpy TF coil system is given. Verification of the pure tension coil by a three- dimensional stress analysis is presented. For coil quench protection, a series- connected scheme is proposed. (auth)
Date: November 1, 1975
Creator: Wang, S.T.; Purcell, J.R.; Demichele, D.W. & Turner, L.R.
Partner: UNT Libraries Government Documents Department

Conductor fabrication for ISABELLE dipole magnets

Description: Fabrication techniques and specifications are discussed for the composite superconductor braids to be used in the dipole magnets of the ISABELLE Storage Rings. Properties of the NbTi and Cu composite superconductor are given, the braid parameters are presented, and the fabrication processes are shown in photographs. (PMA)
Date: January 1, 1975
Creator: McInturff, A.D.
Partner: UNT Libraries Government Documents Department

Effects of precipitation on electron displacement damage in FCC alloys: copper alloys with random and modulated microstructures

Description: Observations on the electron displacement damage behavior of spatially random precipitate in Cu-Co alloys and the modulated structure in Cu-Ti alloys are reported. A few observations of the damage structures in cellularly decomposed Cu-Ti were also made. Results show that (a) metastable quenched solid solution Cu-2wt percent Co alloys, or the same alloys aged to produce coherent Co- rich zones, do not differ greatly from elemental Cu in their behavior under 1 MeV electron irradiation. When the same alloys are aged to form longer incoherent precipitate prior to HVEM irradiation, suppression of the early small loop stage of damage occurs but voids are nucleated in both cases; (b) metastable modulated microstructures in quenched or low temperature aged Cu-4wt percent Ti alloys completely surpressed void nucleation up to fluences on the order of 50 dpa. The very fine scale microstructural changes that occurred during irradiation in the modulated Cu-4wt percent Ti alloys were not resolved in detail, but it appears that the basic difference between Cu-4wt percent Ti and Cu-2wt percent Co was a much larger point defect sink density in the former, resulting in suppression of void nucleation. Since only one irradiation temperature was investigated, namely approximately 300$sup 0$C, these conclusions cannot be taken as a general statement concerning the merits of modulated structures with respect to radiation damage, but the results are encouraging. Certainly microstructural coarsening is to be expected during irradiation if the temperature is much above 350$sup 0$C, and the results may be quite different. (auth)
Date: January 1, 1975
Creator: Carpenter, R.W.
Partner: UNT Libraries Government Documents Department

Experiment to measure the effects of biaxial strain on the critical current of NbTi superconductor

Description: Twisted multifilament, copper-clad NbTi superconductors have been axially and biaxially strained at 4.2K with a 7.5T background field. A simply- constructed cryogenic loading frame was built and used to strain the conductor. Results on 1.27 mm x 3.13 mm conductor have shown that degradation of less than .3 percent of critical current occurred when the wire was biaxially strained to +3260 $mu$epsilon in the axial direction and -1875 $mu$epsilon in the transverse direction. Degradation approaches 3 percent of critical current at approximately 6000 $mu$epsilon in the axial direction only. (auth)
Date: January 1, 1975
Creator: Froelich, K.J.
Partner: UNT Libraries Government Documents Department

The effect of magnetic impurities and barriers on the magnetization and critical current of fine filament NbTi composites

Description: It has been shown that the highest critical currents in fine filament NbTi conductors are obtained when the filaments are closely spaced. However, the filaments in a composite with a high purity copper matrix tend to be coupled via the ''proximity effect'' as the filament spacing is reduced leading to large magnetization at low fields. To reduce the ''proximity'' coupling, trial billets of NbTi have been fabricated with Cu-30% Ni matrix, Cu-0.5% Mn matrix and one with a Ni barrier around the filaments. Wires drawn from these billets have shown that this interfilament coupling can be suppressed for very small filament separations. A full sized commercial billet with Cu-0.5% Mn matrix demonstrates that high J/sub c/ conductors with filament size approx.1 to 5 ..mu..m can be fabricated which show no interfilament coupling at low fields.
Date: January 1, 1987
Creator: Ghosh, A.K.; Sampson, W.B.; Gregory, E.; Kreilick, S. & Wong, J.
Partner: UNT Libraries Government Documents Department