Electronic, structural, and thermodynamic properties of mixed actinide dioxides (U, Pu, Am) O2 from hybrid density functional theory

NASA Astrophysics Data System (ADS)

Ma, Li; Ray, Asok K.

2010-03-01

As a continuation of our studies of pure actinide metals using hybrid density functional theory,footnotetextR. Atta-Fynn and A. K. Ray, Europhysics Letters, 85, 27008-p1- p6 (2009); Chemical Physics Letters, 482, 223-227 (2009). we present here a systematic study of the electronic and geometric structure properties of mixed actinide dioxides, U0.5Pu0.5O2, U0.5Am0.5O2, Pu0.5Am0.5 O2 and U0.8Pu0.2O2. The fraction of exact Hartree-Fock exchange used was 40%. To investigate the effect of spin-orbit coupling on the ground state electronic and geometric structure properties, computations have been carried out at two theoretical levels, one at the scalar-relativistic level with no spin-orbit coupling and one at the fully relativistic level with spin-orbit coupling. Thermodynamic properties have been calculated by a coupling of first-principles calculation and lattice dynamics.

Development of Metallic Fuels for Actinide Transmutation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayes, Steven Lowe; Fielding, Randall Sidney; Benson, Michael Timothy

Research and development activities on metallic fuels are focused on their potential use for actinide transmutation in future sodium fast reactors. As part of this application, there is also a need for a near zero-loss fabrication process and a desire to demonstrate a multifold increase in burnup potential. The incorporation of Am and Np into the traditional U-20Pu-10Zr metallic fuel alloy was demonstrated in the US during the Integral Fast Reactor Program of the 1980’s and early 1990’s. However, the conventional counter gravity injection casting method performed under vacuum, previously used to fabricate these metallic fuel alloys, was not optimizedmore » for mitigating loss of the volatile Am constituent in the casting charge; as a result, approximately 40% of the Am casting charge failed to be incorporated into the as-cast fuel alloys. Fabrication development efforts of the past few years have pursued an optimized bottom-pour casting method to increase utilization of the melted charge to near 100%, and a differential pressure casting approach, performed under an argon overpressure, has been demonstrated to result in essentially no loss of Am due to volatilization during fabrication. In short, a path toward zero-loss fabrication of metallic fuels including minor actinides has been shown to be feasible. Irradiation testing of advanced metallic fuel alloys in the Advanced Test Reactor (ATR) has been underway since 2003. Testing in the ATR is performed inside of cadmium-shrouded positions to remove >99% of the thermal flux incident on the test fuels, resulting in an epi-thermal driven fuel test that is free from gross flux depression and producing an essentially prototypic radial temperature profile inside the fuel rodlets. To date, three irradiation test series (AFC-1,2,3) have been completed. Over 20 different metallic fuel alloys have been tested to burnups as high as 30% with constituent compositions of Pu up to 30%, Am up to 12%, Np up to 10%, and Zr

Unusual behaviour of (Np,Pu)B2C

NASA Astrophysics Data System (ADS)

Klimczuk, Tomasz; Boulet, Pascal; Griveau, Jean-Christophe; Colineau, Eric; Bauer, Ernst; Falmbigl, Matthias; Rogl, Peter; Wastin, Franck

2015-02-01

Two transuranium metal boron carbides, NpB2C and PuB2C have been synthesized by argon arc melting. The crystal structures of the {Np,Pu}B2C compounds were determined from single-crystal X-ray data to be isotypic with the ThB2C-type (space group ?, a = 0.6532(2) nm; c = 1.0769(3) nm for NpB2C and a = 0.6509(2) nm; c = 1.0818(3) nm for PuB2C; Z = 9). Physical properties have been derived from polycrystalline bulk material in the temperature range from 2 to 300 K and in magnetic fields up to 9 T. Magnetic susceptibility and heat capacity data indicate the occurrence of antiferromagnetic ordering for NpB2C with a Neel temperature TN = 68 K. PuB2C is a Pauli paramagnet most likely due to a strong hybridization of s(p,d) electrons with the Pu-5f states. A pseudo-gap, as concluded from the Sommerfeld value and the electronic transport, is thought to be a consequence of the hybridization. The magnetic behaviour of {Np,Pu}B2C is consistent with the criterion of Hill.

U-Zr alloy: XPS and TEM study of surface passivation

NASA Astrophysics Data System (ADS)

Paukov, M.; Tkach, I.; Huber, F.; Gouder, T.; Cieslar, M.; Drozdenko, D.; Minarik, P.; Havela, L.

2018-05-01

Surface reactivity of Uranium metal is an important factor limiting its practical applications. Bcc alloys of U with various transition metals are much less reactive than pure Uranium. So as to specify the mechanism of surface protection, we have been studying the U-20 at.% Zr alloy by photoelectron spectroscopy and transmission electron microscopy. The surface was studied in as-obtained state, in various stages of surface cleaning, and during an isochronal annealing cycle. The analysis based on U-4f, Zr-3p, and O-1 s spectra shows that a Zr-rich phase segregates at the surface at temperatures exceeding 550 K, which provides a self-assembled coating. The comparison of oxygen exposure of the stoichiometric and coated surfaces shows that the coating is efficiently preventing the oxidation of uranium even at elevated temperatures. The coating can be associated with the UZr2+x phase. TEM study indicated that the coating is about 20 nm thick. For the clean state, the U-4f core-level lines of the bcc alloy are practically identical to those of α-U, revealing similar delocalization of the 5f electronic states.

Structure and magnetic properties of amorphous and nanocrystalline Fe 40Co 40Cu 0.5Zr 9Al 2Si 4B 4.5 alloys

NASA Astrophysics Data System (ADS)

Mitra, A.; Kim, H.-Y.; Louzguine, D. V.; Nishiyama, N.; Shen, B.; Inoue, A.

2004-07-01

Crystallisation behaviour and magnetic properties of as-spun and annealed Fe 40Co 40Cu 0.5Zr 9Al 2Si 4B 4.5 alloy have been studied. The annealing was performed at 873 K for 15 min. XRD and TEM studies shows the formation of nanocrystalline α-(Fe,Co)(SiAl) particles with 7.5±2 nm in diameter dispersed in an amorphous matrix. The Curie temperature of the as-spun amorphous ribbon is 736 K. Saturation magnetisation of the annealed sample decreases at a rate of 0.5 emu/g/K in the measured temperature range of 300-1000 K. Excellent room temperature AC magnetic properties are achieved for the nanocrystalline sample. The low value of the imaginary part of the permeability and the high cut-off frequency (20 kHz) suggest that the eddy current contribution in the annealed materials is low. The coercivity of the annealed sample remains almost constant at 95 A/m up to the frequency of 20 kHz. High saturation magnetisation, high Curie temperature and excellent soft magnetic properties in the nanocrystalline state suggests that Fe 40Co 40Cu 0.5Zr 9Al 2Si 4B 4.5 alloy is a strong candidate for high temperature magnetic application.

Comparisons of immersion and electrochemical properties of highly biocompatible Ti-15Zr-4Nb-4Ta alloy and other implantable metals for orthopedic implants

NASA Astrophysics Data System (ADS)

Okazaki, Yoshimitsu; Nagata, Hiroyuki

2012-12-01

Metal release from implantable metals and the properties of oxide films formed on alloy surfaces were analyzed, focusing on the highly biocompatible Ti-15Zr-4Nb-4Ta alloy. The thickness and electrical resistance (Rp) of the oxide film on such an alloy were compared with those of other implantable metals. The quantity of metal released during a 1-week immersion test was considerably smaller for the Ti-15Zr-4Nb-4Ta than the Ti-6Al-4V alloy. The potential (E10) indicating a current density of 10 μA cm-2 estimated from the anodic polarization curve was significantly higher for the Ti-15Zr-4Nb-4Ta than the Ti-6Al-4V alloy and other metals. Moreover, the oxide film (4-7 nm thickness) formed on the Ti-15Zr-4Nb-4Ta surface is electrochemically robust. The oxide film mainly consisted of TiO2 with small amounts of ZrO2, Nb2O5 and Ta2O5 that made the film electrochemically stable. The Rp of Ti-15Zr-4Nb-4Ta was higher than that of Ti-6Al-4V, i.e. 0.9 Ω cm2 in 0.9% NaCl and 1.3 Ω cm2 in Eagle's medium. This Rp was approximately five-fold higher than that of stainless steel, which has a history of more than 40 years of clinical use in the human body. Ti-15Zr-4Nb-4Ta is a potential implant material for long-term clinical use. Moreover, E10 and Rp were found to be useful parameters for assessing biological safety.

Synthesis, Crystal Chemistry, and Physical Properties of Ternary Intermetallic Compounds An2T2X( An=Pu, Am; X=ln, Sn; T=Co, Ir, Ni, Pd, Pt, Rh)

NASA Astrophysics Data System (ADS)

Pereira, L. C. J.; Wastin, F.; Winand, J. M.; Kanellakopoulos, B.; Rebizant, J.; Spirlet, J. C.; Almeida, M.

1997-11-01

The synthesis, structural, and physical characterization of nine new ternary intermetallic compounds belonging to the isostructural An2T2Xfamily with the transuranium Pu and Am elements, namely, Pu 2Ni 2In, Pu 2Pd 2In, Pu 2Pt 2In, Pu 2Rh 2In, Pu 2Ni 2Sn, Pu 2Pd 2Sn, Pu 2Pt 2Sn, Am 2Ni 2Sn, and Am 2Pd 2Sn, are reported. From these compounds only Pu 2Rh 2In, Am 2Ni 2Sn, and Am 2Pd 2Sn melt incongruently. All of these compounds crystallize in a tetragonal U 3Si 2-type structure, with the space group P4/ mbm, ( Z=2) as most of the U and Np 2-2-1 compounds already found. In this structure, Anatoms occupy the 4 h( x1, x1+0.5, 0.5), Tthe 4 g( x2, x2+0.5, 0), and Xthe 2 a(0, 0, 0) positions. The average values of x1and x2are, respectively, 0.17 and 0.37. Single-crystal X-ray data were refined to R/ RW=0.045/0.066, 0.043/0.072, 0.066/0.080, 0.070/0.098, 0.029/0.048, 0.055/0.080, 0.073/0.096, 0.048/0.086, 0.048/0.065 for Pu 2Ni 2In, Pu 2Pd 2In, Pu 2Pt 2In, Pu 2Rh 2In, Pu 2Ni 2Sn, Pu 2Pd 2Sn, Pu 2Pt 2Sn, Am 2Ni 2Sn, and Am 2Pd 2Sn, respectively, for seven variables. The variation of the lattice parameters and the range of stability of the 2-2-1 phase are discussed in terms of the substitution of different An(actinide), T(transition metal), and X( p-electron) elements in their crystal structure. The possible role of spin fluctuations in the low-temperature behavior of the Pu samples is indicated by magnetic and electrical resistivity measurements.

Processing of U-2.5Zr-7.5Nb and U-3Zr-9Nb alloys by sintering process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dos Santos, A. M. M.; Ferraz, W. B.; Lameiras, F. S.

2012-07-01

To minimize the risk of nuclear proliferation, there is worldwide interest in reducing fuel enrichment of research and test reactors. To achieve this objective while still guaranteeing criticality and cycle length requirements, there is need of developing high density uranium metallic fuels. Alloying elements such as Zr, Nb and Mo are added to uranium to improve fuel performance in reactors. In this context, the Centro de Desenvolvimento da Tecnologia Nuclear (CDTN) is developing the U-2.5Zr-7.5Nb and U-3Zr-9Nb (weight %) alloys by the innovative process of sintering that utilizes raw materials in the form of powders. The powders were pressed atmore » 400 MPa and then sintered under a vacuum of about 1x10{sup -4} Torr at temperatures ranging from 1050 deg. to 1500 deg.C. The densities of the alloys were measured geometrically and by hydrostatic method and the phases identified by X ray diffraction (XRD). The microstructures of the pellets were observed by scanning electron microscopy (SEM) and the alloying elements were analyzed by energy dispersive X-ray spectroscopy (EDS). The results obtained showed the fuel density to slightly increase with the sintering temperature. The highest density achieved was approximately 80% of theoretical density. It was observed in the pellets a superficial oxide layer formed during the sintering process. (authors)« less

Multiscale structural characterizations of mixed U(iv)-An(iii) oxalates (An(iii) = Pu or Am) combining XAS and XRD measurements.

PubMed

Arab-Chapelet, B; Martin, P M; Costenoble, S; Delahaye, T; Scheinost, A C; Grandjean, S; Abraham, F

2016-04-28

Mixed actinide(III,IV) oxalates of the general formula M2.2UAn(C2O4)5·nH2O (An = Pu or Am and M = H3O(+) and N2H5(+)) have been quantitatively precipitated by oxalic precipitation in nitric acid medium (yield >99%). Thorough multiscale structural characterization using XRD and XAS measurements confirmed the existence of mixed actinide oxalate solid solutions. The XANES analysis confirmed that the oxidation states of the metallic cations, tetravalent for uranium and trivalent for plutonium and americium, are maintained during the precipitation step. EXAFS measurements show that the local environments around U(+IV), Pu(+III) and Am(+III) are comparable, and the actinides are surrounded by ten oxygen atoms from five bidentate oxalate anions. The mean metal-oxygen distances obtained by XAS measurements are in agreement with those calculated from XRD lattice parameters.

Metallic Fuels Handbook

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janney, Dawn E.; Papesch, Cynthia A.; Burkes, Douglas E.

This is not a typical External Report--It is a Handbook. No Abstract is involved. This includes both Parts 1 and 2. The Metallic Fuels Handbook summarizes currently available information about phases and phase diagrams, heat capacity, thermal expansion, and thermal conductivity of elements and alloys in the U-Pu-Zr-Np-Am-La-Ce-Pr-Nd system. Although many sections are reviews and updates of material in previous versions of the Handbook [1, 2], this revision is the first to include alloys with four or more elements. In addition to presenting information about materials properties, the handbook attempts to provide information about how well each property is knownmore » and how much variation exists between measurements. Although it includes some results from models, its primary focus is experimental data.« less

Study on Ultra-Long Life,Small U-Zr Metallic Fuelled Core With Burnable Poison

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenji Tsuji; Hiromitsu Inagaki; Akira Nishikawa

2002-07-01

A conceptual design for a 50 MWe sodium cooled, U-Pu-Zr metallic fuelled, fast reactor core, which aims at a core lifetime of 30 years, has been performed [1]. As for the compensation for a large burn-up reactivity through 30 years, an axially movable reflector, which is located around the core, carries the major part of it and a burnable poison does the rest. This concept has achieved not only a long core lifetime but also a high discharged burn-up. On this study, a conceptual design for a small fast reactor loading U-Zr metallic fuelled core instead of U-Pu-Zr fuelled coremore » has been conducted, based on the original core arrangement of 4S reactor [2]. Within the range of this study including safety requirements, adopting the burnable poison would be effective to construct a core concept that achieves both a long lifetime and a high discharged burn-up. (authors)« less

Development of spent fuel reprocessing process based on selective sulfurization: Study on the Pu, Np and Am sulfurization

NASA Astrophysics Data System (ADS)

Kirishima, Akira; Amano, Yuuki; Nihei, Toshifumi; Mitsugashira, Toshiaki; Sato, Nobuaki

2010-03-01

For the recovery of fissile materials from spent nuclear fuel, we have proposed a novel reprocessing process based on selective sulfurization of fission products (FPs). The key concept of this process is utilization of unique chemical property of carbon disulfide (CS2), i.e., it works as a reductant for U3O8 but works as a sulfurizing agent for minor actinides and lanthanides. Sulfurized FPs and minor actinides (MA) are highly soluble to dilute nitric acid while UO2 and PuO2 are hardly soluble, therefore, FPs and MA can be removed from Uranium and Plutonium matrix by selective dissolution. As a feasibility study of this new concept, the sulfurization behaviours of U, Pu, Np, Am and Eu are investigated in this paper by the thermodynamical calculation, phase analysis of chemical analogue elements and tracer experiments.

FCRD Advanced Reactor (Transmutation) Fuels Handbook

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janney, Dawn Elizabeth; Papesch, Cynthia Ann

2016-09-01

Transmutation of minor actinides such as Np, Am, and Cm in spent nuclear fuel is of international interest because of its potential for reducing the long-term health and safety hazards caused by the radioactivity of the spent fuel. One important approach to transmutation (currently being pursued by the DOE Fuel Cycle Research & Development Advanced Fuels Campaign) involves incorporating the minor actinides into U-Pu-Zr alloys, which can be used as fuel in fast reactors. U-Pu-Zr alloys are well suited for electrolytic refining, which leads to incorporation rare-earth fission products such as La, Ce, Pr, and Nd. It is, therefore, importantmore » to understand not only the properties of U-Pu-Zr alloys but also those of U-Pu-Zr alloys with concentrations of minor actinides (Np, Am) and rare-earth elements (La, Ce, Pr, and Nd) similar to those in reprocessed fuel. In addition to requiring extensive safety precautions, alloys containing U, Pu, and minor actinides (Np and Am) are difficult to study for numerous reasons, including their complex phase transformations, characteristically sluggish phasetransformation kinetics, tendency to produce experimental results that vary depending on the histories of individual samples, rapid oxidation, and sensitivity to contaminants such as oxygen in concentrations below a hundred parts per million. Although less toxic, rare-earth elements such as La, Ce, Pr, and Nd are also difficult to study for similar reasons. Many of the experimental measurements were made before 1980, and the level of documentation for experimental methods and results varies widely. It is, therefore, not surprising that little is known with certainty about U-Pu-Zr alloys, particularly those that also contain minor actinides and rare-earth elements. General acceptance of results commonly indicates that there is only a single measurement for a particular property. This handbook summarizes currently available information about U, Pu, Zr, Np, Am, La, Ce, Pr, and

Chlorination of UO 2, PuO 2 and rare earth oxides using ZrCl 4 in LiCl-KCl eutectic melt

NASA Astrophysics Data System (ADS)

Sakamura, Yoshiharu; Inoue, Tadashi; Iwai, Takashi; Moriyama, Hirotake

2005-04-01

A new chlorination method using ZrCl 4 in a molten salt bath has been investigated for the pyrometallurgical reprocessing of nuclear fuels. ZrCl 4 has a high reactivity with oxygen but is not corrosive to refractory metals such as steel. Rare earth oxides (La 2O 3, CeO 2, Nd 2O 3 and Y 2O 3) and actinide oxides (UO 2 and PuO 2) were allowed to react with ZrCl 4 in a LiCl-KCl eutectic salt at 773 K to give a metal chloride solution and a precipitate of ZrO 2. An addition of zirconium metal as a reductant was effective in chlorinating the dioxides. When the oxides were in powder form, the reaction was observed to progress rapidly. Cyclic voltammetry provided a convenient way of establishing when the reaction was completed. It was demonstrated that the ZrCl 4 chlorination method, free from corrosive gas, was very simple and useful.

Separation of actinides from irradiated An-Zr based fuel by electrorefining on solid aluminium cathodes in molten LiCl-KCl

NASA Astrophysics Data System (ADS)

Souček, P.; Murakami, T.; Claux, B.; Meier, R.; Malmbeck, R.; Tsukada, T.; Glatz, J.-P.

2015-04-01

An electrorefining process for metallic spent nuclear fuel treatment is being investigated in ITU. Solid aluminium cathodes are used for homogeneous recovery of all actinides within the process carried out in molten LiCl-KCl eutectic salt at a temperature of 500 °C. As the selectivity, efficiency and performance of solid Al has been already shown using un-irradiated An-Zr alloy based test fuels, the present work was focused on laboratory-scale demonstration of the process using irradiated METAPHIX-1 fuel composed of U67-Pu19-Zr10-MA2-RE2 (wt.%, MA = Np, Am, Cm, RE = Nd, Ce, Gd, Y). Different electrorefining techniques, conditions and cathode geometries were used during the experiment yielding evaluation of separation factors, kinetic parameters of actinide-aluminium alloy formation, process efficiency and macro-structure characterisation of the deposits. The results confirmed an excellent separation and very high efficiency of the electrorefining process using solid Al cathodes.

Synthesis and X-ray Crystallography of [Mg(H2O)6][AnO2(C2H5COO)3]2 (An = U, Np, or Pu).

PubMed

Serezhkin, Viktor N; Grigoriev, Mikhail S; Abdulmyanov, Aleksey R; Fedoseev, Aleksandr M; Savchenkov, Anton V; Serezhkina, Larisa B

2016-08-01

Synthesis and X-ray crystallography of single crystals of [Mg(H2O)6][AnO2(C2H5COO)3]2, where An = U (I), Np (II), or Pu (III), are reported. Compounds I-III are isostructural and crystallize in the trigonal crystal system. The structures of I-III are built of hydrated magnesium cations [Mg(H2O)6](2+) and mononuclear [AnO2(C2H5COO)3](-) complexes, which belong to the AB(01)3 crystallochemical group of uranyl complexes (A = AnO2(2+), B(01) = C2H5COO(-)). Peculiarities of intermolecular interactions in the structures of [Mg(H2O)6][UO2(L)3]2 complexes depending on the carboxylate ion L (acetate, propionate, or n-butyrate) are investigated using the method of molecular Voronoi-Dirichlet polyhedra. Actinide contraction in the series of U(VI)-Np(VI)-Pu(VI) in compounds I-III is reflected in a decrease in the mean An═O bond lengths and in the volume and sphericity degree of Voronoi-Dirichlet polyhedra of An atoms.

High temperature investigation of the solid/liquid transition in the PuO2-UO2-ZrO2 system

NASA Astrophysics Data System (ADS)

Quaini, A.; Guéneau, C.; Gossé, S.; Sundman, B.; Manara, D.; Smith, A. L.; Bottomley, D.; Lajarge, P.; Ernstberger, M.; Hodaj, F.

2015-12-01

The solid/liquid transitions in the quaternary U-Pu-Zr-O system are of great interest for the analysis of core meltdown accidents in Pressurised Water Reactors (PWR) fuelled with uranium-dioxide and MOX. During a severe accident the Zr-based cladding can become completely oxidised due to the interaction with the oxide fuel and the water coolant. In this framework, the present analysis is focused on the pseudo-ternary system UO2-PuO2-ZrO2. The melting/solidification behaviour of five pseudo-ternary and one pseudo-binary ((PuO2)0.50(ZrO2)0.50) compositions have been investigated experimentally by a laser heating method under pre-set atmospheres. The effects of an oxidising or reducing atmosphere on the observed melting/freezing temperatures, as well as the amount of UO2 in the sample, have been clearly identified for the different compositions. The oxygen-to-metal ratio is a key parameter affecting the melting/freezing temperature because of incongruent vaporisation effects. In parallel, a detailed thermodynamic model for the UO2-PuO2-ZrO2 system has been developed using the CALPHAD method, and thermodynamic calculations have been performed to interpret the present laser heating results, as well as the high temperature behaviour of the cubic (Pu,U,Zr)O2±x-c mixed oxide phase. A good agreement was obtained between the calculated and experimental data points. This work enables an improved understanding of the major factors relevant to severe accident in nuclear reactors.

Casting evaluation of U-Zr alloy system fuel slug for SFR prepared by injection casting method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Hoon; Kim, Jong-Hwan; Kim, Ki-Hwan

2013-07-01

Metal fuel slugs of U-Pu-Zr alloys for Sodium-cooled Fast Reactor (SFR) have conventionally been fabricated by a vacuum injection casting method. Recently, management of minor actinides (MA) became an important issue because direct disposal of the long-lived MA can be a long-term burden for a tentative repository up to several hundreds of thousand years. In order to recycle transuranic elements (TRU) retained in spent nuclear fuel, remote fabrication capability in a shielded hot cell should be prepared. Moreover, generation of long-lived radioactive wastes and loss of volatile species should be minimized during the recycled fuel fabrication step. In order tomore » prevent the evaporation of volatile elements such as Am, alternative fabrication methods of metal fuel slugs have been studied applying gravity casting, and improved injection casting in KAERI, including melting under inert atmosphere. And then, metal fuel slugs were examined with casting soundness, density, chemical analysis, particle size distribution and microstructural characteristics. Based on these results there is a high level of confidence that Am losses will also be effectively controlled by application of a modest amount of overpressure. A surrogate fuel slug was generally soundly cast by improved injection casting method, melted fuel material under inert atmosphere.« less

Brazing characteristics of a Zr-Ti-Cu-Fe eutectic alloy filler metal for Zircaloy-4

NASA Astrophysics Data System (ADS)

Lee, Jung G.; Lim, C. H.; Kim, K. H.; Park, S. S.; Lee, M. K.; Rhee, C. K.

2013-10-01

A Zr-Ti-Cu-Fe quaternary eutectic alloy was employed as a new Be-free brazing filler metal for Zircaloy-4 to supersede physically vapor-deposited Be coatings used conventionally with several disadvantages. The quaternary eutectic composition of Zr58Ti16Cu10Fe16 (at.%) showing a low melting temperature range from 832 °C to 853 °C was designed by a partial substitution of Zr with Ti based on a Zr-Cu-Fe ternary eutectic system. By applying an alloy ribbon with the determined composition, a highly reliable joint was obtained with a homogeneous formation of predominantly grown α-Zr phases owing to a complete isothermal solidification, exhibiting strength higher than that of Zircaloy-4. The homogenization of the joint was rate-controlled by the diffusion of the filler elements (Ti, Cu, and Fe) into the Zircaloy-4 base metal, and the detrimental segregation of the Zr2Fe phase in the central zone was completely eliminated by an isothermal holding at a brazing temperature of 920 °C for 10 min.

Effect of oxidation state and ionic strength on sorption of actinides (Th, U, Np, Am) to geologic media [Abstract and References Only

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dittrich, Timothy M.; Richmann, Michael K.; Reed, Donald T.

2015-10-30

The degree of conservatism in the estimated sorption partition coefficients (K ds) used in a performance assessment model is being evaluated based on a complementary batch and column method. The main focus of this work is to investigate the role of ionic strength, solution chemistry, and oxidation state (III-VI) in actinide sorption to dolomite rock. Based on redox conditions and solution chemistry expected at the WIPP, possible actinide species include Pu(III), Pu(IV), U(IV), U(VI), Np(IV), Np(V), Am(III), and Th(IV).

Local structure in solid solutions of stabilised zirconia with actinide dioxides (UO{sub 2}, NpO{sub 2})

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walter, Marcus, E-mail: marcus.walter@vkta.d; Somers, Joseph; Bouexiere, Daniel

2011-04-15

The local structure of (Zr,Lu,U)O{sub 2-x} and (Zr,Y,Np)O{sub 2-x} solid solutions has been investigated by extended X-ray absorption fine structure (EXAFS). Samples were prepared by mixing reactive (Zr,Lu)O{sub 2-x} and (Zr,Y)O{sub 2-x} precursor materials with the actinide oxide powders, respectively. Sintering at 1600 {sup o}C in Ar/H{sub 2} yields a fluorite structure with U(IV) and Np(IV). As typical for stabilised zirconia the metal-oxygen and metal-metal distances are characteristic for the different metal ions. The bond lengths increase with actinide concentration, whereas highest adaptation to the bulk stabilised zirconia structure was observed for U---O and Np---O bonds. The Zr---O bond showsmore » only a slight increase from 2.14 A at 6 mol% actinide to 2.18 A at infinite dilution in UO{sub 2} and NpO{sub 2}. The short interatomic distance between Zr and the surrounding oxygen and metal atoms indicate a low relaxation of Zr with respect to the bulk structure, i.e. a strong Pauling behaviour. -- Graphical abstract: Metal-oxygen bond distances in (Zr,Lu,U)O{sub 2-x} solid solutions with different oxygen vacancy concentrations (Lu/Zr=1 and Lu/Zr=0.5). Display Omitted Research Highlights: {yields} EXAFS indicates high U and Np adaption to the bulk structure of stabilised zirconia. {yields} Zr---O bond length is 2.18 A at infinite Zr dilution in UO{sub 2} and NpO{sub 2}. {yields} Low relaxation (strong Pauling behaviour) of Zr explains its low solubility in UO{sub 2}.« less

U-PuO2, U-PuC, U-PuN cermet fuel for fast reactor

NASA Astrophysics Data System (ADS)

Mishra, Sudhir; Kaity, Santu; Banerjee, Joydipta; Nandi, Chiranjeet; Dey, G. K.; Khan, K. B.

2018-02-01

Cermet fuel combines beneficial properties of both ceramic and metal and attracts global interest for research as a candidate fuel for nuclear reactors. In the present study, U matrix PuC/PuN/PuO2 cermet for fast reactor have been fabricated on laboratory scale by the powder metallurgy route. Characterization of the fuel has been carried out using Dilatometer, Differential Thermal analysis (DTA), X-ray diffractometer and Optical microscope. X ray diffraction study of the fuel reveals presence of different phases. The PuN dispersed cermet was observed to have high solidus temperature as compared to PuC and PuO2 dispersed cermet. Swelling was observed in U matrix PuO2 cermet which also showed higher thermal expansion. Among the three cermets studied, U matrix PuC cermet showed maximum thermal conductivity.

Diffusion Barrier Selection from Refractory Metals (Zr, Mo and Nb) via Interdiffusion Investigation for U-Mo RERTR Fuel Alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

K. Huang; C. Kammerer; D. D. Keiser, Jr.

2014-04-01

U-Mo alloys are being developed as low enrichment monolithic fuel under the Reduced Enrichment for Research and Test Reactor (RERTR) Program. Diffusional interactions between the U-Mo fuel alloy and Al-alloy cladding within the monolithic fuel plate construct necessitate incorporation of a barrier layer. Fundamentally, a diffusion barrier candidate must have good thermal conductivity, high melting point, minimal metallurgical interaction, and good irradiation performance. Refractory metals, Zr, Mo, and Nb are considered based on their physical properties, and the diffusion behavior must be carefully examined first with U-Mo fuel alloy. Solid-to-solid U-10wt.%Mo vs. Mo, Zr, or Nb diffusion couples were assembledmore » and annealed at 600, 700, 800, 900 and 1000 degrees C for various times. The interdiffusion microstructures and chemical composition were examined via scanning electron microscopy and electron probe microanalysis, respectively. For all three systems, the growth rate of interdiffusion zone were calculated at 1000, 900 and 800 degrees C under the assumption of parabolic growth, and calculated for lower temperature of 700, 600 and 500 degrees C according to Arrhenius relationship. The growth rate was determined to be about 10 3 times slower for Zr, 10 5 times slower for Mo and 10 6 times slower for Nb, than the growth rates reported for the interaction between the U-Mo fuel alloy and pure Al or Al-Si cladding alloys. Zr, however was selected as the barrier metal due to a concern for thermo- mechanical behavior of UMo/Nb interface observed from diffusion couples, and for ductile-to-brittle transition of Mo near room temperature.« less

Static electric dipole polarizabilities of tri- and tetravalent U, Np, and Pu ions.

PubMed

Parmar, Payal; Peterson, Kirk A; Clark, Aurora E

2013-11-21

High-quality static electric dipole polarizabilities have been determined for the ground states of the hard-sphere cations of U, Np, and Pu in the III and IV oxidation states. The polarizabilities have been calculated using the numerical finite field technique in a four-component relativistic framework. Methods including Fock-space coupled cluster (FSCC) and Kramers-restricted configuration interaction (KRCI) have been performed in order to account for electron correlation effects. Comparisons between polarizabilities calculated using Dirac-Hartree-Fock (DHF), FSCC, and KRCI methods have been made using both triple- and quadruple-ζ basis sets for U(4+). In addition to the ground state, this study also reports the polarizability data for the first two excited states of U(3+/4+), Np(3+/4+), and Pu(3+/4+) ions at different levels of theory. The values reported in this work are the most accurate to date calculations for the dipole polarizabilities of the hard-sphere tri- and tetravalent actinide ions and may serve as reference values, aiding in the calculation of various electronic and response properties (for example, intermolecular forces, optical properties, etc.) relevant to the nuclear fuel cycle and material science applications.

Ferro- and antiferro-magnetism in (Np, Pu)BC

NASA Astrophysics Data System (ADS)

Klimczuk, T.; Shick, A. B.; Kozub, A. L.; Griveau, J.-C.; Colineau, E.; Falmbigl, M.; Wastin, F.; Rogl, P.

2015-04-01

Two new transuranium metal boron carbides, NpBC and PuBC, have been synthesized. Rietveld refinements of powder XRD patterns of {Np,Pu}BC confirmed in both cases isotypism with the structure type of UBC. Temperature dependent magnetic susceptibility data reveal antiferromagnetic ordering for PuBC below TN = 44 K, whereas ferromagnetic ordering was found for NpBC below TC = 61 K. Heat capacity measurements prove the bulk character of the observed magnetic transition for both compounds. The total energy electronic band structure calculations support formation of the ferromagnetic ground state for NpBC and the antiferromagnetic ground state for PuBC.

Static electric dipole polarizabilities of An(5+/6+) and AnO2 (+/2+) (An = U, Np, and Pu) ions.

PubMed

Parmar, Payal; Peterson, Kirk A; Clark, Aurora E

2014-12-21

The parallel components of static electric dipole polarizabilities have been calculated for the lowest lying spin-orbit states of the penta- and hexavalent oxidation states of the actinides (An) U, Np, and Pu, in both their atomic and molecular diyl ion forms (An(5+/6+) and AnO2 (+/2+)) using the numerical finite-field technique within a four-component relativistic framework. The four-component Dirac-Hartree-Fock method formed the reference for MP2 and CCSD(T) calculations, while multireference Fock space coupled-cluster (FSCC), intermediate Hamiltonian Fock space coupled-cluster (IH-FSCC) and Kramers restricted configuration interaction (KRCI) methods were used to incorporate additional electron correlation. It is observed that electron correlation has significant (∼5 a.u.(3)) impact upon the parallel component of the polarizabilities of the diyls. To the best of our knowledge, these quantities have not been previously reported and they can serve as reference values in the determination of various electronic and response properties (for example intermolecular forces, optical properties, etc.) relevant to the nuclear fuel cycle and material science applications. The highest quality numbers for the parallel components (αzz) of the polarizability for the lowest Ω levels corresponding to the ground electronic states are (in a.u.(3)) 44.15 and 41.17 for UO2 (+) and UO2 (2+), respectively, 45.64 and 41.42 for NpO2 (+) and NpO2 (2+), respectively, and 47.15 for the PuO2 (+) ion.

Deviation between the chemistry of Ce(IV) and Pu(IV) and routes to ordered and disordered heterobimetallic 4f/5f and 5f/5f phosphonates.

PubMed

Diwu, Juan; Wang, Shuao; Good, Justin J; DiStefano, Victoria H; Albrecht-Schmitt, Thomas E

2011-06-06

The heterobimetallic actinide compound UO(2)Ce(H(2)O)[C(6)H(4)(PO(3)H)(2)](2)·H(2)O was prepared via the hydrothermal reaction of U(VI) and Ce(IV) in the presence of 1,2-phenylenediphosphonic acid. We demonstrate that this is a kinetic product that is not stable with respect to decomposition to the monometallic compounds. Similar reactions have been explored with U(VI) and Ce(III), resulting in the oxidation of Ce(III) to Ce(IV) and the formation of the Ce(IV) phosphonate, Ce[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O, UO(2)Ce(H(2)O)[C(6)H(4)(PO(3)H)(2)](2)·H(2)O, and UO(2)[C(6)H(4)(PO(3)H)(2)](H(2)O)·H(2)O. In comparison, the reaction of U(VI) with Np(VI) only yields Np[C(6)H(4)(PO(3)H)(2)](2)·2H(2)O and aqueous U(VI), whereas the reaction of U(VI) with Pu(VI) yields the disordered U(VI)/Pu(VI) compound, (U(0.9)Pu(0.1))O(2)[C(6)H(4)(PO(3)H)(2)](H(2)O)·H(2)O, and the Pu(IV) phosphonate, Pu[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O. The reactions of Ce(IV) with Np(VI) yield disordered heterobimetallic phosphonates with both M[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O (M = Ce, Np) and M[C(6)H(4)(PO(3)H)(2)](2)·2H(2)O (M = Ce, Np) structures, as well as the Ce(IV) phosphonate Ce[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O. Ce(IV) reacts with Pu(IV) to yield the Pu(VI) compound, PuO(2)[C(6)H(4)(PO(3)H)(2)](H(2)O)·3H(2)O, and a disordered heterobimetallic Pu(IV)/Ce(IV) compound with the M[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O (M = Ce, Pu) structure. Mixtures of Np(VI) and Pu(VI) yield disordered heterobimetallic Np(IV)/Pu(IV) phosphonates with both the An[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O (M = Np, Pu) and An[C(6)H(4)(PO(3)H)(2)](2)·2H(2)O (M = Np, Pu) formulas. © 2011 American Chemical Society

Multiple deformation mechanisms of Ti-22.4Nb-0.73Ta-2.0Zr-1.34O alloy

NASA Astrophysics Data System (ADS)

Yang, Y.; Li, G. P.; Cheng, G. M.; Li, Y. L.; Yang, K.

2009-02-01

Ti-22.4Nb-0.73Ta-2.0Zr-1.34O (at. %) alloy after cold compression to ˜5.2% strain was investigated. The alloy exhibited multiple plastic deformation mechanisms, including the stress-induced α″ martensitic (SIM α″) and ω phase transformations, 1/2⟨111⟩ dislocations slipping on the {112}β planes as well as {332}⟨113⟩β and {112}⟨111⟩β twinning, which have not previously been reported to coexist in a titanium alloy. It was also found that β phase with the {200} planes vertical to the compression direction was almost completely consumed away by a β →SIM α″ transformation, and a (100) texture of SIM α″ formed.

Identification of NpO2+x in the binary Np-O system

NASA Astrophysics Data System (ADS)

Tayal, Akhil; Conradson, Steven D.; Baldinozzi, Gianguido; Namdeo, Sonu; Roberts, Kevin E.; Allen, Patrick G.; Shuh, David K.

2017-07-01

In contrast to UO2 and PuO2, there is no consensus on the existence of mixed valence NpO2+x, resulting in a gap between NpO2 and Np2O5 (the highest binary oxide of Np) in the Np-O phase diagram. We now show NpO2+x via Np LIII Extended X-ray Absorption Fine Structure (EXAFS) spectra of three samples of NpO2 that, analogous to U and Pu, exhibit multisite Np-O distributions with varying numbers of oxygen atoms at 1.87-1.91 Å. This is supported by the diffraction pattern of the sample with the largest amount of this oxo-type species that can be refined with both the simple fluorite structure and a trigonal one related to α-U4O9. The implied Np(V)-bridging oxo moieties as well as possible indications of OHbar found by detailed EXAFS analysis suggest that NpO2+x more closely resembles PuO2+x than UO2+x. An additional common characteristic suggested by the EXAFS and X-Ray Diffraction (XRD) is the phase separation into NpO2 and what would be previously unreported Np4O9(-δ), indicative of O clustering.

Electrochemical corrosion, wear and cell behavior of ZrO2/TiO2 alloyed layer on Ti-6Al-4V.

PubMed

Li, Jianfang; He, Xiaojing; Zhang, Guannan; Hang, Ruiqiang; Huang, Xiaobo; Tang, Bin; Zhang, Xiangyu

2018-06-01

Ti-6Al-4V (TC4) has received increasing attention as biomaterial but also raised concerns about the long-term safety of releasing of metal ions and poor wear resistance. In this work, an ZrO 2 /TiO 2 alloyed layer was prepared on TC4 by plasma surface alloying with Zr and subsequently annealed in the air for improved corrosion and wear resistant. To assess the corrosion performance of the alloyed layer, the specimens were measured by open circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization in simulated body fluid solution. The result shows that the ZrO 2 /TiO 2 alloyed layer exhibits strikingly high polarization resistance, wide passive region and very low current density, indicating the excellent corrosion resistance. The layer also displays significant improvement of wear resistance. Furthermore, the alloyed layer restricts cell adhesion and spreading. We infer that the ZrO 2 /TiO 2 alloyed layer might be potentially useful implanted devices such as biosensors, bioelectronics or drug delivery devices. Copyright © 2018 Elsevier B.V. All rights reserved.

U, Pu, and Am nuclear signatures of the Thule hydrogen bomb debris.

PubMed

Eriksson, Mats; Lindahl, Patric; Roos, Per; Dahlgaard, Henning; Holm, Elis

2008-07-01

This study concerns an arctic marine environment that was contaminated by actinide elements after a nuclear accident in 1968, the so-called Thule accident In this study we have analyzed five isolated hot particles as well as sediment samples containing particles from the weapon material for the determination of the nuclear fingerprint of the accident. We report that the fissile material in the hydrogen weapons involved in the Thule accident was a mixture of highly enriched uranium and weapon-grade plutonium and that the main fissile material was 235U (about 4 times more than the mass of 239Pu). In the five hot particles examined, the measured uranium atomic ratio was 235U/238U = 1.02 +/- 0.16 and the Pu-isotopic ratios were as follows: 24Pu/239Pu = 0.0551 +/- 0.0008 (atom ratio), 238Pu/239+240Pu = 0.0161 +/- 0.0005 (activity ratio), 241Pu/239+240Pu = 0.87 +/- 0.12 (activity ratio), and 241Am/ 239+240Pu = 0.169 +/- 0.005 (activity ratio) (reference date 2001-10-01). From the activity ratios of 241Pu/241Am, we estimated the time of production of this weapon material to be from the late 1950s to the early 1960s. The results from reanalyzed bulk sediment samples showed the presence of more than one Pu source involved in the accident, confirming earlier studies. The 238Pu/239+240PU activity ratio and the 240Pu/ 239Pu atomic ratio were divided into at least two Pu-isotopic ratio groups. For both Pu-isotopic ratios, one ratio group had identical ratios as the five hot particles described above and for the other groups the Pu isotopic ratios were lower (238Pu/ 239+240PU activity ratio approximately 0.01 and the 240Pu/P239Pu atomic ratio 0.03). On the studied particles we observed that the U/Pu ratio decreased as a function of the time these particles were present in the sediment. We hypothesis that the decrease in the ratio is due to a preferential leaching of U relative to Pu from the particle matrix.

Electrodeposition of hydroxyapatite coating on Mg-4.0Zn-1.0Ca-0.6Zr alloy and in vitro evaluation of degradation, hemolysis, and cytotoxicity.

PubMed

Guan, Ren-Guo; Johnson, Ian; Cui, Tong; Zhao, Tong; Zhao, Zhan-Yong; Li, Xue; Liu, Huinan

2012-04-01

A novel biodegradable Mg-4.0Zn-1.0Ca-0.6Zr (wt %) alloy was successfully produced using a series of metallurgical processes; including melting, casting, rolling, and heat treatment. The hardness and ultimate tensile strength of the alloy sheets increased to 71.2HV and 320 MPa after rolling and then aging for 12 h at 175°C. These mechanical properties were sufficient for load-bearing orthopedic implants. A hydroxyapatite (HA) coating was deposited on the Mg-4.0Zn-1.0Ca-0.6Zr (wt %) alloy using a novel coating process combining alkali heat pretreatment, electrodeposition, and alkali heat posttreatment. The microstructure, composition, and phases of the Mg-4.0Zn-1.0Ca-0.6Zr (wt %) alloy and HA coating were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). The degradation, hemolysis, and cytocompatibility of the HA-coated and uncoated Mg-4.0Zn-1.0Ca-0.6Zr (wt %) alloy were studied in vitro. The corrosion potential (E(corr)) of Mg-4.0Zn-1.0Ca-0.6Zr alloy (-1.72 V) was higher than Mg (-1.95 V), Mg-0.6Ca alloy (-1.91 V) and Mg-1.0Ca alloy (-1.97 V), indicating the Mg-Zn-Ca-Zr alloy would be more corrosion resistant. The initial corrosion potential of the HA-coated Mg alloy sample (-1.51 V) was higher than the uncoated sample (-1.72 V). The hemolysis rates of the HA-coated and uncoated Mg-4.0Zn-1.0Ca-0.6Zr (wt %) alloy samples were both <5%, which met the requirements for implant materials. The HA-coated and uncoated Mg-4.0Zn-1.0Ca-0.6Zr (wt %) alloy samples demonstrated the same cytotoxicity score as the negative control. The HA-coated samples showed a slightly greater relative growth rate (RGR%) of fibroblasts than the uncoated samples. Both the HA-coated and uncoated Mg-4.0Zn-1.0Ca-0.6Zr (wt %) alloy provided evidence of acceptable cytocompatibility for medical applications. Copyright © 2012 Wiley Periodicals, Inc.

Covalency in the f element-chalcogen bond. computational studies of M[N(EPR2)2]3 (M = La, Ce, Pr, Pm, Eu, U, Np, Pu, Am, Cm; E = O, S, Se, Te; R = H, (i)Pr, Ph).

PubMed

Ingram, Kieran I M; Tassell, Matthew J; Gaunt, Andrew J; Kaltsoyannis, Nikolas

2008-09-01

The geometric and electronic structures of the title complexes have been studied using scalar relativistic, gradient-corrected density functional theory. Extension of our previous work on six-coordinate M[N(EPH 2) 2] 3 (M = La, Ce, U, Pu; E = O, S, Se, Te), models for the experimentally characterized M[N(EP (i)Pr 2) 2] 3, yields converged geometries for all of the other 4f and 5f metals studied and for all four group 16 elements. By contrast, converged geometries for nine-coordinate M[N(EPPh 2) 2] 3 are obtained only for E = S and Se. Comparison of the electronic structures of six- and nine-coordinate M[N(EPH 2) 2] 3 suggests that coordination of the N atoms produces only minor changes in the metal-chalcogen interactions. Six-coordinate Eu[N(EPH 2) 2] 3 and Am[N(EPH 2) 2] 3 with the heavier group 16 donors display geometric and electronic properties rather different from those of the other members of the 4f and 5f series, in particular, longer than expected Eu-E and Am-E bond lengths, smaller reductions in charge difference between M and E down group 16, and larger f populations. The latter are interpreted not as evidence of f-based metal-ligand covalency but rather as being indicative of ionic metal centers closer to M (II) than M (III). The Cm complexes are found to be very ionic, with very metal-localized f orbitals and Cm (III) centers. The implications of the results for the separation of the minor actinides from nuclear wastes are discussed, as is the validity of using La (III)/U (III) comparisons as models for minor actinide/Eu systems.

The fission cross sections of /sup 230/Th, /sup 232/Th, /sup 233/U, /sup 234/U, /sup 236/U, /sup 238/U, /sup 237/Np, /sup 239/Pu and /sup 242/Pu relative /sup 235/U at 14. 74 MeV neutron energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meadows, J.W.

1986-12-01

The measurement of the fission cross section ratios of nine isotopes relative to /sup 235/U at an average neutron energy of 14.74 MeV is described with particular attention to the determination of corrections and to sources of error. The results are compared to ENDF/B-V and to other measurements of the past decade. The ratio of the neutron induced fission cross section for these isotopes to the fission cross section for /sup 235/U are: /sup 230/Th - 0.290 +- 1.9%; /sup 232/Th - 0.191 +- 1.9%; /sup 233/U - 1.132 +- 0.7%; /sup 234/U - 0.998 +- 1.0%; /sup 236/U -more » 0.791 +- 1.1%; /sup 238/U - 0.587 +- 1.1%; /sup 237/Np - 1.060 +- 1.4%; /sup 239/Pu - 1.152 +- 1.1%; /sup 242/Pu - 0.967 +- 1.0%. 40 refs., 11 tabs., 9 figs.« less

Effect of thermo-mechanical processing on microstructure and mechanical properties of U - Nb - Zr alloys: Part 2 - U - 3 wt % Nb - 9 wt % Zr and U - 9 wt% Nb - 3 wt% Zr

NASA Astrophysics Data System (ADS)

Morais, Nathanael Wagner Sales; Lopes, Denise Adorno; Schön, Cláudio Geraldo

2018-04-01

The present work is the second and final part of an extended investigation on Usbnd Nb - Zr alloys. It investigates the effect of mechanical processing routes on microstructure of alloys U - 3 wt % Nb - 9 wt % Zr and U - 9 wt% Nb - 3 wt% Zr, through X-ray diffraction and scanning electron microscopy, completing the investigation, which started with alloy U - 6 wt% Nb - 6 wt% Zr in part 1. Mechanical properties are determined using microhardness and bending tests and correlated with the developed microstructures. The results show that processing sequence, in particular the inclusion of a 1000 °C heat treatment step, affects significantly the microstructure and mechanical properties of these alloys alloy in different ways. Microstructural characterization shows that both alloys present significant volume fraction of precipitates of a body-centered cubic (BCC) γ-Nb-Zr rich phase in addition the uranium-rich matrix. Bending tests show that sample ductility does not correlate necessarily with hardness and that the key factor appears to be the amount of the γ-Nb-Zr precipitates, which controls the matrix microstructure. Samples with a monoclinic α″ cellular microstructure and/or with the tetragonally-distorted BCC phase (γ0), although not strictly ductile, showed the largest allowed strains-before-break and complete elastic recovery of the broken pieces, pointing out to the macroscopic observation of superelasticity.

Simulation of Zr content in TiZrCuNi brazing filler metal for Ti6Al4V alloy

NASA Astrophysics Data System (ADS)

Yue, Xishan; Xie, Zonghong; Jing, Yongjuan

2017-07-01

To optimize the Zr content in Ti-based filler metal, the covalent electron on the nearest atoms bond in unit cell ( n A u-v ) with Ti-based BCC structure was calculated, in which the brazing temperature was considered due to its influence on the lattice parameter. Based on EET theory (The Empirical Electron Theory for solid and molecules), n_{{A}}^{{u - v}} represents the strength of the unit cell with defined element composition and structure, which reflects the effect from solid solution strengthening on the strength of the unit cell. For Ti-Zr-15Cu-10Ni wt% filler metal, it kept constant as 0.3476 with Zr as 37.5˜45 wt% and decreased to 0.333 with Zr decreasing from 37.5 to 25 wt%. Finally, it increased up to 0.3406 with Zr as 2˜10 wt%. Thus, Ti-based filler metal with Zr content being 2˜10 wt% is suggested based on the simulation results. Moreover, the calculated covalent electron of n A u-v showed good agreement with the hardness of the joint by filler 37.5Zr and 10Zr. The composition of Ti-10Zr-15Cu-10Ni wt% was verified in this study with higher tensile strength of the brazing joint and uniform microstructure of the interface.

Electron correlation and relativity of the 5f electrons in the U-Zr alloy system

NASA Astrophysics Data System (ADS)

Söderlind, P.; Sadigh, B.; Lordi, V.; Landa, A.; Turchi, P. E. A.

2014-01-01

-of-states (DOS) for α-U with and without SOC. Most of the difference occurs well above the Fermi level, and this also explains why SOC is more important for the heavier metals Pu and Am [12]. Because of the very small influence of SOC on V and B for γ-U, one may argue that also the formation enthalpies for the U-Zr system, that substantially depend on these properties, are insensitive to the SOC, contrary to the conclusion by Xiong et al. [1].Next, we address the issue of strong electron correlation and the need for an LSDA + U type of approach for γ-uranium. Searching through the literature we could not find any publication where the LSDA + U methodology was applied to uranium metal, except that of [1], but for uranium oxides they are plentiful. However, we found that it has been considered for its nearest-neighbor metals Pa [13] and Np [14] (U lies between them in the periodic table). These publications suggest that LSDA + U are not necessary for the metals while for their oxides it is relevant, although the methodology itself is phenomenological. Focusing first on the uranium ground state, orthorhombic α-U, equilibrium and structural properties [11], elastic constants [11,15], phonon spectra [16], various defects [17-19], and even subtle electronic-structure details related to the charge-density waves [20] are all satisfactorily described within conventional DFT. These results clearly imply that LSDA + U are not a relevant or necessary scheme for α-uranium. How about the high-temperature γ phase?The γ phase is stable at temperatures above 1100 K and it has a significantly larger volume than α-U, see Table 1. One may suspect that this is due to f-electron localization (strong f-electron correlation), but it actually stems from normal thermal volume expansion.In Fig. 2 we show the calculated α-U thermal volume expansion, using a parameter-free Debye-Grüneisen quasi-harmonic theory [21,22]. Also included are experimental data points taken from Donohue [23]. The good

Effect of Surface Modifications of Ti40Zr10Cu38Pd12 Bulk Metallic Glass and Ti-6Al-4V Alloy on Human Osteoblasts In Vitro Biocompatibility

PubMed Central

Blanquer, Andreu; Hynowska, Anna; Nogués, Carme; Ibáñez, Elena; Sort, Jordi; Baró, Maria Dolors; Özkale, Berna; Pané, Salvador; Pellicer, Eva

2016-01-01

The use of biocompatible materials, including bulk metallic glasses (BMGs), for tissue regeneration and transplantation is increasing. The good mechanical and corrosion properties of Ti40Zr10Cu38Pd12 BMG and its previously described biocompatibility makes it a potential candidate for medical applications. However, it is known that surface properties like topography might play an important role in regulating cell adhesion, proliferation and differentiation. Thus, in the present study, Ti40Zr10Cu38Pd12 BMG and Ti6-Al-4V alloy were surface-modified electrochemically (nanomesh) or physically (microscratched) to investigate the effect of material topography on human osteoblasts cells (Saos-2) adhesion, proliferation and differentiation. For comparative purposes, the effect of mirror-like polished surfaces was also studied. Electrochemical treatments led to a highly interconnected hierarchical porous structure rich in oxides, which have been described to improve corrosion resistance, whereas microscratched surfaces showed a groove pattern with parallel trenches. Cell viability was higher than 96% for the three topographies tested and for both alloy compositions. In all cases, cells were able to adhere, proliferate and differentiate on the alloys, hence indicating that surface topography plays a minor role on these processes, although a clear cell orientation was observed on microscratched surfaces. Overall, our results provide further evidence that Ti40Zr10Cu38Pd12 BMG is an excellent candidate, in the present two topographies, for bone repair purposes. PMID:27243628

Chemical resolution of Pu+ from U+ and Am+ using a band-pass reaction cell inductively coupled plasma mass spectrometer.

PubMed

Tanner, Scott D; Li, Chunsheng; Vais, Vladimir; Baranov, Vladimir I; Bandura, Dmitry R

2004-06-01

Determination of the concentration and distribution of the Pu and Am isotopes is hindered by the isobaric overlaps between the elements themselves and U, generally requiring time-consuming chemical separation of the elements. A method is described in which chemical resolution of the elemental ions is obtained through ion-molecule reactions in a reaction cell of an ICPMS instrument. The reactions of "natural" U(+), (242)Pu(+), and (243)Am(+) with ethylene, carbon dioxide, and nitric oxide are reported. Since the net sensitivities to the isotopes of an element are similar, chemical resolution is inferred when one isobaric element reacts rapidly with a given gas and the isobar (or in this instance surrogate isotope) is unreactive or slowly reactive. Chemical resolution of the m/z 238 isotopes of U and Pu can be obtained using ethylene as a reaction gas, but little improvement in the resolution of the m/z 239 isobars is obtained. However, high efficiency of reaction of U(+) and UH(+) with CO(2), and nonreaction of Pu(+), allows the sub-ppt determination of (239)Pu, (240)Pu, and (242)Pu (single ppt for (238)Pu) in the presence of 7 orders of magnitude excess U matrix without prior chemical separation. Similarly, oxidation of Pu(+) by NO, and nonreaction of Am(+), permit chemical resolution of the isobars of Pu and Am over 2-3 orders of magnitude relative concentration. The method provides the potential for analysis of the actinides with reduced sample matrix separation.

Increasing Ti-6Al-4V brazed joint strength equal to the base metal by Ti and Zr amorphous filler alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ganjeh, E., E-mail: navidganjehie@sina.kntu.ac.ir; Sarkhosh, H.; Bajgholi, M.E.

Microstructural features developed along with mechanical properties in furnace brazing of Ti-6Al-4V alloy using STEMET 1228 (Ti-26.8Zr-13Ni-13.9Cu, wt.%) and STEMET 1406 (Zr-9.7Ti-12.4Ni-11.2Cu, wt.%) amorphous filler alloys. Brazing temperatures employed were 900-950 Degree-Sign C for the titanium-based filler and 900-990 Degree-Sign C for the zirconium-based filler alloys, respectively. The brazing time durations were 600, 1200 and 1800 s. The brazed joints were evaluated by ultrasonic test, and their microstructures and phase constitutions analyzed by metallography, scanning electron microscopy and X-ray diffraction analysis. Since microstructural evolution across the furnace brazed joints primarily depends on their alloying elements such as Cu, Ni andmore » Zr along the joint. Accordingly, existence of Zr{sub 2}Cu, Ti{sub 2}Cu and (Ti,Zr){sub 2}Ni intermetallic compounds was identified in the brazed joints. The chemical composition of segregation region in the center of brazed joints was identical to virgin filler alloy content which greatly deteriorated the shear strength of the joints. Adequate brazing time (1800 s) and/or temperature (950 Degree-Sign C for Ti-based and 990 Degree-Sign C for Zr-based) resulted in an acicular Widmanstaetten microstructure throughout the entire joint section due to eutectoid reaction. This microstructure increased the shear strength of the brazed joints up to the Ti-6Al-4V tensile strength level. Consequently, Ti-6Al-4V can be furnace brazed by Ti and Zr base foils produced excellent joint strengths. - Highlights: Black-Right-Pointing-Pointer Temperature or time was the main factors of controlling braze joint strength. Black-Right-Pointing-Pointer Developing a Widmanstaetten microstructure generates equal strength to base metal. Black-Right-Pointing-Pointer Brittle intermetallic compounds like (Ti,Zr){sub 2}Ni/Cu deteriorate shear strength. Black-Right-Pointing-Pointer Ti and Zr base filler alloys were the best choice for

Structure, mechanical properties, and grindability of dental Ti-Zr alloys.

PubMed

Ho, Wen-Fu; Chen, Wei-Kai; Wu, Shih-Ching; Hsu, Hsueh-Chuan

2008-10-01

Structure, mechanical properties and grindability of a series of binary Ti-Zr alloys with zirconium contents ranging from 10 to 40 wt% have been investigated. Commercially pure titanium (c.p. Ti) was used as a control. Experimental results indicated that the diffraction peaks of all the Ti-Zr alloys matched those for alpha Ti. No beta-phase peaks were found. The hardness of the Ti-Zr alloys increased as the Zr contents increased, and ranged from 266 HV (Ti-10Zr) to 350 HV (Ti-40Zr). As the concentration of zirconium in the alloys increased, the strength, elastic recovery angles and hardness increased. Moreover, the elastically recoverable angle of Ti-40Zr was higher than of c.p. Ti by as much as 550%. The grindability of each metal was found to be largely dependent on the grinding conditions. The Ti-40Zr alloy had a higher grinding rate and grinding ratio than c.p. Ti at low speed. The grinding rate of the Ti-40Zr alloy at 500 m/min was about 1.8 times larger than that of c.p. Ti, and the grinding ratio was about 1.6 times larger than that of c.p. Ti. Our research suggested that the Ti-40Zr alloy has better mechanical properties, excellent elastic recovery capability and improved grindability at low grinding speed. The Ti-40Zr alloy has a great potential for use as a dental machining alloy.

Microstructural characterization of annealed U-12Zr-4Pd and U-12Zr-4Pd-5Ln: Investigating Pd as a metallic fuel additive

NASA Astrophysics Data System (ADS)

Benson, Michael T.; He, Lingfeng; King, James A.; Mariani, Robert D.

2018-04-01

Palladium is being investigated as a potential additive to metallic fuel to control fuel-cladding chemical interaction (FCCI). A primary cause of FCCI is the lanthanide fission products moving to the fuel periphery and interacting with the cladding. This interaction will lead to wastage of the cladding and, given enough time or burn-up, eventually to a cladding breach. The current study is a scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterization of annealed U-12Zr-4Pd and U-12Zr-4Pd-5Ln, where Ln = 53Nd-25Ce-16Pr-6La. The present study shows that Pd preferentially binds the lanthanides over other fuel constituents, which may prevent lanthanide migration and interaction with the cladding during irradiation. The SEM analysis indicates the 1:1 Pd-Ln compound is being formed, while the TEM analysis, due to higher resolution, found the 1:1 compound, as well as Pd-rich compounds Pd2Ln and Pd3Ln2.

Novel Ti-Ta-Hf-Zr alloys with promising mechanical properties for prospective stent applications

NASA Astrophysics Data System (ADS)

Lin, Jixing; Ozan, Sertan; Li, Yuncang; Ping, Dehai; Tong, Xian; Li, Guangyu; Wen, Cuie

2016-11-01

Titanium alloys are receiving increasing research interest for the development of metallic stent materials due to their excellent biocompatibility, corrosion resistance, non-magnetism and radiopacity. In this study, a new series of Ti-Ta-Hf-Zr (TTHZ) alloys including Ti-37Ta-26Hf-13Zr, Ti-40Ta-22Hf-11.7Zr and Ti-45Ta-18.4Hf-10Zr (wt.%) were designed using the d-electron theory combined with electron to atom ratio (e/a) and molybdenum equivalence (Moeq) approaches. The microstructure of the TTHZ alloys were investigated using optical microscopy, XRD, SEM and TEM and the mechanical properties were tested using a Vickers micro-indenter, compression and tensile testing machines. The cytocompatibility of the alloys was assessed using osteoblast-like cells in vitro. The as-cast TTHZ alloys consisted of primarily β and ω nanoparticles and their tensile strength, yield strength, Young’s modulus and elastic admissible strain were measured as being between 1000.7-1172.8 MPa, 1000.7-1132.2 MPa, 71.7-79.1 GPa and 1.32-1.58%, respectively. The compressive yield strength of the as-cast alloys ranged from 1137.0 to 1158.0 MPa. The TTHZ alloys exhibited excellent cytocompatibility as indicated by their high cell viability ratios, which were close to that of CP-Ti. The TTHZ alloys can be anticipated to be promising metallic stent materials by virtue of the unique combination of extraordinarily high elastic admissible strain, high mechanical strength and excellent biocompatibility.

Novel Ti-Ta-Hf-Zr alloys with promising mechanical properties for prospective stent applications

PubMed Central

Lin, Jixing; Ozan, Sertan; Li, Yuncang; Ping, Dehai; Tong, Xian; Li, Guangyu; Wen, Cuie

2016-01-01

Titanium alloys are receiving increasing research interest for the development of metallic stent materials due to their excellent biocompatibility, corrosion resistance, non-magnetism and radiopacity. In this study, a new series of Ti-Ta-Hf-Zr (TTHZ) alloys including Ti-37Ta-26Hf-13Zr, Ti-40Ta-22Hf-11.7Zr and Ti-45Ta-18.4Hf-10Zr (wt.%) were designed using the d-electron theory combined with electron to atom ratio (e/a) and molybdenum equivalence (Moeq) approaches. The microstructure of the TTHZ alloys were investigated using optical microscopy, XRD, SEM and TEM and the mechanical properties were tested using a Vickers micro-indenter, compression and tensile testing machines. The cytocompatibility of the alloys was assessed using osteoblast-like cells in vitro. The as-cast TTHZ alloys consisted of primarily β and ω nanoparticles and their tensile strength, yield strength, Young’s modulus and elastic admissible strain were measured as being between 1000.7–1172.8 MPa, 1000.7–1132.2 MPa, 71.7–79.1 GPa and 1.32–1.58%, respectively. The compressive yield strength of the as-cast alloys ranged from 1137.0 to 1158.0 MPa. The TTHZ alloys exhibited excellent cytocompatibility as indicated by their high cell viability ratios, which were close to that of CP-Ti. The TTHZ alloys can be anticipated to be promising metallic stent materials by virtue of the unique combination of extraordinarily high elastic admissible strain, high mechanical strength and excellent biocompatibility. PMID:27897215

Synthesis and structure of U(VI), Np(VI), and Pu(VI) propionates

NASA Astrophysics Data System (ADS)

Serezhkin, V. N.; Grigor'ev, M. S.; Abdul'myanov, A. R.; Fedoseev, A. M.; Serezhkina, L. B.

2015-11-01

Crystals of [ AnO2(C2H5COO)2(H2O)2], where An = U (I), Np (II), or Pu (III), have been synthesized and studied by X-ray diffraction at 100 K. Compounds I-III are isostructural and crystallize in the monoclinic system, sp. gr. C2/ c, Z = 4, with the following unit-cell parameters: a = 7.4677(2), 7.4740(1), 7.512(2) Å, b = 14.2384(4), 14.1681(3), 14.182(4) Å, c = 10.5977(3), 10.5875(2), 10.607(3) Å, β = 92.384(1)°, 92.476(1)°, 92.668(17)°. Crystals I-III are composed of the mononuclear complexes [ AnO2(C2H5COO)2(H2O)2] as the main structural units belonging to the crystal-chemical group AB 01 2 M 1 2 ( A= AnO2+ 2, B 01 = C2H5COO-, M 1 = H2O). The crystal-chemical analysis of the structures of compounds of the composition UO2 L 2 · nH2O, where L is the carboxylate ion, is performed.

Solid state reactions of CeO 2, PuO 2, (U,Ce)O 2 and (U,Pu)O 2 with K 2S 2O 8

NASA Astrophysics Data System (ADS)

Keskar, Meera; Kasar, U. M.; Mudher, K. D. Singh; Venugopal, V.

2004-09-01

Solid state reactions of CeO 2, PuO 2 and mixed oxides (U,Ce)O 2 and (U,Pu)O 2 containing different mol.% of Ce and Pu, were carried out with K 2S 2O 8 at different temperatures to identify the formation of various products and to investigate their dissolution behaviour. X-ray, chemical and thermal analysis methods were used to characterise the products formed at various temperatures. The products obtained by heating two moles of K 2S 2O 8 with one mole each of CeO 2, PuO 2, (U,Ce)O 2 and (U,Pu)O 2 at 400 °C were identified as K 4Ce(SO 4) 4, K 4Pu(SO 4) 4, K 4(U,Ce)(SO 4) 4 and K 4(U,Pu)(SO 4) 4, respectively. K 4Ce(SO 4) 4 further decomposed to form K 4Ce(SO 4) 3.5 at 600 °C and mixture of K 2SO 4 and CeO 2 at 950 °C. Thus the products formed during the reaction of 2K 2S 2O 8 + CeO 2 show that cerium undergoes changes in oxidation state from +4 to +3 and again to +4. XRD data of K 4Ce(SO 4) 4 and K 4Ce(SO 4) 3.5 were indexed on triclinic and monoclinic system, respectively. PuO 2 + 2K 2S 2O 8 reacts at 400 °C to form K 4Pu(SO 4) 4 which was stable upto 750 °C and further decomposes to form K 2SO 4 + PuO 2 at 1000 °C. The products formed at 400 °C during the reactions of the oxides and mixed oxides were found to be readily soluble in 1-2 M HNO 3.

Vacuum Brazing TC4 Titanium Alloy to 304 Stainless Steel with Cu-Ti-Ni-Zr-V Amorphous Alloy Foil

NASA Astrophysics Data System (ADS)

Dong, Honggang; Yang, Zhonglin; Wang, Zengrui; Deng, Dewei; Dong, Chuang

2014-10-01

Dissimilar metal vacuum brazing between TC4 titanium alloy and 304 stainless steel was conducted with newly designed Cu-Ti-Ni-Zr-V amorphous alloy foils as filler metals. Solid joints were obtained due to excellent compatibility between the filler metal and stainless steel substrate. Partial dissolution of stainless steel substrate occurred during brazing. The shear strength of the joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil was 105 MPa and that with Cu37.5Ti25Ni12.5Zr12.5V12.5 was 116 MPa. All the joints fractured through the gray layer in the brazed seam, revealing brittle fracture features. Cr4Ti, Cu0.8FeTi, Fe8TiZr3 and Al2NiTi3C compounds were found in the fractured joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil, and Fe2Ti, TiCu, Fe8TiZr3 and NiTi0.8Zr0.3 compounds were detected in the joint brazed with Cu37.5Ti25Ni12.5Zr12.5V12.5 foil. The existence of Cr-Ti, Fe-Ti, Cu-Fe-Ti, and Fe-Ti-V intermetallic compounds in the brazed seam caused fracture of the resultant joints.

Long range ordered alloys modified by group IV-B metals

DOEpatents

Liu, Chain T.; Inouye, Henry; Schaffhauser, Anthony C.

1983-01-01

Ductile long range ordered alloys having high critical ordering temperatures exist in the (V,M)(Fe,Ni,Co).sub.3 system having the composition comprising by weight 20.6%-22.6% V, 14-50% Fe, 0-64% Co, and 0-40% Ni, and 0.4-1.4% M, where M is a metal selected from the group consisting of Ti, Zr, Hf, and their mixtures. These modified alloys have an electron density no greater than 8.00 and exhibit marked increases at elevated temperature in ductility and other mechanical properties over previously known ordered alloys.

Concordant 241Pu-241Am Dating of Environmental Samples: Results from Forest Fire Ash

NASA Astrophysics Data System (ADS)

Goldstein, S. J.; Oldham, W. J.; Murrell, M. T.; Katzman, D.

2010-12-01

We have measured the Pu, 237Np, 241Am, and 151Sm isotopic systematics for a set of forest fire ash samples from various locations in the western U.S. including Montana, Wyoming, Idaho, and New Mexico. The goal of this study is to develop a concordant 241Pu (t1/2 = 14.4 y)-241Am dating method for environmental collections. Environmental samples often contain mixtures of components including global fallout. There are a number of approaches for subtracting the global fallout component for such samples. One approach is to use 242Pu/239Pu as a normalizing isotope ratio in a three-isotope plot, where this ratio for the non-global fallout component can be estimated or assumed to be small. This study investigates a new, complementary method of normalization using the long-lived fission product, 151Sm (t1/2 = 90 y). We find that forest fire ash concentrates actinides and fission products with ~1E10 atoms 239Pu/g and ~1E8 atoms 151Sm/g, allowing us to measure these nuclides by mass spectrometric (MIC-TIMS) and radiometric (liquid scintillation counting) methods. The forest fire ash samples are characterized by a western U.S. regional isotopic signature representing varying mixtures of global fallout with a local component from atmospheric testing of nuclear weapons at the Nevada Test Site (NTS). Our results also show that 151Sm is well correlated with the Pu nuclides in the forest fire ash, suggesting that these nuclides have similar geochemical behavior in the environment. Results of this correlation indicate that the 151Sm/239Pu atom ratio for global fallout is ~0.164, in agreement with an independent estimate of 0.165 based on 137Cs fission yields for atmospheric weapons tests at the NTS. 241Pu-241Am dating of the non-global fallout component in the forest fire ash samples yield ages in the late 1950’s-early 1960’s, consistent with a peak in NTS weapons testing at that time. The age results for this component are in agreement using both 242Pu and 151Sm normalizations

Biotic and abiotic reduction and solubilization of Pu(IV)O₂•xH₂O(am) as affected by anthraquinone-2,6-disulfonate (AQDS) and ethylenediaminetetraacetate (EDTA).

PubMed

Plymale, Andrew E; Bailey, Vanessa L; Fredrickson, James K; Heald, Steve M; Buck, Edgar C; Shi, Liang; Wang, Zheming; Resch, Charles T; Moore, Dean A; Bolton, Harvey

2012-02-21

This study measured reductive solubilization of plutonium(IV) hydrous oxide (Pu(IV)O(2)·xH(2)O((am))) with hydrogen (H(2)) as electron donor, in the presence or absence of dissimilatory metal-reducing bacteria (DMRB), anthraquinone-2,6-disulfonate (AQDS), and ethylenediaminetetraacetate (EDTA). In PIPES buffer at pH 7 with excess H(2), Shewanella oneidensis and Geobacter sulfurreducens both solubilized <0.001% of 0.5 mM Pu(IV)O(2)·xH(2)O((am)) over 8 days, with or without AQDS. However, Pu((aq)) increased by an order of magnitude in some treatments, and increases in solubility were associated with production of Pu(III)((aq)). The solid phase of these treatments contained Pu(III)(OH)(3(am)), with more in the DMRB treatments compared with abiotic controls. In the presence of EDTA and AQDS, PuO(2)·xH(2)O((am)) was completely solubilized by S. oneidensis and G. sulfurreducens in ∼24 h. Without AQDS, bioreductive solubilization was slower (∼22 days) and less extensive (∼83-94%). In the absence of DMRB, EDTA facilitated reductive solubilization of 89% (without AQDS) to 98% (with AQDS) of the added PuO(2)·xH(2)O((am)) over 418 days. An in vitro assay demonstrated electron transfer to PuO(2)·xH(2)O((am)) from the S. oneidensis outer-membrane c-type cytochrome MtrC. Our results (1) suggest that PuO(2)·xH(2)O((am)) reductive solubilization may be important in reducing environments, especially in the presence of complexing ligands and electron shuttles, (2) highlight the environmental importance of polynuclear, colloidal Pu, (3) provide additional evidence that Pu(III)-EDTA is a more likely mobile form of Pu than Pu(IV)-EDTA, and (4) provide another example of outer-membrane cytochromes and electron-shuttling compounds facilitating bioreduction of insoluble electron acceptors in geologic environments.

Development of a new casting method to fabricate U–Zr alloy containing minor actinides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jong Hwan Kim; Hoon Song; Hyung Tae Kim

2014-01-01

Metal fuel slugs of U–Zr alloys for a sodium-cooled fast reactor (SFR) have conventionally been fabricated using an injection casting method. However, casting alloys containing volatile radioactive constituents, such as Am, are problematic in a conventional injection casting method. As an alternative fabrication method, low pressure gravity casting has been developed. Casting soundness, microstructural characteristics, alloying composition, density, and fuel losses were evaluated for the following as-cast fuel slugs: U–10 wt% Zr, U–10 wt% Zr–5 wt% RE, and U–10 wt% Zr–5 wt% RE–5 wt% Mn. The U and Zr contents were uniform throughout the matrix, and impurities such as oxyen,more » carbon, and nitrogen satisfied the specification of total impurities less than 2,000 ppm. The appearance of the fuel slugs was generally sound, and the internal integrity was shown to be satisfactory based on gamma-ray radiography. In a volatile surrogate casting test, the U–Zr–RE–Mn fuel slug showed that nearly all of the manganese was retained when casting was done under an inert atmosphere.« less

(abstract) Undercooling Studies of the Bulk Metallic Glass Forming Zr(sub 41.2)Ti(sub 13.8)Cu(sub 12.5)Ni(sub 10.0)Be(sub 22.5) Alloy During Containerless Electrostatic Levitation Processing

NASA Technical Reports Server (NTRS)

Kim, Y. J.; Busch, R.; Johnson, W. L.; Rulison, A. J.; Rhim, W. K.

1995-01-01

Bulk glass forming metallic alloys have long been desired for technological applications and for investigation into liquid undercooling, solidification processes, and thermophysical properties. A glass forming alloy Zr(sub 41.2)Ti(sub 13.8)Cu(sub 12.5)Ni(sub 10.0)Be(sub 22.5) was used to investigate the thermal treatments affecting undercooling and vitrification. The experiments were performed using the high temperature high vacuum electrostatic levitator at JPL. A sample approximately 3 mm in diameter was melted, superheated, undercooled, and solidified while levitated in high vacuum. The results show that when the sample was held above its melting temperature for a sufficient period of time to dissolve oxides and then cooled faster than a critical cooling rate, it undercooled to the glass transition temperature, T(sub g), and formed a glassy alloy. The required critical cooling rate for metallic glass formation was obtained to be between 0.9 K per second and 1.2 K per second for the 42.4 mg sample.

Hydrogen absorption of Pd/ZrO2 composites prepared from Zr65Pd35 and Zr60Pd35Pt5 amorphous alloys

NASA Astrophysics Data System (ADS)

Ozawa, Masakuni; Katsuragawa, Naoya; Hattori, Masatomo; Yogo, Toshinobu; Yamamura, Shin-ichi

2018-01-01

Metal-dispersed composites were derived from amorphous Zr65Pd35 and Zr65Pd30Pt5 alloys and their hydrogen absorption behavior was studied. X-ray diffractograms and scanning electron micrographs indicated that mixtures containing ZrO2, the metallic phase of Pd, and PdO were formed for both amorphous alloys heat-treated in air. In the composites, micron-sized Pd-based metal precipitates were embedded in a ZrO2 matrix after heat treatment at 800 °C in air. The hydrogen temperature-programmed reduction was applied to study the reactivity of hydrogen gas with the oxidized Zr65Pd35 and Zr65Pd30Pt5 materials. Rapid hydrogen absorption and release were observed on the composite derived from the amorphous alloy below 100 °C. The hydrogen pressure-concentration isotherm showed that the absorbed amount of hydrogen in materials depended on the formation of the Pd or Pt-doped Pd phase and its large interface area to the matrix in the nanocomposites. The results indicate the importance of the composite structure for the fabrication of a new type of hydrogen storage material prepared from amorphous alloys.

Investigations of systems ThO 2-MO 2-P 2O 5 (M=U, Ce, Zr, Pu). Solid solutions of thorium-uranium (IV) and thorium-plutonium (IV) phosphate-diphosphates

NASA Astrophysics Data System (ADS)

Dacheux, N.; Podor, R.; Brandel, V.; Genet, M.

1998-02-01

In the framework of nuclear waste management aiming at the research of a storage matrix, the chemistry of thorium phosphates has been completely re-examined. In the ThO 2-P 2O 5 system a new compound thorium phosphate-diphosphate Th 4(PO 4) 4P 2O 7 has been synthesized. The replacement of Th 4+ by a smaller cation like U 4+ and Pu 4+ in the thorium phosphate-diphosphate (TPD) lattice has been achieved. Th 4- xU x(PO 4) 4P 2O 7 and Th 4- xPu x(PO 4) 4P 2O 7 solid solutions have been synthesized through wet and dry processes with 0< x<3.0 for uranium and 0< x<1.0 for plutonium. From the variation of the unit cell parameters, an upper x value equal to 1.67 has been estimated for the thorium-plutonium (IV) phosphate-diphosphate solid solutions. Two other tetravalent cations, Ce 4+ and Zr 4+, cannot be incorporated in the TPD lattice: cerium (IV) because of its reduction into Ce (III) at high temperature, and zirconium probably because of its too small radius compared to thorium.

Rapid fusion method for the determination of Pu, Np, and Am in large soil samples

DOE PAGES

Maxwell, Sherrod L.; Culligan, Brian; Hutchison, Jay B.; ...

2015-02-14

A new rapid sodium hydroxide fusion method for the preparation of 10-20 g soil samples has been developed by the Savannah River National Laboratory (SRNL). The method enables lower detection limits for plutonium, neptunium, and americium in environmental soil samples. The method also significantly reduces sample processing time and acid fume generation compared to traditional soil digestion techniques using hydrofluoric acid. Ten gram soil aliquots can be ashed and fused using the new method in 1-2 hours, completely dissolving samples, including refractory particles. Pu, Np and Am are separated using stacked 2mL cartridges of TEVA and DGA Resin and measuredmore » using alpha spectrometry. The method can be adapted for measurement by inductively-coupled plasma mass spectrometry (ICP-MS). Two 10 g soil aliquots of fused soil may be combined prior to chromatographic separations to further improve detection limits. Total sample preparation time, including chromatographic separations and alpha spectrometry source preparation, is less than 8 hours.« less

Experimental Investigations into U/TRU Recovery using a Liquid Cadmium Cathode and Salt Containing High Rare Earth Concentrations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shelly X. Li; Steven D. Herrmann; Michael F. Simpson

2009-09-01

Experimental Investigations into U/TRU Recovery using a Liquid Cadmium Cathode and Salt Containing High Rare Earth Concentrations Shelly X. Li, Steven D. Herrmann, and Michael F. Simpson Pyroprocessing Technology Department Idaho National Laboratory P.O. Box 1625, Idaho Falls, ID 83415 USA Abstract - A series of six bench-scale liquid cadmium cathode (LCC) tests was performed to obtain basic separation data with focus on the behavior of rare earth elements. The electrolyte used for the tests was a mixed salt from the Mk-IV and Mk-V electrorefiners, in which spent metal fuels from Experimental Breeder Reactor-II (EBR-II) had been processed. Rare earthmore » (RE) chlorides, such as NdCl3, CeCl3, LaCl3, PrCl3, SmCl3, and YCl3, were spiked into the salt prior to the first test to create an extreme case for investigating rare earth contamination of the actinides collected by a LCC. For the first two LCC tests, an alloy with the nominal composition of 41U-30Pu-5Am-3Np-20Zr-1RE was loaded into the anode baskets as the feed material. The anode feed material for Runs 3 to 6 was spent ternary fuel (U-19Pu-10Zr). The Pu/U ratio in the salt varied from 0.6 to 1.3. Chemical and radiochemical analytical results confirmed that U and transuranics can be collected into the LCC as a group under the given run conditions. The RE contamination level in the LCC product was up to 6.7 wt% of the total metal collected. The detailed data for partitioning of actinides and REs in the salt and Cd phases are reported in the paper.« less

Atomistic modeling of high temperature uranium-zirconium alloy structure and thermodynamics

NASA Astrophysics Data System (ADS)

Moore, A. P.; Beeler, B.; Deo, C.; Baskes, M. I.; Okuniewski, M. A.

2015-12-01

A semi-empirical Modified Embedded Atom Method (MEAM) potential is developed for application to the high temperature body-centered-cubic uranium-zirconium alloy (γ-U-Zr) phase and employed with molecular dynamics (MD) simulations to investigate the high temperature thermo-physical properties of U-Zr alloys. Uranium-rich U-Zr alloys (e.g. U-10Zr) have been tested and qualified for use as metallic nuclear fuel in U.S. fast reactors such as the Integral Fast Reactor and the Experimental Breeder Reactors, and are a common sub-system of ternary metallic alloys like U-Pu-Zr and U-Zr-Nb. The potential was constructed to ensure that basic properties (e.g., elastic constants, bulk modulus, and formation energies) were in agreement with first principles calculations and experimental results. After which, slight adjustments were made to the potential to fit the known thermal properties and thermodynamics of the system. The potentials successfully reproduce the experimental melting point, enthalpy of fusion, volume change upon melting, thermal expansion, and the heat capacity of pure U and Zr. Simulations of the U-Zr system are found to be in good agreement with experimental thermal expansion values, Vegard's law for the lattice constants, and the experimental enthalpy of mixing. This is the first simulation to reproduce the experimental thermodynamics of the high temperature γ-U-Zr metallic alloy system. The MEAM potential is then used to explore thermodynamics properties of the high temperature U-Zr system including the constant volume heat capacity, isothermal compressibility, adiabatic index, and the Grüneisen parameters.

Biotic and Abiotic Reduction and Solubilization of Pu(IV)O2•xH2O(am) as Affected by Anthraquinone-2,6-disulfonate (AQDS) and Ethylenediaminetetraacetate (EDTA)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Plymale, Andrew E.; Bailey, Vanessa L.; Fredrickson, Jim K.

2012-01-24

In the presence of hydrogen (H{sub 2}), the synthetic chelating agent ethylenediaminetetraacetate (EDTA), and the electron shuttle anthraquinone-2,6-disulfonate (AQDS), the dissimilatory metal-reducing bacteria (DMRB) Shewanella oneidensis and Geobacter sulfurreducens both reductively solubilized 100% of added 0.5 mM plutonium (IV) hydrous oxide (Pu(IV)O{sub 2} {lg_bullet} xH{sub 2}O{sub (am)}) in {approx}24 h at pH 7 in a non-complexing buffer. In the absence of AQDS, bioreduction was much slower ({approx}22 days) and less extensive ({approx}83-94%). In the absence of DMRB but under comparable conditions, 89% (without AQDS) to 98% (with AQDS) of added 0.5 mM PuO{sub 2} {lg_bullet} xH{sub 2}O{sub (am)} was reductivelymore » solubilized over 418 days. Under comparable conditions but in the absence of EDTA, <0.001% of the 0.5 mM PuO{sub 2} {lg_bullet} xH{sub 2}O{sub (am)} was solubilized, with or without bacteria. However, Pu(aq) increased by as much as an order of magnitude in some EDTA-free treatments, both biotic and abiotic, and increases in solubility were associated with the production of both Pu(OH)3(am) and Pu(III)(aq). Incubation with DMRB in the absence of EDTA increased the polymeric and crystalline content of the PuO{sub 2} {lg_bullet} xH{sub 2}O{sub (am)} and also decreased Pu solubility in 6-N HCl. Results from an in vitro assay demonstrated electron transfer to PuO{sub 2} {lg_bullet} xH{sub 2}O{sub (am)} from the S. oneidensis outer-membrane c-type cytochrome MtrC, and EDTA increased the oxidation of MtrC by PuO{sub 2} {lg_bullet} xH{sub 2}O{sub (am)}. Our results suggest that PuO{sub 2} {lg_bullet} xH{sub 2}O{sub (am)} biotic and abiotic reduction and solubilization may be important in anoxic, reducing environments, especially where complexing ligands and electron shuttling compounds are present.« less

Investigation of americium-241 metal alloys for target applications. [Alloys with cerium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conner, W.V.

1980-01-01

Several americium-241 metal alloys have been investigated for possible use in the Lawrence Livermore National Laboratory Radiochemical Diagnostic Tracer Program. Alloys investigated have included uranium-americium, aluminum-americium, and cerium-americium. Uranium-americium alloys with the desired properties proved to be difficult to prepare, and work with this alloy was discontinued. Aluminum-americium alloys were much easier to prepare, but the alloy consisted of an aluminum-americium intermetallic compound (AmAl/sub 4/) in an aluminum matrix. This alloy could be cast and formed into shapes, but the low density of aluminum, and other problems; made the alloy unsuitable for the intended application. Americium metal was found tomore » have a high solid solubility in cerium and alloys prepared from these two elements exhibited all of the properties desired for the tracer program application. Cerium-americium alloys containing up to 34 wt % americium have been prepared using both comelting and coreduction techniques. The latter technique involves coreduction of Ce F/sub 4/ and AmF/sub 4/ with calcium metal in a sealed reduction vessel. Casting techniques have been developed for preparing up to eight 0.87 inch (2.2 cm) diameter disks in a single casting, and cerium-americium metal alloy disks containing from 10 to 25 wt % americium-241 have been prepared using these techniques.« less

Production and investigation of thin films of metal actinides (Pu, Am, Cm, Bk, Cf)

NASA Astrophysics Data System (ADS)

Radchenko, V. M.; Ryabinin, M. A.; Stupin, V. A.

2010-03-01

Under limited availability of transplutonium metals some special techniques and methods of their production have been developed that combine the process of metal reduction from a chemical compound and preparation of a sample for examination. In this situation the evaporation and condensation of metal onto a substrate becomes the only possible technology. Thin film samples of metallic 244Cm, 248Cm and 249Bk were produced by thermal reduction of oxides with thorium followed by deposition of the metals in the form of thin layers on tantalum substrates. For the production of 249Cf metal in the form of a thin layer the method of thermal reduction of oxide with lanthanum was used. 238Pu and 239Pu samples in the form of films were prepared by direct high temperature evaporation and condensation of the metal onto a substrate. For the production of 241Am films a gram sample of plutonium-241 metal was used containing about 18 % of americium at the time of production. Thermal decomposition of Pt5Am intermetallics in vacuum was used to produce americium metal with about 80% yield. Resistivity of the metallic 249Cf film samples was found to decrease exponentially with increasing temperature. The 249Cf metal demonstrated a tendency to form preferably a DHCP structure with the sample mass increasing. An effect of high specific activity on the crystal structure of 238Pu nuclide thin layers was studied either.

Specific features of the atomic structure of metallic layers of multilayered (CoFeZr/SiO2)32 and (CoFeZr/ a-Si)40 nanostructures with different interlayers

NASA Astrophysics Data System (ADS)

Domashevskaya, E. P.; Guda, A. A.; Chernyshev, A. V.; Sitnikov, V. G.

2017-02-01

Multilayered nanostructures (MN) were prepared by ion-beam successive sputtering from two targets, one of which was a metallic Co45Fe45Zr10 alloy plate and another target was a quartz (SiO2) or silicon plate on the surface of a rotating glass-ceramic substrate in an argon atmosphere. The Co and Fe K edges X-ray absorption fine structure of XANES in the (CoFeZr/SiO2)32 sample with oxide interlayers was similar to XANES of metallic Fe foil. This indicated the existence in metallic layers of multilayered CoFeZr nanocrystals with a local environment similar to the atomic environment in solid solutions on the base of bcc Fe structure, which is also confirmed by XRD data. XANES near the Co and Fe K edges absorption in another multilayered nanostructure with silicon interlayers (CoFeZr/ a-Si)40 differs from XANES of MN with dielectric SiO2 interlayer, which demonstrates a dominant influence of the Fe-Si and Co-Si bonds in the local environment of 3 d Co and Fe metals when they form CoFeSi-type silicide phases in thinner bilayers of this MN.

Oxidation of U-20 at% Zr alloy in air at 423 1063 K

NASA Astrophysics Data System (ADS)

Matsui, Tsuneo; Yamada, Takanobu; Ikai, Yasushi; Naito, Keiji

1993-01-01

The oxidation behavior of U 0.80Zr 0.20 alloy (two-phase mixture of U and UZr 2 below 878 K and single solid solution above 1008 K) was studied by thermogravimetry in the temperature range from 423 to 1063 K in air. During oxidation in the low temperature region (423-503 K), the sample kept its initial shape (a rectangular rod) and the surface of the sample was covered by a black thin adherent UO2 + x oxide layer. On the other hand, by oxidation in the middle temperature region, the sample broke to several pieces of thin plates and blocks, and fine powder at 643-723 K and entirely to fine powder at 775-878 K, all of which were analyzed to be a mixture of U 3O 8 and ZrO 2. By oxidation in the high temperature region (1008-1063 K) the sample broke to very fine powder, which consisted of U 3O 8 and ZrO 2. Based on the sample shape, the oxide phase identified after oxidation and the slope value of the bilogarithmic plots of the weight gain against time, the oxidation kinetics was analyzed with a paralinear equation in the low temperature region below 503 K and a linear equation in the middle and high temperature regions above 643 K. Oxidation rates of U 0.80Zr 0.20 (two-phase mixture) in the low and middle temperature regions were smaller than those of uranium metal. A discontinuity in the plot of the linear oxidation rate constant versus reciprocal temperature was found to be present between 723 and 838 K, similarly to the case of uranium metal previously reported. The linear rate constants of single-phase solid solution in the high temperature region above 1008 K seemed to be a little smaller than those estimated by the extrapolation of the values in the middle temperature region.

Radiochemical determination of 237NP in soil samples contaminated with weapon grade plutonium

NASA Astrophysics Data System (ADS)

Antón, M. P.; Espinosa, A.; Aragón, A.

2006-01-01

The Palomares terrestrial ecosystem (Spain) constitutes a natural laboratory to study transuranics. This scenario is partially contaminated with weapon-grade plutonium since the burnout and fragmentation of two thermonuclear bombs accidentally dropped in 1966. While performing radiometric measurements in the field, the possible presence of 237Np was observed through its 29 keV gamma emission. To accomplish a detailed characterization of the source term in the contaminated area using the isotopic ratios Pu-Am-Np, the radiochemical isolation and quantification by alpha spectrometry of 237Np was initiated. The selected radiochemical procedure involves separation of Np from Am, U and Pu with ionic resins, given that in soil samples from Palomares 239+240Pu levels are several orders of magnitude higher than 237Np. Then neptunium is isolated using TEVA organic resins. After electrodeposition, quantification is performed by alpha spectrometry. Different tests were done with blank solutions spiked with 236Pu and 237Np, solutions resulting from the total dissolution of radioactive particles and soil samples. Results indicate that the optimal sequential radionuclide separation order is Pu-Np, with decontamination percentages obtained with the ionic resins ranging from 98% to 100%. Also, the addition of NaNO2 has proved to be necessary, acting as a stabilizer of Pu-Np valences.

The influence of Zr substitution for Nb on the corrosion behaviors of the Ni-Nb-Zr bulk metallic glasses

NASA Astrophysics Data System (ADS)

Li, DengKe; Zhu, ZhengWang; Zhang, HaiFeng; Wang, AiMin; Hu, ZhuangQi

2012-12-01

The influence of Zr content on corrosion behaviors of the Ni61.5Nb38.5- x Zr x ( x=1, 3, 5, 7, 9 at.%) bulk metallic glasses (BMGs) in 1 M HCl aqueous solution was investigated by potentiodynamic polarization measurements and X-ray photo-electron spectroscopy (XPS). It was found that these BMG alloys possess superior corrosion resistance, that is, with large passive region of about 1.5 V and low passive current density (as low as 0.05 Am-2 for Ni61.5Nb31.5Zr7). XPS analysis indicates that the high corrosion resistance is attributed to the formation of Nb- and Zr-enriched surface films formed in the aggressive acid solution. The Zr substitution for Nb effectively reduces the Ni content, particularly the metallic state Ni content in the surface films, which depresses the electrical conduction of the surface films and reduces the passive current density, thus leading to the enhancement of the corrosion resistance of these Ni-Nb-Zr BMGs. These alloys may potentially be useful for engineering applications.

Impact of the cation distribution homogeneity on the americium oxidation state in the U0.54Pu0.45Am0.01O2-x mixed oxide

NASA Astrophysics Data System (ADS)

Vauchy, Romain; Robisson, Anne-Charlotte; Martin, Philippe M.; Belin, Renaud C.; Aufore, Laurence; Scheinost, Andreas C.; Hodaj, Fiqiri

2015-01-01

The impact of the cation distribution homogeneity of the U0.54Pu0.45Am0.01O2-x mixed oxide on the americium oxidation state was studied by coupling X-ray diffraction (XRD), electron probe micro analysis (EPMA) and X-ray absorption spectroscopy (XAS). Oxygen-hypostoichiometric Am-bearing uranium-plutonium mixed oxide pellets were fabricated by two different co-milling based processes in order to obtain different cation distribution homogeneities. The americium was generated from β- decay of 241Pu. The XRD analysis of the obtained compounds did not reveal any structural difference between the samples. EPMA, however, revealed a high homogeneity in the cation distribution for one sample, and substantial heterogeneity of the U-Pu (so Am) distribution for the other. The difference in cation distribution was linked to a difference in Am chemistry as investigated by XAS, with Am being present at mixed +III/+IV oxidation state in the heterogeneous compound, whereas only Am(IV) was observed in the homogeneous compound. Previously reported discrepancies on Am oxidation states can hence be explained by cation distribution homogeneity effects.

Corrosion behavior in high-temperature pressurized water of Zircaloy-4 joints brazed with Zr-Cu-based amorphous filler alloys

NASA Astrophysics Data System (ADS)

Lee, Jung Gu; Lee, Gyoung-Ja; Park, Jin-Ju; Lee, Min-Ku

2017-05-01

The compositional effects of ternary Zr-Cu-X (X: Al, Fe) amorphous filler alloys on galvanic corrosion susceptibility in high-temperature pressurized water were investigated for Zircaloy-4 brazed joints. Through an Al-induced microgalvanic reaction that deteriorated the overall nobility of the joint, application of the Zr-Cu-Al filler alloy caused galvanic coupling to develop readily between the Al-bearing joint and the Al-free base metal, finally leading to massive localized corrosion of the joint. Contrastingly, joints prepared with a Zr-Cu-Fe filler alloy showed excellent corrosion resistance comparable to that of the Zircaloy-4 base metal, since the Cu and Fe elements forming fine intermetallic particles with Zr did not influence the electrochemical stability of the resultant joints. The present results demonstrate that Fe is a more suitable alloying element than Al for brazing filler alloys subjected to high-temperature corrosive environments.

High pressure study of Pu(0.92)Am(0.08) binary alloy.

PubMed

Klosek, V; Griveau, J C; Faure, P; Genestier, C; Baclet, N; Wastin, F

2008-07-09

The phase transitions (by means of x-ray diffraction) and electrical resistivity of a Pu(0.92)Am(0.08) binary alloy were determined under pressure (up to 2 GPa). The evolution of atomic volume with pressure gives detailed information concerning the degree of localization of 5f electronic states and their delocalization process. A quasi-linear V = f(P) dependence reflects subtle modifications of the electronic structure when P increases. The electrical resistivity measurements reveal the very high stability of the δ phase for pressures less than 0.7 GPa, since no martensitic-like transformation occurs at low temperature. Remarkable electronic behaviours have also been observed. Finally, resistivity curves have shown the temperature dependence of the phase transformations together with unexpected kinetic effects.

Investigation of the system ThO 2-NpO 2-P 2O 5. Solid solutions of thorium-neptunium (IV) phosphate-diphosphate

NASA Astrophysics Data System (ADS)

Dacheux, N.; Thomas, A. C.; Brandel, V.; Genet, M.

1998-11-01

Considering that phosphate matrices could be potential candidates for the immobilization of actinides or for the final disposal of the excess plutonium from dismantled nuclear weapons, the chemistry of thorium phosphates has been re-examined. In the ThO 2-P 2O 5 system, the thorium phosphate-diphosphate Th 4(PO 4) 4P 2O 7 (TPD) can be synthesized by wet and dry chemical processes. The substitution of thorium by other tetravalent actinides like uranium or plutonium can be obtained for 0 < x < 3.0 and 0 < x < 1.63, respectively. In this work, we report the chemical conditions of synthesis of thorium-neptunium (IV) phosphate-diphosphate solid solutions Th 4- xNp x(PO 4) 4P 2O 7 (TNPD) with 0 < x < 1.6 from a mixture of thorium and neptunium (IV) nitrates and concentrated phosphoric acid. From the variation of the cell parameters and volume, the maximum substitution of Th 4+ by Np 4+ in the TPD structure is evaluated to 2.08 (which corresponds to about 52 mol% of thorium replaced by neptunium (IV)). The field of existence of solid solutions Th 4- xU- xNp- xPuU xUNp xNpPu xPu(PO 4)4P 2O 7 has been calculated. These solid solutions should be synthesized for 5 xU+7 xNp+9 xPu⩽15. In the NpO 2-P 2O 5 system, the unit cell parameters of Np 2O(PO 4) 2 were refined by analogy with U 2O(PO 4) 2 which crystallographic data have been published recently. For Np 2O(PO 4) 2 the unit cell is orthorhombic with the following cell parameters: a=7.033(2) Å, b=9.024(3) Å, c=12.587(6) Å and V=799(1) Å 3. The unit cell parameter obtained for α-NpP 2O 7 ( a=8.586(1) Å) is in good agreement with those already reported in literature.

Heptavalent Neptunium in a Gas-Phase Complex: (Np VIIO 3 +)(NO 3 –) 2

DOE PAGES

Dau, Phuong D.; Maurice, Remi; Renault, Eric; ...

2016-09-15

A central goal of chemistry is to achieve ultimate oxidation states, including in gas-phase complexes with no condensed phase perturbations. In the case of the actinide elements, the highest established oxidation states are labile Pu(VII) and somewhat more stable Np(VII). We have synthesized and characterized gas-phase AnO 3(NO 3) 2- complexes for An = U, Np, and Pu by endothermic NO 2 elimination from AnO 2(NO 3) 3-. It was previously demonstrated that the PuO 3+ core of PuO 3(NO 3) 2- has a Pu—O• radical bond such that the oxidation state is Pu(VI); it follows that in UO 3(NOmore » 3) 2- it is the stable U(VI) oxidation state. On the basis of the relatively more facile synthesis of NpO 3(NO 3) 2-, a Np(VII) oxidation state is inferred. This interpretation is substantiated by reactivity of the three complexes: NO 2 spontaneously adds to UO 3(NO 3) 2- and PuO 3(NO 3) 2- but not to NpO 3(NO 3) 2-. This unreactive character is attributed to a Np(VII)O 3+ core with three stable Np=O bonds, this in contrast to reactive U—O• and Pu—O• radical bonds. The computed structures and reaction energies for the three AnO 3(NO 3) 2- support the conclusion that the oxidation states are U(VI), Np(VII), and Pu(VI). These results establish the extreme Np(VII) oxidation state in a gas-phase complex, and demonstrate the inherently greater stability of Np(VII) versus Pu(VII).« less

Atomic layer deposition of ZrO2 on W for metal-insulator-metal capacitor application

NASA Astrophysics Data System (ADS)

Lee, Sang-Yun; Kim, Hyoungsub; McIntyre, Paul C.; Saraswat, Krishna C.; Byun, Jeong-Soo

2003-04-01

A metal-insulator-metal (MIM) capacitor using ZrO2 on tungsten (W) metal bottom electrode was demonstrated and characterized in this letter. Both ZrO2 and W metal were synthesized by an atomic layer deposition (ALD) method. High-quality 110˜115 Å ZrO2 films were grown uniformly on ALD W using ZrCl4 and H2O precursors at 300 °C, and polycrystalline ZrO2 in the ALD regime could be obtained. A 13˜14-Å-thick interfacial layer between ZrO2 and W was observed after fabrication, and it was identified as WOx through angle-resolved x-ray photoelectron spectroscopy analysis with wet chemical etching. The apparent equivalent oxide thickness was 20˜21 Å. An effective dielectric constant of 22˜25 including an interfacial WOx layer was obtained by measuring capacitance and thickness of MIM capacitors with Pt top electrodes. High capacitance per area (16˜17 fF/μm2) and low leakage current (10-7 A/cm2 at ±1 V) were achieved.

Reductive Dissolution of PuO2(am): The Effect of Fe(II) and Hydroquinone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rai, Dhanpat; Gorby, Yuri A.; Fredrickson, Jim K.

2002-06-01

SYNOPIS-Reducing agents commonly present in geologic environments can increase solubility of PuO2(am), which is otherwise very insoluble, by many orders of magnitude through reduction of Pu(IV) to Pu(III). The reduction reactions involving Fe(II) and hydroquinone, hitherto unquantified under environmental pH values, were found to be relatively fast and controlled the extent of PuO2(am) dissolution: a decrease in redox potential (pe + pH) resulted in concomitant increase in PuO2(am) solubility.

Full-length U-xPu-10Zr (x = 0, 8, 19 wt.%) fast reactor fuel test in FFTF

NASA Astrophysics Data System (ADS)

Porter, D. L.; Tsai, Hanchung

2012-08-01

The Integral Fast Reactor-1 (IFR-1) experiment performed in the Fast Flux Test Facility (FFTF) was the only U-Pu-10Zr (Pu-0, 8 and 19 wt.%) metallic fast reactor test with commercial-length (91.4-cm active fuel-column length) conducted to date. With few remaining test reactors, there is little opportunity for performing another test with a long active fuel column. The assembly was irradiated to the goal burnup of 10 at.%. The beginning-of-life (BOL) peak cladding temperature of the hottest pin was 608 °C, cooling to 522 °C at end-of-life (EOL). Selected fuel pins were examined non-destructively using neutron radiography, precision axial gamma scanning, and both laser and spiral contact cladding profilometry. Destructive exams included plenum gas pressure, volume, and gas composition determinations on a number of pins followed by optical metallography, electron probe microanalysis (EPMA), and alpha and beta-gamma autoradiography on a single U-19Pu-10Zr pin. The post-irradiation examinations (PIEs) showed very few differences compared to the short-pin (34.3-cm fuel column) testing performed on fuels of similar composition in Experimental Breeder Reactor-II (EBR-II). The fuel column grew axially slightly less than observed in the short pins, but with the same pattern of decreasing growth with increasing Pu content. There was a difference in the fuel-cladding chemical interaction (FCCI) in that the maximum cladding penetration by interdiffusion with fuel/fission products did not occur at the top of the fuel column where the cladding temperature is highest, as observed in EBR-II tests. Instead, the more exaggerated fission-rate profile of the FFTF pins resulted in a peak FCCI at ˜0.7 X/L axial location along the fuel column. This resulted from a higher production of rare-earth fission products at this location and a higher ΔT between fuel center and cladding than at core center, together providing more rare earths at the cladding and more FCCI. This behavior could

Upper critical fields and superconducting transition temperatures of some zirconium-base amorphous transition-metal alloys

NASA Astrophysics Data System (ADS)

Karkut, M. G.; Hake, R. R.

1983-08-01

Superconducting upper critical fields Hc2(T), transition temperatures Tc and normal-state electrical resistivities ρn have been measured in the amorphous transition-metal alloy series Zr1-xCox, Zr1-xNix, (Zr1-xTix)0.78Ni0.22, and (Zr1-xNbx)0.78Ni0.22. Structural integrity of these melt-spun alloys is indicated by x-ray, density, bend-ductility, normal-state electrical resistivity, superconducting transition width, and mixed-state flux-pinning measurements. The specimens display Tc=2.1-3.8 K, ρn=159-190 μΩ cm, and |(dHc2dT)Tc|=28-36 kG/K. These imply electron mean free paths l~2-6 Å, zero-temperature Ginzburg-Landau coherence distances ξG0~50-70 Å, penetration depths λG0~(7-10)×103 Å, and extremely high dirtiness parameters ξ0l~300-1300. All alloys display Hc2(T) curves with negative curvature and (with two exceptions) fair agreement with the standard dirty-limit theory of Werthamer, Helfand, Hohenberg, and Maki (WHHM) for physically reasonable values of spin-orbit-coupling induced, electron-spin-flip scattering time τso. This is in contrast to the anomalously elevated Hc2(T) behavior which is nearly linear in T that is observed by some, and the unphysically low-τso fits to WHHM theory obtained by others, for various amorphous alloys. Current ideas that such anomalies may be due to alloy inhomogeneity are supported by present results on two specimens for which relatively low-τso fits of Hc2(T) to WHHM theory are coupled with superconductive evidence for inhomogeneity: relatively broad transitions at Tc and Hc2 current-density-dependent transitions at Hc2 and (in one specimen) a J-dependent, high-H (>Hc2), resistive "beak effect." In the Zr1-xCox and Zr1-xNix series, Tc decreases linearly with x (and with unfilled-shell average electron-to-atom ratio < ea > in the range 5.05<=< ea ><=6.40 in fair agreement with previous results for these systems and contrary to the Tc vs < ea > behavior of both amorphous and crystalline transition-metal alloys formed

Transformation behavior of the γU(Zr,Nb) phase under continuous cooling conditions

NASA Astrophysics Data System (ADS)

Komar Varela, C. L.; Gribaudo, L. M.; González, R. O.; Aricó, S. F.

2014-10-01

The selected alloy for designing a high-density monolithic-type nuclear fuel with U-Zr-Nb alloy as meat and Zry-4 as cladding, has to remain in the γU(Zr,Nb) phase during the whole fabrication process. Therefore, it is necessary to define a range of concentrations in which the γU(Zr,Nb) phase does not decompose under the process conditions. In this work, several U alloys with concentrations between 28.2-66.9 at.% Zr and 0-13.3 at.% Nb were fabricated to study the possible transformations of the γU(Zr,Nb) phase under different continuous cooling conditions. The results of the electrical resistivity vs temperature experiments are presented. For a cooling rate of 4 °C/min a linear regression was determined by fitting the starting decomposition temperature as a function of Nb concentration. Under these conditions, a concentration of 45.3 at.% Nb would be enough to avoid any transformation of the γU(Zr,Nb) phase. In experiments that involve higher cooling conditions, it has been determined that this concentration can be halved.

Chemical potential of oxygen in (U, Pu) mixed oxide with Pu/(U+Pu) = 0.46

NASA Astrophysics Data System (ADS)

Dawar, Rimpi; Chandramouli, V.; Anthonysamy, S.

2016-05-01

Chemical potential of oxygen in (U,Pu) mixed oxide with Pu/(U + Pu) = 0.46 was measured for the first time using H2/H2O gas equilibration combined with solid electrolyte EMF technique at 1073, 1273 and 1473 K covering an oxygen potential range of -525 to -325 kJ mol-1. The effect of oxygen potential on the oxygen to metal ratio was determined. Increase in oxygen potential increases the O/M. In this study the minimum O/M obtained was 1.985 below which reduction was not possible. Partial molar enthalpy ΔHbar O2 and entropy ΔSbar O2 of oxygen were calculated from the oxygen potential data. The values of -752.36 kJ mol-1 and 0.25 kJ mol-1 were obtained for ΔHbar O2 and ΔSbar O2 respectively.

Pressure-induced positive electrical resistivity coefficient in Ni-Nb-Zr-H glassy alloy

NASA Astrophysics Data System (ADS)

Fukuhara, M.; Gangli, C.; Matsubayashi, K.; Uwatoko, Y.

2012-06-01

Measurements under hydrostatic pressure of the electrical resistivity of (Ni0.36Nb0.24Zr0.40)100-xHx (x = 9.8, 11.5, and 14) glassy alloys have been made in the range of 0-8 GPa and 0.5-300 K. The resistivity of the (Ni0.36Nb0.24Zr0.40)86H14 alloy changed its sign from negative to positive under application of 2-8 GPa in the temperature range of 300-22 K, coming from electron-phonon interaction in the cluster structure under pressure, accompanied by deformation of the clusters. In temperature region below 22 K, the resistivity showed negative thermal coefficient resistance by Debye-Waller factor contribution, and superconductivity was observed at 1.5 K.

AmO 2 Analysis for Analytical Method Testing and Assessment: Analysis Support for AmO 2 Production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuhn, Kevin John; Bland, Galey Jean; Fulwyler, James Brent

Americium oxide samples will be measured for various analytes to support AmO 2 production. The key analytes that are currently requested by the Am production customer at LANL include total Am content, Am isotopics, Pu assay, Pu isotopics, and trace element content including 237Np content. Multiple analytical methods will be utilized depending on the sensitivity, accuracy and precision needs of the Am matrix. Traceability to the National Institute of Standards and Technology (NIST) will be achieved, where applicable, by running NIST traceable quality control materials. This given that there are no suitable AmO 2 reference materials currently available for requestedmore » analytes. The primary objective is to demonstrate the suitability of actinide analytical chemistry methods to support AmO 2 production operations.« less

The influence of Sr on the microstructure, degradation and stress corrosion cracking of the Mg alloys - ZK40xSr.

PubMed

Chen, Lianxi; Bin, Yuanhong; Zou, Wenqi; Wang, Xiaojian; Li, Wei

2017-02-01

In the present work, new magnesium (Mg) alloys (Mg-4Zn-0.6Zr-xSr, x=0, 0.4, 0.8, 1.2, 1.6wt%; ZK40xSr) were prepared and studied as potential biodegradable materials. The influence of strontium (Sr) addition on the properties of the new Mg alloys was investigated, which included microstructure, corrosion degradation, and the stress corrosion cracking (SCC) susceptibility. The average grain size of the ZK40Sr was approximately 100µm, which was significantly smaller than that of ZK40 alloy without Sr (402.3±40.2µm). The size of grain boundaries precipitates in the ZK40xSr alloys gradually increased with the increase of Sr content. The grain boundaries finally showed a continuously distribution and net-like shape. The degradation test showed that the average degradation rate of the ZK40xSr alloys increased with the increase of Sr addition. In the case of Mg-4Zn-0.6Zr, the degradation rate was 2.2mgcm -2 day -1 , which was lower than that of Mg-4Zn-0.6Zr-1.6Sr (4.93mgcm -2 day -1 ). When the ZK40xSr alloys were immersed in m-SBF, the rod-like Sr-contained hydroxyapatite (HA) substance was detected, which was known to enhance cell growth around bone implants. The fracture surfaces of the as-cast Mg-4Zn-0.6Zr-1.6Sr were shown intergranular stress corrosion cracking (IGSCC) patterns. The increase of SCC susceptibility of the higher Sr ZK40xSr alloys was attributed to the increase of micro-galvanic corrosion between the α-Mg and the grain boundaries precipitates. The SCC susceptibility values were ≈0.13 and ≈0.41 for the Mg-4Zn-0.6Zr-0.4Sr and the Mg-4Zn-0.6Zr-1.6Sr, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

Oxidation/reduction studies on Zr yU 1-yO 2+x and delineation of a new orthorhombic phase in U-Zr-O system

NASA Astrophysics Data System (ADS)

Sali, S. K.; Kulkarni, N. K.; Krishnan, K.; Achary, S. N.; Tyagi, A. K.

2008-08-01

In this communication, we report the oxidation and reduction behavior of fluorite type solid solutions in U-Zr-O. The maximum solubility of ZrO 2 in UO 2 lattice could be achieved with a mild oxidizing followed by reducing conditions. The role of valency state of U is more dominating in controlling the unit cell parameters than the incorporated interstitial oxygen in the fluorite lattice. The controlled oxidation studies on U-Zr-O solid solutions led to the delineation of a new distorted fluorite lattice at the U:Zr=2:1 composition. The detailed crystal structure analysis of this ordered composition Zr 0.33U 0.67O 2.33 (ZrU 2O 7) has been carried from the powder XRD data. This phase crystallizes in an orthorhombically distorted fluorite type lattice with unit cell parameters: a=5.1678(2), b=5.4848(2), c=5.5557(2) Å and V=157.47(1) Å 3 (Space group: Cmcm, No. 63). The metal ions have distorted cubical polyhedra with anion similar to the fluorite structure. The excess anions are occupied in the interstitial (empty cubes) of the fluorite unit cell. The crystal structure and chemical analyses suggest approximately equal fractions of U 4+ and U 6+ in this compound. The details of the thermal stability as well as kinetics of formation and oxidation of ZrU 2O 7 are also studied using thermogravimetry.

Electric resistivity and thermoelectricity of Ni-Nb-Zr and Ni-Nb-Zr-H glassy alloys

NASA Astrophysics Data System (ADS)

Fukuhara, Mikio; Inoue, Akihisa

2010-09-01

Electric resistivity ρ and thermoelectric power S of Ni 36Nb 24Zr 40 and (Ni 0.36Nb 0.24Zr 0.4) 90H 10 glassy alloys were investigated in temperature region between 1.5 and 300 K. After resistivity curves of both alloys increase gradually with decreasing temperature down to around 6 K, they dropped suddenly and then reached zero resistivity at 2.1 K, leading to superconductivity. Linear curve with negative TCR of ρ vs T2 and slight increase of S/ T in temperature region down to around 6 K clearly reveal Fermi-liquid phenomenon in electronic state for both alloys independent of hydrogen content.

Examination of Multiphase (Zr,Ti)(V,Cr,Mn,Ni)2 Ni-MH Electrode Alloys: Part II. Solid-State Transformation of the Interdendritic B2 Phase

NASA Astrophysics Data System (ADS)

Bendersky, L. A.; Wang, K.; Boettinger, W. J.; Newbury, D. E.; Young, K.; Chao, B.

2010-08-01

Solidification microstructure of multicomponent (Zr,Ti)-Ni-(V,Cr,Mn,Co) alloys intended for use as negative electrodes in Ni-metal hydride (Ni-MH) batteries was studied in Part I of this series of articles. Part II of the series examines the complex internal structure of the interdendritic grains formed by solid-state transformation and believed to play an important role in the electrochemical charge/discharge characteristics of the overall alloy composition. By studying one alloy, Zr21Ti12.5V10Cr5.5Mn5.1Co5.0Ni40.2Al0.5Sn0.3, it is shown that the interdendritic grains solidify as a B2 (Ti,Zr)44(Ni,TM)56 phase, and then undergo transformation to Zr7Ni10-type, Zr9Ni11-type, and martensitic phases. The transformations obey orientation relationships between the high-temperature B2 phase and the low-temperature Zr-Ni-type intermetallics, and consequently lead to a multivariant structure. The major orientation relationship for the orthorhombic Zr7Ni10 type is [011]Zr7Ni10//[001]B2; (100)Zr7Ni10//(100)B2. The orientation relationship for the tetragonal Zr9Ni11 type is [001]Zr9Ni11//[001]B2; (130)Zr9Ni11//(100)B2. Binary Ni-Zr and ternary Ti-Ni-Zr phase diagrams were used to rationalize the formation of the observed domain structure.

The use of MOX caramel fuel mixed with 241Am, 242mAm and 243Am as burnable absorber actinides for the MTR research reactors.

PubMed

Shaaban, Ismail; Albarhoum, Mohamad

2017-07-01

The MOX (UO 2 &PuO 2 ) caramel fuel mixed with 241 Am, 242m Am and 243 Am as burnable absorber actinides was proposed as a fuel of the MTR-22MW reactor. The MCNP4C code was used to simulate the MTR-22MW reactor and estimate the criticality and the neutronic parameters, and the power peaking factors before and after replacing its original fuel (U 3 O 8 -Al) by the MOX caramel fuel mixed with 241 Am, 242m Am and 243 Am actinides. The obtained results of the criticality, the neutronic parameters, and the power peaking factors for the MOX caramel fuel mixed with 241 Am, 242m Am and 243 Am actinides were compared with the same parameters of the U 3 O 8 -Al original fuel and a maximum difference is -6.18% was found. Additionally, by recycling 2.65% and 2.71% plutonium and 241 Am, 242m Am and 243 Am actinides in the MTR-22MW reactor, the level of 235 U enrichment is reduced from 4.48% to 3% and 2.8%, respectively. This also results in the reduction of the 235 U loading by 32.75% and 37.22% for the 2.65%, the 2.71% plutonium and 241 Am, 242m Am and 243 Am actinides, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Report on the Synchrotron Characterization of U-Mo and U-Zr Alloys and the Modeling Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okuniewski, Maria A.; Ganapathy, Varsha; Hamilton, Brenden

2016-09-01

ABSTRACT Uranium-molybdenum (U-Mo) and uranium-zirconium (U-Zr) are two promising fuel candidates for nuclear transmutation reactors which burn long-lived minor actinides and fission products within fast spectrum reactors. The objectives of this research are centered on understanding the early stages of fuel performance through the examination of the irradiation induced microstructural changes in U-Zr and U-Mo alloys subjected to low neutron fluences. Specimens that were analyzed include those that were previously irradiated in the Advanced Test Reactor at INL. This most recent work has focused on a sub-set of the irradiated specimens, specifically U-Zr and U-Mo alloys that were irradiated tomore » 0.01 dpa at temperatures ranging from (150-800oC). These specimens were analyzed with two types of synchrotron techniques, including X-ray absorption fine structure and X-ray diffraction. These techniques provide non-destructive microstructural analysis, including phase identification and quantitation, lattice parameters, crystallite sizes, as well as bonding, structure, and chemistry. Preliminary research has shown changes in the phase fractions, crystallite sizes, and lattice parameters as a function of irradiation and temperature. Future data analyses will continue to explore these microstructural changes.« less

Cladding of Mg alloy with Zr based BMG Alloy

NASA Astrophysics Data System (ADS)

Prasada Rao, A. K.; Oh, Y. S.; Faisal, M. K.; Kim, N. J.

2016-02-01

In the present work, an attempt has been made to clad AZ31 magnesium alloy with Zr-based bulk metallic glassy alloy (Vit-1), by casting method. The interface studies conducted using SEM-EDS line scan indicate that a good bond is formed at the clad interface of Zr and Mg. And the mechanism involved is discussed herein.

Real-time monitoring of plutonium content in uranium-plutonium alloys

DOEpatents

Li, Shelly Xiaowei; Westphal, Brian Robert; Herrmann, Steven Douglas

2015-09-01

A method and device for the real-time, in-situ monitoring of Plutonium content in U--Pu Alloys comprising providing a crucible. The crucible has an interior non-reactive to a metallic U--Pu alloy within said interior of said crucible. The U--Pu alloy comprises metallic uranium and plutonium. The U--Pu alloy is heated to a liquid in an inert or reducing atmosphere. The heated U--Pu alloy is then cooled to a solid in an inert or reducing atmosphere. As the U--Pu alloy is cooled, the temperature of the U--Pu alloy is monitored. A solidification temperature signature is determined from the monitored temperature of the U--Pu alloy during the step of cooling. The amount of Uranium and the amount of Plutonium in the U--Pu alloy is then determined from the determined solidification temperature signature.

Microstructure, Surface Characterization, and Electrochemical Behavior of New Ti-Zr-Ta-Ag Alloy in Simulated Human Electrolyte

NASA Astrophysics Data System (ADS)

Vasilescu, Cora; Drob, Silviu Iulian; Osiceanu, Petre; Moreno, Jose Maria Calderon; Prodana, Mariana; Ionita, Daniela; Demetrescu, Ioana; Marcu, Maria; Popovici, Ion Alexandru; Vasilescu, Ecaterina

2017-01-01

A new Ti-20Zr-5Ta-2Ag alloy was elaborated and characterized regarding its microstructure, its native passive film composition and thickness, its surface wettability, its electrochemical behavior in Ringer solution of different pH values, and its ion release. The new alloy has a bi-phase, α + β, acicular, homogeneous microstructure (scanning electron microscopy (SEM)). Its native passive film (12-nm thicknesses) consists of the protective TiO2, ZrO2, and Ta2O5 oxides, Ti and Ta suboxides, and metallic Ag (X-ray photoelectron spectroscopy (XPS) data). The alloy possesses high hydrophilic properties. The main electrochemical parameters of the new alloy are superior to those of Ti as a result of the beneficial influence of Zr, Ta, and Ag alloying elements, which reinforce its native passive film. Electrochemical impedance spectroscopy (EIS) spectra in Ringer solutions for the new alloy displayed better values of impedances and phase angles, proving a more insulate passive film than that on the Ti surface. The main corrosion parameters for the new Ti-20Zr-5Ta-2Ag alloy are more favorable by about 25 to 38 times than those of Ti, confirming extremely resistant passive film. The new Ti-20Zr-5Ta-2Ag alloy releases into Ringer solution low quantities of Ti4+, Zr4+ metallic ions (inductively coupled plasma-mass spectroscopy (ICP-MS)). The Ag+ ions are released in low quantity, conferring to this alloy's low antibacterial activity. All experimental results show that the new Ti-20Zr-5Ta-2Ag alloy fulfills the requirements for biocompatibility, corrosion resistance, and antibacterial protection.

Effect of different Zr contents on properties and microstructure of Cu-Cr-Zr alloys

NASA Astrophysics Data System (ADS)

Jinshui, Chen; Bin, Yang; Junfeng, Wang; Xiangpeng, Xiao; Huiming, Chen; Hang, Wang

2018-02-01

The crystallography and morphology of precipitate particles of Cu-Cr-Zr alloys with varying Zr contents were studied by transmission electron microscopy (TEM) after solution treatments at 950 °C for 1 h and aging treatments at 500 °C for different times ranged from 0.5 h to 24 h. The microhardness and electrical conductivity of Cu-Cr-Zr alloys after various aging process were tested. The results show that the microhardness and electrical conductivity rapidly increased at first, then the microhardness decreased slowly after reaching the peak, while the conductivity continues to increase. Nano-scaled precipitates exhibit two kinds of morphology (coffee bean and ellipse shaped). With increasing Zr content, the Zr-containing precipitation sequence of Cu-Cr-Zr alloys at peak-ageing is Heusler CrCu2Zr → Cu5Zr → Cu4Zr. The Heusler CrCu2Zr phase decomposed into fine and homogeneous Cr and Cu4Zr, resulting in improved alloy properties.

Fuel Performance Experiments and Modeling: Fission Gas Bubble Nucleation and Growth in Alloy Nuclear Fuels

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDeavitt, Sean; Shao, Lin; Tsvetkov, Pavel

2014-04-07

Advanced fast reactor systems being developed under the DOE's Advanced Fuel Cycle Initiative are designed to destroy TRU isotopes generated in existing and future nuclear energy systems. Over the past 40 years, multiple experiments and demonstrations have been completed using U-Zr, U-Pu-Zr, U-Mo and other metal alloys. As a result, multiple empirical and semi-empirical relationships have been established to develop empirical performance modeling codes. Many mechanistic questions about fission as mobility, bubble coalescience, and gas release have been answered through industrial experience, research, and empirical understanding. The advent of modern computational materials science, however, opens new doors of development suchmore » that physics-based multi-scale models may be developed to enable a new generation of predictive fuel performance codes that are not limited by empiricism.« less

Surface thermodynamic stability, electronic and magnetic properties in various (001) surfaces of Zr2CoSn Heusler alloy

NASA Astrophysics Data System (ADS)

Yang, Yan; Feng, Zhong-Ying; Zhang, Jian-Min

2018-05-01

The spin-polarized first-principles are used to study the surface thermodynamic stability, electronic and magnetic properties in various (001) surfaces of Zr2CoSn Heusler alloy, and the bulk Zr2CoSn Heusler alloy are also discussed to make comparison. The conduction band minimum (CBM) of half-metallic (HM) bulk Zr2CoSn alloy is contributed by ZrA, ZrB and Co atoms, while the valence band maximum (VBM) is contributed by ZrB and Co atoms. The SnSn termination is the most stable surface with the highest spin polarizations P = 77.1% among the CoCo, ZrCo, ZrZr, ZrSn and SnSn terminations of the Zr2CoSn (001) surface. In the SnSn termination of the Zr2CoSn (001) surface, the atomic partial density of states (APDOS) of atoms in the surface, subsurface and third layers are much influenced by the surface effect and the total magnetic moment (TMM) is mainly contributed by the atomic magnetic moments of atoms in fourth to ninth layers.

{sup 237}Np in Hemp-palm leaves of Bontenchiku for fishing gear used by the Fifth Fukuryu-Maru: 40 year after {open_quotes}Bravo{close_quotes}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamamoto, Masayoshi; Komura, Kazuhisa; Ueno, Kaoru

1996-05-01

The alpha radioactive components in the Hemp-palm leaves of Bontenchiku were determined with emphasis on the measurement of low-level {sup 237}Np by alpha-ray spectrometry after chemical separation. Bontenchiku is a kind of fishing gear for long-line fishing used by the Fifth Fukuryu-Maru (Lucky Dragon). This gear was exposed to fallout from the second thermonuclear test explosion (Bravo) at Bikini Atoll in March 1954. The {sup 237}Np content in the Bontenchiku sample was determined to be 11.5 {plus_minus}0.8 mBq g{sup {minus}1} with an activity ratio of {sup 237}Np: {sup 239,240}Pu and an atom ratio of {sup 237}Np: {sup 239}Pu estimated tomore » be (2.2 {plus_minus}0.2) x 10{sup {minus}3} and 0.42 {plus_minus}0.04, respectively. The data showed the existence of a chain reaction of {sup 238}U and its ratio to be {sup 237}Np: {sup 239}Pu, as well as the presence of {sup 237}U at the time of fallout from Bravo event in March 1954. 12 refs., 5 figs., 1 tab.« less

FCRD Transmutation Fuels Handbook 2015

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janney, Dawn Elizabeth; Papesch, Cynthia Ann

2015-09-01

Transmutation of minor actinides such as Np, Am, and Cm in spent nuclear fuel is of international interest because of its potential for reducing the long-term health and safety hazards caused by the radioactivity of the spent fuel. One important approach to transmutation (currently being pursued by the DOE Fuel Cycle Research & Development Advanced Fuels Campaign) involves incorporating the minor actinides into U-Pu-Zr alloys, which can be used as fuel in fast reactors. It is, therefore, important to understand the properties of U-Pu-Zr alloys, both with and without minor actinide additions. In addition to requiring extensive safety precautions, alloysmore » containing U and Pu are difficult to study for numerous reasons, including their complex phase transformations, characteristically sluggish phase-transformation kinetics, tendency to produce experimental results that vary depending on the histories of individual samples, and sensitivity to contaminants such as oxygen in concentrations below a hundred parts per million. Many of the experimental measurements were made before 1980, and the level of documentation for experimental methods and results varies widely. It is, therefore, not surprising that little is known with certainty about U-Pu-Zr alloys, and that general acceptance of results sometimes indicates that there is only a single measurement for a particular property. This handbook summarizes currently available information about U, Pu, Zr, and alloys of two or three of these elements. It contains information about phase diagrams and related information (including phases and phase transformations); heat capacity, entropy, and enthalpy; thermal expansion; and thermal conductivity and diffusivity. In addition to presenting information about materials properties, it attempts to provide information about how well the property is known and how much variation exists between measurements. Although the handbook includes some references to publications about

Temperature dependence of the kinetic energy in the Zr40Be60 amorphous alloy

NASA Astrophysics Data System (ADS)

Syrykh, G. F.; Stolyarov, A. A.; Krzystyniak, M.; Romanelli, G.; Sadykov, R. A.

2017-05-01

The average kinetic energy < E(T)> of the atomic nucleus for each element of the amorphous alloy Zr40Be60 in the temperature range 10-300 K has been measured for the first time using VESUVIO spectrometer (ISIS). The experimental values of < E(T)> have been compared to the partial ZrBe spectra refined by a recursion method based on the data obtained with thermal neutron scattering. The satisfactory agreement has been reached with the calculations using partial spectra based on thermal neutron spectra obtained with recursion method. In addition, the experimental data have been compared to the Debye model. The measurements at different temperatures (10, 200, and 300 K) will provide an opportunity to evaluate the significance of anharmonicity in the dynamics of metallic glasses.

Tumorigenic target cell regions in bone marrow studied by localized dosimetry of 239Pu, 241Am and 233U in the mouse femur.

PubMed

Lord, B I; Austin, A L; Ellender, M; Haines, J W; Harrison, J D

2001-06-01

To study the temporal change in microdistribution of plutonium-239, americium-241 and uranium-233 in the mouse distal femur and to compare and combine calculated radiation doses with those obtained previously for the femoral shaft. Also, to relate doses to relative risks of osteosarcoma and acute myeloid leukaemia. Computer-based image analysis of neutron-induced and alpha-track autoradiographs of sections of mouse femora was used to quantify the microdistribution of (239)Pu, (241)Am and (233)U from 1 to 448 days after intraperitoneal injection. Localized dose-rates and cumulative doses over this period were calculated for different regions of the marrow spaces in trabecular bone. The results were then combined with previous data for doses to the cortical marrow of the femoral shaft. A morphometric analysis of the distal femur was carried out. Initial deposition on endosteal surfaces and dose-rates near to the trabecular surfaces at 1 day were two to four times greater than corresponding results for cortical bone. Burial was most rapid for (233)U, about twice the rate in cortical bone. As in cortical bone, subsequent uptake into the marrow was seen for (239)Pu and (241)Am but not (233)U. Cumulative doses to 448 days for different regions of trabecular marrow were greater than corresponding values for cortical marrow for each radionuclide. Combined doses reflected the greater overall volume of cortical marrow. Cumulative radiation doses to the 10 microm thick band of marrow adjacent to all endosteal surfaces were in the ratio of approximately 7:3:1 for (239)Pu:(241)Am:(233)U. This ratio is not inconsistent with observed incidences of osteosarcoma induction by the three nuclides. Analysis of doses to different depths of marrow, however, showed that although ratios were probably not significantly different to that for a 10 microm depth, better correlations with osteosarcomagenic risk were obtained with 20-40 microm depths. For acute myeloid leukaemia, the closest

The heat of formation of gaseous PuO(2)2+ from relativistic density functional calculations.

PubMed

Moskaleva, Lyudmila V; Matveev, Alexei V; Dengler, Joachim; Rösch, Notker

2006-08-28

Using a set of model reactions, we estimated the heat of formation of gaseous PuO2(2+) from quantum-chemical reaction enthalpies and experimental heats of formation of reference species. To this end, we carried out relativistic density functional calculations on the molecules PuO(2)2+, PuO2, PuF6, and PuF4. We used a revised variant (PBEN) of the Perdew-Burke-Ernzerhof gradient-corrected exchange-correlation functional, and we accounted for spin-orbit interaction in a self-consistent fashion. As open-shell Pu species with two or more unpaired 5f electrons are involved, spin-orbit interaction significantly affects the energies of the model reactions. Our theoretical estimate for the heat of formation DeltafH degree 0(PuO2(2+),g), 418+/-15 kcal mol-1, evaluated using plutonium fluorides as references, is in good agreement with a recent experimental result, 413+/-16 kcal mol-1. The theoretical value connected to the experimental heat of formation of PuO2(g) has a notably higher uncertainty and therefore was not included in the final result.

PLUTONIUM METALLIC FUELS FOR FAST REACTORS

DOE Office of Scientific and Technical Information (OSTI.GOV)

STAN, MARIUS; HECKER, SIEGFRIED S.

2007-02-07

Early interest in metallic plutonium fuels for fast reactors led to much research on plutonium alloy systems including binary solid solutions with the addition of aluminum, gallium, or zirconium and low-melting eutectic alloys with iron and nickel or cobalt. There was also interest in ternaries of these elements with plutonium and cerium. The solid solution and eutectic alloys have most unusual properties, including negative thermal expansion in some solid-solution alloys and the highest viscosity known for liquid metals in the Pu-Fe system. Although metallic fuels have many potential advantages over ceramic fuels, the early attempts were unsuccessful because these fuelsmore » suffered from high swelling rates during burn up and high smearing densities. The liquid metal fuels experienced excessive corrosion. Subsequent work on higher-melting U-PuZr metallic fuels was much more promising. In light of the recent rebirth of interest in fast reactors, we review some of the key properties of the early fuels and discuss the challenges presented by the ternary alloys.« less

Electrowinning of U-Pu onto inert solid cathode in LiCl-KCl eutectic melts containing UCl3 and PuCl3

NASA Astrophysics Data System (ADS)

Sakamura, Yoshiharu; Murakami, Tsuyoshi; Tada, Kohei; Kitawaki, Shinichi

2018-04-01

Electrowinning process was investigated for extracting actinides from molten salts used for the pyrochemical reprocessing of spent nuclear fuels. The separation of actinides from lanthanides is expected to be enhanced by employing inert solid cathodes due to larger potential differences on these cathodes. In this study, the co-deposition behavior of Pu and U metals onto an inert solid cathode made of tungsten was examined in LiCl-KCl eutectic melts containing UCl3 and PuCl3 at 773 K. The standard potential of U3+/U is 0.31 V more positive than that of Pu3+/Pu. The U3+ concentration was varied in the range of 0.11-0.66 wt%, while the Pu3+ concentration was maintained at approximately 2.9 wt%. When the U3+ concentration was not sufficiently low, the deposited U metal readily grew outward from the electrode surface and the electrode surface area rapidly increased, which facilitated only the deposition of U metal. It was estimated that metallic Pu can be efficiently collected along with U at U3+ concentrations lower than ∼0.2 wt%.

Evaluation of Zr(Ni, Mn){sub 2} Laves phase alloys as negative active material for Ni-MH electric vehicle batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knosp, B.; Jordy, C.; Blanchard, P.

1998-05-01

Laves phase alloys of compositions (Zr, Ti)(Ni, Mn, M){sub x} where M = Cr, V, Co, Al, and 1.9 < x < 2.1 with hexagonal C14 or cubic C15 structure have been studied in order to select the most suitable AB{sub 2} alloys as an active material for nickel-metal hydride (Ni-MH) batteries. With the selected alloy, feasibility of MH negative electrodes using industrial technology and containing more than 97% of the alloy powder has been demonstrated. 22 Ah Ni-MH batteries for electric vehicle application have been assembled, and 600 cycles have been achieved at steady C/3 charge and discharge ratesmore » and 80% depth of discharge.« less

Tribological characterisation of Zr-based bulk metallic glass in simulated physiological media

NASA Astrophysics Data System (ADS)

Chen, Q.; Chan, K. C.; Liu, L.

2011-10-01

Due to their excellent wear resistant properties and high strength, as well as a low Young's modulus, Zr-based bulk metallic glasses (BMGs) are potentially suitable biomaterials for low-friction arthroplasty. The wear characteristics of the Zr60.14Cu22.31Fe4.85Al9.7Ag3 bulk amorphous alloy against ultra-high-molecular-weight polyethylene (UHMWPE) compared to a CoCrMo/UHMWPE combination were investigated in two different wear screening test devices, reciprocating and unidirectional. Hank's solution and sterile calf bovine serum were selected as the lubricant fluid media. It was found that different fluid media had insignificant effect on polyethylene wear against BMG counterfaces. The wear behaviour obtained on both test devices demonstrated that Zr-based BMG achieved UHMWPE counterface wear rates superior to conventional cast CoCrMo alloy, where the wear rate of UHMWPE is decreased by over 20 times. The tribological performance of these joints is superior to that of conventional metal-on-polymer designs. Contact angle measurements suggested that the advantage of BMG over a CoCrMo alloy counterface is attributed to its highly hydrophilic surfaces.

Are new TiNbZr alloys potential substitutes of the Ti6Al4V alloy for dental applications? An electrochemical corrosion study.

PubMed

Ribeiro, Ana Lúcia Roselino; Hammer, Peter; Vaz, Luís Geraldo; Rocha, Luís Augusto

2013-12-01

The main aim of this work was to assess the electrochemical behavior of new Ti35Nb5Zr and Ti35Nb10Zr alloys in artificial saliva at 37 °C to verify if they are indicated to be used as biomaterials in dentistry as alternatives to Ti6Al4V alloys in terms of corrosion protection efficiency of the material. Electrochemical impedance spectroscopy (EIS) experiments were carried out for different periods of time (0.5-216 h) in a three-electrode cell, where the working electrode (Ti alloys) was exposed to artificial saliva at 37 °C. The near-surface region of the alloys was investigated using x-ray photoelectron spectroscopy (XPS). All alloys exhibited an increase in corrosion potential with the immersion time, indicating the growth and stabilization of the passive film. Ti35Nb5Zr and Ti6Al4V alloys had their EIS results interpreted by a double-layer circuit, while the Ti35Nb10Zr alloy was modeled by a one-layer circuit. In general, the new TiNbZr alloys showed similar behavior to that observed for the Ti6Al4V. XPS results suggest, in the case of the TiNbZr alloys, the presence of a thicker passive layer containing a lower fraction of TiO2 phase than that of Ti6Al4V. After long-term immersion, all alloys develop a calcium phosphate phase on the surface. The new TiNbZr alloys appear as potential candidates to be used as a substitute to Ti6Al4V in the manufacturing of dental implant-abutment sets.

Determination of (236)U and transuranium elements in depleted uranium ammunition by alpha-spectrometry and ICP-MS.

PubMed

Desideri, D; Meli, M A; Roselli, C; Testa, C; Boulyga, S F; Becker, J S

2002-11-01

It is well known that ammunition containing depleted uranium (DU) was used by NATO during the Balkan conflict. To evaluate the origin of DU (the enrichment of natural uranium or the reprocessing of spent nuclear fuel) it is necessary to directly detect the presence of activation products ((236)U, (239)Pu, (240)Pu, (241)Am, and (237)Np) in the ammunition. In this work the analysis of actinides by alpha-spectrometry was compared with that by inductively coupled plasma mass spectrometry (ICP-MS) after selective separation of ultratraces of transuranium elements from the uranium matrix. (242)Pu and (243)Am were added to calculate the chemical yield. Plutonium was separated from uranium by extraction chromatography, using tri- n-octylamine (TNOA), with a decontamination factor higher than 10(6); after elution plutonium was determined by ICP-MS ((239)Pu and (240)Pu) and alpha-spectrometry ((239+240)Pu) after electroplating. The concentration of Pu in two DU penetrator samples was 7 x 10(-12) g g(-1) and 2 x 10(-11) g g(-1). The (240)Pu/(239)Pu isotope ratio in one penetrator sample (0.12+/-0.04) was significantly lower than the (240)Pu/(239)Pu ratios found in two soil samples from Kosovo (0.35+/-0.10 and 0.27+/-0.07). (241)Am was separated by extraction chromatography, using di(2-ethylhexyl)phosphoric acid (HDEHP), with a decontamination factor as high as 10(7). The concentration of (241)Am in the penetrator samples was 2.7 x 10(-14) g g(-1) and <9.4 x 10(-15) g g(-1). In addition (237)Np was detected at ultratrace levels. In general, ICP-MS and alpha-spectrometry results were in good agreement. The presence of anthropogenic radionuclides ((236)U, (239)Pu,(240)Pu, (241)Am, and (237)Np) in the penetrators indicates that at least part of the uranium originated from the reprocessing of nuclear fuel. Because the concentrations of radionuclides are very low, their radiotoxicological effect is negligible.

Zr/ZrC modified layer formed on AISI 440B stainless steel by plasma Zr-alloying

NASA Astrophysics Data System (ADS)

Shen, H. H.; Liu, L.; Liu, X. Z.; Guo, Q.; Meng, T. X.; Wang, Z. X.; Yang, H. J.; Liu, X. P.

2016-12-01

The surface Zr/ZrC gradient alloying layer was prepared by double glow plasma surface alloying technique to increase the surface hardness and wear resistance of AISI 440B stainless steel. The microstructure of the Zr/ZrC alloying layer formed at different alloying temperatures and times as well as its formation mechanism were discussed by using scanning electron microscopy, glow discharge optical emission spectrum, X-ray diffraction and X-ray photoelectron spectroscopy. The adhesive strength, hardness and tribological property of the Zr/ZrC alloying layer were also evaluated in the paper. The alloying surface consists of the Zr-top layer and ZrC-subsurface layer which adheres strongly to the AISI 440B steel substrate. The thickness of the Zr/ZrC alloying layer increases gradually from 16 μm to 23 μm with alloying temperature elevated from 900 °C to 1000 °C. With alloying time from 0.5 h to 4 h, the alloyed depth increases from 3 μm to 30 μm, and the ZrC-rich alloyed thickness vs time is basically parabola at temperature of 1000 °C. Both the hardness and wear resistance of the Zr/ZrC alloying layer obviously increase compared with untreated AISI 440B steel.

Mechanical relaxations of a Cu60Zr40 metallic glass studied by using a dynamic mechanical analysis

NASA Astrophysics Data System (ADS)

Jeong, H. T.; Park, C. O.

2013-03-01

The mechanical relaxation behaviors of a Cu60Zr40 metallic glass were investigated by using isothermal multi-frequency dynamic mechanical measurements. From the spectra of the elastic moduli, master curves were constructed using the time-temperature superposition principle. The temperature dependence of the shift factor was found to follow the Arrhenius relationship in two temperature regions, one below and the other above the glass transition temperature ( T g ), and the activation energies for low-temperature relaxation and viscous flow were 32.7 kJ/mol and 307.1 kJ/mol, respectively. The decoupling of these two relaxations, shown in the temperature dependent plot of the shift factor, manifests the dynamic glass transition temperature region of the Cu60Zr40 metallic glass. From the temperature dependence of the shift factor, the fragility index of this alloy was also estimated.

Oxygen potential of (U 0.88Pu 0.12)O 2±x and (U 0.7Pu 0.3)O 2±x at high temperatures of 1673-1873 K

NASA Astrophysics Data System (ADS)

Kato, M.; Takeuchi, K.; Uchida, T.; Sunaoshi, T.; Konashi, K.

2011-07-01

The oxygen potential of (U 0.88Pu 0.12)O 2±x (-0.0119 < x < 0.0408) and (U 0.7Pu 0.3)O 2±x (-0.0363 < x < 0.0288) was measured at high temperatures of 1673-1873 K using gas equilibrium method with thermo gravimeter. The measured data were analyzed by a defect chemistry model. Expressions were derived to represent the oxygen potential based on defect chemistry as functions of temperature and oxygen-to-metal ratio. The thermodynamic data, ΔG, ΔH and ΔS, at stoichiometric composition were obtained. The expressions can be used for in situ determination of the oxygen-to-metal ratio by the gas-equilibration method. The calculation results were consistent with measured data. It was estimated that addition of 1 wt.% Pu content increased oxygen potential of uranium and plutonium mixed oxide by 2-5 kJ/mol.

Deviation between the chemistry of Ce(IV) and Pu(IV) and routes to ordered and disordered heterobimetallic 4f/5f and 5f/5f phosphonates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Diwu, Juan; Wang, Shuao; Good, Justin J.

2011-06-06

The heterobimetallic actinide compound UO₂Ce(H₂O)[C₆H₄(PO₃H)₂]₂·H₂O was prepared via the hydrothermal reaction of U(VI) and Ce(IV) in the presence of 1,2-phenylenediphosphonic acid. We demonstrate that this is a kinetic product that is not stable with respect to decomposition to the monometallic compounds. Similar reactions have been explored with U(VI) and Ce(III), resulting in the oxidation of Ce(III) to Ce(IV) and the formation of the Ce(IV) phosphonate, Ce[C₆H₄(PO₃H)(PO₃H₂)][C₆H₄(PO₃H)(PO₃)]·2H₂O, UO₂Ce(H₂O)[C₆H₄(PO₃H)₂]₂·H₂O, and UO₂[C₆H₄(PO₃H)₂](H₂O)·H₂O. In comparison, the reaction of U(VI) with Np(VI) only yields Np[C₆H₄(PO₃H)₂]₂·2H₂O and aqueous U(VI), whereas the reaction of U(VI) with Pu(VI) yields the disordered U(VI)/Pu(VI) compound, (U 0.9Pu 0.1)O₂[C₆H₄(PO₃H)₂](H₂O)·H₂O, and themore » Pu(IV) phosphonate, Pu[C₆H₄(PO₃H)(PO₃H₂)][C₆H₄(PO₃H)(PO₃)]·2H₂O. The reactions of Ce(IV) with Np(VI) yield disordered heterobimetallic phosphonates with both M[C₆H₄(PO₃H)(PO₃H₂)][C₆H₄(PO₃H)(PO₃)]·2H₂O (M = Ce, Np) and M[C₆H₄(PO₃H)₂]₂·2H₂O (M = Ce, Np) structures, as well as the Ce(IV) phosphonate Ce[C₆H₄(PO₃H)(PO₃H₂)][C₆H₄(PO₃H)(PO₃)]·2H₂O. Ce(IV) reacts with Pu(IV) to yield the Pu(VI) compound, PuO₂[C₆H₄(PO₃H)₂](H₂O)·3H₂O, and a disordered heterobimetallic Pu(IV)/Ce(IV) compound with the M[C₆H₄(PO₃H)(PO₃H₂)][C₆H₄(PO₃H)(PO₃)]·2H₂O (M = Ce, Pu) structure. Mixtures of Np(VI) and Pu(VI) yield disordered heterobimetallic Np(IV)/Pu(IV) phosphonates with both the An[C₆H₄(PO₃H)(PO₃H₂)][C₆H₄(PO₃H)(PO₃)]·2H₂O (M = Np, Pu) and An[C₆H₄(PO₃H)₂]₂·2H₂O (M = Np, Pu) formulas.« less

Synthesis, characterization and biological study on Cr(3+), ZrO(2+), HfO(2+) and UO(2)(2+) complexes of oxalohydrazide and bis(3-hydroxyimino)butan-2-ylidene)-oxalohydrazide.

PubMed

El-Asmy, A A; El-Gammal, O A; Radwan, H A

2010-09-01

Cr(3+), ZrO(2+), HfO(2+) and UO(2)(2+) complexes of oxalohydrazide (H(2)L(1)) and oxalyl bis(diacetylmonoxime hydrazone) [its IUPAC name is oxalyl bis(3-hydroxyimino)butan-2-ylidene)oxalohydrazide] (H(4)L(2)) have been synthesized and characterized by partial elemental analysis, spectral (IR; electronic), thermal and magnetic measurements. [Cr(L(1))(H(2)O)(3)(Cl)].H(2)O, [ZrO(HL(1))(2)].C(2)H(5)OH, [UO(2)(L(1))(H(2)O)(2)] [ZrO(H(3)L(2))(Cl)](2).2H(2)O, [HfO(H(3)L(2))(Cl)](2).2H(2)O and [UO(2)(H(2)L(2))].2H(2)O have been suggested. H(2)L(1) behaves as a monobasic or dibasic bidentate ligand while H(4)L(2) acts as a tetrabasic octadentate with the two metal centers. The molecular modeling of the two ligands have been drawn and their molecular parameters were calculated. Examination of the DNA degradation of H(2)L(1) and H(4)L(2) as well as their complexes revealed that direct contact of [ZrO(H(3)L(2))(Cl)](2).2H(2)O or [HfO(H(3)L(2))(Cl)](2).2H(2)O degrading the DNA of Eukaryotic subject. The ligands and their metal complexes were tested against Gram's positive Bacillus thuringiensis (BT) and Gram's negative (Escherichia coli) bacteria. All compounds have small inhibitory effects. Copyright 2010 Elsevier B.V. All rights reserved.

Enhancements to BISON U-Zr Metallic Fuel X447 Example Problem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galloway, Jack D.; Matthews, Christopher; Unal, Cetin

As development of a metallic fuel modeling capability in BISON has progressed, the need for an example problem used as a comparison basis was observed. Collaborative work between researchers at Los Alamos National Laboratory (LANL) and Idaho National Laboratory (INL) then proceeded to determine a viable rod to use as the basis and create a BISON input deck utilizing as many metallic fuel models as feasible. The basis chosen was what would be considered a generic rod from subassembly X447, an assembly irradiated in EBR-II towards the end of its operating life, heavily based on reported data for fuel pinmore » DP11. Thus, the approach was adopted to use flow characteristics from subassembly X447 as a basis for the convective heat transfer solution, power history and axial power profiles that are representative of rod DP11 from subassembly X447. The rod simulated is a U-10Zr wt% (U-22.5Zr at%) composition. A 2D-RZ mesh would be used to capture axial thermal hydraulic effects, axial swelling and stress-strain calculations over the full length of the rod. After initial work was invested, a refinement of the various models and input parameters was conducted to ensure consistency between operator-declared conditions, model input requirements and those represented in the example problem. This report serves as a synopsis of the enhancements and refinements to the example problem conducted throughout the 2016 fiscal year.« less

Actinide Oxidation State and O/M Ratio in Hypostoichiometric Uranium-Plutonium-Americium U0.750Pu0.246Am0.004O2-x Mixed Oxides.

PubMed

Vauchy, Romain; Belin, Renaud C; Robisson, Anne-Charlotte; Lebreton, Florent; Aufore, Laurence; Scheinost, Andreas C; Martin, Philippe M

2016-03-07

Innovative americium-bearing uranium-plutonium mixed oxides U1-yPuyO2-x are envisioned as nuclear fuel for sodium-cooled fast neutron reactors (SFRs). The oxygen-to-metal (O/M) ratio, directly related to the oxidation state of cations, affects many of the fuel properties. Thus, a thorough knowledge of its variation with the sintering conditions is essential. The aim of this work is to follow the oxidation state of uranium, plutonium, and americium, and so the O/M ratio, in U0.750Pu0.246Am0.004O2-x samples sintered for 4 h at 2023 K in various Ar + 5% H2 + z vpm H2O (z = ∼ 15, ∼ 90, and ∼ 200) gas mixtures. The O/M ratios were determined by gravimetry, XAS, and XRD and evidenced a partial oxidation of the samples at room temperature. Finally, by comparing XANES and EXAFS results to that of a previous study, we demonstrate that the presence of uranium does not influence the interactions between americium and plutonium and that the differences in the O/M ratio between the investigated conditions is controlled by the reduction of plutonium. We also discuss the role of the homogeneity of cation distribution, as determined by EPMA, on the mechanisms involved in the reduction process.

Analysis of oxygen potential of (U 0.7Pu 0.3)O 2±x and (U 0.8Pu 0.2)O 2±x based on point defect chemistry

NASA Astrophysics Data System (ADS)

Kato, Masato; Konashi, Kenji; Nakae, Nobuo

2009-06-01

Stoichiometries in (U 0.7Pu 0.3)O 2±x and (U 0.8Pu 0.2)O 2±x were analyzed with the experimental data of oxygen potential based on point defect chemistry. The relationship between the deviation x of stoichiometric composition and the oxygen partial pressure P was evaluated using a Kröger-Vink diagram. The concentrations of the point defects in uranium and plutonium mixed oxide (MOX) were estimated from the measurement data of oxygen potentials as functions of temperature and P. The analysis results showed that x was proportional to PO2±1/2 near the stoichiometric region of both (U 0.7Pu 0.3)O 2±x and (U 0.8Pu 0.2)O 2±x, which suggested that intrinsic ionization was the dominant defect. A model to calculate oxygen potential was derived and it represented the experimental data accurately. Further, the model estimated the thermodynamic data, ΔH and ΔS, of stoichiometric (U 0.7Pu 0.3)O 2.00 and (U 0.8Pu 0.2)O 2.00 as -552.5 kJ·mol -1 and -149.7 J·mol -1, and -674.0 kJ · mol -1 and -219.4 J · mol -1, respectively.

Fine Structure in Multi-Phase Zr8Ni21-Zr7Ni10-Zr2Ni7 Alloy Revealed by Transmission Electron Microscope

PubMed Central

Shen, Haoting; Bendersky, Leonid A.; Young, Kwo; Nei, Jean

2015-01-01

The microstructure of an annealed alloy with a Zr8Ni21 composition was studied by both scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The presence of three phases, Zr8Ni21, Zr2Ni7, and Zr7Ni10, was confirmed by SEM/X-ray energy dispersive spectroscopy compositional mapping and TEM electron diffraction. Distribution of the phases and their morphology can be linked to a multi-phase structure formed by a sequence of reactions: (1) L → Zr2Ni7 + L’; (2) peritectic Zr2Ni7 + L’ → Zr2Ni7 + Zr8Ni21 + L”; (3) eutectic L” → Zr8Ni21 + Zr7Ni10. The effect of annealing at 960 °C, which was intended to convert a cast structure into a single-phase Zr8Ni21 structure, was only moderate and the resulting alloy was still multi-phased. TEM and crystallographic analysis of the Zr2Ni7 phase show a high density of planar (001) defects that were explained as low-energy boundaries between rotational variants and stacking faults. The crystallographic features arise from the pseudo-hexagonal structure of Zr2Ni7. This highly defective Zr2Ni7 phase was identified as the source of the broad X-ray diffraction peaks at around 38.4° and 44.6° when a Cu-K was used as the radiation source. PMID:28793460

Electrochemical studies on zirconium and its biocompatible alloys Ti-50Zr at.% and Zr-2.5Nb wt.% in simulated physiologic media.

PubMed

Oliveira, Nilson T C; Biaggio, Sonia R; Rocha-Filho, Romeu C; Bocchi, Nerilso

2005-09-01

Different electrochemical studies were carried out for Zr and its biocompatible alloys Ti-50Zr at.% and Zr-2.5Nb wt.% in solutions simulating physiologic media, Ringer and PBS (phosphate buffered saline) solutions. The results from rest-potential measurements showed that the three materials are spontaneously passivated in both solutions and that the Ti-50Zr alloy has the greatest tendency for spontaneous oxide formation. Some corrosion parameters (such as the pitting and repassivation potentials) were obtained via cyclic voltammetry in both solutions, revealing that the Ti-50Zr has the best corrosion protection while Zr has the worst. On the other hand, the pre-anodization (up to 8 V vs. SCE) of the alloys in a 0.15 mol/L Na2SO4 solution led to a significant improvement in their protection against pitting corrosion when exposed to the Ringer solution. Elemental analyses by EDX showed that during pitting corrosion, there is no preferential corrosion of any of the alloying elements (Zr, Ti, Nb). Copyright (c) 2005 Wiley Periodicals, Inc.

Interdiffusion and reaction between U and Zr

NASA Astrophysics Data System (ADS)

Park, Y.; Newell, R.; Mehta, A.; Keiser, D. D.; Sohn, Y. H.

2018-04-01

The microstructural development and diffusion kinetics were examined for the binary U vs. Zr system using solid-to-solid diffusion couples, U vs. Zr, annealed at 580 °C for 960 h, 650 °C for 480 h, 680 °C for 240 h, and 710 °C for 96 h. Scanning and transmission electron microscopies with X-ray energy dispersive spectroscopy were employed for detailed microstructural and compositional analyses. Interdiffusion and reaction in U vs. Zr diffusion couples primarily produced: δ-UZr2 solid solution (hP3) and α‧-U at 580 °C; and (γU,βZr) solid solution (cI2) and α‧-U at 650°, 680° and 710 °C. The α‧-phase was confirmed as a reduced variant of the α-U orthorhombic structure with lattice parameters, a × b × c = 2.65 × 5.40 × 4.75 (Å) with a negligible solubility for Zr at room temperature. Concentration profiles were examined to determine interdiffusion coefficients, integrated interdiffusion coefficients, and intrinsic diffusion coefficients using Boltzmann-Matano, Wagner, and Heumann analyses, respectively. Composition-dependence of interdiffusion coefficients were documented for α-U, δ-UZr2 (at 580 °C) and (γU,βZr) solid solution (at 650°, 680° and 710 °C). U was determined to intrinsically diffuse faster than Zr, approximately by an order of magnitude, in the δ-UZr2 at 580 °C, and (γU,βZr) phases at 650°, 680° and 710 °C. Based on Darken's approach, thermodynamic data available in literature were coupled to estimate the tracer diffusion coefficients and atomic mobilities of U and Zr.

Phase Transitions in Tetramethylammonium Hexachlorometalate Compounds (TMA) 2MCl 6 (M = U, Np, Pt, Sn, Hf, Zr)

DOE PAGES

Autillo, Matthieu; Wilson, Richard E.

2017-09-22

A study of the phase transitions occurring in tetramethylammonium hexachlorometalate compounds with M = U IV, Np IV, Zr IV, Sn IV, Hf IV and Pt IV were performed using single-crystal X-ray diffraction across the temperature range 120 - 400K. When the crystals were cooled, movement of the octahedral [MCl 6] 2- anions induces a phase transition from Fm3m to Fd3c with a doubling of the unit cell. For the actinide compounds, no correlation between the f-electron configuration and the transition temperature was observed, instead, a correlation between the transition temperatures and both the [MCl 6] 2- anion and themore » TMA cation size is highlighted. Two phase transitions were observed and characterized. The first phase transition occurs with the ordering of the TMA cation and the second from a rotation of the [MCl 6] 2- octahedra. A third phase transition was observed at lower temperatures and was ascribed to a tetragonal distortion of the [MCl 6] 2- anions. Synthesis and study of their deuterated compounds did not show a significant isotope effect. As a result, Raman spectra performed on the protonated and deuterated compounds indicate only weak hydrogen bonding interactions between the TMA cations and the [MCl 6] 2- octahedra.« less

Vaporization chemistry of hypo-stoichiometric (U,Pu)O 2

NASA Astrophysics Data System (ADS)

Viswanathan, R.; Krishnaiah, M. V.

2001-04-01

Calculations were performed on hypo-stoichiometric uranium plutonium di-oxide to examine its vaporization behavior as a function of O/ M ( M= U+ Pu) ratio and plutonium content. The phase U (1- y) Pu yO z was treated as an ideal solid solution of (1- y)UO 2+ yPuO (2- x) such that x=(2- z)/ y. Oxygen potentials for different desired values of y, z, and temperature were used as the primary input to calculate the corresponding partial pressures of various O-, U-, and Pu-bearing gaseous species. Relevant thermodynamic data for the solid phases UO 2 and PuO (2- x) , and the gaseous species were taken from the literature. Total vapor pressure varies with O/M and goes through a minimum. This minimum does not indicate a congruently vaporizing composition. Vaporization behavior of this system can at best be quasi-congruent. Two quasi-congruently vaporizing compositions (QCVCs) exist, representing the equalities (O/M) vapor=(O/M) mixed-oxide and (U/Pu) vapor=(U/Pu) mixed-oxide, respectively. The (O/M) corresponding to QCVC1 is lower than that corresponding to QCVC2, but very close to the value where vapor pressure minimum occurs. The O/M values of both QCVCs increase with decrease in plutonium content. The vaporization chemistry of this system, on continuous vaporization under dynamic condition, is discussed.

Nanocrystalline Fe/Zr alloys: preparation by using mechanical alloying and mechanical milling processes

NASA Astrophysics Data System (ADS)

Rodríguez, V. A. Peña; Medina, J. Medina; Marcatoma, J. Quispe; Ayala, Ch. Rojas; Landauro, C. V.; Baggio-Saitovitch, E. M.; Passamani, E. C.

2011-11-01

Nanocrystalline Fe/Zr alloys have been prepared after milling for 9 h the mixture of elemental Fe and Zr powders or the arc-melting produced Fe2Zr alloy by using mechanical alloying and mechanical milling techniques, respectively. X-ray and Mössbauer results of the Fe and Zr powders, mechanically alloyed, suggest that amorphous Fe2Zr phase and \\upalpha-Fe(Zr) nanograins have been produced with relative concentrations of 91% and 9%, respectively. Conversely, the results of the mechanically milled Fe2Zr alloy indicate that nanograins of the Fe2Zr alloy have been formed, surrounded by a magnetic inter-granular phase that are simultaneously dispersed in a paramagnetic amorphous phase.

Computational alloy design of (Co1-xNix)88Zr7B4Cu1 nanocomposite soft magnets

NASA Astrophysics Data System (ADS)

Dong, B.; Healy, J.; Lan, S.; Daniil, M.; Willard, M. A.

2018-05-01

The dependence of coercivity on composition is an important factor for establishing optimized soft magnetic properties. In this study, we have used the random anisotropy and coherent rotation models to estimate the variation of coercivity with composition in (Co1-xNix)88Zr7B4Cu1 nanocomposite alloys. Our calculations that the magnetoelastic anisotropy contribution to coercivity dominates for Ni rich compositions (x > 0.5). A small range of compositions (0.65 < x < 0.75) is predicted to result in low values of coercivity (<10 A/m). To validate this prediction, (Co1-xNix)88Zr7B4Cu1 nanocomposites in this range were prepared by melt spinning followed by 3600 s isothermal annealing at the primary crystallization peak temperature (˜673 K). Hysteresis loops were measured using vibrating sample magnetometry at room temperature and saturation magnetostriction was measured using a strain gage based magnetostrictometer. Moderately small coercivities (30-40 A/m) and magnetostrictions (3-4 ppm) were measured at for samples with 0.685 < x < 0.725. Our measured coercivity had a minimum value of 32 A/m at x = 0.725, a shift in composition of about 5 at% in the direction of higher Ni content and without the anticipated low value of coercivity. Several reasons for the inaccuracy of this approach are described, including: ignored contributions from amorphous phase (especially in magnetoealstic anisotropy), composition segregation during crystallization leading to unpredictable compositional shifts in prediction, and the general observation that the predictability of minimum coercivity from minimal combined anisotropies has unexplained deviation even in far less complicated materials.

DFT+U Study of Chemical Impurities in PuO 2

DOE PAGES

Hernandez, Sarah C.; Holby, Edward F.

2016-05-24

In this paper, we employ density functional theory to explore the effects of impurities in the fluorite crystal structure of PuO 2. The impurities that were considered are known impurities that exist in metallic δ-phase Pu, including H, C, Fe, and Ga. These impurities were placed at various high-symmetry sites within the PuO 2 structure including an octahedral interstitial site, an interstitial site with coordination to two neighboring O atoms, an O substitutional site, and a Pu substitutional site. Incorporation energies were calculated to be energetically unfavorable for all sites except the Pu substitutional site. When impurities were placed inmore » a Pu substitutional site, complexes incorporating the impurities and O formed within the PuO 2 structure. The observed defect-oxygen structures were OH, CO 3, FeO 5, and GaO 3. The presence of these defects led to distortion of the surrounding O atoms within the structure, producing long-range disorder of O atoms. In contrast, perturbations of Pu atoms had a relatively short-range effect on the relaxed structures. These effects are demonstrated via radial distribution functions for O and Pu vacancies. Calculated electronic structure revealed hybridization of the impurity atom with the O valence states and a relative decrease in the Pu 5f states. Minor differences in band gaps were observed for the defected PuO 2 structures containing H, C, and Ga. Finally, Fe-containing structures, however, were calculated to have a significantly decreased band gap, where the implementation of a Hubbard U parameter on the Fe 3d orbitals will maintain the calculated PuO 2 band gap.« less

Recovery of UO{sub 2}/PuO{sub 2} in IFR electrorefining process

DOEpatents

Tomczuk, Z.; Miller, W.E.

1992-01-01

This invention is comprised of a process for converting PuO{sub 2} and U0{sub 2} present in an electrorefiner to the chlorides, by contacting the PuO{sub 2} and U0{sub 2} with Li metal in the presence of an alkali metal chloride salt substantially free of rare earth and actinide chlorides for a time and at a temperature sufficient to convert the U0{sub 2} and PuO{sub 2} to metals while converting Li metal to Li{sub 2}O. Li{sub 2}O is removed either by reducing with rare earth metals or by providing an oxygen electrode for transporting 0{sub 2} out of the electrorefiner and a cathode, and thereafter applying an emf to the electrorefiner electrodes sufficient to cause the Li{sub 2}O to disassociate to 0{sub 2} and Li metal but insufficient to decompose the alkali metal chloride salt. The U and Pu and excess lithium are then converted to chlorides by reaction with CdCl{sub 2}.

Constituent Redistribution in U-Zr Metallic Fuel Using the Advanced Fuel Performance Code BISON

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galloway, Jack D.; Unal, Cetin; Matthews, Christopher

2016-09-30

Previous work done by Galloway, et. al. on EBR-II ternary (U-Pu-Zr) fuel constituent redistribution yielded accurate simulation data for the limited data sets of Zr redistribution. The data sets included EPMA scans of two different irradiated rods. First, T179, which was irradiated to 1.9 at% burnup, was analyzed. Second, DP16, which was irradiated to 11 at% burnup, was analyzed. One set of parameters that most accurately represented the zirconium profiles for both experiments was determined. Since the binary fuel (U-Zr) has previously been used as the driver fuel for sodium fast reactors (SFR) as well as being the likely drivermore » fuel if a new SFR is constructed, this same process has been initiated on the binary fuel form. From limited binary EPMA scans as well as other fuel characterization techniques, it has been observed that zirconium redistribution also occurs in the binary fuel, albeit at a reduced rate compared to observation in the ternary fuel, as noted by Kim et. al. While the rate of redistribution has been observed to be slower, numerous metallographs of U-Zr fuel show distinct zone formations.« less

Observations of a Cast Cu-Cr-Zr Alloy

NASA Technical Reports Server (NTRS)

Ellis, David L.

2006-01-01

Prior work has demonstrated that Cu-Cr-Nb alloys have considerable advantages over the copper alloys currently used in regeneratively cooled rocket engine liners. Observations indicated that Zr and Nb have similar chemical properties and form very similar compounds. Glazov and Zakharov et al. reported the presence of Cr2Zr in Cu-Cr-Zr alloys with up to 3.5 wt% Cr and Zr though Zeng et al. calculated that Cr2Zr could not exist in a ternary Cu-Cr-Zr alloy. A cast Cu-6.15 wt% Cr-5.25 wt% Zr alloy was examined to determine if the microstructure developed would be similar to GRCop-84 (Cu-6.65 wt% Cr-5.85 wt% Nb). It was observed that the Cu-Cr-Zr system did not form any Cr2Zr even after a thermal exposure at 875 C for 176.5 h. Instead the alloy consisted of three phases: Cu, Cu5Zr, and Cr.

Development in corrosion resistance by microstructural refinement in Zr-16 SS 304 alloy using suction casting technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, N., E-mail: nirupamd@barc.gov.in; Sengupta, P.; Abraham, G.

Highlights: • Grain refinement was made in Zr–16 wt.% SS alloy while prepared by suction casting process. • Distribution of Laves phase, e.g., Zr{sub 2}(Fe, Cr) was raised in suction cast (SC) Zr–16 wt.% SS. • Corrosion resistance was improved in SC alloy compared to that of arc-melt-cast alloy. • Grain refinement in SC alloy assisted for an increase in its corrosion resistance. - Abstract: Zirconium (Zr)-stainless steel (SS) hybrid alloys are being considered as baseline alloys for developing metallic-waste-form (MWF) with the motivation of disposing of Zr and SS base nuclear metallic wastes. Zr–16 wt.% SS, a MWF alloymore » optimized from previous studies, exhibit significant grain refinement and changes in phase assemblages (soft phase: Zr{sub 2}(Fe, Cr)/α-Zr vs. hard phase: Zr{sub 3}(Fe, Ni)) when prepared by suction casting (SC) technique in comparison to arc-cast-melt (AMC) route. Variation in Cr-distribution among different phases are found to be low in suction cast alloy, which along with grain refinement restricted Cr-depletion at the Zr{sub 2}(Fe, Cr)/Zr interfaces, prone to localized attack. Hence, SC alloy, compared to AMC alloy, showed lower current density, higher potential at the breakdown of passivity and higher corrosion potential during polarization experiments (carried out under possible geological repository environments, viz., pH 8, 5 and 1) indicating its superior corrosion resistance.« less

The crystal structure of ianthinite, [U 24+(UO 2) 4O 6(OH) 4(H 2O) 4](H 2O) 5: a possible phase for Pu 4+ incorporation during the oxidation of spent nuclear fuel

NASA Astrophysics Data System (ADS)

Burns, Peter C.; Finch, Robert J.; Hawthorne, Frank C.; Miller, Mark L.; Ewing, Rodney C.

1997-10-01

Ianthinite, [U 24+(UO 2) 4O 6(OH) 4(H 2O) 4](H 2O) 5, is the only known uranyl oxide hydrate mineral that contains U 4+, and it has been proposed that ianthinite may be an important Pu 4+-bearing phase during the oxidative dissolution of spent nuclear fuel. The crystal structure of ianthinite, orthorhombic, a = 0.7178(2), b = 1.1473(2), c = 3.039(1) nm, V = 2.5027 nm 3Z = 4, space group P2 1cn, has been solved by direct methods and refined by least-squares methods to an R index of 9.7% and a wR index of 12.6% using 888 unique observed [| F| ≥ 5 σ | F|] reflections. The structure contains both U 4+. The U 6+ cations are present as roughly linear (U 6+O 2) 2+ uranyl ion (Ur) that are in turn coordinated by five O 2- and OH - located at the equatorial positions of pentagonal bipyramids. The U 4+ cations are coordinated by O 2-, OH - and H 2O in a distorted octahedral arrangement. The Ur φ5and U 4+| 6 (φ: O 2-, OH -, H 2O) polyhedra l sharing edges to for two symmetrically distinct sheets at z ≈ 0.0 and z ≈ 0.25 that are parallel to (001). The sheets have the β-U 3O 8 sheet anion-topology. There are five symmetrically distinct H 2O groips located at z ≈ 0.125 between the sheets of U φn polyhedra, and the sheets of U φn polyhedra are linked together only by hydrogen bonding to the intersheet H 2O groups. The crystal-chemical requirements of U 4+ and Pu 4+ are very similar, suggesting that extensive Pu 4+ ↔ U 4+ substitution may occur within the sheets of U φn polyhedra in trh structure of ianthinine.

Method for separating actinides. [Patent application; stripping of Np from organic extractant

DOEpatents

Friedman, H.A.; Toth, L.M.

1980-11-10

An organic solution used for processing spent nuclear reactor fuels is contacted with an aqueous nitric acid solution to strip Np(VI), U(VI), and Pu(IV) from the organic solution into the acid solution. The acid solution is exposed to ultraviolet light, which reduces Np(VI) to Np(V) without reducing U(VI) and Pu(IV). Since the solubility of Np(V) in the organic solution is much lower than that of Np(VI), U(VI), and Pu(IV), a major part of the Np is stripped from the organic solution while leaving most of the U and Pu therein.

Biomimetic Hydroxyapatite Growth on Functionalized Surfaces of Ti-6Al-4V and Ti-Zr-Nb Alloys

NASA Astrophysics Data System (ADS)

Pylypchuk, Ie V.; Petranovskaya, A. L.; Gorbyk, P. P.; Korduban, A. M.; Markovsky, P. E.; Ivasishin, O. M.

2015-08-01

A biomimetic approach for coating titanium-containing alloys with hydroxyapatite (HA) is reported in the article. Two types of Ti-containing alloys were chosen as an object for coating: Ti-6Al-4V (recommended for orthopedic application) and a novel highly biocompatible Ti-Zr-Nb alloy, with good mechanical compatibility due to a modulus that is more close to that of human bones (E ≈ 50 GPa instead of 110 GPa in Ti-6Al-4V). Coating process was carried out in a 10×-concentrated simulated body fluid (SBF)—synthetic analog of human body plasma. The effect of oxidized and carboxylated alloy surface on formation of biomimetic hydroxyapatite has been studied. By XRD, we found influence of thermal conditions on HA crystal formation and size. SEM images and Fourier transform infrared confirmed that hydroxyapatite with different morphology, crystallinity, and Ca/P ratio formed on metallic surfaces. X-ray photoelectron spectroscopy showed that in the Ti-6AL-4V sample the observed Ca/P ratio reach 0.97, whereas in the Ti-Zr-Nb sample the observed Ca/P ratio reach 1.15.

Development of High Strength Ni-Cu-Zr-Ti-Si-Sn In-Situ Bulk Metallic Glass Composites Reinforced by Hard B2 Phase

NASA Astrophysics Data System (ADS)

Park, Hyo Jin; Hong, Sung Hwan; Park, Hae Jin; Kim, Young Seok; Kim, Jeong Tae; Na, Young Sang; Lim, Ka Ram; Wang, Wei-Min; Kim, Ki Buem

2018-03-01

In the present study, the influence of atomic ratio of Zr to Ti on the microstructure and mechanical properties of Ni-Cu-Zr-Ti-Si-Sn alloys is investigated. The alloys were designed by fine replacement of Ti for Zr from Ni39Cu20Zr36-xTixSi2Sn3. The increase of Ti content enhances glass forming ability of the alloy by suppression of formation of (Ni, Cu)10(Zr, Ti)7 phase during solidification. With further increasing Ti content up to 24 at.%, the B2 phase is introduced in the amorphous matrix with a small amount of B19' phase from alloy melt. The bulk metallic glass composite containing B2 phase with a volume fraction of 10 vol% exhibits higher fracture strength ( 2.5 GPa) than that of monolithic bulk metallic glass ( 2.3 GPa). This improvement is associated to the individual mechanical characteristics of the B2 phase and amorphous matrix. The B2 phase exhibits higher hardness and modulus than those of amorphous matrix as well as effective stress accommodation up to the higher stress level than the yield strength of amorphous matrix. The large stress accommodation capacity of the hard B2 phase plays an important factor to improve the mechanical properties of in situ Ni-based bulk metallic glass composites.

Alloying effect on the room temperature creep characteristics of a Ti-Zr-Be bulk metallic glass

NASA Astrophysics Data System (ADS)

Gong, Pan; Wang, Sibo; Li, Fangwei; Wang, Xinyun

2018-02-01

The effect of alloying elements (e.g. Fe, Al, and Ni) on the room temperature creep behavior of a lightweight Ti41Zr25Be34 bulk metallic glass (BMG) was investigated via nanoindentation tests. The generalized Kelvin model was adopted to describe the creep curves. The strain rate sensitivity m has been derived as a measure of the creep resistance. The compliance spectrum and retardation spectrum were also derived. The results show that the creep resistance of Ti41Zr25Be34 alloy can be obviously improved with the addition of alloying elements, and the most effective element is found to be Al. The mechanism for enhancing the creep resistance was discussed in terms of the scale variation of the shear transformation zone induced by alloying.

Interdiffusion and reactions between U-Mo and Zr at 650 °C as a function of time

NASA Astrophysics Data System (ADS)

Park, Y.; Keiser, D. D.; Sohn, Y. H.

2015-01-01

Development of monolithic U-Mo alloy fuel (typically U-10 wt.%Mo) for the Reduced Enrichment for Research and Test Reactors (RERTR) program entails a use of Zr diffusion barrier to eliminate the interdiffusion-reactions between the fuel alloy and Al-alloy cladding. The application of Zr barrier to the U-Mo fuel system requires a co-rolling process that utilizes a soaking temperature of 650 °C, which represents the highest temperature the fuel system is exposed to during both fuel manufacturing and reactor application. Therefore, in this study, development of phase constituents, microstructure and diffusion kinetics of U-10 wt.%Mo and Zr was examined using solid-to-solid diffusion couples annealed at 650 °C for 240, 480 and 720 h. Phase constituents and microstructural development were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Concentration profiles were mapped as diffusion paths on the isothermal ternary phase diagram. Within the diffusion zone, single-phase layers of β-Zr and β-U were observed along with a discontinuous layer of Mo2Zr between the β-Zr and β-U layers. In the vicinity of Mo2Zr phase, islands of α-Zr phases were also found. In addition, acicular α-Zr and U6Zr3Mo phases were observed within the γ-U(Mo) terminal alloy. Growth rate of the interdiffusion-reaction zone was determined to be 7.75 (± 5.84) × 10-16 m2/s at 650 °C, however with an assumption of a certain incubation period.

Formation and structure of Al-Zr metallic glasses studied by Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Li, J. H.; Zhao, S. Z.; Dai, Y.; Cui, Y. Y.; Liu, B. X.

2011-06-01

Based on the recently constructed n-body potential, both molecular dynamics and Monte Carlo simulations revealed that the Al-Zr amorphous alloy or metallic glass can be obtained within the composition range of 24-66 at. % Zr. The revealed composition range could be considered the intrinsic glass-forming range and it quantitatively indicates the glass-forming ability of the Al-Zr system. The underlying physics of the finding is that, within the composition range, the amorphous alloys are energetically favored to form. In addition, it is proposed that the energy difference between a solid solution and the amorphous phase could serve as the driving force of the crystalline to amorphous transition and the driving force should be sufficiently large for amorphization to take place. The minimum driving forces for fcc Al-based and hcp Zr-based Al-Zr solid solutions to amorphize are calculated to be about -0.05 and -0.03 eV/atom, respectively, whereas the maximum driving force is found to be -0.23 eV/atom at the alloy stoichiometry of Al60Zr40. A thermodynamics parameter γ¯, defined as the ratio of the driving force to the formation energy of the solid solution, is further proposed to indicate the glass-forming ability of an Al-Zr alloy. Thermodynamics calculations show that the glass-forming ability of the Al56Zr44 alloy is the largest, implying that the Al56Zr44 amorphous alloy is more ready to form than other alloys in the Al-Zr system. Besides, Voronoi analysis found that there exists a strong correlation between the coordinate number and structure. Amorphization could result in increase of coordinate numbers and about 1.5% volume-expansion. The volume-expansion induced by amorphization can be attributed to two factors, i.e., the total bond number of the Al-Zr amorphous phase is greater than that of the corresponding solid solution, and the averaged bond length of the Al-Zr amorphous phase is longer than that of the corresponding solid solution. For the Al-Zr alloys

Bone bonding bioactivity of Ti metal and Ti-Zr-Nb-Ta alloys with Ca ions incorporated on their surfaces by simple chemical and heat treatments.

PubMed

Fukuda, A; Takemoto, M; Saito, T; Fujibayashi, S; Neo, M; Yamaguchi, S; Kizuki, T; Matsushita, T; Niinomi, M; Kokubo, T; Nakamura, T

2011-03-01

Ti15Zr4Nb4Ta and Ti29Nb13Ta4.6Zr, which do not contain the potentially cytotoxic elements V and Al, represent a new generation of alloys with improved corrosion resistance, mechanical properties, and cytocompatibility. Recently it has become possible for the apatite forming ability of these alloys to be ascertained by treatment with alkali, CaCl2, heat, and water (ACaHW). In order to confirm the actual in vivo bioactivity of commercially pure titanium (cp-Ti) and these alloys after subjecting them to ACaHW treatment at different temperatures, the bone bonding strength of implants made from these materials was evaluated. The failure load between implant and bone was measured for treated and untreated plates at 4, 8, 16, and 26 weeks after implantation in rabbit tibia. The untreated implants showed almost no bonding, whereas all treated implants showed successful bonding by 4 weeks, and the failure load subsequently increased with time. This suggests that a simple and economical ACaHW treatment could successfully be used to impart bone bonding bioactivity to Ti metal and Ti-Zr-Nb-Ta alloys in vivo. In particular, implants heat treated at 700 °C exhibited significantly greater bone bonding strength, as well as augmented in vitro apatite formation, in comparison with those treated at 600 °C. Thus, with this improved bioactive treatment process these advantageous Ti-Zr-Nb-Ta alloys can serve as useful candidates for orthopedic devices. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Thermoelectric power of Fe-Zr and Co-Zr metallic glasses

NASA Astrophysics Data System (ADS)

From, M.; Muir, W. B.

1986-03-01

The thermopower of Fe1-xZrx (0.57metallic glasses has been measured from 4 to 300 K. Compositions near the critical composition for ferromagnetism are found to have thermopowers which are very nonlinear in temperature. The nonlinearities are tied to the presence of spin fluctuations in these alloys. However, the form of the spin-fluctuation thermopower observed in Fe-Zr and Co-Zr glasses is significantly different from that previously observed in crystalline materials.

Effects of Zr and Si on the Glass Forming Ability and Compressive Properties of Ti-Cu-Co-Sn Alloys

NASA Astrophysics Data System (ADS)

Wang, Tan; Wu, Yidong; Si, Jiajia; Hui, Xidong

2015-06-01

To succeed in finding novel Ti-based bulk metallic glasses, which are free from Be, Ni, and noble metallic elements, a comprehensive study was performed on the effects of Zr and Si on the microstructural evolution, glass-forming ability (GFA), and mechanical properties of Ti46Cu44- x Zr x Co7Sn3 ( x = 0, 5, 10, 12.5, and 16 at. pct) and Ti46Cu31.5Zr12.5- x Co7Sn3Si x ( x = 0.5, 1, and 1.5 at. pct) alloys. It is shown that with the increase of Zr, the sequence of phase formation is β-Ti + α-Ti + (Ti, Zr)3Cu4 ⇒ β-Ti + α-Ti + TiCu ⇒ β-Ti + Ti2Cu + glass ⇒ glass ⇒ β-Ti + Ti2Cu + TiCuSn. The quinary Ti-Zr-Cu-Co-Sn alloy with 12.5 pct Zr exhibits the best GFA. The addition of 1 pct Si results in the improvement of the critical size of glassy rods up to 3 mm in diameter. The yield stress and Young's modulus of Z-series alloys increases, and the plastic strain decreases with the addition of Zr. The yield stress and ultimate compression stress of Ti46Zr11.5Cu31.5Co7Sn3Si1 glassy alloy reach 2477.9 and 2623.3 MPa, respectively. It was found that the addition of Si promotes the generation and multiplication of shear bands, resulting in certain plasticity in these kinds of glassy alloys.

Effects of vacuum and ageing on Zr4/Cr3 based conversion coatings on aluminium alloys

NASA Astrophysics Data System (ADS)

Thirupathi, Kalaivanan; Bárczy, Pál; Vad, Kálmán; Csik, Attila; Somosvári, Béla Márton

2018-05-01

In this study, we investigate the impact of ageing and high vacuum on existing environmentally friendly Zr4/Cr3-based conversion coatings. The freshly formed coating undergoes several changes during ageing and exposure to high vacuum. Based on the present data, we propose that the coating formed over AA6082 and AA7075 alloys is sol-gel in nature, confirmed by secondary neutral mass spectroscopy (SNMS) using the depth profiling technique. Our findings reveal that there are elemental level changes that result in shrinkage of the coating. Most Zr ions in the coating are in the solute form, with lesser number of Cr and Al ions that disappear under high vacuum over a certain period of time. The remaining Cr, Zr and O atoms exist in a gelatinous state. During ageing, there is a continuous transition of ions from solute to gelatinous state. In addition, the deposition of coating ions is directly influenced by the substrates and their constituents. The extent of dissolution of aluminium in the conversion bath determines both Zr and Cr ion deposition. For a highly alloyed metal like AA7075, the dissolution rate is disturbed by copper and zinc.

Microstructure, mechanical properties, in vitro degradation and cytotoxicity evaluations of Mg-1.5Y-1.2Zn-0.44Zr alloys for biodegradable metallic implants.

PubMed

Fan, Jun; Qiu, Xin; Niu, Xiaodong; Tian, Zheng; Sun, Wei; Liu, Xiaojuan; Li, Yangde; Li, Weirong; Meng, Jian

2013-05-01

Mg-1.5Y-1.2Zn-0.44Zr alloys were newly developed as degradable metallic biomaterials. A comprehensive investigation of the microstructure, mechanical properties, in vitro degradation assessments and in vitro cytotoxicity evaluations of the as-cast state, as-heat treated state and as-extruded state alloys was done. The microstructure observations show that the Mg-1.5Y-1.2Zn-0.44Zr alloys are mainly composed of the matrix α-Mg phases and the Mg12ZnY secondary phases (LPS structure). The hot extrusion method significantly refined the grains and eliminated the defects of both as-cast and heat treated alloys and thereby contributed to the better mechanical properties and biodegradation resistance. The values of tensile strength and tensile yield strength of the alloy in the as-extruded condition are about 236 and 178 MPa respectively, with an excellent elongation of 28%. Meanwhile, the value of compressive strength is about 471 MPa and the value of bending strength is about 501 MPa. The superior bending strength further demonstrates the excellent ductility of the hot extruded alloys. The results of immersion tests and electrochemical measurements in the SBF indicate that a protective film precipitated on the alloy's surface with the extension of degradation. The protective film contains Mg(OH)2 and hydroxyapatite (HA) which can reinforce osteoblast activity and promote good biocompatibility. No significant cytotoxicity towards L-929 cells was detected and the immersion extracts of alloy samples could enhance the cell proliferation with time in the cytotoxicity evaluations, implying that the Mg-1.5Y-1.2Zn-0.44Zr alloys have the potential to be used for biomedical applications. Copyright © 2013 Elsevier B.V. All rights reserved.

Separation of uranium from (U, Th)O 2 and (U, Pu)O 2 by solid state reactions route

NASA Astrophysics Data System (ADS)

Keskar, Meera; Mudher, K. D. Singh; Venugopal, V.

2005-01-01

Solid state reactions of UO 2, ThO 2, PuO 2 and their mixed oxides (U, Th)O 2 and (U, Pu)O 2 were carried out with sodium nitrate upto 900 °C, to study the formation of various phases at different temperatures, which are amenable for easy dissolution and separation of the actinide elements in dilute acid. Products formed by reacting unsintered as well as sintered UO 2 with NaNO 3 above 500 °C were readily soluble in 2 M HNO 3, whereas ThO 2 and PuO 2 did not react with NaNO 3 to form any soluble products. Thus reactions of mixed oxides (U, Th)O 2 and (U, Pu)O 2 with NaNO 3 were carried out to study the quantitative separation of U from (U, Th)O 2 and (U, Pu)O 2. X-ray diffraction, X-ray fluorescence, thermal analysis and chemical analysis techniques were used for the characterization of the products formed during the reactions.

In vitro bio-functional performances of the novel superelastic beta-type Ti-23Nb-0.7Ta-2Zr-0.5N alloy.

PubMed

Ion, Raluca; Gordin, Doina-Margareta; Mitran, Valentina; Osiceanu, Petre; Dinescu, Sorina; Gloriant, Thierry; Cimpean, Anisoara

2014-02-01

The materials used for internal fracture fixations and joint replacements are mainly made of metals which still face problems ranging from higher rigidity than that of natural bone to leaching cytotoxic metallic ions. Beta (β)-type titanium alloys with low elastic modulus made from non-toxic and non-allergenic elements are desirable to reduce stress shielding effect and enhance bone remodeling. In this work, a new β-type Ti-23Nb-0.7Ta-2Zr-0.5N alloy with a Young's modulus of approximately 50 GPa was designed and characterized. The behavior of MC3T3-E1 pre-osteoblasts on the new alloy, including adhesion, proliferation and differentiation, was evaluated by examining the cytoskeleton, focal adhesion formation, metabolic activity and extracellular matrix mineralization. Results indicated that the pre-osteoblast cells exhibited a similar degree of attachment and growth on Ti-23Nb-0.7Ta-2Zr-0.5N and Ti-6Al-4V. However, the novel alloy proved to be significantly more efficient in sustaining mineralized matrix deposition upon osteogenic induction of the cells than Ti-6Al-4V control. Further, the analysis of RAW 264.7 macrophages cytokine gene and protein expression indicated no significant inflammatory response. Collectively, these findings suggest that the Ti-23Nb-0.7Ta-2Zr-0.5N alloy, which has an increased mechanical biocompatibility with bone, allows a better osteogenic differentiation of osteoblast precursor cells than Ti-6Al-4V and holds great potential for future clinical prosthetic applications. Copyright © 2013 Elsevier B.V. All rights reserved.

Effect of Annealing Processes on Cu-Zr Alloy Film for Copper Metallization

NASA Astrophysics Data System (ADS)

Wang, Ying; Li, Fu-yin; Tang, Bin-han

2017-12-01

The effect of two different annealing processes on the microstructure and barrier-forming ability of Cu-Zr alloy films has been investigated. Cu-Zr alloy films were deposited directly onto SiO2/Si substrates via direct current magnetron sputtering and subsequently annealed by the vacuum annealing process (VAP) or rapid annealing process under argon atmosphere at temperatures 350°C, 450°C, and 550°C. Then, the microstructure, interface characteristics, and electrical properties of the samples were measured. After annealing, the samples showed a preferential (111) crystal orientation, independent of the annealing process. After two annealing methods, Zr aggregated at the Cu-Zr/SiO2 interface and no serious interdiffusion occurred between Cu and Si. The leakage current measurements revealed that the samples annealed by VAP show a higher reliability. According to the results, the vacuum annealing has better barrier performance than the rapid annealing when used for the fabrication of Cu-based interconnects.

Mechanical Properties and Microstructure of TIG and FSW Joints of a New Al-Mg-Mn-Sc-Zr Alloy

NASA Astrophysics Data System (ADS)

Xu, Guofu; Qian, Jian; Xiao, Dan; Deng, Ying; Lu, Liying; Yin, Zhimin

2016-04-01

A new Al-5.8%Mg-0.4%Mn-0.25%Sc-0.10%Zr (wt.%) alloy was successfully welded by tungsten inert gas (TIG) and friction stir welding (FSW) techniques, respectively. The mechanical properties and microstructure of the welded joints were investigated by microhardness measurements, tensile tests, and microscopy methods. The results show that the ultimate tensile strength, yield strength, and elongation to failure are 358, 234 MPa, and 27.6% for TIG welded joint, and 376, 245 MPa and 31.9% for FSW joint, respectively, showing high strength and superior ductility. The TIG welded joint fails in the heat-affected zone and the fracture of FSW joint is located in stirred zone. Al-Mg-Mn-Sc-Zr alloy is characterized by lots of dislocation tangles and secondary coherent Al3(Sc,Zr) particles. The superior mechanical properties of the TIG and FSW joints are mainly derived from the Orowan strengthening and grain boundary strengthening caused by secondary coherent Al3(Sc,Zr) nano-particles (20-40 nm). For new Al-Mg-Mn-Sc-Zr alloy, the positive effect from secondary Al3(Sc, Zr) particles in the base metal can be better preserved in FSW joint than in TIG welded joint.

Structural Characterization of Am(III)- and Pu(III)-DOTA Complexes.

PubMed

Audras, Matthieu; Berthon, Laurence; Berthon, Claude; Guillaumont, Dominique; Dumas, Thomas; Illy, Marie-Claire; Martin, Nicolas; Zilbermann, Israel; Moiseev, Yulia; Ben-Eliyahu, Yeshayahu; Bettelheim, Armand; Cammelli, Sebastiano; Hennig, Christoph; Moisy, Philippe

2017-10-16

The complexation of 1,4,7,10-tetrazacyclodecane-1,4,7,10-tetraacetic acid (DOTA) ligand with two trivalent actinides (Am 3+ and Pu 3+ ) was investigated by UV-visible spectrophotometry, NMR spectroscopy, and extended X-ray absorption fine structure in conjunction with computational methods. The complexation process of these two cations is similar to what has been previously observed with lanthanides(III) of similar ionic radius. The complexation takes place in different steps and ends with the formation of a (1:1) complex [(An(III)DOTA)(H 2 O)] - , where the cation is bonded to the nitrogen atoms of the ring, the four carboxylate arms, and a water molecule to complete the coordination sphere. The formation of An(III)-DOTA complexes is faster than the Ln(III)-DOTA systems of equivalent ionic radius. Furthermore, it is found that An-N distances are slightly shorter than Ln-N distances. Theoretical calculations showed that the slightly higher affinity of DOTA toward Am over Nd is correlated with slightly enhanced ligand-to-metal charge donation arising from oxygen and nitrogen atoms.

Transverse-Weld Tensile Properties of a New Al-4Cu-2Si Alloy as Filler Metal

NASA Astrophysics Data System (ADS)

Sampath, K.

2009-12-01

AA2195, an Al-Cu-Li alloy in the T8P4 age-hardened condition, is a candidate aluminum armor for future combat vehicles, as this material offers higher static strength and ballistic protection than current aluminum armor alloys. However, certification of AA2195 alloy for armor applications requires initial qualification based on the ballistic performance of welded panels in the as-welded condition. Currently, combat vehicle manufacturers primarily use gas metal arc welding (GMAW) process to meet their fabrication needs. Unfortunately, a matching GMAW consumable electrode is currently not commercially available to allow effective joining of AA2195 alloy. This initial effort focused on an innovative, low-cost, low-risk approach to identify an alloy composition suitable for effective joining of AA2195 alloy, and evaluated transverse-weld tensile properties of groove butt joints produced using the identified alloy. Selected commercial off-the-shelf (COTS) aluminum alloy filler wires were twisted to form candidate twisted filler rods. Representative test weldments were produced using AA2195 alloy, candidate twisted filler rods and gas tungsten arc welding (GTAW) process. Selected GTA weldments produced using Al-4wt.%Cu-2wt.%Si alloy as filler metal consistently provided transverse-weld tensile properties in excess of 275 MPa (40 ksi) UTS and 8% El (over 25 mm gage length), thereby showing potential for acceptable ballistic performance of as-welded panels. Further developmental work is required to evaluate in detail GMAW consumable wire electrodes based on the Al-Cu-Si system containing 4.2-5.0 wt.% Cu and 1.6-2.0 wt.% Si.

AFS-2 FLOWSHEET MODIFICATIONS TO ADDRESS THE INGROWTH OF PU(VI) DURING METAL DISSOLUTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crapse, K.; Rudisill, T.; O'Rourke, P.

2014-07-02

In support of the Alternate Feed Stock Two (AFS-2) PuO{sub 2} production campaign, Savannah River National Laboratory (SRNL) conducted a series of experiments concluding that dissolving Pu metal at 95°C using a 6–10 M HNO{sub 3} solution containing 0.05–0.2 M KF and 0–2 g/L B could reduce the oxidation of Pu(IV) to Pu(VI) as compared to dissolving Pu metal under the same conditions but at or near the boiling temperature. This flowsheet was demonstrated by conducting Pu metal dissolutions at 95°C to ensure that PuO{sub 2} solids were not formed during the dissolution. These dissolution parameters can be used formore » dissolving both Aqueous Polishing (AP) and MOX Process (MP) specification materials. Preceding the studies reported herein, two batches of Pu metal were dissolved in the H-Canyon 6.1D dissolver to prepare feed solution for the AFS-2 PuO{sub 2} production campaign. While in storage, UV-visible spectra obtained from an at-line spectrophotometer indicated the presence of Pu(VI). Analysis of the solutions also showed the presence of Fe, Ni, and Cr. Oxidation of Pu(IV) produced during metal dissolution to Pu(VI) is a concern for anion exchange purification. Anion exchange requires Pu in the +4 oxidation state for formation of the anionic plutonium(IV) hexanitrato complex which absorbs onto the resin. The presence of Pu(VI) in the anion feed solution would require a valence adjustment step to prevent losses. In addition, the presence of Cr(VI) would result in absorption of chromate ion onto the resin and could limit the purification of Pu from Cr which may challenge the purity specification of the final PuO{sub 2} product. Initial experiments were performed to quantify the rate of oxidation of Pu(IV) to Pu(VI) (presumed to be facilitated by Cr(VI)) as functions of the HNO{sub 3} concentration and temperature in simulated dissolution solutions containing Cr, Fe, and Ni. In these simulated Pu dissolutions studies, lowering the temperature from near

Pre-Licensing Evaluation of Legacy SFR Metallic Fuel Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yacout, A. M.; Billone, M. C.

2016-09-16

The US sodium cooled fast reactor (SFR) metallic fuel performance data that are of interest to advanced fast reactors applications, can be attributed mostly to the Integral Fast Reactor (IFR) program between 1984 and 1994. Metallic fuel data collected prior to the IFR program were associated with types of fuel that are not of interest to future advanced reactors deployment (e.g., previous U-Fissium alloy fuel). The IFR fuels data were collected from irradiation of U-Zr based fuel alloy, with and without Pu additions, and clad in different types of steels, including HT9, D9, and 316 stainless-steel. Different types of datamore » were generated during the program, and were based on the requirements associated with the DOE Advanced Liquid Metal Cooled Reactor (ALMR) program.« less

Wear Resistance Enhancement of Ti-6Al-4 V Alloy by Applying Zr-Modified Silicide Coatings

NASA Astrophysics Data System (ADS)

Li, Xuan; Hu, Guangzhong; Tian, Jin; Tian, Wei; Xie, Wenling; Li, Xiulan

2018-03-01

Zr-modified silicide coatings were prepared on Ti-6Al-4 V alloy by pack cementation process to enhance its wear resistance. The microstructure and wear properties of the substrate and the coatings were comparatively investigated using GCr15 and Al2O3 as the counterparts under different sliding loads. The obtained Zr-modified silicide coating had a multilayer structure, consisting of a thick (Ti, X)Si2 (X represents Al, Zr and V elements) outer layer, a TiSi middle layer and a Ti5Si4 + Ti5Si3 inner layer. The micro-hardness of the coating was much higher than the substrate and displayed a decrease tendency from the coating surface to the interior. Sliding against either GCr15 or Al2O3 balls, the coatings showed superior anti-friction property to the Ti-6Al-4 V alloy, as confirmed by its much lower wear rate under each employed sliding condition.

Biocompatible Ni-free Zr-based bulk metallic glasses with high-Zr-content: compositional optimization for potential biomedical applications.

PubMed

Hua, Nengbin; Huang, Lu; Chen, Wenzhe; He, Wei; Zhang, Tao

2014-11-01

The present study designs and prepares Ni-free Zr60+xTi2.5Al10Fe12.5-xCu10Ag5 (at.%, x=0, 2.5, 5) bulk metallic glasses (BMGs) by copper mold casting for potential biomedical application. The effects of Zr content on the in vitro biocompatibility of the Zr-based BMGs are evaluated by investigating mechanical properties, bio-corrosion behavior, and cellular responses. It is found that increasing the content of Zr is favorable for the mechanical compatibility with a combination of low Young's modulus, large plasticity, and high notch toughness. Electrochemical measurements demonstrate that the Zr-based BMGs are corrosion resistant in a phosphate buffered saline solution. The bio-corrosion resistance of BMGs is improved with the increase in Zr content, which is attributed to the enrichment in Zr and decrease in Al concentration in the surface passive film of alloys. Regular cell responses of mouse MC3T3-E1 cells, including cell adhesion and proliferation, are observed on the Zr-Ti-Al-Fe-Cu-Ag BMGs, which reveals their general biosafety. The high-Zr-based BMGs exhibit a higher cell proliferation activity in comparison with that of pure Zr and Ti-6Al-4V alloy. The effects of Zr content on the in vitro biocompatibility can be used to guide the future design of biocompatible Zr-based BMGs. Copyright © 2014 Elsevier B.V. All rights reserved.

Humic acids facilitated microbial reduction of polymeric Pu(IV) under anaerobic conditions.

PubMed

Xie, Jinchuan; Liang, Wei; Lin, Jianfeng; Zhou, Xiaohua; Li, Mei

2018-01-01

Flavins and humic substances have been extensively studied with emphasis on their ability to transfer extracellular electrons to insoluble metal oxides. Nevertheless, whether the low-solubility Pu(IV) polymers are microbially reduced to aqueous Pu(III) remains uncertain. Experiments were conducted under anaerobic and slightly alkaline conditions to study the difference between humic acids and flavins to transport extracellular electrons to Pu(IV) polymers. Our study demonstrates that Shewanella putrefaciens was unable to directly reduce polymeric Pu(IV) with a notably low reduction rate (3.4×10 -12 mol/L Pu(III) aq within 144h). The relatively high redox potential of flavins reveals the thermodynamically unfavorable reduction: E h (PuO 2 (am)/Pu 3+ )2 )≈E h o '(RBF/RBFH 2 )≈-220mV at pH7.2. The microbially reduced humic acids facilitated the extracellular electron transfer to the polymers and reduced polymeric Pu(IV) (2.1×10 -10 mol/L Pu(III) aq ) 62 times more rapidly than the flavins. The driving force for electron transfer explains the observed reduction: E h (HA ox /HA red )PuO 2 (am)/Pu 3+ ) when S. putrefaciens oxidized lactate and respired on the humic acids. In contrast, flavins were able to substantially reduce aqueous Pu(IV)-EDTA (1.9×10 -9 mol/L Pu(III) aq ) because of the available driving force for electron transfer: Δ r G m =-F[E h (PuL 2 4- /PuL 2 5- )-E h o '(FMN/FMNH 2 )]=-33.5kJ/mol is a result of E h (PuL 2 4- /PuL 2 5- )≫E h (PuO 2 (am)/Pu 3+ ), where L is the EDTA ligand. In the presence of humic acids, the reduction of Pu(IV)-EDTA exhibited the most rapid rate (2.2×10 -9 mol/L Pu(III) aq ). This result further demonstrates that humic acids facilitated the extracellular electron transfer to polymeric and aqueous Pu(IV). Reductive solubilization of the polymers may enhance Pu mobility in the geosphere and hence increases risks to human health. Copyright © 2017 Elsevier B.V. All rights reserved.

Kinetics of Glass Transition and Crystallization of a Zr40Hf10Ti4Y1Al10Cu25Ni7Co2Fe1 Bulk Metallic Glass with High Mixing Entropy

NASA Astrophysics Data System (ADS)

Gong, Pan; Wang, Sibo; Li, Fangwei; Wang, Xinyun

2018-04-01

The kinetics of glass transition and crystallization of a novel Zr40Hf10Ti4Y1Al10Cu25Ni7Co2Fe1 bulk metallic glass (BMG) with high mixing entropy have been studied by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The continuous DSC curves show five stages of crystallization at lower heating rates (≤ 20 K/min). The activation energies of glass transition were determined by Moynihan and Kissinger methods, while the activation energies of crystallization were calculated utilizing Kissinger, Ozawa, and Boswell models. The crystalline phases corresponding to each crystallization step have been found out. The kinetic fragility of Zr40Hf10Ti4Y1Al10Cu25Ni7Co2Fe1 BMG has also been evaluated. Based on the isothermal DSC curves, the Avrami exponent, evaluated from the Johnson-Mehl-Avrami equation, has been analyzed in detail. The current study reveals that the crystallization behavior of Zr40Hf10Ti4Y1Al10Cu25Ni7Co2Fe1 BMG exhibits characteristics of both the high entropy BMGs and traditional BMGs with a single principal element, leading to its high glass-forming ability.

Metallic glass alloys of Zr, Ti, Cu and Ni

DOEpatents

Lin, X.; Peker, A.; Johnson, W.L.

1997-04-08

At least quaternary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10{sup 3} K/s. Such alloys comprise titanium from 19 to 41 atomic percent, an early transition metal (ETM) from 4 to 21 atomic percent and copper plus a late transition metal (LTM) from 49 to 64 atomic percent. The ETM comprises zirconium and/or hafnium. The LTM comprises cobalt and/or nickel. The composition is further constrained such that the product of the copper plus LTM times the atomic proportion of LTM relative to the copper is from 2 to 14. The atomic percentage of ETM is less than 10 when the atomic percentage of titanium is as high as 41, and may be as large as 21 when the atomic percentage of titanium is as low as 24. Furthermore, when the total of copper and LTM are low, the amount of LTM present must be further limited. Another group of glass forming alloys has the formula (ETM{sub 1{minus}x}Ti{sub x}){sub a} Cu{sub b} (Ni{sub 1{minus}y}Co{sub y}){sub c} wherein x is from 0.1 to 0.3, y{center_dot}c is from 0 to 18, a is from 47 to 67, b is from 8 to 42, and c is from 4 to 37. This definition of the alloys has additional constraints on the range of copper content, b. 2 figs.

Effect of annealing temperature on microstructure and superelastic properties of a Ti-18Zr-4.5Nb-3Sn-2Mo alloy.

PubMed

Fu, Jie; Kim, Hee Young; Miyazaki, Shuichi

2017-01-01

In this study a new superelastic Ti-18Zr-4.5Nb-3Sn-2Mo alloy was prepared by adding 2at% of Mo as a substitute for Nb to the Ti-18Zr-11Nb-3Sn alloy, and heat treatment at different temperatures was conducted. The temperature dependence of superelasticity and annealing texture was investigated. Texture showed a dependence of annealing temperature: the specimen annealed at 923K for 0.3ks exhibited {113} β <47¯1> β type texture which was similar to the deformation texture, while specimens annealed at 973, 1073K, and 1173K showed {001} β <110> β type recrystallization texture which was preferable for recovery strain. The largest recovery strain of 6.2%, which is the same level as that of the Ti-18Zr-11Nb-3Sn alloy, was obtained in the specimen annealed at 1173K for 0.3ks due to the well-developed {001} β <110> β type recrystallization texture. The Ti-18Zr-3Nb-3Sn-2Mo alloy presented a higher tensile strength compared with the Ti-18Zr-11Nb-3Sn alloy when heat treated at 1173K for 0.3ks, which was due to the solid solution strengthening effect of Mo. Annealing at 923K for 0.3ks was effective in obtaining a good combination of a high strength as 865MPa and a large recovery strain as 5.6%. The high recovery strain was due to the high stress at which the maximum recovery stain was obtained which was attributed to the small grain size formed at low annealing temperature. Copyright © 2016 Elsevier Ltd. All rights reserved.

AlGaN/GaN High Electron Mobility Transistor Grown and Fabricated on ZrTi Metallic Alloy Buffer Layers

DOE PAGES

Ren, Fan; Pearton, Stephen J.; Ahn, Shihyun; ...

2017-09-26

AlGaN/GaN high electron mobility transistors (HEMTs) were demonstrated for structures grown on ZrTi metallic alloy buffer layers, which provided lattice matching of the in-plane lattice parameter (“a-parameter”) to hexagonal GaN. The quality of the GaN buffer layer and HEMT structure were confirmed with X-ray 2θ and rocking scans as well as cross-section transmission electron microscopy (TEM) images. The X-ray 2θ scans showed full widths at half maximum (FWHM) of 0.06°, 0.05° and 0.08° for ZrTi alloy, GaN buffer layer, and the entire HEMT structure, respectively. TEM of the lower section of the HEMT structure containing the GaN buffer layer andmore » the AlN/ZrTi/AlN stack on the Si substrate showed that it was important to grow AlN on the top of ZrTi prior to growing the GaN buffer layer. Finally, the estimated threading dislocation (TD) density in the GaN channel layer of the HEMT structure was in the 10 8 cm -2 range.« less

Crystal Nucleation and Growth in Undercooled Melts of Pure Zr, Binary Zr-Based and Ternary Zr-Ni-Cu Glass-Forming Alloys

NASA Astrophysics Data System (ADS)

Herlach, Dieter M.; Kobold, Raphael; Klein, Stefan

2018-03-01

Glass formation of a liquid undercooled below its melting temperature requires the complete avoidance of crystal nucleation and subsequent crystal growth. Even though they are not part of the glass formation process, a detailed knowledge of both processes involved in crystallization is mandatory to determine the glass-forming ability of metals and metallic alloys. In the present work, methods of containerless processing of drops by electrostatic and electromagnetic levitation are applied to undercool metallic melts prior to solidification. Heterogeneous nucleation on crucible walls is completely avoided giving access to large undercoolings. A freely suspended drop offers the additional benefit of showing the rapid crystallization process of an undercooled melt in situ by proper diagnostic means. As a reference, crystal nucleation and dendrite growth in the undercooled melt of pure Zr are experimentally investigated. Equivalently, binary Zr-Cu, Zr-Ni and Zr-Pd and ternary Zr-Ni-Cu alloys are studied, whose glass-forming abilities differ. The experimental results are analyzed within classical nucleation theory and models of dendrite growth. The findings give detailed knowledge about the nucleation-undercooling statistics and the growth kinetics over a large range of undercooling.

Ca(5)Zr(3)F(22).

PubMed

Oudahmane, Abdelghani; El-Ghozzi, Malika; Avignant, Daniel

2012-04-01

Single crystals of Ca(5)Zr(3)F(22), penta-calcium trizirconium docosafluoride, were obtained unexpectedly by solid-state reaction between CaF(2) and ZrF(4) in the presence of AgF. The structure of the title compound is isotypic with that of Sr(5)Zr(3)F(22) and can be described as being composed of layers with composition [Zr(3)F(20)](8-) made up from two different [ZrF(8)](4-) square anti-prisms (one with site symmetry 2) by corner-sharing. The layers extending parallel to the (001) plane are further linked by Ca(2+) cations, forming a three-dimensional network. Amongst the four crystallographically different Ca(2+) ions, three are located on twofold rotation axes. The Ca(2+) ions exhibit coordination numbers ranging from 8 to 12, depending on the cut off, with very distorted fluorine environments. Two of the Ca(2+) ions occupy inter-stices between the layers whereas the other two are located in void spaces of the [Zr(3)F(20)](8-) layer and alternate with the two Zr atoms along [010]. The crystal under investigation was an inversion twin.

Effects of Zr alloying on the microstructure and magnetic properties of Alnico permanent magnets

NASA Astrophysics Data System (ADS)

Rehman, Sajjad Ur; Ahmad, Zubair; Haq, A. ul; Akhtar, Saleem

2017-11-01

Alnico-8 permanent magnets were produced through casting and subsequent thermal treatment process. Magnetic alloy of nominal composition 32.5 Fe-7.5 Al-1.0 Nb-35.0 Co-4.0 Cu-14.0 Ni-6.0 Ti were prepared by arc melting and casting technique. The Zr was added to 32.5 Fe-7.5 Al-1.0 Nb-35.0 Co-4.0 Cu-14.0 Ni-6.0 Ti alloy ranging from 0.3 to 0.9 wt%. The magnets were developed by employing two different heat treatment cycles known as conventional treatment and thermo-magnetic annealing treatment. The samples were characterized by X-ray diffraction method, Scanning electron microscope and magnetometer by plotting magnetic hysteresis demagnetization curves. The results indicate that magnetic properties are strongly depended upon alloy chemistry and process. The 0.6 wt% Zr added alloys yielded the best magnetic properties among the studied alloys. The magnetic properties obtained through conventional heat treatment are Hc = 1.35 kOe, Br = 5.2 kG and (BH)max = 2 MGOe. These magnetic properties were enhanced to Hc = 1.64 kOe, Br = 6.3 kG and (BH)max = 3.7 MGOe by thermo-magnetic annealing treatment.

Temporal evolution of 137Cs, 237Np, and 239+240Pu and estimated vertical 239+240Pu export in the northwestern Mediterranean Sea.

PubMed

Bressac, M; Levy, I; Chamizo, E; La Rosa, J J; Povinec, P P; Gastaud, J; Oregioni, B

2017-10-01

The evolution of 137 Cs, 237 Np and 239+240 Pu at the DYFAMED station (NW Mediterranean) is discussed in relation to physical processes, downward fluxes of particles, and changes in the main input sources. The data set presented in this study represents the first complete 237 Np vertical profiles (0.12-0.27μBqL -1 ), and constitutes a baseline measurement to assess future changes. A similar behavior of Cs and Np has been evidenced, confirming that Np behaves conservatively. While the 137 Cs decrease has been driven by its radioactive decay, the vertical distribution of 237 Np has not substantially changed over the last decade. In the absence of recent major inputs, a homogenization of their vertical distribution occurred, partly due to deep convection events that became more intense during the last decade. In contrast, 239+240 Pu surface levels in the NW Mediterranean waters have fallen in the past four decades by a factor of 5. This decrease in surface has been balanced by higher concentrations in the deep-water layers. A first estimate of the downward 239+240 Pu fluxes in the NW Mediterranean Sea is proposed over more than two decades. This estimation, based on the DYFAMED sediment trap time-series data and published 239+240 Pu flux measurements, suggests that sinking particles have accounted for 60-90% of the upper layer (0-200m) Pu inventory loss over the period 1989-2013. The upper layer residence time of Pu is estimated to be ~28years, twice as long as the residence time estimated for the whole western Mediterranean (~15years). This difference highlights the slow removal of Pu in the open waters of the NW Mediterranean and confirms that most of the Pu removal occurs along the coastal margin where sedimentation rates are high. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrical resistance oscillations during plastic deformation in A Ti-Al-Nb-Zr alloy at 4·2 K

NASA Astrophysics Data System (ADS)

Nikiforenko, V. N.; Lavrentev, F. F.

1986-10-01

The serrated plastic flow in titanium alloy containing 5% Al, 2·5% Zr and 2% Nb has been investigated by measuring its electrical resistance and applying selective chemical etching. The electrical resistance was found to oscillate under active deformation at 4·2 K. Analysis of the possible causes seems to indicate a dominant role of break by dislocation pile-ups through obstacles, viz second phase precipitates and grain boundaries.

Analysis of plutonium isotope ratios including 238Pu/239Pu in individual U-Pu mixed oxide particles by means of a combination of alpha spectrometry and ICP-MS.

PubMed

Esaka, Fumitaka; Yasuda, Kenichiro; Suzuki, Daisuke; Miyamoto, Yutaka; Magara, Masaaki

2017-04-01

Isotope ratio analysis of individual uranium-plutonium (U-Pu) mixed oxide particles contained within environmental samples taken from nuclear facilities is proving to be increasingly important in the field of nuclear safeguards. However, isobaric interferences, such as 238 U with 238 Pu and 241 Am with 241 Pu, make it difficult to determine plutonium isotope ratios in mass spectrometric measurements. In the present study, the isotope ratios of 238 Pu/ 239 Pu, 240 Pu/ 239 Pu, 241 Pu/ 239 Pu, and 242 Pu/ 239 Pu were measured for individual Pu and U-Pu mixed oxide particles by a combination of alpha spectrometry and inductively coupled plasma mass spectrometry (ICP-MS). As a consequence, we were able to determine the 240 Pu/ 239 Pu, 241 Pu/ 239 Pu, and 242 Pu/ 239 Pu isotope ratios with ICP-MS after particle dissolution and chemical separation of plutonium with UTEVA resins. Furthermore, 238 Pu/ 239 Pu isotope ratios were able to be calculated by using both the 238 Pu/( 239 Pu+ 240 Pu) activity ratios that had been measured through alpha spectrometry and the 240 Pu/ 239 Pu isotope ratios determined through ICP-MS. Therefore, the combined use of alpha spectrometry and ICP-MS is useful in determining plutonium isotope ratios, including 238 Pu/ 239 Pu, in individual U-Pu mixed oxide particles. Copyright © 2016 Elsevier B.V. All rights reserved.

A new Mantle Source Tapped During Episode 55 of the Pu'u O'o Eruption From Kilauea Volcano

NASA Astrophysics Data System (ADS)

Marske, J. P.; Pietruszka, A. J.; Garcia, M. O.; Rhodes, J. M.

2005-12-01

Over 22 years of continuous geochemical monitoring of lavas from the current Pu'u O'o eruption allows us to probe the mantle and crustal processes beneath Kilauea Volcano in unparalleled detail. Episode 55 (1997-present) marks the longest and most voluminous Pu'u O'o eruptive interval. Here we present new Pb, Sr, and Nd isotopic ratios and major- and trace-element abundances for the most recent lavas (1999-2005). MgO variation diagrams show that most of the major-element variations are related to olivine fractionation. However, Pu'u O'o lavas display longer-term systematic decreases in their TiO2, K2O, P2O5 and CaO abundances (at a given MgO) due to changes in the parental magma composition. Incompatible element ratios (K2O/TiO2, Nb/Y, Nb/Zr) and MgO-normalized abundances (Sr, Rb, K) in episode 55 lavas delimit the lowest values observed during the Pu'u O'o eruption. Earlier Pu'u O'o lavas displayed a temporal decrease in highly over moderately incompatible trace-element ratios, near constant SiO2 contents, and a gradual increase in 87Sr/86Sr. However, episode 55 lavas (between days 5500-6500) record an increase in MgO-normalized SiO2 contents and even higher 87Sr/86Sr with near constant incompatible trace-element ratios. Neither a single mantle source composition nor a change in partial melting conditions can explain these observations. Based on 226Ra-230Th-238U disequilibria and partial melting modeling of trace elements, we conclude that Pu'u O'o lavas originate from at least two distinct mantle source components: (1) a recently depleted component that was subsequently remelted to explain the overall decreases of incompatible major- and trace-element ratios and abundances, and (2) a compositionally and isotopically distinct mantle component that was not previously melted within the Hawaiian plume to explain the temporal increase in 87Sr/86Sr and SiO2 abundances and the flattening trend of incompatible trace-element ratios. This second component lies within

The Mechanical Properties and In Vitro Biocompatibility of PM-Fabricated Ti-28Nb-35.4Zr Alloy for Orthopedic Implant Applications

PubMed Central

Xu, Wei; Li, Ming; Wen, Cuie; Lv, Shaomin; Liu, Chengcheng; Lu, Xin

2018-01-01

A biocompatible Ti-28Nb-35.4Zr alloy used as bone implant was fabricated through the powder metallurgy process. The effects of mechanical milling and sintering temperatures on the microstructure and mechanical properties were investigated systematically, before in vitro biocompatibility of full dense Ti-28Nb-35.4Zr alloy was evaluated by cytotoxicity tests. The results show that the mechanical milling and sintering temperatures have significantly effects on the density and mechanical properties of the alloys. The relative density of the alloy fabricated by the atomized powders at 1500 °C is only 83 ± 1.8%, while the relative density of the alloy fabricated by the ball-milled powders can rapidly reach at 96.4 ± 1.3% at 1500 °C. When the temperature was increased to 1550 °C, the alloy fabricated by ball-milled powders achieve full density (relative density is 98.1 ± 1.2%). The PM-fabricated Ti-28Nb-35.4Zr alloy by ball-milled powders at 1550 °C can achieve a wide range of mechanical properties, with a compressive yield strength of 1058 ± 35.1 MPa, elastic modulus of 50.8 ± 3.9 GPa, and hardness of 65.8 ± 1.5 HRA. The in vitro cytotoxicity test suggests that the PM-fabricated Ti-28Nb-35.4Zr alloy by ball-milled powders at 1550 °C has no adverse effects on MC3T3-E1 cells with cytotoxicity ranking of 0 grade, which is nearly close to ELI Ti-6Al-4V or CP Ti. These properties and the net-shape manufacturability makes PM-fabricated Ti-28Nb-35.4Zr alloy a low-cost, highly-biocompatible, Ti-based biomedical alloy. PMID:29601517

The Mechanical Properties and In Vitro Biocompatibility of PM-Fabricated Ti-28Nb-35.4Zr Alloy for Orthopedic Implant Applications.

PubMed

Xu, Wei; Li, Ming; Wen, Cuie; Lv, Shaomin; Liu, Chengcheng; Lu, Xin; Qu, Xuanhui

2018-03-30

A biocompatible Ti-28Nb-35.4Zr alloy used as bone implant was fabricated through the powder metallurgy process. The effects of mechanical milling and sintering temperatures on the microstructure and mechanical properties were investigated systematically, before in vitro biocompatibility of full dense Ti-28Nb-35.4Zr alloy was evaluated by cytotoxicity tests. The results show that the mechanical milling and sintering temperatures have significantly effects on the density and mechanical properties of the alloys. The relative density of the alloy fabricated by the atomized powders at 1500 °C is only 83 ± 1.8%, while the relative density of the alloy fabricated by the ball-milled powders can rapidly reach at 96.4 ± 1.3% at 1500 °C. When the temperature was increased to 1550 °C, the alloy fabricated by ball-milled powders achieve full density (relative density is 98.1 ± 1.2%). The PM-fabricated Ti-28Nb-35.4Zr alloy by ball-milled powders at 1550 °C can achieve a wide range of mechanical properties, with a compressive yield strength of 1058 ± 35.1 MPa, elastic modulus of 50.8 ± 3.9 GPa, and hardness of 65.8 ± 1.5 HRA. The in vitro cytotoxicity test suggests that the PM-fabricated Ti-28Nb-35.4Zr alloy by ball-milled powders at 1550 °C has no adverse effects on MC3T3-E1 cells with cytotoxicity ranking of 0 grade, which is nearly close to ELI Ti-6Al-4V or CP Ti. These properties and the net-shape manufacturability makes PM-fabricated Ti-28Nb-35.4Zr alloy a low-cost, highly-biocompatible, Ti-based biomedical alloy.

Zr-based bulk metallic glass as a cylinder material for high pressure apparatuses

DOE PAGES

Komatsu, Kazuki; Munakata, Koji; Matsubayashi, Kazuyuki; ...

2015-05-12

Zirconium-based bulk metallic glass (Zr-based BMG) has outstanding properties as a cylinder mate- rial for piston-cylinder high pressure apparatuses and is especially useful for neutron scattering. The piston-cylinder consisting of a Zr-based BMG cylinder with outer/inner diameters of 8.8/2.5 mm sustains pressures up to 1.81 GPa and ruptured at 2.0 GPa, with pressure values determined by the superconduct- ing temperature of lead. The neutron attenuation of Zr-based BMG is similar to that of TiZr null-scattering alloy and more transparent than that of CuBe alloy. No contamination of sharp Bragg reflections is observed in the neutron diffraction pattern for Zr-based BMG.more » The magnetic susceptibility of Zr-based BMG is similar to that of CuBe alloy; this leads to a potential application for measurements of magnetic properties under pressure.« less

Ti12.5Zr21V10Cr8.5MnxCo1.5Ni46.5-x AB2-type metal hydride alloys for electrochemical storage application: Part 1. Structural characteristics

NASA Astrophysics Data System (ADS)

Bendersky, L. A.; Wang, K.; Levin, I.; Newbury, D.; Young, K.; Chao, B.; Creuziger, A.

2012-11-01

The microstructures of a series of AB2-based metal hydride alloys (Ti12.5Zr21V10Cr8.5MnxCo1.5Ni46.5-x) designed to have different fractions of non-Laves secondary phases were studied by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectrometry, and electron backscatter diffraction. The results indicate that the alloys contain a majority of hydrogen storage Laves phases and a minority of fine-structured non-Laves phases. Formation of the phases is accomplished by dendritic growth of a hexagonal C14 Laves phase. The C14 phase is followed by either a peritectic solidification of a cubic C15 Laves phase (low Mn containing alloys) or a C14 phase of different composition (high Mn containing alloys), and finally a B2 phase formed in the interdendritic regions (IDR). The interdendritic regions may then undergo further solid-state transformation into Zr7Ni10-type, Zr9Ni11-type and TiNi-type phases. As the Mn content in the alloy increases, the fraction of the C14 phase increases, whereas the fraction of C15 decreases. In the IDRs when the alloy's Mn content increases the Zr9Ni11 phases and Zr7Ni10 phase fraction first increases and then decreases, while the TiNi-based phase fraction first increases and then stabilized at 0.02. IDR compositions can be generally expressed as (Ti,Zr,V,Cr,Mn,Co)50Ni50, which accounted for 7-10% of the overall alloy volume fraction.

Microstructural Evolution of the Interface Between Pure Titanium and Low Melting Point Zr-Ti-Ni(Cu) Filler Metals

NASA Astrophysics Data System (ADS)

Lee, Dongmyoung; Sun, Juhyun; Kang, Donghan; Shin, Seungyoung; Hong, Juhwa

2014-12-01

Low melting point Zr-based filler metals with melting point depressants (MPDs) such as Cu and Ni elements are used for titanium brazing. However, the phase transition of the filler metals in the titanium joint needs to be explained, since the main element of Zr in the filler metals differs from that of the parent titanium alloys. In addition, since the MPDs easily form brittle intermetallics, that deteriorate joint properties, the phase evolution they cause needs to be studied. Zr-based filler metals having Cu content from 0 to 12 at. pct and Ni content from 12 to 24 at. pct with a melting temperature range of 1062 K to 1082 K (789 °C to 809 °C) were wetting-tested on a titanium plate to investigate the phase transformation and evolution at the interface between the titanium plate and the filler metals. In the interface, the alloys system with Zr, Zr2Ni, and (Ti,Zr)2Ni phases was easily changed to a Ti-based alloy system with Ti, Ti2Ni, and (Ti,Zr)2Ni phases, by the local melting of parent titanium. The dissolution depths of the parent metal were increased with increasing Ni content in the filler metals because Ni has a faster diffusion rate than Cu. Instead, slow diffusion of Cu into titanium substrate leads to the accumulation of Cu at the molten zone of the interface, which could form undesirable Ti x Cu y intermetallics. This study confirmed that Zr-based filler metals are compatible with the parent titanium metal with the minimum content of MPDs.

Corrosion behavior and oxide properties of Zr 1.1 wt%Nb 0.05 wt%Cu alloy

NASA Astrophysics Data System (ADS)

Park, Jeong-Yong; Choi, Byung-Kwon; Yoo, Seung Jo; Jeong, Yong Hwan

2006-12-01

The corrosion behavior and oxide properties of Zr-1.1 wt%Nb-0.05 wt%Cu (ZrNbCu) and Zircaloy-4 have been investigated. The corrosion rate of the ZrNbCu alloy was much lower than that of the Zirclaoy-4 in the 360 °C water and 360 °C PWR-simulating loop condition without a neutron flux and it was increased with an increase of the final annealing temperature from 470 °C to 570 °C. TEM observations revealed that the precipitates in the ZrNbCu were β-Nb and ZrNbFe-precipitate with β-Nb being more frequently observed and that the precipitates were more finely distributed in the ZrNbCu alloy. It was also observed that the oxides of the ZrNbCu and Zircaloy-4 consisted of two and seven layers, respectively, after 1000 days in the PWR-simulating loop condition and that the thickness of a fully-developed layer was higher in the ZrNbCu than in the Zircaloy-4. It was also found that the β-Nb in ZrNbCu was oxidized more slowly when compared to the Zr(Fe, Cr) 2 in Zirclaoy-4 when the precipitates in the oxide were observed by TEM. Cracks were observed in the vicinity of the oxidized Zr(Fe, Cr) 2, while no cracks were formed near β-Nb which had retained a metallic state. From the results obtained, it is suggested that the oxide formed on the ZrNbCu has a more protective nature against a corrosion when compared to that of the Zircaloy-4.

Metallic glass alloys of Zr, Ti, Cu and Ni

DOEpatents

Lin, Xianghong; Peker, Atakan; Johnson, William L.

1997-01-01

At least quaternary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10.sup.3 K/s. Such alloys comprise titanium from 19 to 41 atomic percent, an early transition metal (ETM) from 4 to 21 atomic percent and copper plus a late transition metal (LTM) from 49 to 64 atomic percent. The ETM comprises zirconium and/or hafnium. The LTM comprises cobalt and/or nickel. The composition is further constrained such that the product of the copper plus LTM times the atomic proportion of LTM relative to the copper is from 2 to 14. The atomic percentage of ETM is less than 10 when the atomic percentage of titanium is as high as 41, and may be as large as 21 when the atomic percentage of titanium is as low as 24. Furthermore, when the total of copper and LTM are low, the amount of LTM present must be further limited. Another group of glass forming alloys has the formula (ETM.sub.1-x Ti.sub.x).sub.a Cu.sub.b (Ni.sub.1-y Co.sub.y).sub.c wherein x is from 0.1 to 0.3, y.cndot.c is from 0 to 18, a is from 47 to 67, b is from 8 to 42, and c is from 4 to 37. This definition of the alloys has additional constraints on the range of copper content, b.

Corrosion-Resistant Ti- xNb- xZr Alloys for Nitric Acid Applications in Spent Nuclear Fuel Reprocessing Plants

NASA Astrophysics Data System (ADS)

Manivasagam, Geetha; Anbarasan, V.; Kamachi Mudali, U.; Raj, Baldev

2011-09-01

This article reports the development, microstructure, and corrosion behavior of two new alloys such as Ti-4Nb-4Zr and Ti-2Nb-2Zr in boiling nitric acid environment. The corrosion test was carried out in the liquid, vapor, and condensate phases of 11.5 M nitric acid, and the potentiodynamic anodic polarization studies were performed at room temperature for both alloys. The samples subjected to three-phase corrosion testing were characterized using scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDAX). As Ti-2Nb-2Zr alloy exhibited inferior corrosion behavior in comparison to Ti-4Nb-4Zr in all three phases, weldability and heat treatment studies were carried out only on Ti-4Nb-4Zr alloy. The weldability of the new alloy was evaluated using tungsten inert gas (TIG) welding processes, and the welded specimen was thereafter tested for its corrosion behavior in all three phases. The results of the present investigation revealed that the newly developed near alpha Ti-4Nb-4Zr alloy possessed superior corrosion resistance in all three phases and excellent weldability compared to conventional alloys used for nitric acid application in spent nuclear reprocessing plants. Further, the corrosion resistance of the beta heat-treated Ti-4Nb-4Zr alloy was superior when compared to the sample heat treated in the alpha + beta phase.

Mechanism of abnormally slow crystal growth of CuZr alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, X. Q.; Lü, Y. J., E-mail: yongjunlv@bit.edu.cn; State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027

2015-10-28

Crystal growth of the glass-forming CuZr alloy is shown to be abnormally slow, which suggests a new method to identify the good glass-forming alloys. The crystal growth of elemental Cu, Pd and binary NiAl, CuZr alloys is systematically studied with the aid of molecular dynamics simulations. The temperature dependence of the growth velocity indicates the different growth mechanisms between the elemental and the alloy systems. The high-speed growth featuring the elemental metals is dominated by the non-activated collision between liquid-like atoms and interface, and the low-speed growth for NiAl and CuZr is determined by the diffusion across the interface. Wemore » find that, in contrast to Cu, Pd, and NiAl, a strong stress layering arisen from the density and the local order layering forms in front of the liquid-crystal interface of CuZr alloy, which causes a slow diffusion zone. The formation of the slow diffusion zone suppresses the interface moving, resulting in much small growth velocity of CuZr alloy. We provide a direct evidence of this explanation by applying the compressive stress normal to the interface. The compression is shown to boost the stress layering in CuZr significantly, correspondingly enhancing the slow diffusion zone, and eventually slowing down the crystal growth of CuZr alloy immediately. In contrast, the growth of Cu, Pd, and NiAl is increased by the compression because the low diffusion zones in them are never well developed.« less

Transfer of aged 239+240Pu, 238Pu, 241Am, and 137Cs to cattle grazing a contaminated arid environment.

PubMed

Gilbert, R O; Engel, D W; Anspaugh, L R

1989-09-01

In this paper, estimates are obtained of the fraction of ingested 239+240Pu, 238Pu, 241Am and 137Cs transferred to blood, muscle, liver, kidney, femur, vertebra, and gonads of a reproducing herd of 17 beef cattle, individuals of which grazed within fenced enclosures for up to 1064 days under natural conditions with no supplemental feeding at an arid site contaminated 16 years previously with transuranic radionuclides. The estimated geometric mean (GM) GI-to-blood fractional transfer of 238Pu (0.0001) was about 20 times larger than the estimated transfer of 239+240Pu (0.000005), while the estimated transfer of 241Am (0.00001) was about 2 times larger than that of 239+240Pu. These GM GI-to-blood transfers were smaller than the GI-to-blood transfer value of 0.001 recommended by the International Commission on Radiological Protection (ICRP) for humans exposed via food chains or occupationally from unknown mixtures or compounds of plutonium and americium. Statistical tests indicated significantly (p less than 0.05) larger GI-to-tissue transfers of (1) 238Pu as compared to 239+240Pu for all tissues examined, (2) of 238Pu as compared to 241Am for muscle, liver, femur, and vertebra, and (3) of 241Am as compared to 239+240Pu for blood serum, femur, and kidney. The estimated GM fractional transfers of 137Cs from GI to muscle and liver were 0.03 (n = 8) and 0.001 (n = 3), respectively, assuming a 50-day biological half-time of 137Cs in cattle tissue.

Supercritical fluid extraction and separation of uranium from other actinides.

PubMed

Quach, Donna L; Mincher, Bruce J; Wai, Chien M

2014-06-15

The feasibility of separating U from nitric acid solutions of mixed actinides using tri-n-butylphosphate (TBP)-modified supercritical fluid carbon dioxide (sc-CO2) was investigated. The actinides U, Np, Pu, and Am were extracted into sc-CO2 modified with TBP from a range of nitric acid concentrations, in the absence of, or in the presence of, a number of traditional reducing and/or complexing agents to demonstrate the separation of these metals from U under sc-CO2 conditions. The separation of U from Pu using sc-CO2 was successful at nitric acid concentrations of less than 3M in the presence of acetohydroxamic acid (AHA) or oxalic acid (OA) to mitigate Pu extraction, and the separation of U from Np was successful at nitric acid concentrations of less than 1M in the presence of AHA, OA, or sodium nitrite to mitigate Np extraction. Americium was not well extracted under any condition studied. Copyright © 2014 Elsevier B.V. All rights reserved.

Insight into mechanical properties and thermoelectric efficiency of Zr2CoZ (Z  =  Si, Ge) Heusler alloys

NASA Astrophysics Data System (ADS)

Yousuf, Saleem; Gupta, Dinesh C.

2017-11-01

We investigated the electronic, mechanical and thermoelectric properties of Zr2CoZ (Z  =  Si, Ge) Heusler alloys using the first-principles calculation. From the analysis of various elastic constants, the shear and Young’s moduli, Poisson’s ratio, the ductile nature of the alloys is predicted. Thermoelectric coefficients viz., Seebeck, electrical conductivity and figure of merit show Zr2CoZ alloys as n-type thermoelectric materials showing linearly increasing Seebeck coefficient with temperature. The value of total absolute Seebeck coefficients at 1200 K of Zr2CoSi and Zr2CoGe are 60 µV K-1 and 40 µV K-1 respectively mainly because of the existence of almost flat conduction bands along L to Г directions of high symmetry Brillouin zone. Further, the chemical potential variation of power factor confirms the n-type doping fruitful to increase their TE performance. The figure of merit achieves an upper-limit of 0.95 at 850 K and can favour their use for waste heat recovery at higher temperatures and thermoelectric spin generators.

Microstructure and mechanical properties of rapidly solidified B2-type Zr–Co alloys containing a second phase of Zr2Co

NASA Astrophysics Data System (ADS)

Li, Peiyou

2018-04-01

Microstructure and mechanical properties of B2-type Zr–Co alloys containing a second phase (Zr2Co) were investigated. Results show that the as-cast Zr52Co48, Zr54Co46, and Zr56Co44 alloys are composed of a eutectic structure of B2 and Zr2Co phases. Relative amounts of Zr2Co phases increase with an increase in Zr content. Zr54Co46 exhibits high yield strength, high Vickers hardness, good ductility, and high toughness values, and thus, Zr54Co46 can be considered to be a novel engineering material. The increase in strength and decrease in plastic strain of the alloys are mainly attributed to the increase in high strength of the brittle Zr2Co phase and to grain refining of the B2 matrix phase.

Distribution trends and influence of 4d transition metal elements (Ru, Rh and Pd) doping on mechanical properties and martensitic transformation temperature of B2-ZrCu phase

NASA Astrophysics Data System (ADS)

Guo, Fuda; Zhan, Yongzhong

2017-12-01

The prediction for distribution trends and effect of three 4d transition metal elements (Ru, Rh and Pd) on mechanical properties and martensitic transformation temperature of B2-ZrCu phase were investigated by first-principles calculations. The convex surface of formation energy suggests that the alloying elements prefer to occupy the Cu sites in B2-ZrCu phase and the dopants studied in present are able to strengthen the phase stability. The calculated results of substitutional formation energy suggest that the distribution trend of dopants in B2-ZrCu phase is Ru > Rh > Pd below the dopant concentration 9 at. %, and the distribution trend is Rh > Pd > Ru from 9 at. % to 12.5 at. %. The elastic constants and mechanical properties including bulk modulus and shear modulus were calculated and discussed. The brittleness/ductility characteristic was investigated using the B/G ratio, Poisson's ratio v and Cauchy pressure Cp. The martensitic transformation temperature (Ms) and melting point (Tm) were predicted by using two cubic elastic moduli (C‧ and C44). The prediction results suggest that only the Ms of Zr8Cu7Pd is higher than the parent. The martensitic transformation temperatures of other compounds decrease with the addition of 4d transition metal dopants. Finally, the electronic structures and electron density different were discussed to reveal the bonding characteristics.

Crystallographic and Mössbauer investigations on Np1- xPuxB2

NASA Astrophysics Data System (ADS)

Chipaux, R.; Bonnisseau, D.; Bogé, M.; Larroque, J.

1988-08-01

The diborides of neptunium and plutonium and their solid solutions Np 1- xPu xB 2 have been synthesized by direct reaction with a good purity. The lattice parameters follow Vegard's law. The magnetic properties of the samples containing neptunium have been investigated by Mössbauer spectrometry. The isomer shift is almost constant in all compounds (-14.5 (0.2) mm/s resp. to NpAl 2), suggesting tetravalent Np ions. At high temperatures, a large quadrupolar interaction, clearly connected to the crystal structure, is observed in all compounds, decreasing slowly with the neptunium concentration. At low temperature, magnetic patterns appear for x ⩽ 0.5. The magnetic moments are ordered perpendicular to the c-axis and equal to 0.57μ B for x = 0. In Np 0.5Pu 0.5B 2 and, in less degree in Np 0.7Pu 0.3B 2 and Np 0.33Pu 0.67B 2, magnetic fluctuations are detec ted.

Depth profile of 236U/238U in soil samples in La Palma, Canary Islands

PubMed Central

Srncik, M.; Steier, P.; Wallner, G.

2011-01-01

The vertical distribution of the 236U/238U isotopic ratio was investigated in soil samples from three different locations on La Palma (one of the seven Canary Islands, Spain). Additionally the 240Pu/239Pu atomic ratio, as it is a well establish tool for the source identification, was determined. The radiochemical procedure consisted of a U separation step by extraction chromatography using UTEVA® Resin (Eichrom Technologies, Inc.). Afterwards Pu was separated from Th and Np by anion exchange using Dowex 1x2 (Dow Chemical Co.). Furthermore a new chemical procedure with tandem columns to separate Pu and U from the matrix was tested. For the determination of the uranium and plutonium isotopes by alpha spectrometry thin sources were prepared by microprecipitation techniques. Additionally these fractions separated from the soil samples were measured by Accelerator Mass Spectrometry (AMS) to get information on the isotopic ratios 236U/238U, 240Pu/239Pu and 236U/239Pu, respectively. The 236U concentrations [atoms/g] in each surface layer (∼2 cm) were surprisingly high compared to deeper layers where values around two orders of magnitude smaller were found. Since the isotopic ratio 240Pu/239Pu indicated a global fallout signature we assume the same origin as the probable source for 236U. Our measured 236U/239Pu value of around 0.2 is within the expected range for this contamination source. PMID:21481502

Recovery of UO[sub 2]/PuO[sub 2] in IFR electrorefining process

DOEpatents

Tomczuk, Z.; Miller, W.E.

1994-10-18

A process is described for converting PuO[sub 2] and UO[sub 2] present in an electrorefiner to the chlorides, by contacting the PuO[sub 2] and UO[sub 2] with Li metal in the presence of an alkali metal chloride salt substantially free of rare earth and actinide chlorides for a time and at a temperature sufficient to convert the UO[sub 2] and PuO[sub 2] to metals while converting Li metal to Li[sub 2]O. Li[sub 2]O is removed either by reducing with rare earth metals or by providing an oxygen electrode for transporting O[sub 2] out of the electrorefiner and a cathode, and thereafter applying an emf to the electrorefiner electrodes sufficient to cause the Li[sub 2]O to disassociate to O[sub 2] and Li metal but insufficient to decompose the alkali metal chloride salt. The U and Pu and excess lithium are then converted to chlorides by reaction with CdCl[sub 2].

Recovery of UO.sub.2 /Pu O.sub.2 in IFR electrorefining process

DOEpatents

Tomczuk, Zygmunt; Miller, William E.

1994-01-01

A process for converting PuO.sub.2 and UO.sub.2 present in an electrorefiner to the chlorides, by contacting the PuO.sub.2 and UO.sub.2 with Li metal in the presence of an alkali metal chloride salt substantially free of rare earth and actinide chlorides for a time and at a temperature sufficient to convert the UO.sub.2 and PuO.sub.2 to metals while converting Li metal to Li.sub.2 O. Li.sub.2 O is removed either by reducing with rare earth metals or by providing an oxygen electrode for transporting O.sub.2 out of the electrorefiner and a cathode, and thereafter applying an emf to the electrorefiner electrodes sufficient to cause the Li.sub.2 O to disassociate to O.sub.2 and Li metal but insufficient to decompose the alkali metal chloride salt. The U and Pu and excess lithium are then converted to chlorides by reaction with CdCl.sub.2.

Surface Characterization of ZrO2/Zr Coating on Ti6Al4V and IN VITRO Evaluation of Corrosion Behavior and Biocompatibility

NASA Astrophysics Data System (ADS)

Wang, Ruoyun; Sun, Yonghua; He, Xiaojing; Gao, Yuee; Yao, Xiaohong

Biocompatibility is crucial for implants. In recent years, numerous researches were conducted aiming to modify titanium alloys, which are the most extensively used materials in orthopedic fields. The application of zirconia in the biomedical field has recently been explored. In this study, the biological ZrO2 coating was synthesized on titaniumalloy (Ti6Al4V) substrates by a duplex-treatment technique combining magnetron sputtering with micro-arc oxidation (MAO) in order to further improve the corrosion resistance and biocompatibility of Ti6Al4V alloys. The microstructures and phase constituents of the coatings were characterized by scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), the surface wettability was evaluated by contact angle measurements. The results show that ZrO2 coatings are porous with pore sizes less than 2μm and consist predominantly of the tetragonal ZrO2 (t-ZrO2) and cubic ZrO2(c-ZrO2) phase. Electrochemical tests indicate that the corrosion rate of Ti6Al4V substrates is appreciably reduced after surface treatment in the phosphate buffer saline (PBS). In addition, significantly improved cell adhesion and growth were observed from the ZrO2/Zr surface. Therefore, the hybrid approach of magnetron sputtering and MAO provides a surface modification for Ti6Al4V to achieve acceptable corrosion resistance and biocompatibility.

Nitrogen-containing superlow-carbon austenitic steel 02Kh25N22AM2

NASA Astrophysics Data System (ADS)

Fe'ldgandler, É. G.; Svistunova, T. V.; Savkina, L. Ya.; Lapshina, O. B.

1996-02-01

At present the equipment for manufacturing carbamide mineral fertilizers is produced from domestic steel 03Kh17N14M3 having "carbamide quality." Imported equipment also used in the industry is produced from steel of the 25-22-2 (Cr -Ni-Mo) type shipped by various firms, namely, 2RE69 (Sandvik, Sweden), 254SFER (Avesta, Sweden), 2522LCN (VDM, Germany), DM 1.4466 (Germany), and X2CrNiMo 25-22-2 (Dalmine, Italy). The imported steels are used because in some units steel 03Khl7Nl4M3 does not provide the requisite corrosion resistance in an intensified process of carbamide manufacturing. We currently possess domestic high-alloyed steel for producing new and repairing imported equipment operating under the severe conditions of carbamide synthesis. The present paper concerns the structure, mechanical properties, and corrosion resistance of industrially produced steel 02Kh25N22AM2 (ChS-108) and the recommended range of its application.

Examination of Multiphase (Zr,Ti)(V,Cr,Mn,Ni)2 Ni-MH Electrode Alloys: Part I. Dendritic Solidification Structure

NASA Astrophysics Data System (ADS)

Boettinger, W. J.; Newbury, D. E.; Wang, K.; Bendersky, L. A.; Chiu, C.; Kattner, U. R.; Young, K.; Chao, B.

2010-08-01

The solidification microstructures of three nine-element Zr-Ni-based AB2 type C14/C15 Laves hydrogen storage alloys are determined. The selected compositions represent a class of alloys being examined for usage as an MH electrode in nickel metal-hydride batteries that often have their best properties in the cast state. Solidification is accomplished by dendritic growth of hexagonal C14 Laves phase, peritectic solidification of cubic C15 Laves phase, and formation of cubic B2 phase in the interdendritic regions. The B2 phase decomposes in the solid state into a complex multivariate platelike structure containing Zr-Ni-rich intermetallics. The observed sequence C14/C15 upon solidification agrees with predictions using effective compositions and thermodynamic assessments of the ternary systems, Ni-Cr-Zr and Cr-Ti-Zr. Experimentally, the closeness of the compositions of the C14 and C15 phases required the use of compositional mapping with an energy dispersive detector capable of processing a very high X-ray flux to locate regions in the microstructure for quantitative composition measurement and transmission electron microscope examination.

Nanocrystallization of Zr-Cu-Ni-Al-Au glassy alloys during severe plastic deformation

NASA Astrophysics Data System (ADS)

Yamada, Masahiro; Kamisato, Ryo; Yamasaki, Tohru; Adachi, Hiroki; Tsuchiya, Koichi; Yokoyama, Yoshihiko

2014-08-01

A study has been carried out into the formation of nanocrystalline grains during high-pressure torsion (HPT) deformation of Zr65Cu17Ni5Al10Au3 bulk alloys prepared using tilt casting. As a preliminary to this, X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses were carried out on as-cast Zr65+xCu17-xNi5Al10Au3 (x=0~5 at.%) and Zr65Cu20Ni5Al10Au3 alloys, in order to determine the effect on the microstructure of the excess Zr content x and the presence of Au. From the XRD patterns, it was determined that all of the alloys had a metallic glassy nature. For Zr65Cu17Ni5Al10Au3, the DSC results indicated the presence of a wide supercooled liquid region between the glass transition temperature (Tg) of 644 K and the crystallization temperature of 763 K, where the stable body-centered tetragonal Zr2Cu phase was formed. In contrast, for the Zr65+xCu17-xNi5Al10Au3 alloys, precipitation of an icosahedral quasicrystalline phase (I-phase) was observed in the supercooled liquid region at about 715 K. HPT deformation of the Zr65Cu17Ni5Al10Au3 alloys was carried out under a high pressure of 5 GPa. Both as-cast specimens and those annealed at Tg-50 K for 90 min were used. Following a single HPT rotation (N=1), transmission electron microscopy identified the presence of face- centered cubic Zr2Ni precipitates in the as-cast alloy, with a size of about 50 nm. For the annealed alloy, a high density of I-phase precipitates with sizes of less than 10 nm was observed following HPT with N=10, indicating that the combination of severe plastic deformation and annealing is effective at producing extremely small grains.

Electronic structure and glass forming ability in early and late transition metal alloys

NASA Astrophysics Data System (ADS)

Babić, E.; Ristić, R.; Figueroa, I. A.; Pajić, D.; Skoko, Ž.; Zadro, K.

2018-03-01

A correlation between the change in magnetic susceptibility (Δχexp) upon crystallisation of Cu-Zr and Hf metallic glasses (MG) with their glass forming ability (GFA) observed recently, is found to apply to Cu-Ti and Zr-Ni alloys, too. In particular, small Δχexp, which reflects similar electronic structures, ES, of glassy and corresponding crystalline alloys, corresponds to high GFA. Here, we studied Δχexp for five Cu-Ti and four Cu-Zr and Ni-Zr MGs. The fully crystalline final state of all alloys was verified from X-ray diffraction patterns. The variation of GFA with composition in Cu-Ti, Cu-Zr and Cu-Hf MGs was established from the variation of the corresponding critical casting thickness, dc. Due to the absence of data for dc in Ni-Zr MGs their GFA was described using empirical criteria, such as the reduced glass transition temperature. A very good correlation between Δχexp and dc (and/or other criteria for GFA) was observed for all alloys studied. The correlation between the ES and GFA showed up best for Cu-Zr and NiZr2 alloys where direct data for the change in ES (ΔES) upon crystallisation are available. The applicability of the Δχexp (ΔES) criterion for high GFA (which provides a simple way to select the compositions with high GFA) to other metal-metal MGs (including ternary and multicomponent bulk MGs) is briefly discussed.

Pressure-induced superconductivity in H2-containing hydride PbH4(H2)2

PubMed Central

Cheng, Ya; Zhang, Chao; Wang, Tingting; Zhong, Guohua; Yang, Chunlei; Chen, Xiao-Jia; Lin, Hai-Qing

2015-01-01

High pressure structure, stability, metallization, and superconductivity of PbH4(H2)2, a H2-containing compound combining one of the heaviest elements with the lightest element, are investigated by the first-principles calculations. The metallic character is found over the whole studied pressure range, although PbH4(H2)2 is metastable and easily decompose at low pressure. The decomposition pressure point of 133 GPa is predicted above which PbH4(H2)2 is stable both thermodynamically and dynamically with the C2/m symmetry. Interestedly, all hydrogen atoms pairwise couple into H2 quasi-molecules and remain this style up to 400 GPa in the C2/m structure. At high-pressure, PbH4(H2)2 tends to form the Pb-H2 alloy. The superconductivity of Tc firstly rising and then falling is observed in the C2/m PbH4(H2)2. The maximum of Tc is about 107 K at 230 GPa. The softening of intermediate-frequency phonon induced by more inserted H2 molecules is the main origin of the high Tc. The results obtained represent a significant step toward the understanding of the high pressure behavior of metallic hydrogen and hydrogen-rich materials, which is helpful for obtaining the higher Tc. PMID:26559369

Synthesis and characterisation of PuPO4 - a potential analytical standard for EPMA actinide quantification

NASA Astrophysics Data System (ADS)

Wright, K. E.; Popa, K.; Pöml, P.

2018-01-01

Transmutation nuclear fuels contain weight percentage quantities of actinide elements, including Pu, Am and Np. Because of the complex spectra presented by actinide elements using electron probe microanalysis (EPMA), it is necessary to have relatively pure actinide element standards to facilitate overlap correction and accurate quantitation. Synthesis of actinide oxide standards is complicated by their multiple oxidation states, which can result in inhomogeneous standards or standards that are not stable at atmospheric conditions. Synthesis of PuP4 results in a specimen that exhibits stable oxidation-reduction chemistry and is sufficiently homogenous to serve as an EPMA standard. This approach shows promise as a method for producing viable actinide standards for microanalysis.

Electrical resistivity in Zr48Nb8Cu12Fe8Be24 glassy and crystallized alloys

NASA Astrophysics Data System (ADS)

Bai, H. Y.; Tong, C. Z.; Zheng, P.

2004-02-01

The electrical resistivity of Zr48Nb8Cu12Fe8Be24 bulk metallic glassy and crystallized alloys in the temperature range of 4.2-293 K is investigated. It is found that the resistivity in glassy and crystallized states shows opposite temperature coefficients. For the metallic glass, the resistivity shows a negative logarithmic dependence at temperatures below 16 K, whereas it has more normal behavior for the crystallized alloy. At higher temperatures, the resistivity in both glassy and crystallized alloys shows dependence upon both T and T2, but the signs of the T and T2 terms are opposite. The results are interpreted in terms of scattering from two-level tunneling states in glasses and the generalized Ziman diffraction model.

Modelling the thermal conductivity of (U xTh 1-x)O 2 and (U xPu 1-x)O 2

DOE PAGES

Cooper, M. W. D.; Middleburgh, S. C.; Grimes, R. W.

2015-07-15

The degradation of thermal conductivity due to the non-uniform cation lattice of (U xTh 1-x)O 2 and (U xPu 1-x)O 2 solid solutions has been investigated by molecular dynamics, using the non-equilibrium method, from 300 to 2000 K. Degradation of thermal conductivity is predicted in (U xTh 1-x)O 2 and (U xPu 1-x)O 2 as compositions deviate from the pure end members: UO 2, PuO 2 and ThO 2. The reduction in thermal conductivity is most apparent at low temperatures where phonon-defect scattering dominates over phonon-phonon interactions. The effect is greater for (U xTh 1-x)O 2 than U xPu 1-x)Omore » 2 due to the greater mismatch in cation size. Parameters for an analytical expressions have been developed that describe the predicted thermal conductivities over the full temperature and compositional ranges. Finally, these expressions may be used in higher level fuel performance codes.« less

The interaction of molecular hydrogen with α-radiolytic oxidants on a (U,Pu)O2 surface

NASA Astrophysics Data System (ADS)

Bauhn, Lovisa; Hansson, Niklas; Ekberg, Christian; Fors, Patrik; Delville, Rémi; Spahiu, Kastriot

2018-07-01

In order to assess the impact of α-radiolysis of water on the oxidative dissolution of spent fuel, an un-irradiated, annealed MOX fuel pellet with high content of Pu (∼24 wt%), and a specific α-activity of 4.96 GBq/gMOX, was leached in carbonate-containing solutions of low ionic strength. The high Pu content in the pellet stabilizes the (U,Pu)O2(s) matrix towards oxidative dissolution, whereas the α-decays emitted from the surface are expected to produce ∼3.6 × 10-7 mol H2O2/day, contributing to the oxidative dissolution of the pellet. Two sets of leaching tests were conducted under different redox conditions: Ar gas atmosphere and deuterium gas atmosphere. A relatively slow increase of the U and Pu concentrations was observed in the Ar case, with U concentrations increasing from 1·10-6 M after 1 h to ∼7 × 10-5 M after 58 days. Leaching under an atmosphere starting at 1 MPa deuterium gas was undertaken in order to evaluate any effect of dissolved hydrogen on the radiolytic dissolution of the pellet, as well as to investigate any potential recombination of the α-radiolytic products with dissolved deuterium. For the latter purpose, isotopic analysis of the D/H content was carried out on solution samples taken during the leaching. Despite the continuous production of radiolytic oxidants, the concentrations of U and Pu remained quite constant at the level of ∼3 × 10-8 M during the first 30 days, i.e. as long as the deuterium pressure remained higher than 0.8 MPa. These data rule out any oxidative dissolution of the pellet during the first month. The un-irradiated MOX fuel does not contain metallic ε-particles, hence it is mainly the interaction of radiolytic oxidants and dissolved deuterium with the surface of the mixed actinide oxide that causes the neutralization of the oxidants. This conclusion is supported by the steadily increasing levels of HDO measured in the leachate samples.

Functional fatigue behavior of superelastic beta Ti-22Nb-6Zr(at%) alloy for load-bearing biomedical applications.

PubMed

Sheremetyev, V; Brailovski, V; Prokoshkin, S; Inaekyan, K; Dubinskiy, S

2016-01-01

Ti-22Nb-6Zr (at.%) alloy with different processing-induced microstructures (highly-dislocated partially recovered substructure, polygonized nanosubgrained (NSS) dislocation substructure, and recrystallized structure) was subjected to strain-controlled tension-tension fatigue testing in the 0.2...1.5% strain range (run-out at 10^6 cycles). The NSS alloy obtained after cold-rolling with 0.3 true strain and post-deformation annealing at 600 °C showed the lowest Young's modulus and globally superior fatigue performance due to the involvement of reversible stress-induced martensitic transformation in the deformation process. This NSS structure appears to be suitable for biomedical applications with an extended variation range of loading conditions (orthopedic implants). Copyright © 2015 Elsevier B.V. All rights reserved.

First principles calculations of interactions of ZrCl4 precursors with the bare and hydroxylated ZrO2 surfaces

NASA Astrophysics Data System (ADS)

Iskandarova, I. M.; Knizhnik, A. A.; Bagatur'yants, A. A.; Potapkin, B. V.; Korkin, A. A.

2004-05-01

First-principles calculations have been performed to determine the structures and relative energies of different zirconium chloride groups chemisorbed on the tetragonal ZrO2(001) surface and to study the effects of the surface coverage with metal chloride groups and the degree of hydroxylation on the adsorption energies of metal precursors. It is shown that the molecular and dissociative adsorption energies of the ZrCl4 precursor on the bare t-ZrO2(001) surface are too small to hold ZrCl4 molecules on the surface during an atomic layer deposition (ALD) cycle at temperatures higher than 300°C. On the contrary, it has been found that molecular adsorption on the fully hydroxylated zirconia surface leads to the formation of a stable adsorbed complex. This strong adsorption of ZrCl4 molecules can lead to a decrease in the film growth rate of the ALD process at lower temperatures (<200°C). The energies of interaction between adsorbed ZrCl4 groups at a 50% surface coverage has been found to be relatively small, which explains the maximum film growth rate observed in the ZrCl4:H2O ALD process. Moreover, we found that the adsorbed ZrCl4 precursors after hydrolysis give rise to very stable hydroxyl groups, which can be responsible for film growth at high temperatures (up to 900°C).

Grain Refinement and Mechanical Properties of Cu–Cr–Zr Alloys with Different Nano-Sized TiCp Addition

PubMed Central

Zhang, Dongdong; Bai, Fang; Wang, Yong; Wang, Jinguo; Wang, Wenquan

2017-01-01

The TiCp/Cu master alloy was prepared via thermal explosion reaction. Afterwards, the nano-sized TiCp/Cu master alloy was dispersed by electromagnetic stirring casting into the melting Cu–Cr–Zr alloys to fabricate the nano-sized TiCp-reinforced Cu–Cr–Zr composites. Results show that nano-sized TiCp can effectively refine the grain size of Cu–Cr–Zr alloys. The morphologies of grain in Cu–Cr–Zr composites changed from dendritic grain to equiaxed crystal because of the addition and dispersion of nano-sized TiCp. The grain size decreased from 82 to 28 μm with the nano-sized TiCp content. Compared with Cu–Cr–Zr alloys, the ultimate compressive strength (σUCS) and yield strength (σ0.2) of 4 wt% TiCp-reinforced Cu–Cr–Zr composites increased by 6.7% and 9.4%, respectively. The wear resistance of the nano-sized TiCp-reinforced Cu–Cr–Zr composites increased with the increasing nano-sized TiCp content. The wear loss of the nano-sized TiCp-reinforced Cu–Cr–Zr composites decreased with the increasing TiCp content under abrasive particles. The eletrical conductivity of Cu–Cr–Zr alloys, 2% and 4% nano-sized TiCp-reinforced Cu–Cr–Zr composites are 64.71% IACS, 56.77% IACS and 52.93% IACS, respectively. PMID:28786937

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.

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.

Development of Ti-Nb-Zr alloys with high elastic admissible strain for temporary orthopedic devices.

PubMed

Ozan, Sertan; Lin, Jixing; Li, Yuncang; Ipek, Rasim; Wen, Cuie

2015-07-01

A new series of beta Ti-Nb-Zr (TNZ) alloys with considerable plastic deformation ability during compression test, high elastic admissible strain, and excellent cytocompatibility have been developed for removable bone tissue implant applications. TNZ alloys with nominal compositions of Ti-34Nb-25Zr, Ti-30Nb-32Zr, Ti-28Nb-35.4Zr and Ti-24.8Nb-40.7Zr (wt.% hereafter) were fabricated using the cold-crucible levitation technique, and the effects of alloying element content on their microstructures, mechanical properties (tensile strength, yield strength, compressive yield strength, Young's modulus, elastic energy, toughness, and micro-hardness), and cytocompatibilities were investigated and compared. Microstructural examinations revealed that the TNZ alloys consisted of β phase. The alloy samples displayed excellent ductility with no cracking, or fracturing during compression tests. Their tensile strength, Young's modulus, elongation at rupture, and elastic admissible strain were measured in the ranges of 704-839 MPa, 62-65 GPa, 9.9-14.8% and 1.08-1.31%, respectively. The tensile strength, Young's modulus and elongation at rupture of the Ti-34Nb-25Zr alloy were measured as 839 ± 31.8 MPa, 62 ± 3.6 GPa, and 14.8 ± 1.6%, respectively; this alloy exhibited the elastic admissible strain of approximately 1.31%. Cytocompatibility tests indicated that the cell viability ratios (CVR) of the alloys are greater than those of the control group; thus the TNZ alloys possess excellent cytocompatibility. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Sintering of compacts of UN, (U,Pu)N, and PuN

DOEpatents

Tennery, V.J.; Godfrey, T.G.; Bomar, E.S.

1973-10-16

>A method is provided for preparing a densified compact of a metal nitride selected from the group consisting of UN, (U,Pu)N, and PuN which comprises heating a green compact of at least one selected nitride in the mononitride single-phase region, as displayed by a phase diagram of the mononitride of said compact, in a nitrogen atmosphere at a pressure of nitrogen less than 760 torr. At a given temperature, this process produces a singlephase structure and a maximal sintered density as measured by mercury displacement. (Official Gazette)

Color tone and interfacial microstructure of white oxide layer on commercially pure Ti and Ti-Nb-Ta-Zr alloys

NASA Astrophysics Data System (ADS)

Miura-Fujiwara, Eri; Mizushima, Keisuke; Watanabe, Yoshimi; Kasuga, Toshihiro; Niinomi, Mitsuo

2014-11-01

In this study, the relationships among oxidation condition, color tone, and the cross-sectional microstructure of the oxide layer on commercially pure (CP) Ti and Ti-36Nb-2Ta-3Zr-0.3O were investigated. “White metals” are ideal metallic materials having a white color with sufficient strength and ductility like a metal. Such materials have long been sought for in dentistry. We have found that the specific biomedical Ti alloys, such as CP Ti, Ti-36Nb-2Ta-3Zr-0.3O, and Ti-29Nb-13Ta-4.6Zr, form a bright yellowish-white oxide layer after a particular oxidation heat treatment. The brightness L* and yellowness +b* of the oxide layer on CP Ti and Ti-36Nb-2Ta-3Zr-0.3O increased with heating time and temperature. Microstructural observations indicated that the oxide layer on Ti-29Nb-13Ta-4.6Zr and Ti-36Nb-2Ta-3Zr-0.3O was dense and firm, whereas a piecrust-like layer was formed on CP Ti. The results obtained in this study suggest that oxide layer coating on Ti-36Nb-2Ta-3Zr-0.3O is an excellent technique for dental applications.

Ternary ceramic alloys of Zr-Ce-Hf oxides

DOEpatents

Becher, P.F.; Funkenbusch, E.F.

1990-11-20

A ternary ceramic alloy is described which produces toughening of zirconia and zirconia composites through the stress transformation from tetragonal phase to monoclinic phase. This alloy, having the general formula Ce[sub x]Hf[sub y]Zr[sub 1[minus]x[minus]y]O[sub 2], is produced through the addition of appropriate amounts of ceria and hafnia to the zirconia. Typically, improved toughness is achieved with about 5 to about 15 mol % ceria and up to about 40 mol % hafnia. The preparation of alloys of these compositions are given together with data as to the densities, tetragonal phase content, hardness and fracture toughness. The alloys are useful in preparing zirconia bodies as well as reinforcing ceramic composites. 1 fig.

The Soft Magnetic Properties, and Temperature Stability, of Co-Fe-Zr-B Metallic Glasses

NASA Astrophysics Data System (ADS)

Bednarčík, J.; Kováč, J.; Roth, S.; Fűzer, J.; Kollár, P.; Varga, L.; Franz, H.

2008-01-01

In the present work multicomponent Co-based alloys with nominal composition Co72-x FexZr8B20 (x=10, 15, and 20 at. %) were synthesized by single-roller melt-spinning. The measurement of coercivity, Hc, reveals the soft magnetic behavior of investigated alloys. The value of Hc increases from 23 A/m for alloy with x=10 at. % up to 32 A/m for alloy with x=20 at. %. Further it was found that crystallization temperature of as-quenched alloys slightly varies with iron content and lays between 605 and 625°C. From the temperature dependence of magnetization it follows that partial substitution of cobalt by iron has positive influence on the Curie temperature of amorphous phase, Tam c, which increases from 300°C up to 462°C for alloy with x=10 at. % and x=2 0 at. %, respectively.

Grain Refinement and Mechanical Properties of Cu-Cr-Zr Alloys with Different Nano-Sized TiCp Addition.

PubMed

Zhang, Dongdong; Bai, Fang; Wang, Yong; Wang, Jinguo; Wang, Wenquan

2017-08-08

The TiC p /Cu master alloy was prepared via thermal explosion reaction. Afterwards, the nano-sized TiC p /Cu master alloy was dispersed by electromagnetic stirring casting into the melting Cu-Cr-Zr alloys to fabricate the nano-sized TiC p -reinforced Cu-Cr-Zr composites. Results show that nano-sized TiC p can effectively refine the grain size of Cu-Cr-Zr alloys. The morphologies of grain in Cu-Cr-Zr composites changed from dendritic grain to equiaxed crystal because of the addition and dispersion of nano-sized TiC p . The grain size decreased from 82 to 28 μm with the nano-sized TiC p content. Compared with Cu-Cr-Zr alloys, the ultimate compressive strength (σ UCS ) and yield strength (σ 0.2 ) of 4 wt% TiC p -reinforced Cu-Cr-Zr composites increased by 6.7% and 9.4%, respectively. The wear resistance of the nano-sized TiCp-reinforced Cu-Cr-Zr composites increased with the increasing nano-sized TiCp content. The wear loss of the nano-sized TiC p -reinforced Cu-Cr-Zr composites decreased with the increasing TiC p content under abrasive particles. The eletrical conductivity of Cu-Cr-Zr alloys, 2% and 4% nano-sized TiCp-reinforced Cu-Cr-Zr composites are 64.71% IACS, 56.77% IACS and 52.93% IACS, respectively.

Nanostructured Ti-Zr-Pd-Si-(Nb) bulk metallic composites: Novel biocompatible materials with superior mechanical strength and elastic recovery.

PubMed

Hynowska, A; Blanquer, A; Pellicer, E; Fornell, J; Suriñach, S; Baró, M D; Gebert, A; Calin, M; Eckert, J; Nogués, C; Ibáñez, E; Barrios, L; Sort, J

2015-11-01

The microstructure, mechanical behaviour, and biocompatibility (cell culture, morphology, and cell adhesion) of nanostructured Ti45 Zr15 Pd35- x Si5 Nbx with x = 0, 5 (at. %) alloys, synthesized by arc melting and subsequent Cu mould suction casting, in the form of rods with 3 mm in diameter, are investigated. Both Ti-Zr-Pd-Si-(Nb) materials show a multi-phase (composite-like) microstructure. The main phase is cubic β-Ti phase (Im3m) but hexagonal α-Ti (P63/mmc), cubic TiPd (Pm3m), cubic PdZr (Fm3m), and hexagonal (Ti, Zr)5 Si3 (P63/mmc) phases are also present. Nanoindentation experiments show that the Ti45 Zr15 Pd30 Si5 Nb5 sample exhibits lower Young's modulus than Ti45 Zr15 Pd35 Si5 . Conversely, Ti45 Zr15 Pd35 Si5 is mechanically harder. Actually, both alloys exhibit larger values of hardness when compared with commercial Ti-40Nb, (HTi-Zr-Pd-Si ≈ 14 GPa, HTi-Zr-Pd-Si-Nb ≈ 10 GPa and HTi-40Nb ≈ 2.7 GPa). Concerning the biological behaviour, preliminary results of cell viability performed on several Ti-Zr-Pd-Si-(Nb) discs indicate that the number of live cells is superior to 94% in both cases. The studied Ti-Zr-Pd-Si-(Nb) bulk metallic system is thus interesting for biomedical applications because of the outstanding mechanical properties (relatively low Young's modulus combined with large hardness), together with the excellent biocompatibility. © 2014 Wiley Periodicals, Inc.

Improving High-Temperature Tensile and Low-Cycle Fatigue Behavior of Al-Si-Cu-Mg Alloys Through Micro-additions of Ti, V, and Zr

NASA Astrophysics Data System (ADS)

Shaha, S. K.; Czerwinski, F.; Kasprzak, W.; Friedman, J.; Chen, D. L.

2015-07-01

High-temperature tensile and low-cycle fatigue tests were performed to assess the influence of micro-additions of Ti, V, and Zr on the improvement of the Al-7Si-1Cu-0.5Mg (wt pct) alloy in the as-cast condition. Addition of transition metals led to modification of microstructure where in addition to conventional phases present in the Al-7Si-1Cu-0.5Mg base, new thermally stable micro-sized Zr-Ti-V-rich phases Al21.4Si4.1Ti3.5VZr3.9, Al6.7Si1.2TiZr1.8, Al2.8Si3.8V1.6Zr, and Al5.1Si35.4Ti1.6Zr5.7Fe were formed. The tensile tests showed that with increasing test temperature from 298 K to 673 K (25 °C to 400 °C), the yield stress and tensile strength of the present studied alloy decreased from 161 to 84 MPa and from 261 to 102 MPa, respectively. Also, the studied alloy exhibited 18, 12, and 5 pct higher tensile strength than the alloy A356, 354 and existing Al-Si-Cu-Mg alloy modified with additions of Zr, Ti, and Ni, respectively. The fatigue life of the studied alloy was substantially longer than those of the reference alloys A356 and the same Al-7Si-1Cu-0.5Mg base with minor additions of V, Zr, and Ti in the T6 condition. Fractographic analysis after tensile tests revealed that at the lower temperature up to 473 K (200 °C), the cleavage-type brittle fracture for the precipitates and ductile fracture for the matrix were dominant while at higher temperature fully ductile-type fracture with debonding and pull-out of cracked particles was identified. It is believed that the intermetallic precipitates containing Zr, Ti, and V improve the alloy performance at increased temperatures.

Microstructure and Elevated Temperature Properties of a Refractory TaNbHfZrTi Alloy

DTIC Science & Technology

2012-01-24

composition of the TaNbHfZrTi alloy produced by vacuum arc melting Composition Ta Nb Hf Zr Ti at.% 19.68 18.93 20.46 21.23 19.7 wt. % 30.04 14.84 30.82 16.34...metallic materials with higher melting points, such as refractory molybdenum (Mo) and niobium ( Nb ) alloys, are examined as alternatives by academic and...creep resistance are the key properties of these alloys, since considerable alloy softening generally occurs at tempera- tures above *0.5 0.6 Tm

High temperature heat capacity of (U, Am)O2±x

NASA Astrophysics Data System (ADS)

Epifano, E.; Beneš, O.; Vălu, O. S.; Zappey, J.; Lebreton, F.; Martin, P. M.; Guéneau, C.; Konings, R. J. M.

2017-10-01

Mixed uranium and americium dioxides (U, Am)O2±x are candidates as possible transmutation targets for generation IV reactors. In this work, the enthalpy increments of this solid solution were measured in the 470-1750 K temperature range by drop calorimetry for Am/(Am + U) ratios equal to 0.32, 0.39, 0.49, 0.58 and 0.68. Then, the heat capacity functions were obtained by derivation of the enthalpy data. The results of this work were compared to the heat capacity and enthalpy functions reported in the literature for the UO2 [1] and AmO2 [2] binary oxides and for the U0.9Am0.1O2±x, U0.8Am0.2O2±x mixed oxides [3]. From the obtained trend, it was found out that an excess contribution to the enthalpy increment appears for T > 1100 K in the compositions with Am/(Am + U)≥0.4 and a possible explanation attributing this effect to oxygen hypostoichiometry is provided. Finally, to verify the hypothesis, thermodynamic computations based on the CALPHAD method were performed for AmO2-x under air and the results confirmed that the source of the excess contribution is the formation of oxygen vacancies.

METHOD OF SUPPRESSING UAl$sub 4$ FORMATION IN U-Al ALLOYS

DOEpatents

Picklesimer, M.L.; Thurber, W.C.

1960-08-23

A method is given for suppressing the formation of UAl/sub 4/ in uranium- - aluminum alloys, thereby rendering these alloys more easily workable. The method comprises incorporating in the base alloy a Group Four element selected from the group consisting of Si, Ti, Ge, Zr, and Sn, the addition preferably being within the range of 0.5to20at.%.

On the Potential of Bulk Metallic Glasses for Dental Implantology: Case Study on Ti40Zr10Cu36Pd14

PubMed Central

Liens, Alethea; Etiemble, Aurélien; Rivory, Pascaline; Balvay, Sandra; Pelletier, Jean-Marc; Cardinal, Sandrine; Fabrègue, Damien; Kato, Hidemi; Munhoz, Tais; Adrien, Jerome; Courtois, Nicolas; Hartmann, Daniel J.; Chevalier, Jérôme

2018-01-01

Ti40Zr10Cu36Pd14 Bulk Metallic Glass (BMG) appears very attractive for future biomedical applications thanks to its high glass forming ability, the absence of toxic elements such as Ni, Al or Be and its good mechanical properties. For the first time, a complete and exhaustive characterization of a unique batch of this glassy alloy was performed, together with ISO standard mechanical tests on machined implant-abutment assemblies. The results were compared to the benchmark Ti-6Al-4V ELI (Extra-Low-Interstitial) to assess its potential in dental implantology. The thermal stability, corrosion and sterilization resistance, cytocompatibility and mechanical properties were measured on samples with a simple geometry, but also on implant-abutment assemblies’ prototypes. Results show that the glassy alloy exhibits a quite high thermal stability, with a temperature range of 38 °C between the glass transition and crystallization, a compressive strength of 2 GPa, a certain plastic deformation (0.7%), a hardness of 5.5 GPa and a toughness of 56 MPa.√m. Moreover, the alloy shows a relatively lower Young’s modulus (96 GPa) than the Ti-6Al-4V alloy (110–115 GPa), which is beneficial to limit bone stress shielding. The BMG shows a satisfactory cytocompatibility, a high resistance to sterilization and a good corrosion resistance (corrosion potential of −0.07 V/SCE and corrosion current density of 6.0 nA/cm2), which may ensure its use as a biomaterial. Tests on dental implants reveal a load to failure 1.5-times higher than that of Ti-6Al-4V and a comparable fatigue limit. Moreover, implants could be machined and sandblasted by methods usually conducted for titanium implants, without significant degradation of their amorphous nature. All these properties place this metallic glass among a promising class of materials for mechanically-challenging applications such as dental implants. PMID:29415490

Study of a ;hot; particle with a matrix of U-bearing metallic Zr: Clue to supercriticality during the Chernobyl nuclear accident

NASA Astrophysics Data System (ADS)

Pöml, P.; Burakov, B.

2017-05-01

This paper is dedicated to the 30th anniversary of the severe nuclear accident that occurred at the Chernobyl NPP on 26 April 1986. A detailed study on a Chernobyl "hot" particle collected from contaminated soil was performed. Optical and electron microscopy, as well as quantitative x-ray microbeam analysis methods were used to determine the properties of the sample. The results show that the particle (≈ 240 x 165 μm) consists of a metallic Zr matrix containing 2-3 wt. % U and bearing veins of an U,Nb admixture. The metallic Zr matrix contains two phases with different amounts of O with the atomic proportions (U,Zr,Nb)0.73O0.27 and (U,Zr,Nb)0.61O0.39. The results confirm the interaction between UO2 fuel and zircaloy cladding in the reactor core. To explain the process of formation of the particle, its properties are compared to laboratory experiments. Because of the metallic nature of the particle it is concluded that it must have formed during a very high temperature (> 2400∘C) process that lasted for only a very short time (few microseconds or less); otherwise the particle should have been oxidised. Such a rapid very high temperature process indicates that at least part of the reactor core could have been supercritical prior to an explosion as it was previously suggested in the literature.

Low-pressure oxidation of Cb-1Zr alloy.

NASA Technical Reports Server (NTRS)

Lyon, T. F.

1971-01-01

Resistively heated strip specimens of Cb-1Zr alloy were exposed at 927 C in a vacuum chamber at various levels of total pressure in the 1-microtorr range and at various oxygen partial pressures in the .1-microtorr range. Oxygen reaction rates (sticking probabilities) were found to depend on whether or not the specimens were annealed immediately before the test exposure. It is shown that a normally undetectable oxide film exists on the Cb-1Zr surface as a result of oxidation by ambient air, and this film reduces the sticking probability as compared with a clean metal surface. The alloy is considerably strengthened by addition of oxygen to a level of about 6000 ppm, while still maintaining reasonably good room temperature ductility.

Improvement of bio-corrosion resistance for Ti42Zr40Si15Ta3 metallic glasses in simulated body fluid by annealing within supercooled liquid region.

PubMed

Huang, C H; Lai, J J; Wei, T Y; Chen, Y H; Wang, X; Kuan, S Y; Huang, J C

2015-01-01

The effects of the nanocrystalline phases on the bio-corrosion behavior of highly bio-friendly Ti42Zr40Si15Ta3 metallic glasses in simulated body fluid were investigated, and the findings are compared with our previous observations from the Zr53Cu30Ni9Al8 metallic glasses. The Ti42Zr40Si15Ta3 metallic glasses were annealed at temperatures above the glass transition temperature, Tg, with different time periods to result in different degrees of α-Ti nano-phases in the amorphous matrix. The nanocrystallized Ti42Zr40Si15Ta3 metallic glasses containing corrosion resistant α-Ti phases exhibited more promising bio-corrosion resistance, due to the superior pitting resistance. This is distinctly different from the previous case of the Zr53Cu30Ni9Al8 metallic glasses with the reactive Zr2Cu phases inducing serious galvanic corrosion and lower bio-corrosion resistance. Thus, whether the fully amorphous or partially crystallized metallic glass would exhibit better bio-corrosion resistance, the answer would depend on the crystallized phase nature. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of mechanical and transport properties of Zr2CoSi Heusler alloy

NASA Astrophysics Data System (ADS)

Yousuf, Saleem; Khandy, S. A.; Bhat, T. M.; Gupta, D. C.

2017-05-01

Systematic investigation of mechanical and transport properties of Zr2CoSi within the density functional theory have been analysed. From the elastic constants, the shear modulus, Young's modulus, Poisson's ratio, we conclude the ductile nature of alloy. Thermoelectric properties show that Zr2CoSi as an n-type thermoelectric material with a higher increase in Seebeck coefficient with temperature. Further the power factor analysis confirms the heavily doping of the alloy fruitful for increase in thermoelectric performance and its use for the future thermoelectric spin generators.

Pu-ZR Alloy high-temperature activation-measurement foil

DOEpatents

McCuaig, Franklin D.

1977-08-02

A nuclear reactor fuel alloy consists essentially of from slightly greater than 7 to about 4 w/o zirconium, balance plutonium, and is characterized in that the alloy is castable and is rollable to thin foils. A preferred embodiment of about 7 w/o zirconium, balance plutonium, has a melting point substantially above the melting point of plutonium, is rollable to foils as thin as 0.0005 inch thick, and is compatible with cladding material when repeatedly cycled to temperatures above 650.degree. C. Neutron flux densities across a reactor core can be determined with a high-temperature activation-measurement foil which consists of a fuel alloy foil core sandwiched and sealed between two cladding material jackets, the fuel alloy foil core being a 7 w/o zirconium, plutonium foil which is from 0.005 to 0.0005 inch thick.

On the crystallization kinetics of Zr-(Co,Ni)-Al bulk metallic glasses

NASA Astrophysics Data System (ADS)

Qin, X. M.; Zhang, Q. F.; Duan, X. Y.; Wang, X. C.; Jiang, Y. H.; Zhou, R.; Tan, J.

2017-07-01

Zr-based amorphous alloys are promising materials applied in engineering field, due to their strong glass-forming ability, outstanding mechanical properties and relatively low cost. In this work, the crystallization kinetics of Zr56Co18-xNixAl16 (x = 0, 2, 4 and 8; marked as Ni0, Ni2, Ni4 and Ni8, respectively) alloys are investigated in detail. The results show that, due to the addition of Ni, the glass transition of the alloys presents obvious dynamic characteristics, i.e., with the increasing heating rate, all characteristic temperatures are shifted to higher temperature. By fitting the Kissinger equation, the glass transition activation energy of Ni8 is the highest, indicating that Ni8 is much more difficult to crystallize. Therefore, the Ni8 alloy has the strongest anti-crystallization ability in the Zr56Co18-xNixAl16 alloys investigated.

Combinatorial development of antibacterial Zr-Cu-Al-Ag thin film metallic glasses.

PubMed

Liu, Yanhui; Padmanabhan, Jagannath; Cheung, Bettina; Liu, Jingbei; Chen, Zheng; Scanley, B Ellen; Wesolowski, Donna; Pressley, Mariyah; Broadbridge, Christine C; Altman, Sidney; Schwarz, Udo D; Kyriakides, Themis R; Schroers, Jan

2016-05-27

Metallic alloys are normally composed of multiple constituent elements in order to achieve integration of a plurality of properties required in technological applications. However, conventional alloy development paradigm, by sequential trial-and-error approach, requires completely unrelated strategies to optimize compositions out of a vast phase space, making alloy development time consuming and labor intensive. Here, we challenge the conventional paradigm by proposing a combinatorial strategy that enables parallel screening of a multitude of alloys. Utilizing a typical metallic glass forming alloy system Zr-Cu-Al-Ag as an example, we demonstrate how glass formation and antibacterial activity, two unrelated properties, can be simultaneously characterized and the optimal composition can be efficiently identified. We found that in the Zr-Cu-Al-Ag alloy system fully glassy phase can be obtained in a wide compositional range by co-sputtering, and antibacterial activity is strongly dependent on alloy compositions. Our results indicate that antibacterial activity is sensitive to Cu and Ag while essentially remains unchanged within a wide range of Zr and Al. The proposed strategy not only facilitates development of high-performing alloys, but also provides a tool to unveil the composition dependence of properties in a highly parallel fashion, which helps the development of new materials by design.

Combinatorial development of antibacterial Zr-Cu-Al-Ag thin film metallic glasses

NASA Astrophysics Data System (ADS)

Liu, Yanhui; Padmanabhan, Jagannath; Cheung, Bettina; Liu, Jingbei; Chen, Zheng; Scanley, B. Ellen; Wesolowski, Donna; Pressley, Mariyah; Broadbridge, Christine C.; Altman, Sidney; Schwarz, Udo D.; Kyriakides, Themis R.; Schroers, Jan

2016-05-01

Metallic alloys are normally composed of multiple constituent elements in order to achieve integration of a plurality of properties required in technological applications. However, conventional alloy development paradigm, by sequential trial-and-error approach, requires completely unrelated strategies to optimize compositions out of a vast phase space, making alloy development time consuming and labor intensive. Here, we challenge the conventional paradigm by proposing a combinatorial strategy that enables parallel screening of a multitude of alloys. Utilizing a typical metallic glass forming alloy system Zr-Cu-Al-Ag as an example, we demonstrate how glass formation and antibacterial activity, two unrelated properties, can be simultaneously characterized and the optimal composition can be efficiently identified. We found that in the Zr-Cu-Al-Ag alloy system fully glassy phase can be obtained in a wide compositional range by co-sputtering, and antibacterial activity is strongly dependent on alloy compositions. Our results indicate that antibacterial activity is sensitive to Cu and Ag while essentially remains unchanged within a wide range of Zr and Al. The proposed strategy not only facilitates development of high-performing alloys, but also provides a tool to unveil the composition dependence of properties in a highly parallel fashion, which helps the development of new materials by design.

Combinatorial development of antibacterial Zr-Cu-Al-Ag thin film metallic glasses

PubMed Central

Liu, Yanhui; Padmanabhan, Jagannath; Cheung, Bettina; Liu, Jingbei; Chen, Zheng; Scanley, B. Ellen; Wesolowski, Donna; Pressley, Mariyah; Broadbridge, Christine C.; Altman, Sidney; Schwarz, Udo D.; Kyriakides, Themis R.; Schroers, Jan

2016-01-01

Metallic alloys are normally composed of multiple constituent elements in order to achieve integration of a plurality of properties required in technological applications. However, conventional alloy development paradigm, by sequential trial-and-error approach, requires completely unrelated strategies to optimize compositions out of a vast phase space, making alloy development time consuming and labor intensive. Here, we challenge the conventional paradigm by proposing a combinatorial strategy that enables parallel screening of a multitude of alloys. Utilizing a typical metallic glass forming alloy system Zr-Cu-Al-Ag as an example, we demonstrate how glass formation and antibacterial activity, two unrelated properties, can be simultaneously characterized and the optimal composition can be efficiently identified. We found that in the Zr-Cu-Al-Ag alloy system fully glassy phase can be obtained in a wide compositional range by co-sputtering, and antibacterial activity is strongly dependent on alloy compositions. Our results indicate that antibacterial activity is sensitive to Cu and Ag while essentially remains unchanged within a wide range of Zr and Al. The proposed strategy not only facilitates development of high-performing alloys, but also provides a tool to unveil the composition dependence of properties in a highly parallel fashion, which helps the development of new materials by design. PMID:27230692

First-Principles Study of the Jahn-Teller Distortion in the Ti1-XVXH2 and Zr1-XNbxH2 Alloys

NASA Astrophysics Data System (ADS)

Quijano, Ramiro; de Coss, Romeo; Singh, David

2008-03-01

The transition metal dihydrides TiH2 and ZrH2 present the fluorite structure (CaF2) at high temperature but undergoes a tetragonal distortion with c/a<1 at low temperature. Electronic band structure calculations have shown that TiH2 and ZrH2 in the cubic phase display a very flat band at the Fermi level. Thus the low temperature tetragonal distortion has been associated to a Jahn-Teller effect. In order to understand the role of band filling in controlling the structural instability of the transition metal dihydrides, we have performed a first-principles total energy study of the Ti1-XVxH2 and Zr1-xNbxH2 alloys. The calculations were performed using FP-LAPW method within the (DFT) and we use the GGA for exchange correlation functional energy. The critical concentration for which the Jahn-Teller effect is suppressed, was determined from the evolution of the tetragonal-cubic energy barrier. We discuss the electronic mechanism of the structural-instability, in terms of the band filling. From the obtained results we conclude that the tetragonal distortion in TiH2 and ZrH2 is not produced only by a Jahn-Teller Effect. This research was supported by Consejo Nacional de Ciencia y Tecnolog'ia (Conacyt) under Grant No. 43830-F.

Mechanical properties and bio-tribological behaviors of novel beta-Zr-type Zr-Al-Fe-Nb alloys for biomedical applications.

PubMed

Hua, Nengbin; Chen, Wenzhe; Zhang, Lei; Li, Guanghui; Liao, Zhenlong; Lin, Yan

2017-07-01

The present study prepares novel Zr 70+x Al 5 Fe 15-x Nb 10 (x=0, 5) alloys by arc-melting for potential biomedical application. The mechanical properties and bio-tribological behaviors of the Zr-based alloys are evaluated and compared with biomedical pure Zr. The as-prepared alloys exhibit a microstructure containing a micrometer-sized dendritic beta-Zr phase dispersed in a Zr 2 Fe-typed matrix. It is found that increasing the content of Zr is favorable for the mechanical compatibility with a combination of low Young's modulus, large plasticity, and high compressive strength. The wear resistance of the Zr-Al-Fe-Nb alloys in air and phosphate buffer saline (PBS) solution is superior to that of pure Zr. The wear mechanism of Zr-based alloys sliding in air is controlled by oxidation and abrasive wear whereas that sliding in PBS is controlled by synergistic effects of the abrasive and corrosive wear. Electrochemical measurements demonstrate that the Zr-based alloys are corrosion resistant in PBS. Their bio-corrosion resistance is improved with the increase in Zr content, which is attributed to the enrichment in Zr and decrease in Al concentration in the surface passive film of alloys. The Zr 75 Al 5 Fe 10 Nb 10 exhibits the best corrosion resistance in PBS, which contributes to its superior wear resistance in a simulated body environment. The combination of good mechanical properties, corrosion resistance, and biotribological behaviors of the Zr-Al-Fe-Nb alloys offers them potential advantages in biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Structure and Infrared Emissivity Properties of the MAO Coatings Formed on TC4 Alloys in K2ZrF6-Based Solution

PubMed Central

Li, Ying; Hu, Dan; Xi, Zhengping

2018-01-01

Micro-arc oxidation (MAO) ceramic coatings were formed on TC4 alloy surface in silicate and metaphosphate electrolytes based with K2ZrF6 for various concentrations. X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) were used to characterize the phase composition, microstructure and chemical compositions of the coatings. The infrared emissivity of the coatings was measured at 50 °C in a wavelength range of 8–20 µm. The microstructural observations all revealed the typical porousstructures. Moreover, adecline in roughness and thickness of the prepared coatings can be observed when the concentration of K2ZrF6 increases. Combined with the results of XRD and XPS, it was found that all the oxides existed as the amorphous form in the coatings except the TiO2 phase. The coatings exhibited the highest infrared emissivity value (about 0.89) when the concentration of K2ZrF6 was 6 g/L, which was possibly attributed to the defect microstructure and the optimal role of ZrO2. PMID:29414841

A comment on the thermal conductivity of (U,Pu)O 2 and (U,Th)O 2 by molecular dynamics with adjustment for phonon-spin scattering

DOE PAGES

Cooper, Michael William D.; Liu, Xiang -Yang; Stanek, Christopher Richard; ...

2016-07-15

In this study, a new approach for adjusting molecular dynamics results on UO 2 thermal conductivity to include phonon-spin scattering has been used to improve calculations on U x Pu 1–x O 2 and U xTh 1xO 2. We demonstrate that by including spin scattering a strong asymmetry as a function of uranium actinide fraction, x, is obtained. Greater degradation is shown for U xTh 1–xO 2 than U xPu 1-xO 2. Minimum thermal conductivities are predicted at U 0.97Pu 0.03O 2 and U 0.58Th 0.42O 2, although the degradation in U xPu 1–xO 2 is negligible relative to puremore » UO 2.« less

Speciation of plutonium and other metals under UREX process conditIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paulenova, Alena; Tkac, Peter; Matteson, Brent S.

2007-07-01

The extractability of various Pu and Np species into tri-n-butyl phosphate (TBP) was investigated. The concentration effects of aceto-hydroxamic acid, nitric acid and nitrate on the distribution ratio of U, Pu and Np were investigated. The considerable ability of AHA to form complexes with the studied elements even under strong acidic conditions was found. While the difference in the extraction of uranyl in the presence and absence of AHA is minimal, extraction yields of Pu and Np decrease significantly. The UV-Vis-NIR and FT-IR spectroscopic investigations of uranium, plutonium, and neptunium species in the presence and absence of AHA in bothmore » aqueous and organic extraction phase were also performed. Spectroscopic analysis showed that the organic phase can contain a substantial amount of metal-hydroxamate species. A solvated ternary complex of uranium UO{sub 2}.AHA.NO{sub 3}.2TBP was observed only after prolonged contact between the aqueous and organic phases, whereas the plutonium hydroxamate species, presumably Pu(AHA){sub x}(NO{sub 3}){sub 4-x}.2TBP, appeared in the organic phase after a four minute extraction. (authors)« less

TiO2, SiO2 and ZrO2 Nanoparticles Synergistically Provoke Cellular Oxidative Damage in Freshwater Microalgae

PubMed Central

Liu, Yinghan; Ye, Nan; Fang, Hao; Wang, Degao

2018-01-01

Metal-based nanoparticles (NPs) are the most widely used engineered nanomaterials. The individual toxicities of metal-based NPs have been plentifully studied. However, the mixture toxicity of multiple NP systems (n ≥ 3) remains much less understood. Herein, the toxicity of titanium dioxide (TiO2) nanoparticles (NPs), silicon dioxide (SiO2) NPs and zirconium dioxide (ZrO2) NPs to unicellular freshwater algae Scenedesmus obliquus was investigated individually and in binary and ternary combination. Results show that the ternary combination systems of TiO2, SiO2 and ZrO2 NPs at a mixture concentration of 1 mg/L significantly enhanced mitochondrial membrane potential and intracellular reactive oxygen species level in the algae. Moreover, the ternary NP systems remarkably increased the activity of the antioxidant defense enzymes superoxide dismutase and catalase, together with an increase in lipid peroxidation products and small molecule metabolites. Furthermore, the observation of superficial structures of S. obliquus revealed obvious oxidative damage induced by the ternary mixtures. Taken together, the ternary NP systems exerted more severe oxidative stress in the algae than the individual and the binary NP systems. Thus, our findings highlight the importance of the assessment of the synergistic toxicity of multi-nanomaterial systems. PMID:29419775

Flow Behavior and Constitutive Equation of Ti-6.5Al-2Sn-4Zr-4Mo-1W-0.2Si Titanium Alloy

NASA Astrophysics Data System (ADS)

Yang, Xuemei; Guo, Hongzhen; Liang, Houquan; Yao, Zekun; Yuan, Shichong

2016-04-01

In order to get a reliable constitutive equation for the finite element simulation, flow behavior of Ti-6.5Al-2Sn-4Zr-4Mo-1W-0.2Si alloy under high temperature was investigated by carrying a series of isothermal compression tests at temperatures of 1153-1293 K and strain rates of 0.01-10.0 s-1 on the Gleeble-1500 simulator. Results showed that the true stress-strain curves exhibited peaks at small strains, after which the flow stress decreased monotonically. Ultimately, the flow curves reached steady state at the strain of 0.6, showing a dynamic flow softening phenomenon. The effects of strain rate, temperature, and strain on the flow behavior were researched by establishing a constitutive equation. The relations among stress exponent, deformation activation energy, and strain were preliminarily discussed by using strain rate sensitivity exponent and dynamic recrystallization kinetics curve. Stress values predicted by the modified constitutive equation showed a good agreement with the experimental ones. The correlation coefficient ( R) and average absolute relative error (AARE) were 98.2% and 4.88%, respectively, which confirmed that the modified constitutive equation could give an accurate estimation of the flow stress for BT25y titanium alloy.

Bio-Diesel Production from Deoxygenation Reaction Over Ce0.6Zr0.4O2 Supported Transition Metal (Ni, Cu, Co, and Mo) Catalysts.

PubMed

Shim, Jae-Oh; Jeong, Dae-Woon; Jang, Won-Jun; Jeon, Kyung-Won; Jeon, Byong-Hun; Kim, Seong-Heon; Roh, Hyun-Seog; Na, Jeong-Geol; Han, Sang Sup; Ko, Chang Hyun

2016-05-01

Ce0.6Zr0.4O2 supported transition metal (Me = Ni, Cu, Co, and Mo) catalysts have been investigated to screen for the catalytic activity and selectivity for deoxygenation reaction of oleic acid. Me-Ce0.6Zr0.4O2 catalysts were prepared by a co-precipitation method. Ni-Ce0.6Zr0.4O2 catalyst exhibited much higher oleic acid conversion, selectivity for C9 to C17 compounds, and oxygen removal efficiency than the others. This is mainly ascribed to the presence of free Ni species, synergy effects between Ni and Ce0.6Zr0.4O2, and the highest BET surface area.

Minimum pickup velocity ( U pu) of nanoparticles in gas-solid pneumatic conveying

NASA Astrophysics Data System (ADS)

Anantharaman, Aditya; van Ommen, J. Ruud; Chew, Jia Wei

2015-12-01

This paper is the first systematic study of the pneumatic conveying of nanoparticles. The minimum pickup velocity, U pu, of six nanoparticle species of different materials [i.e., silicon dioxide (SiO2), aluminum oxide (Al2O3), and titanium dioxide (TiO2)] and surfaces (i.e., apolar and polar) was determined by the weight loss method. Results show that (1) due to relative lack of hydrogen bonding, apolar nanoparticles had higher mass loss values at the same velocities, mass loss curves with accentuated S-shaped profiles, and lower U pu values, (2) among the three species, SiO2, which has the lowest Hamaker coefficient, exhibited the greatest discrepancy between apolar and polar surfaces with respect to both mass loss curves and U pu values, (3) U mf,polar/ U mf,apolar was between 1 and 3.5 times that of U pu,polar/ U pu,apolar due to greater extents of hydrogen bonding associated with U mf, (4) U pu values were at least an order-of-magnitude lower than that expected from the well-acknowledged U pu correlation (Kalman et al., Powder Technol 160:103-113, 2005) due to agglomeration, (5) although nanoparticles should be categorized as Zone III (Kalman et al. 2005) (or Geldart group C, Powder Technol 7:285-292, 1973), the nanoparticles, and primary and complex agglomerates agreed more with the Zone I (or Geldart group B) correlation.

THE DETERMINATION OF TRACES OF BORON IN ZIRCONIUM METAL AND ZIRCONIUM ALLOYS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayes, M.R.; Metcalfe, J.

1962-01-01

A general procedure is given for the determination of B, down to 0.2 ppm, in Zr and Zr alloys. Separation of the B is not necessary, the B-curcumin complex being formed directly in an aliquot of the metal sulfate solution. An interference effect has been noted when analyzing Zr alloys containing Sn. The interference is caused by an insoluble compound of curcumin which separates and has similar properties to the B-curcumin complex. This source of interference is, however, readily eliminated during the procedure for the determination of B. The procedure has been applied to the determination of B in puremore » Zr, zr--0.5% Cu-- 0.5% MO, and Zr--1.5% Sn--0.1% Fe--0.1% Cr--0.05% Ni alloys. Results are comparable with those obtained by methods requiring the separation of the B as methyl borate. (auth)« less

Enhancement of wear and corrosion resistance of low modulus β-type Zr-20Nb-xTi (x=0, 3) dental alloys through thermal oxidation treatment.

PubMed

Zhang, Jianfeng; Gan, Xiaxia; Tang, Hongqun; Zhan, Yongzhong

2017-07-01

In order to obtain material with low elastic modulus, good abrasion resistance and high corrosion stability as screw for dental implant, the biomedical Zr-20Nb and Zr-20Nb-3Ti alloy with low elastic modulus were thermal oxidized respectively at 700°C for 1h and 600°C for 1.25h to obtain the compact oxidized layer to improve its wear resistance and corrosion resistance. The results show that smooth compact oxidized layer (composed of monoclinic ZrO 2 , tetragonal ZrO 2 and 6ZrO 2 -Nb 2 O 5 ) with 22.6μm-43.5μm thickness and 1252-1306HV hardness can be in-situ formed on the surface of the Zr-20Nb-xTi (x=0, 3). The adhesion of oxidized layers to the substrates is determined to be 58.35-66.25N. The oxidized Zr-20Nb-xTi alloys reveal great improvement of the pitting corrosion resistance in comparison with the un-oxidized alloys. In addition, the oxidized Zr-20Nb-3Ti exhibits sharply reduction of the corrosion rates and the oxidized Zr-20Nb shows higher corrosion rates than un-oxidized alloys, which is relevant with the content of the t-ZrO 2 . Wear test in artificial saliva demonstrates that the wear losses of the oxidized Zr-20Nb-xTi (x=0, 3) are superior to pure Ti. All of the un-oxidized Zr-20Nb-xTi (x=0, 3) alloys suffer from serious adhesive wear due to its high plasticity. Because of the protection from compact oxide layer with high adhesion and high hardness, the coefficients of friction and wear losses of the oxidized Zr-20Nb-xTi (x=0, 3) alloys decrease 50% and 95%, respectively. The defects on the oxidized Zr-20Nb have a negative effect on the friction and wear properties. In addition, after the thermal oxidation, compression test show that elastic modulus and strength of Zr-20Nb-xTi (x=0, 3) increase slightly with plastic deformation after 40% of transformation. Furthermore, stripping of the oxidized layer from the alloy matrix did not occur during the whole experiments. As the surface oxidized Zr-20Nb-3Ti alloy has a combination of excellent performance

Specific Volumes of the Zr(41.2)Ti(13.8)Cu(12.5)Ni(10.0)Be(22.5) Alloy in the Liquid, Glass, and Crystalline States

NASA Technical Reports Server (NTRS)

Ohsaka, K.; Chung, S. K.; Rhim, W. K.; Johnson, W. L.; Peker, A.; Scruggs, D.

1997-01-01

The specific volumes of the Zr(41.2)Ti(3.8)Cu(2.5)Ni(10.0)Be(22.5) alloy as a function of temperature, T, are determined by employing an image digitizing technique and numerical calculation methods applied to the electrostatically levitated spherical alloy. The linear fitting of the volumes of the alloy in the liquid, V(sub l), glass, V(sub g) and crystalline V(sub c), states in the temperature ranges shown in parentheses are V(sub l)(T) = 0.1583 + 8.877 x 10(exp -6) T(cu cm/g) (700-1300 K);V(sub g)(T) = 0.1603 + 5.528 x 10(exp -6) T (400-550 K);V(sub c)(T) = 0.1583 + 6.21 x 10(exp -6)T(400-850 K). The average volume thermal expansion coefficients within the temperature ranges are determined to be 5.32, 3.39. and 3.83 x 10(exp -5) (1/K) for the liquid, glass, and crystalline states, respectively.

On the Potential of Bulk Metallic Glasses for Dental Implantology: Case Study on Ti40Zr10Cu36Pd14.

PubMed

Liens, Alethea; Etiemble, Aurélien; Rivory, Pascaline; Balvay, Sandra; Pelletier, Jean-Marc; Cardinal, Sandrine; Fabrègue, Damien; Kato, Hidemi; Steyer, Philippe; Munhoz, Tais; Adrien, Jerome; Courtois, Nicolas; Hartmann, Daniel J; Chevalier, Jérôme

2018-02-06

Ti 40 Zr 10 Cu 36 Pd 14 Bulk Metallic Glass (BMG) appears very attractive for future biomedical applications thanks to its high glass forming ability, the absence of toxic elements such as Ni, Al or Be and its good mechanical properties. For the first time, a complete and exhaustive characterization of a unique batch of this glassy alloy was performed, together with ISO standard mechanical tests on machined implant-abutment assemblies. The results were compared to the benchmark Ti-6Al-4V ELI (Extra-Low-Interstitial) to assess its potential in dental implantology. The thermal stability, corrosion and sterilization resistance, cytocompatibility and mechanical properties were measured on samples with a simple geometry, but also on implant-abutment assemblies' prototypes. Results show that the glassy alloy exhibits a quite high thermal stability, with a temperature range of 38 °C between the glass transition and crystallization, a compressive strength of 2 GPa, a certain plastic deformation (0.7%), a hardness of 5.5 GPa and a toughness of 56 MPa.√m. Moreover, the alloy shows a relatively lower Young's modulus (96 GPa) than the Ti-6Al-4V alloy (110-115 GPa), which is beneficial to limit bone stress shielding. The BMG shows a satisfactory cytocompatibility, a high resistance to sterilization and a good corrosion resistance (corrosion potential of -0.07 V/SCE and corrosion current density of 6.0 nA/cm²), which may ensure its use as a biomaterial. Tests on dental implants reveal a load to failure 1.5-times higher than that of Ti-6Al-4V and a comparable fatigue limit. Moreover, implants could be machined and sandblasted by methods usually conducted for titanium implants, without significant degradation of their amorphous nature. All these properties place this metallic glass among a promising class of materials for mechanically-challenging applications such as dental implants.

Containerless Measurement of Thermophysical Properties of Ti-Zr-Ni Alloys

NASA Technical Reports Server (NTRS)

Hyers, Robert; Bradshaw, Richard C.; Rogers, Jan C.; Rathz, Thomas J.; Lee, Geun W.; Gangopadhyay, Anup K.; Kelton, Kenneth F.

2004-01-01

The surface tension, viscosity, density, and thermal expansion of Ti-Zr-Ni alloys were measured for a number of compositions by electrostatic levitation methods. Containerless methods greatly reduce heterogeneous nucleation, increasing access to the undercooled liquid regime at finite cooling rates. The density and thermal expansion are measured optically, while the surface tension and viscosity are measured by the oscillating drop method. The measured alloys include compositions which form a metastable quasicrystal phase from the undercooled liquid, and alloys close to the composition of several multi-component bulk metallic glass-forming alloys. Measurements of surface tension show behavior typical of transition metals at high temperature, but a sudden decrease in the deeply undercooled liquid for alloys near the quasicrystal-forming composition range, but not for compositions which form the solid-solution phase first.

Stabilizing stored PuO2 with addition of metal impurities

NASA Astrophysics Data System (ADS)

Moten, Shafaq; Huda, Muhammad

Plutonium oxides is of widespread significance due its application in nuclear fuels, space missions, as well as the long-termed storage of plutonium from spent fuel and nuclear weapons. The processes to refine and store plutonium bring many other elements in contact with the plutonium metal and thereby affect the chemistry of the plutonium. Pure plutonium metal corrodes to an oxide in air with the most stable form of this oxide is stoichiometric plutonium dioxide, PuO2. Defects such as impurities and vacancies can form in the plutonium dioxide before, during and after the refining processes as well as during storage. An impurity defect manifests itself at the bottom of the conduction band and affects the band gap of the unit cell. Studying the interaction between transition metals and plutonium dioxide is critical for better, more efficient storage plans as well as gaining insights to provide a better response to potential threats of exposure to the environment. Our study explores the interaction of a few metals within the plutonium dioxide structure which have a likelihood of being exposed to the plutonium dioxide powder. Using Density Functional Theory, we calculated a substituted metal impurity in PuO2 supercell. We repeated the calculations with an additional oxygen vacancy. Our results reveal interesting volume contraction of PuO2 supercell when one plutonium atom is substituted with a metal atom. The authors acknowledge the Texas Computing Center (TACC) at The University of Texas at Austin and High Performance Computing (HPC) at The University of Texas at Arlington.

Measurements of Pu and Ra isotopes in soils and sediments by AMS

NASA Astrophysics Data System (ADS)

Tims, S. G.; Hancock, G. J.; Wacker, L.; Fifield, L. K.

2004-08-01

Plutonium fallout from atmospheric nuclear weapons testing in the 1950s and 1960s constitutes an artificial tracer suitable for the study of recent soil erosion and sediment accumulation rates. Long-lived Pu isotopes provide an alternative tracer to the more widely used 137Cs (t1/2=30 a), the concentration of which is decaying at a rate that will limit its long-term application to these studies. For 239,240Pu, the sensitivity of AMS is more than an order of magnitude better than that afforded by α-spectroscopy. Furthermore, AMS can provide a simple, direct measure of the 240Pu/239Pu ratio. Sample profiles from two sites along eastern Australia have been determined with both AMS and α-spectroscopy to provide comparative measurements of the sediment accumulation rate in water bodies and of the soil erosion rate. The two methods are in good agreement. The 228Ra/226Ra ratio potentially provides a probe for tracing the dispersion of uranium mining residues into the neighboring environment. Soil depth profiles of the ratio may provide information on the rate at which mining-derived radioactivity is spread by surface waters, and could be used to assess the effectiveness of remediation and rehabilitation technologies. AMS offers several advantages over the more usual α- and γ-spectroscopy techniques in that it can directly and quickly measure both isotopes in a sample of small size and with simple sample preparation. We show that AMS can be used to measure these isotopes of radium at the sensitivity required for environmental samples using RaC2- as the injected beam species.

Identification of phases in the interaction layer between U-Mo-Zr/Al and U-Mo-Zr/Al-Si

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varela, C.L. Komar; Arico, S.F.; Mirandou, M.

Out-of-pile diffusion experiments were performed between U-7wt.% Mo-1wt.% Zr and Al or Al A356 (7,1wt.% Si) at 550 deg. C. In this work morphological characterization and phase identification on both interaction layer are presented. They were carried out by the use of different techniques: optical and scanning electron microscopy, X-Ray diffraction and WDS microanalysis. In the interaction layer U-7wt.% Mo-1wt.% Zr/Al, the phases UAl{sub 3}, UAl{sub 4}, Al{sub 20}Mo{sub 2}U and Al{sub 43}Mo{sub 4}U{sub 6} were identified. In the interaction layer U-7wt.% Mo-1wt.% Zr/Al A356, the phases U(Al, Si) with 25at.% Si and Si{sub 5}U{sub 3} were identified. This lastmore » phase, with a higher Si concentration, was identified with XRD Synchrotron radiation performed at the National Synchrotron Light Laboratory (LNLS), Campinas, Brasil. (author)« less

Some properties of low-vapor-pressure braze alloys for thermionic converters

NASA Technical Reports Server (NTRS)

Bair, V. L.

1978-01-01

Density, dc electrical resistivity, thermal conductivity, and linear thermal expansion are measured for arc-melted rod-shaped samples of binary eutectics of Zr, Hf, Ru, Nb, Ir, Mo, Ta, Os, Re, and W selected as very-low-pressure braze fillers for thermionic converters. The first two properties are measured at 296 K for Zr-21.7 at% Ru, Zr-13 wt% W, Zr-19 wt% W, Zr-22.3 at% Nb, Nb-66.9 at% Ru, Hf-25.3 wt% Re, Zr-25.7 at% Ta, Hf-22.5 at% W, and Nb-35 wt% Mo. The last property is measured from 293 K to 2/3 melting point for specified alloys of different compositions. Resistivities of 0.000055 to 0.000181 ohm-cm are observed with the alloys having resistivities about ten times that of the less resistive constituent metal and about three times that of the more resistive constituent metal, except for Zr-19 wt% W and Nb-35 wt% Mo (greater resistivities). Thermal expansion coefficients vary from 0.000006 to 0.0000105/K. All brazes exhibit linear thermal expansion near that of their constituent metals.

Changes in the state of iron atoms in Zr alloys during corrosion tests in an autoclave

NASA Astrophysics Data System (ADS)

Filippov, V. P.; Bateev, A. B.; Lauer, Yu. A.; Kargin, N. I.; Petrov, V. I.

2014-04-01

Mössbauerinvestigations were carried out on oxide films formed on specimens of zirconium alloys Zr-1.0 %wtFe-1.2 %wtSn-0.5 %wtCr subjected to corrosion in steam-water environment at a temperature of 360 °C and at a pressure of 16.8 MPa with lithium and boron additions, and on Zr-1.4 %wtFe-0.7 %wtCr corroded in steam-water environment at 350 °C and 16.8 MPa as well as in steam-water environment at 500 °C and 10 MPa. In the metal part of the samples, under the oxide film, the iron atoms are in form of intermetallic precipitates of Zr(Fe, Cr)2. The corrosion process decomposes the intermetallic precipitates and particles are formed of metallic iron with inclusions of chromium atoms -Fe(Cr), α-Fe2O3 and Fe3O4 compounds. Part of the iron ions are in divalent and part in trivalent paramagnetic states. It is proposed that some part of the iron containing oxide precipitates in the oxide film may be in the form of nanoparticles which pass from the superparamagnetic to the ferromagnetic state with decreasing temperature.

Development of Cu Clad Cu-Zr Based Metallic Glass and Its Solderability

NASA Astrophysics Data System (ADS)

Terajima, Takeshi; Kimura, Hisamichi; Inoue, Akihisa

Soldering is a candidate technique for joining metallic glasses. It can be processed far below the crystallization temperatures of the various metallic glasses so that there is no possibility of crystallization. However, wettability of Cu-Zr based metallic glass by Pb free solder is poor because a strong surface oxide film interferes direct contact between them. To overcome the problem, Cu thin film clad metallic glass was developed. It was preliminary produced by casting a melt of Cu36Zr48Al8Ag8 pre-alloy into Cu mold cavity, inside which Cu thin film with 2 mm in thickness was set on the wall. Cu36Zr48Al8Ag8 metallic glass, whose surface Cu thin film was welded to, was successfully produced. From the microstructure analyses, it was found that reaction layer was formed at the interface between Cu and Cu36Zr48Al8Ag8 metallic glass, however, there was no oxide in the Cu clad layer. Solderability to the metallic glass was drastically increased. The Cu clad layer played an important role to prevent the formation of surface oxide film and consequently improved the solderability.

Bio-corrosion and cytotoxicity studies on novel Zr 55Co 30Ti 15 and Cu 60Zr 20Ti 20 metallic glasses

DOE PAGES

Vincent, S.; Daiwile, A.; Devi, S. S.; ...

2014-09-26

Metallic glasses are a potential and compatible implant candidate for biomedical applications. In the present investigation, a comparative study between novel Zr 55Co 30Ti 15 and Cu 60Zr 20Ti 20 metallic glasses is carried out to evaluate in vitro biocompatibility using simulated body fluids. The bio-corrosion behavior of Zr- and Cu-based metallic glasses in different types of artificial body fluids such as artificial saliva solution, phosphate-buffered saline solution, artificial blood plasma solution, and Hank’s balanced saline solution is evaluated using potentiodynamic polarization studies at a constant body temperature of 310.15 K (37 °C). Surface morphology of samples after bio-corrosion experimentsmore » was observed by scanning electron microscopy. In vitro cytotoxicity test on glassy alloys were performed using human osteosarcoma cell line as per 10993-5 guidelines from International Organization for Standardization. As a result, the comparative study between Zr- and Cu-based glassy alloys provides vital information about the effect of elemental composition on biocompatibility of metallic glasses.« less

Evaluation of phases in Pu-C-O and (U, Pu)-C-O systems by X-ray diffractometry and chemical analysis

NASA Astrophysics Data System (ADS)

Jain, G. C.; Ganguly, C.

1993-12-01

Preparation and characterisation of the carbides of uranium, plutonium and mixed uranium and plutonium form a part of advanced fuel development programs for fast breeder reactors. In the present study, the compositions of the phases of Pu-C-O and (U.Pu)-C-O systems have been determined by chemical analysis and lattice parameter measurement. The carbide samples have been prepared by vacuum carbothermic synthesis of tabletted oxide-graphite powder mixture. Dependence of stoichiometry of Pu 2C 3 phase on the oxygen content of Pu(C,O) phase in Pu(C,O) + Pu 2C 3 phase mixture has been evaluated. Stoichiometry and oxygen solubility of (U 0.3Pu 0.7)(C,O) phase in multiple phase mixture have been determined. Segregation of plutonium in (U,Pu) 2C 3 phase of (U,Pu)(C,O) + (U,Pu) 2C 3 phase mixture and its dependence on the oxygen content of (U,Pu)(C,O) phase have also been determined from the measurement of the lattice parameter of (U,Pu) 2C 3 phase.

Electrochemical Behavior Assessment of As-Cast Mg-Y-RE-Zr Alloy in Phosphate Buffer Solutions (X Na3PO4 + Y Na2HPO4) Using Electrochemical Impedance Spectroscopy and Mott-Schottky Techniques

NASA Astrophysics Data System (ADS)