bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preliminary Results of Laboratory Studies of Repository Chemistry for the Waste Isolation Pilot Plant
Authors: Brush L. H. , Grbic-Galic D. , Reed D. T. , Tong X. , Vreeland R. H. , Westerman R. E. 
Published: March 2011

ABSTRACTThe design-basis, defense-related, transuranic (TRU) waste to be emplaced in the Waste Isolation Pilot Plant (WIPP) could, if sufficient H2O and nutrients were present, produce as much as 1,500 moles of gas per drum of waste. Gas production could pressurize the repository to lithostatic pressure (150 atm) and perhaps higher.Anoxic corrosion of Fe and Fe-base alloys and microbial degradation of cellulosics are the processes of greatest concern, but radiolysis of brine could also be important. The proposed backfill additives CaC03, CaO, CuSO4, KOH, and NaOH may remove or prevent the production of some of the expected gases. We describe these processes and present preliminary results of laboratory studies of anoxic corrosion and microbial activity.
Parametric Investigation of Rock Salt Behaviour Resulting from Disposal of High Level Radioactive Waste
Authors: Caramelle D. , Gaudez M.T. , Monig J. , Ouzounian G. , Simonet G. 
Published: March 2011

ABSTRACTThe liberation and generation of gases from rock salt due to heat and gamma irradiation is investigated in order to obtain some of the data needed for the development of the concept for the disposal of high level waste in rock salt.Our work is concerned with the influence of various parameters on gas production, e.g. salt composition and grain size, total absorbed dose, dose rate, temperature and gas atmosphere. Some of these parameters have not been studied previously in detail.The original gamma irradiator employing spent fuel elements and capable of exposing samples at temperatures up to 250°C will be described. Experimental results from some 150 experiments will be given. The two major gases found were CO2 and N2O.CO, H2, CH4, Hydrocarbons, CI2, HCl and SO2 were also detected. The dependence of the gas yields on the various parameters will be presented and discussed.
A Review Process and a Database for Waste-Package Documents
Authors: Interrante Charles G. , Messina Carla A. , Fraker Anna C. 
Published: March 2011

ABSTRACTThe work reported here is part of a program conducted by the Nuclear Regulatory Commission on the efficacy of proposed plans for radionuclide containment for long-term storage of high-level nuclear waste (HLW). An important element of that program is the review and evaluation of available literature on components of a waste package. A review process and a database have been developed and tailored to provide information quickly to an individual who has a question about a particular material or component of a waste package. The database is uniquely suited to serve as a guide to indicate special areas where data and information needs exist on questions related to radionuclide containment. Additions to the database are made as information becomes available, and this source is as current as the published literature. A description of the review process and the database is given.
Effects of Alpha and Gamma Radiation on Glass Reaction in an Unsaturated Environment
Authors: Wronkiewicz David J. , Young John E. , Bates John K. 
Published: March 2011

ABSTRACTRadiation may effect the long-term performance of glass in an unsaturated repository site by interacting with air, water vapor, or liquid water. The present study examines (1) the effects of alpha or gamma irradiation in a water vapor environment, and (2) the influence of radiolytic products on glass reaction. Results Indicate that nitric and organic acids form in an irradiated water vapor environment and are dissolved in thin films of condensed water. Glass samples exposed to these conditions react faster and have a different assemblage of secondary phases than glasses exposed to nonirradiated water vapor environments.
Microstructure and Properties of Eutectic Composites Based on (Ti, Nb)3 (Al, Si) and (Ti, Nb)5 (Si, Al)3
Authors: Wagner R. , Es-Souni M. , Chen D. , Dogan B. , Seeger J. , Beaven P. A. 
Published: March 2011

ABSTRACTPrevious work has shown that ternary Ti-Al-Si alloys with hypoeutectic and eutectic microstructures containing the intermetallic phases Ti3 (Al,Si) and Ti5 (Si,Al)3 have promising high temperature mechanical properties [1]. In the present investigation alloying additions of Niobium have been made to selected Ti-Al-Si alloys based on hypoeutectic compositions and the effects of Niobium on the microstructure and mechanical properties have been studied. The high temperature creep and oxidation behaviour of such alloys appears to be superior to that of currently available Ti3Al-based alloys.
First-Principles Calculations of Phase Stability for High Temperature Intermetallics
Authors: Becker J.D. , Sanchez J.M. , Tien J.K. 
Published: March 2011

ABSTRACTTotal energy electronic structure calculations are performed for the elements and selected binary ordered compounds of the ternary system Nb-Ru-Zr. These calculations provide binding energies, atomic volumes, bulk moduli, Debye temperatures, and Grüneiesen constants for the selected structures and compounds. Volume dependent pair and many-body chemical interactions are also obtained from the total energy results which, in turn, are used to study partially ordered alloys at finite temperatures. The stability of all the binary intermetallic compounds experimentally observed at low temperatures is correctly predicted by the first-principles calculations. The solid state portion of the Nb-Ru binary phase diagram is calculated using the chemical interactions obtained from the total energy calculations, a Debye-Grüneisen model for the vibrational free energy and the cluster variation method (CVM) for the configurational entropy with a local volume relaxation scheme. The calculations reproduce the experimentally observed ordering temperature of the NbRu3 intermetallic to within 2%.
First Principles Calculation of Phase Stability of High Temperature Intermetallic Alloys
Authors: Mikalopas J. , Sterne P.A. , Sluiter M. , Turchi P.E.A. 
Published: March 2011

ABSTRACTOne way to calculate the coherent phase diagram of an alloy based on first principles methods is to compute the ground state total energy for various ordered configurations, from which many-body interactions can be calculated and employed in a thermodynamic model. If the Connolly and Williams method (CWM) is used to extract the many-body interactions from the calculated total energies, the resulting many-body interactions can exhibit a strong dependence on the choice of ordered configurations and multi-site clusters, and the accuracy and convergence of the CWM energy expansion is not assured. To overcome this difficulty, a successful systematic method for implementing the CWM is proposed. This approach is applied to a study of the fcc-based Ni-V and Pd-V substitutional alloys and these interaction parameters together with the cluster variation method (CVM) are used to calculate phase diagrams.
Relation of Phase Stability Boundary to the Fill-Up Bonding States In Ni3V,Co3V and Fe3V
Authors: Lin W. , Xu Jian-Hua , Freeman A.J. 
Published: March 2011

ABSTRACTThe electronic structures and cohesive properties of the intermetallics Ni3V, Co3V, and Fe3V in the L12 structure have been studied using the self-consistent total energy linear muffin-tin orbital method based on the local density approximation. The simple rigid-band concept appears to be adequate to explain the structural stability of these compounds. Further,the structural stability of the pseudobinary compounds (Ni,Co,Fe)3V has been investigated based on the rigid-band scheme. The correlation between the electronic concentration and the crystal structure is shown to be related to the fill-up of the bonding states.
Computer Simulation of the Elastic Energy Contribution to Antiphase Boundary Energy Anisotropy
Authors: Van Der Heide Robert G. , Allen Samuel M. 
Published: March 2011

ABSTRACTThe results of computer simulations on the effect of elastic energy on APB anisotropy are presented. The model used treats composition and order parameter as local variables defined at crystal planes parallel to the APB. The set that minimizes the free energy, including elastic energy terms, defines the equilibrium APB structure. It was found that, despite their high elastic anisotropy, elastic effects would not result in any substantial APB anisotropy in Fe-Al alloys. However, a model with different parameters did show a high degree of anisotropy.
A Model for the Yield Behavior of Ni3Ai Alloys
Authors: de Bussac Arnaud , Webb Graham , Antolovich Stephen D. 
Published: March 2011

ABSTRACTCurrent models for predicting the unusual deformation characteristics of Ni3Al alloys are based upon the idea of cross-slip pinning of screw dislocation segments. These models assume an Arrhenius type framework which employs a stress-modified activation barrier for forward cross slip. Use of such models has been successful in describing the orientation, asymmetry and temperature characteristics of yielding. A limitation of current models is their inability to predict the apparent lack of a strain rate effect in Ni3Al alloys. The current model approaches the problem using both kinetic and thermodynamic arguments to describe the physical process. It is then demonstrated that the driving force for cross-slip controls the process. The model describes all aspects of deformation including apparent strain rate insensitivity. An additional feature of the model is its ability to provide analytical and physical justification for the use of Arrhenius type equations for representing experimental data.
A Mechanism of the Positive Temperature Dependence of Yield Stress in Tial
Authors: Kawabata T. , Kanai T. , Izumi O. 
Published: March 2011

ABSTRACTThe positive temperature dependence of yield stress (PTYS) has been observed (Kawabata et al., Acta Metall., 33, 1355 (1985)) in TiAl single crystals in all orientations operating ordinary dislocations with the Burgers vector 1/2<110] and superdislocations with the Burgers vectors <101] and 1/2<112]. A mechanism for the PTYS is proposed, which is a cross-slip and pinning mechanism of Shockley partials with the Burgers vector 1/6<112] or/and 1/6<121]. The results of strain rate dependence of yield stress, K value dependence of critical resolved shear stress (CRSS) and transmission electron microscopy support the theory. Here, K value is the Schmid factor ratio of a Shockley partial on {101) or {110) plane and a perfect ordinary dislocation or a perfect superdislocation on {111) plane.
Dislocation Structure in Single Crystal L1o Type Ti-Al-V Compound
Authors: Hahn Y.D. , Li Z.X. , Whang S.H. , Kawabata T. 
Published: March 2011

ABSTRACTSingle Crystals of L1o type Ti44Al54V2 alloy were deformed at high temperatures and various orientations. The dislocations thus produced by single slip were studied by TEM. 1/2<110] dislocations produced at 1073 K consist of dislocation loops and curled dislocations with spiral segments, which is in agreement with those shown in the polycrystalline Ti-Al-V, and -Nb alloys deformed under the same conditions. The normal dislocations produced at 873 K pile up in groups, each of which contains several straight dislocations with a screw character. On the other hand, the majority of superdislocations produced at 873 K were found in a dipole form, indicating that the dipole is a favorable configuration at this temperature.
Dislocations with Non-Planar Locked Structures in the L12Ordered Alloys
Authors: Sun Y.Q. , Hazzledine P.M. , Crimp M.A. 
Published: March 2011

ABSTRACTIn the L12structure, the Kear-Wilsdorf lock on screw superdislocations is the best known example of a dislocation with a non-planar locked structure. Recent high resolution TEM work on Ni3Al and Ni3Ga has shown locked structures on the following dislocations: 30-degree <112>/3 super-Shockley partials, edge <110> {001} dislocations, and 45-degree <100>{001} dislocations. Dislocation reactions among intersecting <100>{001} and <110>{001} slip systems have also been found to form product dislocations with locked structures. This paper summarizes these locked structures and outlines their effects on the operation of related slip systems.
A Tem Study of the Dislocation Structure in a Ni3Al-Based Alloy at Temperatures Below the Peak in Flow Stress
Authors: Wen Mao , Lin Dongliang 
Published: March 2011

ABSTRACTDislocation structure in a directionally solidified Ni3Al-based alloy deformed at temperatures below the peak in flow stress has been studied by the weak beam TEM technique. At room temperature, the screw superdislocations are partly transformed into Kear-Wilsdorf configurations. With increasing temperatures, the transformed Kear-Wilsdorf parts increase until the temperature reaches 450°C, at which the screw superdislocations are wholly transformed. Bending of the Kear-Wilsdorf configurations on {0101} planes is observed at 450°C, which is believed to be the cause of interaction of Kear-Wilsdorf configurations with superkinks. The Contribution of superkink motion to deformation is discussed. The results suggest that deformation in this temperature range occurs primarily by the slip of non-screw components on {lll} planes, which is consistent with the widely accepted cross slip pinning model.
Micromechanisms of Deformation and Fracture in Rapidly Solidified Ni3Al Alloys
Authors: Liu G. , Bond G.M. 
Published: March 2011

ABSTRACTRapidly solidified Ni76 Al24 ribbons, with and without boron, have been the subject of in-situ TEM deformation studies, as well as X-ray and TEM characterization and TEM fractography. The aim has been to gain a better understanding of the influence of a reduced degree of order on grainboundary behavior and ductility. This, in turn, allows fresh insights to be gained, both into the manner in which boron additions can enhance ductility, and into the potential usefulness of sequential ordering in intermetallic alloys with a tendency to intergranular failure. Lower degrees of order are found to reduce stress concentrations at grain boundaries; this effect is due to easier generation of dislocations from boundary sources, and, to a lesser extent, the braking action of thermal APB's on dislocation motion. The beneficial effect of boron on ductility is seen to result, at least in part, from enhanced boundary cohesive strength.
Dislocations Microstructures and Disorientation of Cubic Planes in Samples of a Superalloy Submitted to Bending Tests
Authors: Buffiere J.Y. , Ignat M. , Bastie P. 
Published: March 2011

ABSTRACTSingle crystal samples of a nickel base superalloy have been deformed by cyclic bending tests. At the higher temperatures of our experiments, an evolution of the apparent modulus as the advancement of disorientation of cubic planes has been detected.The dislocation microstructures show that the development of dislocation networks is more advanced in the compressive zones than in the tensile ones.
Effects of Alloying Additions on Intergranular Fracture of Ordered Intermetallics
Authors: Takasugi Takayuki 
Published: March 2011

ABSTRACTThe majority of ordered intermetallics generally exhibit brittle fracture and poor ductility at ambient temperatures, and their brittleness is strongly associated with grain boundary properties. Recent efforts on alloying approaches and microstructural modifications gave promising results to improve the ductility of ordered intermetallics. This article summarizes recent studies on understanding the intergranular brittle fracture from the point of view of compositional and resultant structural (and electro-chemical) properties of grain boundaries. Significant improvement in ductility has been established by the control of chemical composition, that is, by the selection of constituent elements, the control of alloy stoichiometry, the addition of substitutional elements, the change of degree of ordering and the doping by the interstitial elements. Also, the gaseous atoms hydrogen and oxygen from environment or as residue are shown to strongly affect the grain boundary fracture behaviour. Emphasis will be placed on the L12-type ordered intermetallics including Ni3Al, Ni3Si and Co3Ti.
Mechanical Properties of Fe-Modifie Ll2-Type Al3Ti
Authors: Inoue H. R. P. , Cooper C. V. , Favrow L. H. , Hamada Y. , Wayman C. M. 
Published: March 2011

ABSTRACTThe room temperature ductility of an L12-type A13Ti alloy containing 7.5 at.% Fe has been improved substantially by hot isostatic pressing (HIP) after arc casting. This L12-type alloy can be deformed in compression to 11.4 % at room temperature after HIPing, retaining the original shape of compressive specimens, while compressive specimens without HIPing following heat-treatment for homogenization (HHT) fracture into small pieces when deformed to similar strain. At temperatures higher than 400°C, specimens for both HHTed and HIPed conditions show similar behavior, having strains to failure of greater than 12 % plastic strain. Fracture occurs at room temperature by brittle transgranular cleavage with a smooth surface in HHTed specimens, while in HIPed specimens, fracture occurs by both transgranular and intergranular modes. Transgranularly fractured surfaces in the latter case have rough surfaces with fine structure, indicating ductile fracture as compared with that for HHTed specimens. In both HIPed and HHTed specimens, no fracture surfaces are flat and parallel to any crystallographic planes. High resolution electron microscopy has revealed that a pair of superlattice partial dislocations on a (111) plane have a spacing of approximately 11 nm (2–3 times larger than that for Al-23Ti-6Fe-5V) giving an antiphase boundary energy of 95 mJ/m2. Since this energy is relatively low, the present alloy may be ductile because of its ready emission of dislocations at crack tips, according to the Rice-Thomson criterion. Improvement of room-temperature ductility of this alloy is attributed primarily to the reduction of a large population of cavities formed upon arc casting.
Free Energy Simulation of Grain Boundary Segregation and Thermodynamics In Ni3−xAl1+x
Authors: Najafabadi R. , Wang H. Y. , Srolovitzt D. J. , LeSar R. 
Published: March 2011

ABSTRACTThe free energy simulation method is employed to study segregation to Σ5 and Σ13 (001) twist grain boundaries and their free energies in ordered Ni3−xAl1+x. In the temperature range studied (300–900K), it is shown that there is almost no segregation, strong Al segregation, and weak Ni segregation to the grain boundary for the stoichiometric, Al-rich, and Ni-rich bulk compositions respectively. It is also shown that the segregation is limited to a few (002) planes around the grain boundary and its magnitude decreases with increasing temperature. For Al-rich bulk composition, it is demonstrated that segregation at low temperature substantially lowers the grain boundary free energy.
The Effects of Alloy Addittons of Si and Transitton Metal Elements on the Mechanical Properties Of B-Doped Ds Ni3Al
Authors: Zhang Yun , Lin(T.L.Lin) Dongliang 
Published: March 2011

ABSTRACTThe temperature dependence of the flow stress in the B-doped DS Ni3Al containing Si as well as transition metal elements was systematically investigated by tensile tests. The effects of the alloy elements on the magnitude of the positive temperature dependence of the flow stress were evaluated. The calculated activation energy which results in the anomalous mechanical behavior the Ni3Al decreases for each element addition. The flow stress near liquid nitrogen temperature, taken as a measure of the degree of solid solution strengthening, increases linearly with the element concentration. The influences of the element additions on the solid solution strengthening were discussed. Also discussed were the mechanisms of the anomalous mechanical behavior in the Ni3 Al affected by the element additions.
The Effect of Strain Rate on the Mechanical Properties of Single Crystal NiAl
Authors: Lahrman D.F. , Field R.D. , Darolia R. 
Published: March 2011

ABSTRACTIn this study, the strain rate sensitivity of single crystal NiAl has been investigated by performing tensile tests as a function of temperature and two strain rates. Three crystallographic orientations, [100], [110], and [111] were studied. The tensile test results investigated include yield strength, work hardening rate and plastic strain to failure. The data are discussed in terms of deformation mechanisms in NiAl.
Effect of Boron Content on Mechanical Properties of Monocrystalline Ni3Al
Authors: Jianting Guo , Chao Sun , Hui Li , Zhiya Zhang , Yajun Tang , Zhuangqi Hu 
Published: March 2011

ABSTRACTThe microstructure and the mechanical properties at room and high temperatures of monocrystalline Ni3Al containing 0, 0.52, 1.37, 2.22 and 3.00 at%B have been studied. The results show that the ultimate and yield strengths at 20°C and 800° C of monocrystalline Ni3Al obviously increase with the increase of B content, and reach maxima when B content is 1.37 and 0.52 at% respectively. With further increasing the B content to 2.22 at%, they slowly drop. The tensile ductilities at 20°C and 800°C of monocrystalline Ni3Al when the B content is 0 and 0.52 at% respectively are the best in five kinds of Ni3Al studied, then they continuously decrease with the increase of B content due to the precipitation of boride eutectic. The rupture life and elongation at 850°C and 100 MPa markedly drop as the B content is raised in the monocrystalline Ni3Al, but they are still higher by 1 to 2 orders of magnitude as compared with those of polycrystalline Ni3Al with the same compositions. When B content exceeds 1.37 at%, the eutectic structure of Ni20Al3B6 and Ni3Al is formed, which is enhanced by the B content and is harmful to the strength and the ductility.
On Improving the Fracture Toughness of a Niai-Based Alloy by Mechanical Alloying
Authors: Kostrubanic J. , Koss D.A. , Locci I.E. , Nathal M. 
Published: March 2011

ABSTRACTMechanical alloying (MA) has been used to process the NiAl-based alloy Ni-35Al-2OFe such that a fine-grain (∼2 μm) microstructure is obtained through the addition of 2 v/o Y2O3 particles. When compared to a conventionally processed, coarse-grained (∼;28 μm) Ni-35–20 alloy without the Y2O3 particles, the MA alloy exhibits two to three times higher fracture toughness values, despite a 50% increase in yield strength. Room temperature KQ values as high as 34 √Pa m are observed accompanied by a yield strength in excess of 1100 MPa. Fractography confirms a change in fracture characteristics of the fine-grained MA alloy.
Mechanical Properties of Ordered Fe-Al-X Alloys
Authors: Prakash Ujjwal , Buckley Robert A. , Jones Howard 
Published: March 2011

ABSTRACTFe-Al-X alloys (X = Cr, Mo) in the composition range 50 to 80 at. % Fe, 0 to 20 at. % X were rapidly solidified by chill-block melt-spinning. As-spun and heat treated ribbons were characterised by optical and electron microscopy and X-ray diffraction. Strengthening mechanisms were identified using microhardness measurements. Tensile fracture surfaces of ribbons reveal ductile to cleavage to intergranular fracture transitions with increasing Al-content. An increasing preponderance of cleavage fracture with increasing ternary substitution for Fe was observed.
Tensile and Creep Behavior of Ordered Orthorhombic Ti2A1Nb-Based Alloys
Authors: Rowe R.G. , Konitzer D.G. , Woodfield A.P. , Chesnutt J.C. 
Published: March 2011

ABSTRACTTitanium aluminide alloys with compositions near Ti-25A1-25Nb at.% were prepared by both rapid solidification and ingot techniques. Their tensile and creep properties were studied after heat treatment to produce various microstructures containing ordered orthorhombic (O) [1], ordered beta (βo), and α2 phases. It was found that these alloys had higher specific strength from room temperature to 760°C than conventional α2 alloys. Ductility and tensile strength of O+βo alloys were strongly dependent upon heat treatment, with the highest strength observed as-heat-treated, and the highest ductility after long term aging. The creep resistance of single phase O and two phase O+βo alloys was strongly dependent upon heat treatment.