bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnetic Eiaxaticn and Structural Transfor4Aticn in Metallic Glasses
Authors: O'Handley R.C. 
Published: March 2011

ABSTRACTCurrent understanding of the local atomic structure of amorphous materials is reviewed. Sane results of probing short—range order by selected techniques are cited to illustrate the degree of uniformity that exists on a local scale. Observations of phase separation and phase changes are described with particular emphasis on a temperature driven, reversible transformation of the local structure observed magnetically in several cobalt—base glasses. The manifestations and implications of such transformations within the glassy state are examined. Several examples pointing to quasi—crystalline and to non—crystalline (non—space filling) local structures are given.
Magnetic Domain Structures in Cerium—Doped Fe80B20, Fe80B16Si2C2, and Fe78B13Si9 Glassy Ribbons
Authors: Canright G. S. , Kroeger D. M. 
Published: March 2011

ABSTRACTThe addition of cerium in parts—per—million quantities has been shown to be effective in inhibiting the annealing embrittlement of melt—spun amorphous ribbons [1]. The effects of cerium doping on magnetic domain structures are reported in this paper. Domain structures have been observed using the Bitter colloid technique on the free surfaces of asquenched ribbons, as well as on both surfaces of ribbonswhich have been thinned by electropolishing. In the binary and quaternary alloys, the optimum (in terms of mechanical properties) cerium content gives ribbons which are apparently free of quenched—in stresses, since they lack the commonly observed “maze domains” which are found for both undoped and excessively doped ribbons. In contrast, the ternary alloy, which shows little decrease in annealing embrittlement versus doping, is free of maze domains in the as—quenched condition, with or without doping. The effect on the former two alloys is interpreted in terms of enhanced stress—relief during the quench.
Composition Dependence of Magnetic Shielding Properties for Amorphous Ribbons (FeNi)78Mo4B17Si
Authors: Huang Der-Ray , Dow Wen-Huu , Yao Pei-Chih , Hsu Shu-En 
Published: March 2011

ABSTRACTAmorphous ribbons (FeNi)78Mo4B17Si, made by melt—spinning technique were prepared as magnetic shielding materials. Cylindrical shields (~0.05mm thick) were fabricated by wrapping ribbons on 20cm long pyrex tubes with 45mm diameter. DC and AC (60Hz, 400Hz, 800Hz, 1 kHz) magnetic shielding data were obtained by following the modified ASTM (A698–74) procedure. For DC magnetic fields, Ni—rich shields showed maximum shielding values at lower applied fields (0.1 0e~l 0e), while Fe—rich shields showed maximum shielding values at higher applied fields (1~5 0e). For AC magnetic fields, the magnetic fields, the magnetic shielding effectiveness was also influenced by skin effect at shield' surfaces. By comparing the data to calculations from shielding theory, there is about 8% magnetic shielding effectiveness induced by skin effect at 1 kHz.
Characterization of Inhomogeneities in Amorphous Superconductors
Authors: Alp Esen E. , Malik S.K. , Lepetre Y. , Montano P.A. , Shenoy G.K. 
Published: March 2011

ABSTRACTThe structure and superconducting properties of rapidly quenched Zr—Ni and Zr—V alloys have been studied by XRD,EXAFS spectroscopy,TEM,electron diffraction,ED, electrical resistivity and ac susceptibility measurements. Amorphous Zr66Ni34 ribbons quenched with different cooling rates were also examined by flux pinning measurements. Characteristic differences are observed in the flux pinning mechanisms of microcrystalline and amorphous samples. The temperature dependence of upper critical fields have been measured down to 0.4 K and the results are analyzed in terms of WHH theory.
Magneto—Optical Properties of Amorphous TbFe Alloys
Authors: Mansuripur M. , Ruane M. , Wolniansky P. , Chase S. , Rosenvold R. 
Published: March 2011

ABSTRACTHysteresis loops and anisotropy energy constants are measured in a magneto—optical system that combines Kerr rotation and ellipticity to enhance signal strength. Temperature dependence of the polar Kerr effect is compared with the magnetization of the iron subnetwork in the mean—field approximation and good agreement is obtained. Perpendicular magnetic anisotropy is studied by magneto—optical methods, yielding the first two coefficients of the series expansion of anisotropy energy in terms of the angleof deviation from the easy axis.
Crystallization and Magnetic Studies in Melt-Spun Fe77Nd15−xRxB8 Ribbons
Authors: Rao K.V. , Malmhall R. , Gudimetta Krishna , Hadjipanayis G.C. 
Published: March 2011

ABSTRACTLow field (∿5 Oe)Magneto-Thermo-Gravimetric technique has been used to study the effects of substitution of Nd with Y, Gd, and Dy in melt-spun Fe77Nd15B8 alloys, and also to monitor the changes in the magnetic properties on heat treatment to achieve optimum magnetic hardening in these alloys. From VSM-measurements preliminary studies of the effect of substitution for Nd on the hysteretic loops are presented.
Transport Property Studies on Icosahedral Systems: Rapidly Quenched Al-V, Al-Mn, AND Al-Fe-Mn.
Authors: Rao K. V. , Karpe N. , Malmhall R. , Astrum H. U. , Chen H. S. 
Published: March 2011

ABSTRACTWe report the first Hall, and electrical resistivity study on rapidly quenched icosahedral Al-based alloys. The Hall coefficient is found to be negative and remains so for i(Al-Mn) alloys even for higher Mn concentrations. The magnitude and temperature coefficient of the electrical resistivity behaviour in these alloys is similar to those observed for amorphous metallic alloys. Thus, the conduction process in i(Al-based alloys) is essentially electronic but with a carrier mobility an order of magnitude smaller than that known for crystalline aluminium.
Formation of Icosahedral Al(Mn) by Pulsed Surface Melting
Authors: Follstaedt D. M. , Knapp J. A. 
Published: March 2011

ABSTRACTSurface melting of alternating Al/Mn layers on Al and Fe substrates by pulsed electron beams and laser is found by TEM to produce icosahedral Al(Mn). Interpreting the observed microstructures in terms of the calculated temperature histories places limits on the melting point of the phase (660 0C < T < 9600C), the time needed for its nucleation from the melt at 6600C (t < 50 ns), and the rate of quenching from thg liquid n needed to suppress formation of the competing T phase (-T > - 1 × 10 K/s).
Fractal Coefficients of An Icosahedral Structure of Quasi-Crystals and Amorphous Alloys
Authors: Levy J.C.S. , Mercier D. 
Published: March 2011

ABSTRACTDifferent extended icosahedral structures are obtained from energy minimization and local symmetry Yh. The quasi fractal character of one of these is demonstrated from the quasi algorithm of definition, the gamma density of holes and the measured Hausdorff number ∂. The spectral dimension ∂ is measured and dimensions corresponding to higher derivatives are defined.
The Status and Potential of Rapid Solidification of Magnesium Alloys
Authors: Hehmann F. , Jones H. 
Published: March 2011

ABSTRACTIn spite of giving exceptionally low density and excellent machinability at relatively low cost, magnesium alloys have found only restricted application as engineering materials to date because of limitations in formability, corrosion resistance, strength and creep resistance. Although the very earliest work on record to employ rapid solidification as a means to enhance engineering properties was carried out on magnesium-base alloys, subsequent work employing more modern techniques has not, until very recently, been motivated by the need for alloy development. The present study combines a critical survey of relevant published work with an assessment of the potential of magnesium-base alloys for development by the rapid solidification route.
Plastic Deformation of A Rapidly Solidified Al-Li-Zr Alloy
Authors: Kim N. J. , Das S. K. 
Published: March 2011

ABSTRACTThe deformation behavior of a rapidly solidified Al-3.7%Li-O.5%Zr alloy has been investigated using transmission electron microscopy. Aging of the alloy in a conventional manner produces a homogeneous precipitation of δ' with small amount of heterogeneously distributed composite precipitates. The deformation behavior of the alloy in such aging conditions is dominated by the readily shearable δ', resulting in a pronounced planar slip. A homogeneous distrubution of composite precipitates promoted by double-aging treatment, however, alters the deformation mode to wavy slip by inducing the by-passing of dislocations around the shear resistant composite precipitates.
Effect of Rolling Parameters on the Properties of Al-Fe-V Sheet Rolled on an Experimental Mill
Authors: Brown A. , Raybould D. 
Published: March 2011

ABSTRACTIn recent years, interest in high temperature aluminum alloys has increased. However, nearly all the data available is for simple extrusions. This paper looks at the properties of sheet made from a rapidly solidified Al-10Fe-2.5V-2Si alloy. The sheet is made by direct forging followed by hot rolling, this is readily scalable, so allowing the production of large sheet. The room temperature strength and fracture toughness of the sheet are comparable to those of 2014-T6. The high temperature strength, specific stiffness and corrosion resistance are excellent. Recently, improved thermomechanical processing and new alloys have allowed higher strengths and fracture toughness values to be obtained.
Microstructures and Thermal Properties of Rapidly Solidified Aluminum-Rare Earth Alloys
Authors: Eliezer D. , Savage S. J. , Mahajan Y. R. , Froes F. H. 
Published: March 2011

ABSTRACTRapidly solidified (RS) Al-Er, Al-Nd, and Al-Gd ribbons were prepared by pendant drop melt extraction (PDME). The microstructures were studied in detail by optical and transmission electron microscopy. A wide range of microstructures are observed, including “conventional” RS type zones, a cellular structure surrounded by a degenerate eutectic and coupled (lamellar) eutectic structures. A bimodal precipitate distribution is seen in many areas of the ribbons. A series of isochronal heat treatments was conducted to determine the relative thermal stability of these microstructures, which were evaluated by Knoop microhardness measurements.
Recent Developments in Laser Surface Treatment
Authors: Mordike B.L. , Bergmann H.W. 
Published: March 2011

ABSTRACTSome unrelated examples are given where progress has been made in laser surface treatment in the last few years. These are large scale transformation hardening, reproducible surface melting of cast iron, surface alloying with a reaction with the surrounding atmosphere, fundamental studies of solidification and evaporation cleaning.
Unusual Chemical Composition of Carbides in Rapidly Solidified High Speed Steels
Authors: Tauqir A. , Nowotny H. , Strutt P. R. 
Published: March 2011

ABSTRACTStudies of the elemental composition of carbide phases formed by rapid solidification of a Mo-base high speed steel (M7) have yielded an intriguing finding. Micro-analysis of the extracted carbides (M2C, M23C6 and MC) showea that these were unusually rich in refractory elements with values of Mo in the range 46-53 wt.%, corresponding values for Fe and Cr were low (6-12 wt.% Cr and 1.5-13 wt% Fe). This was in marked contrast with analyses of MC, M6C, M7C3 and M23C6 in the ‘unglazed’ material where Fe and Cr were major constituents. A distinctive feature was M23C6 in the rapidly solidified material which contained large amounts of Mo and W and very little Cr. It is proposed that this phase, initially formed as M6C, underwent solid-state transformation.
Amorphous Cu-Zr and Fe-Ti Compositionally Modulated Films Produced by Sputtering from Elemental Targets
Authors: Chason E. , Kondo H. , Mizoguchi T. , Cammarata R.C. , Spaepen F. , Window B. , Dunlop J.B. , Day R.K. 
Published: March 2011

ABSTRACTAmorphous compositionally modulated films of Cu-Zr and Fe-Ti have been prepared by sequential sputter deposition of the elemental metals. For Cu-Zr, a critical modulation amplitude has been found, below which the samples are entirely amorphous. The effective interdiffusion coefficient during deposition has been estimated, and found to be assisted by the free energy of mixing and the ion bombardment. X-ray studies of the modulation peaks, using grid scans, reveal a sharp mosaic, and asymmetrical peaks in some samples.
Evidence for the Formation of A Metastable Crystalline Phase During Crystallization of Zr-Ni Metallic Glasses of Approximately 57–63.2 at. % Zr
Authors: McKamey C. G. , Easton D. S. , Kroeger D. M. 
Published: March 2011

ABSTRACTThe crystallization of rapidly solidified Zr-Ni metallic glasses has been studied by differential scanning calorimetry (DSC), x-ray diffraction (XRD), and transmission electronmicroscopy (TEM). Evidence has been found for a metastable phase which is the first crystalline phase to form upon heating in compositions of 57 to 63.2 at. % Zr. This phase seems to be more easily formed and is most stable in the region of 58 to 59 at. % Zr. Uponsubsequent heating to higher temperatures, the metastable phase transforms to the equilibrium phases ZrNi and Zr2Ni. The relationship of this new phase to phase separation at the eutectic composition of 63.5 at. % Zr is discussed in support of the conclusions drawn from low temperature specific heat studies reported previously [1,2].
Respirable Fines Produced by Impacts of Simulated Alternative High-Level Waste Materials
Authors: Jardine Leslie J. , Reedy Gerald T. , Mecham William J. 
Published: March 2011

ABSTRACTStandardized comparative drop weight impact tests were conducted on solid alternative waste forms under consideration for immobilizing Savannah River Laboratory (SRL) defense wastes. The fragment size distributions were measured in the size ranges of ֮5 to 8000 μm. All waste form fragment size distributions could be described accurately by lognormal plots. Respirable sizes (≤10 μm) were measured. Borosilicate glass and SYNROC specimens yielded the same mass fractions of respirable sizes; FUETAP concrete, high silica and alkoxide glass specimens yielded ֮2–3 times more mass fractions of particles of respirable sizes, whereas tailored (Spinel) ceramic specimens yielded the smallest mass fractions of respirable sizes, ֮2–1/2 times less.
Stability of I and SR Radiophases in Cement Matrices
Authors: Barnes M.W. , Scheetz B.E. , Wakeley L.D. , Atkinson S.D. , Roy D.M. 
Published: March 2011

ABSTRACTThe following study is a portion of a comprehensive research program that is examining the stability of a variety of nuclear waste forms. In addition to the bulk waste forms, important individual radiophases are being studied to obtain a more complete understanding of the behavior of the components of complex multiphase radwaste systems. The stability of the strontium radiophase in supercalcine and an iodine-radiophase will be discussed.The strontium radiophase in this study was Sr-powellite and the iodine radiophase was I-sodalite. Each radiophase was incorporated into bulk compositionally adjusted portland and aluminate cements. Two processing variables were studied: curing at 60°C and warm pressing at 150°C and 345 MPa.Sr-powellite in portland cement leaches incongruently; a combination of dissolution and diffusion-controlled exchange of Ca for Sr is demonstrated. In the warm-pressed aluminate cement these reactions are masked by reactions with the curing cement. I-sodalite leaching data indicate dissolution, dominant at long times, combined with diffusion, dominant at short times.
Nuclide Migration Field Experiments in Tuff, G Tunnel, Nevada Test Site
Authors: Erdal B. R. , Rundberg R. S. , Daniels W. R. , Wolfsberg K. , Friedman A. M. , Fried S. , Hines J. J. 
Published: March 2011

ABSTRACTA project to begin to address the phenomena of flow and element migration in fractured porous rock has recently been started by the Los Alamos National Laboratory, Sandia National Laboratories, and Argonne National Laboratory. The work has three objectives: 1) to develop the experimental, instrumental, and safety techniques necessary to conduct controlled, small-scale, radionuclide migration, field experiments; 2) to use these techniques to define radionuclide migration through rock by performing generic, at-depth experiments under closely controlled conditions in a single fracture in porous rock; and 3) to determine whether available lithologic, geochemical, and hydraulic properties together with existing or developed transport models are sufficient and appropriate to describe real field conditions (i.e., to scale from small-scale laboratory studies to bench-size studies to field studies). The detailed scope of this project and its current status are described.
Transient Hydraulic Tests in Granite: Fissured Porous Medium Analysis and Results
Authors: Black John H. , Barker John A. 
Published: March 2011

ABSTRACTSlug and pulse tests have been used extensively to measure the hydraulic conductivity and specific storage of granitic rocks. After several hundred tests using an I.G.S. design of straddle packer test equipment, it became clear that the conventional methods of test analysis were inadequate. The straddle packer equipment developed by IGS allows the time scale of a test to be altered without repositioning the packers so that a range of tests can be carried out on the same test interval. The new analysis procedure presented here uses a model of fissured rock which incorporates water movement in both the fissures and the rock matrix. A new variable is introduced which includes the parameters matrix hydraulic conductivity, matrix specific storage fissure specific storage and fissure hydraulic conductivity together with the controllable variables, effective casing radius and packer interval length. Examples of analysis using multiple tests in the same interval are presented together with the apparent relationship between measured hydraulic conductivity and specific storage. It would appear that a small number of fissures endow the rock mass with the bulk of its hydraulic conductivity and that many of the higher hydraulic conductivity tests are probably associated with localised “pipe flow”.
Uranium-Lead Radiometric Age Determinations of Naturally Occurring U(VI) Minerals: Application to Radwaste Storage
Authors: Brookins Douglas G. 
Published: March 2011

ABSTRACTU(VI) bearing species are commonly formed under oxidizing laboratory rock-water-HLW experimental conditions. The experimental stability of artificially produced Na-Cs-Rb weeksite (alkali uranyl hydrosilicate), and other U(VI) species, is uncertain. Naturally occurring U(VI) bearing minerals (uranophane and tyuyamutrite) from the Grants mineral belt, New Mexico, have been studied for their U-Pb systematics as natural analogs to these experimentally produced phases. Samples from highly oxidized rocks and from chemically reducing environments have been studied. The samples from oxidized rocks are mixed with hematite-barite-gypsum-calcite gangue and are close to, but not in contact with, pyritiferous-organic carbon-uraniferous (U(NIV))-chloritic are. The reduced rock uranophane yields nearly concordant238U - 206Pb and 235U - 207Pb ages of 8.32 and 8.33 MYBP (millions of years before the present); the oxidized rock uranophane and tyuyam .nite yield more discordant ages (n=8) between 7.4 and 2.7 MYBP. These data argue for long range stability of U(VI)-rich phases in the geologic environment.
Radiogeological Assessment of Candidate Sites For Nuclear Waste Repositories, Exemplified by Studies of The Stripa Pluton, Sweden
Authors: Wollenberg H. A. , Flexser S. , Andersson L. 
Published: March 2011

ABSTRACTInvestigation of candidate sites for nuclear waste isolation will require an assessment of their radiogeologic settings. Studies at the Stripa research facility in granitic rock of central Sweden incorporated the distribution and abundance of naturally occurring radioelements in rocks encompassing the underground experiments and in the accompanying fracture-controlled groundwater system. These studies showed that besides defining the natural radioactivity baseline upon which the effects of radioactive waste will be superimposed, radioelement distributions can be used to determine the apparent age of the groundwater and its flow paths. In crystalline rocks, where the groundwater systems are confined to the joints and fractures, the uranium daughter element, radon-222 in the water serves as a natural tracer to locate fractures along which significant flow is occurring and to measure the flow rates. The heat production from radioactive decay of uranium-238, thorium-232 and potassium-40 in the rock, combined with measurements of regional and local geothermal heat flow, permit calculation of the apparent size of the rock mass that will encompass the repository. This method is especially useful in terranes such as at Stripa where the contacts between plutons and older rocks are concealed.
Diffusion Measurements in Compacted Bentonite
Authors: Torstenfelt B. , Andersson K. , Kipatsi H. , Allard B. , Olofsson U. 
Published: March 2011

ABSTRACTThe diffusion of Cs, Sr, Am and Tc in compacted bentonite clay has been studied, using a diffusion cell where diffusion takes place axially from the center of a cylinder of the clay. The effect of addition of potential radionuclide getters to the clay (apatite for Am, pyrite, olivine, and Fe(s) for Tc) as well as using complexed (acetate) or colloidal Am has been studied.The diffusivities obtained for Cs and Sr were very high − 9.0×10−13 m2/s and 2.6×10−12 m2/s, considering that if the effect of sorption on the clay 9is 2 substracted the diffusivities would be 1.8×10−9 m2/s and 3.1×10−8 m2 /s. These diffusivities are, however, maximum values as the concentration profiles do not follow the theoretical form for these nuclides. A small amount of the ions seems to migrate very fast, while the rest moves slower.For Tc, that may be expected I b2 anionic and thus poorly sorbed, a diffusivity of 5.3×10−11 m2/s was obtained. Addition of Fe(s) decreases the diffusivity by one order of magnitude while olivine and pyrite have no measurable influence during the present contact times (2-3 months). Americium is practically immobile.
Corrosion of Construction Materials in Clay Environments
Authors: Dresselaers Jozef , Casteels Florent , Tas Hugo 
Published: March 2011

ABSTRACTThe corrosion rate and mechanism of construction materials of galleries and casings for boreholes (possibly to be used as consumable overpack of HLW canisters) have been evaluated after a first campaign of corrosion experiments in direct contact with clay, in a humid clay atmosphere and in a gas corrosion chamber. The envisaged construction material is ductile iron (grade 60) and has been tested with and without metallic and organic coatings. The corrosion mechanism is governed by the formation of a rust scale composed of Fe3O4 and C. Preferential attack underneath the surface reaction layer is associated with the progress of a reaction front at the interface between the graphic nodules or flakes and the ferritic or pearlitic structure.Post-corrosion analyses of old gray iron coal mine shafts exposed for 60 and 90 years in well defined conditions are included to validate the use of the results of the short-time tests for very long exposure times.