bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasticity, Dislocation Structures and Antiphase Boundary Energies in Fe3Al Single Crystals with Chromium
Authors: Král Filip , Schwander Peter , Kostorz Gernot 
Published: April 2011

ABSTRACTThe influence of Cr additions on the positive temperature dependence of the critical resolved shear stress of Fe3Al is investigated. Single crystals of binary Fe-28 at.% Al and ternary Fe-28 at.% Al-6 at.% Cr with different orientations are deformed in uniaxial compression between room temperature and 1273 K. The dislocation arrangement and the dissociation of superdislocations are studied by transmission electron microscopy using the weak-beam technique. The operative slip systems are discussed on the basis of the direct measurements of the antiphase boundary energies and of the activation volume.
In Situ TEM Observations of Cross-Slip Mechanisms in NiAl with a Soft Orientation
Authors: Vailhe C. , Douin J. , Caillard D. 
Published: April 2011

ABSTRACTIn situ experiments have been conducted in NiAl single crystals in the soft orientation, at room temperature, in order to investigate the glide process of [100] dislocations. The results show that dislocations have a kinked shape in agreement with what is expected from anisotropie elasticity. Intensive cross-slip is observed, leading to slip in non-crystallographic planes and dipole formation. The ductility of the alloy is then discussed.
Powder Processing of NiAl for Elevated Temperature Strength
Authors: Daniel Whittenberger J. , Grahle Peter , Arzt Eduard , Behr Robert , Zöltzer Klaus , Hebsur Mohan 
Published: April 2011

ABSTRACTIn an effort to superimpose two different elevated temperature strengthening mechanisms in NiAl, one lot of an oxide dispersion strengthened (ODS) NiAl powder has been milled in liquid nitrogen (cryomilled) to introduce A1N particles at the grain boundaries, and a second lot of ODS powder was simply roasted in gaseous nitrogen as an alternative means to produce AIN reinforced grain boundaries. Powder from both of these lots as well as the starting material have been consolidated by hot extrusion and tested at 1300 K. Both nitrogen roasting and cryomilling produced AIN within the ODS NiAl matrix which strengthened the alloy; however, based on the AIN content, cryomilling is more effective.
Strain Aging behavior In NiAI Microalloyed with Interstitial and Substitutional Solutes
Authors: Weaver M. L. , Noebe R. D. , Kaufman M. J. 
Published: April 2011

ABSTRACTDynamic strain aging has been investigated in polycrystalline NiAl alloys containing combined additions of interstitial and substitutional impurities. The results indicate that strain aging can be enhanced in polycrystalline alloys containing concentrations of silicon or iron in excess of 0.15 at.% in addition to conventional levels of carbon. This co-doping leads to very dramatic strain aging events, comparable to those typically observed in single crystals. This effect will be discussed with respect to conventional theories of strain aging.
High-Temperature Mechanical Behavior of B2 Type IrAl Doped With Ni
Authors: Chiba A. , Ono T. , Li X. G. , Takahashi S. 
Published: April 2011

ABSTRACTConstant-velocity and constant-load compression tests have been conducted to examine the mechanical behavior of polycrystalline IrAl and Ir1-xNixAl at ambient and elevated temperatures. Although IrAl exhibits brittle fracture before or immediately after yielding below 1073K, steady-state deformation takes place at temperatures higher than 1273K. Ductility of Ir1-xNixAl is improved with increasing x. On the contrary, strength decreases with increasing x. IrAl exhibits the 0.2% flow stress of 1200MPa at 1073K and 350MPa at 1473K, about an order of magnitude higher than NiAl. Secondary creep of IrAl and Ir0.2Ni0.8Al(i.e., modified NiAl) exhibits class II and class I behavior respectively. Creep strength of binary IrAl and modified NiAl with Ir is about a magnitude of 4 higher than that of single-phase and multi-phase NiAl at a given applied stress.
Microstructure and Phase Separation of Pekk, Pekk and their Blends
Authors: Wang Wu. , Schultz Jerold M. , Hsiao Benjamin S. 
Published: April 2011

ABSTRACTMicrostructures of PEEK|PEKK blends at both structural and lamellar levels were studied using simultaneously time-resolved small-angle and wide-angle x-ray scattering (SAXS and WAXS) with synchrotron radiations. Lamellar dimensions and unit cell parameters were determined, and phase separation within the blends were observed. A suitable two-phase growth model is proposed. It is concluded that when crystallized from the melt, PEEK and PEKK lamellae formed in separate lamellar bundles within a common spherulite.
Mechanical Alloying of Pet and Pet/Vectra Blends
Authors: Balik C. M. , Bai C , Koch C.C , Spontak R.J , Saw C. K. 
Published: April 2011

ABSTRACTMechanical alloying represents a potential method for producing finely dispersed alloys of normally incompatible polymers. In this paper, PET and blends of PET with a Vectra thermotropic copolyester have been processed via high energy ball milling at room temperature (ambimilled) and at liquid nitrogen temperatures (cryomilled). Milled powders and compacted disks have been characterized using molecular weight, density and hardness measurements, aswell as DSC, WAXS, TEM and FTIR.
Refractory Ceramics From an Iron Age Bronze Melting Workshop at Khirbet Edh-Dharih, Jordan
Authors: Klein S. , Hauptmann A. , Vandiver P.B. 
Published: April 2011

ABSTRACTAn excavation at Khirbet edh-Dharih implemented by the Institut Français D'Archaéologie du Proche-Orient brought forth a few archaeometallurgical remains such as lumps of bronze, slags, and refractory ceramic fragments. Khirbet edh-Dharih is located in Jordan, near the Feinan area at Wadi Arabah. The Feinan area is well known as a major supplier of copper in the Near East's history from the Chalcolithic to the Roman period. The remains from Khirbet edh-Dharih were dated from the Iron Age II, and they are pointing to a workshop for further treatment of copper from Feinan. Khirbet edh-Dharih is the first bronze melting site excavated in the Feinan copper district.
Electron Spin Resonance Characterization and Provenance of Marbles: The Case of the “Cipollino Verde”
Authors: Armiento Giovanna , Attanasio Donato , Platania Rosario 
Published: April 2011

ABSTRACTThe possibility of using Electron Spin Resonance Spectroscopy (ESR) for identifying the quarries of provenance of classical marble artifacts has been reexamined and applied to the sample case of the so-called “Cipollino Verde” marble. The method gives qualitative and quantitative information on Mn2+ and other paramagnetic impurities present in marble and the assignment is made on a statistical basis, using a properly defined database. Like other, well established, techniques, ESR seldom yields an unequivocal answer to the provenance problem. However, it provides valuable information and, coupled with other methods, reduces the existing uncertainties often leading to the final assignment.
Macro- and Micro- Non Destructive Tests for Environmental Impact Assessment on Architectural Surfaces
Authors: Moropoulou A. , Koui M. , Tsiourva Th. , Kourteli Ch. , Papasotiriou D. 
Published: April 2011

ABSTRACTSeveral non destructive techniques are recently applied to assess and evaluate weathering damages. In the present work several macro- and micro- non destructive tests, have been employed, in the Fortress of the Medieval City of Rhodes, for the examination of the weathering: Digital Image Processing for the mapping of the decay patterns, Fibre Optics Microscopy for the examination of the morphological characteristics of the surface, and Infra Red Thermography for the assessment of the humidity distribution within the masonries and the degradation of the stone texture. The results of the above methods are supported by porosity and humidity measurements regarding the evaluation of the microstructural characteristics of the stone and the water percolation within the masonry. It is proved that these three methods can be combined into a reliable assessment tool concerning environmental impact on architectural surfaces and particularly in the form of a thorough characterization of the materials degradation.
Scanning Auger Microscopy and X Ray Photoemission Spectroscopy Studies of Metallic Archaeomaterials
Authors: Paparazzo E. , Moretto L. 
Published: April 2011

ABSTRACTWe report on the surface microchemistry of a Roman iron object and of a Roman lead pipe ‘fistula’. The original patina of the iron sample consists mainly of oxidic phases whose lateral distribution is imaged with a submicron spatial resolution. Metallic iron in the bare surface is covered with a Fe(lll)-Fe(ll) oxidic layer which is several times thicker than in a modern ferritic steel. We find that the presence of a flux minimizes lead oxidation in the joint of the fistula as well as in comparison, ‘modern’ lead soldered samples. In one of these comparison samples the lateral distribution of the chemical species present is imaged with a spatial resolution of about 1000 Å.
Provenance Determination from ICP-MS Elemental and Isotopic Compositions of El Paso Area Ceramics
Authors: Pingitore Nicholas E. , Leach Jeff D. , Villalobos Joshua , Peterson John A. , Hill David 
Published: April 2011

ABSTRACTTo evaluate the performance of inductively coupled plasma mass spectrometry (ICP-MS) in determining ceramic provenance, we analyzed 60 elements in 30 ceramic artifacts from six a priori groups from west Texas-southwestern New Mexico. Discriminant function analysis of the ICP-MS elemental data classified all members of the six a priori groups without error. In repeated analyses using 80% of the data as a training set, overall 75% of the withheld specimens were properly classified. Lead isotope ratios, also measured on the ICP-MS, provided an independent partial discrimination between the groups. The results of this study demonstrate that ICP-MS provides multi-element and lead isotopie characterization of archaeological ceramics suitable for provenance determination. ICP-MS is a rapid, in-house, and relatively inexpensive technology and thus is a reasonable alternative to neutron activation analysis (NAA) for compositional studies of archaeological ceramics.
The Archaeometallurgical Implications of New Findings of Traditional Crafts of Making High Tin ‘Delta’ Bronze Mirrors and ‘Beta’ Bronze Vessels in Kerala State of South India
Authors: Srinivasan Sharada 
Published: April 2011

ABSTRACTNew metallurgical and ethnographic observations of the traditional manufacture of specular high-tin bronze mirrors in Kerala state of southern India are discussed, which is an exceptional example of a surviving craft practice of metal mirror-making in the world. The manufacturing process has been reconstructed from analytical investigations made by Srinivasan following a visit late in 1991 to a mirror making workshop and from her technical studies of equipment acquired by Glover in March 1992 from another group of mirror makers from Pathanamthita at an exhibition held at Crafts Museum, Delhi. Finished and unfinished mirror from two workshops were of a binary, copper-tin alloy of 33% tin which is close to the composition of pure delta phase, so that these mirrors are referred to here as ‘delta’ bronzes. For the first time, metallurgical and field observations were made by Srinivasan in 1991 of the manufacture of high-tin ‘beta’ bonze vessels from Palghat district, Kerala, i‥e of wrought and quenched 23% tin bronze. This has provided the first metallurgical record for a surviving craft of high-tin bronze bowl making which can be directly related to archaeological finds of high-tin bronze vessels from the Indian subcontinent and Southeast Asia. New analytical investigations are presented of high-tin beta bronzes from the Indian subcontinent which are some of the earliest reported worldwide. These coupled with the archaeometallurgical evidence suggests that these high-tin bronze techniques are part of a long, continuing, and probably indigenous tradition of the use of high-tin bronzes in the Indian subcontinent with finds reported even from Indus Valley sites. While the source of tin has been problematic, new evidence on bronze smelting slags and literary evidence suggests there may have been some sources of tin in South India.
Quantitative High Resolution Transmission Electron Microscopy - The Role of Space Charge in Blurring Images
Authors: Schwartz A. M. , Gibson J. M. , Zheng T. 
Published: April 2011

ABSTRACTWe investigate space-charge by analytic methods and Monte Carlo simulations as a possible source of blur in high-resolution TEM images. In doing so we believe to have identified a novel type of space charge effect, namely quantum space charge(QSC) effect. We predict the blur for typical HRTEM images and for electron holograms. Inclusion of this hitherto unrecognized effect in image simulations (and experimental design for HRTEM and related techniques, such as holography) should permit further progress in the critical field of quantitative HRTEM image matching as a means for atomic structure determination.
Quantitative High Resolution Electron Microscopy of Grain Boundaries
Authors: Campbell Geoffrey H. , King Wayne E. , Cohen Dov , Carter Barry 
Published: April 2011

ABSTRACTThe Σ11 (113)/[110] symmetric tilt grain boundary has been characterized by high resolution transmission electron microscopy. The method by which the images are prepared for analysis is described. The statistics of the image data have been found to follow a normal distribution. The electron-optical imaging parameters used to acquire the image have been determined by non-linear least-square image simulation optimization within the perfect crystal region of the micrograph. A similar image simulation optimization procedure is used to determine the atom positions which provide the best match between the experimental image and the image simulation.
Evolution of Morphology During Etching of Si
Authors: Williams Ellen D. , Fu Elain S. , Li Bin 
Published: April 2011

ABSTRACTThe step morphology of clean Si surfaces has been studied under conditions of thermal etching in the temperature range 950 – 1250°C. Kinetic-bunching of steps is caused by direct current in the step-down direction around 950°C. By comparing the rate of thermal decay of these structures with and without direct current, the electromigration force causing this step bunching is estimated to be due to an effective charge of less than or approximately 0.01 electron units. Around 1150°C, step-bunching is caused by direct current in the step-up direction. By analysis of the patterns of step structure, the effective charge of the driving force is found to be approximately -0.1 electron units. Oxygen-induced etching of Si(001) and Si(111) has been studied in the temperature range of 700 – 900 °C, and at a pressure of 5 × 10−7 torr, conditions under which the surface is etched by the desorption of SiO. On Si(001), the original narrow distribution of double-layer height steps is preserved during the oxygen-etching process. On Si(111), the original narrow distribution of mixed single- and triple-layer height steps changes dramatically during oxygen-etching, leaving wide terraces of flat (111) surface separated by regions of high step density. At low etching temperatures (700°C), the steps remain straight within the step bunches and retain their distinct character as single- and triple-height steps. However, following higher temperature etching, the steps begin to merge into facets in the vicinity of defect structures. Following etching at the highest temperatures studied (815 and 830°C), the pinning action of the defect structures becomes apparent, and the pinned step-bunches become identifiable as (113) facets.
STM Study of Reconstruction on Si(III)
Authors: Umekawa M. , Ohara S. , Tatsukawa S. , Kuriyama H. , Matsumoto S. 
Published: April 2011

ABSTRACTThe formation of the boron-induced reconstruction on Si(111) 7×7 surface has been studied with scanning tunneling microscope. By evaporating elemental B on Si elevated at high temperatures, reconstructed structures develop from the step edge to the adjacent lower terrace. They emerge at temperatures between 800°C and 900°C. It indicates that phase transition from 7×7 to 1×1 surface structure is necessary for forming the √3-B reconstructed structures. The phase boundary between 7×7 and regions is a straight line with termination of the faulted halves of 7×7 unit cell. It is also found that strip or triangle regions are formed, depending on the direction of the step propagation.
Ferroelectric Domain Boundaries Induced by Interface Mismatch Dislocations in BaTiO3/LaAlO3
Authors: Wang Z. L. , Dai Z. R. 
Published: April 2011

ABSTRACTInterface microstractures of BaTiO3/LaAlO3 grown by metal-organic chemical vapor deposition (MOCVD) are studied using high-resolution transmission electron microscopy (HRTEM). Interface dislocations in BaTiO3/LaAlO3 have been shown to be directly linked with the 90° domain boundaries in BaTiO3. This association is a result of strain relief due to a phase transformation on cooling from the growth temperature. The {100} surfaces of BaTiO3 are terminated with the Ba-O layer.
Characterization of Heterointerfaces in Thin-Film Transistors by Cross-Sectional Transmission Electron Microscopy
Authors: Kuroda K. , Tsuji S. , Hayashi Y. , Saka H. 
Published: April 2011

ABSTRACTHydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs) are now widely used as elements for active matrix liquid crystal displays. The nanometer-scale multilayered structure of a-Si:H TFTs has been characterized by cross-sectional transmission electron microscopy (TEM). The discrete layer construction of a faulty TFTs and the generation of defects during manufacturing processes have been investigated. A combination of focused ion beam (FIB) etching and cross-sectional TEM leads to a successful failure analysis. A contamination layer with a thickness of 10–30 nm and microvoids inside multilayers are identified in faulty TFTs. An a-Si layer on silicon nitride (SiNx) is crystallized during TEM observation. Electron energy loss spectroscopy analysis indicates that the diffusion of nitrogen into a-Si layer causes the crystallization.
Analysis of Interface Structures by Quantitative High-Resolution Transmission Electron Microscopy
Authors: Kienzle O. , Exner M. , Ernst F. 
Published: April 2011

ABSTRACTQuantitative evaluation rather than visual inspection of HRTEM images provides objective, reproducible, and very accurate information on the atomistic structure of internal interfaces. This paper explains the method we have developed to analyze the structure of grain boundaries. To demonstrate the power of our approach we present an analysis of the Σ3 (111) grain boundary in SrTiO3. We have determined the coordinates of the atom columns at this interface with a precision of 0.015 nm. Thus, our experimental results provide a sensitive test for physical theories and model structures obtained by computer simulation. First results of computer modeling are presented in this paper. The calculated structure of minimum energy has the same characteristic features as the structure determined by experiment.
Hydrogen Molecule in Silicon Crystal
Authors: Nakamura K. G. , Ishioka K. , Kitajima M. , Murakami K. 
Published: April 2011

ABSTRACTAb initio Hartree-Fock calculations have been performed on a hydrogen molecule in silicon crystal using a cluster model of Si10H16. The hydrogen molecule is stable at a tetrahedral site of silicon. A calculated vibrational frequency of the hydrogen molecule is in reasonable agreement with the experimentally determined frequency of H2 in the silicon crystal.
Boron Gettering by Fluorine in Ion Implanted Silicon
Authors: Krasnobaev L.Ya. , Cuomo J. J. , Vyletalina O. I. 
Published: April 2011

ABSTRACTSi was implanted with fluorine and boron ions. Boron gettering by fluorine was studied. By varying the implantation energy of F+ ions, three types of samples were made in which Rp(F)<Rp(B), Rp(F)∼Rp(B) and Rp(F)>Rp(B). There are three special regions in which the redistribution of Boron atoms during annealing differ. The first one is the near surface region in which the Boron concentration exceeds the value of Boron solid solubility at the annealing temperature. In this region, B atoms are intensively redistributed and have two peaks of concentration. The positions of these peaks coincide with the position of the peaks on the fluorine concentration profile. In the second specific region, the boron concentration is less than the value of solid solubility in Si and higher than the value of the intrinsic carrier concentration in Si at the annealing temperature. In this region, the B concentration was identical in all samples, and it exponentially decreased to the value of 5×108 cm−3. The slope of the boron concentration in the third region dictates the depth of p-n junction. A possible mechanism of boron gettering by fluorine is discussed.
Interstitial Silicon Sink Efficiency of Dislocations Studied by Gold Diffusion in FZ and Cz Samples
Authors: Mariani G. , Pichaud B. , Yakimov E. 
Published: April 2011

ABSTRACTThe substitutional gold concentration introduced by a diffusion step between 850 and 1000°C was measured by Deep Level Transient Spectroscopy (DLTS) both in FZ and Cz silicon containing different dislocation densities introduced by cantilever bending. The comparison, in the same sample, of dislocated and undislocated regions allows first the self interstitial (Sii) effective diffusivity and then the efficiency of dislocations as sinks for self-interstitials γto be measured. In FZ silicon, γ is quite independent of temperature whereas in Cz Si a remarkable temperature dependence was observed, with an effective activation energy of leV, which can be attributed to the release of dislocations by a thermally stimulated climbing mechanism from obstacles (oxygen segregation or precipitation). Increasing the gold diffusion annealing times for a given temperature (850°C) underlines once more the role of the oxygen precipitation in the samples.
Statistical Analysis of Boundaries in NiO Films Grown on Ni Single Crystals
Authors: Zhilyaev A. P. , Li Hualong , Czerwinski F. , Szpunar J.A. 
Published: April 2011

ABSTRACTAn attempt was made to apply the statistical analysis of NiO grain boundaries to explain the dependence of NiO growth kinetics on the crystallographic orientation of Ni substrate. Study was conducted for two crystals faces of Ni, (100) and (111), which exhibits a difference in oxidation rate constants at 1073 K, over one order of magnitude. The orientation distribution functions (ODF), calculated from X-ray measurements for NiO grown on both Ni faces, were analyzed numerically to assess the grain boundary character. The grain boundary misorientation distribution (GBMD) and grain boundary character distribution (GBCD), used to describe oxide structure, were derived using three different assumptions regarding the spatial correlation in orientation of neighbouring grains. Grain boundary network was created to analyze the high temperature diffusion properties through the oxide using diffusion constants available in the literature under assumption of various contribution of bulk and grain boundary diffusion paths to overall transport of ionic species. The growth parameters obtained were finally verified by comparison with experimentally measured oxidation kinetics.