bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron-Beam-Induced Damage in GaAs/AlGaAs Heterostructures
Authors: Tanaka N. , Kawanishi H. , Ishikawa T. 
Published: March 2011

ABSTRACTWe have investigated the effects of electron beam (EB) irradiation on the optical and electrical properties of GaAs/AlGaAs heterostructures in the energy range between 5 and 25 keV. By using 10 keV-EB irradiation, the photoluminescence from quantum wells is shown to be degraded at doses higher than 1×1019 electrons/cm2, further, the two-dimensional-electron-gas mobility is degraded at doses more than 5xl020 electrons/cm2. EB irradiation of 5 and 25 keV, on the other hand, produces no degradation of both properties even at these dose levels. Such an energy dependence of EB-induced damage can be interpreted in terms of the EB energy dependence of the electron penetration and energy-loss-rate. Electrons with an incident energy of 5 keV do not penetrate sufficiently deep into the active region, and 25 keV electrons have an energy-loss-rate that is too low to cause damage.
Metastable Phases Obtained by Laser Glazing in Fe-B And Fe-C Based Alloys
Authors: Antonione Carlo , Battezzati Livio , Riontino Giuseppe , Turco Cosima 
Published: March 2011

ABSTRACTAmorphous phases are observed in laser glazed Fe82 Bl2C6, Fe 82 C18 alloys by Transmission Electron Microscopy. Differential Scanning Calorimetry is used to monitor the amorphous to crystalline transformation. Metastable crystalline structures are also found, such as e-phase in Fe82 C18 and Fe 70Mo10 C20 alloys and, respectively, very fine bainite and retained austenite.
Dynamic Processing Characteristics for Melt Spinning
Authors: Adler R.P.I. , Hsu S.C. 
Published: March 2011

ABSTRACTAlthough during melt spinning the ongoing interactive thermal and mass transfer processes are affected by both materials properties and process variables, a simplified resolution for this complex system can be obtained by first identifying and characterizing those substrate and melt material combinations that provide useful, steady state production performance. A previously described standardized falling droplet/inclined plane test procedure that simulates the dynamic wetting and solidification behavior during melt spinning is being used to generate a range of phenomenological information for combination of melt (droplet) and substrate (plane). Real differences in dynamic wetting/solidification patterns are being correlated with melt spinning performance. Phenomenological and process characteristics from some melt spinning experiments for representative material combinations have been analyzed to verify the validity of these projected correlations as well as to provide complementary information about the interrelation of melt puddle/substrate dynamics with product dimensions and quality.
A Kinetic and Thermal Study of the Superalloy Melt Spinning Process
Authors: Huang S. C. , Laforce R. P. 
Published: March 2011

ABSTRACTThe correlation between ribbon thickness and the length of the melt puddle residing on the surface of a melt-spinning wheel was established for a Ni-base superalloy. Since the melt puddle length defines the solidification time in which a ribbon with a certain thickness is formed, the above correlation allowed a direct derivation of the propagation velocity of the solid-liquid interface. The solidification rate V (mm/s) so obttined as a function of ribbon thickness S (mm) is V = 3.54S−1. Further, the above solidification correlation was analyzed using heat transfer considerations to yield information about the ribbon-wheel interfacial thermal conductance, the solid-liquid interfacial temperature, and the local cooling rate through the ribbon thickness. These thermal results are compared to those deduced from the secondary dendrite arm spacing measurements. Finally, there is a discussion on the ribbon microstructure based on our rapid solidification kinetic result.
Structure and Consolidation Properties of Some Melt Extracted Steels
Authors: Wood J.V. , Gagg C. 
Published: March 2011

ABSTRACTA range of Fe-Mn and Fe-Ni steels have been processed by melt extraction to give fibres and particulate. The consolidation and sintering performance of these alloys are presented. Densities of up to 95% can be achieved with hardnesses in the range 400–500 Hv while possessing grain sizes less than 20μm. Salient features of the sintered structures are described and it is concluded that sintering of pre-annealed short fibres compares favourably with a more conventional approach using powders.
Hot Isostatic Consolidation of P/M Superalloys
Authors: Kissinger R.D. , Nair S.V. , Tien J.K. 
Published: March 2011

ABSTRACTThe kinetics of powder consolidation, or densification, and the powder morphological changes ocurring during hot isostatic pressing (HIP) are studied as a function of particle size distribution and hold time at HIP temperature for the nickel base superalloy RENE-95. In order to understand the extent of individual powder particle deformation during consolidation and its effect on subsequent prior particle boundaries (PPB), particle size distribution was studied as a variable. Particle size distributions studied include monosized (75–90 um), bimodal ( 75–90 um and 33–35 um) and commercial (<104 um) size distributions. The experimental results of HIP densification kinetics are compared with a newly developed analytical deformation mechanism model for HIP consolidaiton which takes into account the effect of a distribution of particle sizes on the kinetics of densification.
Dispersion Strengthening of Metallic Glasses
Authors: Donovan P.E. 
Published: March 2011

ABSTRACTIt is proposed that the effects of crystalline inclusions on the mechanical properties of metallic glasses are due to the presence of compressive stress-fields arising from the difference in thermal expansion coefficients of the crystals and the glass. Because of the dilatational micro-mechanism of plastic flow in metallic glasses these compressive stresses raise the tensile fracture stress but reduce the hardness. The temperature dependence of the hardness changes in partially crystallised Fe40Ni40P14B6 is consistent with this model.
The Effect of Phosphorous on the Corrosion Resistance of Glassy Copper Zirconium Alloys
Authors: Burleigh T.D. , Latanision R.M. 
Published: March 2011

ABSTRACTPhosphorous has been shown to have a beneficial effect on reducing the corrosion rate of various metal alloys. This research was undertaken to determine by what mechanism the phosphorous is able to improve the corrosion resistance of metals. The amorphous copper-zirconium system was chosen for experimentation because the amorphous structure eliminates the complications due to crystalline defects. The zirconium forms zirconia (ZrO2), which is normally a protective surface oxide. Copper-zirconium alloys with and without phosphorous were melt-spun, and were tested in various electrolytes. In comparing Cu-42Zr-2P with Cu-4OZr, the results show that the corrosion rate of Cu-42Zr-2P is lower in 1N sulfuric acid, and significantly lower in 3.5 w/o NaCl, and in 1N HCl. ESCA analysis shows that phosphorous is present in the zirconia film, and has a valence of +5. Photocurrent experiments suggest that phosphorous alters the semiconductor properties of the zirconia film.
Relaxation and Mechanical Properties Of Fe40Ni40B20
Authors: Hunger G. , Fritsch H. U. , Bergmann H. W. 
Published: March 2011

ABSTRACTChanges in physical and mechanical properties were correlated with relaxation phenomena. A quantitative description of the process is possible. Due to the anisotropy, relaxation in a particular direction does not give the same results as volume properties.
Laser Anneal and the Amorphous-Crystalline Transition in the Cu60-Zr40 Alloy System
Authors: Otooni Monde A. 
Published: March 2011

ABSTRACTRecently, significant advances have been made in establishing a theoretical basis for explaining the many structural-sensitive physical properties of amorphous materials. Viewed from both the theoretical and experimental realms, reversible annealing dependency and the structural relaxation mechanism of the amorphous solids are conceptually deducible from the concept of localized structural fluctuations. In the case of annealing, however, the limiting temperature below which no permanent atomiclevel rearrangements occur is not known and may well be dependent on several intrinsic properties of the amorphous state. In an effort to establish this limiting temperature, amorphous Cu60-Zr 40 samples have been annealed using a 1kv pulsed laser. Samples annealed during 1200, 800, 600 400, and 200 μ sec. have been analyzed by using Differential Scanning Calorimetry (DSC), High Resolution Electron Microscopy (HREM), and microanalysis. Analysis of the DSC indicates variations in both height and the shape of the exotherms from the samples annealed above 600 μ sec. duration. The results from HREM of these samples indicate the onset of amorphous-crystalline transition evidenced during 200 μ sec. annealing.
Induced Nucleation and Growth Mechanisms in Rapidly Solidified Alloys
Authors: Otooni Monde A. 
Published: March 2011

ABSTRACTAn attempt has been made to influence the trend of crystallization of a solidifying melt through the crystallization of an amorphous substrate undergoing transformation in its contact at the solid liquid interface. Two cases have been studied. In one case involving amorphous Cu60-Zr 40/Sn interface, it has been found that both textural and microstructural characteristics of the substrate, at the onset of the amorphous-crystalline transition, exert profound influence in crystallization, of the solidifying melt. High resolution electron microscopy and diffraction reveal that the preferred textural orienzation of the solidified tin is (111) at the interface and (100) far from the interface. In addition, an abundant array of edge dislocations found at the interface points to the role that these defects have played in the nucleation process of the solidifying melt. In the case of Ni60 Nb40/A1 the textural characteristics of the solidifying aluminum melt appear to be less perturbed by the crystallization effects of the substrate.
Structure and Recalescence Behavior of Underctoled Nickel-Tin Alloys
Authors: WU Yanzhong , Piccone Thomas J. , Shiohara Yuh , Flemings Merton C. 
Published: March 2011

ABSTRACTSmall nickel-tin alloy samples (3.2 g) were bulk undercooled in a Pyrex-brand borosilicate glass medium using a levitation melter. Recalescence was directly observed utilizinq a rapid thermal measurement system (resnonse time less than 10 us) consisting of two silicon photodiodes, signal amplification system, and a digital storarie device.Results of this research include: (1) measured undercoolings ranqed up to about 250 K; (2) both total solidification time and recalescence time become shorter with increasing initial undercooling; (3) in the case of hypoeutectic (Ni-25wt%Sn) alloy, a range of recalescence times was observed from 500 ms for a low undercooling (about 35 K) to 2 ms for a hiqh undercooling (about 230 K); (4) thermal profiles upon solidification of hypoeutectic comnosition alloys showed the existence of two distinct nucleation events; (5) although cooling rates before nucleation were generally low (<50 K/s), structures of fineness expected in rapid solidification processing were typically observed; (6) fineness of microstructure increases with increasing undercooling; and (7) uniform distribution of second phase was achieved by increasing undercoolina.
Oxide Dispersions in Rapidly Solidified Ti Alloys
Authors: Konitzer D.G. , Kirchheim R. , Fraser H.L. 
Published: March 2011

ABSTRACTTechniques of rapid solidification processing were used to refine a dispersion of rare earth oxides in Ti. The dispersion was produced by laser surface melting and subsequent heat treatment of a Ti-Er alloy. The second phase was identified as the rare earth oxide. The stability of the dispersion was investigated analytically and experimentally and the correlation between the analysis and experiments was shown to be very good.
Influence of Laserglaze on The Microstructure and Wear Resistance Of A Cast Nickel-Base Superalloy
Authors: Yunlong Ge , Zhuangqi Hu , Wei Gao , Changhsu Shih 
Published: March 2011

ABSTRACTInfluence of laserglaze on the microstructure and wear resistance of a cast nickel-base superalloy has been studied, which contains very high contents of refractory metals (Mo 33 wt%, W 17 wt%). After surface treatment by laserglaze the alloy structure changes extraordinarily. This change of microstructure enhances the alloy properties. Hardness of the laser melted region is evidently increased, and wear resistance and and corrosion resistance are also improved.
Rem and Rheed Studies of Pb Adsorption on Si(111)
Authors: Tanishiro Yasumasa , Fukuyamaand Masahiko , Yagi Katsumichi 
Published: March 2011

ABSTRACTStructure changes of Si(111)-Pb surfaces due to deposition and heat treatment are studied by REM-RHEED. Surface structures observed are summarized as a phase diagram. Formation of an incommensurate layer(α) and a phase transition between incommensurate structures of α and α' is described.
Surface Diffusion: Atomistics and Surface Morphology (Summary of MRS Symposium B Panel Discussion)
Authors: Grabow M. H. , Feibelman P. J. , Gilmer G. H. , Cooper B. H. , Mo Y. W. 
Published: March 2011

ABSTRACTThis paper gives some of the highlights of a panel discussion on surface diffusion held Monday, November 30, 1992 at the Fall MRS Meeting in Boston, Massachusetts. Four invited speakers discussed computer modeling techniques and scanning tunneling microscopy experiments that have been used to provide new understanding of the atomistic processes that occur at surfaces. We present a summary of each of the invited talks, indicate other presentations on surface diffusion in this proceedings, and provide a transcript of the two discussion sessions.
Scaling Description of Sub-Monolayer Epitaxial Growth
Authors: Zangwill A. 
Published: March 2011

ABSTRACTRecent experimental results aimed at the measurement of surface diffusion constants by use of scanning tunnelling microscopy and diffraction techniques have reawakened interest in the statistical properties of two-dimensional island nucleation and growth in the submonolayer regime. Classical homogeneous rate equation studies published over twenty years ago established a simple relationship among the number density of stable islands, the deposition flux, and the adatom surface diffusion constant. Recent Monte Carlo simulation studies confirm this prediction and considerably extend the scope of such a scaling description of submonolayer epitaxial growth. In this article, I review the current status of theory and experiment in this area and suggest some areas for future research.
Uhv-Mocvd Growth and in Situ Characterization of Epitaxial TiO2 Films
Authors: Chen Samuel , Gysling H. J. , Paz-Pujalt G. R. , Blanton T. N. , Castro T. , Chen K. M. , Fictorie C. , Gladfelter W. L. , Franciosi A. , Cohen P. I. , Evans J. F. 
Published: March 2011

ABSTRACTThin films of TiO2 were grown on SrTiO3 and Al2O3 using Ti(OC3H7)4 in the absence of any external oxygen source such as H2O or O2. On SrTiO3 (001), epitaxial anatase (001) formed even at temperatures (800 °C) above the anatase to rutile phase transition temperature. In situ reflection high energy electron diffraction (RHEED) was used to monitor structural evolution during growth, and the films were further characterized by Auger electron spectroscopy (AES), transmission electron microscopy (TEM), and x-ray diffraction. Reaction kinetics were monitored using mass spectrometry, and these results, combined with temperature-programmed reaction spectroscopy, gave some insight into the deposition process.
How CVD SI/GE Layer Growth is Controlled by Each one of the Reaction gas Components
Authors: Kühne H. , Kissinger G. , Zaumseil P. , Hinrich S. , Richter H. 
Published: March 2011

ABSTRACTApplying the previously derived “Three-Partial-Rates” model, CVD-Si/Ge-thin film growth and composition is described as influenced by the partial pressures of silane, germane, and hydrogen chloride. The effect of hydrogen carrier gas throughput variation is considered, as well as the density reduction of polycrystalline growth defects by the action of hydrogen chloride and hydrogen.
Photodissociation of Trimethylindium and Trimethylgallium on GaAs(100) at 193nm Studied by Angle-Resolved XPS
Authors: Shogen Satoshi , Ohashi Masafumi , Hashimoto Satoshi , Kawasaki Masahiro , Hosokawa Yasuo 
Published: March 2011

ABSTRACTThe chemisorption and photodecomposition of trimethylindium (TMIn) and trimethylgallium (TMGa) on GaAs(100) surfaces have been studied by angle-resolved X-ray photoelectron spectroscopy. The In-C bond cleavage of the adsorbed TMIn was observed when the substrate temperature was raised from 150 K to 300 K. The dissociation generates methyl radicals that react with the substrate Ga species to form the Ga-C bond. The In-C bond is also dissociated by 193 nm laser irradiation of TMIn adsorbed on the GaAs at 150 K. Irradiation at 351 nm caused no change in the X-ray photoelectron spectra since photodissociation is not due to the photoabsorption of the GaAs substrate but the photodecomposition of the adsorbed species. Similar results are observed for TMGa on a GaAs(100) substrate.
Submicron Scale Interface Roughness in Quantum Wells Observed by High-Resolution Cathodoluminescence Microscopy
Authors: Murashita Tom , Wada Kazumi , Kanisawa Kiyoshi , Inoue Naohisa 
Published: March 2011

ABSTRACTA single quantum well (SQW) is grown at a high substrate temperature and low growth rate (HTLR growth) in order to reduce interface roughness. The lateral well thickness variation in the SQW is characterized by the cathodolumincscence microscopy. It is clarified that HTLR growth can be applied to make a smooth interface for advanced devices.
Characterization of the ZnSe/GaAs Interface Layer by Tem and Spectroscopic Ellipsometry
Authors: Dahmani R. , Salamanca-Riba L. , Beesabathina D. P. , Nguyen N. V. , Chandler-Horowitz D. , Jonker B. T. 
Published: March 2011

ABSTRACTThe interface between ZnSe thin films and GaAs substrates is characterized by High Resolution Transmission Electron Microscopy and room temperature Spectroscopic Ellipsometry. The films were grown on (001) GaAs by Molecular Beam Epitaxy. A three-phase model is used in the reduction of the ellipsometric data, from which the presence of a transition layer of Ga2Se3, with a thickness of less than 1 nm, is confirmed. These results corroborate the high resolution transmission electron microscopy images obtained from the same samples.
Microscopic Morphology of Gallium Clusters on GaAs(001)
Authors: Lowes T. D. , Zinke-Allmang M. 
Published: March 2011

ABSTRACTA microscopic study of the system Ga/GaAs(001) is presented to explain the origin for different Ga cluster shapes on a single surface. The model is based on the finding that a significant fraction of the Ga clusters reaches below the GaAs surface plane and the shape of these depressions represents a minimum energy configuration if low-index planes are formed. Other metal/compound semiconductor systems may display similar shape modifications.
Phase Transition Mechanism for the Morphology of Surface Microstructures
Authors: Kleban P. H. 
Published: March 2011

ABSTRACTWe present general results demonstrating the existence of thermodynamic driving forces that effect the shape of small equilibrium regions (“droplets”), such as islands in epitaxial growth. These effects are due to critical fluctuations. They occur when the droplet, if it were infinite, would be at or near a second-order phase transition. Depending on the droplet geometry, they can lead to elongation, sharpening of “points”, or healing of “dents”. It is important to consider such effects, since in many surface preparation and modification techniques the shape of small islands can have a significant influence on the ultimate surface morphology.
Surface Waves and Strain Modulations in Si1-xGex Alloy Layers on Si
Authors: Cullis A. G. , Robbins D. J. , Pidduck A. J. , Smith P. W. 
Published: March 2011

ABSTRACTThe growth of strained, continuous Si1-xGex epitaxial alloy layers on Si can, under certain conditions, result in the occurrence of marked, small-scale layer thickness fluctuations in the form of crystallographically-aligned, interlocking ripple arrays. In the present work, combined transmission electron microscope (TEM) and atomic force microscope studies are employed to reveal the detailed nature of these surface ripples. TEM contrast studies demonstrate that well-defined, oscillatory strain variations accompany these ripple structures, the presence of which is shown to be associated with partial elastic strain-relief and lowering of the energy of die strained-layer system.
Microstructural Evolution and Coherent Islands
Authors: Drucker Jeff 
Published: March 2011

ABSTRACTMicrostructural evolution in systems containing strained islands (coherent, incoherent or both) is investigated. The growth rate of an individual island coarsening in an ensemble of strained islands is obtained by including elastic effects on surface diffusion of adatoms to and the equilibrium solubility of strained islands. For strained islands growing on a quasi-rigid substrate, coherent islands grow more slowly than incoherent islands of the same radius. Consequently, the island growth rate accelerates at the coherent to incoherent transition. The model agrees with recent experimental observations in Ge/Si(100) heteroepitaxy.
Computer Simulation Study of Film Formation Process
Authors: Sasajima Yasushi , Taya Syubo , Ozawa Satoru , Yamamoto Ryoichi 
Published: March 2011

ABSTRACTThe initial stage of film formation process was studied by 2 dimensional (2D) Monte-Carlo (MC) simulation and 3D molecular dynamics (MD) simulation. The atomistic interaction was simple pair-wise Lcnnard-Joncs potential for the 2D MC study and embedded atom potential (EAM potential) for the 3D MD simulation. The 2D MC study has revealed the dependence of film growth mode on the potential parameters that correspond to atomic size and binding energy. More realistic MD simulation has been performed using EAM potential for the three kinds of systems, Ni/Cu(111), Ag/Cu(111) and Au/Ni(111). The relaxed atomic structures of such systems showed the difference of atomic combination; coherent interface was obtained for Ni/Cu(111) system, incoherent interface with specific rotational relationships for Ag/Cu(111) andAu/Ni(111).
Strained Field of Silver Overlayers Deposited on the Reconstructed Si(111) Surface
Authors: Martinez-Miranda L. J. , Santiago-Aviles J. J. , Perez-Sandoz Raul , Carolissen Randolph , Weitering H. H. , Graham W. R. 
Published: March 2011

ABSTRACTWe have performed high resolution x-ray diffraction measurements of the strain field in UHV deposited Ag(111) films on a 7×7 reconstructed Si(111) surfaces shows a faulted epitaxial layer with a 0.4% out-of-plane strain, and a -1% in-plane strain. The strain field anisotropy is similar to that observed on epitaxial YSi2-x on Si(111), and is an unexpected result for the present system, due to the lack of a lattice match between the silver and silicon unit cells. The out-of-plane diffraction peaks have an angular distribution of 1.23°, full width at half maximum (FWHM), as determined from rocking curve measurements.