bluuebunny/crossref_metadata_2025 huggingface dataset:
Shear Texture Formation during High-Strain Torsion of Titanium Aluminides
Authors: Cao G.H. , Klöden Burghardt , Oertel C.G. , Skrotzki Werner , Garbe U. , Rybacki E. , Brokmeier Heinz Günter
Published: March 2009

Ti-47Al-4(Cr, Nb, Mn, B) samples with different initial grain structures and fibre textures were deformed in torsion at 1000 °C under hydrostatic pressure of 400 MPa in a Paterson type rock deformation machine at a maximum constant strain rate of 2*10-4 s-1. The microstructure was investigated by transmission electron microscopy (TEM). Local texture measurements as a function of shear strain were done with high-energy synchrotron radiation. During shearing due to dynamic recrystallization the initially lamellar structure breaks down into a fine-grained globular structure with a g grain size in the order of 5 µm. The shear texture developed consists of <110> and {110} inclined to the shear direction and shear plane, respectively. The microstructure and texture development is discussed.
Rolling Texture of ECAP Processed Al and Cu
Authors: Kuśnierz Jan
Published: March 2009

The orientation distribution functions of conventionally prepared and pre-deformed copper and aluminium up to ı = 7.2 by the Equal-Channel Angular Pressing mode C, and then cold rolled up to 95 % area reduction have been analyzed in the paper. The rolling texture of conventionally prepared coarse-grained copper was characterized by {011}<3-11> component, whereas that of small-grained copper was characterized by {351}<1-12>. However, both components were present in copper pre-deformed up to ı = 7.2 by ECAP technique. In the ECAP pre-deformed aluminium the perfecting of the {113}<12-1> component of the rolling texture followed the increase of deformation. The texture has been discussed in relation with mechanical properties and structure observations.
The Effect of Thermal Treatments on the Annealing Behaviour of Oxygen-Vacancy Complexes in Irradiated Carbon-Doped Silicon
Authors: Londos Charalamos A. , Antonaras G.D. , Potsidi M.S. , Misiuk Andrzej , Emtsev Valentin V.
Published: March 2009

Cz-grown, carbon-doped silicon samples were irradiated by fast neutrons. We investigated the annealing behaviour of oxygen-related defects, by infrared spectroscopy. We studied the reaction channels leading to the formation of various VmOn defects and in particular the VOn defects formed by the accumulation of oxygen atoms and vacancies in the initially produced by the irradiation VO defects, as the annealing temperature ramps upwards. We mainly focused on bands appearing in the spectra above 450 oC. A band at 1005 cm-1 is found to be the convolution of two bands at 1004 and 1009 cm-1. The latter band has the same thermal stability with the 983 cm-1 of the VO4 defect and therefore is also attributed to this defect. The former band has the same thermal stability with three other bands at 965, 1034 and 1048 cm-1. These four bands may be attributed to VOn (n=5,6) defects, although other VmOn complexes are also potential candidates. Furthermore, we found that pre-treatments of the samples at 1000 oC, with or without the application of high hydrostatic pressure lead to an increase in the concentration of the VO2, VO3 and generally VOn defects in comparison with that of the untreated samples.
Evolution of Hydrogen Related Defects in Plasma Hydrogenated Crystalline Silicon under Thermal and Laser Annealing
Authors: Ma Yue , Huang Yue Long , Job Reinhart , Düngen Wolfgang , Fahrner Wolfgang R.
Published: March 2009

Boron doped [100]-oriented Cz Si wafers are hydrogenated with a plasma enhanced chemical vapor deposition setup at a substrate temperature of about 260 °C. In-situ Raman spectroscopy is applied on samples under thermal and laser annealing. It is found that different Si-H species have different stabilities. The most stable one is the Si-H bond at the inner surfaces of the platelets. The dissociated energy of Si-H bonds is deduced based on the first order kinetics. It is found that the hydrogen atoms which are released during annealing are trapped again by the platelets and passivate the silicon dangling bonds at the inner surfaces of the platelets or form H2 molecules in the open platelet volume, possibly relating to the basic mechanism of the hydrogen-induced exfoliation of the silicon wafer and the socalled “smart-cut” process.
Interstitial Carbon Related Defects in Low-Temperature Irradiated Si: FTIR and DLTS Studies
Authors: Khirunenko Lyudmila I. , Pomozov Yu.V. , Tripachko N.A. , Sosnin Mikhail G. , Duvanskii A.V. , Murin L.I. , Lindström J. Lennart , Lastovskii Stanislav B. , Makarenko L.F. , Markevich Vladimir P. , Peaker Anthony R.
Published: March 2009

The evolution of radiation-induced carbon-related defects in low temperature irradiated oxygen containing silicon has been studied by means of Fourier transform infrared absorption spectroscopy (FTIR) and deep level transient spectroscopy (DLTS). FTIR measurements have shown that annealing of interstitial carbon atom Ci, occurring in the temperature interval 260-300 K, results in a gradual appearance of a number of new absorption bands along with the well known bands related to the CiOi complex. The new bands are positioned at 812, 910.2, 942.6, 967.4 and 1086 cm-1. It has been found that the pair of bands at 910 and 942 cm-1 as well as another set of the bands at 812, 967.4 and 1086 cm-1 display identical behavior upon isochronal annealing, i.e. the bands in both groups appear and disappear simultaneously. The disappearance of the first group occurs at T = 285-300 K while the second group anneals out at T = 310-340 K. These processes are accompanied by an increase in intensity of the bands related to CiOi. It is suggested that intermediate states (precursors) are formed upon the transformation from a single (isolated) Ci atom to a stable CiOi defect. The results obtained in DLTS studies are in agreement with the FTIR data and show unambiguously the formation of CiOi precursors with slightly lower activation energy for the hole emission as compare to that for the main CiOi state.
Impact of Hydrogenation on Electrical Properties of NiSi2 Precipitates in Silicon
Authors: Vyvenko O.F. , Bazlov N.V. , Trushin M.V. , Nadolinski A.A. , Seibt Michael , Schröter Wolfgang , Hahn George T.
Published: March 2009

Influence of annealing in molecular hydrogen as well as of treatment in hydrogen plasma (hydrogenation) on the electrical properties of NiSi2 precipitates in n- and p-type silicon has been studied by means of deep level transient spectroscopy (DLTS). Both annealing and hydrogenation gave rise to noticeable changes of the shape of the DLTS-peak and of the character of its dependence on the refilling pulse duration that according to [1] allows one to classify the electronic states of extended defects as “band-like” or “localized”. In both n- and p-type samples DLTS-peak in the initial as quenched samples showed bandlike behaviour. Annealing or hydrogenation of n-type samples converted the band-like states to the localised ones but differently shifted the DLTS-peak to higher temperatures. In p-type samples, the initial “band-like” behaviour of DLTS peak remained qualitatively unchanged after annealing or hydrogenation. A decrease of the DLTS-peak due to precipitates and the appearance of the peaks due to substitutional nickel and its complexes were found in hydrogenated p-type sample after removal of a surface layer of 10-20µm.
Defect Engineering in Ion Beam Synthesis of SiC and SiO2 in Si
Authors: Kögler Reinhard , Mücklich A. , Kaschny J.R. , Reuther H. , Eichhorn F. , Hutter H. , Skorupa Wolfgang
Published: March 2009

Different methods of defect engineering are applied in this study for ion beam synthesis of a buried layer of SiC and SiO2 in Si. The initial state of phase formation is investigated by implantation of relatively low ion fluences. He-induced cavities and Si ion implantation generated excess vacancies are intentionally introduced in the Si substrate in order to act as trapping centers for C and O atoms and to accommodate volume expansion due to SiC and SiO2 phase formation. Especially the simultaneous dual implantation is shown to be an effective method to achieve better results from ion beam synthesis at implantation temperatures above 400oC. For SiC synthesis it is the only successful way to introduce vacancy defects. The “in situ” generation of vacancies during implantation increases the amount of SiC nanoclusters and improves crystal quality of Si in the case of SiO2 synthesis. Also the pre-deposition of He-induced cavities is clearly advantageous for the formation of a narrow SiO2 layer. Moreover, in-diffusion of O by surface oxidation can substitute a certain fraction of the O ion fluence necessary to obtain a buried homogeneous SiO2 layer.
The results show that defect engineering for SiC and SiO2 synthesis is working. However, the implementation of a single action is not sufficient to achieve a significant improvement of ion beam synthesis. Only an optimized combination of the different versions of defect engineering can bring about pronounced better results.
Magnetic-Field-Induced Modification of Properties of Silicon Lattice Defects
Authors: Makara V.A. , Steblenko L.P. , Kolchenko Yu.L. , Naumenko S.M. , Patran O.A. , Kravchenko V.M. , Dranenko O.S.
Published: March 2009

A possibility of magnetic-field-induced modification of structural defects in silicon crystals is studied. It is shown that magnetic field action essentially affects the structuredependent properties of Si (mechanical and electrophysical)
On the Effect of Lead on Irradiation Induced Defects in Silicon
Authors: David Marie-Laure , Simoen Eddy , Claeys Cor , Neimash V.B. , Kras'ko M. , Kraitchinskii A. , Voytovych V. , Kabaldin A. , Barbot Jean François
Published: March 2009

Different group IV impurities (Pb, C, and Sn) have been introduced in the melt during the growth of n-type Czochralski silicon. The samples have been irradiated with 1 MeV electrons to a fluence of 4x1015cm-2. The irradiation-induced defects have been studied by Deep Level Transient Spectroscopy (DLTS). It is shown that the formation of one of the irradiation-induced deep level is avoided by the Pb-doping. This level is located at 0.37 eV from the conduction band edge (EC) and shows an apparent capture cross-section of 7x10-15cm2. In addition, another irradiation induced deep level located at EC - 0.32 eV has been studied in more details.
Silicon Doped with Sulfur as a Detector Material for High Speed Infrared Image Converters
Authors: Astrov Yuri A. , Portsel L.M. , Lodygin A.N. , Shuman V.B. , Beregulin E.V.
Published: March 2009

The work aims at approaching the solution of the problem of developing sensitive silicon detectors for high speed IR imaging devices which are semiconductor – gas discharge systems. Among the requirements to detectors is their operation at the temperature which is somewhat higher than that of liquid nitrogen. To meet this requirement, a set of deep impurities is analyzed. It is emphasized that silicon doped with sulphur is a good choice to reach the aim. The doping of silicon with sulphur is done by the technique of high temperature diffusion. Data of the Hall measurements indicate the presence of large density of shallow donor levels in the material obtained. To compensate them, acceptors are introduced afterwards with using radiation doping techniques. Testing of the fabricated detectors in the converter setup shows that they provide imaging of IR fields of temperature T ~ 270 0C with the temporal resolution in the order of 3 µs.
Use of the Nitride to Reduce High-K Secondary Effects in Submicron MOSFETs
Authors: Amhouche Y. , Rais K.
Published: March 2009

The aim of this work is to study the physical obstacles introduced by the use of high-k MOSFETs structures and discuss basic problems associated with high-k candidates currently investigated such as low carrier mobility and parasitic interfacial layers and to present other ways to reduce the undesirable secondary effects when one replaces silicon with a high dielectric oxyde (high-k). We will show that use of the nitride allows reducing the effects of the interfacial layers with an acceptable reduction rate of mobility.
Electrical and Optical Characterization of Thin Semiconductor Layers for Advanced ULSI Devices
Authors: Simoen Eddy , Claeys Cor , Gaubas Eugenijus , Rafí J.M.
Published: March 2009

An overview is given of analytical techniques for the characterization of the electrical and transport parameters in thin (<1 µm) semiconductor layers. Some of these methods have been applied to the lifetime and diffusion length study in thin strain-relaxed buffer (SRB) layers of strained silicon (SSi) substrates, while a second group was dedicated to Silicon-on-Insulator (SOI) materials and devices. The employed techniques can be divided into two groups, whether a device structure (junction, MOS capacitor, MOSFET) is required or not. However, the MicroWave Absorption (MWA) technique can be used in both cases, making it a versatile tool to study both grown-in and processing-induced electrically active defects. The transport properties of SSi wafers are strongly determined by the density of threading and misfit dislocations, although the dependence of the recombination lifetime is weaker than expected from simple Shockley-Read-Hall (SRH) theory. This is related to the high injection regime typically employed, enabling the characterization of the 250-350 nm thick Si1-xGex layer only. At longer carrier decay times, multiple trapping events dominate that can be described by a stretched exponent approach, typical of disordered materials. For SOI substrates, transistor-based techniques will be demonstrated that enable to assess the generation or recombination lifetime in the thin silicon film (<100 nm). The lifetime can be severely degraded by irradiation or hot-carrier degradation. Finally, it will be shown that Generation-Recombination (GR) noise spectroscopy as a function of temperature allows identifying residual ion-implantation-damage related deep levels, which are otherwise hard to detect even by Deep Level Transient Spectroscopy (DLTS).
Thermal Stability of Ti/Mo Schottky Contacts on p-Si and Defects Introduced in p-Si during Electron Beam Deposition of Ti/Mo
Authors: Auret F. Danie , Das A.G.M. , Nyamhere C. , Hayes M. , van der Berg N.G.
Published: March 2009

In this study we have investigated the thermal stability (in the range 100 oC - 900 oC) of defects introduced in p-Si by electron beam deposition (EBD) of Ti and Ti/Mo Schottky contacts. The depletion regions below these contacts were probed by conventional deep level transient spectroscopy (DLTS) as well as Laplace (high-resolution) DLTS (L-DLTS). We have chosen Ti as the Schottky contact because the barrier height of Ti/p-Si (0.53 eV) is close to that of TiSi2/p-Si (0.50 eV) that forms after annealing at 600 – 650 oC. The Mo was added on top of the Ti in order to prevent annealing degradation. These contacts were annealed in Ar at temperatures of up to 900 oC in 100 oC steps for half-hour periods. Current – voltage (I-V) and capacitance – voltage (C-V) measurements were used to monitor the quality of the Schottky contacts. DLTS was performed after each annealing cycle to monitor the presence of the EBD-induced defects and to obtain heir electronic properties. We have found that that the Ti/Mo contacts were superior to the Ti contacts. Their (Ti/Mo) barrier height after EBD was 0.52 eV and it gradually increased to 0.56 eV after annealing at 500 oC - 600oC and then dropped to 0.50 eV annealing at 700 oC. DLTS revealed that the main defects introduced during metallization are hole traps H(0.17), H(0.23), H(0.37) and H(0.49). Annealing at 350 oC introduced an additional hole trap H(0.39). After annealing at 550 oC all defects were removed from the depletion region.
Laser Scattering Tomography on Magnetic CZ-Si for Semiconductor Process Optimization
Authors: Steinegger Thomas , Naumann M. , Kirscht F.G.
Published: March 2009

Laser scattering tomography (LST) and band-to-band photoluminescence (PL) are applied for supporting a MEMS process optimization. Process wafers are based on magnetic CZ grown silicon material. LST allows the characterization of number-size distributions of oxygen precipitates in various stages of the process flow. Precipitation is shown to be affected by the design of high-temperature anneal post initial oxidation. PL gives useful information on relative concentration level and radial distribution of recombination centers within process wafers. The initial oxidation leads to significant reduction of recombination centers. The combined LST/PL information enables valuable conclusions towards process optimization.
6H(n+)/3C(n)/6H(p+) - SiC Structures Grown by Sublimation Epitaxy
Authors: Strel'chuk Anatoly M. , Lebedev Alexander A. , Cherenkov A.E. , Kuznetsov Alexey N. , Tregubova Alla S. , Scheglov M.P. , Sorokin L.M. , Yoneda S. , Nishino Shigehiro
Published: March 2009

Investigation of the multilayer 6H(n+)/3C(n)/6H(p+)-SiC heterostructure grown by sublimation epitaxy show that the injection electroluminescence (IEL) in the green region (hνmax≈2.30-2.35eV) of spectrum is dominant. This band is close to the electroluminescence peak due to defects in 6H-SiC but also can be due to free exciton annihilation in a quantum well in 3C-SiC at the 6H/3C-SiC heterointerface. At high current the IEL peak at hνmax≈2.9 eV is found. This peak (and also two another peaks in blue part of spectra: hνmax≈2.6 eV and hνmax≈2.72 eV) can be attributed to recombination in 6H-SiC. The forward current-voltage characteristics for best structures are close to those for ideal 6H-SiC pn homostructure and characterized by abrupt breakdown. A lot of structures are characterized by barrier type excess current. Structure in the region of evident 3C-SiC inclusion is characterized by high forward and reverse excess currents.
Silicon Based Light Emitters for On-Chip Optical Interconnects
Authors: Kittler Martin , Arguirov Tzanimir , Seifert Winfried , Yu X. , Reiche Manfred
Published: March 2009

Electroluminescence of B and P implanted samples has been studied. P implantation is found to have a similar effect on light emission as B implant. The band-to-band (BB) luminescence of P implanted diodes is observed to increase by more than one order of magnitude upon rising the temperature and an internal efficiency of 2 % has been reached at 300 K. An efficiency larger than 5% seems to be reachable. The strong BB line emission at 1.1 &m is attributed to high bulk SRH lifetime. The BB line escapes from the substrate below the p-n junction. It is not due to the implantation-related defects/dislocations. The luminescence spectrum can be tailored to achieve dominance of the dislocation-related D1 line at about 1.5 &m. It is observed that a regular periodic dislocation network, formed by Si wafer direct bonding with a specific misorientation, exhibits even at 300 K only D1 photoluminescence. Such a dislocation network is believed to be a serious candidate to gain an efficient Si-based light emitter.
µ-Raman Investigations on Hydrogen Gettering in Hydrogen Implanted and Hydrogen Plasma Treated Czochralski Silicon
Authors: Düngen Wolfgang , Job Reinhart , Ma Yue , Huang Yue Long , Fahrner Wolfgang R. , Keller L.O. , Horstmann J.T.
Published: March 2009

µ-Raman measurements were carried out on hydrogen implanted, plasma hydrogenated and subsequently annealed Cz Silicon samples, respectively. In comparison to as-implanted or asplasma treated samples, in consideration of the thermal evolution, the effects of the implanted and subsequently plasma treated samples were analyzed. An enhanced trapping of molecular hydrogen in multivacancies has been observed after hydrogen implantation and subsequent plasma hydrogenation. In comparison to as-implanted samples, the intensity of the local vibrational modes (LVM) of vacancy-hydrogen complexes and silicon-hydrogen bonds are increasing.
On-Line Monitoring to Detect Third-Party Damage on Underground Natural Gas Pipelines Using Accelerometer
Authors: Nam Jae Young , Choi S.H. , Choi Jae Boong , Kim Young Jin
Published: March 2009

Even though an excavation is not under the direct control of the utility operators, it is the main cause of third-party damage on the underground natural gas pipelines. Since the damage due to third-party excavation may lead to horrible consequences, preventative techniques that can reduce the third-party damage are needed. The purpose of this paper is to introduce an on-line monitoring system using accelerometer to detect a propagating acoustic pressure pulse that is produced from the third-party damage. Also, in order to verify this system, the corresponding field tests were performed considering many third-party damage sources(breaker, hammer drilling, etc.) and signal transmission ratio of each source. From the tests, signals developed by the third-party damage sources were successfully detected with the digital filter, which can distinguish external noises at the distance of 13km. Therefore, it is expected that the system can be used as a useful tool for the third-party damage monitoring of underground natural gas pipelines
Development of Lead-Free Solder Composites Containing Nanosized Hybrid (ZrO2 + 8 mol.% Y2O3) Particulates
Authors: Nai Sharon M.L. , Wei Jun , Gupta Manoj
Published: March 2009

In this study, lead-free composite solders were successfully synthesized, with varying amount of nanosized ZrO2 + 8 mol.% Y2O3 particulates incorporated into 95.8 Sn – 3.5 Ag – 0.7 Cu solder. These composite materials were fabricated using the powder metallurgy technique involving blending, compaction, sintering and extrusion. The extruded materials were then characterized in terms of their physical properties, microstructural development, thermal and mechanical properties. Experimental results revealed that with the addition of increasing amount of reinforcements, the density values of the composite solders decreased, but there was no influence on the melting point of the composite solders. Thermomechanical analysis of the solder nanocomposites showed that the use of reinforcements lowered the average coefficient of thermal expansion of the solder material. Moreover, the results of mechanical property characterizations revealed that the addition of reinforcements aids in improving the overall strength of the nanocomposite solder. An attempt is made in the present study to correlate the variation in volume percentages of the hybrid reinforcements with the properties of the resultant nanocomposite materials.
Hydrogen Induced Phase Transformations in Austenitic-Ferritic Steel
Authors: Głowacka A. , Woźniak M.J. , Nolze Gert , Świątnicki W.A.
Published: March 2009

The hydrogen influence on the microstructure of the austenitic-ferritic Cr22-Ni5-Mo3
stainless steel was investigated. Cathodic hydrogen charging was performed electrochemically from
aqueous solution of 0.1M H2SO4 with hydrogen entry promoter addition. The aim of this study was
to reveal microstructural changes appearing during the hydrogen charging and particularly to clarify
the occurrence of phase transformations induced by hydrogen. The specific changes in both phases
of steel were observed. In the ferritic phase, strong increase of dislocation density was noticed.
Longer time of hydrogen charging leaded also to the strips and twin plates formation in ferrite
phase. In the austenitic phase, the generation of stacking faults, followed by the formation of α'
martensite was remarked.
Internal Dynamics of Norethisterone by NMR, IINS and QC Methods
Authors: Holderna-Natkaniec Krystyna , Natkaniec Ireneusz , Jurga Kazimierz , Nowak Dorota , Szyczewski Andrzej
Published: March 2009

The low-temperature inelastic incoherent neutron scattering spectrum of norethisterone was compared with that calculated by the density functional theory method. The quantum chemical calculations permitted proposing the assignment of the vibrational modes. In particular, the dynamics of the methyl group substituted at C(13) of the steroid skeleton was analysed on the basis of the neutron scattering spectra and temperature dependence of the spin-lattice relaxation time (1H NMR).
Modeling of a Mechatronic System with the AC Induction Motor Supplied by the Frequency Converter
Authors: Baskys A. , Rinkevičienė R. , Jegorov S. , Petrovas Andrius
Published: March 2009

A model of the AC induction motor, which allows us to analyze all operation modes of motor supplied by the frequency converter, has been developed. A simulation of the inverter of the frequency converter and the AC induction motor interaction on the basis of the developed motor model, using software MATLAB, was performed and a motor regenerative braking mode was investigated. The results of investigation are used for the development of fault protection of the inverter.
Dynamic Errors of CMM Probes
Authors: Kasparaitis Albinas , Šukys A.
Published: March 2009

Here are proposed methods to evaluate the accuracy of measuring heads (MH) of
coordinate measuring machines (CMM). Kinematic touch-trigger, piezoresonant touch-trigger and
scanning 3D probes are investigated as the most often being used for the 3D measurements. The
dominating errors of kinematic touch-trigger probes are expressed by the polygonal (triangular)
characteristics of their kinematics and by random dispersion of the contact forces. These features
characterize the piezoresonant touch-trigger probes as well but instability of resonance of the
system components are also presented here. Dominating error’s characteristics of the scanning
probes consist of the instability of pushing the probe stylus out of the measured surface by
dynamical forces. Some mathematical models, space error’s approximation and results of
experimental investigation of the measuring heads are presented. It may be used for the
improvement of CMM and other measuring equipment.
The Influence of Hydrostatic Extrusion on the Properties of an Austenitic Stainless Steel
Authors: Budniak Julia , Lewandowska Małgorzata , Pachla Wacław , Kulczyk Mariusz , Kurzydlowski Krzysztof Jan
Published: March 2009

The paper presents the results of investigations into the mechanical properties and tribological characteristics of 316 LVM processed by hydrostatic extrusion (HE). The mechanical properties were characterized by microhardness measurements and compression tests. The wear properties were investigated using a pin-on-disc tribometer under dry and lubricated conditions. The friction coefficient was measured as a function of the time of the wear test. The results indicate that the hydrostatic extrusion process significantly improves the mechanical properties and the wear resistance of 316 LVM stainless steel. The results are discussed in terms of the microstructural changes induced during processing by hydrostatic extrusion.
Strength of Commercial Aluminum Alloys after Equal Channel Angular Pressing and Post-ECAP Processing
Authors: Murashkin Maxim Yu. , Markushev M.V. , Ivanisenko Julia , Valiev Ruslan
Published: March 2009

The effects of equal channel angular pressing (ECAP), further heat treatment and rolling
on the structure and room temperature mechanical properties of the commercial aluminum alloys
6061 (Al-0.9Mg-0.7Si) and 1560 (Al-6.5Mg-0.6Mn) were investigated. It has been shown that the
strength of the alloys after ECAP is higher than that achieved after conventional processing. Prior
ECAP solution treatment and post-ECAP ageing can additionally increase the strength of the 6061
alloy. Under optimal ageing conditions a yield strength (YS) of 434 MPa and am ultimate tensile
strength (UTS) of 470 MPa were obtained for the alloy. Additional cold rolling leads to a YS and
UTS of 475 and 500 MPa with 8% elongation.
It was found that the post-ECAP isothermal rolling of the 1560 alloy resulted in the formation of a
nano-fibred structure and a tensile strength (YS = 540 MPa and UTS = 635 MPa) that has never
previously been observed in commercial non-heat treatable alloys.
Mechanical Spectroscopy and Relaxation Phenomena in Solids
Authors: Magalas Leszek B. , Darinskii B.M.
Published: March 2009

Mechanical spectroscopy and relaxation phenomena in solids are briefly discussed from
the viewpoint of generalized susceptibility and linear response theory. Comparison of mechanical
spectroscopy with other spectroscopic techniques is provided in the endeavour to formulate a
multidisciplinary approach to selected relaxation phenomena in solids.
Thermal Spray Manufacturing of Semi-Finished Parts for Thixoforming of Fiber and Particle Reinforced Metal Matrix Composites
Authors: Wenzelburger Martin , Nieves Alsina Maria , von Niessen Konstantin , Gadow Rainer
Published: March 2009

Processing of light-metals in semi-solid state offers some advantages regarding process
temperatures, handling of the material, but also the resulting micro-structure of the final component.
Reinforcement of light-metal components with fibers or particles can be applied in order to increase
elastic modulus and yield strength of the material as well as its wear resistance. But, the
manufacturing of metal matrix composites by thixoforging requires the supply of raw material that
shows thixotropic behavior at processing temperature and that contains a definite volume fraction of
well distributed reinforcement phase. In this work, an arc wire spray process is applied for the
manufacturing of semi-finished parts by coating of long-fiber fabrics and by deposition of ceramic
particle containing billets. The process technique is described and the suitability of thermally sprayed
matrix material for semi-solid processing is verified.
Steel Grades Adapted to the Thixoforging Process: Metallurgical Structures and Mechanical Properties
Authors: Robelet Marc , Rassili Ahmed , Fischer Dirk
Published: March 2009

Thixoforming of steel offers the advantages of casting technology in combination with
high mechanical strength that can only be achieved by forging. The progress in establishing this
technology in industry depends on the success in the development of suitable steel grades.
Recent investigations dealt with the development of steel grades that are especially adapted to the
thixoforming process. For this, alloys were developed with a lower solidus temperature and a wider
process temperature range compared to classic forging steels. In consequence, the inductive heating
process is more tolerant to inaccuracies and for a given liquid fraction the process temperature
window is easier to handle.
It is desired to obtain great degrees of deformation at rather low forming forces as these parameters
determine the size of the needed presses. This behaviour is affected by the present liquid fraction in
the slug and the heat transfer between work piece and die. It was detected that variations of the
forming force have a direct influence on the quality of the thixoformed parts.
In order to make the thixoforming technology of steels competitive versus other forming
technologies, the parts must show a favourable microstructure and thus, good in-use properties. In this
paper various solutions are compared.
The main results obtained in the optimization research, namely, the steel grades adapted to semi-solid
forming, the resulting process parameters and the mechanical properties of thixoforming parts will be
presented for two exemplary steel grades. By producing a real automotive part, thixoforging of steels
with regard to the adapted materials and to the ongoing industrial implementation of this process is
proved.
Effect of Hot-Dip Silicon-Aluminizing on the Anti-Carburization Behavior of High-Temperature-Resistant Steel HK40
Authors: Xie Fei , Morral John
Published: March 2009

High-temperature-resistant (HTR) austenitic steel HK40 is employed for being
silicon-aluminized by being hot-dipped in molten aluminum and silicon alloys and diffused
subsequently at 1200°C. The phases, microstructures and concentration for elements of interest in
the treated case are investigated by x-ray diffraction (XRD), optical microscopy (OM), scanning
electron microscopy (SEM) and energy dispersive spectrum of x-ray (EDS). The case composes of
three main zones: the former hot-dipped coating zone, inter-diffusion zone, and diffusion zone of Al
and Si, all of which contain quite higher contents of aluminum and silicon than substrate.
Pack-carburization is used for assessing the anti-carburization behavior of the treated case. The
treated case shows excellent property in hindering the inward-diffusion of carbon, even if the
former hot-dipped coating zone spalls off with only diffusion zone left. High contents of aluminum,
silicon and oxygen are still detected on surface of the silicon-aluminized specimen after
carburization. Good anti-carburization ability of the silicon-aluminized specimen is believed mainly
to be the result of the dense and stable Al2O3 and SiO2 films formed on the surface.
Numerical Simulation and Measurement of Velocity Distribution in a Gas Nitriding Furnace
Authors: Wang Jing , Chen Nai Lu , Shan Xue Xiong
Published: March 2009

During gas nitriding process, homogeneous velocity distribution is required to ensure
uniformity of gas content and temperature fields, which is one of key factors for fine processing
results. In order to understand the velocity distribution in a gas nitriding furnace, which was equipped
with a stirring motor-driven fan on top, we studied different situations with several fan motor
rotational speeds. The whole furnace was modeled by computational fluid dynamics software package
FLUENT. The fan boundary condition and standard k-ε equation are chosen for modeling to generate
better results in our case. A digital turbine anemometer is used to measurment velocities at various
places inside the furnace. Good agreements were found between simulation and measurement.
X-Ray Diffraction Analysis on Crystallite Development of Nanostructured Aluminium
Authors: Meijer Elisabeth , Armstrong Nicholas , Yeung Wing Yiu
Published: March 2009

This study is to investigate the crystallite development in nanostructured aluminium
using x-ray line broadening analysis. Nanostructured aluminium was produced by equal channel
angular extrusion at room temperature to a total deformation strain of ~17. Samples of the extruded
metal were then heat treated at temperatures up to 300oC. High order diffraction peaks were
obtained using Mo radiation and the integral breadth was determined. It was found that as the
annealing temperature increased, the integral breadth of the peak reflections decreased. By
establishing the modified Williamson-Hall plots (integral breadth vs contract factor) after
instrumental correction, it was determined that the crystallite size of the metal was maintained ~80
nm at 100oC. As the annealing temperature increased to 200oC, the crystallite size increased to ~118
nm. With increasing annealing temperature, the hardness of the metal decreased from ~60 HV to
~45 HV.
Production of Cu-Hf-Ti Bulk Glassy Composites by Mechanical Alloying and Spark-Plasma Sintering
Authors: Choi Pyuck Pa , Kim Ji Soon , Choi Hyeong Suk , Kwon Dae Hwan , Kwon Young Soon
Published: March 2009

This work reports on the production of Cu-Hf-Ti bulk glassy composites through a powder metallurgical route, i.e. by mechanical alloying and subsequent spark-plasma sintering. Powders of Cu60Hf30Cu10 and Cu60Hf25Ti15 composition were prepared using a high-energy planetary ball-mill. Both alloys nearly showed a fully amorphous structure with only a small fraction of residual HCP Hf grains left after 50 h of milling. Differential scanning calorimetry (DSC) analyses of the milled glassy powder revealed a two-stage crystallization process for both compositions. However, the released crystallization enthalpy was substantially larger for the Cu60Hf25Ti15 alloy than for the Cu60Hf30Ti10 alloy, suggesting that the former comprises a higher fraction of the amorphous phase than the latter. Both powders showed distinct glass-transition with a large super-cooled liquid region. Consolidation of Cu60Hf25Ti15 powder was carried out by means of spark-plasma sintering at applied pressures of 200 and 500 MPa, choosing a sintering temperature within the super-cooled liquid region (T = 753 K). The sintered compacts exhibited some pores and interparticle boundaries.
Influence of Oxygen Plasma Treatment on Impact Behaviors of Carbon Fibers-Reinforced Composites
Authors: Park Soo Jin , Oh Jin Seok , Lee Jae Rock , Rhee Kyong Yop
Published: March 2009

In this work, effects of the oxygen plasma on surface characteristics of carbon fibers were investigated in impact strengths of the carbon fibers-reinforced composites. The surface properties of the carbon fibers were determined by acid-base values, FT-IR, and X-ray photoelectron spectroscopy (XPS). Also, the mechanical properties of the composites were studied in impact strength measurements. As experimental results, the O1S/C1S ratio of the carbon fiber surfaces treated by oxygen plasma was increased compared to that of untreated ones, possibly due to development of oxygen-containing functional groups. The mechanical properties of the composites, including impact strength had been improved in the oxygen plasma on fibers. These results indicate that the oxygen plasma can lead to an increase in the adhesion between fibers and matrix in a composite system.
Preparation and Characterization of Epoxy/Clay Nanocomposites
Authors: Lee Young Chul , Kim Myeong Jun , Lee Yong Bong
Published: March 2009

Epoxy/clay nanocomposites have been prepared using montmorillonite (MMT) ionexchanged
with various organic cations ; hexadecyltributyl phosphonium ion, octadecyltrimethyl
ammonium ion, methyl tallow bis-2-hydroxyethyl ammonium ion and dimethyl hydrogenatedtallow
(2-ethylhexyl) ammonium ion. The resulting nanocomposites were found to show exfoliated
clay structure by using transmission electron microscopy (TEM) and X-ray diffractometry (XRD).
The flame retarding property of 5wt% clay/epoxy nanocomposites was found to be enhanced when
compared with that of the original epoxy without clay.
Hydrothermal Synthesis, Characterization and Electrocatalytic Activity of La0.8Sr0.2MnO3 Nanocubes for Oxygen Reduction Reaction
Authors: Joshi Upendra A. , Lee Jae Sung
Published: March 2009

The La0.8Sr0.2MnO3 nanocubes have been synthesized by simple precipitation
followed by hydrothermal process. The as-obtained nanocubes were characterized by
SEM, TEM, EDS, XRD and ICP-AA. The SEM and TEM images clearly showed cube
type morphology of reaction product. The XRD pattern gave evidence for the phase
purity and high crystallinity of the La0.8Sr0.2MnO3 nanocubes. The ICP-AA analysis
along with EDS confirms the stoichiometry of the product. Electrochemical activity for
oxygen reduction reaction was carried out in 1 M KOH. The oxygen reduction current
measured by cyclic voltametry showed six times higher value for nanocubes than that of
bulk catalysts of same composition.
Preparation of a Low Cost Carbon Nanotubes Field Electron Emission Thin Film and its Initial Application Research
Authors: Liu G.Y. , Zhi C.Y. , Xia Shan Hong , Zhang J.G. , Li H.Y. , Yang J.X. , Liu S. , Wang Enge G.
Published: March 2009

A large area perfect aligned carbon nanotubes (CNTs) thin film was grown directly on a stainless steel substrates by a
low cost bias-assisted hot-filament chemical-vapor deposition (BA HF-CVD) technology. The CNT’s / stainless steel field
emission array (FEA) cathode (CNT’s/FEA) has been fabricated. The field electron emission behavior of the CNT’s/FEA cathode
was characterized in a vacuum condition, a high electron emission of about 10mA/cm2 at a low electric field of 4V/μm implies
the promising the application as a cathode of the flat panel display device, so further assembled this cathode in a kind of vacuum
device, and the possibility of the operation from a flat panel character (Pictures) display tube FCT has been tested initially.
Colloidal Silica Particles with Bimodal Final Size Distribution: Ion-Induced Nucleation Mechanism
Authors: Zhang K. , Song Z.F. , Yan Y. , Chen Q.M.
Published: March 2009

Colloidal silica particles, Bimodal size distribution, Nucleation
Abstract. Colloidal silica particles with bimodal size distribution have been prepared by the
hydrolysis of tetraethylorthosilicate in alcoholic solutions of water and ammonia as catalyst.
Experimental conditions such as concentration of NaCl, amount of water and reaction temperature
were investigated to reveal the formation mechanism of the colloidal silica particles. The nucleation
process of colloidal silica particles with bimodal size distribution depends on the hydrolysis rate of
TEOS and the ionic strength of reaction media. The hydrolysis reaction is the rate-limiting step
during the nucleation process. Nucleation involving background ions generated by TEOS hydrolysis
reaction and addition of electrolyte(NaCl) is another potentially important factor for nucleation
process of electrically charged clusters. A critical value of ionic strength exists in the reaction to
form bimodal size distribution particles.
Kinetic Monte Carlo Simulation of Semiconductor Quantum Dot Growth
Authors: Zhao C. , Chen Y.H. , Sun J. , Lei W. , Cui C.X. , Yu L.K. , Li K. , Wang Z.G.
Published: March 2009

Performing an event-based continuous kinetic Monte Carlo (KMC) simulation, We
investigate the growth conditions which are important to form semiconductor quantum dot (QD) in
molecular beam epitaxy (MBE) system. The simulation results provide a detailed characterization of
the atomic kinetic effects. The KMC simulation is also used to explore the effects of periodic strain to
the epitaxy growth of QD. The simulation results are in well qualitative agreement with experiments.
Modeling of the Ionized Fluid Flow through a Cone-Shaped Nanopore
Authors: Fu Jian Zhong , Mi Xiao Bing , He Yong , Chen Zi Chen
Published: March 2009

Theoretical analysis of the ionized fluid flowing through a cone-shaped nanopore is
presented. The internal cross section of the cone-shaped channel is in the range from micro- to
nanometer and gradual change from larger to smaller than the Debye length for the ions. The model is
developed to predict the ionized fluid flow behaviors in cone-shaped micro/nanochannels. The
velocity profiles of ion flow that occur in nanopores are obtained.
Experimental and Numerical Studies on B-DNA Overstretching Transition in Presence of Sodium Ions at Physiological Temperature
Authors: Fu Hong Xia , Koh Chan Ghee , Chen Hu , Lim Chwee Teck
Published: March 2009

In this paper, the effects of Na+ concentration on the overstretching transition of B-DNA
molecule at physiological temperature are studied by both experimental and numerical methods.
Using optical tweezers, the relationship of external force and relative extension is obtained by
stretching single B-DNA molecule at 37°C. As the concentration increases from 0.909mM to
909mM, the overstretching transition force increases from 65.65 ± 1.2pN to 43.07 ± 1.2pN. An
analytical expression is derived, which shows that overstretching transition force is linear with the
natural logarithm of salt concentration.
Based on a previous model, a three-dimensional model is proposed herein and solved by
Metropolis Monte Carlo method. The bending deformation of DNA backbones, cooperativity of
base-stacking interactions, electrostatic interactions, and spatial effects of DNA double helix
structure are taken into account. Our key contribution is that the electrostatic energy is explicitly
given as a function of folding angle and Na+ concentration. A new parameter is also introduced to
account for the cooperativity of base-stacking interactions. The numerical results of this model are
in good agreement with our experimental results.
The Effects of Organic Solvent on the Electrospinning of Water-Soluble Polyacrylamide with Ultrahigh Molecular Weight
Authors: Zhao Yi Yang , Li X. , Wang C. , Li L.J.
Published: March 2009

The effects of an organic solvent on the electrospinning of water-soluble polyacrylamide
with ultrahigh molecular weight were investigated. An organic solvent, DMF, was introduced to the
polyacrylamide aqueous solution and subsequently, transparent spinning solutions were obtained.
The spinning solution was electrospun at the voltage of 10 kV and the electrospun products were
examined by scanning electron microscopy (SEM). Results indicated that all the electrospinning
products including colloidal particles, beaded fibers and smooth fibers were fabricated in the
DMF/H2O bi-component solvent and the morphology of electrospun products changed from smooth
fiber to beaded fiber with the increasing amount of DMF used.
High Pressure on Asperity Surface Caused by Nano Particles’ Behavior in Non-Newtonian Slurries
Authors: Chen H.S. , Chen Da Rong , Li Jiang
Published: March 2009

Particle’s behavior in the slurry with power-law viscosity shows great effect on the wafer
surface polishing. Hydrodynamic pressure is periodically generated on the surface asperity when
particles are passing through it. Fatigue fracture occurs under the effect of periodical pressure and it
begins from the top to the bottom of the asperity. Based on the energy-balance fracture theory, the
removal rate is calculated and it shows good agreement with experiment data.
Nano-Structured Carbon Nitride Films for Microsensor Applications
Authors: Lee J.G. , Lee S.P.
Published: March 2009

Nano-structured carbon nitride film, which is a new sensor material, has been prepared by
facing target magnetron sputter for microsensor applications. Surface morphology, surface roughness
and bonding structures of the films were investigated by EDS, SEM, AFM and FTIR spectroscopy.
The growth rate of film is about 2.2 um/hr, and grain size and RMS roughness are about 320 nm and
0.9 nm, respectively. The impedance of micro-humidity-sensor, which was fabricated by the
conventional semiconductor fabrication process including lift-off technique, changed 95.4 kΩ to 2
kΩ in the relative humidity range of 5 % to 95 %.
Composite Nanofibers for Textile Applications
Authors: Han X.J. , Huang Z.M. , Liu L. , He C.L. , Wu Q.S. , Li Yan
Published: March 2009

Functional core-shell structured composite nanofibers can be fabricated by
means of electrospinning of two polymer solvents in a coaxial, two-capillary spinneret
system. Three groups of composite nanofibers, Nylon-6(cell)/PVA(core), PC(cell)/
PU(core) and PU(cell)/Nylon-6(core), have been developed using this technique.
Morphological, structural, and mechanical characterizations are conducted for the
developed composite nanofibers and their applications as textile materials have been
explored.
Fe86.5Zr7B3Cu3.5 Nanocrystalline Ribbon Prepared by Melt – Spinning Technique without Annealing
Authors: Hu Ji Fan , Li B. , Qin Hong Wei , Zhao D.L. , Hao Y.M. , Jiang M.H.
Published: March 2009

Fe86.5Zr7B3Cu3.5 nanocrystalline ribbon can be directly fabricated by melt – spinning
technique with an appropriate quenching speed without annealing processes. The average grain size
of α-Fe for Fe86.5Zr7B3Cu3.5 as quenched ribbon prepared with a quenched speed V=40 m/s is about
10-13 nm estimated from X-ray diffraction and TEM observation. For Fe86.5Zr7B3Cu3.5
nanocrystalline as quenched ribbon (V=40m/s), the saturation magnetic induction Bs is 1.47 T,
permeability μe at 1 kHz is 25600 and saturation magnetostriction λs is -2×10-6. The
magnetoimpedance value Z/Z0 of the Fe86.5Zr7B3Cu3.5 nanocrystalline as quenched ribbon reaches
–38.32 % under H=7162 A/m. Our present results reveal a novel route to fabricate the nanocrystaline
ribbons with excellent soft magnetic properties and giant magnetoimpedance.