bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of Gas Phase Boron and Carbon-Containing Molecular Species at High Temperatures
Authors: Radić-Perić J.
Published: March 2009

The formation of gas phase boron and carbon containing molecular species at high
temperatures (thermal plasma) is investigated theoretically, by computing the equilibrium composition
of the gas mixture containing boron, carbon, hydrogen and argon. The calculations are performed for
the temperature range between 500 and 6000 K, B/C=1 and 2 and for the total pressure in the
system of 1 bar. Use is made of the fact that the thermal plasma is plasma in local thermodynamic
equilibrium, which makes possible theoretical determination (by employing the Gibbs free energy
data for the compounds present in the system) of its equilibrium composition. From the calculated
compositions of the investigated gas systems, presented in this paper, it was concluded that the
initial molecule for cluster formation, as a connection between individual molecules and the solid
state, in the case of the synthesis of solid boron carbide by means of thermal plasma should be the
B2C molecule.
Characterization of Insoluble Monovalent K+, Tl+ and Ag+ Salts of 12-Tungstophosphoric Acid
Authors: Todorović M.R. , Holclajtner-Antunović I. , Mioč U.B. , Bajuk-Bogdanović D.
Published: March 2009

The K3PW12O40, K2.5H0.5PW12O40, K2HPW12O40, KH2PW12O40, Ag3PW12O40 and
Tl3PW12O40 salts were synthesized and characterized by thermal analysis, IR and impedance
spectroscopy, and SEM. The physicochemical characterization of acid alkaline salts revealed the
presence of biphasic mixtures of unreacted heteropoly acid and its neutral salt. The unreacted
heteroply acid could be washed away by treating the acid salt with water.
Comparison between Different LiFePO4 Synthesis Routes
Authors: Jugović D. , Cvjetićanin N. , Mitrić M. , Mentus S.
Published: March 2009

Olivine-type lithium iron phosphate (LiFePO4) powders were synthesized applying three
different methods: solid state reaction at high temperature, ultrasonic spray pyrolysis, and
sonochemical treatment. The samples were characterized by X-ray powder diffraction (XRPD).
Particle morphologies of the obtained powders were determined by scanning electron microscopy
(SEM). It was found that structural and microstructural parameters of this material were strongly
dependent on the synthesis conditions. We present here the results obtained upon optimization of
each procedure for designing this cathode material.
Low-Temperature Synthetic Route for Boron Carbide Powder from Boric Acid-Citric Acid Gel Precursor
Authors: Kosanović Dj. , Milovanović Lj. , Milovanović S. , Šaponjić A.
Published: March 2009

Boron carbide powder was synthesized by sol-gel polycondensation of boric acid with
citric acid. The starting materials of Serbian origin were dissolved in water and mixed
homogeneously until a precomposite gel was formed, which was converted into cryogels after
freeze-drying. Pyrolysing and subsequent heat treatment of these cryogels resulted in boron carbide
materials. Characterization by nitrogen adsorption showed that the precomposite cryogels and the
composite powders were micro and mesoporous materials with large surface areas. Materials have
been analyzed by means of X-ray diffraction and scanning electron microscopy. The Rietveld
refinement was employed to get the structural information of the synthesized powder. The results
show that the obtained carbide powder is composed of nearly equiaxed particles of narrow size
distribution.
Fabrication of SiC by Carbothermal-Reduction Reactions of Sepiolite
Authors: Devečerski A. , Radosavljević-Mihajlović A. , Egelja A. , Pošarac M. , Matović B.
Published: March 2009

The objective of this manuscript was to investigate the synthesis of SiC by carbothermal– reduction
reactions of sepiolite. Sepiolite of Serbian origin and carbon (from various precursors) as a reducing
agent were used. The green bodies with various C/SiO2 ratios were carbonized at 1073 K and heattreated
at 1673 K in a controlled Ar flow atmosphere. Phase evolution and phase content were
followed as a function of C/SiO2 ratio and carbon origin. The starting materials and products were
characterized by means of XRD and SEM. The results show that sepiolite can be very effective
source for obtaining silicon carbide powders.
Reaction with Hydrogen of Micro and Nano Composites Based on Mg
Authors: Montone Amelia , Vittori Antisari Marco , Abazović N. , Grbović Novaković Jasna , Pasquini Luca , Bonetti Ennio , Fiorini Anna Lisa
Published: March 2009

Hydrogen, being a regenerative and environmentally harmless fuel, can play a crucial
role in the energetic scenario of the near future. In recent years several systems for solid-state
hydrogen storage have been investigated, among which a few metals and metal alloys show the
most promising properties. Mg and Mg-based micro and nanocomposites are widely studied for this
application owing to the high gravimetric storage capacity, even if a proper microstructure, mainly
at the material surface, has to be setup in order to overtake kinetic constraints often related to the
high surface reactivity. In this paper, we present our approach to this problem and report the main
findings. We have examined the influence on hydrogenation/dehydrogenation characteristics of
different modifications of the bulk and surface microstructure of MgH2 powders processed by ball
milling, which appears to be one the most useful methods for preparing powders suitable for
hydrogen storage.
Experimental and Theoretical Characterization of the 3D-Dopants Bias on the H Desorption of Mg Hydrides
Authors: Cleri Fabrizio , Celino Massimo , Montone Amelia , Bonetti Ennio , Pasquini Luca
Published: March 2009

Extensive electronic structure calculations, based on the density-functional theory, are
used to characterize the equilibrium properties and the behaviour under pressure of MgH2.
Moreover, substitutional solid solutions for several 3d metals (Fe, Ni, Ti, Al, Pd, Co, etc.) in MgH2
are characterized by computing both relaxed structures and solution energies. Theoretical results are
combined with experimental results on samples synthesized by ball milling. MgH2 was milled with
10 wt.% of 3d metals followed by microstructural characterization and hydrogen desorption
behaviour. Good correlation between theoretical solution energies and experimental desorption
temperatures reveals a general trend in these systems. A few notable exceptions can be detected,
which can be explained in terms of peculiarities in the experimental composite microstructure.
High Efficiency of Lutetium Silicate Scintillators, Ce-Doped LPS and LYSO Crystals for Medical Applications
Authors: Pidol L. , Viana Bruno , Bessière Aurelie , Galtayries A. , Dorenbos P. , Ferrand Bernard
Published: March 2009

The paper presents two cerium doped lutetium silicate crystals: pyrosilicate Ce:Lu2Si2O7
(LPS) and Ce: Lu2(1-x)Y2xSiO5 (LYSO). These two crystals exhibit the expected requirements for
gamma detection: high density and high atomic number, high scintillation light yield, good energy
resolution and fast response. LPS and LYSO crystals doped with cerium were grown by the
Czochralski process. The crystal growth parameters were studied and optimized. Development of
scintillators requires good understanding of the scintillation process. The location within the
forbidden band gap of the localized lanthanide energy levels is analyzed by time resolved
spectroscopy and thermoluminescence studies.
Induced Rearrangement of Liquid Crystal Caused by Aligning of Human Erythrocytes
Authors: Kamanin Alex A. , Kamanina Natalie V.
Published: March 2009

Both the aligning effect of erythrocytes in nematic liquid crystal media and the
phenomenon of induced rearrangement of pristine nematic liquid crystal have been observed.
Reasons for structuralization of the nematic liquid crystal under the action of inserted nonelectrically-
neutral biological components have been discussed. The observed effect is suggested to
be quite general and consistent with previously obtained results for nematic liquid crystal under the
action of fullerene-containing charge transfer complexes.
Effect of Hyperbranched Vegetable Oil Polyols on Properties of Flexible Polyurethane Foams
Authors: Petrović Z.S. , Javni I. , Jing X. , Hong D.P. , Guo A.
Published: March 2009

Molded polyurethane foams for car seats are based on petrochemical polyols of
molecular weight 4000-6000 and copolymer polyols containing micron size polymeric particles.
Copolymer polyols (CPP) typically constitute 30% of the mixture with the base polyol. They help
cell opening, increase load bearing and tear strength of the foams, but they are relatively expensive.
Hyperbranched polyols of petrochemical origin were used in molded foams.[1] They are solid in
the pure form and due to high crosslinking density could be incorporated at low concentration in
conjunction with copolymer polyols. Instead, we have made hyperbranched polyols which could be
a total replacement for CPP in molded foams. Six hyperbranched polyols with primary and
secondary hydroxyl groups and different hydroxyl numbers were prepared from soybean oil and
tested in flexible foams. Novel polyols were liquid even at very high molecular weights and could
completely replace copolymer polyols. Functionality of these polyols increased linearly with
molecular weight to very high values, resulting eventually in their high crosslinking power. The
effects of the type of hydroxyl groups (primary vs. secondary), hydroxyl number (from 85 to 135
mg KOH/g), and concentration (7.5-30%) in the mixture with the base polyol on foam properties
were analyzed. It was found that hyperbranched polyols could replace copolymer polyols
completely but their effect on cell morphology and mechanical properties varied with the type of
polyol and concentration.
Synthesis and Characterization of Polyacriflavine
Authors: Marjanović B. , Ćirić-Marjanović G. , Radulović A. , Juranić I. , Holler P.
Published: March 2009

New functional polymeric, semiconducting materials were synthesized by chemical
oxidative polymerization of acriflavine hydrochloride in aqueous solution at room temperature,
using ammonium peroxydisulfate as an oxidant. Polymerization products were characterized by gelpermeation
chromatography (GPC), FTIR spectroscopy, scanning electron microscopy (SEM) and
conductivity measurements. The influence of the oxidant/monomer molar ratio on the molecular
structure, molecular weight distribution and the electrical conductivity of polyacriflavines was
studied. Molecular weights approach a maximum value of ~20000. The polyacriflavine prepared by
using oxidant/monomer molar ratio 1.25 shows the conductivity of 2.8 × 10–7 S cm–1. New
substitution pattern shown by FTIR spectroscopic analysis combined with MNDO-PM3 semiempirical
quantum chemical calculations revealed N─C2 coupling reactions as dominant. The
formation of phenazine rings in ladder structured polymerization products was observed by FTIR
spectroscopy. The existence of a certain polyacriflavine crystalline structure was suggested from the
SEM micrographs.
Multilayer Composite Materials with Non-Usual Poisson's Ratios
Authors: Harkati E.H. , Azari Z. , Jodin P. , Bezazi A.
Published: March 2009

Most of usual materials exhibit Poisson's ratio comprised between 0 and 0.5. But, for
some kind of cellular materials, or for some stacking sequences of unidirectional plies, a composite
material can exhibit negative or greater than 0.5 Poisson's ratios. In this paper, a study of different
stacking sequences such as [±β/±θ]s plies made from highly anisotropic fibre pre-preg is presented.
A special computer programme has been developed for this purpose. Eighteen stacking sequences,
including the [±θ] ones, have been computed. The results show that at least one of Poisson's ratios
varies between -0.8 to +0.4. Such kind of materials may find applications for particular cases, as
their strength is significantly increased by this phenomenon.
Electrochemistry and Dynamic Ionography of Self-Propagating High-Temperature Synthesis (SHS)
Authors: Kuznetsov Maxim V. , Morozov Yuri G. , Parkin Ivan P.
Published: March 2009

The results of a new potentiometric technique for in situ diagnostics of self-propagating
high-temperature synthesis (SHS) of different complex oxides are presented. This technique is
based on electrochemical processes. The characteristic peaks attributed to the electric responses
from cation streams of alkali, alkaline-earth and some elements of group VI are discovered and the
respective routes of the corresponding chemical reactions found.
Determination of Impact Ionization Coefficients Measured from 4H Silicon Carbide Avalanche Photodiodes
Authors: Loh W.S. , Johnson C. Mark , Ng J.S. , Sandvik Peter M. , Arthur Steve , Soloviev Stanislav I. , David John P.R.
Published: March 2009

Hole initiated avalanche multiplication characteristics of 4H-SiC avalanche photodiodes have been studied. The diodes had n+-n-p SiC epitaxial layers grown on a p-type substrate. These 1 mm2 devices had very low dark currents and exhibited sharp breakdown at voltages of approximately 500V. The diodes multiplication characteristics appeared to be identical when the wavelength of the illuminating light from the top varied from 288 to 325nm, implying that almost pure hole initiated multiplication was occurring. The multiplication factor data were modelled using a local multiplication model with impact ionization coefficients of 4H-SiC reported by various authors. The impact ionization coefficients extracted from submicron devices by Ng et al. were found to give accurate predictions for multiplication factors within the uncertainties of the doping levels. This result suggests that their ionization coefficients can be applied to thicker bulk 4H-SiC structures.
Interplay between Surface and Grain Boundary in Sintering
Authors: Wakai Fumihiro
Published: March 2009

Three-dimensional numerical simulation of sintering was performed to illustrate the interplay between surface and grain boundary in particle scale. The shrinkage during sintering can be described as a motion of the center of mass by the force acting between particles, that is, the sintering force. When a particle interacts with several neighbor particles, the sintering force on the particle is a vector sum of forces acting through grain boundaries with neighbors. A particle changes its own shape through interaction with neighbor particles, then, the coordination number affects particle motion.
Computer Simulations of Kinetics and Texture of Recrystallisation by a 3-D Potts Monte Carlo Model
Authors: Fjeldberg Egil , Marthinsen Knut
Published: March 2009

In the present work computer simulations using a 3-D Potts Monte Carlo model are demonstrated and discussed as a tool to study the effects of a number of parameters related to the deformation conditions as well as process and material parameters related to the nucleation and growth conditions of recrystallisation, such as e.g. second phase particles, which may influence the kinetics and texture of recrystallisation. The MC simulations have been combined with a deformation texture model to provide the deformation structure from which the recrystallisation nucleates and models which provide the relative proportions of certain nucleation mechanisms and their orientation spectrum. All together this gives a simulation tool which allows for a multitude of numerical experiments and the possibility to study parameter relationships which are often not easily available from experiments. The potential of such a simulation tool is discussed in terms of a few generic examples.
Grain Growth Behavior and Characteristics of Multiphase Ceramic Composites Fabricated by Organic-Inorganic Solution Technique
Authors: Lee Sang Jin
Published: March 2009

Multi-component ceramic composites consisting of two, three and four phases, based on duplex microstructures of zirconia and alumina, were fabricated by a polymer complexation route employing polyethylene glycol (PEG) as a polymeric carrier. The polymer complexation route provided porous and soft powders and they were sintered after a simple ball milling process. In this study, the microstructures and flexural strengths of the multi-component (Al2O3-ZrO2-Y2O3-SrO) ceramic composites were examined on the processing variations of mole ratio and sintering temperature. The composites showed various grain morphologies according to the sintering temperature, and flexural strength of 410 MPa was obtained in the Al2O3·ZrO2·0.5Y2O3·0.4SrO composite sintered at 1600 °C for 1 h. In particular, needle-shape grains were observed in the four-component composites sintered at 1500 °C.
Specific Phenomena in Severe Plastic Deformation Processed SUS310S Austenitic Stainless Steel Powder
Authors: Fujiwara Hiroshi , Iwahashi Yasuro , Ohta K. , Ameyama Kei
Published: March 2009

Mechanical Milling (MM) is a Severe Plastic Deformation - Powder Metallurgy (SPD-PM) process which enables to produce a nano grain structure. A BCC layer with a nano grain structure appeared in the vicinity of the MM powder surface. Conventional cold work at room temperature never induces a strain-induced-martensitic-transformation in the SUS310S stainless steel. Therefore, a BCC layer formation from austenitic matrix is a specific phase transformation, and is attributed to the rise of the grain boundary energy by the nano grain formation. The hardness of this surface layer has approximately 540Hv, while that of the inner area has about 290Hv. As the MM powder anneals at 333K for 300s, the hardness of surface and inner area decreases to approximately 470Hv and 280Hv, respectively. Result of such a large hardness decrease in the surface of MM powder after annealing at near the room temperature indicates an existence of a huge number of defects, such as vacancy and interstitial atom, by the SPD-PM Process.
Removal of Total Organic Carbon from Aqueous Phenol Solution Using Photocatalytic ZnO Nanopowders Prepared by Solution Combustion Method
Authors: Park Sung , Lee Ju Hyeon , Yoo Kang , Park Hye Jung , Chung Yun Joong , Lee Jae Chun
Published: March 2009

ZnO nanopowders were prepared by Solution Combustion Method (SCM). The ZnO
nanopowders synthesized using Zn(OH)2 and glycine as an oxidant and a fuel (with fuel/ oxidant
ratio, F/O=0.8), showed excellent crystalline and photocatalytic characteristics. To confirm
photocatalytic activities of the prepared ZnO powder, total organic carbon (TOC) was tried to remove
from aqueous phenol solution. Surprisingly, SCM ZnO nanopowder shows 1.6 fold higher
destruction rates of the organic pollutant than P-25 TiO2 nanopowder which is known as a kind of
standard photocatalyst.
In Situ Annealing of Severe Plastic Deformed OFHC Copper
Authors: Scheriau Stephan , Vorhauer A. , Pippan Reinhard
Published: March 2009

A pure OFHC copper is subjected to severe plastic deformation (SPD) by a well defined high pressure torsion process at ambient temperature. The change in microstructure of samples deformed to different strains, up to ε=64, is investigated in-situ, during annealing at 170°C, within a scanning electron microscope. The spatial distribution of nucleation sites changes significantly with increasing strain from nucleation at triple junctions and grain boundaries to a random distribution of sites for von Mises equivalent strains beyond ε=4. The resulting mean size of recrystallized grains is about 6.75 times larger than the mean microstructural size of the corresponding as-deformed state. For strains larger than ε=16 the recrystallized microstructure appears to be independent of preceding strain. A detailed investigation of the nucleation of recrystallized grains following very large strains shows that certain microstructural elements are favoured as nuclei and were particularly taken into account.
Recrystallization Behaviour of an Austenitic High Mn Steel
Authors: Bracke Lieven , Verbeken Kim , Kestens Leo , Penning Jan
Published: March 2009

The recrystallization behaviour of a cold rolled austenitic Fe-Mn steel is studied to explain the fine grained final microstructure. Thorough investigation of the kinetics, the microstructure and the texture evolution during recrystallization showed that the fast recrystallization kinetics is responsible for the final microstructure, while an oriented nucleation mechanism determines the texture evolution. The reason for the fast recrystallization kinetics is the low amount of recovery prior to recrystallization, resulting in a high driving force for the latter.
On the Relationship between Pseudoelasticity and Texture Evolution in Ti-26Nb-0.5Si Alloy
Authors: Kim Won Yong , Kim Han Sol
Published: March 2009

Texture and cyclic tensile behavior of Ti-26Nb-0.5Si (denoted as atomic percent) alloys in which the microstructures were varied by quenching, cold rolling and recrystallization heat treatment were investigated in order to understand the relationship between pseudoelastic behavior and texture formation. Three phase mixtures consisting of bcc-structured β phase, orthorhombic structured α" phase and hcp-structured intermediate ω phase were characterized to display the constituent phases. The volume fraction of constituent phases was found to be insensitive to the given materials processing. Two-stage yielding, one at low stress with low strain hardening rate and the other one at high stress with high strain hardening rate, appeared to exhibit a characteristic flow behavior in the present alloys. It is revealed that stress-induced martensite transformation resulting in two-stage yielding was closely associated with pseudoelasticity. On the basis of texture analyses, we have suggested that pseudoelasticity of the present alloys is hindered by the development of {001}<110> rotated cube component.
Crystallographic Texture in Low Alloy TRIP Steel
Authors: Park Seong Jun , Suh Dong Woo , Oh Chang Seok , Kim Sung Joon
Published: March 2009

Low alloy transformation induced plasticity (TRIP) steels have a complex microstructure consisting of ferrite, bainite and retained austenite. Their excellent mechanical properties are ascribed to the martensitic transformation of retained austenite during plastic deformation. In the present contribution, the crystallographic texture of fcc and bcc phases in TRIP steels was measured by means of orientation mapping. The austenite texture was close to a typical rolling texture of fcc metals. For bcc phase, the effects of orientation and grain size on the distribution of pattern quality were investigated. The texture of transformation product phase was separated by grain size. The transformation texture showed stronger α fiber including {113}<110> component than the recrystallization texture. It showed a good agreement with a transformation texture predicted by Kurdjmov-Sachs (KS) relationship without any variant selection.
Texture and Boundary Characteristics of Severely Deformed and Recrystallized Copper
Authors: Davies Chris H.J. , Cao Wen Quan , Gu Cheng Fan , Lapovok Rimma , Pereloma Elena V.
Published: March 2009

Oxygen-free high conductivity copper was subjected to room temperature equal channel
angular extrusion of 8 passes using route Bc. The resulting ultra-fine grain copper was then rolled to
thickness reductions of up to 96.5% at liquid nitrogen temperatures. Annealed coarse grained copper
was rolled to the same strain at room temperature for comparison. Samples from the two routes
were isochronally and isothermally annealed, and the microstructure and texture evolution studied
by electron back scattered diffraction and x-ray diffraction.
Annealing of the ultrafine grained copper led to the development of a strong rotated cube texture
from a texture in the rolled material dominated by the Brass component. In contrast the more
commonly observed cube texture was found after annealing of the coarse-grained sample.
Accompanying the rotated cube texture was the development of a large fraction of boundaries with
rotation angle/axis close to 60° <111>.
Comparison of Grain Structures and Textures in AA5754 Aluminum Alloy Sheets Processed by Room Temperature Rolling and Rolling with Liquid Nitrogen
Authors: Jin Hai Ou , Wu Pei Dong , Lloyd David J.
Published: March 2009

Two AA5754 sheets have been processed by cold rolling with 83% thickness reduction,
one at room temperature and another with liquid nitrogen as coolant. The sheets were subsequently
annealed at 220-275°C for 1 hour. The development of grain structure and texture was studied by
optical microscope, scanning electron microscopy (SEM), X-ray diffraction and electron
backscatter diffraction (EBSD) in SEM, and the mechanical property by micro-hardness testing. It
has been demonstrated that the as-rolled sheets have the same micro-hardness, but the grain
structures and textures are very different. Compared to the sheet processed with liquid nitrogen, the
one rolled at room temperature has stronger shear texture and finer grain structure.
Processing of Multi-Layered Al-Al(Sc) Hybrid Sheet by Accumulative Roll Bonding
Authors: Quadir M. Zakaria , Al-Buhamad O. , Ferry Michael
Published: March 2009

A high-purity Al alloy and a supersaturated Al-0.3wt.% Sc alloy were accumulative roll bonded (ARB) at 200 °C to generate 0.5 mm gauge sheet consisting of 32 alternating layers of Al and Al(Sc). The material was subsequently annealed for 6h at 350 °C. The deformation and annealed microstructures were investigated using transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD). The deformation microstructure composed primarily of lamellar bands of unequal fineness with shear bands and deformation bands being additional substructural features in the Al(Sc) layers. The high strain deformation generated Al layers containing lamellar boundaries separated by a large fraction of high angle grain boundaries, thereby creating the ideal microstructure for continuous recrystallization. Annealing of the as-deformed material generated a hybrid microstructure consisting of alternating layers consisting of ~20 0m grains produced by continuous recrystallization (Al layers) and a lightly recovered substructure (Al(Sc) layers); the latter were highly resistant to recrystallization due to precipitation of nanosized Al3Sc particles during annealing.
Understanding Dynamic Recrystallization Behavior through a Delay Differential Equation Approach
Authors: Lee Jong K.
Published: March 2009

During hot working, deformation of metals such as copper or austenitic steels involves
features of both diffusional flow and dislocation motion. As such, the true stress-true strain
relationship depends on the strain rate. At low strain rates (or high temperatures), the stress-strain
curve displays an oscillatory behavior with multiple peaks. As the strain rate increases (or as the
temperature is reduced), the number of peaks on the stress-strain curve decreases, and at high strain
rates, the stress rises to a single peak before settling at a steady-state value. It is understood that
dynamic recovery is responsible for the stress-strain behavior with zero or a single peak, whereas
dynamic recrystallization causes the oscillatory nature. In the past, most predictive models are based
on either modified Johnson-Mehl-Avrami kinetic equations or probabilistic approaches. In this work,
a delay differential equation is utilized for modeling such a stress-strain behavior. The approach takes
into account for a delay time due to diffusion, which is expressed as the critical strain for nucleation
for recrystallization. The solution shows that the oscillatory nature depends on the ratio of the critical
strain for nucleation to the critical strain for completion for recrystallization. As the strain ratio
increases, the stress-strain curve changes from a monotonic rise to a single peak, then to a multiple
peak behavior. The model also predicts transient flow curves resulting from strain rate changes.
Formation of Ultrafine Grained Ferrite by Warm Deformation of Tempered Lath Martensite in Low Alloy Steels
Authors: Poorganji Behrang , Yamaguchi Takuto , Maki Tadashi , Miyamoto G. , Furuhara Tadashi
Published: March 2009

Microstructure change during warm deformation of tempered lath martensite in Fe-2mass%Mn-C alloys with different carbon contents in the range between 0.1 and 0.8mass%C was investigated. Specimens of the alloys after being quenched and tempered at 923K for 0.3ks were compressed by 50% with a strain rate varying from 10-3 to 10-4s-1 at 923K. EBSD analysis of the deformed microstructures has revealed that fine equiaxed ferrite (α) grains surrounded by high-angle boundaries are formed by dynamic recrystallization (DRX). As carbon content increases, the DRX α grain size decreases. This could be attributed to the change in volume fraction of the cementite (θ) phase as boundary dragging particles. The sub-micron θ particles can suppress the coarsening of the DRX α grains by exerting a pinning effect on grain boundary migration. Furthermore, the fraction of recrystallized region increases by increasing carbon content, presumably due to a decrease in the martensite block width as an initial α grain size and a larger volume fraction of hard second phase (θ) particles. Both of these should increase inhomogeneous plastic deformation which promotes the recrystallization. It seems that continuous DRX is responsible for the formation of ultrafine α grains in the tempered lath martensite.
Abnormal Grain Growth in Metals
Authors: Dennis J. , Bate Pete S. , Humphreys John F.
Published: March 2009

Grain growth may occur in two forms, normal grain growth, characterized by a constant grain size distribution during growth, and abnormal grain growth, where one or more abnormally large grains may form in the microstructure. The presence of abnormally large grains in an otherwise uniform microstructure may be detrimental to the mechanical properties of a polycrystalline structure. Little is understood of the exact cause of abnormal grain growth. The annealing conditions leading to the onset of abnormal grain growth have been investigated via a series of grain growth experiments carried out on an Al-4wt%Cu alloy. The structure of which consisted of equiaxed grains (<8μ) pinned by a fine dispersion of sub-micron second phase particles, which may dissolve upon annealing. Minority texture components may experience accelerated growth due to a higher energy and mobility compared to the surrounding grain structure. The combination of these two events may result in the abnormal growth of some grains. SEM imaging and EBSD data has then made it possible to characterize the influence of particle dissolution and grain boundary misorientation on the onset of abnormal grain growth. The stability of ‘island grains’ found to exist internally in abnormally large grains has also been investigated in relation to the misorientation relationship and localized second phase volume fraction found there. There was only weak evidence of special misorientation relationships between the island grains and the abnormally large grains in which they exist, and although there was evidence of an enhanced fraction of pinning particles at island grain boundaries, this was also true of boundaries in general. The larger size of island grains is their dominant characteristic, and grains which become island grains may have been incipient abnormal grains.
Physical Metallurgical Aspects of Texture Control by Thermo-Mechanical Processing of Low-Carbon Steel Sheet
Authors: Kestens Leo , Petrov Roumen H.
Published: March 2009

The present paper presents an overview of present and future tools which can be used by the steel manufacturer in order to control the texture of the finished sheet product. The major solidstate- transformation processes (phase transformation, plastic deformation and recrystallisation) playing a role during thermo-mechanical processing will be addressed. The physical mechanisms that give rise to the appearance of specific texture components will be discussed in detail. In addition to current state-of-the-art process technology the potential of innovative processes will be described such as accumulative roll bonding (ARB). The present paper will also pay attention to the particular role of surface textures as an additional degree of freedom allowing to control the sheet texture with the potential to enhance the {001} or {110} fibre textures for magnetic applications.
A New Approach to Grain Boundary Engineering for Photovoltaic Polysilicon by Unidirectional and Rotational Solidification
Authors: Watanabe Tadao , Kido Kota , Tsurekawa Sadahiro , Kawahara Koichi
Published: March 2009

A new approach to grain boundary engineering for photovoltaic polysilicon has been attempted using a new processing method of unidirectional and rotational solidification from the melt, in order to control the grain boundary microstructure and to produce desirable bulk electrical properties. The effect of grain boundary microstructure on bulk electrical properties of polysilicon can be more precisely evaluated by introducing a new parameter “directional grain boundary density (DGBD)” in connection with basic knowledge of structure-dependent grain boundary electrical properties, the grain boundary character distribution (GBCD) and grain boundary geometrical configuration which can be experimentally determined by Orientation Imaging Microscopy (OIM). We report the usefulness of this approach to development of high performance polysilicon.
Effect of Sintering Additive Composition on Grain Boundary Structure in Liquid-Phase-Sintered Silicon Carbide
Authors: Kim Young Wook , Lee Je Hun , Kim Doh Yeon
Published: March 2009

Both the presence and absence of an amorphous intergranular film (IGF) between the SiC grains have previously been reported in liquid-phase-sintered SiC ceramics (LPS-SiC). The dominant factor(s) responsible for the grain boundary structure in LPS-SiC has not been clearly revealed. In the present study, LPS-SiC ceramics containing different compositions of sintering additives were fabricated and characterized with respect to their grain boundary structure, using both scanning and transmission electron microscopy. The results suggest that the sintering additive composition plays a dominant role in the evolution of grain boundary structure in LPS-SiC.
Comparison of Deformation Structure of Lath Martensite in Low Carbon and Ultra-Low Carbon Steels
Authors: Morito S. , Ohba T. , Maki Tadashi
Published: March 2009

The microstructural development of cold-rolled lath martensite structure in the low
carbon steels and ultra-low carbon steels are studied and compared. In low carbon steel of
as-quenched specimens, very thin austenite films exist at boundaries of adjacent laths, but do not
exist in ultra-low carbon steel. After cold rolling for the low carbon steel, the lamellar dislocation
cells, irregularly bent laths and kinked laths regions are frequently observed and, in some instances,
the disappearance of initial lath boundaries is observed. The existence of retained austenite films
suggests that the lath boundaries rarely disappear during cold-rolling in the low carbon steel.
Direct Measurement of Titanium Pipe Diffusion Coefficients in Sapphire
Authors: Nakagawa Tsubasa , Sakaguchi Isao , Shibata Naoya , Matsunaga K. , Mizoguchi Teruyasu , Yamamoto Takahisa , Haneda Hajime , Ikuhara Yuichi
Published: March 2009

The diffusion behavior of Ti3+ along basal dislocations in sapphire has been investigated
by SIMS technique. High-density unidirectional dislocations were introduced by the
high-temperature mechanical deformation, and Ti3+ ions were subsequently diffused along the
dislocations. The SIMS diffusion profiles clearly showed diffusion tail due to the short circuit
diffusion along the dislocations called pipe diffusion. Lattice diffusion coefficient and pipe
diffusion coefficient of Ti3+ at 1300°C were measured to be 1.0±0.2×10-19 [m2/sec] and 2.0±0.6×
10-13 [m2/sec], respectively.
A Model for Lamellar-Rod Eutectic Transition
Authors: Liu Shan , Lee J.H. , Trivedi R.
Published: March 2009

Critical experiments in Al-Cu hypo-eutectic alloys have been carried out in capillary samples in
order to establish the lamellar/rod eutectic transition condition. It is shown that this transition occurs
over a range of compositions. Physics of the diffuse nature of this transition is proposed and the
dynamics of the transition is shown to give a specific geometric relationship between the lamellar
and rod spacing at the transition. A model of lamellar/rod eutectic transition is established that
incorporates the dynamic nature of this transition and the anisotropy in interfacial energies.
Welding of Fine Metal Particles by Using a Tungsten Needle and Measurement of the Strength of the Joints
Authors: Konno Takeshi , Egashira Mitsuru , Kobayashi Mikihiko
Published: March 2009

Gold particles several tens of micrometers in size were welded onto a gold substrate. High
voltages of 4 kV or more were applied to a tungsten needle in contact with the particle on the substrate
at a very low contact pressure. The particle was welded to the substrate in an instant with sparks. The
needle was then retracted to 20 !m above the particle and a high voltage of about 2kV was applied to
the needle. An electric discharge between the needle and the substrate enveloped the particle, and the
joint was strengthened. The joint strength was measured, and the fractured surface was examined by
scanning electron microscopy and scanning laser microscopy. The mechanism of joint strengthening
is discussed. It is clear that an inert gas flow during the electric discharge is necessary to strengthen
the joints.
Synthesis of Ultrafine Particles of Iron and Iron Nitride by Evaporation of Iron in Gas Mixtures of Argon and Ammonia or Argon and Nitrogen
Authors: Yokoyama Seiji , Saito Katsuyoshi
Published: March 2009

As a series of fundamental study on the gas evaporation method, a levitation-melted iron
was evaporated in the gas mixtures of argon + ammonia, argon + nitrogen to synthesize ultrafine particles of iron
nitride that got attention as one of the magnetic materials. The particles that were obtained in the gas
mixture of argon and nitrogen were α-Fe. But nitrogen was chemisorbed on the surface of the particle,
because nitrogen content in the particles was larger than the solubility of nitrogen in iron. The particles that
formed in the mixed gas of argon and ammonia were Fe4N. The mean size of the particles of iron nitride
was approximately 60 nm. The formation ratio of iron nitride was about 86 %.
Process and Practice of EAF with De-P Hot Metal Charging for Melting Stainless Steel
Authors: Zhu Fang Yi , Chi He Bing , Jiang Xing Yuan , Mao Wei Dong
Published: March 2009

The article introduce the process of Electric Arc Furnace with Dephosphorized hot metal
charging for melting stainless steel in Baosteel stainless steel Branch. Based on the practice of
production, The main factors affecting the process of EAF with De-P HM charging are theoretically
analyzed, such as using oxygen, the material charging and making slag. The optimization of hot metal
charging can advance the use of chemical and physical energy, reduce the consumption of power. The
optimization of using oxygen can increase the use of chemical energy. The optimization of material
charging can reduce the oxidation of Cr. Making foamy slag can advance the transformer capacity
and the use of power. Based on the character of the process EAF with De-P HM charging for Melting
Stainless Steel, EAF productivity increased were reached with application of integrated control
theory on EAF process in Baosteel stainless steel branch.
Preparation of Chain-Like Carbon Nano-Tubes Film and its Field Emission Properties
Authors: Wang Zhi Qian , Gao Jin Hai , Yao Ning , Zhang Bing Lin
Published: March 2009

Chain-like Carbon Nano-tubes films have been synthesized by microwave plasma
enhanced chemical vapor deposition (MWPECVD). The titanium-coated ceramic substrate was
placed in a stainless steel reaction chamber of MPCVD system. Prior to deposition, The substrates
were grinded with SiO2
powder with Fe dopant . The mixture gas of methane (CH4) and hydrogen
(H2) was introduced into the chamber. The flow rates of CH4/H2 were controlled at 14/100 sccm by
mass flower, respectively. The total pressure in the chamber was kept at 6.2kPa during the deposition.
The microwave power of 1700w, worked at a frequency of 2450Mhz, was applied during deposition.
The deposition time was only 1minute. The nano-structure of the deposited films was analyzed by
SEM, TEM and Raman spectroscopy. The chain-like nano-tubes randomly distributed on the
substrates. The nano-tubes are multi-wall with diameter of about 60 nm. The field electron emission
characteristics of the Chain-like Carbon Nano-tubes films were measured under the vacuum of
10-5Pa. The low turn-on field of 0.74V/μm and emission current density of 8.5mA/cm2 at electric field
2.9V//μm were obtained. The mechanism of its field emission properties was also discussed.
Investigation of Aluminum Content on the Properties of Sol-Gel-Derived Zinc Oxide Thin Films
Authors: Xue Shu Wen , Zu Xiao Tao
Published: March 2009

This paper reports that ZnO:Al films were deposited onto glass substrates by sol-gel
process. Al/Zn atomic ratio varied in a wide range from 0 ~ 20%. The structural and optical properties
were investigated by X-ray diffraction (XRD) and optical transmittance, respectively. X-ray
photoemission spectroscopy (XPS) was used to investigate the elemental compositions. XRD results
showed that ZnO films remained c-axis-orientated when Al/Zn atomic ratio was below 20% and the
grain size decreased with increasing Al content. The optical transmittance showed that the optical
bandgap of ZnO films blueshifted with increasing Al/Zn atomic ratio from 0-20%. XPS
measurements showed that the binding energy of O1s increased with increasing Al content.
Pulsed Closed Field Unbalanced Magnetron Sputtering (P-CFUBMS) Deposited TiC/a:C Thin Films
Authors: Lin Jian Liang , Mishra Brajendra , Pinkas Malki , Moore John J.
Published: March 2009

TiC/a:C nanocomposite thin film has proven to be a worthy material selection as a thin
film for tribological applications due to its low coefficient of friction, good wear resistance and high
hardness. In the current study TiC/a:C thin films with carbon concentration near 55-62 at % were
deposited via pulsed closed field unbalanced magnetron sputtering (P-CFUBMS) in pure argon
atmosphere with different substrate bias voltages and onto 440C stainless steel substrate with
different substrate roughness. It was found that the TiC/a:C film hardness and elastic modulus were
increased from 18.5 GPa to 33.8 GPa by increasing the substrate bias from floating to -150 V.
However higher substrate bias can also decrease the film tibological properties. The substrate
roughness has a strong effect on TiC/a:C film wear behavior. When the Ra (Mean surface
roughness values) is less than 110 nm, the COF values are in low range (0.18-0.28). Further
increase the Ra value to above 300 nm will result in a higher COF (>0.33). Films deposited on
higher surface roughness substrate need longer time to reach the sliding equilibrium state.
A Study on Formability of a Polyimide Film by Using Visco-Elasticity Measurement and Hot-Embossing Tests
Authors: Youn Sung Won , Suda Kazumi , Takahashi Masaharu , Maeda Ryutaro
Published: March 2009

This study explores the dynamic mechanical properties (e.g., storage shear modulus, loss
tangent and shear viscosity) and formability of a polyimide film by visco-elasticity measurement and
hot-embossing tests. The variations of storage shear modulus, tangent delta and the shear viscosity
were measured as a function of the temperature for two frequencies. As a polyimide goes through its
glass transition, it exhibits dramatic decreases in shear modulus and viscosity as well as the peak of
tangent delta, and continues to show strong dependence on frequency and temperature. Moreover, the
filling characteristics (e.g., surface appearance, replicated depth and surface roughness) of polyimide
were investigated by hot-embossing tests at different temperatures using a mold with an aspect ratio
of 2.5:1.
Cracking of Aluminum Nitride Film on Stainless Steel Substrate at Elevated Temperature
Authors: Nishijima Dai , Tabaru Tatsuo , Akiyama Morito
Published: March 2009

Aluminum nitride (AlN) thin films formed on the heat-resistant alloy substrates were
heated to 1100K. Cracking was observed in the AlN film formed on the stainless steel substrate
(SUS430), while no crack was seen in that on the nickel-base superalloy substrate (IN750X). The
electrical impedance measurements, X-ray diffraction analysis and finite element method calculation
have been conducted to discuss the relationship between the cracking and the stress introduced into
the AlN films. The AlN film cracking would be significantly affected by grain refinement of AlN.
Polymer Thin Films Prepared by RF Magnetron Sputtering of PTFE on NiTi Alloys
Authors: Li Li , Zi Fang Tao
Published: March 2009

Fluorocarbon polymer thin films on NiTi alloys possess extremely potential prospect. In
this paper, the preparation of thin films on NiTi alloys by radio-frequency (RF) magnetron sputtering
from polytetrafluoroethylene (PTFE) targets under argon is introduced. Sputtered fluorocarbon thin
films on NiTi alloys are characterized by means of atomic force microscopy (AFM), X-ray
photoelectron spectroscopy (XPS) and attenuated total reflection Fourier transform infrared
spectroscopy (ATR-FTIR) and their basic properties, especially structure and morphology, are
revealed.
Industrial Application in 2014 T6 Aluminum Alloys Having High Corrosion and Weather Resistant by Anionic Resin Coating with Mirror Luster
Authors: Hara M. , Matsuda K. , Iwai T. , Kihara M. , Yamauchi W. , Takigawa Yorinobu , Higashi Kenji
Published: March 2009

A new surface treatment technology for the aluminum alloys that exhibits not only high corrosion and weather
resistance but also good mirror luster has been developed. By performing electrolytic permeation, the
improved corrosion resistance and weather resistance while maintaining a high mirror luster was achieved for
an aluminum alloy A2014-T6. The high strength aluminum alloys featuring high corrosion and weather
resistance have been available for industrial products. Then the claim number of the products by A2014 T6
aluminum alloy has been reduced sharply to almost zero level in comparison with a past. A few applications
and the development of the processing in industrial scale in A2014 T6 aluminum alloy will be presented.
Small-Scale Resistance Spot Welding of Zr Based Glassy Alloys
Authors: Fukumoto Shinji , Fujiwara Kana , Yokoyama Yoshihiko , Murakami Yoshihiro , Yamamoto Atsushi
Published: March 2009

Resistance microwelding is an important joining process used in the fabrication of
miniature instruments. The small-scale resistance spot weldability of Zr based glassy thin sheet alloys
was investigated. Metallic glass sheets were successfully welded and amorphous structure was
maintained in both weld nugget and heat affected zone. Joint strength that is evaluated by shear
breaking force increased as the welding current increased, resulting from nugget growth. Fractured
surface showed typical vein pattern.
Structure of Zr-Cu and Zr-Ni Liquid Alloys Studied by High-Energy X-Ray Diffraction
Authors: Mizuno Akitoshi , Kaneko T. , Matsumura Seiichi , Watanabe Masahito , Kohara Shinji , Takata Masaki
Published: March 2009

In order to obtain an insight into the high glass-forming ability of bulk metallic glasses, we
have analyzed liquid structures of the Zr-Cu and the Zr-Ni binary alloys with different compositions.
High-energy (E = 113 keV) x-ray diffraction experiments were carried out for the liquid alloys
levitated by a conical nozzle levitation (CNL) technique. While a peculiar shoulder on the second
peak was observed in the structure factors of the Zr-Cu liquid alloys, those of the Zr70Ni30 and the
Zr50Ni50 liquids exhibit an asymmetric shape of the second peak. In addition, it was found that the
effect of concentration variation in the liquid Zr-Ni alloys was significantly different from that of the
liquid Zr-Cu alloys. The liquid structure analyses using the reverse Monte Carlo (RMC) simulation
have clarified that a degree of the short-range correlation between the constituents in the liquids
affects substantially the glass-forming ability of the binary Zr alloys.