bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular Organization of Nonlinear Organic Films Laminated by Langmuir-Blodgett Method
Authors: Uchida Saburo , Chitnis Vijay T. , Furuhashi Hideo , Yoshikawa Toshio , Maeda Akinori , Sawa Goro , Kojima Kenzo , Ohashi Asao , Ochiai Shizuyasu , Uchida Yoshiyuki , Hori Masaru , Kono Akihiro
Published: March 2009

In the 21st century, the optical computation is likely to be the basic technology for
processing lots of information at high speed. The aim of the present research work is to develop optical logic gates or memory chips. For this purpose, we have examined the suitability of organic nonlinear optical dye material Vanadyl-phthalocyanine (VOPc). Large single crystals of this material have been fabricated by using Molecular Beam Epitaxy (MBE) technique. The epitaxial films were formed on the substrate under optimum operating conditions. However, the epitixial growth is observed only up to a limited thickness. Above this thickness, the films become non-epitaxial, which can be improved by annealing. The reformation of the epitaxial films has been confirmed. We have also reported the effects of the environment of high temperature on the multilayered tetra-tert-butyl-Vanadyl-phthalocyanine ((t-bu)4VOPc) films, formed by Langmuir-Blodgett (LB) method. The solvent used to dissolve ((t-bu)4VOPc) was 1,2-dichloroethane. The monolayer on the surface of the water was transferred to a glass substrate by the vertical dipping method. If the multilayered stack is too thick, the molecular arrangement of the film may get disturbed. The improvement in the molecular arrangement of the LB films was examined and confirmed by measuring it’s nonlinear optical susceptibility, using Maker Fringe Method. Monolayer formation on
water surface depends on the surface pressure-area isotherm. If this monolayer formation is not perfect, multiplayer stacks cannot be formed. The molecular films were aligned almost perpendicular to the substrate, as estimated from the limiting molecular area of surface pressure-area isotherm. The molecular organization of the monolayer on the substrate and the molecular structure of the multilayered ((t-bu)4VOPc) films are discussed.
Control of Grading Structure and Thermal Conductivity of Wood by Compressing Process
Authors: Obata Yoshihiro , Takeuchi Kazutoshi , Akaeda Kouichi , Kanayama Kozo
Published: March 2009

Compressed wood has different grading structure in an annual ring from one of natural wood. This paper treats the relationship between grading structures and effective thermal conductivity of natural and compressed woods. The Lorentz function and the power function are assumed as grading patterns of thermal conductivity. The grading thermal conductivity shows smaller effective thermal conductivity than the homogeneous wood with same average density. The sharper grading pattern gives much smaller effective thermal conductivity. The grading pattern of compressed wood is assumed as a model with locally compressed region. The calculated effective thermal conductivity by the model agrees with the measured thermal conductivity.
Effects of Seeding on the Formation of Large NaX Zeolite Crystals
Authors: Kim Ik Jin , Lee Hae Jin
Published: March 2009

The problem with zeolite crystals synthesized by conventional methods is that they are extremely small: their size typically varies 2 and 8 µm, To better define the structure of a zeolite, scientists need to grow crystal that are 100 to 1000 times larger. In this work, large crystals zeolite NaX with a uniform size of 50µm were grown by a continuous crystallization method from seed crystals (5-10µm) formed in a mother solution with the 3.5Na2O : Al2O3 : 2.1SiO2 : 1000H2O composition. In order to grow zeolite NaX crystals to an appropriate size by the continuous method,
the mother solution was fed into an autoclave a solution with various seed contents (3 - 20wt%); the autoclave has at 90°C and the solution was added after 7, 12, 16, 19 and 24 days or at 100°C after 7 and 9 days.
Ceramic Foams Coated with Zeolite Crystals
Authors: Snijkers Frans M.M. , Mullens Steven , Buekenhoudt Anita , Luyten Jan , Vandermeulen W.
Published: March 2009

Ceramic foams can be used as filters, dust collectors, light weight components and
catalyst carriers. They can be produced by a variety of techniques. The performance of ceramic foams will be strongly improved when their mechanical properties are improved. For this reason, we produced ceramic foams both by a modified reaction bonded (RB) replica technique and by gel casting. With both methods, reticulated foam structures with enhanced mechanical strength were
obtained. Zeolites are a special type of materials that are characterized by high catalytic properties. They can be brought on a structured carrier by dip and slurry coating. Nevertheless, in situ coating has as main advantage that the support is used as the base for nucleation. This results in the formation of a chemical bond between the zeolite crystals and the support. The goal of this contribution is twofold: at first we demonstrate how Al2O3 foams with improved mechanical strength can be produced both by the modified RB-alumina replica technique and by gel casting. Secondly, it is shown that these ceramic foams can be coated with (silicalite) zeolite crystals by insitu crystallization from a precursor sol. The two-layer material combinations have been characterized with FESEM, XRD, CT (computer assisted tomography), IA (Image Analysis) and by mechanical tests.
TiO2 Based Films Prepared by Sol-Gel Method for Advanced Water Treatment
Authors: Barau A. , Crışan Maria , Gartner Măriuca , Danciu V. , Cosoveanu V. , Marian I. , Anastasescu M. , Zaharescu Maria
Published: March 2009

In the present work, iron doped TiO2 films were prepared by sol-gel method. An
extensive study by varying the dopant quantity (0, 0.7, 1.4, 5 % wt Fe2O3 related to TiO2), the type of substrate (glass or ITO coated glass) and annealing temperature (300 and 500°C) was performed. The sol-gel process evolution was studied by viscosity measurements and the unsupported gels were analyzed by thermal analysis (DTA/TGA) and IR spectroscopy. The deposited films were
characterized by spectroellipsometry (SE). The catalytic activity of the films was determinate by measuring the degradation rate of the salicylic acid used as a model organic substance. A complex influence of the investigated parameters on the photocatalytic properties of the TiO2 based films was established.
A Multiscale Framework for Elastic Deformation of Functionally Graded Composites
Authors: Yin H.M. , Sun L.Z. , Paulino Glaucio H.
Published: March 2009

A micromechanics-based elastic model is developed for two-phase functionally graded composites with locally pair-wise particle interactions. In the gradation direction, there exist two microstructurally distinct zones: particle-matrix zone and transition zone. In the particle-matrix zone, the homogenized elastic fields are obtained by integrating the pair-wise interactions from all other particles over the representative volume element. In the transition zone, a transition function is constructed to make the homogenized elastic fields continuous and differentiable in the gradation direction. The averaged elastic fields are solved for transverse shear loading and uniaxial loading in the gradation direction.
The Effect of Grinding Residual Stresses on Contact Loading Strength Degradation in Y-TZP with Different Microstructures
Authors: Juy Alberto , Anglada Marc
Published: March 2009

The influence of grinding surface stresses in Y-TZP doped with 2.5% molar yttria on the contact loading response has been studied. It is shown that by grinding with different pressures compression residual stresses are induced in a surface layer of about 10 µm in depth. Their effect is manifested by shorter indentation cracks in ground specimens, but they recover the original lengths of annealed specimens after a surface thin layer is removed by polishing. The response to cyclic contact loading with a ball of 1.96 mm in diameter has been studied by looking to the damage that takes place below the indenter, as well as by measuring the flexure biaxial strength after 1, 103 and 105 cycles and for different load amplitudes. It is found that there is a threshold load, that is, a maximum contact load below which there is no degradation in the strength. This threshold is lower when transformability is higher and it depends on the number of contact cycles. But after a given large number of cycles, no further important additional degradation takes place. Under repeated contact loading in annealed specimens at loads for which a marked degradation in strength is detected, nucleation and growth of like-radial cracks is the main cause for the loss of strength, while for of ground specimens the extension of these defects is impeded by the compression surface residual stresses.
Appraisement of Creep Properties of 12Cr1MoV Steel by Small Punch Creep Test Method
Authors: Chen Gang , Zhai Peng Cheng , Shao Ai-Jun
Published: March 2009

The numerical simulation for the Small Punch creep (SP-C) tests is conducted using a Finite Element method. The objective of the present study is to obtain the deformation states of the SP-C specimen and to estimate the feasibility of SP-C test method for high-temperature creep properties. The emphasis is put on the relationship between the equivalent creep strain and the central deflection of the SP-C specimen. The time history of central deflection and equivalent creep strain is obtained by finite element method and the effects of the load, temperature and material properties on the relationship of central deflection and equivalent creep strain are discussed. From the numerical results, the relationship between the central deflection and the equivalent creep strain is approximately independent of load, temperature, and material properties. As a farther result, the high temperature creep properties of the 12Cr1MoV steel are appraised by numerical simulation. The
results are in good agreement with the results from the standard test method. The results indicate that the small punch test technique is an effective method for the evaluation of the high-temperature creep properties of materials.
Effective Thermal Conductivity of MoSi2/SiC Composites
Authors: Bai Guang Zhao , Jiang Wan , Wang G. , Chen Li Dong , Shi X.
Published: March 2009

Thermal conductivity of as-prepared MoSi2/SiC composites has been determined by
Laser Flash method. Interfacial thermal conductance for composites with 100nm SiC and with 0.5µm has been determined by using effective medium theory. The results of interfacial thermal conductance exhibit that both the inclusion size and the clustering of the inclusions play an important role in determining composite thermal conductivity.
Sintering Behavior of Multimodal Ceria Powder Mixtures for Fuel Cell Applications
Authors: Falk G. , Böhm N. , Wolff M. , Clasen Rolf
Published: March 2009

Sub-micrometer scaled CGO (Ce0,9Gd0,1O1,95) powder is used in order to manufacture Ni/CGO functionally graded green bodies with high green densities. Thereby the near-shape manufacturing of Ni/CGO cermets by gel casting of CGO and Ni powder mixtures and electrophoretic impregnation of sub-micro scaled ceria doped particles into a Ni/CGO mesoporous matrix is described. Solids content of dispersed suspensions is varied as well as the mixing ratio of sub-micro sized and micro sized particles. The influence on green density and sintering behavior is
investigated in order to achieve maximum CGO densities in combination with maximum ionic conductivity for potential use in SOFC. Shrinkage rates from sintering experiments with constant rates of heating (CRH) are analyzed to determine most suitable co-sintering conditions of Ni-Ni/CGO composite anode materials.
The Framework for Research and Technology Policies in Small Countries: The Case of Slovenia
Authors: Komac M.
Published: March 2009

The paper summarizes recent developments and implementation of the national science and technology policies. National as well as international environment play an important role, especially regarding threats and opportunities. Small size of the country is advantageous in terms of, for instance, possibility of establishing an uncomplicated research and innovation system, but, on the other side the country’s own resources, both financial and human, are far from being sufficient
for the creation of knowledge needed for the development of a knowledge-based society. Consequently, strong embedment in international S&T networks as well as an efficient knowledge transfer system is needed.
Conductivity of Grains and Grain Boundaries in Polycrystalline Heteropoly Acid Salts
Authors: Škipina B. , Čajkovski T. , Davidović M. , Čajkovski D. , Likar-Smiljanić V. , Mioč U.B.
Published: March 2009

In our previous work we investigated the conductivity and dielectric relaxation
phenomena in heteropoly acids and their salts. In this work, we have studied the conductivity of grains and grain boundaries in compressed powders of 12-tungstophosphoric acid (WPA) salts with univalent and bivalent ions. The method of impedance spectroscopy has been employed in the frequency range from 5 Hz to 500 kHz. We obtained grains and grain boundaries conductivities as well as corresponding activation energies. Grain conductivity in all investigated salts is always higher than the grain boundary conductivity.
The Synthesis of Silica-Coated Permalloy Nanoparticles Using a Water-in-Oil Microemulsion
Authors: Ban I. , Drofenik Miha , Makovec Darko
Published: March 2009

A water-in-oil microemulsion method was used for the preparation of silica-coated
permalloy (Ni0.80Fe0.20) nanoparticles. The particles were prepared by the reduction of their salts with sodium borohydride NaBH4 in a cationic water-in-oil (w/o) microemulsion of water/cetyltrimethyl- amonium bromide (CTAB) and n-butanol/isooctane at 25oC. According to the TEM and x-ray diffraction analyses, the synthesized material was in the form of nanoparticles. The magnetization of the silica-coated nanoparticles was lower than that of the uncoated particles, reflecting the influence of the nonmagnetic silica surface layer on the magnetization.
Bending Actuators Based on Monolithic Barium Titanate-Stannate Ceramics as Functional Gradient Materials
Authors: Steinhausen R. , Langhammer H.Th. , Kouvatov A.Z. , Pientschke C. , Beige Horst , Abicht H.-P.
Published: March 2009

In the field of applications of piezoelectric materials properties, functional gradient materials (FGM) are suitable for bending devices due to reduced internal mechanical stresses and lower production costs as well as for ultrasonic transducers because of their increased band width. This paper reports both on preparation, poling, characterization of FGM actuators, and on the description of suitable models of the poling and the bending processes. The calculations of the bending behavior show that the deflection at the end of the cantilever with a continuous gradient still reaches 2/3 of the deflection of a bimorph, whereas the maximum stress goes to zero, which is the main advantage of FGM compared to the commonly used bimorph devices. As a model system with well-defined electromechanical and dielectric properties of the homogeneous components the solid solution of BaTi1-xSnxO3 (BTS) with 0.075 £ x £ 0.15 was chosen. The FGMs approximated by a layered system with a one-dimensional gradient of the Sn-content were prepared both by successive uniaxial powder pressing and by tape casting with the doctor blade method. The chemical gradient was transformed into a gradient of the piezoelectric properties by a poling process. Several models were developed for the description of the non-trivial problem of the poling process in layered systems. The calculated data were compared with experimental results. It was shown that the very small electrical conductivity of the single layers generally cannot be neglected during the poling process and must be incorporated into more sophisticated models. The bending properties of several poled BTS structures with up to 4 layers were measured and discussed.
Resonant Raman Scattering in Strained and Relaxed InxGa1-xN/GaN Multiple Quantum Wells
Authors: Lazić S. , Calleja J.M. , Naranjo F.B. , Fernández S. , Calleja Enrique
Published: March 2009

We present resonant Raman scattering measurements on strained and relaxed
InxGa1-xN/GaN multiple quantum wells. The pseudomorphic sample does not show significant deviation of the A1(LO) phonon frequency with respect to GaN value due to a strong compensation of composition and strain effects which makes the frequency of this mode almost independent on In concentration. In contrast, the relaxed sample shows a marked decrease of the Raman frequency. Raman spectra excited in the energy range of sample emission have been recorded at room
temperature. The resonant conditions have been attained using tuneable lasers in the blue-green spectral region. Resonant profiles are significantly blue-shifted with respect to the photoluminescence emission as a result of an inhomogeneous In distribution. In relaxed multiple quantum well, the Raman shift of the A1(LO) mode and the maximum of the resonant Raman profile give a direct estimate of the In concentration and its variation range.
Crack Growth Resistance of Overaged Al-Zn-Mg-Cu Alloys
Authors: Vratnica M. , Cvijović Z. , Degischer Hans Peter , Requena Guillermo C. , Rumplmair G. , Rakin Marko
Published: March 2009

The crack growth resistance of the Al-Zn-Mg-Cu alloy forgings in overaged condition
was investigated with three industrially produced alloys, which showed differences in the microstructures governed by compositional variations. Fatigue-crack propagation experiments were conducted at ambient temperature and variations in crack growth rates (da/dN) as a function of applied stress intensity range (ΔK) were related to the characteristics of microstructures, including coarse intermetallic (IM) particles and precipitates. It appears that the crack growth rate increases systematically with an increase of the impurity level, which in turn increases the amount and size of large Fe- and Si-containing IM particles while decreases their spacing. That degradation in resistance to crack growth was attributed to the acceleration of the crack initiation and propagation by coarse IM particles were confirmed by in-situ SEM observation of the fracture process. The
observed anisotropy in fatigue behavior was caused by the anisotropy in coarse IM particle orientation.
Surface Structures Formed on AISI 420 Stainless Steel by Pulsed Laser Irradiation
Authors: Gaković B. , Trtica M. , Petrović S. , Panjan P. , Čekada M. , Samardžija Z.
Published: March 2009

The effects of TEA CO2 laser radiation on AISI 420 stainless steel and formed surface structures are studied. The laser energy density of 45.0 J/cm2 has modified the target surface. Qualitatively, the modifications of AISI 420 steel can be summarized as follows: change of color after action of one laser pulse; central zone of interaction in crater like form and periphery zone of interaction (for more than 10 laser pulses); appearance of grainy features and ablation rate of near 4 nm per laser pulse (action of 400 laser pulses); hydrodynamical effects like resolidified rim and droplets.
Investigation on the Static and Fatigue Failure of Bi-Directional Composite Pipes
Authors: Perreux D. , Thiébaud F. , Farines L. , Uskoković P.S.
Published: March 2009

The process of filament winding is particularly suited to the manufacturing of composite pipes. This paper first describes the overall process and its advantages for composite structures. Particular attention is devoted to bi-directional pipes [+j, -j]n. The static behaviour exhibits damage and plastic phenomena depending on the loading and stacking sequence. In the main part of the paper we focus our presentation on [+55, -55]n. The failure mode under tensile-internal pressure loads of bi-directional pipes is described, as well as their fatigue behaviour with the effect of several parameters (such as frequency) on the lifetime and the kinetics of damage. In particular, this paper shows that the effect of frequency is related to two phenomena: temperature and fatigue-creep coupling, which have opposing action on the lifetime.
Exciton Dispersion Law and States of Bimolecular Thin Films
Authors: Šetrajčić J.P. , Vučenović S.M. , Mirjanić D.Lj. , Sajfert V.D. , Jaćimovski S.K.
Published: March 2009

Dispersion laws and states (i.e. probability of finding) of Frankel excitons in ultra-thin molecular films are found using a well-known method of Green’s functions. Space boundaries and changes of energetic parameters on boundaries are considered as perturbations. The cubic crystalline system with complex cell consisted of two molecules (a and b), i.e. bimolecular film, was analyzed in harmonic approximation, and then compared with the results obtained for simple
cubic cell systems (i.e. monomolecular film). In both cases the energy spectra show sharp discrete levels, although the energy spectra of bimolecular films split into two zones with discrete levels. Probability of finding exciton in the mono- or bimolecular ultra-thin films is significantly influenced by the perturbation and the values of on-site energies of molecules a and b. Obtained conditions of the existence of localized exciton states at boundaries are of special interest.
Impact of Local Texture on Recrystallization and Grain Growth via In Situ EBSD
Authors: Wright Stuart I. , Field David P. , Nowell Matthew M.
Published: March 2009

While electron backscatter diffraction (EBSD) has become an established technique within materials characterization labs around the world, the technique is still relatively young and new applications are continuing to emerge. Automated EBSD or Orientation Imaging Microscopy (OIM) systems are being used in combination with other equipment within the scanning electron microscope (SEM) to perform in-situ measurements. This includes tensile stages for observing
changes in local orientation during deformation and heating stages for studying orientation changes arising during recrystallization and grain growth as well as phase transformations. In addition to these temporally three-dimensional studies, spatially three-dimensional studies can be performed by in-situ serial sectioning in microscopes equipped with both electron and focused ion beams. These in-situ techniques are briefly reviewed. The review is followed by a detailed analysis of in-situ heating experiments on copper. The movement of grain boundaries during recrystallization and subsequent grain growth are tracked. The effect of orientation relationships on grain boundary mobility and nucleation are explored. No special relationship with grain boundary mobility was observed. However, twins appear to play a significant role in the nucleation process.
Calculation of the Parent hcp Grain Orientation from Inherited Variants in the hcp to t and in the hcp to cc Phase Transformations Application to the α-γ Transformation in TiAl-Based Alloys
Authors: Humbert Michel , Dey S.R. , Bouzy Emmanuel , Hazotte Alain
Published: March 2009

The orientations of the inherited tetragonal (resp. cubic) variants are calculated from the parent hcp orientation in the case of a strict orientation relation. The numbering of the variants is proposed, as well as the misorientations between them. Conversely, a method for calculating the parent hcp orientation from a sufficient number of inherited variants is proposed. It is based on orientation correlating and orientation averaging, and it is particularly useful when the inherited variants are not exactly related to the parent orientation by a strict orientation relation or when the orientations of the inherited volumes slightly vary at different locations of the variant. The method is illustrated by considering the a to g phase transformation taking place in TiAl-based alloys
Prediction of Earing in IF Steels by Using Crystal Plasticity Finite Element Method
Authors: Choi Shi Hoon , Lee Beong Young
Published: March 2009

The effect of five ideal texture components ({001}<110>, {112}<110>, {111}<110>, {111}<112> and {554}<225>) typical in interstitial free (IF) steels on the development of ears was investigated using crystal plasticity finite element method (CPFEM). For the polycrystal model, the material behavior is described using crystal plasticity theory where each integration point in the element is considered to be a single grain of polycrystalline IF steel. The experimental earing profile for a IF steel was also compared to the earing profile predicted by CPFEM.
Quantitative Texture Analysis of Electrodeposited Line Patterns
Authors: Pantleon Karen , Somers Marcel A.J.
Published: March 2009

Free-standing line patterns of Cu and Ni were manufactured by electrochemical deposition into lithographically prepared patterns. Electrodeposition was carried out on top of a highly <111> oriented Au-layer physically vapor deposited on glass. Quantitative texture analysis carried out by means of X-ray diffraction for both the substrate layer and the electrodeposits yielded experimental evidence for epitaxy between Cu and Au. An orientation relation between film and substrate was discussed with respect to various concepts of epitaxy. While the conventional mode of epitaxy fails for the Cu-Au-system, it is shown that the experimentally observed orientation relation can be conceived as a 30º rotation of Cu (111) grown on Au (111) (rotational epitaxy).
Anisotropic Increase in Yield Strength by Straining and Baking of Bake-Hardenable Steel
Authors: Hiwatashi Shunji , Yonemura Shigeru
Published: March 2009

The yield strength was investigated in a prestrained and baked bake-hardenable sheet steel, which can increase the dent-resistance of exterior automotive body panels. Instead of a standard bake-hardenability test in which the final tensile test is in the same direction as prestrain, the strain-path effect in denting of stamped and paint-baked panels was examined by changing the direction of final tensile tests in uniaxially prestrained and baked samples. The prestrained samples showed the maximum of 0.2% proof stress at 45° to the prestrain axis and the minimum at 90°. Baking raised the minimums at 0° and 90° so that the anisotropy decreases. Furthermore, the strain path changes were characterized by a scalar product of previous and current strain-rate mode tensors. By regarding this parameter as the degree of reactivation of slip systems, the anisotropy observed after prestraining and baking was microscopically explained from the viewpoints of residual stress, crystal plasticity, and dislocation pinning.
Optical Grain Size Measurements: What is Being Measured? Comparative Study of Optical and EBSD Grain Sizes Determination in 2D Al Foil
Authors: Piazolo Sandra , Sursaeva Vera G. , Prior David J.
Published: March 2009

Reflected light optical analysis and Electron Backscatter Diffraction (EBSD) analysis have been used to m easure grain sizes in 2D Al foil samples, annealed for different times. There are significant differences in the results of the two techniques. It is shown that in Al it is possible to detect boundaries in optical images down to a misorientation angle of 7-8º. Nevertheless, in most samples the critical angle of easy etching lies above 10º. The observed differences in grain size measurements between optical analysis and EBSD analysis can be largely attributed to three
phenomena: (1) individual samples may behave slighty differently due to differences in the effectiveness of etching (2) the grain size is heterogeneous over large areas and (3) the effect of etching is not only a function of misorientation angle but also grain boundary plane. Despite these uncertainties, optical analysis seems to be reliable for analysis of processes in which mainly grain
boundaries with misorientation angle of > 10º are involved i.e. grain growth.
An EBSD Investigation on Deformation-Induced Shear Bands in Ti-Bearing IF-Steel under Controlled Shock-Loading Conditions
Authors: Lins J.F.C. , Sandim Hugo Ricardo Zschommler , Vecchio K.S. , Raabe Dierk
Published: March 2009

We report the results of the microstructural characterization of a Ti-bearing IF-steel deformed at high strain rates (» 6.104 s-1) in a split Hopkinson bar. The shock-loading tests were performed in hat-shaped specimens to induce the formation of adiabatic shear bands (ASB). The samples were deformed at 223 K and 298 K. High-resolution electron backscatter diffraction (EBSD) reveals the development of an ultrafine-grained structure within the ASB. A closer inspection reveals the presence of deformation twins in grains adjacent to the shear band. These twins bend towards the ASB suggesting that mechanical twinning occurs before the flow associated to shear banding. The results of microtexture have indicated the presence of a sharp <111> g-fiber texture in the ASB for both temperatures.
Study on the Micro Mechanism of Recrystallization Texture Formation in Cold-Rolled IF Steel Sheet
Authors: He T. , Liu Y.D. , Wu Yan , Jiang Q.W. , Wang Gang , Wang Yan Dong , Zuo Liang
Published: March 2009

An experimental setup was designed to study the recrystallization kinetics of Interstitial Free (IF) steel in this work. The 80% cold rolled IF steel foils are heated rapidly to 680°C, 730°C and 780°C by a salt bath. The recrystallization kinetic curves were obtained by the quantitative analysis of texture components, microstructures and EBSP (electron back-scattering patterns) measurements.
With the help of EBSD, the orientations of the recrystallization nuclei are determined. The growth rule of the recrystallization nuclei was analyzed statistically. The effect of nucleus orientation on the formation of the recrystallization texture was investigated.
Orientation Relationship during Partial α-γ-Phase Transformation in Microalloyed Steels
Authors: Lischewski I. , Gottstein Günter
Published: March 2009

The ferrite to austenite phase transformation in microalloyed steel was studied, with a special focus on the orientation relationship between prior ferrite and subsequent austenite. Also the role of growth selection and preferred nucleation was investigated in this context. Their effects were examined at partial phase transformation.
Texture Evolution during Direct and Reversed Hot Torsion Tests of Stabilized Ferritic Stainless Steels
Authors: Oliveira Tarcisio R. , Montheillet Frank
Published: March 2009

The study was carried out to understand the mechanisms occurring during the direct (negative shear direction) and reversed (positive shear direction) hot torsion of 11% chromium stabilized ferritic stainless steels. The behaviours induced by various types of stabilization, i.e., when either niobium, or titanium, or both niobium and titanium are used were compared. It was observed that continuous dynamic recrystallization (CDRX) operates in all materials starting at the onset of straining. Niobium has a more pronounced influence on hardening than titanium during hot deformation, which is due to solid solution strengthening and also to the reduction or stopping of grain boundary migration by solute drag effect. The D2 component, {112} < 111 > , was the major texture component at the steady state for the torsion tests carried along the negative shear direction. It was likely to be formed by a combination of strain and the growth of grains exhibiting both low stored energy and low rotation rate of the crystallographic axes. After reversion of the shear direction, i.e. during positive shear, the above major texture component is gradually changed into the D1 component, {112} < 111 > . Using the CMTP method (Continuum Mechanics of Textured Polycrystals), the stress evolution is explained by the volume fraction changes of each component at various strains, associated with their respective Taylor factors. Such simplified approach leads to a good agreement with experimental results.
Monte Carlo Modeling of Low Carbon Steel Recrystallization: Role of Thermo-Mechanical Treatment and Chemical Composition
Authors: Volovitch Polina , Caleyo F. , Baudin Thierry , Gerber Ph. , Penelle Richard , Rey Cristian
Published: March 2009

The recrystallization process of two low-carbon ferritic steels with low fraction of
alloying elements are modelled. The difference in chemical composition and initial thermomechanical treatment between these two steels can be the cause of the difference in the stored energy distribution after 40% deformation by cold rolling or plane compression simulated by Finite Element Modelling (FEM). In both cases the deformation texture is characterized by the presence of a g- fibre with a reinforcement for the {111}<112> component. The microstructure simulated by
FEM is used as initial structure for Monte-Carlo simulations of recrystallization. In these simulations, the variation in chemical composition and initial thermo-mechanical treatment is introduced by the difference in stored energy distribution while recovery, nucleation and grain growth are simulated assuming that grain boundary properties mainly depend on misorientation. Modelling results are in agreement with experimental observations: that is the presence of a g- recrystallization fibre which corresponds to the initial deformed state and the development of {111}<110> component which is not sharp in the deformation microstructure.
Texture Optimization in Non-Oriented Electrical Steels: The Role of the Goss Texture Component
Authors: Landgraf Fernando José Gomes , Da Costa Paolinelli Sebastião , Da Cunha Marco Antônio , de Campos Marcos Flavio
Published: March 2009

The non-oriented electrical steels, produced with different processing procedures, base their magnetic property improvement mainly on the increase of the Goss component. This paper relates the anisotropy of magnetic properties to texture, describes the texture evolution in both the Fully-processed and the Semi-processed classes of electrical steels.
Microstructure and Texture Control of Al-Mg Alloy Sheets by Differential Speed Rolling
Authors: Sakai Tetsuo , Yoneda K. , Osugi S.
Published: March 2009

Large shear deformation was successfully introduced in 5182 aluminum alloy sheets by 2-pass differential speed warm rolling under a high friction condition. The roll speed ratio was varied from 1.0 to 2.0. When the roll speed ratio was smaller than 1.4, shear strain increased near the surface, but the strain decreased to zero at the mid-thickness. At a roll speed ratio larger than 1.4, shear strain was introduced even at the mid-thickness, and it increased near the surface. Thus the shear strain increased with the roll speed ratio. After 2-pass differential speed rolling, a large shear strain prevailed throughout the thickness. The rolling direction of the second pass was so selected that the direction of shear deformation introduced in the second pass was similar to (unidirectional shear rolling) or opposite (reverse shear rolling) that in the first pass. A shear texture with main components of {111}<110>, {112}<110> and {001}<110> prevailed throughout the thickness, and conventional rolling textures such as {112}<111> or {123}<634> orientation were not detected in any part of thickness. The rolling direction of the second pass had little effect on the deformation texture. After recrystallization annealing, the shear texture components were retained. The intensity of the shear texture components after recrystallization was almost similar to the deformation texture. The r-value of the annealed sheet was slightly increased and the planar anisotropy of the r-value was decreased by differential speed rolling. Differential speed rolling, by which shear deformation can be introduced throughout the thickness, was thus shown to be a promising process for improving the physical and mechanical properties of rolled and annealed aluminum alloy sheets by texture control.
Anisotropic Tensile Properties at Room and Elevated Temperatures in Warm-Extruded AZ61 Magnesium Alloy
Authors: Wang Yi Nong , Huang J.C.
Published: March 2009

The texture characteristics and the relationship between texture and tensile properties at room temperature and superplasticity at high temperatures in a hot extruded AZ61 alloy are examined in this paper. After warm extrusion, the alloy exhibits a of refined grains microstructure and a sharp basal {0001} texture. The tensile properties at room and elevated temperatures in extruded with the loading axis oriented at 0°, 45° and 90° to the extrusion direction are tested. It is found that the 45° specimens exhibit has lower yield strength and higher ductility. The possible causes for mechanical anisotropy are also analyzed based on the Schmid factor calculations.
β→αs Variant Selection in Sharp hcp Textured Regions of a Bimodal IMI834 Billet
Authors: Germain Lionel , Gey Nathalie , Humbert Michel , Bocher Philippe , Jahazi Mohammad
Published: March 2009

Regions with sharp local textures, called macrozones, have been characterised in a bimodal IMI834 billet, containing 30% of primary αp grains surrounded by secondary αs colonies. It is shown that the αs colonies have been inherited according to a strong variant selection during the β→αs phase transformation. In each observed macrozone, the favoured variants have in average their c-axes in the same macroscopic direction as the αp grains. A detailed analysis of neighbouring αp grains and αs variants clearly shows that the variants favoured at β/αp boundaries are those able to share their c-axes with a neighbouring αp grain. The sharpness of such a variant selection mechanism is strongly related to the local orientation distribution of neighbouring αp/β grains at high temperature. This explains the differences in variant selection sharpness observed from one macrozone to the other.
Texture Formation during Severe Plastic Deformation
Authors: Alexandrov Igor V. , Zhilina M.V. , Scherbakov A.V. , Korshunov Alexander , Nizovtsev P.N. , Smolyakov A.A. , Solovyev V.P. , Beyerlein Irene J.
Published: March 2009

The paper represents results of computer modeling of texture formation in pure copper subjected to severe plastic deformation (SPD) realized by equal channel angular pressing (ECAP). Several polycrystalline models, namely the Taylor model, Sachs model, and self-consistent viscous plastic (VPSC) model, were applied and their predictions of texture evolution for different routes and number of ECAP passes were compared. For these calculations, simple shear deformation was used for the deformation realized by ECAP. Using the VPSC model, a single ECAP pass was revisited, but employing a 3D model of material flow, conducted by the variation-difference method, for the ECAP deformation. The influence of the inner and outer radii at the channel intersection and the friction coefficient on the homogeneity of the texture development in the cross section of the bulk ingot was investigated.
On Crystallographic Texture of As-Drawn Doped-W Wires
Authors: Yerra S.K. , Verlinden Bert , van Houtte Paul
Published: March 2009

Industrially processed doped-tungsten wires in the as-drawn condition have essentially a <110>-fibre texture with attractive mechanical properties. The main objectives of the present work are to investigate (I) if any textural changes occur as the wire diameter decreases and (II) if such changes influence the mechanical behaviour of the wire. A wire of about ∅1.5mm is drawn to about ∅0.15mm following a standard industrial route and samples were collected from five intermediate
drawing passes. Bulk texture measurements using X-radiations were then carried on the transverse sections of the wires and texture characteristics such as volume fraction of textural components and sharpness index were quantified with respect to the wire diameter. It was observed that the texture in the as-drawn wires remains chiefly the same <110>-fibre as the wire diameter decreases. However, the sharpness of texture reaches a maximum at a certain diameter and decreases with
further decrease in the wire diameter. An explanation is offered based on the concept of deformation zone geometry. An attempt was also made to determine if texture weakening has any effect on the mechanical properties of the wire at room temperature.
Accounting for Secondary Extinction in Thickness Measurement of Thin Films by X-Ray Absorption
Authors: Tomov I.
Published: March 2009

Allowing for secondary extinction (SE), a method is described for thickness
measurement of thin films by x-ray absorption. The method is tested by employing Al foils and electrodeposited Cu films detached by the substrate. The thicknesses determined by the method were in fair agreement with that ones measured by the ordinary absorption method based on using incident beam intensities. Moreover, a dependence of the SE coefficient on the transmission factor of the films was experimentally shown, and thus additional light was thrown on the nature of SE.
Determination of Intrinsic Magnetic Parameters of SmCo5 Phase in Sintered Samples
Authors: de Campos Marcos Flavio , Landgraf Fernando José Gomes
Published: March 2009

SmCo5 magnets are usually produced by powder metallurgy route, including milling, compaction and orientation under magnetic field, sintering and heat treatment. The samples produced by powder metallurgy, with grain size around 10 μm, are ideal for determination of intrinsic parameters. The first step for determination of intrinsic magnetic parameters is obtaining images of domain structure in demagnetized samples. In the present study, the domain images were produced by means of Kerr effect, in a optical microscope. After the test of several etchings, Nital appears as the most appropriate for observation of magnetic domains by Kerr effect. Applying Stereology and Domain Theory, several intrinsic parameters of SmCo5 phase were determined: domain wall energy 120 erg/cm2, critical diameter for single domain particle size 2 μm and domain wall thickness 60 Å. In the case of SmCo5, and also other phases with high magnetocrystalline anisotropy, Domain Theory presents several advantages when compared with Micromagnetics.
Effect of Heat Treatment on Microstructure of Commercial and Vacuum Sintered High Speed Steels AISI M2 and T15
Authors: Nogueira Rejane A. , Ribeiro Odília C.S. , das Neves Maurício David Martins , Salgado Lucio , Ambrozio Filho Francisco
Published: March 2009

The effect of quenching heat treatments on the microstructure of cast and worked commercial steel AISI M2 and hot isostatically pressed as well as IPEN vacuum sintered AISI T15 have been studied. The quenching treatments were carried out from 1160, 1185, 1210 and 1235°C. The average grain size, volume fraction and average size of the primary carbides M6C and MC were determined by scanning electron microscopy and by using the digital image analysis method "Quantikov". An increase in average austenite grain size with increase in quenching temperature was observed for the AISI M2 commercial steel and vacuum sintered specimens. In the case of the AISI T15 steel specimens, increase in quenching temperature did not result in an increase in average grain size, both for the commercial and the vacuum sintered steels. The average size and volume fraction of M6C and MC carbides remained unaltered with increase in quenching temperature.
Sinterability of High-Speed Steels M2, M3/2 and T15
Authors: Nogueira Romário Mauricio Urbanetto , Costa César Edil da
Published: March 2009

Hardmetal is usually processed by the conventional powder technology techniques: mix of WC + Co powders compacted and liquid phase sintering. A new method to process hardmetal parts is hereby described. Parts of WC-15%wt Co were processed by using high pressure – high temperature sintering. It was used the pressure of 5GPa, temperatures of 780-1200-1350-1400oC, and times of 2-4 minutes of sintering. Results are shown as a function of micro-structural evolution, densification, and hardness measurements.
Production, Sintering and Microstructural Characteristics of Ba2MgWO6 Ceramics
Authors: Aguiar Leonardo A. Rangel de , Lapa Camila M. , Ferreira Ricardo Arthur Sanguinetti , Aguiar J. Albino , Silva Charles L. da , Souza Dulcina P.F. , Yadava Yogendra Prasad
Published: March 2009

In the present era, high technology wireless communication and mobile communication systems require advanced ceramics as high frequency dielectric resonators. In the present work we have produced Ba2MgWO6 (BMW) ceramics and studied its structural, microstructural and mechanical properties. Ba2MgWO6 (BMW) ceramics belong to the Ba2MgTaO6 (BMT) and Ba2ZnTaO6 (BZT) ceramics family, which is well known ceramic material for the communication technology. There is little information available on materials characteristics of BMW ceramics. Structural characteristics of BMW ceramics were studied by X-ray diffractometry. Microstructural characteristics were studied by scanning electron microscopy and mechanical behavior was tested by Vickers micro-hardness tests on sintered BMW bodies. This article reports these characteristics of BMW ceramics and discusses its implications on application viability.
Sintering of a Clay Material with Granite and Marble Reject
Authors: Silva J.B. , Vieira F.A. , Acchar Wilson , Hotza Dachamir , Segadães Ana M.
Published: March 2009

The industrial use of wastes in the brick and tile industry has been intensively investigated in the last decade. This work describes a research carried out on the manufacturing of a clay material with granite and marble reject. The reject was obtained direct by from a ceramic industry from rocks which were sawed in blocks or slices. This industrial process produces a very large amount of this reject. The reject is launched in decanting lagoon, landing area or throw in river, resulting environment pollution and degradation. The reject material was investigated in function of chemical and mineralogical compositions using x-ray diffraction and thermal analysis. Granite and marble reject and clay material were mixed and uniaxial pressed. Samples were sintered in an electric furnace at temperature range from 950 to 1150º C. The experimental results (porosity, dilatometric analyses, water absorption, x-ray diffraction) are also presented. The results indicate that it is possible to use granite and marble reject in clay material without to predicate its properties.
A Low Cost ZSM-5 Zeolite Obtained from Rice Hull Ash
Authors: Fernandes A.A. , Frajndlich E.U.C. , Riella Humberto Gracher
Published: March 2009

The high pure synthetic zeolite have a large application in industry and agriculture, being nowadays in majority imported in Brazil. The biomass like rice hull ash (RHA), a rice industry waste, can be real advantageous in manufacture of different materials, since that is produced in large scale in the country. The silica extraction from RHA by alkaline leaching is a low energetic coast process and high efficiency, obtaining high pure silica with high reactive amorphous structure, very interesting for zeolite production. In this work was developed a economically feasible route for the production of high purity and crystallinity ZSM-5 zeolite, free of expensive template, starting from a low value intake, a industrial waste, producing a high value materials. The extracted silica from RHA in sodium silicate form is precipitated in the proper zeolite formation reactional mixture. The ZSM-5 have a lot of industrial applications due your high selectivity in catalytic reactions and high thermal and acid stability.