bluuebunny/crossref_metadata_2025 huggingface dataset:
Head-On Immobilization of DNA Fragments on CVD-Diamond Layers
Authors: Wenmackers S. , Christiaens P. , Deferme W. , Daenen M. , Haenen K. , Nesládek M. , Wagner Patrick , Vermeeren V. , Michiels L. , Van de Ven Martin , Ameloot M. , Wouters J. , Naelaerts L. , Mekhalif Z.
Published: March 2009

Synthetic diamond is regarded as a promising material for biosensors: it forms a stable platform for genetic assays and its biocompatibility opens the possibility for in vivo sensing. In this study the use of a thymidine linker for covalent DNA attachment was evaluated. Contact angle measurements provided a qualitative test of the initially oxidized surface. X-ray photoemission spectroscopy was used for further analysis of the oxides and for monitoring the effect of subsequent chemical treatments. The presence of FITC-labelled DNA was confirmed by confocal fluorescence microscopy. Enzyme linked immunosorbent assays indicated that this DNA was merely adsorbed on the diamond surface instead of covalently bound.
Effects of Annealing Condition on the Preparation of Indium-Tin Oxide (ITO) Thin Films via Sol-Gel Spin Coating Process
Authors: Han Hyun-Woong , Yun Young Hoon , Choi Sung Churl
Published: March 2009

Indium tin oxide (ITO) thin films were deposited on glass substrates via sol-gel spin coating process from a mixed solution of Indium (Ⅲ) acetylacetonate and Tin (Ⅳ) iso-propoxide. Then, ITO thin films were fired at 500°C, and then annealed at 500°C for 30 min with the sequential annealing process; VacuumN2Ar/H2, N2Ar/H2 and Ar/H2 gas. The effects of the different annealing processes on the surface morphologies and sheet resistance of ITO thin films were investigated. Sheet resistance values of ITO thin films treated under VacuumN2Ar/H2, N2Ar/H2 and Ar/H2 annealing process were 1.25 kohm/sq., 3.18 kohm/sq. and 4.92 kohm/sq., respectively. Actually, the sequential atmosphere gases and non-oxidizing gas, which were used in annealing process influenced the microstructural features or surface morphologies of ITO thin films: grain size and surface roughness. Thus, it was presumed that the sequential annealing condition influenced the densification behavior in the microstructural evolution of ITO thin films.
Time-Dependent Behavior and Fracture of Functionally Graded Thermal Barrier Coatings under Thermal Shock
Authors: Kokini Klod , Rangaraj Sudarshan V.
Published: March 2009

The thermal fracture and its dependence on time-dependent behavior in functionally graded yttria stabilized zirconia - NiCoCrAlY bond coat alloy thermal barrier coatings was studied. The response of three coating architectures of similar thermal resistance to laser thermal shock tests was considered, experimentally and computationally.
Mixed-Mode Crack Propagation in Functionally Graded Materials
Authors: Kim Jeong Ho , Paulino Glaucio H.
Published: March 2009

This paper presents numerical simulation of mixed-mode crack propagation in functionally graded materials by means of a remeshing algorithm in conjunction with the finite element method. Each step of crack growth simulation consists of the calculation of the mixedmode stress intensity factors by means of a non-equilibrium formulation of the interaction integral method, determination of the crack growth direction based on a specific fracture criterion, and local automatic remeshing along the crack path. A specific fracture criterion is tailored for FGMs based on the assumption of local homogenization of asymptotic crack-tip fields in FGMs. The present approach uses a user-defined crack increment at the beginning of the simulation. Crack trajectories obtained by the present numerical simulation are compared with available experimental results.
Finite Element Simulation of Microstresses in a Traditional FGM: The Case of Soft Tribo-Alloys
Authors: Schouwenaars Rafael , Jacobo Víctor H. , Cerrud Sara M. , Ortiz Armando
Published: March 2009

Journal bearings are graded systems with a metal-metal composite as the functional
layer. Estimation of the microscale stress distributions is used to analyse the interaction between microstructure, material properties and damage mechanisms during wear. The analysis is executed by means of simple plane-strain finite element models mimicking experimentally observed microstructures. It is found that under realistic macrosstress conditions no tensile microstresses are induced in the triboalloy and that plastic flow is inhibited by the graded structure.
Thermo-Mechanical Analysis of RLV Thrust Cell Liners with Homogeneous and Graded Coatings
Authors: Butler Daniel T. , Pindera Marek-Jerzy , Aboudi Jacob
Published: March 2009

The Higher-Order Theory for Cylindrical Functionally Graded Materials is employed to investigate the effectiveness of thermal barrier coatings in mitigating deformation mechanisms in thrust cell liners leading to experimentally observed failure modes. The results indicate that under the employed thermo-mechanical loading histories coating thickness has a great impact on temperature and deformation fields within the cooling channel wall of a thrust cell liner, with thicker coatings producing more desirable temperature and deformation fields. Functional grading of metallic substrate and coating materials does not produce improvement in terms of overall thrust cell liner performance. Further, the application of grading is potentially detrimental due to likely roughening of the thrust cell liner wall in the combustion chamber as a result of local deformations around relatively coarse inclusions. The homogenized approach to analyzing the graded coating effectiveness is incapable of capturing these localized effects, leading to erroneous conclusions.
Tribolayer Formation as a Functionally Self-Grading Process in Soft Anti-Friction Alloys
Authors: Schouwenaars Rafael , Jacobo Víctor H. , Cerrud Sara M. , Ortiz Armando
Published: March 2009

Soft anti-friction alloys are metal-metal composites used in journal bearings as a
functionally graded system. The physical processes occurring during severe wear of these products are analysed and placed within the framework of theories on tribolayer formation. A simplified analysis of the thermodynamics of the phenomena permits analysing the anti-friction properties of the alloys in terms of the activity coefficients of their constituents and indicates that during wear, a wear-resistant contact layer is formed which retards further damage.
Strength Distributions in Ceramic Laminates
Authors: Pascual Javier , Chalvet Francis , Lube Tanja , de Portu Goffredo
Published: March 2009

In this work the strength of ceramic laminates is analyzed. Two different architectures with the same surface are studied. One of them, a Al2O3 / Zr(3Y)O2 laminate, contains compressive residual stresses, the other one, a monolithic Al2O3 laminate, has no residual stresses. Residual stresses are estimated analytically on the basis of the materials properties and by an indentation technique. The influence of the residual stress on the strength distribution is investigated. Strength distributions for laminates with compressive stresses at the surface follow a Weibull distribution only under certain conditions.
Fabrication and Mechanical Properties of TZ-3Y20A /Mo Multilayer Composites
Authors: Zhang Lian Meng , Yu Li Chun , Gong Dao Ren , Shen Qiang
Published: March 2009

In the present work, TZ-3Y20A/Mo multilayer composites were prepared by sedimentation method. Appropriate settling parameters were chosen and green bodies of multilayer composites were obtained by settling TZ-3Y20A powder and Mo powder in turn according to the designed individual layer thickness. Then green laminates were hot pressed at 1773K for an hour under the pressure of 20MPa. Three-point Bending and Single Edge Notched Beam (SENB) tests were adopted to evaluate the flexure strength and fracture toughness of the samples. The results showed that, compared to TZ-3Y20A ceramics, the fracture toughness and the work of fracture increased due to the layered structure. The microstructure and crack deflection of the fracture surface of the laminated composites was also observed by optical microscopy.
Functionally Graded TiC-Based Cermets via Combustion Synthesis and Quasi-Isostatic Pressing
Authors: Martinez Pacheco M. , Stuivinga Marianne , Carton Eric , Katgerman Laurens
Published: March 2009

Experimental results on the preparation of functionally graded TiC-based cermets obtained by combustion synthesis (also known as Self-Propagating High-Temperature Synthesis, SHS) followed by quasi-isostatic (QIP) pressing in a granulate medium are presented. Pellets of TiC-Fe graded cermets are produced by stacking layers of Ti and C powder mixtures in which the content of a NiFe alloy (50 wt% Ni and 50 wt% Fe) is varied from 5 up to 25 vol %. X-ray diffraction showed that the NiFe alloy did not react with the TiC, thus preserving its special properties. Scanning electron microscopy results show a graded material with pores increasing in size towards the side with the highest ceramic fraction.
Fabrication of Al2O3-ZrO2~Ni Functionally Graded Pipes
Authors: Kobayashi H.
Published: March 2009

The fabrication of Al2O3-ZrO2~Ni functionally graded pipes has been investigated by slurry coating and pressureless sintering process. Each slurry of Al2O3-ZrO2~Ni mixture and Ni was coated in order on the Al2O3-ZrO2 pipes formed by slip casting method with those slurries. The obtained laminar green pipes were 30 mm in diameter and approximately 90 mm in length. The laminar green pipes were sintered for 2 hours at 1430°C in a vacuum. The structure of pipes fabricated by this method was optically and microscopically examined and the graded distribution was examined by an EPMA analysis of Al and Ni. The pipes with 2 layers of Al2O3-ZrO2 and Ni had crevices in the bonding interface. Some functionally graded pipes with 3 layers were free from cracks and warps without porosity, and each interface had the complete bonding.
Synthesis and Characterization of Large NaX Zeolite Crystals by Continuous Crystallization
Authors: Lee Hae Jin , Lim Hyung Mi , Kim Ik Jin
Published: March 2009

NaX zeolite crystals of 50 µm were grown by a continuous crystallization with seed crystal (10 ㎛) in a mother solution having a 3.5Na2O : Al2O3 : 2.1SiO2 : 1000H2O composition. The seed crystal morphology of NaX zeolite shows that an octahedron is formed composed of 8 equilateral triangles which have an average lattice constant of a = 24.9911 Å with a SiO2/Al2O3 molar ratio of 2.1~2.4. In order to grow crystals of zeolite X to an appropriate size by the continuous method, the mother solution was supplied with various seed contents (3~20 wt%) in an autoclave at 90°C after 7, 12, 16, 19 and 24 days.
Effect of Microwave Heating on the Synthesis of Layered Double Hydroxide
Authors: Lim Hyung Mi , Kang Mi Ra , Lee Sang Chun , Lee Seung Ho , Kim Kwang Jin
Published: March 2009

Layered double hydroxide(LDH) was synthesized from the mixture of magnesium
hydroxide and aluminum hydroxide with microwave irradiation. It has been compared with that of conventional heating method in the respect of crystallization time, structure, morphology, particle size, and its anion exchange capacity. The microwave speeded up the crystallization rate of Mg-Al- LDH so that the XRD patterns of LDH was observed from the sample after microwave hydrothermal treatment, while the crystal phase was hardly observed from that prepared by
conventional hydrothermal method before drying process. Mg-Al-LDH prepared with microwave irradiation seemed to have slightly higher Mg/Al molar ratio even with the same compositions of starting materials and the lower anion exchange capacity after 1 day exposure in 0.1N NaCl solution compared to the conventionally prepared one.
Flowability of Electrolytic Copper Powder
Authors: Pavlović M.G. , Popov K.I. , Krstić S.B. , Pavlović Lj.J. , Ivanović E.R.
Published: March 2009

The surface structure of powder particles, which allows free flow of copper powder, was examined. It has been shown that a sufficiently dense surface structure which permits free flow will be obtained if apparent density is higher than 2.2 – 2.3 g/cm3. Such a surface structure can be obtained by reversing current electrodeposition of powder at considerably lower apparent densities of powder due to selective dissolution of subparticles during anodic time of reversing current wave. The surface structure of copper powder particles is discussed and correlated with the lowest apparent density at which the copper powder can still flow.
Hot Pressing of Y2O3 Doped Si3N4 Ceramics
Authors: Bučevac D.
Published: March 2009

The effect of seeding on the microstructure and mechanical properties of hot-pressed silicon nitride was investigated by introducing large, elongated b-Si3N4 particles into an α-Si3N4 matrix. Densification and fracture toughness were followed in the presence of Y2O3 as sintering aid. The concentration of seeds varied from 0 to 5 wt%. The maximum fracture toughness was 8.0 MPam1/2 for a material with 3 wt% seeds, hot pressed at 1750oC, for 4h.
HEMT Carrier Mobility Analytical Model
Authors: Lukić P.M. , Ramović R.M. , Šašić Rajko M.
Published: March 2009

In this paper a new analytical carrier mobility model of a heterostructure unipolar
transistor, High Electron Mobility Transistor (HEMT), is presented. The influence of the two dimensional electron gas confined in a HEMT channel on the device carrier mobility, is considered. The mobility dependence on temperature is also included in the model. Advantages of this model are its simplicity and straightforward implementation. Besides, it promises to be applied to quite different types of HEMTs. The model was tested. The results derived from simulations based on the proposed model are in very good agreement with the already known experimental data and
theoretically obtained ones, available in literature.
Synthesis and Electrophoretic Deposition of an Yttrium Silicate Coating System for Oxidation Protection of C/C-Si-SiC Composites
Authors: Argirusis Christos , Damjanović Tanja , Stojanović M. , Borchardt Günter
Published: March 2009

Due to favorable chemical and mechanical properties of yttrium silicate coatings (low Young’s modulus, low thermal expansion coefficient, low evaporation rate and oxygen permeability, good erosion resistance), this material is a promising complement to SiC coatings for protecting C/C-Si-SiC composites. For the preparation of silicate powders, the Pechini method was used. As a coating method, electrophoretic deposition from stable suspensions based on isopropanol was chosen. Under controlled deposition voltage and duration, coatings of various thicknesses were deposited. The deposited layers were characterized by SEM and EDX analysis. The protectiveness of these coatings was tested by isothermal thermogravimetry.
Properties of Dispersion-Hardened Copper Made by Internal Oxidation of Prealloyed Copper Powder Containing 2.5 wt. % Al
Authors: Rajković V. , Božić D. , Vračarić D. , Romhanji E.
Published: March 2009

Prealloyed copper powder containing 2.5wt. %Al was processed in a planetary ball mill to evaluate matrix hardening due to formation of Al2O3 particles in situ by internal oxidation. After milling, the powders were heat treated in hydrogen in order to reduce copper oxide formed on particle surfaces during milling. The compacts were made by hot pressing. The examinations show that the compacts possess a good combination of high strength and high electrical conductivities. After 5h of milling the microhardness of the prealloyed compact was 3 to 4 times higher than that of the as-received electrolytic copper compacted under the same conditions, while the conductivity was 68% IACS. Also, it was found that the prealloyed compacts preserved much of the hardness after exposure to high temperature in inert atmospheres.
Effects of Fullerenol C60(OH)24 on Cytotoxicity Induced by Antitumor Drugs on Human Breast Carcinoma Cell Lines
Authors: Kojić V. , Jakimov D. , Bogdanović G. , Djordjević A.
Published: March 2009

The aims of this paper were to investigate cell growth activity of fullerenol C60(OH)24, its modulating effect on antitumor drug-induced cytotoxicity, and genotoxic influence of fullerenol at nanomolar concentrations. Human breast cancer cell lines, MCF-7 and MDA-MB-231, were treated with fullerenol at concentrations from 0.9 to 3.9 µg/ml alone or simultaneously with antitumor drugs (doxorubicin, cisplatin, taxol, and tiazofurin; IC50 concentrations) for 2 hours. Growth inhibition was evaluated by colorimetric SRB assay after recovery period of 24, 48, and 96 hours. The genotoxic examination was performed using sister chromatid exchange test and micronucleus assay, at fullerenol concentration ranging from 1 to 5 µg/ml. The fullerenol alone mildly inhibits the growth of both cell lines. Simultaneous administration of fullerenol and antitumor drugs strongly suppressed antitumor drug-induced cytotoxicity. The rate of cytotoxicity inhibition depended on fullerenol concentration, type of antitumor drug and cell line. Protection against doxorubicin and cisplatin was more pronounced than against taxol and tiazofurin. Fullerenol was not found to be genotoxic to investigated cell lines.
Rainbow Effect in Channeling of High Energy Protons in (10, 0) Single-Wall Carbon Nanotubes
Authors: Borka D. , Petrović S. , Nešković N.
Published: March 2009

We investigate theoretically the angular distributions and the rainbows of 1 GeV protons channeled in the ropes of (10, 0) single-wall carbon nanotubes. The rope length is varied between 0.53 and 5.29 µm. The angular distributions of channeled protons are generated using the numerical solution of the proton equations of motion in the transverse plane and the computer simulation method. We use Molière’s expression for the continuum interaction potential of the proton and the rope. The rainbow lines in the impact parameter plane and scattering angle plane are also determined numerically. We show that these lines ensure the full explanation of the angular distributions. The possible applications of these results are discussed.
Evolution of Internal Stresses during the Plastic Deformation of IF Steel and Their Correlation with Crystal Orientation
Authors: da Fonseca Joao Quinta , Bate Pete S.
Published: March 2009

Due to their polycrystalline nature, metals develop intergranular stresses during elastic and inelastic deformation. These stresses are thought to play a role in the fatigue properties of metals and to significantly affect residual stress measurements. The development of intergranular stresses during deformation of interstial free steel was modelled using crystal plasticity finite element modelling. Predictions were compared with measurements made using fast synchrotron diffraction and good qualitative agreement was found. Effects of mesh size and shape, element packing and neighbourhood on the predicted mean elastic strains and their variance were
investigated.
Micromechanisms Involved in Grain Boundary Engineering
Authors: Pinto Andre Luiz , Costa Viana Carlos Sergio da , de Almeida Luiz Henrique
Published: March 2009

Grain boundary engineering has been applied to different materials in order to increase properties particularly sensitive to intergranular phenomena. This work analyses the micromechanisms that allow the control of the amount of special boundaries which respect coincidence site lattice theory. α-brass, a lead alloy, Inconel 625 and Inconel 600 were submitted to different thermomechanical treatments and were analyzed via electron backscatter diffraction in order to characterize their grain boundaries. The occurrence of thin twins in some crystal directions during the deformation step seems to determine the results obtained as well as strain induced boundary migration.
In Situ High Temperature Texture Characterisation in NiTi Shape Memory Alloy Using Synchrotron Radiation
Authors: Paula Andersan S. , Mahesh Karimbi Koosappa , Braz Fernandes Francisco Manuel , Martins Rui Miguel S. , Cardoso A.M.A. , Schell Norbert
Published: March 2009

The aim of the present experiment was to analyse the structural evolution during annealing of Nickel-Titanium (Ni-Ti) SMA subjected to different thermomechanical treatments. As structural evolutions are accompanied by the changes in preferential orientations, pole figures were employed to study the in-situ conditions.
Grain Boundary Energy and Grain Growth in Highly-Textured Al Films and Foils: Experiment and Simulation
Authors: Barmak Katayun , Archibald W.E. , Kim Jihwan , Kim Chang Soo , Rollett Anthony D. , Rohrer Gregory S. , Ta'asan Shlomo , Kinderlehrer D.
Published: March 2009

Relative grain boundary energy as a function of misorientation angle was measured in a cube-oriented, 120 µm-thick Al foil and in a <111> fiber-textured, 1.7 µm-thick Al film using a multiscale analysis of the grain boundary dihedral angles. For the Al foil, the energies of low-angle boundaries increased with misorientation angle, in good agreement with the Read-Shockley model. For the Al film, two energy minima were observed for high-angle boundaries. Grain growth was studied in 25 and 100 nm-thick films that were annealed at 400 °C for a series of times in the range of 0.5 to 10 h. For the 100 nm-thick film, grains approximately doubled their size (equivalent circular diameter) before grain growth stagnated. The steady-state distributions of reduced grain area for two-dimensional, Monte Carlo Potts and partial differential equation based simulations showed excellent agreement with each other, even when anisotropic boundary energies were used. However, the simulated distributions had fewer small grains than the experimental distributions.
Origins of Cube Recrystallization Textures in Heavily Rolled High Purity Al
Authors: Inagaki Hirosuke , Umezawa Atsushi
Published: March 2009

In high purity (4N) Al containing 50 ppm Cu, very strong cube textures can be developed by cold rolling 98 % and annealing at 500 °C. The orientation density in this material amounted to as much as 220 times random, i. e. about 3 times stronger than that observed in standard 4N Al. It is expected that the origins of cube textures should be most unambiguously clarified by using this material. Commercial hot bands of this materials were cold rolled 98 % to the thickness of 132 μm and isothermally annealed at 230 °C. Detailed EBSP analyses were made both on the rolling plane and on the longitudinal section at each stage of annealing. It was found that in the hot band of this high purity Al, cube orientations were mostly rotated away into other orientations due to low temperature hot rolling with high rolling reductions. Therefore, regions having cube orientations were very few. They were not present in the form of so called cube bands, which had been reported in previous investigations, but in the form of isolated, rather equi-axed recrystallized grains. After 98 % cold rolling, these remaining cube regions were fragmented, and further rotated away into other orientations, so that only very few cube oriented regions were observed in the cold rolled materials. However, it was from such deformed cube oriented regions that the most potential exact cube recrystallized grains were formed. They were nucleated much earlier and grew much faster than grains of other orientations.
Recrystallization in an IF-Ti Steel after Low Deformation Amount by Tensile Strain
Authors: Samet-Meziou Amel , Etter Anne Laure , Baudin Thierry , Penelle Richard
Published: March 2009

The first steps of recovery and recrystallization in an IF-Ti steel after 35% deformation by uniaxial tension have been studied by Electron Back Scattered Diffraction (EBSD), Orientation Imaging Microscopy(™) (OIM) and Transmission Electron Microscopy (TEM). Two types of substructure are created after tensile strain: diamond shaped cells for the {111}<110> component and equiaxed cells for {001}<110> component. The recovery is by the decrease of dislocation density inside cells, the refinement of the cell walls, the vanishing of the cell wall, the cell coalescence and the cell growth. Recrystallized grains developed by two main recrystallization mechanisms: the “generalized recovery” and the “bulging”. Both mechanisms are based on continuous growth of subgrains followed or not by the migration of the prior grain boundaries.
Microstructure and Texture in Free-Standing CVD Diamond Films
Authors: Feng H.P. , Zhu H.X. , Mao Wei Min , Chen Leng , Lu Fan Xiu
Published: March 2009

Free-standing CVD diamond films were prepared under the substrate temperature in the range of 850-1050oC. Macro- and micro-textures of the films were investigated based on the SEM observation as well as on the ODF and EBSD analysis. It was found that certain growth selection process appeared during diamond deposition which, however, did not lead to a strong film texture. It is indicated that strong fluctuation of growth ratio V<100>/V<111> and frequent growth twinning during film deposition resulted in randomization effect of grain orientations, which can be transformed by adjusting the parameters of film preparation.
Texture Investigation in Cu Damascene Interconnects during Annealing
Authors: Cho Jae Young , Lee Hyo Jong , Kim Hyoung Bae , Szpunar Jerzy A.
Published: March 2009

Textural changes of Cu interconnects having a different line width were investigated after annealing. Texture was measured by XRD (x-ray diffraction) at different depth of the interconnect line and on the surface of interconnects using EBSD (electron backscattered diffraction) techniques. To analyze the relationship between the stress distribution and textural evolution observed in the different samples, the stresses were calculated for the different line width at 200°C using FEM (finite element modeling) along the width and depth of the line. In this investigation, it was found that the inhomogeneity of stress distribution in Cu interconnects is an important factor necessary for understanding textural transformation during annealing. Textural evolution in damascene interconnects lines during annealing is discussed, based on the state of stress in Cu electrodeposits.
Thermomechanical Properties of Nickel Silicide: Dependence on the Microstructure
Authors: Torregiani C. , D'Haen Jan , Opsomer K. , Van Dal M.J. , van Houtte Paul , Maex Karen
Published: March 2009

Nickel monosilicide (NiSi) is a key material in microelectronics and its thermomechanical properties play an important role in determining the stress/strain field generated in a transistor structure. The Coefficient of Thermal Expansion (CTE) is of particular importance in the determination of such a field. As NiSi is used in microelectronics in its polycrystalline form, it becomes of particular interest to study the thermomechanical behaviour of the NiSi aggregate, considered as a unique macroscopic body. The grain orientation of a 120 nm polycrystalline NiSi film grown on single crystal silicon has been studied by means of electron diffraction, and the evaluation of the CTE tensor of the film in the wafer reference frame has been performed by weighted averaging the single grain contributions. The results clearly show the importance of orientation distribution in determining the value of the equivalent coefficient of thermal expansion of the aggregate.
Cube Texture Formation in P/M Ni, Ni-W and Ni-Mo Alloy Tapes for Coated Superconductor Applications
Authors: Bhattacharjee P.P. , Ray R.K. , Upadhyaya A.
Published: March 2009

Pure Ni, Ni-5at.%Mo and Ni-5at.%W prepared through P/M route have been severely cold deformed (~95%) and given different heat treatments to develop sharp cube component ({001}<100>) for coated superconductor applications. It was found that amongst the three materials studied, Ni-5at%W develops the most sharp cube texture. This is in contrary to the observation in similar materials produced by the melting and casting route.
Strain Dependence of Magnetic Anisotropy in Low-Carbon Production Steels
Authors: van den Berg F.D. , Ploegaert H.T.
Published: March 2009

The magnetic parameters of steel depend on the mutual orientation of the applied magnetic field, the (applied) stress and the crystalline structure. The magnetic anisotropy can be modeled in terms of the magneto-elastic and magneto-crystalline energy distributions. By investigation of the magnetic anisotropic behaviour of steels with respect to stress, a rapid, nondestructive and possibly non-contact measurement of the residual stress can be devised that can find application in manufacturing, machining, forming and life-time assessment of steel and steel components. Reliability, robustness and versatility will constitute the main challenges to further develop these techniques for common industrial applications.
Simulation of the Lattice Strains Developed during a Tensile Test on a Multiphase Steel
Authors: Delannay Laurent , Melchior M. , Jacques Pascal J. , van Houtte Paul
Published: March 2009

This work investigates the micro-mechanics of a multiphase steel sheet during a uniaxial tensile test. Based on crystal plasticity theory, one assesses how the distribution of strain and stress is influenced by the presence of a soft b.c.c. phase and a strong f.c.c. phase. The two phases have been characterized by neutron diffraction. Initial textures are used as input in crystal plasticity simulations. Lattice strains measured in the tensile direction serve to fit hardening parameters. Three modeling hypotheses are tested: the Taylor model assumes uniform strain, the ALAMEL model considers the interaction of pairs of adjacent grains, and a finite element mesh is used to distribute strain and stress over the complete aggregate. The accuracy of each modeling is evaluated based on experimental measurements of the macroscopic stress, the heterogeneity of plastic strain, and the texture development in the two phases.
Microstructure Sensitive Design with First Order Homogenization Theories and Finite Element Codes
Authors: Kalidindi Surya R. , Houskamp J. , Proust G. , Duvvuru H.
Published: March 2009

A mathematical framework called Microstructure Sensitive Design (MSD) has been developed recently to solve inverse problems of materials design, where the goal is to identify the class of microstructures that are predicted to satisfy a set of designer specified objectives and constraints [1]. This paper demonstrates the application of the MSD framework to a specific case study involving mechanical design. Processing solutions to obtain one of the elements of the desired class of textures are also explored within the same framework.
Texture, Microstructure and Second-Phase Particles in a Ti+P Interstitial Free (IF) Steel
Authors: Jiang Q.W. , Zhao E.B. , Zhang J.G. , Chen Y. , Wang Gang , Zhang X.G. , Zuo Liang
Published: March 2009

The microstructure of Ti+P IF steel were studied after warm rolling, cold rolling and
recrystallization using X-Ray, TEM and SEM. The results show that the characteristics of warm rolled sheet are the same as that of the cold rolled, but the texture displays different characteristics in the subsequent cold rolling and recrystallization because of the numerous second-phase particles. In this work, a Ti+P IF steel sheet with high strength and plastic strain ratio was obtained.
Effect of Magnetic Annealing on Recrystallization Texture in Silicon Steel Thin Strip
Authors: Sha Y.H. , Zhou S.C. , Zou Z.K. , Zhao X. , Zuo Liang
Published: March 2009

Fe-3.10%Si thin strips were prepared by symmetric and asymmetric cold rolling from commercial grain oriented silicon steel sheets, then annealed with and without a magnetic field. Magnetic field of 12T was applied along the rolling direction. Magnetic annealing does not essentially change the texture development that recrystallization texture consists mainly of η fiber (RD//<001>), and the strongest component tends to transform from Goss ({110}<001>) to {210}<001> with the increase in speed ratio and annealing temperature. But magnetic annealing promotes Goss component in the strips rolled with small speed ratios, while decreases {210 <001> component in those rolled with large speed ratios. Possible effect mechanism of magnetic annealing was discussed.
Rolling and Recrystallization Textures in High Purity Al Cold Rolled to Very High Rolling Reductions
Authors: Todayama Atsushi , Inagaki Hirosuke
Published: March 2009

On the basis of Taylor-Bishop-Hill’s theory, many previous theoretical investigations have predicted that, at high rolling reductions, most of orientations should rotate along theβfiber from {110}<112> to {123}<634> and finally into the {112}<111> stable end orientations. Although some exceptions exist, experimental observations have shown, on the other hand, that the maximum on the β fiber is located still at about {123}<634> even after 97 % cold rolling. In the present paper, high purity Al containing 50 ppm Cu was cold rolled up to 99.4 % reduction in thickness and examined whether {112}<111> stable end orientation could be achieved experimentally. It was found that, with increasing rolling reduction above 98 %, {110}<112> decreased, while orientations in the range between {123}<634> and {112}<111> increased, suggesting that crystal rotation along the βfiber from {110}<112> toward {123}<634> and {112}<111> in fact took place. At higher rolling reductions, however, further rotation of this peak toward {112}<111> was extremely sluggish, and even at the highest rolling reduction, it could not arrive at {112}<111>. Such discrepancies between theoretical predictions and experimental observations should be ascribed to the development of dislocation substructures, which were formed by concurrent work hardening and dynamic recovery. Since such development of dislocation substructures are not taken into account in Taylor-Bishop-Hill’s theory, it seems that they can not correctly predict the development of rolling textures at very high rolling reductions, i. e. stable end orientations. On annealing specimens rolled above 98 % reduction in thickness, cube textures were very weak, suggesting that cube bands were almost completely rotated into other orientations during cold rolling. {325}<496>, which lay at an intermediate position between {123}<634> and {112}<111> along theβfiber, developed strongly in the recrystallization textures.
Texture, Tensile Properties and Press Formability of Mg-3Al-1Zn/Ti Clad Sheets Produced by Roll-Bonding
Authors: Inoue Hirofumi , Ishio Masaaki , Takasugi Takayuki
Published: March 2009

In order to improve corrosion resistance and mechanical properties of magnesium alloys, titanium with high specific strength was warm roll-bonded on the surface of AZ31 magnesium alloy sheets. Although the AZ31 alloy before roll-bonding had a typical basal texture, the AZ31 layer that constitutes a larger part of the clad sheet clearly showed off-basal texture with c-axis inclined by about 10º from the normal direction toward the rolling direction. This texture significantly affected tensile properties of clad sheets, resulting in lower proof stress and higher elongation at the rolling direction than at the transverse direction. In deep drawing tests, the 2-layered clad sheet with an outer titanium layer could be successfully formed at temperatures considerably lower than the limiting forming temperature of an original AZ31 single sheet. This is probably due to an effect of the outer titanium layer bearing tensile stress at a shoulder part of cup and an additional effect of improved deformability by off-basal texture in the AZ31 layer.
The Martensitic Transformation Texture in Ti-6Al-4V
Authors: Stanford Nicole , Bate Pete S.
Published: March 2009

The transformation texture associated with martensite formation in the titanium alloy Ti- 6Al-4V has been investigated. Samples were heated into the fully b phase and quenched to form a microstructure of very fine a' martensite with no evidence of diffusional transformation at the prior b grain boundaries. EBSD texture measurements on the martensite showed that within each prior b grain, although typically all 12 variants of a’ were formed, the fractions of variants was far from
uniform. The a’ texture was markedly different from values calculated using equal variant probability, also indicating that significant variant selection was occurring during martensitic transformation. This effect was modelled on the basis of elastic interaction between martensite events.
Influence of Deformation Substructures on the Early Mechanisms of Recrystallization in Cold-Rolled Titanium and Zirconium
Authors: Dewobroto N. , Bozzolo Nathalie , Wagner Francis
Published: March 2009

The mechanisms governing the very first stage of static recrystallization in two hexagonal alloys (commercially pure titanium and low alloyed zirconium) are investigated in this paper. Initially fully recrystallized and equiaxed materials were cold-rolled to 80% thickness reduction and subsequently recrystallized at 500°C for short times. High resolution EBSD maps were acquired in a FEG-SEM before and after annealing in order to see where and how the new grains appear. Nonoriented nucleation mechanisms are involved in both materials, and there is a strong correlation between the local deformation substructures and the recrystallization kinetics. Recrystallization is extremely fast in the areas where the deformation cells are small and highly misoriented, i.e. in the areas which underwent severe grain fragmentation. Twinning plays an important role for that purpose in the studied titanium sheet.
Anisotropy in Cold Rolling of Single Crystalline Ni3-Al-Base Intermetallic Alloys
Authors: Kishida Kyosuke , Demura Masahiko , Hirano Toshiyuki
Published: March 2009

Texture and microstructure evolution during cold rolling of binary Ni3Al single crystals were studied as a function of the initial crystal orientations. Cold rolling behavior of the single crystals is strongly dependent on the initial crystal orientations, especially on the initial rolling direction (RD). Macroscopic texture evolutions for binary Ni3Al single crystals with the initial RD close to <001> are characterized as development of dual {110}<¯112> texture above 90% cold reduction and the banded structure formation. Microstructure observations reveal the extensive formation and accumulation of the planar defects including the stacking faults and the planes where the localized shear deformations occurs, which must be responsible for the observed anisotropic cold rolling behavior of Ni3Al single crystals.
Texture Evolution during ECAP and Subsequent Annealing of an AlMg1Mn0.14 Alloy
Authors: Molodova Xenia , Gottstein Günter
Published: March 2009

The texture evolution during Equal-Channel Angular Pressing (ECAP) of an AlMg1Mn0.14 alloy was investigated. The material was subjected up to eight passes with a 90° die angle using route A. This resulted in an equivalent strain of 9.2. The obtained ECAP textures were compared to conventional simple shear textures. In order to investigate the thermal stability of severely deformed material the samples were annealed at several temperatures. The texture evolution during heat treatments was analysed.
Effect of Thermomechanical Treatment on the Texture Evolution and Superplasticity of a Zn-0.3wt.% Al Alloy
Authors: Ha Tae Kwon , Jeong Hyo Tae , Chang Young Won
Published: March 2009

Texture evolution and superplastic deformation behavior of a quasi-single phase
Zn-0.3wt%Al have been investigated. It was attempted to produce a stable and fine-grained microstructure in a dilute Zn-Al alloy through a proper thermomechanical treatment process (TMTP). The grain size of about 1 µm was obtained in the Zn-0.3 wt.% Al alloy and a relatively coarse grain size of 10 µm was also obtained through a subsequent aging treatment. The fine-grained material showed typical rolling texture with basal poles tilted about 30 degrees away from the ND toward RD,
while the coarse-grained material showed a typical recrystallization texture with basal poles parallel to ND. A series of load relaxation and tensile tests were conducted at room temperature. According to the internal variable theory of structural superplasticity, the grain boundary characters of fine and coarse-grained materials were different from each other. A large elongation of about 1400% was
obtained in fine-grained material at room temperature.
Microstructure and Magnetic Properties of Fe-6.5wt%Si Alloy Obtained by Spray Forming Process
Authors: da Silva Mário Cézar Alves , Bolfarini Claudemiro , Kiminami Claudio Shyinti
Published: March 2009

Deposits of the Fe-6.5wt%Si alloy produced by spray forming were annealed at temperatures between 900 and 1300oC, during 1h in vacuum and quenched in oil at
temperatures between 300 and 700oC, separately. Magnetic properties, singular
microstructure and random crystallographic texture were measured. After annealing at 1250°C for 1h under vacuum, the average grain size is of 500 μm, the grain orientation is random and the magnetic properties were: power loss of 1.30 W/kg, maximum permeability of 15400 and coercive force of 40 A/m, at B=1 T, f=60 Hz by using 0.60 mm thick rings for all studied samples. Higher annealing temperatures cause no decreasing of these properties. After quenched at 700°C, an improvement the magnetic properties where detected due to antiphase domain B2 growth. The magnetic properties were: power loss of 1.59 W/kg, maximum permeability of 12300 and coercive force of 76 A/m, at B=1 T, f=60 Hz.
The Influence of Pr Concentration on the Magnetic Properties of Pr-Fe-Co-B-Nb HDDR Magnets
Authors: Barbosa Luzinete Pereira , Ferreira N.A. , Takiishi Hidetoshi , de Faria Jr. Rubens Nunes
Published: March 2009

Permanent magnets were produced from annealed alloys using the hydrogenation, disproportionation, desorption and recombination (HDDR) process. The influence of Pr concentration on the magnetic properties of these magnets was studied. Under the present processing conditions Pr has a significant influence on the magnetic behaviour of these magnetic materials. Microstructural examinations revealed that free iron was completed eliminated from all studied alloys with annealing and the grain size changed somewhat with praseodymium content. It has also been shown that to obtain bonded magnets with optimum magnetic properties the praseodymium content in these alloys should be around 13.5 at%.
Densification Study of Titanium Powder Compacts
Authors: Ueta Márcia Christina Carneiro , Fracote Carlos Augusto , Henriques Vinicius André Rodrigues , de Alencastro Graça Mario Lima , Cairo Carlos Alberto Alves
Published: March 2009

Powder compaction characteristics is a very important parameter to control in order to obtain products with best mechanical properties made by P/M techniques. This work presents a study on the densification of titanium powders trying to optimize the particle size distribution for the best packing and the maximum densification by pressure compaction.
The powders used were made from titanium sponge obtained by the Kroll process. The powders were embrittled by mean of the Hydride-Dehydride process (HDH) and milled in a rotative ball-mill under vacuum. Powders with different particles sizes distributions were mixed in several proportions according to Alfred's and Andreasen’s Theory. The samples were compacted by uniaxial and isostatic pressing and sintered under vacuum. The evaluation of the densification was made following the Standard method of test for density of glass by Buoyancy (ASTM – C693-74) and by scanning electron microscopy (SEM). The samples made with powder milled during 36 hours and 12 hours presented better densification than the ones milled during shorter time and the ones with distributions combinations.
The Role of the Apparent Density on the Permeability of Porous Stainless Steel Parts
Authors: Rodrigues Daniel , Tosetti João Pedro , Beneduce Flávio , Salgado Lucio , Ambrozio Filho Francisco
Published: March 2009

Austenitic stainless steel filters are mostly used when there is an aggressive environment condition, especially when good corrosion and mechanical resistance at relatively high temperature are required. These filters are usually obtained from non-spherical, mostly atomized powders by cold pressing and sintering.
In order to achieve an adequate performance concerning permeability, powders with a narrow range of particle size should be used. However, besides particle size distribution, apparent density of the selected powder, which can be adjusted by the particle size, shape and distribution, affects the performance of the final product. Particle size distribution, particle shape and particle surface roughness control apparent density. This work presents some results on the evaluation of such effect.
Pressure Assisted WC-15%wt Co Sintering
Authors: Rodrigues M.F. , Bobrovinitchii Guerold Sergueevitch , Ramalho Alan Monteiro , Filgueira Marcello
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.
Microstructure and Some Microwave Properties of Ba2Ti9O20 Doped with ZrO2
Authors: Koldayeva Yu. , Nono Maria do Carmo de Andrade , Castro Pedro José , Fonseca S.T.
Published: March 2009

The effects of different concentrations of ZrO2 on the microstructure and dielectric properties of barium nanotitanate (Ba2Ti9O20) dielectric resonators (DRs) for microwave applications are reported. High dielectric constant, small dielectric loss as well as frequency high stability are very important for use in microwave telecommunication, particularly, in a local oscillator of an INPE Communication Satellite. Three different samples of Ba2Ti9O20 with different percentages of ZrO2 were prepared: with 2.0, 2.46 and 3.0 mol% dopant content. The dielectric constant and unloaded quality factor were determined for each different sample.
Fracture Toughness of SiC-Cu Based Alloys Cermets
Authors: Ordoñez S. , Carvajal L. , Martínez Verónica , Agurto C. , Marín J. , Olivares L. , Iturriza I.
Published: March 2009

Ceramic materials exhibit very low fracture toughness, which limits their applications. Recently, metal-ceramic composites have been developed to achieve improvements in toughness. In this work, the fracture toughness of SiC-Cu based alloys cermets, obtained by reactive infiltration, was measured at room temperature using the single edge notched beam (SENB) method. Values up to 11 MPam1/2 were obtained; these values were compared with the fracture toughness of commercial materials. The results of fracture toughness were directly related with the amount of the infiltrated metallic phase. The fracture energy was calculated using values of KIC and Young Modulus obtained from four points bending tests. Differences on toughness values were related with porosity and type of fracture of the several systems. The microstructural analysis of the fracture surfaces was carried out by scanning electron microscopy. The role of different operating toughening mechanisms; such as crack deflection, bridging, branching, and energy dissipation through microcracking and/or microplasticity; has been examined.
The Changes on Microstructure and Electrical Properties of Bi:2223/Ag Composite as a Function of the Granulation and the Content of the Added Silver Powder
Authors: dos Santos Dayse Iara , Zanata L.A.G. , Saeki M.J. , Nunes Claudia C.
Published: March 2009

The Bi-Sr-Ca-Cu-O system has been one of the most studied superconducting ceramic materials for industry applications. The most of the studies with this aim are on silver/ceramic composites, due to the benefits and great compatibility of this metal with the oxide. In this paper we describe a systematic and comparative study on Ag/BSCCO composite, made by the citrate route, in which the ceramic pellets are sintered in the presence of silver powder using several proportions and having several granulations. It was observed that the introduction of fine (0.5 and 2 μm) silver powder in the proportions of 5 wt. % always implies in a better critical current density compared to the no silver pellet. According to the results, the silver powder in excess of 5 wt.% may not promote best electrical properties, depending on the size of the silver particles.