bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure and Electrochemical Properties of FeSx Nanoparticles Synthesized by Chemical Vapor Condensation Process
Authors: Ha Jong Keun , Cho Kwon Koo , Kim Ki Won , Kim Jong Uk , Kim Yoo Young
Published: March 2009

FeSx nanoparticles were synthesized by the chemical vapor condensation (CVC) process using the pyrolysis of iron pentacarbonyl (Fe(CO)5) and sulfur (S). The influence of CVC parameter on the formation of nanoparticle and size distribution was studied. The synthesized nanoparticles consisting of FeS, FeS2 and Fe2O3 were nearly spherical shape and 5~40 nm in mean diameter.
Obtained particles were studied by applying the field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) methods. Electrochemical properties of the electrode fabricated with synthesized nanoparticles were evaluated.
Effect of Porosity on Fatigue Strength of Lotus-Type Porous Copper
Authors: Seki Hironori , Yamazaki S. , Otsuka M. , Tane Masakazu , Hyun Soong Keun , Nakajima Hideo
Published: March 2009

Tension and compression fatigue property was investigated for lotus-type porous copper possessing cylindrical pores aligned in one direction. The cyclic stress was applied in the direction parallel and perpendicular to the longitudinal axis of the pores. It was found that the fatigue strength at finite life of lotus-type porous copper is lower than that of nonporous copper, and the strength in the direction parallel to the longitudinal axis of the pores is higher than that in the perpendicular direction.
Microstructure, Mechanical Property and Antibacterial Characteristics of Ferritic Stainless Steel
Authors: Yang Jun , Zou De Ning , Li Xiao Ming , Zhu Jun
Published: March 2009

Based on the mechanism of high antibacterial performance of copper, an antibacterial
stainless steel bearing1.5wt% copper was fabricated. Processing of vacuum arc melting, hot rolling, and a series of heat treatments were applied to prepare the specimens. The relationships among the microstructure, mechanical properties, and the regime of treatment were investigated. Furthermore, the antibacterial properties of the specimens were assessed. The results showed that fine and
uniformed dispersion Cu-rich phase precipitated and accumulated along the grain boundaries of the matrix during the processing of aging, and a marked variation in tensile strength and yield strength was evaluated. In addition, antibacterial result showed that the as-received material has the ability to kill Staphylococcus and coliform bacteria in the excess of 99.99%, respectively.
Study on the Properties of Microwave Absorption of Zinc Oxide Whisker
Authors: Chu Long Sheng , Zhou Zuo Wan , Zhao Yong
Published: March 2009

In this paper, the microwave absorption behaviors of zinc oxide whisker were studied. The morphological structure of zinc oxide whisker was observed through scanning electron microscope. The effect of the structure of zinc oxide whisker on the microwave absorption, such as length-diameter ratio, cross-section appearance, and doping was analyzed. The result shows that the more irregular the cross section of the needle of zinc oxide whisker is, the more prominent the
microwave absorption appears. The less the length-diameter ratio of the needle of zinc oxide whisker is, the more obvious the microwave absorption of zinc oxide whisker becomes. The zinc oxide whisker, which had inlet ion, such as Al3+, Fe3+ , etc., in its crystal lattice has a better microwave absorption efficiency than the pure zinc oxide whisker. The further analysis found that electric conductive network can be formed easily because of the zinc oxide whisker, and the coating
had the porous structure. When microwave reaches the coating of zinc oxide whisker, the polarization of zinc oxide whisker was resulted and the electromagnetic energy lost. Firstly, electric current was transmitted through the electric conductive network and the energy transformed to heat. Secondly, tips’ phenomenon has been observed, which lead to the energy lost. Finally, the microwave energy was lost because of the tunnel effect, which will bring about leakage current.
Based on the three reasons above, microwave energy was absorbed by the coating containing the zinc oxide whisker.
Preparation of Single-Phase Aragonite Precipitated Calcium Carbonate Used as an Inorganic Eco-Material
Authors: Ahn Ji Whan , Park Hyun Seo , Kim Jeong Hwan , Cheong Sun Hee , Kim Jeong Ah
Published: March 2009

In this study, single phase aragonite PCC was synthesized by the solution process using Ca(OH)2 slurry and Na2CO3 solution as the main reactants. To begin with, the formation behavior of PCC polymorphs following changes in supersaturation was investigated, and the optimum synthetic condition of single-phase aragonite PCC was clarified after the role of NaOH in the reaction system was reviewed. In the results, it was considered that lower supersaturation was necessary to obtain a single phase aragonite; and, since the solubility of Ca(OH)2 was decreased
with the addition of NaOH by a common ion effect, it is possible to perform a experiment at a lower Ca2+ concentration. In conclusion, in the case of the reaction of the 2.5M NaOH solution, single phase aragonite was obtained. Furthermore, NaOH solution was produced as a by-product in the solution process by reacting Ca(OH)2 slurry with Na2CO3. Thus, recycling of the NaOH solution
was attempted in order to clear the environmental issue. It is difficult to recycle directly since the NaOH solution was diluted during the experiment. The optimum condition was investigated by control of experimental factors such as the concentration of Ca(OH)2, Na2CO3 and NaOH, and the
reaction temperature, after which the NaOH solution was recycled without re-treatment. The formation characteristics of aragonite PCC, such as formation yield, particle morphology and aspect ratio, were investigated.
Hydraulic Properties of Tetracalcium Aluminoferrite with Adsorption of Silicate Ions
Authors: You Kwang Suk , Ahn Ji Whan , Lee Bong Han , Han Choon
Published: March 2009

The results obtained in this study confirm that the hydration of C4AF (C: CaO, A: Al2O3, F: F2O3) is retarded by the presence of silicate ions in the solution. In practical terms, C4AF has a low hydraulic reactivity in solution containing silicate ions. The silicate ions in the solution are adsorbed on the surface of the C4AF particles, and they form a silica layer on the surface. From the results of the calculation with the DX-Xα method, it is also believed that silicate ions adsorbed on
the surface are very stable, and that there are strong interactions between silicate ions and the surface of C4AF.
Anodic Porous Zirconium Oxide Prepared in Sulfuric Acid Electrolytes
Authors: Tsuchiya Hiroaki , Macak Jan M. , Sieber Irina , Schmuki Patrik
Published: March 2009

We report the formation of self-organized porous ZrO2 layers by anodization of Zr in
H2SO4 electrolytes. Anodization at 20 V after a potential sweep from open-circuit potential with a defined sweep rate results in tube-like porous ZrO2. In particular, under optimized electrolyte condition and polarization, a highly ordered porous structure is obtained. Furthermore, sponge-like porous ZrO2 is also fabricated under a specific electrochemical condition.
Recent Development of New Alloys for Biomedical Use
Authors: Hanawa Takao
Published: March 2009

Metallic materials are widely used in medicine not only for orthopedic implants but also for cardiovascular devices and other purposes. New alloys for biomedical use are developed all over the world continuously to decrease corrosion, toxicity and fracture during implantation and increase interfacial and dynamical tissue compatibility. Most of efforts are made to develop titanium alloys,
especially in β-type alloys whose Young’s modulus is as low as cortical bone. Nickel-free alloy is also necessary to prevent nickel allergy: nickel-free austenitic stainless steels and shape memory alloys are developed. To increase iocompatibility, the controls of surface morphology and surface treatment or modification are necessary.
Design of Lubricants Using Waste Slag in Large Strain Addition Strip Processing for Ultrafine-Grained Steels
Authors: Nakamoto Masashi , Lee Joon Ho , Tanaka Toshihiro
Published: March 2009

Aiming to design new lubricants in the large strain addition strip process for
ultrafine-grained steels, we tested the possibility of using waste slag, which is generated largely from iron and steelmaking processes, municipal waste treatments and so on. We then focused our attention on the slag containing water as the new lubricant. Slag satisfies the requirement of biting the workpiece stably, which cannot be achieved with conventional lubricants, because slag is stable as a solid phase of high hardness at the biting temperature in the strip process (100~200oC). In
addition, slag contains water under hydrothermal conditions to provide lubricating effects by lowering glass transition temperature. In the present study, the effect of additive components (Al2O3, B2O3, CaO, MgO, K2O, Li2O and V2O5) on the glass transition temperature of a SiO2-Na2O-based slag containing water was examined. The glass transition temperature of the slag containing water is 150~300 oC, which is lower than that of original slag. It was also found that the glass transition temperature depends on the additive components to the slag.
Microstructural Evolution in 36%Ni Austenitic Steel during the ARB Process
Authors: Li Bo Long , Tsuji Nobuhiro , Minamino Yoritoshi
Published: March 2009

A 36mass% Ni austenitic steel was deformed to equivalent strains of 0.8 to 4.8 by the
accumulative roll-bonding (ARB) process at 500°C, with slight lubrication. We analyzed the microstructure and crystallographic analysis by employing the electron back-scatter pattern (EBSP) technique in a field emission gun (FEG) SEM. After several ARB cycles, ultrafine lamellar boundary structures elongated in the rolling direction (RD) formed uniformly in the material. Observations
indicated that the mean spacing of high-angle lamellar boundaries determined from the EBSP results decreased exponentially as a function of equivalent strain. The fraction of high-angle boundaries (HABs) increased, thus the average misorientation of the boundaries increased with increasing strain. In the six-cycle ARB-processed specimen, the mean spacing of the uniform lamellar boundaries was
150 nm, the fraction of HABs was 75%, and the average misorientation was 32°. The ultrafine lamellar boundary structure in the 36%Ni austenitic steel was finer and straighter than in ferritic steel (IF steel) deformed under similar conditions, probably because recovery occurs more easily in ferritic steel than austenitic steel.
Liquid Crystalline Behaviour of Chitosan in Formic, Acetic, Monochloroacetic Acid Solutions
Authors: Prabaharan Mani , Borges João Paulo , Godinho M.H. , Mano João F.
Published: March 2009

The objective of this work was to prepare polysaccharide-based gels exhibiting liquid
crystalline properties. Such systems may be used in some optical or in biomedical applications, where biodegradability is required. Chitosan is a derivative of chitin, widely used in a series of medical applications. Due to its rigid structure, chitosan or its derivatives may show lyotropic mesophases in certain conditions. In this work, chitosan solutions were prepared by mixing completely the polysaccharide with different concentration of formic, acetic and monochloroacetic acids at room temperature. X-ray diffraction patterns of the gels did not show the existence of a
crystalline structure. Finger-prints texture observed by polarised optical microscopy was attributed to a cholesteric liquid crystalline phase that usually develops in concentrated solutions. Values of the nematic chiral pitch (P) were determined in function of acid solution concentration. The critical concentrations (C*) to form a lyotropic liquid crystalline phase in formic, acetic and monochloroacetic acids were determined, and the obtained values were confronted with the expected critical concentration based on the Flory formalism. The critical concentration values were
found to be dependent upon the acid used.
Problems of Heat Source Modeling in Iso–Exothermic Materials Used as Riser Sleeves in Foundry
Authors: Ignaszak Zenon , Popielarski Paweł
Published: March 2009

The modeling of heat transfer in materials containing exothermic components must take
into consideration the presence of heat sources in the Fourier–Kirchhoff equation. The aim of this
investigation was the identification of real and effective thermophysical parameters of the
insulating–exothermic materials used as riser sleeves containing these exothermic heat sources. The
experiments of steel pouring into the mould, containing different insulating and exothermic sleeves
were carried out, using thermocouples measurement systems (thermal analysis of casting–mould
system). Then the thermophysical coefficients of these materials were calculated using inverse
problem solution. The worked time–dependent formula of exothermic reaction heat (heating yield
in W/m3) was called heat source function. The paper presents the basis and the practical expression
of heat source by different functions, its justification and the results of simulations using these
functions. The numerical system Calcosoft and its Inverse Solution procedure were applied.
Sub-Surface Defects Induced by Low Energy Ar+ Sputtering of Silver
Authors: Duarte Naia Marco , Gordo Paulo M. , Teodoro Orlando M.N.D. , de Lima Adriano P. , Moutinho Augusto M.C. , Brusa Roberto S.
Published: March 2009

Induced defects in silver polycrystalline samples irradiated with 4 keV Ar+ were characterised with slow positron implantation spectroscopy. The implanted gas was found to interact with ion irradiation defects. The evolution of the defects and gas-defect interactions were followed through a multi-step isochronal annealing treatment. Two different defected regions were detected. A region near to the surface, due to a distribution of vacancy-like defects produced by irradiation, and a deeper one due to coalescence of Ar. The deeper defects evolve with thermal treatments and probably produce cavities which are not easily recovered.
Structural Characterization of Lead Metaniobate Thin Films Deposited by Pulsed Laser Ablation
Authors: Cardoso Fátima , Almeida Bernardo G. , Caldelas Pedro , Mendes Jorge A.
Published: March 2009

The ferroelectric polymorph of lead metaniobate (PbNb2O6) presents an orthorhombic structure that is metastable at room temperature. This phase is obtained by quenching from high temperature. The fabrication of lead niobate thin films with this orthorhombic form has been reported to be difficult due to the presence of phases with the rhombohedric form or other nonstoichiometric
phases. In this work, lead niobate thin films have been prepared by laser ablation, at
different oxygen pressures and with different substrate temperatures. Their structure was studied by X-ray diffraction and their surface was examined by scanning electron microscopy (SEM). The results show that for low deposition temperatures the films presented a rhombohedric-PbNb2O6 structural phase. As Tdep increases the films started to develop an orthorhombic- PbNb2O6 structure
that appeared at 400°C and remains up to 600°C. For lower oxygen pressure during deposition, a mixture of this phase and other orthorhombic lead deficient phases are present in the films. On the other hand, by increasing the oxygen pressure the lead deficient phases are strongly reduced and the films present only the orthorhombic- PbNb2O6 structure.
Characterization of Powder Metallurgy (PM) Nickel Base Superalloys for Aeronautical Applications
Authors: Silva José M. , Cláudio Ricardo A. , Sousa e Brito A. , Branco Carlos M. , Byrne Jim
Published: March 2009

During the last decade, some major improvements have been achieved concerning the evaluation of new types of materials suitable for aeronautical components exposed to severe operational conditions, such as turbine disks. Due to their outstanding mechanical properties, nickel base superalloys assumed a preferential position when compared with other conventional metallic alloys, benefiting from both their superior fatigue strength and high temperature behaviour. However, these alloys evince a high sensibility concerning possible defects that can arise due to
certain types of loading, such as porosities and cavities associated with creep-fatigue at high temperatures. The present paper compiles some experimental results obtained for two types of recent nickel base superalloys. Some fatigue tests were performed using two configurations of these materials: a set of Udimet 720Li specimens (CT geometry) and a set of RR1000 specimens (CN
geometry). A maximum temperature of 650°C was considered in both types of materials. The mechanical properties of these alloys were inferred via typical FCGR parameters, such as da/dN vs K curves, complemented with detailed analyses of the cracking mechanisms based on SEM observations. Finally, some metallographic characterization tests were carried out in order to determine the average grain size of these PM alloys and to confirm the presence of important microstructural constituents that can influence the overall fatigue performance of these materials.
Nitrogen Effect in Microstructural Parameters of a Cast Duplex Stainless Steel
Authors: Santos Henrique , Leal Joana , Sá Carlos
Published: March 2009

Duplex stainless steels (d2s) are intended to present a microstructure composed of similar volume fractions of austenite and ferrite; this is the phase composition leading to the best compromise of mechanical and corrosion properties.
To stabilize the austenite phase, nitrogen is added as an alloying element in the so-called second generation d2s; nitrogen is a cheap element (compared to nickel, the most common austenite stabilizer) that simultaneously increases the strength by a solid solution hardening effect; usually nitrogen contents in the second generation d2s vary from 0.15 to 0.25 weight %. The effect of a 0.14 % nitrogen addition to a cast d2s with a nominal composition corresponding to EN 10283 has been studied to evaluate its austenite stabilizing effect and its influence on the partition intensity of the elements contributing to the pitting corrosion resistance (chromium and
molybdenum) between the two phases composing the microstructure.
Two cast d2s have been prepared for this study: one without any nitrogen addition and another with 0.14% nitrogen; both had the same nominal composition.
Specimens of the two cast d2s have been heat treated in a range of temperatures from 1050 to 1400°C, every 50°C; after a 2 hour soaking the specimens have been cooled in water. It is known that increasing the solution temperature increases the volume fraction of ferrite in the cast d2s microstructure. Both the volume fraction of each constitutional phase (austenite and ferrite) and the respective chromium and molybdenum content have been measured. The results of the volume fraction measurements showed an intense austenite stabilizing effect of the nitrogen.
The results of the microanalysis of chromium and molybdenum showed that both elements present an ability to concentrate in the ferrite, although the molybdenum partition is clearly more intense than the chromium partition.
Residual Strength after Low Velocity Impact in Carbon-Epoxy Laminates
Authors: Amaro Ana M. , Reis Paulo N.B. , de Moura Marcelo F.S.F.
Published: March 2009

The aim of present work is to study the influence of low energy impacts on residual
strength of carbon-epoxy laminates. Experimental tests were performed on [0,90,0,90]2s and [0,90]8 laminates using a drop weight-testing machine. The influence of the laminate stacking sequence is analysed under 1.5 J, 2 J, 2.5 J and 3 J impact energies, corresponding to a 0.91 ms-1, 1.05 ms-1, 1.18 ms-1 and 1.29 ms-1 of impact velocity, respectively. The impacted plates were inspected by CScan
to evaluate the size, shape and position of the delaminations through the thickness of the plate. The same plates were inspected by C-Scan before the impact, to evaluate the eventual presence of defects produced during the manufacturing process. The residual flexural strength showed that the [0,90,0,90]2s laminates have better performance than the [0,90]8 ones. The explanation is related
with the lower flexural stiffness of the antisymmetric lay-up relatively to the symmetric one.
Piezoelectric and Optical Response of Uniaxially Stretched (VDF/TrFE) (75/25) Copolymer Films
Authors: Serrado-Nunes Jivago , Kouvatov A.Z. , Müller Volkmar , Beige Horst , Brandão Pedro M. , Belsley Michael , Moreira M. Vitor , Lanceros-Méndez Senentxu
Published: March 2009

The phase diagram of the poly(vinylidene fluoride-trifluorethylene) (P(VDF-TrFE)) copolymer system shows for VDF contents of 50...85 mol% a ferroelectric (FE)-paraelectric (PE) phase transition below melting temperature. Investigations on P(VDF-TrFE) 75/25 samples revealed a slight anisotropic behaviour, which leads to a strongly anisotropic stretching effect both
on the phase transition and on the amount and nature of the FE phase in samples subjected to mechanical stretching along the main directions of the film.
In this work, both the refractive index n1,2 and the piezoelectric coefficient d33 of mechanically stretched P(VDF-TrFE) have been measured for samples with different levels of permanent deformation. These parameters are found to reflect the anisotropy of the permanently deformed samples. The stretching effect is most pronounced (n1,2) or limited (d33) to the vicinity of the yielding point of the material. Above the yielding point, almost the piezoelectric d33 coefficient of
the non-deformed sample is observed for samples with large permanent deformation.
Synthesis of Nanocrystalline CeO2 Using Mechanochemical Method: The Effect of Milling Time on the Particle Size
Authors: Hadi Abdul , Yaacob Iskandar Idris , Gaik Cheah Seok
Published: March 2009

Nanocrystalline cerium dioxide (CeO2) has been successfully synthesized by
mechanochemical technique at 12, 24, 36, 48 and 60 hours milling times. The starting materials,
hydrated cerium carbonate and sodium hydroxide, were mixed in a weight ratio of 4:1 and were
milled in a planetary ball mill with ball to powder ratio of 10:1. The high energy impact forces
provided by the milling media caused collision of starting materials and allowed the chemical
reaction to occur thus produced nanocrystalline cerium dioxide. The products were characterized
using a battery of characterization methods, including thermogravimetric analysis (TGA),
differential scanning calorimetry (DSC), X-ray diffraction (XRD), and gas adsorption-desorption
measurement. The nanocrystalline CeO2 with 6.7 nm of crystallite size and specific surface area of
66.66 m2/g was obtained when the sample was milled for 60 hrs and they annealed in air at 350
oC. The result showed that the crystallinity of nanocrystalline CeO2 decreased with increasing
milling time.
Modification of Epoxy Resin Using Liquid Natural Rubber
Authors: Zainol Ismail , Ahmad Mohamad Ibrahim , Zakaria Fadzil Ayad , Ramli Anita , Marzuki Haslan Fadli Ahmad , Aziz Azlan Abdul
Published: March 2009

The cure process and the mechanical properties of liquid polymethylmethacrylate grafted
natural rubber (LMG30) modified epoxy have been studied. Addition of LMG30 significantly
increased the fracture toughness and the impact strength of the epoxy resin. The fracture toughness
increased up to 22 fold (17.3 MNm-3/2) when modified with 5 phr LMG30. The glass transition
temperature however, decreases as the rubber content increases. The SEM analysis shows uniform
dispersion of rubber particles within the epoxy matrix with average particle size between 0.4 to 0.8
0m in diameter.
Comparative Studies on Li/LiI-Li2WO4-Li3PO4/Metal Oxide Electrochemical Cells
Authors: Ahmad Azizah Hanom , Subban Ri Hanum Yahaya , Zakaria R. , Ali A.M.M.
Published: March 2009

A series of experiment has been carried out to study the electrochemical
performances of lithium primary cells using different cathode materials. The cathode
material was made of metal oxide, electrolyte, activated carbon, and PVdF with a wt. ratio
of 60: 20:10:10. PVdF was added as a binder. The metal oxides used are MnO2 and V2O5.
The anode was made up of lithium metal and LiI-Li2WO4-Li3PO4 compound is used as an
electrolyte. In this work the open circuit voltage (OCV) of Li/MnO2 and Li/V2O5 obtained is
about 3.0 V and 3.2 V respectively. This shows that LiI-Li2WO4-Li3PO4 compound is
lithium ion conductor. Lithium cell showed better performance at 100º C than at room
temperature. Among these two types of cells investigated, cell Li/V2O5 worked better than
the Li/MnO2 cell at room temperature and at 100°C as this cell exhibits the longest
continuous discharge time and the highest OCV.
Salicylic Acid and Dibuthyl Phatalate (DBP) Interaction in PMMA-Based Gel Electrolytes
Authors: Isa M.I.N. , Arof A.K.
Published: March 2009

A gel electrolyte system was prepared by dissolving poly(methyl methacrylate) (PMMA) in ethylene carbonate (EC) and propylene carbonate (PC) doped with salicylic acid (SA) and plasticized with dibutyl phthalate (DBP). The composition of the electrolyte was 35 wt% EC-30 wt% PC-5 wt% SA-5wt% DBP-25 wt% PMMA. The presence of a hump at ~760 cm-1 and a shoulder at 1155 cm-1 in the spectrum of SA-DBP indicate the protonation of DBP. The effect of these bands can also be observed in the spectrum of the gel. Hence, SA has dissociated producing H+ which then interacts datively at the oxygen sites of DBP.
Microstructure Evolution and Dielectric Properties of Nb/Mn and Dy/Mn Doped Barium Titanate Ceramics
Authors: Živković Ljiljana , Paunović V. , Miljković M. , Ristić Momcilo M.
Published: March 2009

Nb/Mn and Dy/Mn codoped BaTiO3 specimens, prepared by conventional solid-state procedure, were investigated regarding their microstructural and dielectric properties. The powders were doped with Nb2O5 and Dy2O3 with an amount of 0.1, 0.5 and 1.0 at% of dopants ions. The MnO content of 0.05 at% Mn was the same in both types of samples. The specimens were sintered in air at 1320 and 1350 °C for two hours. Microstructural and compositional studies were done by SEM equipped with EDS. In low doped BaTiO3 the grain size is around 1-3 μm, while in ceramics with high dopant content (1.0 at%) the grain size distribution was in the range of 3-10 μm. High dielectric constant is associated with small-grained microstructure, being 5000 for Dy-doped and 6500 for Nb-doped BaTiO3 sintered at 1350 °C. The specimens with low dopant content demonstrate the Curie-Weiss behavior in a paraelectric regime. A nearly flat permittivity response with temperature was obtained for specimens with 0.5 and 1.0 at% Dy content. Loss tangents were in the range of 0.03 - 0.32.
Phase Relations in the ZrO2-Y2O3-La2O3 System at 1250 °C
Authors: Andrievskaya E.R. , Red'ko V.P.
Published: March 2009

Phase equilibria in the ternary system ZrO2-Y2O3-La2O3 at 1250 °C have been studied and isothermal section have been developed. Fine chemical technique such as co-precipitation was used to obtain ceramic nanopowders (with average particle size of 8-20 nm) available for nonisothermal sintering as well. The phase compositions of the annealed samples were studied by methods of X-ray analysis at 20 °C, petrographic and electron microprobe X-ray analyses. No ternary compounds were found. The phase equilibria in the system are determined by intermediate phases: La2Zr2O7 and LaYO3 that crystallize in the pyrochlore and perovskite-type structures, respectively. Solid solutions based on the constituent oxides such as tetragonal (T) and cubic fluorite-type structure (F) ZrO2, cubic form of rare-earth oxides (C-type) Y2O3,as well as hexagonal (A) and monoclinic (B) forms La2O3 were found at 1250 °C. The nanocrystalline powders of tetragonal zirconia actively sintered on heating up to 1150-1400 °C and the powders of lanthanum zirconate show active densification on heating up to 1550-1650 °C. The electrical properties (at 600-950 °C) of yttria-doped pyrochlore were measured, the highest conductivity has been revealed at 10 mol % Y2O3.
Spectroscopic Ellipsometry as a Tool for On-Line Monitoring and Control of Surface Treatment Processes
Authors: Eitzinger Christian , Fikar Jan , Forsich C. , Humlíček J. , Krüger Albrecht , Kullmer Roland , Laimer J. , Lingenhöle Erich , Lingenhöle Klaus , Mühlberger Michael , Müller Thomas , Störi H. , Wielsch Uwe
Published: March 2009

Modern material technology relies increasingly on processes for surface modification and coating. Generally, we are lacking a possibility to monitor the progress of such processes. Thus the outcome can only be analyzed after the end of the whole process cycle. We are proposing to use spectroscopic ellipsometry (SE) as an on-line monitoring tool. SE, as an optical method, is not affected by high temperatures, process gases, plasmas, etc. It can be used as a monitoring tool or a sensor for closed loop control of processes. The main difficulty is the on-line interpretation of SE data. Depending on the nature of the process monitored or controlled, different models are used for the interpretation. These models predict the SE response depending on different parameters describing the surface under investigation. A fitting process is used to solve the inverse problem, i.e. extracting material data from the SE spectra. We expect increased process stability and shorter development time as a practical benefit from the use of SE.
Infrared and Dielectrical Properties of SrTiO3:Nd
Authors: Spasović Slavica , Paunović N. , Popović D. , Dojčilović Jablan
Published: March 2009

Far-infrared reflection spectra and results of dielectric measurements of SrTiO3 single
crystal doped by neodymium are presented in the paper. Dielectric investigations were conducted at
temperature range from 25 K to room temperature for the test frequency 1MHz. The numerical
analysis of the far-infrared reflection spectra made using a fitting procedure based on factorized
form of the dielectric function. The results for SrTiO3: Nd are compared with those for pure
crystal. The lowest-frequency phonon mode is found to be strongly influenced by presence of
neodymium ions in SrTiO3 single crystal.
Reaction of Ce1-xRexO2-δ Nanopowders Synthesis
Authors: Bošković Snezana , Djurović D. , Matović B. , Čančarević M. , Dohčević-Mitrović Z. , Popović Zoran V. , Zinkevich Matvei , Aldinger Fritz
Published: March 2009

One of the methods for powder synthesis that is both cost and time effective is the selfpropagating
room temperature synthesis. We applied this method to synthesize rare earth doped
ceria nanopowders. Since they exhibit very high ionic conductivity at intermediate temperatures
these compositions are attractive for a new generation of nanostructured ceramics applicable in
solid oxide fuel cells as electrolytes. In this paper we paid our attention to the reaction based on
methathetical pathway, whereby solid solution nanopowders of rare earth elements with ceria were
obtained at room temperature. Compositions of Ce1-xRexO2-δ (Re = Y , Nd) were synthesized with x
ranging from 0 to 0.20. The reaction course is discussed and the properties of the obtained powders
are presented.
Fatigue Behaviour in Fine Grained Aluminium Alloys
Authors: Venning L.J. , Sinclair I. , Reed P.A.S.
Published: March 2009

The effects of alloy production method on microstructure and hence fatigue crack
growth rate and fracture mechanism have been examined for a variety of fine-grained/high
dispersoid Al-Li-Mg-Zr and Al-Li-Cu-Mg-Zr alloys. Microstructures have been assessed by
scanning and transmission electron microcopy, together with electron back scattered diffraction
pattern assessment. In these fine-grained/high dispersoid materials, high crack growth rates are
seen in comparison to the traditional DC cast alloys, excepting a material with high volume
fraction of shearable precipitate. The effects of fracture surface roughness and closure levels in
determining crack growth rates has been assessed.
Aluminium in Future Cars - A Challenge for Materials Science
Authors: von Zengen Karl Heinz
Published: March 2009

Use of aluminium in modern cars has increased during the past 50 years due to the good
properties of the metal and the need for light weighting cars. The permanent rise in energy costs
and need for reduction of emissions world wide make aluminium more and more attractive for
automotive use. Nevertheless, additional costs for light weighting must remain affordable –
materials scientists and process engineers are challenged to meet these requirements.
Accumulative Roll Bonding of AA8006, AA8011 and AA5754 Sheets
Authors: Slámová Margarita , Homola Petr , Sláma P. , Karlík Miroslav , Cieslar Miroslav , Ohara Yoshitatsu , Tsuji Nobuhiro
Published: March 2009

Accumulative Roll Bonding (ARB) is a technique of grain refinement by severe plastic
deformation, which involves multiple repetitions of surface treatment, stacking, rolling, and cutting.
The rolling with 50% reduction in thickness bonds the sheets. After several cycles, ultrafine-grained
(UFG) materials are produced. Since ARB enables the production of large amounts of UFG materials,
its adoption into industrial practice is favoured. ARB has been successfully used for preparation of
UFG sheets from different ingot cast aluminium alloys. Twin-roll casting (TRC) is a cost and energy
effective method for manufacturing aluminium sheets. Fine particles and small grain size are intrinsic
for TRC sheets making them good starting materials for ARB. The paper presents the results of
a research aimed at investigating the feasibility of ARB processing of three TRC alloys, AA8006,
AA8011 and AA5754, at ambient temperature. The microstructure and properties of the ARB were
investigated by means of light and transmission electron microscopy and hardness measurements.
AA8006 specimens were ARB processed without any problems. Sound sheets of AA8011 alloy were
also obtained even after 8 cycles of ARB. The AA5754 alloy suffered from severe edge and notch
cracking since the first cycle. The work hardening of AA8006 alloy saturated after the 3rd cycle,
whereas the hardness of AA5754 alloy increased steadily up to the 5th cycle. Monotonous increase in
strength up to 280 MPa was observed in the ARB processed AA8011 alloy.
Use of Small-Angle X-Ray Scattering for the Characterisation of Precipitates in Aluminium Alloys
Authors: Deschamps Alexis , Dumont Myriam , Lae Ludovic , Bley Françoise
Published: March 2009

This paper presents two studies illustrating the possibilities of Small-Angle X-ray
Scattering for characterising quantitatively the state of precipitation in aluminium alloys. In the first
example, maps are presented, of precipitate size and volume fraction in the cross-section of friction
stir welds of AA7449 alloy. It is shown that the influence of welding speed on the distribution of
mechanical properties can be understood using this microstructural data. In the second example, the
precipitation kinetics in an Al-Zr-Sc alloy is evaluated by in-situ small angle X-ray scattering.
Evidence is given for the heterogeneous chemical structure of the Al3(Zr,Sc) precipitates, consisting
of a Zr-rich shell surrounding a Sc-rich core. It is shown that this particular distribution results in a
very good resistance to coarsening of the precipitate microstructure.
Laser-Ultrasonic Characterization of the Microstructure of Aluminium
Authors: Moreau André
Published: March 2009

Ultrasonic velocity and attenuation measurements are powerful tools to infer much information about the microstructure and properties of aluminum and its alloys. Laser-ultrasonics is a technology that enables doing these measurements remotely, in-situ or inline and in a fraction of a second. Therefore, it is possible to characterize the thermomechanical processing of aluminum alloys with unprecedented time resolution. This paper reviews the physical principles that allow relating velocity and attenuation measurements to various materials properties and microstructural features such as elastic moduli, crystallographic distribution orientation (texture), residual stresses, recrystallization and dislocations. In-situ (in laboratory furnaces) and in-line measurement examples from the Industrial Materials Institute research group are reviewed and presented.
Guinier-Preston and Guinier-Preston-Bagaryatsky Zone Reversion in Al-Cu-Mg Alloys Studied by NMR
Authors: Bastow Timothy J. , Hill Anita J.
Published: March 2009

GP and GPB zone formation in Al-Cu-Mg alloys proceeds rapidly at room
temperature immediately subsequent to STQ. This structure evolution is well known for
GP zones but not for GPB zones. In many age-hardenable Al-Cu-Mg alloys this vacancy
assisted diffusion of Cu from solid solution to form zones is essentially complete within
50 hours with only a small residual quantity of Cu remaining in solid solution. The alloy
then remains in this metastable state. This zone formation is observed here using 63Cu
NMR for the alloys AA2014 and AA2124 which lie in the α-θ (GP) and α-S (GPB)
phase fields respectively. However these zones which form so readily at room
temperature are unstable on aging at higher temperatures. Rapid dissolution of the zones,
and their reversion back into solid solution at elevated temperatures is explicitly
demonstrated by 63Cu nuclear magnetic resonance (NMR). At this stage the Cu is shown
to remain stably in solid solution at room temperature. Further aging at the same elevated
temperature is then shown to reform the zones with further continuous evolution to either
the θ-phases (AA2014) or S-phase (AA2124).
High Strain Rate Behaviour of Aluminium Alloy Sheet
Authors: Worswick Michael J. , Smerd R. , Salisbury C.P. , Winkler S. , Lloyd David J.
Published: March 2009

This paper presents results from quasi-static and high rate tensile testing of three aluminum sheet alloys, AA5754, AA5182 and AA6111, all of which are candidates for replacing mild steel in automotive bodies. Tests were performed at quasi-static rates using an Instron apparatus and at strain rates of 600 to 1500 s-1 using a tensile split Hopkinson bar. Additionally, an in-depth investigation was performed to determine the levels of damage within the materials and its sensitivity to strain rate. The constitutive response of all of the aluminum alloys tested showed only mild strain rate sensitivity. Dramatic increases in the elongation to failure were observed with increases in strain rate as well as greater reduction in area. Additionally, the level of damage was seen to increase with strain rate.
Aging Behaviour of Aluminium Alloys after Severe Plastic Deformation
Authors: Horita Z.
Published: March 2009

The process of severe plastic deformation (SPD) makes it possible to reduce the grain
size to the submicrometer or nanometer range in many metallic materials. When the SPD process is
applied to age hardenable alloys, it may also be possible to control aging behavior. In this study, a
technique of equal-channel angular pressing (ECAP) is used as an SPD process and aging behavior
is examined on the three selected Al alloy systems such as Al-Ag, Al-Mg-Si and Al-Si-Ge. The
microstructures are observed using transmission electron microscopy and the mechanical properties
including hardness are measured. It is shown that the SPD process introduces unusual phenomena
in the precipitation process and there should be a potential for enhancement of strength over the
conventional age-hardening process or for improvement of ductility while keeping the high
strength.
The Effect of Grain Refinement and Cooling Rate on the Hot Tearing of Wrought Aluminium Alloys
Authors: Easton Mark , Grandfield John F. , StJohn David H. , Rinderer Barbara
Published: March 2009

Using modifications to the Rappaz-Drezet-Gremaud hot tearing model, and using empirical equations developed for grain size and dendrite arm spacing (DAS) on the addition of grain refiner for a range of cooling rates, the effect of grain refinement and cooling rate on hot tearing susceptibility has been analysed. It was found that grain refinement decreased the grain size and made the grain morphology more globular. Therefore refining the grain size of an equiaxed dendritic grain decreased the hot tearing susceptibility. However, when the alloy was grain refined such that globular grain morphologies where obtained, further grain refinement increased the hot tearing susceptibility. Increasing the cooling decreased the grain size and made the grain morphology more dendritic and therefore increased the likelihood of hot tearing. The effect was particularly strong for equiaxed dendritic grain morphologies; hence grain refinement is increasingly important at high cooling rates to obtain more globular grain morphologies to reduce the hot tearing susceptibility.
Vacancy-Solute Interactions in Al-Cu-Mg
Authors: Marceau R.K.W. , Ferragut Rafael , Dupasquier A. , Iglesias M.M. , Ringer Simon P.
Published: March 2009

This is an initial report of a multi-technique study on the effect of Mg alloying on solute-vacancy interactions during the early stages of ageing of dilute 2xxx Al-Cu-Mg alloys so as to better understand the early rapid hardening (RH) that occurs in certain compositions of these alloys and the more general phenomena of secondary hardening (SH) at ambient temperatures. Therefore, RH at 150 °C and SH at room temperature from the as-quenched condition and after 60 sec ageing at 150 °C were studied in Al-1.1Cu and Al-1.1Cu-0.5Mg (at. %) variously by positron annihilation lifetime spectroscopy (PALS), coincidence Doppler broadening (CDB) spectroscopy and atom probe tomography (APT) and monitored by Vickers hardness measurements. The present results indicate that Cu-Cu, Mg-Mg and Cu-Mg clusters are formed in the ternary alloy already in the asquenched state and that they persist during ageing at 150 °C. The fraction of the solutes Cu and Mg that were associated with vacancies after ageing was increased 10-fold and double, respectively and the strength of the Cu clustering is enhanced greatly after 60 sec at 150 °C.
Advanced Nanostructural Analysis of Aluminium Alloys Using Atom Probe Tomography
Authors: Ringer Simon P.
Published: March 2009

This paper sets out the needs for and recent advances in microscopy in Al alloys, using solutesolute and solute-vacancy clustering as examples. Cluster-assisted nucleation and cluster strengthening are discussed and this is followed by a discussion of the local electrode atom probe. Heuristic and algorithmic tools for assessing the nanoscale microstructure or nanostructure of Al alloys acquired from atom probe tomography experiments are then presented.
Precipitation Hardening in Al-Cu-Mg Alloys: Analysis of Precipitates, Modelling of Kinetics, Strength Predictions
Authors: Starink Marco J. , Yan J.L.
Published: March 2009

In Al-Cu-Mg with compositions in the α+S phase field, precipitation hardening is a twostage
process. Experimental evidence shows that the main precipitation sequence in alloys with Cu
contents in excess of 1wt% is involves Cu-Mg co-clusters, GPBII/S'' and S. The first stage of the
age hardening is due to the formation of Cu-Mg co-clusters, and the hardening can be modelled
well by a modulus hardening mechanism. The appearance of the orthorhombic GPBII/S'' does not
influence the hardness. The second stage of the hardening is due to the precipitation of S phase,
which strengthens the alloy predominantly through the Orowan looping mechanism. These findings
are incorporated into a multi-phase, multi mechanism model for yield strength of Al-Cu-Mg based
alloys. The model is applied to a range of alloys with Cu:Mg ratios between 0.1 and 1 and to heat
treatments ranging from room temperature ageing and artificial isothermal ageing to rapid heating
to the solution treatment temperature. The predictive capabilities of this model are reviewed and its
constitutive components are compared and contrasted with a range of other methods, such as the
Kampmann-Wagner and JMAK models for precipitation as well as the LSW model for coarsening.
Grain Boundary Precipitate Modification for Improved Intergranular Corrosion Resistance
Authors: Unocic Kinga A. , Kobe Paul , Mills Michael J. , Daehn Glenn S.
Published: March 2009

Intergranular corrosion is a significant concern for Al-Mg alloys when subjected to a
corrosive salt-water environment. To address this issue, the standard composition of a 5XXX series
aluminum alloy (AA5083) was modified in an attempt to improve the alloy’s overall corrosion
resistance through alloying and thermal processing. The concept being that through alloying and heat
treatments, desirable precipitate phases such as τ- and/or τ-copper rich phase(s) that are known to offer
corrosion resistance would potentially form that could effectively improve intergranular corrosion
behavior. Therefore, the chemical composition of standard AA5083 was modified by adding various
amounts of copper and zinc. Sensitization heat treatments were then performed to determine the
specific conditions under which these phases would form. LOM, SEM, STEM imaging and
conventional TEM were used to analyze microstructural features. Corrosion was attributed to a
network of detrimental Mg-rich grain boundary precipitates in the standard alloy. Alloying with Cu and
Zn can offer improved intergranular corrosion behavior. The mechanism seems to be either by delaying
or eliminating precipitation at the grain boundaries.
Blister Free Heat Treatment of High Pressure Die-Casting Alloys
Authors: Lumley Roger N. , O'Donnell Robert G. , Gunasegaram Dayalan R. , Givord Michel
Published: March 2009

Conventionally produced high pressure die-cast (HPDC) components are not considered to
be heat treatable because gases entrapped during the die-casting process expand during solution
treatment causing unacceptable surface blistering. Components may also become dimensionally
unstable. Both these effects prevent the heat treatment of die-castings as these phenomena are
detrimental to the visual appearance, mechanical properties and utilisation of the component.
Recent work has revealed a process window in which HPDC aluminium alloys that are
capable of responding to age hardening may be successfully heat treated without encountering these
problems. As a result, improvements of greater than 100% in the tensile properties are possible,
when compared with the as-cast condition. The new heat treatment schedules are described for
HPDC parts of different size and shape, the role of chemistry on ageing is discussed and
microstructural development during heat treatment examined†.
Influence of Cd and In on the Formation Kinetics of the δ' Metastable Phase in Al-Li-In(Cd) Alloys
Authors: Raho A. , Mouhyddine Kadi-Hanifi
Published: March 2009

The influence of the cadmium and the indium on the kinetics of the δ’ metastable
phase precipitation has been studied in Al-8.5at.%Li and Al-8.5%at.%Li-
0.2at.%In(0.3%at.%Cd) solid solutions. From the hardness isotherms the volumic fraction of
the formed δ’ metastable phase is determined for different times of ageing at 150, 180 and
200°C. The incubation times of δ’ deduced from the precipitation kinetics show that In and
Cd atoms retard the δ’ precipitation.