bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Heat Treatment on the Microstructure and Creep Behavior of Mg-Sn-Ca Alloys
Authors: Leil Tarek Abu , Huang Yuan Ding , Dieringa Hajo , Hort Norbert , Kainer Karl Ulrich , Buršík Jiří , Jirásková Yvonna , Rao Kamineni Pitcheswara
Published: March 2009

The development of new Mg-Sn based alloys that have shown improved corrosion
resistance needs further investigations to develop standard alloys for industrial use. In the present
study, the influence of heat treatment was investigated by examining the creep resistance of Mg-Sn
and Mg-Sn-Ca alloys at 85 MPa under 135 °C identify the best conditions to improve the mechanical
properties of such alloys. Additionally, the changes in microstructure of these alloys were studied and
analysed by light microscopy, X-ray diffraction and scanning electron microscopy. It was found that
the heat treatments can affect the microstructure of the binary alloy while no apparent change in the
microstructure was found in the Mg-Sn-Ca alloys, indicating that the second phase CaMgSn is
thermal stable in this alloy. Based on the obtained results, the relationship between the microstructure
and creep behaviour are discussed.
Low-Frequency Electromagnetic Field Influencing Horizontal Direct Chill Casting of Aluminum Alloy Rods
Authors: Zhao Zhi Hao , Cui Jian Zhong , Zhu Qing Feng
Published: March 2009

The horizontal direct chill (HDC) casting process is a well-established production route for
an aluminum alloy ingot; however, the ingot may suffer from inhomogeneous microstructures and
serious macrosegregation due to the unbalanced cooling condition and gravitational effect. In order to
control the defect, a low frequency electromagnetic field has been applied in the HDC casting process
and its influences on microstructures and macrosegregation have been studied. The results show that
the low frequency electromagnetic field can improve macrostructures, reduce inhomogeneous
microstructures and macrosegregation in HDC product; and two main parameters of the
electromagnetic field—density and frequency influence the microstructures and solution distribution
along the diameter of the ingot significantly. In the range of ampere-turns and frequency employed in
the experiments, the optimum ampere-turns and frequency have been found to be 10000At, 30Hz.
Numerical Simulation on Conform Process of Aluminum Alloy Rectangular Hollow Conductor
Authors: Wu Peng Yue , Wu Yu Cai , Xie Shui Sheng , Huang Guo Jie , Cheng Lei
Published: March 2009

In the investigation, the continuous extrusion forming (CONFORM) process of aluminum
alloy rectangular hollow conductor has been studied by three-dimensional finite-element method
based on Software DEFORM-3D. The rigid-viscoplastic constitutive equation was employed in the
model. Distributions of velocity field, strain field, stress field and temperature field were obtained in
the forming process. The results will give effective guidelines to optimize the processing parameters
and to select, the die structure and die materials.
Friction and Wear Properties of Friction Stir Welds of 5052 Al Alloy
Authors: Wang Xun Hong , Wang Kuaishe
Published: March 2009

Friction and wear behaviors have been studied between the untreated base material and
the friction stir welds of 5052 aluminum alloy. To determine the wear mechanism surface
microstructures of worn test samples were examined by scanning electron microscopy
(SEM).Variation rule of wear-resistance property and coefficient of friction were investigated
according to wear mass loss and moment of friction under different parameter condition. The results
show that all of friction stir welds had lower coefficients of friction and higher wear resistance than
base material. The abrasion loss of base material increased by six times when position pressure
increased from 50N to 100N and the abrasion loss is as 10-20 times as that of friction stir welds.
The value of friction-moment of friction stir welds is low and stable and abrasion principle had
changed from grain abrasion to fatigue wear. Surface examination showed that adhesion and
smearing was the main wear mechanism for friction stir welds.
Hot Deformation Behavior of 2519 Al Alloy during Isothermal Compression
Authors: Li Hui Zhong , Zhang Xin Ming , Chen Min Gan , Liu Ying , Gao Hui
Published: March 2009

The deformation behavior of 2519 aluminum alloy was studied by isothermal compression
by Gleeble-1500 simulator in the temperature range from 300 to 450°C under the strain rates of
0.01~10s-1. The results showed that the flow stress was controlled by strain rate and deformation
temperature. The flow stress increased with strain rate and decreased with deformation temperature.
The flow stress of 2519 aluminum alloy increased with strain and to the constant values at three strain
rates of 0.01 s-1,0.1 s-1and1 s-1, indicating the dynamic recovery to occur. The flow stress decreased
after a peak value with increase of strain at strain rate 10s-1 and deformation temperature higher than
350°C, showing partly dynamic recrystallization. The flow stress of 2519 aluminum alloy during high
temperature deformation can be represented by Zener-Hollomon parameter.
Removal of Na and Ca from Aluminum Scrap through Filtration
Authors: Görner Harald , Engh Thorvald Abel , Syvertsen Martin , Zhang Li Feng
Published: March 2009

Removal of Na by an “active” AlF3 filter seemed to be so efficient that all the sodium was
removed in the present experiments. The removal of Na is considered to be limited by the resistance
in the melt boundary layer only. However this is not the case for calcium. For calcium to be transfered
into the AlF3, resistance in the filter grains has to be taken into account in addition to the resistance in
the melt boundary layer. This was indicated by the total mass transfer coefficient of only 4x10-5 m/s.
A kinetic model was derived that can describe the removal of Ca from molten aluminum in an
“active” AlF3 filter by deep bed filtration following first order kinetics.
Study of Cu Addition on Precipitation Behaviors and Mechanical Properties in AA6082 Al-Mg-Si Alloy
Authors: Jin Man , Li Jing , Shao Guang Jie
Published: March 2009

The precipitation behaviors and microstructures of nano-precipitates in AA6082 Al-Mg-Si
alloy with and without Cu additions during heat treatment process were studied using hardness
measurements, TEM, mechanical tests and 3DAP. Meanwhile, the softening process of 6082 alloys
with Cu and without Cu, isothermally conditioned at 250°C, has also been investigated. It was found
that the rate of age hardening, mechanical properties and thermal stability are higher for the
Cu-containing alloy. The TEM and 3DAP observations showed that Q’ precipitates were existed
after aged at 170°C for 8h in the alloy with Cu addition. Comparing the hardness, mechanical
properties and thermal stability curves, it was concluded that the Q’ precipitates play a major role in
improving the age hardening kinetics and properties of 6082 alloy with Cu addition.
Small Angle X-Ray Scattering Study in Equal-Channel Angular Pressed 7055 Al Alloys
Authors: Zheng Li Jing , Li Guo Qiang , Li Huan Xi , Chen Chang Qi , Dong B.Z.
Published: March 2009

A study was conducted on 7055 Al alloys processed by Equal-channel Angular Pressing
(ECAP). The quantitative information about precipitate size, distribution and volume fraction in
ECAPed samples was investigated by small-angle X-ray scattering (SAXS) and transmission electron
microscopy (TEM). It is found that with the number of ECAP increasing, the quantitative information
about volume fraction (fv), precipitate size (R), specific inner surface of particle-matrix (Sp), and
integrated intensity (Q0) all increased, indicating that ECAP enhanced the nucleation and growth of
precipitates. The microhardness of samples after two passes of ECAP is higher than that of T6 treated
samples even after 96 h at 120°C. The formation of fine grains, higher volume fraction of precipitates,
together with strain hardening induced by severe deformation are the main factors leading to a high
microhardness in ECAPed samples.
The Application of Multiscale Modelling for the Prediction of Plastic Anisotropy and Deformation Textures
Authors: van Houtte Paul , Van Bael Albert , Seefeldt Marc
Published: March 2009

Finite element models for metal forming and models for the prediction of forming limit
strains should be as accurate as possible, and hence should take effects due to texture,
microstructure and substructure (dislocation patterns) into account. To achieve this, a hierarchical
type of modelling is proposed in order to maintain the balance between calculation speed (required
for engineering applications) and accuracy. This means that the FE models work with an analytical
constitutive model, the parameters of which are identified using results of multilevel models. The
analytical constitutive model will be discussed, as well as the identification procedure. The
multilevel models usually connect the macro-scale with a meso-scale (grain level) via a
homogenisation procedure. They can also be used to make predictions of deformation textures.
These will be quantitatively compared with experimentally obtained rolling textures of steel and
aluminium alloys. It was found that only models which to some extent take both stress and strain
interactions between adjacent grains into account perform well. Finally an example of a three level
model, also including the micro-scale (i.e. the dislocation substructure), will be given.
Deformation Mechanisms in High-Al Bearing High-Mn TWIP Steels in Hot Compression and in Tension at Low Temperatures
Authors: Hamada Atef S. , Karjalainen L. Pentti , Somani Mahesh C. , Ramadan R.M.
Published: March 2009

The hot deformation behaviour of two high-Mn (23-24 wt-%) TWIP steels containing 6 and 8 wt-% Al with the fully austenitic and duplex microstructures, respectively, has been investigated at temperatures of 900-1100°C. In addition, tensile properties were determined over the temperature range from -80 to 100°C. It was observed that in spite of the lower Al content, the austenitic steel possessed the hot deformation resistance about twice as high as that of the duplex steel. Whereas the flow stress curves of the austenitic steel exhibited work hardening followed by slight softening due to dynamic recrystallisation, the duplex steel showed the absence of work hardening and discontinuous yielding under similar conditions. Tensile tests at low temperatures revealed that the austenitic grade had a lower yield strength than that of the duplex grade, but much better ductility, the elongation increasing with decreasing temperature, contrary to that for the duplex steel. This can be attributed to the intense mechanical twinning in the austenitic steel, while in the duplex steel, twinning occurred in the ferrite only and the austenite showed dislocation glide.
Microstructure and Microtexture Evolution of a TRIP-Assisted Steel after Small Deformation Studied by EBSD Technique
Authors: Petrov Roumen H. , Kestens Leo , Houbaert Yvan
Published: March 2009

TRIP-assisted steel with a composition of 0.2%C, 1.5%Mn, 1.5% Al was studied in the
undeformed state and after the application of 20% tensile strain parallel to rolling the direction of
the sheet. The microstructure and microtexture of the steel sheets were examined in detail by means
of electron backscattered diffraction (EBSD) in order to quantify the microstructural constituents
and to study the strain distribution. The evolution of the microtexture and the distribution of the
specific texture components between the BCC and FCC phases were studied as a function of the external
strain. The strain localization and strain distribution between the structural constituents were
quantified on the base of the local misorientation maps. The full constraint Taylor model was used
to predict the texture changes in the material and the results were compared to the experimental
findings.
Comparing the local misorientation data it was found that at low strains the ferrite accommodates
approximately 10 times more deformation than the retained austenite. The strain localizes initially
on the BCC-FCC phase boundaries and then is spread in the BCC constituents (ferrite and bainite)
creating a deformation skeleton in the BCC phase.
The composite-like strengthening behaviour in TRIP-aided steel at 20% deformation might be
expressed by the decreasing free path of dislocations in ferrite due to the enlarging and thickening of
the multiphase skeleton as plastic deformation progresses, without changing significantly the main
texture components in the material.
Deformation and Heat Treatment of Cold Drawn Gold
Authors: Kang Suk Hoon , Cho Jae Hyung , Hwang Joon Sub , Cho Jong Soo , Park Yong Jin , Moon Jung Tak , Oh Kyu Hwan
Published: March 2009

Cold drawn gold wires are widely applied in electronic packaging process to interconnect
micro-electronic components. They basically provides a conducting path for electronic signal
transfer, and experience thermo-mechanical loads in use. The mechanical stability of drawn gold
wires is a matter of practical concern in the reliable functioning of electronic devices. It is known that
mechanical properties of materials are deeply related to the microstructure. With appropriate control
of deformation and heat processes, the mechanical properties of final products, such as tensile
strength and elongation can be improved. Severe plastic deformation by torsion usually contributes to
grain refinement and increment of strength. In this study, microstructure variations with torsion strain
followed by drawing and heat treatment were investigated. Analyses by focused ion beam (FIB) and
electron backscattered diffraction (EBSD) were carried out to characterize the effect of deformation
and heat treatment on the drawn gold wires. Pattern quality of EBSD measurements was used as a
quantitative measure for plastic deformation.
Annealing of Deformed Materials Developed by Continuous/Discontinuous Dynamic Recrystallization
Authors: Sakai Taku , Miura Hiromi
Published: March 2009

Annealing behaviour was studied in deformed copper developed by continuous or discontinuous dynamic recrystallization (cDRX or dDRX). Pure copper was deformed to large strains by multi-directional forging at room temperature, resulting in an ultra-fine grained structure due to operation of cDRX. Subsequent annealing of such a fine-grained copper can be controlled mainly by grain growth accompanied with recovery and no texture change, that is continuous static recrystallization (cSRX). On the other hand, 4 kinds of static restoration processes operate during annealing of dDRXed copper, i.e. metadaynamic recovery and recystallization (mDRV and mDRX), and classical static recovery and recrystallization. The stable existence of mDRVed grains containing moderate dislocations leads to incomplete recrystallization even after a long period of annealing time. It is discussed how such various types of annealing processes, occurring in cDRXed or dDRXed matrices, can be connected with the characteristic nature of the deformed microstructures.
Effects of Solubility Limit and the Presence of Ultra-Fine Al6Fe on the Kinetics of Grain Growth in Dilute Al-Fe Alloys
Authors: Saimoto Shigeo , Jin Hai Ou
Published: March 2009

A nominally pure Al slab was thermo-mechanically treated to result in a near random texture of 90 m grain size. Subsequent cold rolling with intermediate anneals at 230, 275, and 300°C reduced the Fe solute to near equilibrium compositions below 0.5 ppm atomic. The final cold rolled sheet continuously recrystallized; grain growth of this structure is reported. A grain-growth kinetics mapping was generated, correlating the parameters of Fe-in-Al solubility limit, Fe diffusivities in the grain boundaries and the Al lattice and the activation energies for migration rates.
Effect of Low-Temperature Recovery Treatments on Subsequent Recrystallization in Al-2.5%Mg
Authors: Decreus B. , Zurob Hatem S. , Dunlop John , Bréchet Yves
Published: March 2009

The effect of low temperature recovery treatments on the recrystallization kinetics during
subsequent high temperature annealing was investigated in three Al-2.5%Mg alloys with various Fe
additions. Recovery treatments were carried out at 190oC for times ranging from 0.25 to 65 hrs.
Recrystallization treatments were carried out at 280oC. The kinetics of recrystallization was
followed using the techniques of hardness measurement, optical metallography and calorimetry.
Retention of the ‹001› Fiber Texture for Fe-Si Electric Motor Steels
Authors: Doherty Roger D. , Stojakovic D. , Landgraf Fernando José Gomes , Kalidindi Surya R.
Published: March 2009

The ideal sheet texture for electric motor steels, the λ fiber, with 〈001〉 normal to the rolling plane, that can be produced by directional solidification, is largely lost by the required heavy rolling reduction and recrystallization needed to produce thin motor laminations. However by two successive light rolling reductions, followed in each case by recrystallization, the desired texture was largely recovered. Taylor and finite element modeling supported the hypothesis for this successful processing: the low Taylor factor of the λ fiber grains. Although starting from similar grain sizes, the second light deformation produced a much larger recrystallized grain size than did the first light deformation. This result suggests that a lower average Taylor factor in the structure before deformation, resulting in lower stored energy, can increase the recrystallized grain size.
Kinetics, Mechanism and Modeling of Microstructural Evolution during Dynamic Recrystallization in a 15Cr-15Ni-2.2Mo-Ti Modified Austenitic Stainless Steel
Authors: Mandal Sumantra , Sivaprasad P.V. , Dube R.K. , Raj Baldev
Published: March 2009

Kinetics, mechanism and modeling of the microstructural evolution of a 15Cr-15Ni-
2.2Mo-0.3Ti modified austenitic stainless steel (alloy D9) during dynamic recrystallization (DRX)
have been investigated. The kinetics of DRX has been investigated employing a modified Johnson-
Mehl-Avrami-Kolmogorov (JMAK) model. The microstructural study shows that nucleation of new
grains during DRX takes place on the parent grain boundary by a bulging mechanism. No
significant texture component has been found to develop in the recrystallized matrix. A substantial
amount of twins have been observed in the recrystallized matrix. It is proposed that twins play an
important role during the nucleation and subsequent expansion of DRX in alloy D9, which in turn
moderates the texture in the recrystallized matrix. An artificial neural network model has also been
developed to predict the fraction of DRX and grain size, as a function of processing conditions. A
good correlation between experimental findings and predicted results has been obtained.
Biaxial Tensile Deformation Behavior and Microstructural Evolutions of Superplasticity in AZ31 Magnesium Alloy
Authors: Noda M. , Shimizu Hideharu , Funami Kunio , Mori H.
Published: March 2009

Magnesium alloys show promise in meeting the demand for materials of lighter weight and
higher rigidity. Mg alloys are hard to process and normally require grain refining for improved
formability and mechanical properties. To process these fine-grained Mg alloys effectively, it is
important to relate their load stress and mechanical properties to changes in their microstructures.
Using a biaxial tensile machine and cruciform specimens, to evaluate the mechanical properties,
microstructure, and plasticity, in a high temperature biaxial stress state, used of AZ31 Mg alloy sheet.
With biaxial deformation, grain boundary slide occurred more frequently than with uniaxial
deformation, causing grain boundary separation and formation of micro-voids between the grains. In
the vicinity of the cracks and at the locations of grain boundary separation, although deformation
temperature at higher than the recrystallization temperature, fine grains (about 2 )m) showing in
duplex grain structures were formed locally. The formation of duplex grain structures as a result of
local formation of fine grains during the deformation process is a major issue to be solved from the
viewpoint of plasticity processing.
Numerical Simulation of Superplastic Forming of a Magnesium Alloy Part
Authors: Jin Quan Lin , Zeng Zhi Peng , Zhang Yan Shu
Published: March 2009

A numerical simulation of superplastic backward extrusion of a magnesium alloy part is
presented in this paper. In fact, the simulated superplastic forming is not a pure superplastic forming
because of the billet with coarse cylindrical grains. The forming may become a pure superplastic
forming only after dynamic recrystallization and grain refinement appear and the grain boundary
sliding has been the main deformation mechanism. In order to simulate the special forming process, a
constitutive relation considering dynamic recrystallization and the multiform deform mechanism and
the parameter identification of the constitutive relattion are studied. The program for simulation is
able to predict the grain refinement and the transform between different deformation mechanisms.
Finally the calculated results on the grain size and dynamic rerystallization are presented. A
comparison between the calculated and the experimental results shows there is a good agreement
between calculated results and experimental results.
Superplastic Deforming Analysis Based on Element Free Galerkin Method
Authors: Yang Yu Ying , Li Jing
Published: March 2009

Superplastic large deformation problems always meet handicaps associated with severe
mesh distortion and iterative remeshing when traditional mesh-based numerical approaches are used.
To eliminate these difficulties, meshless simulation of element free Galerkin method (EFGM) for
rigid-viscoplastic(RVP) model and incompressible materials is built upon the Moving Least Squares
(MLS) approximation and modified Markov variational principles. Also, a numerical quadrature that
aligns integration cells with the local supports of shape functions is presented to compute integrations
involved in the objective functions. Satisfying results of a superplastic upsetting example with very
large compression ratio demonstrate the feasibility and accuracy for the meshfree method to simulate
superplastic large deformation process.
Numerical-Experimental Characterization of a Superplastic AZ31 Magnesium Alloy
Authors: Palumbo G. , Sorgente Donato , Tricarico Luigi , Zhang S.H. , Zheng W.T. , Zhou L.X. , Ren Li Mei
Published: March 2009

In this work the superplastic behaviour of a hot rolled AZ31 magnesium alloy sheet under a
biaxial tension test with the blow forming technique is presented and reported. The specimen dome
height and its thickness distribution, during and after the test, have been used as characterizing
parameters. A numerical FE model of the test has been developed in order to easily characterize the
material and to directly analyze experimental results. The influence of the rolling cycle on the
microstructure and consequently on the material behaviour has been also analyzed. A synergic use of
experimental results and of the numerical model has been done for finding material constants in
different situations. The material flow parameters have been found and results are presented.
Superplasticity in CP-Titanium Alloys
Authors: Zhu X.J. , Tan Ming Jen , Liew K.M.
Published: March 2009

In this work, studies were carried out to investigate the superplasticity of a commercially
pure (CP) titanium alloy during high temperature deformation. Uniaxial tensile tests were carried out
at 600, 750 and 800°C with an initial strain rate from 10-1s-1 to 10-4s-1. It was found that the alloy do
not show good superplasticity due fast grain growth at high temperature and cavity. The effects of
temperature on the grain growth and cavity phenomena as well as the dynamic recrystallization of the
alloy were studied and a ‘two-step-method’ was introduced to increase the superplasticity of the alloy.
Effect of Hydrogenation on the Microstructure during the Isothermal Compression of Ti-5.6Al-4.8Sn-2.0Zr-1.0Mo Alloy
Authors: Lin Ying Ying , Li Miao Quan , Niu Y. , Zhang W.F.
Published: March 2009

Isothermal compression tests were carried out on the Ti-5.6Al-4.8Sn-2.0Zr-1.0Mo alloy
with and without hydrogen. A series of experiments including the optical microstructure and TEM
(Transmission Electron Microscope) were performed to the compressed samples. The results show
that hydrogenation not only increases the fraction ofβ phase, but also activates the propagation of the
dislocation and formation of the twins, which are benefit for plastic or superplastic formability.
Superplastic Behavior and Microstructural Evolution of GH4169
Authors: Xu H.Y. , Li Zhi Qiang , Guo He Ping
Published: March 2009

Tensile testing was performed on fine-grained GH4169 superalloy sheet at elevated
temperatures (920°C~980°C) and at different initial strain rates (10-4~10-2s-1). The maximum
elongation obtained was 280%. By TEM, active dislocation movement was observed and compared at
different strain level and strain rate. Dynamic recovery and recrystallization was also found during
superplastic deformation that played an important role of softening. At last the superplastic
deformation mechanism of GH4169 alloy was discussed.
Superplastic Phenomenon in Sc2O3 Doped Zirconia Polycrystals to be Used for SOFC
Authors: Motohashi Yoshinobu , Ishimura H. , Kobayashi Y. , Sakuma Takaaki
Published: March 2009

The 4mol%Sc2O3 doped ZrO2 (4ScSZ) showed a superplastic-like large elongation in a
range of strain-rate at 1773K. The large elongation was caused by both of high strain-rate sensitivity
and high strain hardening during the deformation. Ion conductivity of the 4ScSZ, deformed
superplastically at a relatively high strain-rate region, was higher than that of non-deformed one,
suggesting that superplastic deformation can improve its conductivity. These results are discussed
with probable microstructural evolution.
Superplastic Sinter-Forging of Fine-Grained Si3N4-Si2N2O Composite at Low Temperature
Authors: Luo Jun Ting , Zhang Qing
Published: March 2009

The Si3N4- Si2N2O composites are fabricated with amorphous nano-sized silicon nitride
powders by the liquid phase sintering (LPS) method. XRD analysis shows sintered body consists of
β-Si3N4 and Si2N2O. SEM experiment conforms that the average grain size of sintered body is less
than 300nm. The complex-shape gears can be formed by a sinter-forging technology when the
sintering temperature is 1600°C and the superplastic forging temperature is only 1550°C. Rod-shaped
grains aligned along the perpendicular direction of pressure and the mechanical properties increase
about 10% after the materials were forged.
Superplastic Extrusion of Ultra Fine-Grained 3Y-TZP/Al2O3 Ceramic for Turbine Disk
Authors: Wang F. , Zhang Kai Feng , Han Wen Bo
Published: March 2009

Superplastic extrusion of axial forcing and radial flowing under different conditions was
adopted to form a turbo-rotor, using hot-press sintered compact of zirconia (3Y)-toughened alumina
composite that was prepared at 1450 °C for 1 hour with relative density of higher than 96%.
Subsequent superplastic extrusion was attempted at temperature of 1500 °C-1650 °C. The results
indicate that 3Y-ZrO2 plays an important role as a second-phase pinning agent and inhibits grain
growth. The material shows good deformability and potential of near-net-shape forming. Comparing
with undeformed sample, extruded sample was observed apparent coarsening in grain size and the
remaining mechanical properties after deformation are not improved, irrespective of improved
density. The dominating deformation mechanism is grain sliding and rotation accommodated with
zirconia coordinated deformation.
Effect of Superplastic Deformation on the Properties of Zirconia Dispersed Alumina Nanocomposite
Authors: Chen Guo Qing , Sui Shao Hua , Wang X.D. , Han Wen Bo
Published: March 2009

In this paper constrained extrusion of the zirconia dispersed alumina nanocomposite under
superplastic conditions was conducted. The mechanical properties of deformed material were studied
and its results were compared with those of the initial materials. The microstructure evolution during
superplastic deformation was also analyzed. The results demonstrated that after superplastic extrusion
the flexural strength, relative density, Vickers hardness as well as fracture toughness of the material
increased noticeably. The flexural strength of the deformed composite even retained at a high value of
310MPa at 800°C. The fracture toughness of the material increased from 6.92 MPa·m1/2 to 8.87
MPa·m1/2 after deformation. After superplastic extrusion due to grain boundary sliding and the
compressive stress state, the internal porosities in as-sintered materials were eliminated. During
extrusion with grain coarsening the effect of t-ZrO2 to m-ZrO2 transformation toughening increased
because more zirconia grains reached the critical dimension. Although grain coarsening may cause
the decrease of the fracture toughness in some extent, the phase transformation toughening and
strengthening dominated. As a result, the mechanical properties of the deformed material were
improved.
Low Temperature Superplasticity of Titanium Alloy Processed by Thermohydrogen Treatment
Authors: Li Zhi Qiang , Hou Hong Liang , Wang Y.Q.
Published: March 2009

Effects of hydrogen on superplastic deformation behavior were investigated through high
temperature tensile experiment in this paper. It is found that reasonable hydrogen contents can
improve the superplastic behavior such as lowering flow stress and temperature and increasing m
value. While addition of 0.1wt% hydrogen in Ti-6Al-4V alloy, peak flow stress decrease to 53%,
deformation temperature decrease 60°C. The influence of hydrogen on microstructure transition by
means of optic microscope, SEM, TEM and XRD was also researched. The results show that β phase
amounts in the hydrogenated alloy increase with hydrogen contents, while hydrogen contents reach to
0.2wt%, martensite becoming coarser with the increase of hydrogen contents. Moreover, dislocations
density of hydrogenated alloy after deformation is lower than that of unhydrogenated alloy because of
hydrogen action.
Overview of FSW Project in Osaka East Urban Area Industry-Government-Academia Collaboration
Authors: Tsujikawa Masato , Marutani Yoji , Higashi Kenji
Published: March 2009

Friction Stir Welding (FSW) for aviation and automobile applications has been
investigated at Osaka East Urban Area Industry-Government-Academia Collaboration Project on
FSW sponsored by a Japanese ministry of education, culture, sports, science and technology,
2004-2007. The objective of this project is the three dimensional (3D) FSW of light metallic
materials. The project consists of two simultaneous investigations. One is the approach from material
side. The establishment of optimum FSW conditions and the construction of the FSW equation
between weld condition and formed microstructure. The other is the approach from 3D software. The
construction of optimum algorism for 3D FSW is the main theme. The construction of 3D FSW
expert system for aluminum alloys, magnesium alloys and titanium alloys is the goal of us in
combination of the results developed by the two research group.
Research on the Superplastic Forming of Copper Alloy Solid-Bearing Cages Used in Railway Vehicles
Authors: Yang Yong Shun , Chen Guo Qing , Chen F.X.
Published: March 2009

In this paper uniaxial tensile tests were carried out at temperature range of 650~810°C and
initial strain rate range of 10-4~10-1s-1 to evaluate the superplasticity of as-casting aluminum-bronze
QAl10-3-1.5 alloy. The superplastic forming technology (SPF) was adopted to produce solid-bearing
cages made of aluminum-bronze QAl10-3-1.5 alloy. The results demonstrate that as-casting
QAl10-3-1.5 copper alloy shows good superplasticity without prior-treatment. The maximum
elongation of 545% is obtained at 790°C and initial strain rate of 1.0×10-2 s-1, while the maximum
flow stress is only 12.4MPa.
By using superplastic extrusion technology solid-bearing cages used in railway vehicles were
obtained. As-extruded cages have good surface quality and the dimensional accuracy satisfies the
design standards. Using this technology the production efficiency is greatly enhanced and the
manufacturing cost is reduced, especially the expensive copper alloys are saved.
Advances in the Superplastically Formed and Diffusion Bonded Process
Authors: Hefti Larry D.
Published: March 2009

The Superplastically Formed and Diffusion Bonded (SPF/DB) titanium structure in
production today for Boeing products, not including engines, are all diffusion bonded using matched
metal tooling and are all fabricated using the common 6Al-4V alloy. The matched metal tooling
concept presents a challenge in obtaining high quality bonds over large areas where direct tool
pressure is being used to place the titanium sheets into contact with each other. This is due to
tolerance build-up in the tools and in the titanium sheets that are used to fabricate the components.
Also, because the parts are partially formed before bonding begins, material has been pulled away
from the bonding area and the thickness in that location is now less than what the tool was designed
for which makes achieving a good quality bond even more challenging. Boeing Commercial
Airplanes (BCA) is currently advancing the state of the SPF/DB process in several ways. One of these
advances is using a different approach for diffusion bonding. The process includes using stop-off
between the sheets and diffusion bonding the pack first and then superplastically forming the
stiffening features. This generates a component that is very well bonded in the required locations.
However, this process also has its challenges. One of these involves how to apply the stop-off material
in the proper location using the most cost effective process. Historically, the application method has
been silk screening. A new method has been developed for applying the stop-off that eliminates the
need for several pieces of equipment that are required for the silk screening process as well as the
associated floor space. Another advancement has been in the development of a different titanium
alloy for use in SPF/DB structure.
Amplification of the Thermocapillary Convection during Evapo-Condensation Cycle in Heat Pipes
Authors: Bennacer Rachid , El Ganaoui Mohammed
Published: March 2009

The control of a process dealing with heat pipe exploitation needs the thermal analysis of
the evaporation-condensation cycle and noticeably the imposed external conditions (in instance
modeling the heating). In this work a numerical model has been developed to describe the local
coupling near the liquid/vapour interface. Simulations exhibits and quantify the response of the
capillary motion to the thermal conditions.
Design of Moving Components of an Ultra Precision Machine Tool for Nanometric Machining
Authors: Vahdati Mehrdad , Shokuhfar Ali
Published: March 2009

Ultra precision machines are used for very precise machining as well as small parts. Due to their application, the accuracy of products has been upgraded in recent years. Thus, dimensional accuracies could be compared with surface texture dimensions like roughness and etc. In order to attain dimensions with surface texture accuracy, usually micro/nano meter, it is necessary to adopt ordinary machining technologies with micro/nano techniques. This measuring by adoption leads to nano-machining. Nano-machining researches deal with all three basic components of, machine tools, work piece, and cutting tool, which have fundamental importance for development of this technique. Despite of wide range of possible researches, only part of design points of ultra precision machines have been considered in this report. Air operated systems, like air slide table, and air spindle are examples of ultra precision machine tool components. These two components have been analyzed for some of their characteristics. Experiments have been planed to extract the relationship between stiffness, employing some of the effective parameters such as air pressure and air gap. The results describe the performance condition of air table and air spindle under different loadings.
Influence of the Morphology of Joining on the Heat Transfer Properties of Periodic Metal Hollow Sphere Structures
Authors: Fiedler Thomas , Öchsner Andreas
Published: March 2009

Hollow sphere structures (HSS) constitute a group of innovative materials which are characterised by more constant material properties compared to classical cellular metals [1]. Their big potential lies within multifunctional applications where combinations of their proper- ties yield symbiotic advantages. In the scope of this paper their effective thermal conductivity is investigated. In addition to the analysis of the dependency of this material parameter on the conductivities of the base materials and the sphere wall thickness, special focus is given to the influence of the morphology of joining.
Finite Element Verification of Transmission Conditions for 2D Heat Conduction Problems
Authors: Mishuris Gennady , Miszuris Wiktoria , Öchsner Andreas
Published: March 2009

Imperfect transmission conditions modelling a thin 2D intermediate layer between
two bonded materials in a dissimilar strip have been derived and analytically analysed in
another paper of this issue. In this paper, the validity of these transmission conditions for heat
conduction problems has been investigated due to the finite element method (FEM) for various
cases: namely, steady-state under uniform boundary conditions with constant or functional-
dependent, i.e. temperature or spatial coordinate, conductivities of the interphase, non-uniform
boundary conditions and finally for transient analysis. It is shown that the accuracy of the
transmission conditions is excellent over the whole range of the interphase and that typical
edge effects known from structural problems are not observable under the chosen problem
parameters.
Role of α-SiAlON Nuclei Addition on the Rod-Like Y-Sm α-SiAlON Formation
Authors: Kushan S.R. , Acikbas N.C. , Křest'an J. , Šajgalík Pavol , Mandal Hasan
Published: March 2009

In this study, effect of seed addition on the microstructural development of Y-Sm α-SiAlON system has been investigated. Besides using pre-produced rod-like α-SiAlON seeds, growth in the glassy phase and harvested by chemical treatment, powdered Y-Sm/α-SiAlON was also used as nuclei. Microstructural results of both systems were compared with un-seeded samples. It was found that the powdered α-SiAlON addition has also caused the acicular α-SiAlON grain formation, which indicates the dominant effect of thermodynamic stability on the preferential growth of α-SiAlON grains in the c direction.
Silicon Nitride – Carbon Nanotube Composites
Authors: Balázsi Csaba , Czigány Zsolt , Wéber Ferenc , Kónya Zoltán , Vértesy Zófia , Biró László Péter , Kiricsi Imre , Arató Péter
Published: March 2009

Multiwall carbon nanotube reinforced silicon nitride composites have been prepared by hot isostatic pressing. A manufacturing process has been worked out to avoid the damage of nanotubes during sintering. This method provides their preservation even in severe circumstances at temperature 1700°C and gas pressure 20 MPa. As shown by scanning and transmission electron microscopy after low and high pressure processing, carbon nanotubes have good adherence to the silicon nitride grains. Moreover, carbon nanotubes have been found to be located not only at grain surfaces, but in several cases they are well integrated with the silicon nitride grains. Composites with higher strengths can be obtained by increasing the nitrogen gas pressure.
Particle -Reinforced SiAlONs for Cutting Tools
Authors: Bitterlich Bernd , Friederich Kilian
Published: March 2009

CeramTec AG is a well-known manufacturer of cutting tool materials, especially for inserts based on silicon nitride. Some years ago it started the production of alpha/beta-SiAlONs because of their superior properties. Due to strong competition in the cutting tool business there is a constant need for further development of the cutting tool materials. One possibility to increase wear resistanceand life time of cutting tools is to increase the hardness and maintaining the good toughness at the same time. This can be done by adding hard particles like e.g. SiC to an alpha/beta- SiAlON. In 2003 an improved grade had been presented: a SiC-reinforced alpha/beta-SiAlON. This composite material shows a significantly reduced wear during machining of cast iron. The effect of SiC-addition on mechanical properties is discussed.
Transformation Potential of Kalemaden Clay – 220 to Technological Ceramics
Authors: Yilmaz R. , Kurt A.O.
Published: March 2009

In this study, the Clay – 220 mineral of Turkish origin from Kalemaden A.S., having a composition of the quarts, kaolinite, feldspar and the others with the weight percent of 36.20, 12.66, 48.03 and 3.11, respectively, was used as a raw material to investigate its transferability potential to a technological ceramic. The mineral was in the form of conglomerate rocks, which were prepared in the consecutive mineral processing procedures before taken it to the stage where carbothermal reduction - nitridation (CRN) was performed in an atmosphere controlled environment. Various process parameters, i.e., temperature, time and N2 – flow rate were tested in order to optimise the CRN process. SiAlON was formed at temperatures as low as 1300oC and its content increased with reaction temperature up to 1475oC. Above 1425oC, SiC becomes more predominant phase in the powdered product after CRN. Fine powders formed at temperature of 1350oC, which is the lowest value reported among the current literature, contain single crystalline phase of β-SiAlON. The results indicated that the best transformations and yield to the SiAlON ceramic were occurred on the previously prepared Clay – 220 samples in powder form that were processed at 1350oC for 6 hours with nitrogen flow rate of 1 lt/min.
Microstructural Aspects of the Hot-Pressed Hexagonal Boron Nitride Ceramics with Limited Content of Boron Oxide
Authors: Ertug B. , Boyraz T. , Addemir O.
Published: March 2009

Hexagonal boron nitride (h-BN) based ceramics have been fabricated by hot-pressing in a
nitrogen atmosphere at 1900°C for 60 min. under a pressure of 50 MPa with B2O3 as sintering
additive. The phase composition was confirmed by XRD. The microstructural properties of h-BN
powders and hot-pressed surfaces were evaluated by SEM-EDS analysis. The formation of the
secondary phase was also investigated with particular interest on grain boundaries. The sintered
densities were also determined by Archimedes’ method. The maximum relative density was
obtained to be about 92 %. The effect of the existence of boron oxide on the boron nitride grain
growth behaviour was discussed on the basis of microstructural features.
Utilization of a Phosphate Ester as a Dispersant for SiAlON Based Ceramics
Authors: Ceylan A. , Suvaci E. , Mandal Hasan
Published: March 2009

Aqueous dispersions of SiAlON forming powders (Si3N4, AlN and Y2O3) were obtained. Dispersibility of powders was found to be improved by addition of sodium tripolyphosphate. Stable aqueous suspensions of SiAlON forming powders were prepared by using a phosphate ester, sodium tripolyphosphate (STPP, Na5P3O10). Effect of the STPP on rheological properties of the powder mixture was investigated by zeta potential measurements, sedimentation and milling studies. It has been shown that addition of the STPP to the aqueous SiAlON forming powder mixture improves the dispersion behavior significantly. These results suggest that STPP can be utilized as a dispersant in such ceramic systems.
Fabrication of Porous β-SiAlON Preforms from Kaolin for Liquid Metal Infiltration
Authors: Demir Adem , Caliskan F.
Published: March 2009

In this study, the production of β-Si6-zAlzOzN8-z (z =3) powders by the carbothermal
reduction and nitridation of kaolin (Al2O3.2SiO2.2H2O) of Turkish origin (Can-Canakkale) was
carried out with different processing parameters. It was found that the morphology of the produced
SiAlON powder was mixture of irregular and whisker like grains. Therefore this morphology is
suitable for liquid metal infiltration since the powders are already high porous. The kaolin powder
containing stoichiometric rate carbon black and 30 % charcoal were pressed and reacted under
nitrogen flow (2 lt/min) between 1400-1475°C for 4 h. After a carbothermal reduction and
nitridation (CRN) process, porous β- SiAlON ceramic was produced from natural kaolin. Residual
carbon and charcoal in the produced ß-SiAlON ceramic were fired at 1000°C giving extra porosity.
The porous ß-SiAlON ceramics were sintered under N2 atmosphere at 1550°C for 2 h to make
preform for infiltration process. SEM image analyses were carried out to determine preform and
pore morphology and XRD analysis were performed for phase transformation.
Simulation Study of Granular Compaction Dynamics under Vertical Tapping
Authors: Arsenović D. , Vrhovac S.B. , Jakšić Z.M. , Budinski-Petković Lj. , Belić A.
Published: March 2009

We study by numerical simulation the compaction dynamics of frictional hard disks in
two dimensions, subjected to vertical shaking. Shaking is modeled by a series of vertical expansions
of the disk packing, followed by dynamical recompression of the assembly under the action of
gravity. The second phase of the shake cycle is based on an efficient event−driven
molecular−dynamics algorithm. We analyze the compaction dynamics for various values of friction
coefficient and coefficient of normal restitution. We find that the time evolution of the density is
described by ρ(t)=ρ∞ − ρEα[−(t/τ)α], where Eα denotes the Mittag−Leffler function of order
0<α<1. The parameter τ is found to decay with tapping intensity Γ according to a power law τ ∝
Γ−γ
, where parameter γ is almost independent of the material properties of grains. Also, an
expression for the grain mobility during compaction process has been obtained.
Theoretical Assessment of Calcium Arsenates Stability: Application in the Treatment of Arsenic Contaminated Waste
Authors: Raičević S. , Stanić V. , Kaludjerović-Radoičić Tanja
Published: March 2009

Several approaches for immobilization of arsenic (As) based on the transformation of its
soluble forms (compounds) into highly insoluble arsenate apatite Ca5(AsO4)3OH have been
proposed. These immobilization techniques are successfully applied in treatment of industrial waste
containing As. Quite the contrary, treatment of soil contaminated with As by apatite amendments,
instead of immobilization of this toxic element, increases its mobility and bioavailability. The
mechanism underlying these opposite effects still remains elusive. Here, the stability analysis of
different calcium arsenates: Ca5(AsO4)3OH, Ca4(AsO4)2(OH)2, Ca3(AsO4)2 Ca5H2(AsO4)2 and
CaHAsO4 was performed, which is based on the calculation of the ion-ion interaction potential
(IIIP). It has been demonstrated earlier that IIIP, representing the main term of the cohesive energy,
is a suitable parameter for assessment of mineral stability. According to the results of this analysis,
arsenate apatite with IIIP value of -0.578 Ry represents the most stable chemical form among
analyzed compounds. Based on this finding, we proposed a mechanism of formation of arsenate
apatite in the presence of hydroxyapatite. This mechanism can explain the suitability of this
approach for the treatment of industrial waste and its limitations for in situ treatment of soil and
water contaminated with As.