bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of C on Vacancy Migration in α-Iron
Authors: Fu Chu Chun , Meslin Estelle , Barbu Alain , Willaime F. , Oison V.
Published: March 2009

Carbon atoms are always present in Fe-based materials, either as impurities even in high
purity samples or as an intrinsic constituent in steels. Density Functional Theory calculations have
been performed to study the interaction between C atoms and vacancies (V) in α-Fe. We find that
the formation of VCn complexes is energetically favourable for n ≤ 3, with VC2 being the most
stable one. The energy gain corresponding to the clustering reaction VCn-1 + C → VCn depends
mainly on the strength of C-C covalent bonds. The vacancy diffusivity is shown to be significantly
modified by the formation of vacancy-carbon complexes, exhibiting non-Arrhenius behaviour.
Effective vacancy diffusion coefficients in α-Fe are calculated as a function of temperature and
carbon content using a simplified thermodynamic model. The results are discussed in detail in the
limiting case of excess of C with respect to vacancies.
In-Diffusion and Out-Diffusion of Oxygen from a Composite Containing Random Traps
Authors: Belova Irina V. , Murch Graeme E.
Published: March 2009

In this paper, we investigate oxygen in-diffusion and out-diffusion with respect to a cermet
composite where oxygen segregates at the interface between the metal matrix phase and the
ceramic oxide phase. This phenomenological diffusion problem is treated by overlaying it with a
fine-grained lattice that was addressed using a Lattice Monte Carlo method and a little-known exact
expression for the lattice-based effective diffusivity in the presence of random traps. It is shown that
there is very good agreement for the oxygen concentration depth profiles between the Monte Carlo
results and the exact expression.
Effects of Supports on Hydrogen Adsorption on Pt Clusters
Authors: Okazaki-Maeda K. , Morikawa Y. , Tanaka Shingo , Kohyama Masanori
Published: March 2009

Pt nano-particles are supported on carbon materials at the electrode catalysts of protonexchange
menbrane fuel cells. Pt nano-particles are desirable to be strongly adsorbed on carbon
materials for high dispersion, although strong Pt-C interactions may affect the catalytic activity of
small clusters. Thus we have examined H-atom absorption on Pt clusters supported or unsupported
on graphene sheets, using first-principles calculations. For Pt-atom/graphene systems, a H atom is
more weakly adsorbed than for a free Pt atom, and the H-Pt interaction becomes weaker if the
interaction between a Pt atom and graphene becomes stronger. For the Ptn-cluster/graphene systems
(n=2-4), the H-Pt interactions are also substantially changed from those for free Pt clusters. In the Pt
clusters on graphene, the Pt-Pt distances are substantially changed associated with the electronicstructure
changes by the Pt-C interactions. These structural and electronic changes in the Pt clusters
as well as the presence of graphene itself seem to cause the changes in the absorption energies and
preferential sites of H-atom absorption.
Nanotechnology for Treating Damaged Organs
Authors: Lu Jing , Webster Thomas J.
Published: March 2009

Atherosclerosis, which is caused by endothelial dysfunction, vascular inflammation, and
the build-up of lipids, cholesterol, calcium, and cellular debris within the intima of the vessel wall,
is one of the most important complications of health. Vascular stenting is the procedure of
implanting a thin tube into the site of a narrow or blocked artery due to atherosclerosis. However,
the application of vascular stents using conventional metals is limited because the implantation
process will cause significant injury to the vascular wall and endothelium, which functions as a
protective biocompatible barrier between the tissue and the circulating blood, resulting in neointima
hyperplasia followed by the development of long-term restenosis. The objective of this in vitro
study was to investigate the endothelial cell function, especially their adhesion behaviour, on highly
controllable features on nanostructured surface. Considering the importance of the endothelium
and its properties, highly controllable nanostructured surface features of titanium, a popular
vascular stent metal, were created using E-beam evaporation to promote endothelialization and to
control the direction of endothelial cells on vascular stents. Endothelial cells are naturally aligned
with the blood flow in the body. In this manner, the present in vitro study provides much promise
for the use of nanotechnology for improving metallic materials for vascular stent applications.
Dielectric Relaxation of a Cholesterol Domain Near a Graphite Wall - A Computer Simulation
Authors: Raczynski P. , Gburski Z.
Published: March 2009

Molecular dynamics (MD) studies are presented for a cholesterol domain near a graphite
wall. The dynamic observables of cholesterol at the physiological temperature of 309 K were
investigated. Attention was focused on the total dipole moment
→
M autocorrelation function
( ) ( ) ( ) / (0)2
∧ → → →
C t = M t ⋅M t M and the dielectric loss spectrum ε’’(ν). Additionally, the comparison
with the dielectric relaxation of a pure cholesterol cluster without a graphite wall is presented and
discussed.
Stability, Instability, Metastability and Grain Size in Nanocrystalline Ceramic Oxide Systems
Authors: Kimmel Giora , Zabicky Jacob
Published: March 2009

The following nanocrystalline binary oxide systems were studied: Mg-Ti, Ni-Ti, Zr-Al, as
well as some pure and doped unary oxides. The xerogels were heated at a constant T (200 to
1600°C) for 3 to 6 hours. There was a threshold tempearture for oxide formation and in many cases
the products were metastable nanocrystalline phases, depending on the grain size and composition,
including doping. The oxide phases of Ni-Ti, Mg-Ti, and Zr-Al, formed at 900 °C are different from
those formed at higher temperature. New ranges of solid solutions and the formations of higher
temperature structures were found. A transition phase can be defined as a structure formed at
relative low tempearture, irreversibly transforming at higher temperature into an equilibrium phase
of the same elemental composition. Some low temperature transition phases have a structure
similar to that of a high temperature equilibrium phase, e.g., (the equilibrium phase is given in
parentheses) tetragonal ZrO2 (monoclinic) and low-T qandilite-like solid solutions (qandilite +
geikielite). Others are unique with no representation in the equilibrium phase diagram, e.g.,
gamma-like alumina (corundum) and anatase (rutile), which are formed as nanocrystalline oxides
due to a low growth rate caused either by a low temperature of calcination or due to additives.
To asses the importance of crystal size in the stabilization of transition phases, the following studies
were undertaken: (a) XRPD analysis of all unary, doped and binary compositions; (b) the evolution
of transition phases in HT XRPD of the Mg titanates; (c) the phase evolution was studied with time
at temperatures were mixtures of transition and equilibrium phases were found; (d) the retention of
pure tetragonal ZrO2 on quenching Al-Zr oxides after calcinations at high tempetature; (e)
additional evidence from HRTEM, SEM and DTA experiments was also collected. A model,
correlating the size effect with the unusual phases and structures is proposed.
Nanosized Barium Hexaferrite Powders Obtained by a Single Microemulsion Technique
Authors: Koutzarova Tatyana , Kolev Svetoslav , Grigorov Kornely Grigoriev , Ghelev Chavdar , Nedkov Ivan , Ausloos Marcel , Cloots Rudi , Mydlarz Tadeusz , Zaleski Andrzej
Published: March 2009

Barium hexaferrite (BaFe12O19) powders of particle size of 130 and 180 nm were
synthesized by a single microemulsion technique. The influence of the concentration of Ba2+ and
Fe3+ metallic ions in the aqueous phase in the microemulsion system on the particle size
distribution, crystallinity and magnetic properties of BaFe12O19 was studied. The coercive force and
saturation magnetization of the sample obtained at a lower concentration of metallic cations in the
aqueous phase were higher than those of the sample obtained at higher concentration.
Synthesis of Titania Nanostructures and their Application as Catalyst Supports for Hydrogenation and Oxidation Reactions
Authors: Sikhwivhilu Lucky Mashudu , Ray Suprakas Sinha , Coville Neil John
Published: March 2009

Nanomaterials are of great importance for their versatile applications in gas sensors,
solar cells and photocatalysis due to their unique optical, electrical and catalytic properties. Titania
derived nanotubular and nanospherical particles with a titanate structure were synthesized using a
hydrothermal procedure in the presence of very concentrated solutions of KOH and NaOH
respectively. Both nanostructures were found to exhibit relatively large specific surface areas, i.e.
280 and 303 m2/g for materials treated in NaOH and KOH respectively. The morphological and
structural properties were characterised by TEM, SEM, Raman spectroscopy and XRD.
Magnetic Anisotropy of Co Films Annealed by Laser Pulses
Authors: Kisielewski J. , Postava Kamil , Sveklo I. , Nedzved A. , Trzciński P. , Maziewski Andrzej , Szymański B. , Urbaniak M. , Stobiecki Feliks
Published: March 2009

The magnetic properties of an ultrathin cobalt film were modified by a focused
femtosecond pulsed laser beam. The Co wedge, with a thickness ranging from 0 to 2 nm,
sandwiched by Au films was prepared using ultra-high vacuum magnetron sputtering on a mica
substrate. The modifications of the laser induced magnetic anisotropy were investigated using
magneto-optic Kerr microscopy and MFM/AFM techniques. The laser induces: (i) local
reorientation of magnetization from an in-plane to a perpendicular state and (ii) an increase of the
coercivity field. A corresponding increase of the perpendicular magnetic anisotropy is discussed
considering an improvement of the Co/Au interfaces.
Flatness Based Control of Inductive Heating of X210CrW12 into the Semi Solid State
Authors: Gasper Rainer , Schönbohm Alexander , Enning Manfred , Abel Dirk
Published: March 2009

The inductive heating of the feedstock material is a very important step in the processing
of semi solid metals. On the one hand, the billet has to be heated as fast as possible to the target
temperature. On the other hand, it must be guaranteed that the outer area does not begin to melt
prematurely. Also, at the end of the heating the billet should have an uniform temperature
distribution in order to obtain good forming results. A flatness based control will be presented to
calculate the induced power over time trajectory from a desired trajectory for the temperature in the
middle of the billet. The temperature trajectory has to be chosen so that the billet has the desired
temperature behaviour. Experimental results will be shown for the flatness based inductive heating
of X210CrW12 just below the semi solid state.
Rheocasting of Al-Cu Alloy A201 with Different Silver Contents
Authors: Masuku E.P. , Govender Gonasagren , Ivanchev L. , Möller Heinrich
Published: March 2009

Rheocasting of alloys A206 and A201 was investigated in this study. Conical bars with
different silver contents were produced using CSIR rheoprocess technology, together with high
pressure die casting. The results showed that addition of Ag to alloy A206 increased the mechanical
properties of the alloy. However, the addition of Ag also resulted in Cu-rich phases to precipitate at
the grain boundaries of the as-cast material. The solution treatment used in this study was unable to
dissolve all of this phase, especially in the 1.12%Ag-containing alloy. This resulted in slightly
decreased mechanical properties compared to the 0.63%Ag-containing alloy. The T6 mechanical
properties (strength and elongation) obtained in this study for rheocast A206 and A201 are better
than those reported for permanent mould castings of alloy A206 and A201.
Development of Novel Hot Chamber Rheo-Diecasting Process
Authors: Lee Jin Kyu , Kim Shae K. , Lee Young Chul
Published: March 2009

Novel hot chamber rheo-diecasting process has been successfully developed. It requires no
additional processing equipment except commonly used hot chamber diecasting machine, no molten
metal control like grain refinement procedure and no additional cycling time to produce
slurry-on-demand. Additionally, it could lower molten metal temperature in a furnace. Process
concept of novel hot chamber rheo-diecasting is simply based on the paradigm shift from HOW to
WHERE for producing slurry-on-demand. This paper will demonstrate the possibility to achieve
slurry-on-demand by novel hot chamber rheo-diecasting and the advantages for 3Cs applications.
Robustness of a Thixoforming Production Line
Authors: Pierret Jean Christophe , Rassili Ahmed , Vaneetveld G. , Lecomte-Beckers Jacqueline , Bigot Régis
Published: March 2009

The development of the thixoforming process made great progress since its beginning.
But whereas thixoforming of aluminium and other low melting point alloys is now an industrial
reality, thixoforming of high melting point alloys, as steel, is still at the research level. High
temperature issues, die wearing and production rate are problems that must be solved and are more
and more investigated. This work is a study of the robustness of a complete thixoforming unit
dealing with steel. This flexible unit allows parts of various shapes be formed in conditions close to
industrial ones. The study focus on the heating strategy, heat exchanges between the slug and the
tool, the feeding and the cycle time. In this work, modelling has been used to simulate heating and
feeding. In parallel, experiments have been made to obtain the needed parameters, to validate the
modelling and to evaluate the capacities of such a line.
Rheoforging of Wrought Aluminum Alloys
Authors: Guo Hong Min , Yang Xiang Jie
Published: March 2009

Wrought aluminum alloys have wide variety applications in aerospace and automobile
industries, due to their superior properties compared to casting aluminum alloys. Rheoforging is a
modification of thixoforging, which starts directly from the liquid phase instead of reheating of a
billet. In the present process, suitable semi-solid slurries of wrought aluminum alloys are prepared by
the LSPSF (low superheat pouring with a shear field) rheocasting process within 25s. The effects of
processing conditions on the degree of spherical grain refinement in 2024, 6082 and 7075 alloys are
discussed. 2024 and 7075 alloys have been used in order to investigate rheoformability of high
performance aluminum alloy. Experimental results show that rheoforging based on LSPSF process
can produce relatively homogeneous microstructure throughout the cup-shaped component. However,
high solid fraction of semi-solid slurry promotes metal flow and results in solid/liquid segregation.
Subsequent optimized heat treatments raise significantly the mechanical properties. Future potentials
and challenges to be solved are discussed.
Rheological Characterization of a New Alloy for Thixoforming
Authors: Pola Annalisa , Roberti Roberto , Modigell Michael , Pape Lars
Published: March 2009

A new aluminum alloy (AlSi5Mg0.5Cu0.3Ag) for semisolid die-casting applications was
designed, starting from computational thermodynamics calculations by Computherm Database. The
goal was to obtain a combination of good castability and proper concentration of hardening elements
for strengthening precipitation treatment. The predicted thixotropic properties were verified by
measuring the microstructural conventional parameters, such as globule size and shape factor, and the
solidification range, by means of differential scanning calorimetry. To complete the characterization
of this new alloy and to evaluate its applicability in industrial production, the shear rate and
time-dependent flow behavior of the alloy in the semisolid state was studied in a Searle-type
rheometer. A future aim of the present research is to try to use rheology testing as the tool to optimize
the chemical composition, in order to design an alloy characterized by good mechanical performances
and easy processability. Considering the strong influence of the solid fraction content on semisolid
alloy viscosity, the rheology tests were interrupted after a certain time and the alloy was deeply
freezed using vaporized liquid nitrogen, in order to fix the microstructure and verify the correctness of
the thermodynamic simulation.
Couette Rheometry: Direct Analysis vs. Inverse Parameter Determination
Authors: Modigell Michael , Pape Lars , Vasilic Ksenija
Published: March 2009

The direct analysis and the inverse parameter fitting are methods for determination of
unknown material parameters in rheometry. In this paper the efficiency of the both methods is
examined on the case of a semi-solid alloy. The difference between the obtained material
parameters is studied and the necessity of inverse parameter fitting is discussed.
Functionally Gradient Materials via a Casting Process Involving Partial Solidification
Authors: Browne David J. , Scanlan M. , Bates A.
Published: March 2009

A novel technique for the production of functionally gradient materials, developed by the
authors, is presented. The process is known as the Cast-Decant-Cast or CDC process, and involves a
partial solidification step. This process takes expensive and time-consuming factors out of the
production of functionally gradient materials by enabling utilisation of standard foundry equipment,
and the process is carried out in a single multi-step casting operation.
The CDC process involves simultaneous but separate melting of two alloys of different composition
in order to produce a gradient in material properties. Details of the process are presented. It is shown
that the outcome depends on partial local remelting and alloy mixing, which results in a gradual
change or gradient between the first and second alloys in the as-cast condition, hence producing a
functionally gradient material.
The process has been adapted to conventional casting methods such as gravity casting and low
pressure casting. It is the method of decanting the first material from the mould that differentiates
the process variants. The decanting step for the low pressure method is controlled by pressure
application and release on the molten alloys within their respective, but separate, sealed holding
chambers. Decanting for the gravity casting method began as a physical inversion of the mould and
is now at the point of autodecanting through careful design of an innovative gating system.
The CDC process has been proven by means of metallographic study of microstructure to produce
functionally gradient materials. Adapting the CDC process to conventional casting methods has
made it a potentially commercially viable option for numerous applications. The results of recent
research on the process are presented in summary form, including multi-alloy experiments,
observations on the influence of timing and thermal control, and FGM manufacture using MMCs
and joining dissimilar metals.
A New Processing Route for As-Cast Thixotropic Steel
Authors: Walmag G. , Naveau P. , Rassili Ahmed , Sinnaeve M.
Published: March 2009

Up to now, no technology exists for producing as-cast thixotropic steel at the industrial
or pilot level. The existing processes need to reheat a billet that has been previously cast and
wrought on separate equipment. The new processing route, we are developing, will allow producing
as-cast steel (or high melting point alloy) with thixotropic properties.
CRM has developed and patented a continuous casting technology, which by using a specially
designed nozzle (HJN nozzle-hollow jet nozzle), allows to combine powder injection and a low
superheat. It has been proven by pilot and industrial trials that the combination of iron powder
injection and a low superheat leads to achieve a globular solidification structure in the core of a
continuously cast steel billet. Several industrial trials on continuous caster have been carried out
both with carbon and stainless steel but also on copper in order to modify the solidification structure
of these materials.
The application of this HJN technology is being studied in order to achieve a globular structure on
as-cast steel with the objective to obtain a thixotropic behaviour of the material after an adequate
reheating. Casting trials have been performed on CRM continuous casting pilot-line. Specifically
designed equipment has been built for use in a steel foundry. The influence of the solidification rate,
the superheat, the amount and the composition of the powder has been studied.
Fabrication of Semi-Solid Slurry for Steels and Their Rheo-Rolling Process
Authors: Song Ren Bo , Kang Yong Lin , Zhao Aimin
Published: March 2009

Semi-solid metal forming (SSM) has been recognized as a new forming technology, which
is different from the present metal forming methods. Basic research on SSM has been put into
operation and a number of SSM techniques have been widely applied in industry. In the application of
SSM technique, at present, it is mainly used to produce the low melting point alloys such as Al-base,
Zn-base and Mg-base alloys, but the high melting point alloys, for example steels as the most widely
useful metal are not extensively studied and applied. In the present work, the electromagnetic stirring
method was used to prepare semi-solid slurry of spring steel–60Si2Mn and stainless
steel–1Cr18Ni9Ti. At the same time, spring steel–60Si2Mn and stainless steel–1Cr18Ni9Ti were
directly rolled into thick strips in the semi-solid state (Rheo-rolling). It is aimed at studying the
microstructure and properties of the strips to establish the feasibility of rheo-rolling for the production
of the steel strips. According to the present research work, it has been shown that rheo-rolling process
combines the casting and hot rolling into a single step for near net-shape production, compared with
the conventional hot-rolled metallurgical process. Besides being such a cost-effective process,
rheo-rolling process possesses irregular crystal grains such as rosette-type primary crystals in the
microstructures because of sufficient agitation during solidification. The overall homogenization of
the macrostructures in the whole part of steel ingot can be achieved.
Semisolid Microstructural Evolution of Equal Channel Angular Extruded Mg-Al Alloy During Partial Remelting
Authors: Liang S.M. , Chen Rongshi , Han En-Hou
Published: March 2009

Using equal channel angular extrusion (ECAE) process, which combine the advantages of
grain refinement and induced strain, for preparing semisolid billets is a relatively new Strain Induced
Melt Activation(SIMA)method. This paper investigates the remelting and semisolid isothermal
holding behavior of Mg-9Al alloy after ECAE processing at 350°C. It has been found that 2 passes
ECAE-ed billets are qualified for obtaining spherical grains after remelting and isothermal holding
treatment. Increasing the ECAE process from 2 passes to 8 passes has no further significant effects on
the size and roundness of the solid particles at the semisolid state. The effects of temperature and
isothermal holding time on microstructural evolution have also been investigated. In addition, the
solid solution treatment before the ECAE processing affected greatly on microstructural evolution of
the alloy during ECAE processing and thus the following remelting and isothermal holding behavior.
The Mg17Al12 precipitates were uniformly decomposed from the saturated solid solution in the
solutionized samples during ECAE processing. The coalescence of grains together with the
self-blocking effect generated more entrapped liquid in the solutionized sample at semisolid state.
Moreover, the solid particles of solutionized samples have bigger size and grow faster, which are
detrimental to SSM processability.
Study of the Precision Forging of an Impeller by Numerical Simulation and Test Forming
Authors: Wang Wei Wei , Han Fei , Luo Shou Jing
Published: March 2009

In the present paper, the precision forging of an impeller was studied by means of
numerical simulation and test forming. Based on the structure and dimension of the impeller, the
combination structure was used in the forging die to obtain the extrusion deformation. The forming
processes were simulated with DEFORM-3D for different billet dimensions and processing
parameters. The parameters, which could ensure the forming quality of the impeller, were determined
by the calculations and analysis. The die structure and the billet dimensions were determined
according to the simulation results, and the forging die was designed and manufactured. The billet
with semi-solid microstructure was produced by means of the direct heating-isothermal treatment.
The forming was conduced in an YX-315F hydraulic press, and the precision forgings of the impeller
were produced successfully. Both of the simulation and the forming test show that the impeller
forging can be formed with the combination structure die and the extruding forming stale
satisfactorily. The ideal parameters to produce the precision forgings of the impeller are: billet
temperature at 625°C, die temperature at 450°C and punch speed at 20mm/s. Under these conditions,
forgings of the impeller can be produced with plump blades, smooth outer surface, and good flow
line. This can match the requirements of the precision forging of impellers.
Numerical Simulation of Mould Filling in Rheocasting Process of Semisolid A356 Aluminum Alloy
Authors: Bai Yue Long , Xu Jun , Mao Wei Min , Zhang Zhi Feng , Xu Hong
Published: March 2009

The apparent viscosity model of the semi-solid A356 aluminum alloy, based on fitting of
experimental data obtained by the Couette type viscometer, was developed in the paper. The
commercial package CastSoft6.0 coupled with the model was used to simulate the mould filling of the
semi-solid A356 aluminum alloy in the key-shaped component with iron cores. The simulation results
showed that the position of the iron cores has an important effect on the filling of the semisolid slurry,
and it is easy to obtain the completely filled key-shaped component when the iron cores were near to
the inlet. The filling tests verified that the simulation results have good agreement with the
experimental results. The fitting results indicated that the developed apparent viscosity model is
practical and feasible and it can be used to simulate the mould filling process of the semisolid A356
aluminum alloy slurry. Also the parameters were optimized and the optimum parameters are as
follows: the inject pressure is more than 15MPa, the inlet velocity is more than 1.73m/s and the
forming temperature is over 585 °C.
Study on Apparent Viscosity of Semi-Solid Alloys during Rheocasting
Authors: Liu Wen , Xing Shu Ming , Zhang Mi Lan
Published: March 2009

An analytical model of apparent viscosity was built up based on analysis of energy
dissipation during rheocasting. By study the evaluation law of microstructure analyzed with a
quantitative metallographic analysis system for semi-solid alloys, the variation law of apparent
viscosity with time has been obtained. The model was verified in the experiment of A356 alloys with
a coaxial double-bucket rheometer, and the results of simulated experiment and theoretical
calculation are in a good agreement.
Numerical Simulation of Semi-Solid Billet Preparation by Equal Channel Angular Extrusion
Authors: Zhang Xiao Hua , Zhang Yan Ying , Wu D.Z. , Luo Shou Jing
Published: March 2009

Equal channel angular extrusion (ECAE) is a technology of refining crystal grain. In this
paper, ECAE was introduced into the preparation of semi-solid billet and the extrusion process was
simulated using finite element method. The variation of stress (mean stress, max principle stress,
effective stress), the distribution of strain, the lattice change were obtained. The results show that
not only does the shear stress exist, but also the normal stress in the extrusion process; the stresses
in die inner corner of channel and outer corner of channel are not the same. In the inner corner,
besides the simple shear, there are compression, and in the outer corner, tension. The strain is
non-homogeneous and appears a graded distribution.
Improvement in Thixoforging of 7075 Aluminium Alloys at High Solid Fraction
Authors: Vaneetveld G. , Rassili Ahmed , Pierret Jean Christophe , Lecomte-Beckers Jacqueline
Published: March 2009

Thixoforging is a type of semi-solid metal processing at high solid fraction (0.5<fs<1).
7075 aluminium alloys have been used as a feedstock for thixoforging in order to investigate
thixoformability of a high performance aluminium alloy at high solid fraction. Higher solid fraction
of 7075 alloy is less sensitive to temperature, avoids metal splash at high speed and allows laminar
flow at high speed. Hot tool combined with lubricant tool coating are used to slow down the
solidification rate of the high solid fraction metal by decreasing thermal exchanges with the tool.
Improved thermal and forming parameters [1-2] will be applied to produce an automotive
component by thixoforging and mechanical properties have been measured from tensile samples.
High mechanical properties are obtained after T6 thermal treatment.
Microstructure and Mechanical Properties of Rheo-Extruded AZ31 Mg Alloy
Authors: Xu Jun , Zhang Shao Ming , Yang Bi Cheng , Shi Li Kai , Fan Z.
Published: March 2009

A new rheo-extrusion technique has been developed to produce extruded profiles. The
AZ31 slurry is fabricated by a twin-screw mechanism, and has spheroidal solid particles with a
grain size of about 50 to 80μm. The slurry was introduced into an extrusion container with an inner
diameter of 95mm, and then squeezed to a billet before extruding into a round bar with a diameter
of 22mm using a 500kN extrusion machine. It is found that the new technique has a lower
deformation resistance than that of the conventionally hot extrusion technique in the same extrusion
velocity. The microstructure and mechanical properties of the rheo-extruded bars were examined in
detail. The results illustrated that grains of the bar were very fine with the average grain size about
2.3μm，and the mechanical properties were improved substantially compared with those of the
same alloy produced by the conventional hot extrusion.
Fatigue Behavior of Semi-Solid Cast Aluminum: A Critical Review
Authors: Brochu Myriam , Verreman Yves , Ajersch Frank , Bucher Laurent
Published: March 2009

Aluminum alloys are increasingly used in automotive and aeronautic applications to
produce high performance, lightweight parts. Among the reasons for this, is the emergence of high
integrity processes (HIP), which widens the field of application for cast aluminum alloys. In fact,
metallurgical quality and consistency that characterize components produced by HIP are necessary
for critical safety components. In addition to attaining maximum strength, critical safety
components need to be ductile and resistant to cyclic loading. According to the North American Die
Casting Association, rheocasting is a high integrity process capable of producing parts with fewer
defects than conventional casting process. Rheocast components are known to have better
mechanical properties than permanent mold castings. Moreover, they can be heat-treated which is
impractical in the case of classical die cast components. However, the fatigue behavior of rheocast
aluminum alloys has been investigated since about 2000 and few results have been published on
this subject. This paper reviews the studies of fatigue behavior of aluminum semi-solid cast
components. Published experimental results on high cycle fatigue resistance (S-N diagrams), long
crack propagation, crack closure effects and short crack particularities are presented.
Effects of Thixoforming Defects on the Stress-Strain Curves of Aluminum Structural Parts for Automobile
Authors: Lee Sang Yong , Choi Byung Hyung
Published: March 2009

The effects of thixoforming defects on the stress-strain curves of aluminum structural part
were quantitatively investigated. The A357-MHD billet was thixoformed to manufacture a shock
tower part of a small electric vehicle. All tensile specimens were machined from only a shock tower
product to minimize the effects of different processing conditions. Tensile tests were performed under
the almost same conditions. The fraction of solid and liquid phase, the sizes and area fractions of
defects in the specimens were measured and analyzed by an image analyzing program using OM and
SEM micrograph. The fracture strain values of the stress-strain curves were greatly affected by
amount of defects. However, the analyses with defects existed in the area of gauge length did not
show a clear explanation about the relation with the fracture strain values. The measurements of
defects in the fractured surface represented more plausible results about the correlation of forming
defects and fracture strains.
Anodizing of A356 T6 Alloys Obtained by Sub-Liquidus Casting
Authors: Forn Antonio , Espinosa Isabel , Baile Maite T. , Rupérez Elisa
Published: March 2009

Semi solid processing reduces porosity and amount of trapped gas and it allows heat
treatment T6 that improves a hard anodized oxide layer. The aim of this work is to show the
anodizing possibility of A356 T6 components conformed by Sub-liquidus Casting (SLC) to improve
wear and corrosion resistance. This work compares the anodizing effect on tribological properties
and corrosion resistance between components obtained by A6061 T6 extruded alloys and from
A356 T6 produced by SLC. The effect of rounded silicon crystals on the coating formation and the
fracture produced during the coating growth are described.
Modeling of Inclined Cooling Plate Semisolid Processing by Model Alloy
Authors: Mehrara H. , Nili-Ahmadabadi Mahmoud , Heidarian B. , Ashouri S. , Ghiasinejad J.
Published: March 2009

Continual improvement of product quality has been a long challenge to Semi-Solid Metal
(SSM) technology. By conventional semi-solid processes, this might be attained at the expense of
economical production. The advent of Inclined Cooling Plate (ICP) process has already realized the
development of non-dendritic SSM while satisfying qualitative, quantitative and economical
requirements collectively. In spite of its potential advantages, functional mechanisms of this process
are not yet clearly understood that makes its optimal utilization obscured.
Basically, such understanding needs a picture of the process. As the first step, this picture is pursued
through physical modeling of the ICP process i.e. direct observation of an analog system by virtue
of transparent character of a model alloy (succinonitrile-acetone). Based on this phenomenological
model, a picture of the process is presented as follows: flowing molten alloy down ICP, multiple
regions form typically on the plate i.e. a chilled layer at the vicinity of the plate surface, a two-phase
mushy zone on the chilled layer and ambient liquid far from the plate surface. In this process,
interaction of the liquid forced-flow with mushy zone separates solid particles from the stationary
mush on the plate resulting in a two-phase mixture which is responsible for the formation of slurry
i.e. SSM.
Diagnostics of Scoring in Gears
Authors: Mirota Kryspin , Tomaszewski Jerzy , Rysiński Jacek
Published: March 2009

In the paper, the scoring phenomenon appearing on the surfaces of meshing teeth and the
conditions of its initiation are presented. The methodology of detection of this phenomenon is
proposed. Based on the formulated methodology, it is possible to determine the condition of a gear
by means of the reliability function.
Control of a Symmetrical Dual-Drive Gantry System Using Energetic Macroscopic Representation
Authors: Kestelyn Xavier , Gomand J. , Bouscayrol Alain , Barre P.J.
Published: March 2009

Dual-drive gantry systems are commonly used in many industrial applications. However,
as few papers are available in the literature, this kind of system is difficult to broach. Based on an
energetic approach so-called Energetic Macroscopic Representation (EMR), this paper presents a
graphical modelling based on lumped-parameters. The initial drive is decomposed into a set of
decoupled fictitious systems using a mathematical transformation. Since the modelling respects the
integral causality, inversion-based controls are thus deduced. More generally, this approach
proposes a way to analyze and deduce models and controls of multi-drive mechatronic systems.
Infrared Reflective Coatings for Window Glazing
Authors: Mohelníková Jitka
Published: March 2009

Glasses reflective in the spectral range of long-wave infrared radiation operate as heat
mirrors. These glasses have found wide applications in architecture. Special thin film coatings on
glass panes reflect long wave infrared radiation back to building interiors. The reflective thin films
limit absorption of infrared radiation within the glass pane and reduce radiation heat losses of
glazings. Heat losses of windows could be significantly limited with the coated glasses which are
called low-emissivity glazings. The study of materials convenient for infrared reflective coatings,
the optimal composition of thin films and their thicknesses is the main topic of the presented paper.
The study is based on measurements of spectral characteristics of selected glasses and computer
simulations of the thin film composition for applications of window infrared reflective coatings.
Modeling of Trainer's Electric Drive Control
Authors: Brazdeikis Liudas , Rėklaitienė Diana
Published: March 2009

The marches in mechatronic science and engeenering enable us to create and produce
high quality progammable sport and rehabilitation equipment. In study presented we analyze
modeling of trainer’s direct current drive control, which is designed to control realization with
programmable microcontroller. There we introduce block scheme of the drive’s model, working in
isokinetic and isotonic mode in the training equipment, and the main mathematical dependences.
Executing drives work simulation according to this model we have chosen optimal rates. Here we
present the samples of characteristics which were got by simulating.
"Magnetoactivated" Elastomer: An Alternative to Electroactive Polymer
Authors: Razouk Yousef , Duhayon Eric , Nogarede Bertrand
Published: March 2009

This paper deals with the development of a new type of composites called
"magnetoactivated" polymers and the exploration of some of their potential applications.
"Magnetoactivated" polymers consist of small embedding (micron-sized) magnetic particles in a
high elastic silicon matrix to render it magnetically active and at the same time mechanically strong.
The experimental characterizations obtained (magnetic permeability and Young modulus) were
systematically compared with the values resulting from the modeling of this material.The elastic
properties of our "magnetoactivated" silicon motive us to use them as pump membranes, the
evolution of the displacement of the pump membrane with the applied magnetic field were verified
in ANSYS and experimentally for various contents of iron particles in the silicon matrix.
The Characterization of WC-Co Based Materials Boronized within Molten Salt Bath
Authors: Köksal Sakıp
Published: March 2009

Coated WC-Co based cutting tool materials are widely used in machining applications.
However some of the coating techniques, such as physical vapor deposition (PVD), involve only the
physical deposition of coating layers which are prone to bulk delamination in some applications.
Therefore functionally graded microstructure through diffusion is an efficient and widely used
methods to improve the performance of coated WC-Co tools. In this work ISO P25, WC-Co based
inserts were subjected to a thermochemical diffusion treatment by boronizing in a molten salt bath.
The process was performed at 900, 1000, and 1100 °C for 1, 2 and 4 h. SEM, X-ray, EDS and
microhardness analysis were performed on the samples. It was found that boron containing hard
phases of W
2
B
5
, CoB, W
2
CoB
2
and WCoB were formed within the boronized region, occupying the
grain boundary areas. An average microhardness value of 3600 HK
0.01
was measured in the near
surface region which is substantially higher than the value of 1418 HK
0.01
representing the inner
sections of the material.
Fluoride Release from Composite Materials for Dental Fillings
Authors: Mystkowska Joanna
Published: March 2009

Fluoride release from composite materials for dental fillings depending on the type of
powder filler and dynamical loading is the main problem considered in the paper. The fillers used
for research were fluoridated glass (based on Ba-Sr-Al-P-Na-silicate glass), ytterbium fluoride
(YbF3) as a fluoride source and nanosilica. In order to estimate the influence of the usage loading
value on fluoride release from analyzed samples, the wear tests were carried out by means of
special tribotester in presence of phosphate buffer as a lubricant. After friction processes the
fluoride release tests were performed in phosphate buffer using direct potentiometry method with
fluoride selective electrode. The fluoride emission was analyzed on the basis of: 1) type and amount
of fillers powder, 2) using loading. Surface roughness was also investigated. The surface of each
composite was analyzed by means of SEM.
The Method of Complex Worthiness Assessment of an Engineering Object in the Process of its Use and Service
Authors: Lindstedt Paweł
Published: March 2009

A focus of the paper is concerned with the issue that optimal actions of regulation,
diagnostics and reliability tests of technical objects are required from the maintenance staff
involved in their use and servicing, and on the other hand, that they are performed independently
and autonomously in the current maintenance practice instead of being accomplished in a strictly
coordinated and complex way. It was noticed that only one and common information on the object
exists and provides a solid basis for coordination of the regulation, diagnostics and reliability tests.
This information can be applied many times for solving various problems no matter if they concern
regulation, diagnostics or reliability. Next, this paper presents an original approach of conversion of
the considered information into explicit time-and-space determined “number of threshold value
overshoots” of signals related to the object and its environment as well as theoretical foundations
(based on various configurations of the state equation) for conversion of the considered piece of
information, expressed by the aforementioned “numbers”, into the parameters of the object ability
condition (i.e., its technical condition, adjustment and reliability). The theses of the presented
complex method for the assessment of technical object ability were subjected to long-term
verification with positive result in the study of the Allison 250 engine bearing system.
Modeling of Beam as Control Plane for a Vibration Control System
Authors: Gosiewski Zdzisław , Koszewnik Andrzej Piotr
Published: March 2009

An active vibration damping system with the use of piezoelements fixed to the structure
is presented in the paper. The optimal location of the piezo-stripes on the structure is calculated for
given cost functions. Coefficient correlations between control forces, strains, mode shapes,
frequency changes, modal masses and modal stiffness are analyzed in order to find simpler method
for calculation of the quasi-optimal localization of piezo-sensors and piezo-actuators. Reduced
model of the open-loop system was identified and the simulations were carried out in order to find
the best controller to reduce the amplitude of vibrations. The correctness of the selection of the
controller was verified and investigated experimentally.
Weak Interactions between Objects Used as New Diagnostic Signals in the Detection of Pipeline Leakages
Authors: Ostapkowicz Paweł
Published: March 2009

The article is concerned with detection of leakages in pipelines. The new method of
improving diagnostic susceptibility of pipelines has been proposed. The essence of this new method
is the acquisition of new diagnostic information (i.e. signals). In contrast to the standard signals
(measurement of pressure, flow rate, temperature) used up to day, this information is the
measurable signals of weak interactions between objects, resulting from the work of testing objects
(correctors) joined to tested object (pipeline). The method has been verified experimentally. On the
basis of the results of the experimental research it has been demonstrated that due to these new
diagnostic signals it is possible to improve the diagnostic susceptibility of pipelines, and, thus
increase the efficiency of leakages detection conducted by means of the methods used hitherto.
Developing a High Volume Manufacturing Wet Clean Process to Remove BF2 Implant Induced Molybdenum Contamination
Authors: Sehgal Akshey , Huang Hsin Hsiung , Ramdani Jamal , Klatt Jeffrey , Printy Craig , Ruby Scott , Thibeault Todd
Published: March 2009

This work details the investigation of potential problems in Complimentary BiCMOS technology, especially PNP transistors arrays. Optical examination of the wafer revealed defects in the P Buried Layer (PBL) areas of the die. Electrical testing correlated these PBL defects to PNP array current leakage. As the PBL module is completed very early on in the process, we devised a shortloop (SL) to reproduce these defects and identify the root cause of current leakage.
Single Wafer Ozone-Based Processing for Effective Edge Fluoropolymer Cleaning
Authors: Niccoli John , Cogrono Matt , Eastlack Michelle , McCane Dave , Carlson Craig , Young Erik , Chapek Dave
Published: March 2009

The interaction between photo resist and highly polymerizing dry etch chemistries results in the deposition of fluoropolymers on the bevel and edge of silicon wafers. These polymers are inert to most aqueous processing chemicals, but exposure to HF lifts these polymers off the bevel. This results in migration of defects to the face of the wafers. The defects are generally found within 50mm from the edge of the wafer.
Impacts of Ionization Potentials and Megasonic Dispersion
Authors: Franklin Cole
Published: March 2009

It has been shown that megasonics can accelerate strip processes such as doped and plasma treated photoresist [1]. However, applied megasonic energy can also damage sensitive semiconductor devices. It was shown that adding a solvent such as IPA or lowering the temperature helps to control cavitation in semi-aqueous fluids [2]. Sonochemical reactions have been observed in various industries, however, there are no published observations in semiconductor cleaning. Ions may form in megasonic driven bubble collapse impacted by the characteristics of a gas or liquid that enters the bubble from the bulk liquid. Lower ionization potential gases or liquids may form ions earlier in the bubble collapse, so as to use up some of the total available energy through sonochemical reactions and possibly reducing the cavitations implosive energy. Here, tests are conducted to vary the liquid and gas type based on ionization potential to look into the impact this would have on cleaning and damage. It is shown that lower ionization or liquid additives lower the device damage.
Influence of Wet Cleaning on Tungsten Deposited with Different Techniques
Authors: Votta Annamaria , Pipia Francesco , Borsari S. , Ravizza Enrica , Elbaz Alice C. , Alessandri Mauro , Bellandi Enrico , Bresolin C.
Published: March 2009

Tungsten is a metal widely used for interconnections. As a consequence of more stringent requirements in terms of aspect ratio deriving from device shrinking, the filling of W plugs is becoming more and more critical and new deposition techniques need to be employed to properly fill contacts and trenches. For example ALD nucleation layers need to be coupled to CVD deposition. Since physical-chemical properties of W are heavily influenced by deposition techniques, the effect of wet cleanings on different kind of W needs to be fully understood in order to avoid any kind of W corrosion or recession during wet cleaning with W exposed. In this paper the effect of several chemicals commonly used in BEOL wet cleanings for polymer removal, has been investigated on W films deriving from both CVD and ALD deposition techniques.