bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Technique for the Rapid Manufacturing of Direct-Oxidation Anodes for SOFC's
Authors: Ben-Oved Nir , Kesler Olivera
Published: March 2009

A new rapid manufacturing technique for the production of SOFC anodes for direct oxidation of
hydrocarbon fuels has been demonstrated. Composite anodes with doped ceria as catalyst and ion
conductor and copper as electronic conductor have been fabricated by plasma spraying in air. The
process, which can be readily automated and scaled up for mass production, provides a rapid
method to produce anodes with mixtures of low and high melting temperature components in
several minutes. These anodes previously have required complex multi-step, multi-day processes
involving infiltration of sintered pre-forms. This work demonstrates the feasibility of using plasma
spray processing to manufacture composite Cu-SDC coatings for application in direct-oxidation
SOFC anodes.
Effect of Water Vapor in Air on the Oxidation Behavior of Ferritic Stainless Steels for SOFC Interconnects
Authors: Chung J.H. , Huh Joo Youl , Jun Jae Ho , Kim D.H. , Jun Joong Hwan
Published: March 2009

In the attempt to develop materials for interconnects of planar-type solid oxide fuel cells
(SOFC), the oxidation behavior and scale electrical properties of four, commercially available,
ferritic stainless steels were investigated by oxidizing at 800°C for times up to 900 h in the dry and
wet air environments. The growth kinetics of oxide scales were significantly deviated from the
parabolic growth law, exhibiting the temporal growth exponent being much less than 0.5. Titanium
addition in ferrite stainless steels was detrimental to oxidation resistance since its fast out-diffusion
onto the scale surface enhanced the scale growth. For the alloys without Ti contents, the presence of
water vapor in the oxidizing environment enhanced the scale growth rate, but it resulted in a drastic,
microstructural change of oxide scale that consisted of Cr2MnO4 spinel and Cr2O3, which in turn
lowered the area specific resistance (ASR) and the apparent activation energy for conduction.
Preparation of Fast Proton-Conducting Phosphate Glass-Derived Hydrogels and their Electrochemical Properties
Authors: Akamatsu T. , Kasuga Toshihiro , Nogami Masayuki
Published: March 2009

When fine-sized 45ZnO·55P2O5 glass powders were mixed with water, hydration
immediately occurred, resulting in the formation of a viscous hydrogel. 31P MAS-NMR spectra
showed that the hydrogel contains orthophosphates and long polyphosphates. 45ZnO·55P2O5
glass-derived hydrogel (45ZP gel) showed high conductivities of 9.9 mS/cm at 30 °C. The
conductivities were related to the proton amount in the hydrogel. The electric double-layer capacitor
(EDC) cell for the 45ZP gel showed no oxidation-reduction processes in the range of 0~1 V and the
specific capacities of 2.40 F/g. The possibility as an EDC electrolyte may be related to the
conductivities of the hydrogels.
Analysis of Complex Heat Flow Phenomena with Friction Stir Welding Using 3D-Analytical Model
Authors: Rajesh S.R. , Bang Han Sur , Kim Heung Ju , Bang Hee Seon
Published: March 2009

Friction stir welding is being attracted and developed as an efficient joining method in
the manufacturing field of Automobile, Aerospace and Ship building industries. As the FSW
develops, more scientific research work investigations in this field have also been increased. Recent
studies in FSW have revealed that both heat and metal flow characteristics have a non-symmetric
complex nature about the tool axis. But until now there is no efficient 3D- heat flow model to be
comparable with the experimentally measured values. The body of the work covered FSW of
Al6061 and its thermal distribution based on a nonsymmetrical analytical model for the heat input
in to the matrix of Al plates from FSW tool due to the effect of combined translation and rotational
motion of the tool pin and shoulder. Finally the 3D- finite element heat transfer analysis program
has been used to plot the heat distribution at the Friction Stir Welded joint in Al 6061 plate. The
work concludes that the heat distribution result obtained from FE analysis has a reasonable
agreement with the experimentally measured values.
On Mg-Al-Zn Intermetallic Alloys Made by Friction Stir Processing Containing Quasi-Crystals or Amorphous Phases
Authors: Chang C.I. , Lee C.J. , Chuang C.H. , Pei H.R. , Huang J.C.
Published: March 2009

The characterizations on the microstructural and mechanical properties of the Mg-Al-Zn
multi-element intermetallic alloys fabricated by friction stir processing (FSP) are presented. The
composites of the alloys vary within Mg35-70Al5-25Zn25-45. The maximum working temperature can
reach 550oC. The current process applies the FSP on vertically stacked foils of various portions of
Mg, Al and Zn, 99.9% in purity and 0.2 to 1 mm in thickness. In order to homogenize the alloy
composition, three or more FSP passes in opposite directions are applied. Depending on the relative
contents of Mg, Al and Zn, numerous intermetallic compound phases are induced. The resulting
intermetallic alloys exhibit high hardness up to 350 Hv.
Dissimilar Metal Joining of Magnesium Alloy to Steel by FSW
Authors: Abe Y. , Watanabe Takehiko , Tanabe H. , Kagiya K.
Published: March 2009

Authors tried to butt-weld a mild steel plate to a magnesium alloy plate by the solid
state welding using a rotating pin. This study investigated the effects of a pin rotating speed, the
position for the pin axis to be plunged (pin offset) on the strength and the microstructure of the joint.
The main results obtained are as follows. Butt-welding of a steel plate to a magnesium alloy plate
was easily and successfully achieved. The maximum tensile strength of a joint reached about 70%
of the magnesium base metal tensile strength and the fracture path was along the joint interface.
When a pin rotating speed was slow, some defects appeared in the magnesium matrix due to the
insufficient plasticization of the magnesium. The joint strength increased with the pin rotating speed.
This seems to be because the plasticization of the magnesium was increased and the pressure for
pushing the plasticized magnesium onto an activated faying surface of the steel increased. However,
the excessive increase of the pin rotating speed caused the ignition of the magnesium, resulting in
the decrease of a joint strength. At the pin offset of 0.1mm toward steel, steel fragments scattered in
the magnesium matrix in the form of a small piece that had no influence to the joint strength. By
contrast, larger offsets over 0.2mm produced the steel fragment continuous and parallel to the weld
interface in the magnesium matrix, and the joint strength decreased.
Sound Absorption Behavior of Porous Al Produced by Spacer Method
Authors: Kuromura Tetsumune , Hakamada Masataka , Chen Y. , Kusuda Hiromu , Mabuchi Mamoru
Published: March 2009

Porous Al specimens with a pore size range from 212-300 to 610-700 μm, a porosity from
85 to 95% and a specimen thickness from 2 to 20 mm were produced by the spacer method, and their
sound absorption capacity was investigated. For these specimens, sound absorption coefficient
increased with increasing porosity. On the other hand, sound absorption coefficient varied
inconsistently with the variation of pore sizes. The latter may be attributed to variation of aperture
sizes of each specimen because the porous Al specimens with differerent pore sizes produced by the
spacer method should have different aperture sizes. Sound absorption coefficient increased at the
frequency below 2000 Hz with increasing specimen thickness.
Fabrication Methods and Properties of Open and Closed Cell Foams
Authors: Konstantinidis I.Ch. , Papadopoulos D.P. , Gavaises M. , Tsipas D.N.
Published: March 2009

In this paper we present some simple methods for the fabrication of closed and open cell Al
metal foams. The closed cell Al metal foams were fabricated using liquid metallurgy. Their
microstructure and morphological characteristics were studied using optical and electron microscopy
techniques. The mechanical properties and their relationship to microstructure were established. A
three dimensional model was developed relating the cell geometry to the mechanical behavior of Al
closed cell foam material. The open cell Al foams were fabricated using sodium chloride powder
sinters and liquid Al metal infiltration techniques. The potential of using these cellular structures in
various systems is discussed.
Longitudinal Seam Failure in Extruded AZ31 Alloy
Authors: Hiscocks Jessica , Jiang Lan , Jonas John J.
Published: March 2009

Research is currently being conducted on the feasibility of hydroforming extruded
magnesium tubes to integrate multiple parts into a single hydroformed section. Among other
applications, such sections would reduce the weight of both cars and planes, particularly when used
in the vehicle frame. This would lead to either reduced fuel costs, or the ability to carry an
increased payload. Magnesium generally has limited ductility, which in the case of the current
extruded tubes is even further reduced at the extrusion seams. These are locations where the
material flow separates and rejoins during extrusion and are unavoidable when a hollow profile die
is used. When the tubes were stressed in a circumferential direction, tube ruptures consistently
occurred along the extrusion seams of the tubes. This led to the current project, an inquiry into the
exact cause of failure at these locations. The creation of irregularities at the seams, such as
precipitate dispersions, local texture changes, grain size changes and entrained material, is
discussed. These irregularities are considered together with their roles in producing the failures.
The results are summarized and the most fruitful directions for future work are outlined.
HRTEM Observation of the Age Hardening Precipitates in Mg-15wt%Gd-Zr Alloy
Authors: Matsuno Toshiyuki , Kawabata Tokimasa , Matsuda Kenji , Kamado Shigeharu , Kojima Yo , Ikeno Susumu
Published: March 2009

The TEM observation was performed to investigate the precipitation hardening in
Mg-Gd-Zr alloy. Both the β’ and the β” phase coexist in the specimen aged at 473K for 16h. In the
specimen aged at 523K, the β’ phase which has base centered orthorhombic (bco) structure was
observed at early stage during aging. The β’ phase has a globular shape and four atomic layer
periodicity in the [1100]Mg. The β’ phase grew with increasing aging time mainly along the [0001]Mg
and the [1100]Mg.
Corrosion Behavior of Die-Cast and Thixocast AXJ530 Magnesium Alloy in Chloride Medium
Authors: Amira Sofiene , Shehata M. , Dubé Dominique , Tremblay R. , Ghali Edward
Published: March 2009

The corrosion behavior of AXJ530 magnesium alloy in 3.5% NaCl solution at 25°C and pH 7.25
has been studied. Die-cast and thixocast specimens were tested using constant immersion technique,
potentiodynamic polarization measurements and electrochemical noise analysis. The microstructure
of cast specimens and their surface aspect after corrosion tests were analysed and compared. The
results show that thixocast specimens have the best corrosion resistance. Their superior corrosion
resistance can be attributed mainly to the presence of large pre-existing α-Mg grains.
Effect of Chrome-Free Chemical Conversion Coating on Corrosion Behavior of Magnesium Alloy AZ91D
Authors: Bai Li Qun , Li Di , Guo Bao Lan , Guo Min
Published: March 2009

The different chrome-free chemical conversion coatings were prepared on AZ91D
magnesium alloy and SEM was used to observe the surface. The corrosion behaviors of die-casting
AZ91D magnesium alloy with different coating in chloride environment were investigated by
hydrogen gas evolution in immersion test, salt spray test and electrochemical measurement. The
results showed that the corrosion resistance of magnesium alloy treated with two-step chemical
conversion and sealing was the highest and was comparable with that of chromating, and followed
by two-step chemical conversion treatment without sealing. The one-step chemical conversion
treatment had the lowest corrosion resistance. Polarization and EIS characteristics in 5% NaCl
solution depended on the type of surface treatment and correlated well with the order of corrosion
resistance. Contrasted with one-step chemical conversion coating, the coating of two-step chemical
conversion with sealing on magnesium alloy had more excellent corrosion resistance because the |Z|
increased, the corrosion area was decreased and the time of the first pitting occurrence was
prolonged. It is expected that this experiment can provide a foundation for designing more super
chemical conversion coating to replacing the chromate conversion.
Influence of SO2 Concentration on Initial Corrosion of Aluminum in Marine Atmosphere
Authors: Han De Sheng , Li Di , Zheng Tian Liang
Published: March 2009

Influence of SO2 concentration on initial corrosion of aluminum was
studied in simulated marine atmosphere. Variation of initial corrosion morphology,
relation between weight gain and time in the course of initial corrosion, corrosion
speed (token with maximum pitting depth and weight gain) were analyzed and
discussed. Primary results is list below:
In marine atmosphere, SO2 sedimentation above 0.1 mg/100cm2 can accelerate
Al pitting with low Cl- sedimentation. Both corrosion weight gain and pitting depth
increase obviously. For pitting surface of LY12 with SO2 and Cl- sedimentation,
corrosion potential change little, Nyquist Graph was single arc of capacitance resist
with retractile real part, Rr can’t reflect corrosion degree.
Production of Silver Coated Copper Powders by Electroless Plating Method
Authors: Hai Hoang Tri , Ahn Jong Gwan , Kim Dong Jin , Lee Jae Ryeong , Jang Y.N. , Chung Hun Saeng , Kim Chong Oh
Published: March 2009

Copper powders with very dense, uniform silver coating layer were prepared by electroless
plating method in aqueous system at room temperature. Silver-copper composite powders were
obtained by strictly controlling the activation and complexing process variables such as
NH4OH/(NH4)2SO4 molar ratio, tartrate concentration, and feeding rate of silver ion solution. The
mechanism of composite powders formation and their characteristics were discussed. It is noted that
completely cleansing the oxide layers and protecting the copper particles surface from hydrolysis
are key factors to obtain high quality Ag-Cu composite powders.
Influence of Cooling Rate on the Size of the Precipitates and Thermal Characteristic of Al-Si Cast Alloys
Authors: Maniara Rafał , Dobrzański Leszek Adam , Sokolowski Jerry , Kasprzak Wojciech , Kierkus Witold T.
Published: March 2009

In this work effect of cooling rate on the size of the grains, SDAS, β phases and thermal
characteristic results of Al-Si cast alloys have been described. The solidification process was
studied using the cooling and crystallization curve at cooling rate ranging from 0,1 °Cs-1 up to
1 °Cs-1. The main observation made from this work was that when cooling rate is increased the
aluminum dendrites nucleation temperature and solid fraction at the dendrite coherency point
increases, which implies that mass feeding is extended. In addition to that, it was observed that
solidus temperature and size of the β phases decreases when cooling rate increases. Investigations
were showed, that the thermal modification could be quantitatively assessed by analysis of the
crystallization curve.
Deformation Characteristics of Epoxy Compounds for Semiconductor Integrated Circuits
Authors: Saiki Hiroyuki , Marumo Yasuo , Nishitake Hiroshi , Hazama Masahiro , Sakata Fuminori
Published: March 2009

Tensile tests of epoxy molding compounds were carried out using specimens composed of
epoxy molding compounds which are transfer molded and post cured. The mechanical characteristics
of the epoxy molding compounds change significantly due to changes in temperature and strain rate.
In addition, the effect of nonlinear viscosity is large in both elastic and plastic regions. The
characteristics of the visco-elastic-plastic behaviors of the epoxy molding compounds were examined.
The behavior characteristics of the epoxy molding compounds during loading and unloading were
shown in detail.
Microstructures of Rapidly Solidified Pb-Sb-Sn-Alloys
Authors: Schouwenaars Rafael , Romero J.I. , Jacobo Víctor H. , Ortiz Armando
Published: March 2009

Rapidly solidified industrially stripcast Pb-Sb-Sn triboalloys showed microstructures
typical for the eutectic decomposition of metallic glasses. Evidence was found of crystallisation
above the glass transition temperature and ageing at room temperature. The observation supports a
previous hypothesis by the authors on the wear properties of soft tribological alloys.
Board-Level Reliability of Pb-Free Surface Mounted Assemblies during Thermal Shock Testing
Authors: Kim Jong Woong , Chun Hyun Suk , Ha Sang Su , Chae Jong Hyuck , Joo Jin Ho , Shin Young Eui , Jung Seung Boo
Published: March 2009

Board-level reliability of conventional Sn-37Pb and Pb-free Sn-3.0Ag-0.5Cu solder joints
was evaluated using thermal shock testing. In the microstructural investigation of the solder joints,
the formation of Cu6Sn5 intermetallic compound (IMC) layer was observed between both solders and
Cu lead frame, but any crack or newly introduced defect cannot be found even after 2000 cycles of
thermal shocks. Shear test of the multi layer ceramic capacitor (MLCC) joints were also conducted to
investigate the effect of microstructural variations on the bonding strength of the solder joints. Shear
forces of the both solder joints decreased with increasing thermal shock cycles. The reason to the
decrease in shear force was discussed with fracture surfaces of the shear tested solder joints.
On the Physical Meaning of the Hall-Petch Constant
Authors: Luo Ji , Wang Zhi Rui
Published: March 2009

In order to solve the contradiction found in the Hall-Petch behavior in the ultra-finegrained-
and nano-grained- materials, reinvestigation of the physical meaning of Hall-Petch
constants has become necessary. The present work is hence attempted to theoretically construct the
Hall-Petch slope constant, KH-P. This was carried out based on the principle of image analysis and
previous internal energy approach. After analyzing several influencing factors on the KH-P, a model
was established with 95% accuracy in predicting the KH-P value. In other words, this model, for the
first time, has related the KH-P value to grain boundary surface energy,γ , shear modulus, G, and
lattice constant, a0, via
1/ 2
0 K β G(2a γ ) H P = − .
Microstructural Evolution and Recrystallization Behavior in Copper Multi-Directionally Forged at 77 K
Authors: Nakao Y. , Miura Hiromi , Sakai Taku
Published: March 2009

Microstructural evolution in pure copper during multi-directional forging (MDF) at
temperature of 77 K was studied. Flow stress during MDF at 77 K showed a monotonical increase
at all strain. Ultra fine (sub)grains of 0.15μm in diameter were evolved, which was accompanied
by deformation twinning, at strain of Σε = 2.4. In higher strain region, Σε = 6.0, lamellar-look
structure of twins extensively appeared. The lamellar spacing was 10-100nm. For comparison,
samples were also MDFed at 300 K. The flow stress curves showed an apparent steady state flow at
above strain of Σε =2.0, which implies occurrence of dynamic recovery. The evolved (sub)grain
size was 0.3 μm at high strain of Σε = 6.0. Therefore, grain refinement seems to take place more
easily by MDF at 77 K compared with that at 300 K due to effect of deformation twin.
Microstructures evolved under MDF at 77 K and 300 K showed different annealing behavior. Static
recrystallization started earlier and faster in the samples MDFed at 77K than those MDFed at 300K.
Bone Tissue Engineering: Natural Origination or Synthetic Polymeric Scaffolds?
Authors: Danti Serena , Lisanti Michele , Berrettini Stefano , Petrini Mario , Pietrabissa Andrea
Published: March 2009

The aim of this report was to investigate the behavior of human mesenchymal stem cells
(hMSCs) when cultured on different porous 3D scaffolds, having natural or synthetic origination.
Natural scaffolds were obtained by hand made processing of human bone tissue (allograft), because
its well known osteoconductive features, using different procedures to eliminate the donor cellular
phase. Cancellous bone was frozen, heated or demineralized before being loaded with hMSCs.
Among the variety of synthetic materials, biodegradable polymeric spongy matrices were chosen
and comparatively tested as scaffolds for hMSCs growth.
The Effect of Grain Size and Amount of β Phase on the Properties of Back-Torsion Working in 60/40 Brass
Authors: Matsumoto J. , Anada Hiroshi , Furui Mitsuaki
Published: March 2009

It was limited to 60/40 brass and the adjustment of grain size was performed, thereafter, it
was processed by one way torsion working and back-torsion working. The effect of both workings
on the work hardening and the surface roughness of 60/40 brass were investigated. The quenched
material has excellent surface roughness in comparison with the furnace-cooled material both after
and before workings. It seemed that a little difference in their grain size (15-55μm) affects the
restoration ratio of surface roughness. For the back-torsion worked material, as the grain size is
coarse, the amount of hardening increases. If the β phase ratio is more, it is easy to become
hardened. Inversely, if the β phase ratio is less, it obtains the maximum amount of hardening.
HRTEM Study of α-Phase in Cu-Zn-Si Alloy
Authors: Hamatani Daisuke , Matsuda Kenji , Kawabata Tokimasa , Uetani Yasuhiro , Ikeno Susumu
Published: March 2009

The α-phase in 60/40 brass added Si was investigated by transmission electron microscope (TEM)
in order to understand the relationship between the ability of hardening during annealing and phase
decomposition. The ability of hardening ( Δ HV), which is the value of difference between the
maximum hardness during annealing and the value of as-quenched sample, was obtained
measurement from the alloy. As a result, the Si-bearing alloy is higher in ΔHV than a base alloy
without Si. The α-phase in the Si-bearing alloy showed fringes in its TEM image like as stacking
faults, and extra reflected spots in its selected area diffraction pattern (SADP), which is
corresponding to the 9R structure. Streaks were also observed together with spots in its SADP.
Extra reflected spots and streaks in SADP became weak or disappeared when the annealing time
increased. After 600 ks annealing, SADP obtained from the α-phase could be indexed as FCC lattice.
Change in chemical composition of α-phase was also measured by the energy dispersive X-ray
spectroscopy (EDS).
Numerical Simulation of Microstructural Evolution in Isothermally-Aged Cu-Ni Based Alloys
Authors: Avila-Davila Erika O. , Melo-Maximo D.V. , Gutierrez-Mendez Carmen , Saucedo-Muñoz M.L. , Victoria-Hernández V.M.
Published: March 2009

The microstructure simulation of spinodal decomposition was carried out in the isothermally-aged
Cu-Ni and Cu-Ni-Fe and Cu-Ni-Cr alloys using the phase field method. The numerical simulation
was based on a solution of the Cahn-Hilliard partial differential equation by the finite difference
method. The calculated results were compared to those determined by atom-probe field ion
microscope analyses of the solution treated and aged alloys. Both the numerically simulated and
experimental results showed a good agreement for the concentration profiles and microstructure in
the aged Cu-Ni, Cu-Ni-Fe and Cu-Ni-Cr alloys. A very slow growth kinetics of phase
decomposition was observed to occur in the aged Cu-Ni alloys. The morphology of decomposed
phases consists of an irregular shape with no preferential alignment in any crystallographic
direction at the early stages of aging in all the aged alloys. In the case of the aged Cu-Ni-Fe alloy,
a further aging caused the change of initial morphology to an equiaxial shape of the decomposed
Ni-rich phase aligned in the elastically-softest crystallographic direction <100> of Cu-rich matrix.
The growth kinetics rates of phase decomposition in Cu-Ni-Fe and Cu-Ni-Cr alloys are
appreciably faster than that in Cu-Ni alloys.
Estimation of the System Free Energy of the Lath Martensite Phase in High Cr Ferritic Steels
Authors: Kunieda Tomonori , Akada Kensuke , Murata Yoshinori , Koyama Toshiyuki , Morinaga Masahiko
Published: March 2009

The system free energy was estimated for the martensite phase of an Fe-Cr-C ternary
alloy, 12Cr2W and 12Cr2W0.5Re steels. The system free energy of the martensite phase is defined
as, Gsys = G0 + Estr + Esurf , where G0 is the chemical free energy, Esurf is the interfacial energy for
the boundaries in the martensite microstructure, and Estr is the elastic strain energy due to the
dislocations in the martensite phase. From the experimental results on SEM/EBSD, the total
interfacial energies were estimated to be 0.83J/mol for the ternary alloy and 4.8J/mol for both
12Cr2W and 12Cr2W0.5Re steels in the as-quenched state. Also, the elastic strain energies were
estimated to be 7.1J/mol for the ternary alloy, 9.6J/mol for 12Cr2W steel and 9.8J/mol for
12Cr2W0.5Re steel in the as-quenched state. So, the system free energy was about 7.9J/mol for
ternary alloy. On the other hand, the system free energy was about 14.4J/mol for 12Cr2W steel and
14.6J/mol for 12Cr2W0.5Re steel. So, these microstructural energies operate as a driving force for
the microstructure evolution, e.g., recovery of dislocations and the coarsening of the sub-structures
such as martensite-packet, -block and -lath.
EBSD Phase Identification and Modeling of Precipitate Formation in HP Alloys
Authors: Laigo Johanne , Tancret Franck , Le Gall René , Furtado Jader
Published: March 2009

Heat-resistant steels of HP series (Fe-25Cr-35Ni) are used as reformer tubes in
petrochemical industries. Their composition includes Nb and Ti as strong carbide formers. In the ascast
condition, alloys exhibit an austenite matrix with intergranular MC, M23C6 and/or M7C3
eutectic carbides. During exposure at high temperature, phase transformations occur: chromium
carbides of M7C3 type transform into the more stable M23C6 type, intragranular M23C6 carbides
precipitate, and a silicide, the G-phase (Ni16Nb6Si7), forms due to the instability of MC carbides
(NbC). Thermodynamic simulation is of great help for understanding precipitate formation and
transformations. Thermo-Calc and Dictra are used to simulate the precipitation of carbides in the
austenite matrix during service. However, from an experimental point of view, M23C6 and M7C3 are
not easy to distinguish in bulk alloys. Indeed, backscattered scanning electron microscopy does not
bring any contrast between the two phases, and energy dispersive spectroscopy (EDS) analysis does
not lead to carbon content and consequently to the distinction between M23C6 and M7C3. With
transmission electron microscopy (TEM), sample preparation is difficult and the observed area is
extremely small. In the present work, HP alloys are investigated by electron backscatter diffraction
(EBSD) coupled to EDS. Carbides are identified on the basis of crystal structure, in the bulk, within
their microstructural context, and the experimental procedure is both simpler and cheaper than
TEM. Precipitates (M23C6, M7C3) could be identified by orientation mapping and single spot
analysis.
Hot Deformation Analysis of a 2 wt.-% Si Electrical Steel by Means of Torsion Tests
Authors: Rodriguez-Calvillo Pablo , Colás Rafael , Houbaert Yvan
Published: March 2009

Steels with high amounts of silicon are used in electrical applications due to their low
mangectoestriction, high electrical resistivity and reduced energy losses, but they exhibit poor
formability. A fundamental study of the workability of such materials using torsion testing may
help to understand and to optimise its production. Single deformation torsion tests were carried out
on a steel containing 2 wt.-% Si in a temperature range of 800 to 1100°C and strain rates in the
range of 0.01 to 2 s-1. A value of 299 kJ/mol was found for the apparent activation energy for hot
working after applying the hyperbolic-sine equation to the mean flow stress (MFS) values
computed from the test. Multiple deformation torsion tests under continuous cooling conditions
were carried out in the same temperature range at strain rates from 0.2 to 1 s-1, the strain per pass
and interpass time (determining the cooling rate) were varied. Different critical temperatures, which
are of importance for processing this alloy, can be calculated from the dependence of MFS with the
inverse absolute temperature; such a method was used to determine the temperature at which
recrystallisation stops (Tnr). It was found that this temperature depends on strain rate, pass strain and
interpass time. Results of the microstructure analysis of quenched samples are in good agreement
with the values of Tnr.
Preparation and Characterisation of New Titanium Based Alloys for Orthopaedic and Dental Applications
Authors: Nouri A. , Chen X.B. , Hodgson Peter , Wen Cui E
Published: March 2009

Various types of titanium alloys with high strength and low elastic modulus and, at the
same time, vanadium and aluminium free have been developed as surgical biomaterials in recent
years. Moreover, porous metals are promising hard tissue implants in orthopaedic and dentistry,
where they mimic the porous structure and the low elastic modulus of natural bone. In the present
study, new biocompatible Ti-based alloy foams with approximate relative densities of 0.4, in which
Sn and Nb were added as alloying metals, were synthesised through powder metallurgy method.
The new alloys were prepared by mechanical alloying and subsequently sintered at high
temperature using a vacuum furnace. The characteristics and the processability of the ball milled
powders and the new porous titanium-based alloys were characterised by X-ray diffraction, optical
microscopy and scanning electron microscopy .The mechanical properties of the new titanium
alloys were examined by Vickers microhardness measurements and compression testing.
A Model for Particle Dissolution and Precipitation in HSLA Steels
Authors: Borggren Ulrika , Engberg Göran , Siwecki Tadeusz
Published: March 2009

Precipitation of carbonitrides has been studied in as-cast slabs of one Nb and
one Nb and Ti containing HSLA steel. The precipitates have been quantified using LOM
and TEM. The measured size and number distributions was then compared to model
calculations of precipitate nucleation and growth using estimates of the cooling rates in
the austenitic range (1490oC to 800oC) during casting. Both average size and number
distributions could be modelled with good agreement using identical model parameters
(except for individual diffusion coefficients for the participating species).
The model is based on classic nucleation rate theory and a quasistationary
approximation for growth of spherical particles. Local equilibrium is assumed at the
phase boundary.
Tertiary Scale Behaviour during Finishing Hot Rolling of Steel Flat Products
Authors: Suárez Lucia , Bourdon G. , Vanden Eynde X. , Lamberigts M. , Houbaert Yvan
Published: March 2009

Steel strip surface oxidation during hot mill processing represents an industrial and
environmental problem: secondary oxide is removed after roughing, but tertiary oxide scales
already start to form before entering the finishing stands. Their properties affect the final steel
surface quality and its response to further processing. Controlling the oxide layer growth kinetics
and mechanical properties can make pickling easier and improve downstream behaviour. A thin
wustite-dominated scale layer (<20 μm) is created under controlled conditions in an original
laboratory device adequately positioned in a compression test machine to investigate plane strain
compression. A first series of oxidation tests were performed on a ULC steel grade to measure the
kinetics of oxide scale growth. The samples were first heated up under a protective atmosphere
(nitrogen), before being oxidised in air at different temperatures for various oxidation times. These
experiments can be considered fair quantitative and qualitative simulations of scale growth as it
occurs in a hot strip mill, insofar as the results thus obtained are in good agreement with the
literature. After the oxide growth, plane strain compression (PSC) was performed immediately to
simulate the hot rolling process. The oxide layers were characterised before and after compression
tests by optical and secondary electron microscopy. As expected, the oxide is seen to deform during
compression. The obtained oxide layers exhibit good adhesion to the substrate and homogeneity
over the thickness, even after compression.
Formation of Ultrafine Grained Low Carbon Steels via Martensite Deformation and Annealing
Authors: Azizi-Alizamini H. , Militzer Matthias , Poole Warren J.
Published: March 2009

Recently, there has been a large interest in the development of low carbon steels with
ultra fine grain structure using lean chemistries. Although these steels typically have superior
strength, the lack of work hardening capability limits the uniform elongation and thus the
formability of these kinds of steels. It has been reported by Tsuji and co-workers (2002) that
straining of martensite as an initial structure can yield an ultra fine grain structure with good
combination of strength and ductility. However, the detailed mechanism of the grain refinement has
not yet been clarified. In the present work, the annealing behavior of a low carbon martensitic
structure with and without deformation at room temperature has been systematically studied. It is
proposed that the process of concurrent softening due to recovery and recrystallization and
precipitation of carbides is different for the deformed and undeformed materials. Further,
preliminary results have been found on the role of substitutional alloying elements such as Mo or Cr
on the kinetics of the softening processes.
Selective Oxidation of Manganese and Chromium during Annealing of Low Carbon Strip Steels
Authors: Wilson P.R. , Chen Z. , Killmore Chris R. , Laird Stuart J.
Published: March 2009

Surface graphitization is a well known defect that occurs when low carbon steel strip is
batch annealed. A small addition of chromium (about 0.04 wt %) can be used to minimize the
surface graphitization. However chromium and some other alloy elements, such as manganese used
in this class of steel, have higher affinities for oxygen than iron. Therefore it is possible for them to
be oxidized during batch annealing in a reducing environment to iron. Selective oxidation of these
two elements gives rise to a risk of forming different surface defects that may affect the quality of
the tinned surface. The edge defect is characterized as a region of low reflectivity on the tin plate
product caused by grain boundary precipitates. A porous tin coating with a dull appearance is
produced in the affected areas. Not only are the aesthetical values of the finished tin plate product
affected but the corrosion resistance is also reduced.
In this investigation surface oxides formed at grain boundary of low carbon steels annealed at
700°C in 5% hydrogen 95% nitrogen atmosphere were characterized using scanning electron
microscopy and transmission electron microscopy. Two different oxide particles (Fe,Mn)O and
MnCr2O4 were observed at the grain boundaries with the former five-fold coarser than the latter. It
was found at the annealing temperature of 700°C, that the mean particle size of the (Fe,Mn)O
depends on the manganese content, while the mean particle size, and distribution of the MnCr2O4
was dependent on chromium, but independent of manganese. The coarse (Fe,Mn)O precipitates
pose no potential risks to electrolytic tinning as they will be removed by the pickling operation prior
to tinning. Controlling the chromium content of the steel can minimize the potential risks posed by
the MnCr2O4 to the quality of electrolytic tinning.
Enhancing Surface Properties of Fine Grain Duplex Stainless Steel via Superplastic Carburizing
Authors: Masdek Nik Rozlin Nik , Jauhari Iswadi , Ogiyama Hiroyuki , Hasan Rafidah
Published: March 2009

In this research, a new type of surface carburizing method which combines
superplastic phenomenon and carburizing process called superplastic carburizing (SPC) was
introduced. Thermo-mechanically treated duplex stainless steel (DSS) with fine grain
microstructure and exhibits superplasticity was used as the superplastic material. The SPC was
conducted at temperatures ranging from 1123 K to 1223 K for various durations. Initial loads of
25 MPa, 49 MPa and 74 MPa were applied to give the superplastic deformation effect on the
carburized specimens. Metallographic studies revealed a thick, uniform, smooth and dense
morphology of hard carbon layer formed at the surface of fine grain DSS. The resulting case
depth of carbon layers were between 15 μm to 76 μm. A remarkable increase in surface hardness
was observed in the range of 600 HV to 1600 HV. The kinetics of this process in terms of carbon
diffusion and its variation with processing time and temperature was achieved using Arrhenius
equation. Activation energy (Q) was determined as 151.87 kJ/mol. Based on the results obtained,
SPC process can significantly enhance the surface properties of DSS.
Engineering Biomaterials Surfaces Using Micropatterning
Authors: Gagne Louis , Laroche Gaetan
Published: March 2009

A new technique for micropatterning surfaces for cell growth support is described
and characterized. This technique allows covering of large three-dimensional surfaces at low
cost with controllable micropatterns. This method takes advantage of the random properties of
aerosols and the principles of liquid atomization. Parameters of interest were the pressure of
atomization air, the flow rate and volume of the atomised liquid, and the distance between the
spray nozzle and the surface of the sample. The experimental setup permitted to obtain mean
diameters of spots between 10 and 20 microns with a maximum surface coverage of 20%. In
an initial step, polytetrafluoroethylene (PTFE) films were treated with ammonia plasma to
insert amino groups on the surface. The ammonia plasma treated films were immersed in a
solution containing sulfosuccinimidyl 4-(N-maleidomethyl)cyclohexane-1-carboxy-late (SSMCC)
to permit the introduction of maleimido groups on the PTFE surface to subsequently
conjugate peptides through a sulfhydryl containing N-terminal cystein residue.
Plasma/S-SMCC pretreated surfaces were then sprayed with peptide sequences CGRGDS and
CWQPPRARI. Our data showed that spots of CGRGDS peptides over a background of
CWQPPRARI peptides were the most effective combination to enhance endothelialization.
Original Position Statistic Distribution Analysis for Al Inclusion in Continuous-Casting Thin Slab
Authors: Gao Hong Bin , Yuan Liang Jing , Wang Hai Zhou
Published: March 2009

Single discharge analysis and comparison of signals of multi-channels, two kinds of
technique of Original position statistic distribution analysis, were used to analyze and
evaluate the Al inclusion in continuous-casting thin slab. The samples are continuous casting
slab . Datum of Al inclusions such as average concentration and concentration distribution ,
types of inclusion, concentration of the different type of Al inclusion, size distribution are
obtained on different sect of cross section and the whole cross section of the sample.
Fatigue Strength and Fracture Mechanisms of IF28 Steels
Authors: Islam M.A. , Tomota Yo
Published: March 2009

Interstitial free (IF) steels are widely used as thin sheet in the automobile industries
because of their many favorable properties. Although, fatigue properties of IF steels do not have
significant importance to auto body makers, however, they are very concerned about the tensile and
fatigue strength of the steels used for structural purposes to ensure safety of passengers. So, fatigue
results of this steel might help researchers to understand the behaviors of high strength steels. In this
study cyclic and static properties have been studied at room temperature in the air. Initiative has
also been taken to observe the fatigue fracture morphology of this steel. Experimental results show
that the fatigue limit is corresponding to about 40% of tensile strength and 80% of the yield strength
of this steel. Fractographic observations reveal a mixed type of fracture mode (intergranular and
transgranular cracking) fractures.
Correlation Analysis of MnS Inclusion Composition Using Original Position Statistic Distribution Analysis
Authors: Jia Yun Hai , Wang Hui , Wang Hai Zhou
Published: March 2009

In the process of Original Position Statistic Distribution Analysis, many abnormal
higher spark signals exist. They are believed as inclusion signals. Analyzing the time sequence and
position of the abnormal spark, It is found that the higher spark signals for S and Mn will appear
simultaneously . The reason is that MnS inclusion caused the element concentration enrichment at
these zone. Mixing some pure MnS crystal in pure iron powder and pressed by Heat Isostatic
Pressing technology, reference samples of MnS inclusion were made . Criteria of abnormal higher
spark signals for Mn and S is the measured value from the “blank sample ”.After analyzing the
spark behavior of these reference samples using OPA instrument, we can calculate the MnS
inclusion concentration through such method. steel samples were analyzed and results is
satisfactory.
Properties of Vacuum Sintered Duplex Stainless Steels
Authors: Dobrzański Leszek Adam , Brytan Z. , Grande Marco Actis , Rosso Mario
Published: March 2009

This work presents the possibility of obtaining duplex stainless steels through powder
metallurgy technology starting from austenitic X2CrNiMo17-12-2, martensitic X6Cr13 powders by
controlled addition of alloying elements, such as Cr, Ni, Mo, Cu in the right quantity to obtain the
chemical composition of the structure similar to biphasic one. Moreover the ferritic stainless steel
X6Cr17 has been mixed to austenitic stainless steel in the ratio of 50%-50% in order to exam the
deriving structure after sintering. In the studies behind the preparation of mixes, Schaffler’s diagram
was taken into consideration. Prepared mixes of powders have been compacted at 800 MPa and
sintered in a vacuum furnace with argon backfilling at 1260°C for 1 hour; after sintering rapid
cooling has been applied in N2.
Atomic Force and Confocal Microscopic Studies of Collagen-Cell-Based Scaffolds for Vascular Tissue Engineering
Authors: Amadori Luca , Rajan Navneeta , Vesentini Simone , Mantovani Diego
Published: March 2009

Collagen is the most used naturally occurring scaffold material. It’s a structural protein
ubiquitous among mammalian. The ability of collagen type I to host different cell phenotype in
vitro and its low antigenecity in vivo are well known. However, the principal drawback of collagenbased
materials consists in their low mechanical properties. For vascular tissue engineering this
represents a major limit, as the aim is to mimic the structure of a native vessel, which is known to
be resistant and viscoelastic. Moreover, vascular cells are known to be susceptible in vivo to
reorganize the matrix in which they proliferate. Therefore, the aim of this project is to study the
micro structural organization of collagen-based scaffolds, and to assess the interactions between
collagen and smooth muscle cells during regeneration. This knowledge will then allow the
development of appropriate strategies to tailor the microstructure of the scaffold and its properties.
Smooth muscle cells (SMCs) were selected to study the interactions between cells and matrix
during the proliferation. Atomic Force Microscopy (AFM) in dry state in tapping mode and
Confocal Laser Scanning Microscopy (CLSM) in reflection mode were used to investigate the
microstructure of the scaffold. For the former technique cells were seeded on top of the collagen gel
after jellification, while for the latter, cells were embedded into the collagen gel and stained with
Rhodamine. The contact points between matrix and cells were investigated, as well as the capacity
of vascular cells to induce a structural reorganization of collagen fibrils in the scaffold.
Change in Stress Axis with Creep Deformation in PST Crystal
Authors: Sakurada Eisaku , Matsuo Takashi
Published: March 2009

The superiority of creep in Ti-48at%Al alloy with fully transformed lamellar structure to that in
Ti-50at%Al alloy with γ single phase is characterized by the extension of transient stage. This
extension of the transient stage derives by the retarding effect of α2 plate on the onset of the
accelerating stage, through suppressing the dynamically recrystallization which is the main reason
of the accelerating stage. This superiority in Ti-48at%Al alloy will become more clear by
investigating the creep of the single crystal designated as the PST crystal, because of removing the
grain boundaries which is the formation site of dynamic recrystallization. By using the PST crystal,
the predominant deformation using primary slip plane of γ plate will continue, because the α2 plate
restricts the operation of other slip planes. In PST crystals with the angle between the stress axis and
the lamellar plates, designated as φ, less than 45°, the uniform deformation will proceed, because of
the decrease in creep rate due to the decreasing in Schmid factor through the monotonous decrease
in φ. But these suppositions have not confirmed.
In this study, the deformation manner of the PST crystals with φ of less than 45° is investigated
by the analyzing of creep curve, macrostructure and inverse pole figure of the PST crystals
interrupted the creep tests at 1148K/68.6MPa at the strains of 0.20 and 0.65. Inverse pole figures of
PST crystal are obtained using SEM-EBSD method. By accepting the creep deformation, the stress
axes of the PST crystals move for [001]-[1,
–
11] line with slip system of (111)<1,
–
01>, and after
reaching at this line, the stress axis turn to [1,
–
11] pole position with (111)<1,
–
10> slip system. The
change in stress axis is not homogeneous in gauge portion accepting small strain, by subjecting the
further creep deformation up to the onset of the accelerating stage, this heterogeneous deformation
in gauge portion disappeared.
Electrical Characterization of Aged Waspaloy Microstructures
Authors: Kumar V.Siva , Kelekanjeri G. , Gerhardt Rosario A.
Published: March 2009

Non-destructive evaluation (NDE) techniques offer the potential advantage of achieving
fast throughput microstructural characterization as well as monitoring that could be extremely
valuable in assessing the mechanical integrity of turbine engine components. It is well known that
the γ′ precipitate size and distribution can often determine the mechanical strength of nickel base
alloys.
In this investigation, Waspaloy, an age-hardening superalloy, was chosen as the candidate to
produce varied microstructures, which were subsequently characterized via the DC four-probe
resistivity method. Specimens with average grain sizes of 13, 52 and 89 μm were obtained upon
solutionizing at 1045°C, 1090°C and 1145°C respectively. The specimens were annealed at 1045°C
to stabilize the vacancy concentration prior to aging at 800°C for times ranging from 0.1 to 100
hours. Sub-grain microstructures examined in the SEM showed progressive growth of γ′ precipitates
with increased aging duration in all cases. The measurements of DC four-probe resistivity showed a
consistent drop in the resistivity with increased aging time, which was concurrent with the growth
of the precipitates.