bluuebunny/crossref_metadata_2025 huggingface dataset:
Pulsed Laser Deposition of Sm0.2Ce0.8O1.9/Zr0.9Sc0.1O2 Bilayer Films for Fuel Cell Application
Authors: Yang Dong Fang
Published: March 2009

Samarium doped ceria exhibits relative high conductivity of 0.1 S/cm at 700 °C and has been
considered to be an attractive electrolyte for solid oxide fuel cells operating at the temperature range
between 500 to 600 °C. Although the material exhibits better chemical and structural compatibility
with electrodes as well as higher ionic conductivity than Yttria-stabilized Zirconia, the reduction of
Ce4+ to Ce3+ induces n-type electronic conduction which tends to decrease power output of solid
oxide fuel cells. The problem can be eliminated by using a barrier of thin Zr0.9Sc0.1O2 layer
deposited over SDC layer as an alternative electrolyte to improve the stability of Samarium doped
ceria under reducing atmosphere.
In this work, we will report the results on the development of the Pulsed Laser Deposition (PLD)
process to fabricate Sm0.2Ce0.8O1.9/Zr0.9Sc0.1O2 bilayer films. Bilayer films with controlled
microstructures, density, and interfacial properties were successfully grown by the PLD at various
deposition temperatures on Si(100) substartes. X-ray diffraction was used to determine their crystal
structures, while the cross section images of the film-film and film-substrate interfaces were
examined by field-emission SEM. The film density was calculated from the index of reflection data
determined by a fiber-optic spectrophotometer.
Plasma Spray Processing of Solid Oxide Fuel Cells
Authors: Kesler Olivera
Published: March 2009

Plasma spray processing is a low-cost, rapid manufacturing technique that is widely used
industrially for fabrication of thermal barrier and wear- and corrosion-resistant coatings. Because
the technique can be used to rapidly deposit coatings of high melting temperature materials with
good substrate adhesion, it has also been applied to the production of individual component layers
in tubular solid oxide fuel cells (SOFCs), and more recently, in planar SOFCs. The use of plasma
spray processing for the fabrication of fuel cell components presents unique challenges, due to the
high porosities required for the electrode layers and fully dense coatings required for electrolytes.
Application of plasma spray processing for the manufacture of solid oxide fuel cells is discussed,
with consideration of potential advantages of the technique compared to standard SOFC wet
ceramic processing routes. Major challenges faced in the adaptation of the processing method to
solid oxide fuel cell manufacture are discussed, along with current research approaches being used
to overcome these challenges. Recent developments in the use of the technique for the rapid onestep
manufacturing of direct oxidation SOFC anodes are discussed, for composite material
combinations that cannot be co-sintered due to widely divergent melting points. The impacts of
plasma sprayed coating properties on solid oxide fuel cell performance are considered, and
implications of the use of the technique on overall stack and system manufacturing costs are
discussed.
A Study on Co and Cu Oxides as Sintering Aids for Sm0.2Ce0.8O1.9 Electrolyte
Authors: Zhang Xin Ge , Decès-Petit Cyrille , Yick Sing , Robertson Mark , Qu Wei , Xie Yong Song , Hui Rob , Styles Edward , Roller Justin , Kesler Olivera , Maric Radenka , Ghosh Dave
Published: March 2009

In this study, an addition of Co and Cu oxides to Sm0.2Ce0.8O1.9 (SDC) was studied to
improve the SDC sinterability. It has been found that both Co and Cu oxide are very effective as
sintering aids, and the SDC sintering temperature can be reduced from 1400°C without aids to
below 1000°C with only 1at.% of either Cu or Co. As compared to the pure SDC, a slight decrease
of ionic conductivity was observed in SDC with Cu sintering aid. There is no obvious effect on
electrochemical property of SDC with Co sintering aid under 2.5at.%.
Studies on Suppression of Hydrogen Evolution Reaction for Zinc/Air Fuel Cell
Authors: Lee Chang Woo , Sathiyanarayanan K. , Eom Seung Wook , Yun Mun Soo
Published: March 2009

We studied the electrochemical behavior of a zinc oxide anode in the presence of
succinic acid as an organic additive. This additive was added to the electrolyte, which is 8.5 M
KOH solution containing 25g of ZnO and 3000 ppm of polyethylene glycol in 1 liter of water. The
modified electrolyte was newly attempted to improve the main problems namely the hydrogen
overpotential and dendrite formation during cycling in Zn/Air energy system. The results obtained
in the presence of succinic acid were compared with the behavior of the electrolyte 8.5 M KOH in
the absence of the additive. It has been concluded that the hydrogen overpotential is raised
enormously, shifting to the more negative potential side as -4.19 V vs. Hg/HgO while zinc oxide
electrode was at -1.399 V. Similarly, we found that dendrite formation on the surface of zinc oxide
anode is reduced to some extent by scanning electron micrographs.
Neutron Incoherent Scattering Measurements on Hydrogen-Charged Zircaloy-4
Authors: Garlea E. , Garlea V.O. , Choo Hahn , Hubbard C.R. , Liaw Peter K.
Published: March 2009

Neutron incoherent scattering measurements were conducted on Zircaloy-4 round
bars. The specimens were charged in a tube furnace at 430 °C, using a 12.5 vol. % hydrogen
in an argon mixture for 30, 60, and 90 minutes at 13.8 kPa pressure. The volume-average
neutron diffraction measurements showed the presence of the face-centered-cubic delta
zirconium hydride (δ-ZrH2) phase in the hydrogenated specimens. The assessment of the
background in the diffraction profiles due to the incoherent scattering from the hydrogen
atoms was carried out by performing inelastic scans around zero energy transfer and at a
fixed two-theta value for which there was only flat background and no coherent scattering.
To estimate the relative amount of hydrogen in the Zircaloy-4 samples, the increase in
incoherent scattering intensities with hydrogen content was calibrated using samples for
which the hydrogen content was known. Measurement of the background scattering from
locations within the round bar was also performed to map the distribution of hydrogen
content.
Identification of the Chirality and Polarity of Intermetallic Compounds with the Point Groups of 23, 432, 422, and 321 by Electron Diffraction
Authors: Inui Haruyuki , Tanaka Katsushi , Kishida Kyosuke , Fujio Satoshi
Published: March 2009

A CBED (convergent-beam electron diffraction) method proposed by the present authors
for chiral identification of enantiomorphic crystals has been successfully applied to intermetallic
compounds with the point groups of 23, 422, 432 and 321. The intensity asymmetry of ZOLZ
and/or FOLZ reflections of the Bijvoet pairs is easily recognized in CBED patterns with the
incidence along the appropriate zone-axis orientations for each of the two members of the
enantiomorphic pair and the intensity asymmetry with respect to the symmetry line is reversed
upon changing the space group (handedness) from one to the other. Thus, the generality of the
proposed method in identifying the chirality for all crystallographycally possible enantiomorphic
crystals is verified.
Analysis of the Solidification Microstructure of Multi- Component γ-TiAl Alloys
Authors: Oehring Michael , Küstner V. , Appel Fritz , Lorenz Uwe
Published: March 2009

Gamma titanium aluminide alloys often solidify peritectically and show a coarse,
dendritic microstructure, which can lead to unacceptable mechanical properties in the as-cast
condition. In view of the development of improved cast alloys, the dependence of the solidifying
microstructure on the aluminum content and other alloying elements was investigated. The
formation of the observed solidification microstructures is discussed in comparison with
microstructure formation maps calculated by the NCU (nucleation and constitutional undercooling)
model developed by Hunziker et al. [1].
Effect of RE Elements and Ni Contents on the Microstructure and Mechanical Properties of Rapidly Solidified Mg Ribbons
Authors: Gonzáles Sergio , Pérez P. , Garcés G. , Adeva P.
Published: March 2009

The effect of the concentration of Ni, Y and La-rich mischmetal on the
thermal stability, microstructure and mechanical properties of ribbons tested in the
temperature range 25-350°C have been evaluated. The low-alloyed materials were
crystalline or partially crystalline while high-alloyed materials were amorphous. The
amorphous alloys experienced numerous transformations during heating above 170°C.
A transition in the amorphous state was observed in all alloys prior to the crystallization
stage. The alloy composition determines the sequence of phase transformations during
crystallization. In general, the structure of crystallised amorphous, even at high
temperatures, is much finer than that of crystalline materials. A MgxREy intermetallic
matrix with other intermetallic phases homogeneously distributed was observed in the
crystallised ribbons with high RE contents. However, a magnesium matrix embedding
other intermetallic phases was the microstructure observed for low-alloyed materials.
The amorphous Mg-10Ni-2.5Y2.5-2.5La(MM) showed the higher tensile strength
values up to 200 °C The crystalline Mg-2Ni-1Y-1La(MM) ribbon and the partially
crystalline Mg-3Ni-1.5Y-1.5La(MM) alloy also exhibited high mechanical resistance
levels which were maintained up to 250 °C. MgNi10Y2.5La(MM)2.5 amorphous and
MgNi3Y1.5La(MM)1.5 crystalline broken above 500 and 400 MPa, respectively, at 100°C
Mechanical Properties and Damping Behavior of Magnesium Alloys Processed by Equal Channel Angular Pressing
Authors: Zheng Ming Yi , Hu Xiao Shi , Xu Shi Wei , Qiao Xiao Guang , Wu Kun , Kamado Shigeharu , Kojima Yo
Published: March 2009

Equal channel angular pressing (ECAP) was applied to commercial pure magnesium
alloy, Mg-1wt%Si alloy and Mg-4.2wt%Zn-0.7wt%Y alloy. With increasing ECAP passes, both
tensile strength and ductility of the alloys are increased, which are mainly resulted from the grain
refinement. At the same time, for the Mg-Zn-Y alloy with inherent low damping capacity, damping
capacity is increased after ECAP passes, however, the damping capacity is still low even after
6-pass ECAP. While for the commercial pure magnesium and Mg-Si alloy with inherent high
damping capacity, although the damping capacity is decreased obviously after ECAP, Q-1 is still
greater than 0.01. The damping capacity after ECAP processing is mainly influenced by grain size
and deformation microstructure. ECAP paves a way for the development of magnesium alloys with
high strength and high ductility combined with high damping capacity.
Development of a High Strength Mg-Zn-Y-Zr Wrought Alloy
Authors: Chen Rongshi , Tang Wei Neng , Xu Dao Kui , Han En-Hou
Published: March 2009

The effects of Y addition to the Mg-Zn-Y-Zr alloy on the change of the microstructure
and the mechanical properties (with the Y content range of 1 to 3 wt%) have been investigated. It
shows that when Zn content is constant (5.65wt%), the alloys with Y content between 1.17 and
1.72wt% nearly reach its highest strength. With the composition near the optimums, the extruded
Mg-6%Zn-1%Y-Zr alloy shows high strength and excellent ductility. The deformation behavior of
this new alloy at high temperature has also been studied. Moreover, the super-long fatigue
behavior of the Mg-6%Zn-1%Y-Zr alloy has also been tested, the results show the alloy with a
high fatigue strength of about 85-90MPa in the super-long fatigue life regime of 1×109 cycles.
Effect of Solidification Grain Refinement on the Development of Wrought Mg Alloys
Authors: Easton Mark , Davies Chris H.J. , Barnett Matthew R. , Pravdic Franka
Published: March 2009

A recent trial investigated the effect of solidification grain refinement of billet on the grain
refinement and properties of alloy ZM20. It was found that even at levels of 0.4Mn, significant grain
refinement could be obtained when 0.7Zr was added. At 0.2Mn grain sizes as low as 60μm were
obtained. Billets of Mg-2Zn-0.2Mn with four different grain sizes, due to different Zr and cooling
rates were then cast via vertical direct chill casting and extruded conventionally. Benefits of grain
refinement of the billet on extrusion were found to be a slight increase in the size of the operating
window, and a reduction of the grain size in the extrudate. However, the effect of the reduction in
extrudate grain size due to refinement of the billet was small compared with the amount of grain
refinement obtained due to recrystallisation on extrusion.
Evolution of Microstructures during Laser Surface Cladding of Magnesium Alloy Castings Using Welding Wire
Authors: Cao Xin Jin , Xiao Min , Jahazi Mohammad , Shariff Tasneem
Published: March 2009

The feasibility of laser repair was studied based on single-/two-layer multi-bead cladding
using a continuous wave (CW) 4 kW Nd:YAG laser system and 1.6-mm EZ33A-T5 filler rods for
22.5-mm ZE41A-T5 magnesium alloy sand castings in the machined surface conditions. The results
demonstrate the potentiality of repairing magnesium castings using laser surface cladding by wire.
Similarly to weld joints, three distinct regions, i.e. clad, partially melted and heat affected zones are
observed in the laser-clad beads. The microstructures in these zones and their evolutions are
discussed in details.
Hydrogenation and Degradation Behaviors of Mg-Ni Alloys
Authors: Ha Won , Youn Jeong Il , Kim Young Jig
Published: March 2009

In this study, melting and casting of Mg-Ni alloys in ambient atmosphere for mass
production, nickel content adjustment for enhancing hydrogen capacity and reducing alloy weight,
and cyclic hydriding/dehydriding test for evaluation of degradation properties were investigated.
Mg-Ni alloys were fabricated by Rotation-Cylinder Method (RCM) in ambient atmosphere.
Hydriding/dehydriding reactions were repeated 350 times at 350°C to evaluate degradation
property. SEM-EDS analysis revealed that the lamellar eutectic structure of Mg-Ni alloy consists of
Mg-rich α-phase and β-Mg2Ni. It is supposed that the lamellar eutectic structure enhances
hydrogenation properties of Mg-Ni alloys.
Microstructure Evolution of AZ31 Magnesium Alloy during Warm Compression Forming
Authors: Zhang Zhi Min , Wang Qiang , Li B.C. , Zhang X.
Published: March 2009

Warm compression tests of AZ31 Mg alloy were carried out at five temperatures in
30°C intervals from 210°C to 330°C. The samples of different thickness which were machined
from as-cast and pre-strained AZ31 billets were compressed into thickness 1mm and then cooled in
the air to room temperature. The microstructural evolution of AZ31 Mg alloy was investigated
during warm compression forming. The results show that all the samples have undergone a
microstructure changes to different scales in the range investigated. The twinning is the
predominant deformation mechanism for magnesium alloys at moderate temperatures and its
occurrence is dependent on temperature and strain. Microstructural evaluation indicates that the
mean size of the recrystallised grains decreases with increasing effective strain and temperature
because of sufficient dynamic recrystallization. The original grain has significant influence on
microstructural evolution during warm forming.
Metal Foam Production Process Using Hydro-Gel and its Improvement
Authors: Shimizu Toru , Matsuzaki Kunio
Published: March 2009

Already, we are developing the process to produce stainless steel foam over 97% porosity
using hydro-gel binder. However, this process is very sensitive process, and foaming condition is
affected by the slight deference of heating temperature. Therefore, we tried to improve the process
by changing the foaming agent and foaming conditions. By the improvement of the process, the
foaming operation becomes stable and finer cell size stainless steel foam can be obtained.
Micromechanical Models of Metallic Sponges with Hollow Struts
Authors: Daxner Thomas , Bitsche Robert D. , Böhm Helmut J.
Published: March 2009

Coating of a precursor structure, which is subsequently removed by chemical or thermal
treatment, is a technology for producing cellular materials with interesting properties, for example in
the form of metallic sponges with hollow struts. In this paper idealized models for determining the
effective elastic properties of such materials are presented. The chosen models for the structures are
space-filling, periodically repeating unit cell models based on idealized models of wet foams, which
were generated with the program ‘Surface Evolver’. The underlying topology is that of a
Weaire-Phelan structure. The geometry of the micro-structures can be described by two principal
parameters, viz. the volume fraction of solid material in the precursor structures, which determines
the shape of the final structures, and the thickness of the metallic coating, which defines their apparent
density. The influence of these two parameters on the macro-mechanical behavior is investigated. The
elastic properties of the micro-structures are described by three independent elastic constants owing to
overall cubic material symmetry. The dependence of the effective Young’s modulus on the direction
of uniaxial loading is investigated, and the elastic anisotropy of the structures is evaluated.
Local Structures around Zr, Ni and Cu for the Zr67Cu33 and Zr67Ni33 Metallic Glasses
Authors: Matsuura M. , Sakurai Masaki , Zhang Wei , Inoue A.
Published: March 2009

XAFS measurements of the Cu, Ni and Zr K-edges for the melt-quenched Zr67Cu33 and Zr67Ni33
metallic glasses were curried out using synchrotron radiation at 20K. Fitting calculations for the
EXAFS results reveal that local structure around Ni and Zr in Zr67Ni33 is well represented by those
for the crystalline Zr2Ni, while local structure around Zr in Zr67Cu33 is better fitted by an
icosahedron rather than crystalline Zr2Cu. Such differences of the local structure attribute to the
differences of the stability of super-cooled liquid state and glass formability between Zr67Cu33 and
Zr67Ni33 metallic glasses.
Materials Engineering for Solid Oxide Fuel Cell Technology
Authors: Brandon N.P.
Published: March 2009

Materials engineering plays vital role in Solid Oxide Fuel Cell (SOFC) technology. For example,
engineered porous materials are needed to support delicate electrolyte membranes, where
mechanical integrity and effective diffusivity to fuel gases is critical; and to construct fuel cell
electrodes, where an optimum combination of ionic conductivity, electronic conductivity, porosity
and catalyst distribution is critical. Material engineering also underpins selection of cell designs and
material systems to minimise failure, particularly during transient operations such as thermal
cycling. The paper will address these issues, making reference to high temperature (>900C) SOFCs
for integration with gas turbines, and metal supported SOFCs designed to operate at temperatures of
500-600C.
Room Temperature Plasticity of Zr65Al7.5Ni10Cu17.5-xPdx Bulk Metallic Glasses
Authors: Yoshimi Kyosuke , Kato Hidemi , Saida Junji , Inoue Akihisa
Published: March 2009

Monolithic Zr65Al7.5Ni10Pd17.5 and Zr65Al7.5Ni10Cu17.5 hardly had plastic deformability in
tension at room temperature, although Zr65Al7.5Ni10Pd17.5 showed a large plastic strain in
compression. A depressed zone that is the evidence of viscous flow deformation (so-called viscous
flow depression zone; VFD-zone) was observed for Zr65Al7.5Ni10Pd17.5 around the edge at the point
of failure on its specimen surfaces. However, no VFD-zone was seen for Zr65Al7.5Ni10Cu17.5. Thus,
a clear difference in tensile plastic behavior was found between Zr65Al7.5Ni10Pd17.5 and
Zr65Al7.5Ni10Cu17.5. A structural change in the vicinity of the fracture surface of Zr65Al7.5Ni10Pd17.5
was measured by micro-beam X-ray diffractometry (MB-XRD). We may be able to discuss the
room temperature plasticity of Zr65Al7.5Ni10Cu17.5-xPdx bulk metallic glasses correlating with the
phase stability of the amorphous and icosahedral quasi-crystalline phases.
Formation, Mechanical and Magnetic Properties of (Fe,Co)-B-Si-Nb Bulk Glassy Alloys
Authors: Shen Bao Long , Inoue Akihisa
Published: March 2009

Fe- and Co-based bulk glassy alloys (BGAs) with diameters up to 5 and 4 mm were
formed respectively in (Fe,Co)-B-Si-Nb system by copper mold casting. The Fe-based glassy alloys
in [(Fe1-xCox)0.75B0.2Si0.05]96Nb4 system exhibit saturation magnetization (Is) of 0.84-1.13 T and low
coercive force (Hc) of 1.5-2.7 A/m. Its BGAs exhibit superhigh strength ( σ
f) of 3900-4250 MPa,
Young’s modulus (E) of 190-210 GPa, elastic strain (εe) of 0.02 and plastic strain (εp) of 0.0025. For
the Co-based glassy alloys in [(Co1-xFex)0.75B0.2Si0.05]96Nb4 system, in addition to superhigh σ
f of
3980-4170 MPa, they also exhibit excellent soft magnetic properties, i.e., Is of 0.71-0.97 T, Hc of
0.7-1.8 A/m, high effective permeability (μe) of 1.48-3.25×104 at 1 kHz under a field of 1 A/m, and
extremely low saturation magnetostriction (λs) of 0.55-5.76×10-6.
Localized Shear Deformation and Fracture in a Zr-Based Bulk Metallic Glass
Authors: Morikawa Tatsuya , Kawada Tetsuro , Higashida Kenji
Published: March 2009

Behaviors of fracture and deformation in a Zr-Al-Ni-Cu bulk metallic glass(BMG) was
investigated by using three-point bending tests. Apparent fracture toughness obtained by bending test
was 40MPam1/2 which is comparable to the value of ductile crystalline metals. This high toughness of
the BMG should be understood by the crack-tip plasticity as well as crystalline metals. It is well
known that plastic deformation occurs very inhomogeneously when BMGs are deformed at room
temperature. Such inhomogeneity is manifested by the appearance of surface steps caused by
localized shear deformation. In the present study, the surface steps due to the localized shear bands
near a fracture surface have been examined in detail by using SEM and AFM, where much attention
has been paid on the variation of the surface step height measured along the localized shear band. The
variation of the step height indicates the gradient of plastic shear deformation, and it can be
understood, in principle, as the introduction of elastic singularities corresponding dislocations in the
case of crystalline materials.
Glass Forming and Thermal Properties of the Mg65Cu25GD10-xNdx (x=0~10) Amorphous Alloys
Authors: Chang L.J. , Yang B.C. , Chiang P.T. , Jang Jason S.C. , Huang J.C.
Published: March 2009

The Mg65Cu25Gd10-xNdx (x=0 ~ 10) amorphous alloy rods with 3~6 mm in diameter were
prepared by Cu-mold injection method. The thermal properties and mechanical properties of these
amorphous alloys have been investigated by DSC, SEM with EDS capability, X-ray diffractometry
(XRD) and Vickers hardness test. The XRD revealed that these entire as-quenched
Mg65Cu25Gd10-xNdx alloy rods exhibit a broaden diffraction pattern of amorphous phase. A clear Tg
(glass transition temperature) and supercooled region (about 30~60 K) were revealed for all of those
Mg65Cu25Gd10-xNdx alloys. In addition, the single stage crystallization of the Mg65Cu25Gd10 alloy
was found to change into two stages crystallization when the Nd element was added into this alloy.
In parallel, the crystallization temperature (Tx) and supercooled region (Tx) presents a decreasing
trend with increasing Nd content. The lowest liquidus temperature (Tl, about 721 K) occurs at the
Mg65Cu25Gd8Nd2 alloy. In addition, The Mg65Cu25Gd8Nd2 alloy exhibits the high γ value (0.416,
defined as γ= Tx/Tg+Tl), a relatively high Trg (0.59, defined as Trg = Tg/Tl) and the highest hardness
in these alloys.
High Temperature Deformation Characteristics of Zr76.11Ti4.20Cu4.51Ni3.16Be1.49Nb10.53 Bulk Metallic Glass Composite
Authors: Jun H.J. , Lee Kwang Seok , Yoo Yeon Chul , Chang Young Won
Published: March 2009

The thermal properties of a Zr76.11Ti4.20Cu4.51Ni3.16Be1.49Nb10.53 bulk metallic glass (BMG) have
been investigated by using a differential scanning calorimeter (DSC). The composition of dendrite
phase was then subsequently analyzed by using an EPMA, XRD, and TEM. The glass transition and
crystallization onset temperatures were determined as 339.7 °C and 375.8 °C for this BMG,
respectively. The Zr-Ti-Nb dendrite phase was found to have a BCC structure. Mechanical
properties have also been examined by conducting a series of uniaxial compression tests at various
temperatures within supercooled liquid region under the strain rates between 10-4 /s and 3×10-2 /s.
The hardness of matrix and dendrite was then measured separately. The glassy matrix appears to
play major role on the elongation, while dendrite phase on the strength of this BMG composite at
high temperatures within supercooled liquid region.
Oxidation Behavior of the Y56Al24Co20 Bulk Amorphous Alloy Containing Crystalline Composites at 325-450°C
Authors: Hsieh H.H. , Kai W. , Lin C.Y. , Chin Tsung Shune
Published: March 2009

The oxidation behavior of Y56Al24Co20 bulk metallic glass containing ~4.2% Y-rich
particles was studied over the temperature range of 325-450oC in dry air. The results showed that
the oxidation kinetics of the alloy followed the parabolic rate law at T≤375oC, with rate constants
generally increased with temperature. Conversely, para-linear kinetics were observed at higher
temperatures (T≥400oC). The scales formed on the Y-base amorphous composite were temperature
dependent, consisting of exclusively yttrium oxides (Y2O3) at T≤375oC and of mostly Y2O3 and
alumina (Al2O3) at temperatures. No evidence of any cobalt-containing oxide was found in the scale.
Development of a Method for Making Interatomic Potential: An Application to Metallic Systems
Authors: Kumagai Tomohisa , Hara Shotaro , Izumi Satoshi , Sakai Shinsuke
Published: March 2009

A method for making interatomic potentials is proposed and is applied to Cu-Zr-Hf-Ni-
Al bulk-metallic-glass systems. The method consists of three steps. Firstly, potential function form
is determined so that bonding nature can be described. Secondly, materials properties used for
fitting are selected so that the potential has enough robustness. Here, it is noted that materials
properties must be added in accordance with the purpose of the study. Finally, potential parameters
have been optimized using global-search procedure. Developed potential well reproduces material
properties of them.
Estimation of Micro-Formability and FEM Simulation of Micro-Forming Process of a Zr-Based Bulk Metallic Glass
Authors: Na Y.S. , Kang S.G. , Park K.Y. , Lee Jong Hoon
Published: March 2009

Micro-forming is considered to be a suited technology to manufacture very small metallic
parts (several μm~mm). Zr-based bulk metallic glass, Zr62Cu17Ni13Al8, has been expected to be a
promising metallic material for micro-forming process due to their isotropy, low flow stress in a
wide supercooled liquid region and good stability of amorphous matrix. Therefore, one can expect
that micro-forming of Zr62Cu17Ni13Al8 might be feasible at a relatively low stress in the supercooled
liquid state without any crystallization during hot deformation. In this study, micro-formability of
Zr62Cu17Ni13Al8 bulk metallic glass was investigated for micro-forging of U-shape pattern. Microformability
was estimated by comparing Rf values (=Af/Ag), where Ag is corss-sectional area of U
groove, and Af the filled area by material. Micro-forging process was also simulated and analyzed
by applying the finite element method. The micro-formability of Zr62Cu17Ni13Al8 was increased
with increasing load and time in the temperature range of the supercooled liquid state. In spite of the
similar trend in the variations of Rf values, FEM simulation results showed much higher Rf values
than the experimental Rf values. This disagreement was analyzed based on the stress overshoot
phenomena of bulk metallic glasses in the supercooled liquid region. FEM simulation of the microstamping
process was applicable for the optimization of micro-forming process by carefully
interpreting the simulation results.
Dynamic Deformation and High Velocity Impact Behaviors of Ti-6Al-4V Alloys
Authors: Kim J.Y. , Shim In Ok , Kim H.K. , Hong S.S. , Hong Soon Hyung
Published: March 2009

Deformation behaviors under quasi-static and dynamic compression and high velocity
impact condition of Ti-6Al-4V ELI (extra low interstitial) alloys in two different conditions were
investigated. Mill annealed (MA) alloy, consisted of equiaxed α, and thermomechanically treated
(TMT) alloy, consisted of mixed structure of equiaxed α and transformed β, were prepared.
Compression tests were performed in low strain rate regime using hydraulic testing machine and
were performed in high strain rate regime using split Hopkinson pressure bar. High velocity impact
tests were also performed by impacting the test projectiles made of these alloys against a steel target
at a velocity of ~400m/s. The compression test results showed that deformation behaviors were
influenced by the strain hardening exponent at low strain rate regime, and by both the strain
hardening exponent and the strain-rate hardening rate at high strain rate regime. TMT alloy showed
higher strength but almost similar fracture strain as MA alloy at a high strain rate of ~6000/s, due to
the effect of strain-rate hardening. The high velocity impact test results showed that the projectile of
TMT alloy withstood without fracture at higher impact velocity, but the maximum amounts of
deformation prior to crack were nearly the same for both alloys. These results were in accord with
the results of compression tests at high strain rate regime, that is, higher strength but same fracture
strain of TMT alloy compared to MA alloy.
Web-Site Survey of Recent Ecomaterials in Japan
Authors: Yamada Katsutoshi , Halada Kohmei , Ijima Kiyoshi
Published: March 2009

The research was made on how ecomaterials are currently used in Japan. All the
information was obtained from 2001 to 2004 year version environmental reports on the Web-sites of
the organizations concerned. In this paper, about 3900 ecomaterials produced by approximately 280
listed companies on the stock market were researched and classified into six categories. The number
of ecomaterials produced in Japan has doubled in these several years and research activities in this
field seem to be getting rather well-balanced. Our effort is focused on the analysis of the
characteristics of "Greener process" and "Greener resource" type ecomaterials. The ecomaterials of
each industry have their own characteristics according to an industry to which they belong. And each
industry still has its own particular environmental subject to tackle.
Multi-Valent Metal Salt Hydrates as Catalysts for the Esterification of Fatty Acids and Alcohols
Authors: Mantri Kshudiram , Nakamura Ryo , Miyata Yasuyuki , Komura Kenichi , Sugi Yoshihiro
Published: March 2009

Some typical multi-valent metal salt hydrates, such as chloride, nitrate, sulfate, and acetate
of Fe3+, Al3+, Ga3+, In3+, ZrO2+, HfO2+, Zn2+, Co2+, Ni2+, Mn3+, Cr3+, and Cu2+ have catalytic activities
for the esterification of saturated and unsaturated fatty acids and alcohols. Supporting these metal salt
hydrates on ordered mesoporous silica such as MCM-41 enhanced the catalytic activity of the
esterification. The esters of C10-C18 normal acid and alcohol were obtained in high yield by some of
supported metal salt hydrates on MCM-41; however, the yield of the esters decreased with their chain
length of acids and alcohols although the activities depended on type of metal salt hydrates. The
catalyst is recyclable although some loss of activity was observed.
A Thermodynamic Description of the Al-Ir System
Authors: Abe Taichi , Ode Machiko , Murakami Hideyuki , Oh Chang Seok , Kocer Cenk , Yamabe-Mitarai Yoko , Onodera Hidehiro
Published: March 2009

The thermodynamic assessment of the Al-Ir binary system, one of the key sub-systems of
the Ir-based alloys, was performed using the CALPHAD technique. The AlIr(B2) phase was
described using the two sublattice model with the formula (Al,Ir)0.5(Ir,Va)0.5, while other
intermetallic phases were treated as stoichiometric compounds. The calculated data of the phases in
the Al-Ir system can be used to accurately reproduce experimental data, such as phase equilibria,
invariant reactions, and formation enthalpies of the intermetallic phases.
Computer Simulation of the Precipitate Evolution during Industrial Heat Treatment of Complex Alloys
Authors: Kozeschnik Ernst , Sonderegger Bernhard , Holzer Ivan , Rajek Joachim , Cerjak Horst
Published: March 2009

Precipitates are the key ingredient for the strength of heat treatable alloys. To optimize
the mechanical properties of alloys it is important to know the response of precipitates to thermomechanical
treatments. In the past, application of computer models to describe the evolution of
precipitates in the course of these processes has proven difficult due to the complexity of the
problem. In this work, a new model based on a mean-field representation of precipitates in a multicomponent
matrix is applied to heat treatments of steels. Example simulations are presented for a 9-
12% Cr ferritic/martensitic heat resistant steel for power plant application and a complex tool steel
with both carbides and intermetallic phases using the software MatCalc. The predictions of the
model are verified on experimental results and the potential application to industrial heat treatment
simulation is discussed.
Evolutionary Computing for Metals Properties Modelling
Authors: Abbod Maysam F. , Mahfouf M. , Linkens D.A. , Sellars C.M.
Published: March 2009

During the last decade Genetic Programming (GP) has emerged as an efficient
methodology for teaching computers how to program themselves. This paper presents research work
which utilizes GP for developing mathematical equations for the response surfaces that have been
generated using hybrid modelling techniques for predicting the properties of materials under hot
deformation. Collected data from the literature and experimental work on aluminium are utilized as
the initial training data for the GP to develop the mathematical models under different deformation
conditions and compositions.
Identification of Thermal Properties of the System Casting-Mould
Authors: Majchrzak Ewa , Mochnacki Bohdan
Published: March 2009

In the paper the problem of casting and mould thermophysical parameters identification
is discussed. So, it is assumed that in the mathematical model describing the thermal processes in
the system considered the selected parameter (or parameters) is unknown. On the basis of additional
information concerning the cooling (heating) curves at the selected set of points the unknown
parameter can be found. The inverse problem is solved using the least squares criterion in which the
sensitivity coefficients are applied. On the stage of numerical simulation the boundary element
method is used. In the final part of the paper the examples of computations are shown.
A Study on Development of Forming Roller for Miniature Metal Balls Manufacturing Process
Authors: Joe H.S. , Park J.S. , Kim Y.H.
Published: March 2009

According as the demand of miniature metal balls of various diameter increases,
processing property and a variety of coverage are important. In this study, especially an optimal
groove design of cutting roller was investigated for determining size and shape of metal ball in the
manufacturing system. The effects of radius of the groove and radius of the knife-edge of cutting
roller and the speed of roller as process parameters were calculated and analyzed. We applied data
of rigid-plastic FEM Simulation with DEFORM3D and ANSYS in basic design of equipment to
solve these issues, and checked processing parameter about metal balls manufacturing process that
use cutting process of metal wire stock in this research. This paper deals with the new improved
process of producing miniature STS316L steel balls continuously. Our first goal is to develop a
much more efficient equipment and a much more economical production process
Modelling the Dependence of Uniform Elongation on Grain Size
Authors: Liu W.J.
Published: March 2009

It has frequently been observed that the ductility or elongation of a material can
significantly be affected by its grain size. Poor ductility with low elongation has been found in
ultrafine-grained (UFG) steels when their grain size is smaller than a critical value. The so called
instability of plasticity is a well known drawback for UFG steels and has greatly prevented them from
wider application. Although the instability has been attributed to the lack of strain hardening capacity
of ultrafine-grained materials, its mechanism is still unclear. In this paper, a newly developed model
for predicting the dependence of uniform elongation on grain size is described, using which the
instability of plasticity in UFG steels can be explained. The model is based on a strain hardening
model for polycrystalline metals that was previously developed by the present author and was
modified in the present study to take the grain size effect into account. The uniform elongation
calculated using the model is in good agreement with that experimentally measured in two steels. It
was found that the elongation begins to decrease rapidly when the grain size is reduced to below 2μm
- a clear sign of the occurrence of the instability of plasticity.
Research and Development of Inconel 718 Type Superalloy
Authors: Xie Xi Shan , Dong Jian Xin , Zhang Mai Cang
Published: March 2009

Inconel 718(Ni-19Cr-18Fe-3Mo-5Nb-1Ti-0.5Al) nickel-base superalloy strengthened
mainly by Ni3Nb type γ″ and partially by Ni3Al type γ′ precipitation is today’s most widely used
superalloy in the world. China has paid special attention on Inconel 718 research and development.
Systematic long-term research project has been conducted in close cooperation among our university,
research institutes and factories. The goal of this long-term project is in 2 steps. First step is to
improve Alloy 718 to get high quality and the second step is for improving the alloy temperature
capability from 650oC to 680-700oC.
The basic idea for alloy improvement is still to keep the chemical composition in the range of
specification by small adjustment or control of minor elements, such as S, P, N, Si and Mg. The main
achievements are segregation control by adjustment of S, P, Si, control of N for cleanliness,
micro-alloying of Mg for grain boundary strengthening and control of low S and high P for stress
rupture life improvement.
Modification of Alloy 718 is based on structure stability study and its improvement in adjustment of
main second phase strengthening alloy elements Nb, Ti and Al in total amount and the ratios among
them. The goal is to achieve more stable second phase strengthening by control of alloy elements.
Experimental results show that the future of modified 718 alloys is very attractive to raise the
temperature capability improvement from 650oC to 680-700oC.
3D Coupled Thermomechanical Finite Element Analysis of Ultrasonic Consolidation
Authors: Huang C.J. , Ghassemieh E.
Published: March 2009

A 3-D coupled temperature-displacement finite element analysis is performed to study an
ultrasonic consolidation process. Results show that ultrasonic wave is effective in causing
deformation in aluminum foils. Ultrasonic vibration leads to an oscillating stress field. The
oscillation of stress in substrate lags behind the ultrasonic vibration by about 0.1 cycle of ultrasonic
wave. The upper foil, which is in contact with the substrate, has the most severe deformation. The
substrate undergoes little deformation. Apparent material softening by ultrasonic wave, which is of
great concern for decades, is successfully simulated. The higher the friction coefficient, the more
obvious the apparent material softening effect.
Direct Metal Laser Sintering Some Improvements of the Materials and Process
Authors: Dolinsek Slavko
Published: March 2009

For a comprehensive understanding of the direct metal laser sintering (DMLS) process and
for the successful introduction of this technology, some investigations related to the characteristics of
the powders and the individual sintered layers were therefore performed. Also possibilities of hard
coatings deposition for further improvements the wear and temperature resistance of tool inserts, and
investigations particularly focused into the industrial applications of DMLS tooling inserts are
presented.
Evolution of Microstructure during Hot Deformation of the PM Molybdenum Alloy TZM
Authors: Mrotzek T. , Hoffmann Andreas , Martin U. , Oettel H.
Published: March 2009

The molybdenum alloy TZM (Mo-0.5wt%Ti-0.08wt%Zr) is a commonly used structural
material for high temperature applications. For these purposes a high strength at elevated
temperatures and also a sufficient ductility at room temperature are being aimed. Preceding
investigations revealed the existence of subgrains in hot deformed TZM. It was observed that with
proceeding primary recrystallization and therefore with disappearance of subgrains the yield strength
drops almost to a level of pure molybdenum. It is being assumed that the existence of a dislocation
substructure has a pronounced effect on the yield strength of TZM. The aim of the present study was
to evaluate the subgrain and texture formation and also to estimate the dislocation arrangement within
subgrains during hot deformation. Hence, TZM rods were rolled to different degrees of deformation
at a temperature above 0.5 Tm. The microstructure of the initial material was fully recrystallized.
Texture formation, misorientation distributions and subgrain sizes were analyzed by electron
backscattering diffraction (EBSD). Mechanical properties were characterized by tensile tests at room
temperature and up to 1200°C. It was revealed, that with increasing degree of deformation a distinct
substructure forms and therefore yield strength rises. Consequently, the misorientation between
adjacent subgrains increases, their size decreases and a <110> fibre texture develops. To estimate the
influence of texture on strength of TZM the Taylor factors are calculated from EBSD data.
Formation of Ni57Zr20Ti22Pb1 Amorphous Powders by Mechanical Alloying
Authors: Lee Pee Yew , Hung S.S. , Jang Jason S.C. , Chen Giin Shan
Published: March 2009

In the current study, the amorphization behavior of mechanically alloyed
Ni57Zr20Ti22Pb1 powder was examined in details. The conventional X-ray diffraction
results confirm that the fully amorphous powders formed after 5 hours of milling. The
thermal stability of the Ni57Zr20Ti22Pb1 amorphous powders was investigated by differential
scanning calorimeter (DSC). As the results demonstrated, the glass transition temperature
(Tg) and the crystallization temperature (Tx) are 760 K and 850 K, respectively. The
supercooled liquid region is 90 K. The appearance of wide supercooled liquid region
may be mainly due to the Pb additions which cause the increasing differences in atomic size
of mechanically alloyed Ni57Zr20Ti22Pb1 powders.
Synthesis of Mono-Dispersed Fine Spherical Silver Powders by Chemical Reduction Method
Authors: Ahn Jong Gwan , Kim Dong Jin , Lee Jae Ryeong , Jung H.S. , Kim Byoung Gyu
Published: March 2009

The synthesis of spherical silver powders by chemical reduction method was investigated.
Conductive metal pastes to have good properties in adhesion, stability, and conductivity, it is very
important to control the purity, size, and shape of metal particles. In the present study, proper
methods to control the properties of micron sized metal powders for conductive pastes are
investigated. Chemical reduction method in aqueous solution was adapted to produce silver powder.
The effects of reaction time, concentration of reductant and additives, and stirring speed were
investigated, in experimental. Fine spherical silver powder of 0.5 to 3 ㎛ were synthesized from silver
nitrate solution with hydroquinone as a reducing additive by liquid phase method, and some variables
and reaction mechanism in conjunction with the particle morphology and size were studied.
Multiscale Molecular Dynamics Simulations of Nanostructured Materials
Authors: Tsuruta Kenij , Uchida Atsushi , Totsuji Chieko , Totsuji Hiroo
Published: March 2009

We present some attempts to simulate nanoscale phenomena, which involve different
length-scales and time-scales, using multiscale molecular-dynamics approaches. To simulate
realistically an impurity-segregated nanostructure, we have developed the hybrid quantum/classical
approach. The method can describe seamlessly both dynamical changes of local chemical bonding
and nanoscale atomic relaxations. We apply the method to hydrogen diffusion in Si grain boundary.
We find that the hydrogen is strongly trapped in (001)Σ5 twist boundary below 1000K, whereas it
starts diffusing along the grain boundary above 1000K. For long-time processes in nanostructure
formation, we apply the stochastic-difference-equation method to accelerate the simulations for
microstructure evolution. The method bridges the states separated by high-energy barriers in a
configuration space by optimizing an action, defined as an error accumulation along a reaction
pathway. As an example, a SDE simulation is performed for Cu thin-film formation via nanocluster
deposition. We show that the method can be applied effectively to search for the long-time process
which involves a rare event due to a large potential barrier between two atomic configurations.
Microstructural Characteristics of Cu-Fe-P Alloys Severely Deformed by Accumulative Roll Bonding Process
Authors: Lim Cha Yong , Han S.Z. , Lee Seong Hee
Published: March 2009

The accumulative roll bonding (ARB) process is one of the methods to refine the grain
size of metallic materials. The ARB process up to 8 cycles was performed for the pure Cu and Cu-
Fe-P (PMC-90) alloy at ambient temperature under no lubricant conditions. In the pure Cu, the
nano-sized grains were formed after third cycle with an average grain size of 200nm. Once the 200
nm grains formed, further reduction in the grain size was not observed up to the 8 ARB process
cycles. On the other hand, the formation of the stable nano-sized grains in PMC-90 alloy was
retarded compared to the pure Cu due to the alloying elements. For both alloys, the tensile strength
values increased drastically in the initial stage of ARB process. The tensile strength values of both
alloys tended to saturate after the third ARB process cycle. The tensile elongation value greatly
decreased by 1 cycle of ARB process due to the strain hardening. After the third cycle of ARB
process, each alloy showed a gradual increase in tensile elongation due to the dynamic recovery.
For PMC-90 alloy, the strength value is higher than that of OFC due to addition of the alloying
elements.
An Alternative Constitutive Equation for Superplasticity
Authors: Naik Buddhisagar
Published: March 2009

Different models have been put forward to explain superplasticity. Most of the models
predict the independency of activation energy (Q) on stress. Superplasticity is observed in region II
of creep curve (logε Vs σ/E). The most commonly considered mechanism for superplastic flow
involves Grain Boundary Sliding (GBS), and it is necessary for an accommodation process to
accompany GBS. The accommodation process might be grain boundary migration, recrystalisation,
diffusional flow or some dislocation slip process. But the Arrhenius type of equation given by
Becker gives the dependency of activation energy on stress. Here in this work we have considered
this equation and relation between Q and σ is found out using genetic algorithm. The present model
development studies the parameter optimization, where parameters appearing in the stress and
energy relationship equation e.g. relationship between Q(σ) and σ for the Q(σ) equation given in
present work as well as pre-exponential factors are optimized with the objective function being the
error minimization of model predicted values and experimental data of strain are available from
open literature.