bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of (Ferrite+Cementite) Microduplex Structure by Warm Deformation in High Carbon Steels
Authors: Furuhara Tadashi , Yamaguchi Takuto , Furimoto Shoji , Maki Tadashi
Published: March 2009

The microstructure change by warm deformation in high-carbon steels with different
initial ferrite (α) + cementite (θ) duplex microstructures has been examined. Three kinds of initial
structures, i.e., pearlite, α+spheroidized θ and tempered martensite, were prepared using
Fe-0.8C-2Mn and Fe-1.0C-1.4Cr alloys and compressed by 30-75% at 973K at a strain rate of
5x10-4 s-1. Equiaxed fine α grains, approximately 2μm in diameter and mostly bounded by
high-angle boundaries, are formed with spheroidized θ by dynamic recrystallization during
compression of the pearlite by 75%. When the (α+θ) duplex structure containing spheroidized θ
was deformed, the original α grains become elongated and only subgrains are formed within them
by dynamic recovery. For the tempered martensite, equiaxed α grains similar to those in the
deformed pearlite were obtained after 50% compression. This indicates that the critical strain
needed for the completion of dynamic recrystallization of α is smaller for the tempered martensite
than for the other structures.
Thermo-Mechanical Fatigue Behaviour of the Gamma-Titanium Aluminide TNB-V5 with Near-Gamma Microstructure
Authors: Roth M. , Biermann Horst
Published: March 2009

The efficiency of aircraft and industrial gas turbines and combustion engines depends on
the maximum operation temperature and, therefore, on the properties of the commercial high
temperature materials. In the temperature range 500°C to 750°C γ-titanium aluminides especially
alloys of the third generation represent an attractive alternative to the established nickel-base
superalloys which have the double density. Due to superimposed cyclic thermal and cyclic
mechanical loadings during start-up and shut-down operations structural components in gas turbines
and combustion engines may not only be exposed to isothermal but also to thermo-mechanical fatigue
(TMF). In this study the cyclic deformation and fatigue behaviour under thermo-mechanical load of
the γ-TiAl alloy TNB-V5 with near-gamma microstructure is evaluated. To set a fatigue-life relation
strain-controlled thermo-mechanical fatigue tests were carried out with two different strain ranges,
different temperature-strain cycles and different temperature ranges from 400°C to 800°C. Additional
low-cycle fatigue (LCF) tests were performed at 400°C, 600°C and 800°C for comparison. Cyclic
deformation curves, stress-strain hysteresis loops and fatigue lives of the tests are presented. The
shortest fatigue lives are always observed in out-of phase (OP) tests, the longest in in-phase (IP) tests.
Clockwise-diamond (CD) and counter-clockwise diamond (CCD) testing yield similar fatigue lives
intermediate between those of OP and IP tests. For a general life prediction the double-logarithmic
plot of the damage parameter by Smith, Watson and Topper vs. fatigue life is well suitable.
Grain Boundary Precipitation and Tensile Ductility of Fe-Mn-Ni Alloys
Authors: Heo Yoon Uk , Mun Seung Ho , Lee Hu Chul
Published: March 2009

The mechanism of grain boundary embrittlement and the improvement of the tensile
ductility afforded by alloy addition or heat treatment was investigated in an Fe-Mn-Ni alloy. The
precipitation of θ-MnNi intermetallic particles was observed at the prior austenite or interlath
boundaries during the aging treatment and this was believed to be responsible for the grain
boundary embrittlement of these alloys. After prolonged aging or aging at higher temperatures
above 520°C, these metastable intermetallic particles were transformed into the thermodynamically
stable austenite phase, thereby leading to the recovery of the grain boundary strength. The addition
of Mo caused the grain boundary precipitate to be changed to austenite and resulted in a significant
improvement in the tensile ductility after aging.
New Phases in the Mg-Al-Sr System
Authors: Medraj Mamoun , Parvez M.A. , Essadiqi Elhachmi , Li Jian
Published: March 2009

This work presents experimental investigation of 14 different alloys with differential
scanning calorimetery (DSC), scanning electron microscopy/energy dispersive spectrometer
(SEM/EDS) analysis, quantitative electron probe micro-analysis (EPMA) and X-ray diffraction
(XRD) techniques to identify the phases in the Mg-Al-Sr system and to determine their compositions.
DSC has permitted real time measurement of the phase changes involved in these systems. The
temperature ranges for the phase transformations and enthalpy of melting and enthalpy of formation
of the compounds are reported. Comparison between these results and the thermodynamic findings
has been discussed. The microstructure of the Mg-Al-Sr-based alloys is primarily dominated by (Mg)
and (Al4Sr). The plate-like structure has been identified as Al4Sr. A new ternary intermetallic with
chemical composition of 69.9 ± 1.5 at.% magnesium, 19.3 ± 2.0 at.% aluminum and 8.7 ± 0.6 at.%
strontium has been identified in three different alloys. This phase was characterized as a large
precipitate. Three ternary solid solutions have been observed. The solubility ranges of Al in Mg38Sr9
and Mg17Sr2 are 12.5 and 8.5 at.%, respectively, whereas the solubility of Mg in Al4Sr compound is
found to be 23 at.% in the investigated samples. Further, Mg was found to dissolve 11.4 at.% Al at
room temperature.
Development of Conductive Anodic Oxidation Coatings on AZ91D Magnesium Alloy
Authors: Hino Makoto , Murakami Koji , Hiramatsu Minoru , Saijo Atsushi , Kanadani Teruto
Published: March 2009

AZ91D magnesium alloy was anodized in an electrolytic solution with phosphate as the
main component. The conductivity and structure of the obtained coatings were examined. The
anodic oxidation coatings are found to be composed of Mg, O, Al, and P. By controlling the
phosphorus content, conductive coatings could be formed with surface resistivities of 0.2 ' or less.
XRD analysis and TEM observations reveal that the structure of the conductive coatings is
amorphous.
Texture Evolution during Uniaxial Compression of Hot-Rolled AZ31 Mg Alloy
Authors: Choi Shi Hoon , Kim B.J. , Kim S.I. , Joon U.S.
Published: March 2009

Uniaxial compression tests on hot-rolled AZ31 Mg alloy were carried out at 200°C. In
order to investigate the evolution of texture during plastic deformation, cylindrical specimens were
compressed to the rolling and normal directions. Experimental investigation reveals that work
hardening and texture evolution are strongly dependent on the loading direction. The occurrence of
deformation twinning was revealed by the observation of microtexture using electron backscatter
diffraction (EBSD). A visco-plastic self-consistent (VPSC) polycrystal model was used to simulate
the texture evolution during the uniaxial compression. The texture evolution induced by
crystallographic slip and deformation twinning can be explained by the relative activity of each
deformation modes.
Integral Foam Molding - A New Process for Foamed Magnesium Castings
Authors: Hirschmann Markus , Körner Carolin , Singer Robert F.
Published: March 2009

Integral foam molding (IFM) is an economical near net-shape technology to produce
monolithic castings with solid skin, foamed core and continuous density transition between skin and
core. It was developed for polymers in the 1960s. But it took about ten years to optimize the
molding technique and the quality of the polymer integral foam parts to a marketable stage.
Meanwhile, polymer integral foam parts are established in a lot of commercial applications. The
situation is completely different for metals. The first attempts to produce metal integral foam parts
were made only a few years ago. A cost effective injection molding technique for magnesium
integral foam was developed at the WTM-Institute in Erlangen, Germany. The low-cost production
in combination with the integral foam properties low density, high weight specific bending stiffness
and remarkable damping capacity is very promising. At the beginning we produced only parts with
simple shape, for example plates. But if we think about commercial applications, more complex
parts with a three-dimensional shape are required. The focus of this paper is on new developments
concerning the production of magnesium integral foam parts with complex shape like a casing
cover or a door handle.
Processing of Closed-Cell Magnesium Foams
Authors: Kitazono Koichi , Kikuchi Yusuke , Sato Eiichi , Kuribayashi Kazuhiko
Published: March 2009

Lightweight metallic foams are an attractive material having excellent energy absorption
and acoustic damping. The density of magnesium is the smallest among structural metallic materials,
and is about two third of the density of aluminum. It is, however, difficult to produce magnesium
foams by conventional process because of their chemical activity. This paper provides a novel
manufacturing process of magnesium foams. Accumulative diffusion-bonding process can produce
a magnesium matrix composite (preform) containing titanium hydride (TiH2) particles as a blowing
agent. Foaming tests of three magnesium alloys, AZ31, AZ91 and ZA146, revealed that low solidus
temperature is effective to produce fine cell morphology. Chemical composition is significantly
important to optimize the cell morphology of magnesium foams.
Mechanical Response of Porous Copper Manufactured by Lost Carbonate Sintering Process
Authors: Tao X.F. , Zhang Li Ping , Zhao Y.Y.
Published: March 2009

This paper investigated the mechanical response of porous copper manufactured by LCS
under three-point bending and Charpy impact conditions. The effects of the compaction pressure
and K2CO3 particle size used in producing the porous copper samples and the relative density of the
samples were studied. The apparent modulus, flexural strength and energy absorption capacity in
three-point bending tests increased exponentially with increasing relative density. The impact
strength was not markedly sensitive to relative density and had values within 7 – 9 kJ/m2 for the
relative densities in the range 0.17 – 0.31. The amount of energy absorbed by a porous copper
sample in the impact test was much higher than that absorbed in the three-point bending test,
impling that loading strain rate had a significant effect on the deformation mechanisms. Increasing
compaction pressure and increasing K2CO3 particle size resulted in significant increases in the
flexural strength and the bending energy absorption capacity, both owing to the reduced sintering
defects.
Fabrication of Lotus-Type Porous Copper-Aluminum Alloy by Unidirectional Solidification in Hydrogen Atmosphere
Authors: Hyun Soong Keun , Awadu Tsuyoshi , Ikeda Teruyuki , Nakajima Hideo
Published: March 2009

Lotus-type porous Cu-5at.%Al alloy whose elongated pores are aligned in one direction
was fabricated by unidirectional solidification in pressurized hydrogen gas atmosphere. The
porosity of the Cu-Al alloy was higher than that of pure copper under the same fabrication
conditions because of difference in hydrogen solubility. The pore structure was not round shape
because the directional pore growth was interrupted with dendrite arms formed during the
solidification; the pores grew to detour the obstacle of the dendrite arms.
Computational Relationship of Deformation Behavior and Materials Strength of Amorphous Alloys to Short-Ranged Local Structures
Authors: Shibutani Yoji , Wakeda Masato , Ogata Shigenobu , Park Jun Young
Published: March 2009

CuxZr1-x (x=0.30~0.85) binary amorphous alloy models were constructed using molecular
dynamics simulations. In order to characterize the short-ranged local structures and the free volume
of the whole cell, Voronoi polyhedral analyses were performed for their initial states and also for
the deformed states. Both geometrical and physical factors are intimately related to each other and
exhibit a large influence on mechanical properties. The elastic properties of shear modulus and bulk
modulus tend to increase as the free volume decreases. The Poisson’s ratio, which is related to the
glass fragility, increases as the free volume. However, the relation among three elastic properties
obtained from the continuous mechanics of the isotropic body does not hold. Also, the maximum
stress in the finite deformation drastically decreases with increasing free volume content.
Elastic Properties of Cu-Based Bulk Metallic Glass around Glass Transition Temperature
Authors: Tarumi R. , Ogi H. , Hirao M. , Ichitsubo T. , Matsubara Eiichiro , Saida Junji
Published: March 2009

Temperature dependent elastic constants Cij(T) of Cu60Hf30Ti10 bulk metallic glass
(BMG) have been investigated in a MHz frequency range using electromagnetic acoustic resonance
(EMAR) up to 823 K. At room temperature, the BMG showed high Poisson’s ratio ν arising from
low shear modulus G compared with that of constitutive crystalline elements. With increasing
temperature, G showed usual linear temperature dependence while it suddenly drops around glass
transition temperature, Tg. Within a framework of quasiharmonic approximation, Grüneisen
parameter γ around Tg is estimated to be 10. This extremely large γ indicates the high
anhramonicity of long wavelength limit acoustic mode phonon in the supercooled liquid state.
The unusual elastic behavior can be interpreted on the basis of heterogeneous microstructure.
Plastic Deformation Behavior of Bulk Metallic Glass Composite Containing Spherical Ductile Crystalline Precipitates
Authors: Sun G.Y. , Chen G. , Chen Guo Liang
Published: March 2009

Mechanical alloying (MA), super cooling process, etc. have been used to prepare
amorphous phases, metastable solid solutions, nanocrystals, and so on. It is important to consolidate
these powders for evaluating the physical properties, and for applications. On the other hand, shock
compression can be used as an effective consolidation method for metastable material powders
without recrystallization or decomposition. We had prepared metastable transition-metal system
bulk alloys and compounds (Fe-Co, Fe-Cu, Fe-W, Co-Cu, Sm-Fe-N systems, etc) by using MA and
shock compression. The Fe-Cu and Co-Cu metastable solid solutions showed a fit curve to the
Slater-Pauling one. The Co-Cu metastable solid solution bulk alloy showed a magneto-resistance.
The Fe-Co fine-grained bulk alloys show the higher coeicivity than that of molten alloy. In this
paper, the preparation and magnetic properties of the metastable alloys (Fe-Co, Fe-Cu, Co-Cu
systems) are reviewed, and the applications to materials science and engineering are discussed.
Glass Structure Control of Zr-TM-Al (TM: Cu, Ni and Co) BGAs with Small Additive Elements
Authors: Yokoyama Yoshihiko , Inoue Akihisa
Published: March 2009

The degree of amorphousness of the cast glassy sample is evaluated by free volume,
which can be roughly estimated by density. The glass structural difference of cast glassy samples
is mainly originated to the difference of those cooling rates. In order to clarify the degree of
amorphousness, we use the volume change during annealing just below glass transition temperature
(Tg) in this study. Therefore the volume change has close relation with free volume. We tried to
control the excess free volume in Zr-TM-Al (TM: Cu, Ni and Co) bulk glassy alloys (BGAs) using
small additive element. We found the elements; Pd, Ag, Pt and Au, whose outer d-electrons are
filled up, are effective to increase the volume change/free volume in Zr-Cu-Al BGAs. The
relationship between the Young’s modulus and volume change indicates the existence of two
groups. The difference between them might be originated to the difference in glass structures.
Icosahedral Order in Supercooled Liquids and Glassy Alloys
Authors: Shimono Masato , Onodera Hidehiro
Published: March 2009

Formation of the icosahedral order in supercooled liquids and glassy phases is
investigated for a model alloy system by using molecular dynamics simulations. The simulation
results show that the short-range icosahedral order grows in the supercooled liquids as well as in
the glassy phases. Structural analyses reveal that the icosahedral clusters form a network in which
the clusters are connected via the pentagonal-bicap sharing. Geometrical property of the network
formed by the icosahedral clusters is an origin of medium-range order in the glassy phases
Mechanical Properties of an Amorphous or Partially Crystallized Zirconium Based Metallic Glass
Authors: PELLETIER Jean-Marc , Gravier Sébastien , Blandin Jean Jacques
Published: March 2009

The effect of partial crystallization on the mechanical properties of a Zr based bulk
metallic glass (Vitreloy 1) is investigated. Viscoelastic properties are studied by mechanical
spectroscopy in large frequency and temperature ranges, both below or above the glass transition
temperature (Tg), whereas viscoplastic properties are investigated by compression tests . To study
the interaction between crystallization and mechanical properties at high temperature,
nanocomposites are produced thanks to appropriate heat treatments. Formation of nanocrystalline
particles induces an increase of the storage elastic modulus, especially in the glass transition range,
where this modulus is very low in the amorphous material. It also results in a decrease of the loss
elastic modulus, corresponding to a decrease of the atomic mobility. Finally, partial crystallization
induces very large hardening revealed by the compression tests but the hardening extent depends
strongly on the applied strain rate.
Relaxation Kinetics of Bulk Metallic Glasses below Glass Transition Temperature
Authors: Haruyama Osami , Yokoyama Yoshihiko , Kimura Hisamichi , Inoue Akihisa , Nishiyama Nobuyuki
Published: March 2009

The free volume relaxation just under the glass transition region was investigated by the
high-resolution density measurement using the bulk metallic glasses with the compositions of
Pd40Ni40P20 and Zr55Cu30Ni5Al10. The relaxation process was well described by a stretched
exponential function with Kohlrausch exponent values less than unity. The reduced free volumes in
an as-quenched state were estimated as 0.0117 and 0.0353 for Pd40Ni40P20 glass and Zr55Cu30Ni5Al10
glass, respectively. The specific heat curves Cp(T) for Pd42.5Cu30Ni7.5P20 alloy were obtained for the
supercooled liquid, the equilibrium liquid and the crystallized alloy. The isenthalpic Kauzmann
temperature TKH and isentropic Kauzmann temperature TKS were estimated as 471 K and 522 K,
respectively, from the specific heat data.
Superplastic Nanoforging of Pt-Based Metallic Glass with Dies of Zr-BMG and Glassy Carbon Fabricated by Focused Ion Beam
Authors: Saotome Yasunori , Okaniwa Suguru , Kimura Hisamichi , Inoue Akihisa
Published: March 2009

This paper introduces a technique for fabricating nano-structures through
super plastic nano-forging of metallic glass using nano-scale dies that are fabricated
by a focused-ion beam (FIB). FIB-machining characteristics of glassy carbon and
Zr-based metallic glass have been studied and are useful for fabricating nano-scale
dies because of the isotropic homogeneity of their amorphous structures. We used the
dies to nano-forge Pt48.75Pd9.75Cu19.5P22 metallic glass. The thin foil specimens were
heated in a small furnace and compressively loaded in a small vacuum chamber. Dies,
a die-forged 1μm-diameter micro-gear, and both 800 and 400nm periodic
nano-structures for optical applications were demonstrated. We observed the effects
of thermal expansion and contact angle between the working material and the die
materials on nano-formability. Metallic glasses are highly useful as materials for
nano-imprinting and as die materials for FIB nano-machining.
Numerical Analysis of Test Methods for Evaluating Shear Strength of Ceramic Composite Joints Using Interface Element
Authors: Serizawa Hisashi , Lewinsohn Charles , Singh Mrityunjay , Murakawa Hidekazu
Published: March 2009

As examples of the most typical methods to determine the shear strength of SiC/SiC
composite joints, the asymmetrical four point bending test of butt joined composite, the tensile test
of lap joined composite and the compressive test of double-notched composite joint were analyzed
by using finite element method with the interface element. From the calculation results, it was
found that the shear strength in the asymmetrical bending test was controlled by both the surface
energy and the shear strength at the interface regardless of their combination although the strength
in the tensile test or the compressive test was governed by the surface energy when the shear
strength was large. Also, it was revealed that the apparent shear strength of the composite joint
obtained experimentally might be affected by the combination of the surface energy and the shear
strength at the interface.
Application of Local Approach to Hydrogen Embrittlement Fracture Evaluation of High Strength Steels
Authors: Takagi Shusaku , Terasaki Satoshi , Tsuzaki Kaneaki , Inoue Tadanobu , Minami Fumiyoshi
Published: March 2009

A new method for evaluating the hydrogen embrittlement (HE) susceptibility of ultra high
strength steel was studied in order to propose a new method for assessing the delayed fracture
property. The material used was 1400MPa tempered martensitic steel with the chemical composition
0.40C-0.24Si-0.81Mn-1.03Cr-0.16Mo(mass%). The local approach originally used for evaluating the
brittle fracture property was applied to HE susceptibility assessment after modifying the method to
include the effect of hydrogen content. Critical HE data used in the modified local approach was
obtained by a stepwise test in which alternating processes of stress increase and stress holding were
repeated until the specimen fractured. The specimen used in the stepwise test was 10 mm in diameter
and the stress concentration factor was 4.9. Assessment of HE susceptibility for specimens with other
dimensions entailed the use of a critical hydrogen content for failure, Hc, representing the maximum
hydrogen content among the unfractured specimens in the HE test with constant loading. Matters to
be noted for obtaining the material parameters are discussed.
Effect of Dispersoids on Softening Behavior in Cu-Fe-P Alloys for Lead Frames
Authors: Aruga Yasuhiro , Hara Naohiro , Kajihara Katsura
Published: March 2009

The effect of the amount of dispersoids on softening behavior and recrystallized
microstructure of Cu-Fe-P alloy was examined by the extracted residue analysis method. The
degrees of contribution of larger particles (larger than 1μm in an average diameter) and smaller
ones (less than 0.1μm) to the softening behavior were considered in the quantitative aspect,
respectively. It was found that the change of the order of 10-1mass% in the amounts of both
particles has a great effect on softening behavior. The difference in the amount of fine particles
changes recrystallized grain size distributions at similar hardness. In the specimen with a small
amount of fine particles, coarse grains and wide distribution of grain size were observed after
annealing. As a result, it was revealed that fine and homogeneous recrystallized microstructure was
obtained due to just 0.35mass% of fine partcles, even if the amount of large particles increased.
Effect of Dislocation Distribution on the Yielding of Highly Dislocated Iron
Authors: Takaki Setsuo , Fujimura Y. , Nakashima Koichi , Tsuchiyama Toshihiro
Published: March 2009

Yield strength of highly dislocated metals is known to be directly proportional to the
square root of dislocation density (ρ), so called Bailey-Hirsch relationship. In general, the
microstructure of heavily cold worked iron is characterized by cellar tangled dislocations. On the
other hand, the dislocation substructure of martensite is characterized by randomly distributed
dislocations although it has almost same or higher dislocation density in comparison with heavily
cold worked iron. In this paper, yielding behavior of ultra low carbon martensite (Fe-18%Ni alloy)
was discussed in connection with microstructural change during cold working. Originally, the
elastic proportional limit and 0.2% proof stress is low in as-quenched martensite in spite of its high
dislocation density. Small amount of cold rolling results in the decrease of dislocation density from
6.8x1015/m-2 to 3.4x1015/m-2 but both the elastic proportional limit and 0.2% proof stress are
markedly increased by contraries. 0.2% proof stress of cold-rolled martensite could be plotted on
the extended line of the Bailey-Hirsch equation obtained in cold-rolled iron. It was also confirmed
that small amount of cold rolling causes a clear microstructural change from randomly distributed
dislocations to cellar tangled dislocations. Martensite contains two types of dislocations;
statistically stored dislocation (SS-dislocation) and geometrically necessary dislocation
(GN-dislocation). In the early deformation stage, SS-dislocations easily disappear through the
dislocation interaction and movement to grain boundaries or surface. This process produces a
plastic strain and lowers the elastic proportional limit and 0.2% proof stress in the ultra low carbon
martensite.
Neutron Diffraction Profile Analysis to Determine Dislocation Density and Grain Size for Drawn Steel Wires
Authors: Ryufuku S. , Tomota Yo , Shiota Y. , Shiratori T. , Suzuki Hiroshi , Moriai Atsushi
Published: March 2009

Dislocation density and crystallite size of steel wires with various carbon
concentrations and drawing strains were determined by profile analyses for neutron diffraction
profiles. The density is found to increase while the size decreases with increasing of carbon
concentration and/or drawing strain. Both of the Bailey-Hirsch relation and Hall-Petch relation hold
for the present results to suggest that these two are not independent., i.e., indicating an identical
strengthening mechanism from a different point of view.
3-Dimensional Characterization of Polycrystalline Bulk Materials Using High-Energy Synchrotron Radiation
Authors: Lienert Ulrich , Almer Jonathan , Jakobsen Bo , Pantleon Wolfgang , Poulsen Henning Friis , Hennessy D. , Xiao C. , Suter R.M.
Published: March 2009

The implementation of 3-Dimensional X-Ray Diffraction (3DXRD) Microscopy at the
Advanced Photon Source is described. The technique enables the non-destructive structural
characterization of polycrystalline bulk materials and is therefore suitable for in situ studies during
thermo-mechanical processing. High energy synchrotron radiation and area detectors are employed.
First, a forward modeling approach for the reconstruction of grain boundaries from high resolution
diffraction images is described. Second, a high resolution reciprocal space mapping technique of
individual grains is presented.
Kinetic Features of Solid-State Reactive Diffusion between Au and Sn-Base Solder
Authors: Kajihara M. , Takenaka T.
Published: March 2009

The kinetics of the solid-state reactive diffusion between Au and Sn was experimentally
observed using Sn/Au/Sn diffusion couples prepared by a diffusion bonding technique. The
diffusion couples were isothermally annealed at a temperature of T = 453 K. Due to annealing, AuSn,
AuSn2 and AuSn4 compound layers are formed at the interface in the diffusion couple. The
experimental results were used to evaluate quantitatively the effect of Ni on the growth of the Au–Sn
compounds. The evaluation indicates that the addition of Ni into Sn between 1 and 5 mass%
accelerates the growth of the Au–Sn compounds at T = 433–473 K.
Current Status and Next Generation Advances in Fuel Cell Research and Development
Authors: Wilkinson David
Published: March 2009

Significant technical challenges still remain today for the fuel cell in a number of areas
including reliability, durability, cost, operational flexibility, technology simplification and
integration, fundamental understanding and life cycle impact. New advanced materials and
associated innovative engineering design will be required to close these technical gaps. This paper
provides a perspective on fuel cell technology today, research and development directions,
challenges going forward, and a future view of the fuel cell.
An Analytic Model for Predicting Roll Force in Billet Rolling Process with Vertical Stands and Horizontal Stands Mounted
Authors: Byon Sang Min , Lee Young Seog
Published: March 2009

In this paper, we present an analytic approach for the prediction of roll force to be
applicable to the billet rolling process which consists of a series of horizontal stands and vertical
stands. The approach is based on the deformation shape and employs the assumption that the
deformation homogeneously occurs in three directions. Strain and strain rate are calculated by the
geometric relationships between those components and the prescribed deformation functions. By
integrating the stress components along the rolling direction, roll force is finally obtained. The
prediction accuracy of the proposed model is examined through comparison experimentally mesured
roll force with computed ones.
Application of the Shape Sensitivity Analysis in Numerical Modelling of Solidification Process
Authors: Mochnacki Bohdan , Majchrzak Ewa
Published: March 2009

The methods of sensitivity analysis allow to estimate the influence of parameters
determining the geometrical, physical, boundary and initial conditions on the course of thermal
processes in the system considered. In this paper the possibilities of shape sensitivity analysis
application (SSA) in the thermal theory of foundry processes are discussed. In particular, the direct
approach is presented because it seems that for practical applications this variant of sensitivity analysis
is more effective. The theoretical base of SSA is presented in chapters 1 and 2, next the practical
aspects of the method are discussed. In the final part of the paper the examples of computations can be
found.
Prealloyed Cu-Fe Powder Materials
Authors: Llorca-Isern Nuria , Laborde I. , Mirabet X. , Molera P. , Roca Antoni
Published: March 2009

Mechanical alloying (MA) is one of the most appropriate severe plastic deformation
processes applied to powders in order to obtain good mixing, new different systems or alloys and /
or to reduce particles grain size from the starting powders. In the present work, MA was used to
obtain prealloyed powders of Cu-Fe base alloys suitable for subsequent sintering. Mechanical
alloying process parameters have been optimised to reduce container and balls contamination in dry
and inert atmosphere conditions. For safe final powder manipulation, the final aggregate size
requirement needed to be kept in the microscopic scale. The microstructural results showed that the
components of the original powders were intimately combined resulting in alloyed aggregates
suitable for sintering and for mixing to other hard materials to obtain composites. The materials
selection for container and balls is critical in order to avoid contamination. In the present work, no
contamination was detected in the final processed particles. Consolidation of these powders was
carried out as well as calorimetric tests for studying their stability.
Effect of Manufacturing Methods on Structure and Properties of the Gradient Tool Materials with the Non-Alloy Steel Matrix Reinforced with the HS6-5-2 Type High-Speed Steel
Authors: Kloc A. , Dobrzański Leszek Adam , Matula G. , Torralba José Manuel
Published: March 2009

Investigations carried out referred to obtaining material based on the high-speed steel and
non-alloy steel. The conventional powder metallurgy method was used for manufacturing these
materials, consisting in compacting the powder in the closed die and sintering it next, the isostatic
pressing method, and the modern pressureless forming powder metallurgy. Forming methods were
developed during the investigations for high-speed and non-alloy steel powders, making it possible
to obtain materials with three layers in their structure. Investigations included determining the
sintering conditions, and especially the temperature and treatment cycle, as well as examining the
selected mechanical properties. It was found out, basing on the comparison of structures and
properties of test pieces made with the pressureless forming method, as well as with the isostatic
pressing and pressing in the closed die, with further sintering, that in structures of all examined test
pieces in the sintered state fine carbides occurred distributed homogeneously in the high-speed steel
layer. It was noticed, that increase of the sintering temperature, regardless of the manufacturing
method, results in the uncontrolled growth and coagulation of the primary carbides and melting up
to forming of eutectics in layers consisting of the high-speed steel. It was found out basing on the
microhardness tests that hardness of test pieces both those pressureless formed, compacted in the
closed die, and isostatically cold pressed and sintered grows along with the sintering temperature. It
was also noted that the sintering temperature range is bigger in case of the pressureless formed
materials.
Fabrication of Micro Porous Aluminum by Powder Sintering
Authors: Xie Zhen Kai , Yamada Yasuo , Banno Takumi
Published: March 2009

Highly porous materials with a cellular structure are known to have many interesting
combinations of physical and mechanical properties, such as very low specific weight combined
with high thermal conductivity. However, when the pore size of the foam metal grows, the strength
maintenance is scarce because the array of the pore is not uniform. In the present work, micro
porous aluminum with porosities between 5% and 50% and pore sizes of 20～50 μm was produced
by applying the powder metallurgical technique, i.e. by sintering the aluminum metal powders and
PMMA powder mixture at 913 K. The effect of sintering temperature on the compressive properties
of porous aluminum was investigated. The effects of particle size and fraction of space holding
particle and metal powder on the porosity pore size and mechanical properties of porous sintered
specimens were mainly investigated. The pore size of porous aluminum can be controlled by
changing the PMMA powder diameter. The results show the fabrication of the micro porous
aluminum with middle porosity and high strength is possible.
Progress and Current Status in Research on Nanostructured Cu-Ag Microcomposites for Conductor Wires
Authors: Meng Liang , Liu J.B.
Published: March 2009

An overview of the microstructure evolution, mechanical properties, electrical conductivity and microalloying
is presented and some further research fields are suggested for Cu-Ag microcomposites. The nanostructures of
filamentary morphology in these microcomposites can be obtained by heavy deformation. Both the mechanical and
electrical properties depend upon the material composition, strain degree, intermediate heat treatments and final
annealing processes. These factors strongly affect the phase proportion, microstructure morphology, precipitate volume,
hardening level and filamentary distribution. Optimum technology of materials preparation makes the microcomposites
possess high strength and conductivity. Some third constituents added to the alloys improve the strength but generally
decrease the conductivity. It is considered that relative mechanisms and processes should be further investigated for the
development and application of the microcomposites.
Deformation Mechanism Map of Nanocrystalline Metallic Materials
Authors: Kim Hyoung Seop
Published: March 2009

In this study, a deformation mechanism map of metallic nanocrystalline materials (NCMs)
using the phase mixture model is proposed. It is based on recent modelling that appears to provide a
conclusive description of the phenomenology and the mechanisms underlying the mechanical
properties of NCMs. The proposed models adopted the concept of a ‘phase mixture’ in which the
grain interior and the grain boundaries are treated as separate phases. The volume fraction of this grain
boundary ‘phase’ may be quite appreciable in a NCM. Based on the theoretical model that provides an
adequate description of the grain size dependence of plasticity covering all grain size range from
coarse down to the nanoscale, the tensile deformation response of NCMs, especially focusing on the
deformation mechanisms was investigated. The deformation mechanism map is newly proposed with
axes of strain rate, grain size and temperature.
Nanostructuring a Zr-Hf Alloy via Large Strain Rolling
Authors: Pérez-Prado Maria Teresa , Salort F. , Jiang Ling , Ruano Oscar , Kassner Michael E.
Published: March 2009

A coarse grained Zr-Hf alloy has been subjected to one rolling pass with different
thickness reductions ranging from 10% to 80%. Rolling was performed at three temperatures:
300°C, room temperature (RT) and liquid nitrogen temperature (-196°C). It has been found that,
with increasing strain per pass, i.e., with increasing strain rate, the deformation mechanism changes
from twinning to dislocation slip. The minimum strain per pass necessary to trigger the transition in
deformation mechanism decreases with decreasing temperature. High strain, high strain-rate
deformation leads to the development of an ultrafine grained structure. Simultaneously, a basal type
rolling texture forms. At the higher temperatures (RT and above) a recrystallization texture
component is also present. Thus, nanostructuring of this Zr-Hf alloy during severe rolling is
attributed to a combination of grain subdivision by the formation of geometrically necessary
boundaries and to nucleation and growth phenomena taking place as a consequence of rapid
adiabatic heating.
Coarse Second Phase Particle Size Distribution of UFG Al Alloys Processed by Severe Plastic Deformation: Effect on Cavitation during Superplastic Deformation
Authors: Park Kyung Tae , Lee Eui Gil , Nam Won Jong , Lee Yong Shin
Published: March 2009

Two commercial Al alloys having different second phase particle distributions were
subjected to severe plastic deformation (SPD) via equal channel angular pressing with or without
subsequent cold rolling, and the effect of such SPD on the particle size distribution of the alloys was
investigated. The particles larger than ∼ 3 μm were fragmented into several smaller ones by SPD.
Contrarily, those smaller than ∼ 3 μm were hardly broken up by SPD but their distribution became
more uniform. Along with these findings and the theoretical models for cavity nucleation at second
phase particles, the cavitation behavior of ultrafine grained Al alloys during low temperature or
high strain rate superplastic deformation was discussed.
Mechanical Properties of Al-5.7wt% Ni Eutectic Alloy Severely Deformed by Equal-Channel Angular Pressing
Authors: Watanabe Yoshimi , Zhang Zuo Gui , Sato Hisashi , Inamura Tomonari , Hosoda Hideki
Published: March 2009

In this study, an Al-5.7wt% Ni eutectic alloy was subjected to severe plastic
deformation (SPD) by an equal-channel angular pressing (ECAP) technique. ECAP technique was
carried out by using two strain introduction methods, route BC and route A, at a temperature. It is
found that the Al-Ni eutectic alloy specimens after ECAP technique by route BC and route A
methods have very different microstructures which affected strongly the tensile properties of the
specimens. Namely, after ECAP technique by route BC method, the fine Al3Ni dispersoids of
about 300 nm homogeneously dispersed in α-aluminum matrix and the samples appeared no clear
anisotropic in tensile properties, while the eutectic textures containing α-Al and Al3Ni fibrous
dispersoids have highly anisotropy distribution and are proved to have significant anisotropy tensile
properties after ECAP technique by route A method. Results of Young’s modulus and
simultaneous internal friction measured by dynamic mechanical analysis (DMA) were also
presented. Based on the experimental results, the fracture mechanism during tensile process of the
Al-Ni eutectic alloy by different strain induction methods was discussed.
Hot Working of High-Purity Nickel-Niobium Alloys
Authors: Montheillet Frank , Girard S. , Desrayaud Christophe , Semiatin S. Lee , Le Coze J.
Published: March 2009

The present work deals with the influence of niobium in solid solution on the dynamic
recrystallization of pure nickel. High-purity nickel and two model nickel-niobium alloys were
deformed to large strains via torsion at temperatures between 800 and 1000°C. Niobium additions
considerably increased the flow stress, while they lowered the strain-rate sensitivity and increased
the apparent activation energy. EBSD of the steady-state microstructures revealed strong grain
refinement. Substructure development was favored, whereas thermal twinning was reduced by
niobium. More generally, discontinuous recrystallization kinetics were considerably decreased.
Effect of Boron on Microstructure and Creep Deformation Behavior of Tempered Martensitic 9Cr Steel
Authors: Abe Fujio , Semba H. , Sakuraya T.
Published: March 2009

The effect of boron on microstructure and creep deformation behavior has been
investigated for a tempered martensitic 9Cr-3WVNb steel with emphasis on the role of boron free
from boron nitrides. Creep tests were carried out at 650oC for up to about 3 x 104 h, using
specimens of 10 mm in gauge diameter and 50 mm in gauge length. The addition of boron in
combination with no nitrogen addition effectively reduces the coarsening rate of M23C6 carbides by
an enrichment of boron in M23C6 particles in the vicinity of prior austenite grain boundaries during
creep at 650oC. This stabilizes martensitic microstructure during creep and retards the onset of
acceleration creep, resulting in a decrease in minimum creep rate and an increase in creep life.
Excess addition of boron and nitrogen causes the formation of boron nitrides during normalizing at
1050-1150oC, which reduces dissolved boron and nitrogen. The dissolved boron enriches in
M23C6 carbides, while the dissolved nitrogen causes the precipitation of fine MX carbonitrides.
The variation of creep rates in transient region and of the onset time of acceleration creep with
various combinations of boron and nitrogen contents can be explained by the dissolved boron and
nitrogen concentrations after normalizing into account.
Temperature Dependence of Lattice Distortion in Strongly Creep-Deformed Single Crystal Superalloy SC16
Authors: Schumacher G. , Darowski N. , Zizak I. , Klingelhöffer Hellmuth , Chen W. , Neumann Wolfgang
Published: March 2009

Specimens of single crystal superalloy SC16 have been pre-deformed at 1223 K to
strain of 15 % under tensile load of 150 MPa. The profiles of the 001 superlattice reflection of
the γ’ precipitate phase as well as the profiles of the 002 reflections of the fcc matrix phase
and of γ’-precipitate phase have been measured between RT and 1073 K by means of X-ray
diffraction (XRD). From these measurements the lattice distortion of the γ’ precipitates and
the lattice misfit between γ and γ’ phase have been determined as a function of temperature.
The width of the 001 reflection as well as the lattice misfit decreased as a function of
temperature. The results are ascribed to the anisotropic arrangement of dislocations at the γ/γ’
interfaces and to the different thermal expansion coefficients of the γ- and γ’-phase. A
comparison of lattice misfit with previous measurements on moderately strained specimens
suggests that the measured changes in lattice structure are predominantly created in stage I of
creep-deformation.
Drawbacks to the Application of Long-Term Degradation Tests, with Reference to Metal Dusting of Nickel-Base Alloys at High Temperatures
Authors: Stott F.Howard , Di Gabriele F. , Liu Zhu
Published: March 2009

Selection of alloys for components in industrial environments at high temperature is
often based on long-term tests in environments that simulate as closely as possible the actual
service conditions. However, particularly for alloys that rely on formation and retention of oxide
scales for protection, such tests may not be sufficient for this purpose. Several nickel-base alloys
have been exposed in an 80% CO-20% H2 gas mixture at 650oC for up to 5,000h, in order to give
conditions similar to those that can occur in petrochemical plant where high carbon and low
oxygen activities can lead to scale breakdown and the onset of metal dusting damage. The study
has shown that small changes in test conditions, such as the introduction of contaminants, the
addition of CO2, the proximity to alloy surfaces on which carbon deposition and metal dusting
have already been initiated and the proximity to other surfaces that can initiate such deposition,
can lead to very significant decreases in the induction period, prior to breakdown of the scale and
the onset of dusting.
Phase Transformation for Primary Particles in the Surface Regions of an AA1200 Alloy
Authors: Pettersen Tanja
Published: March 2009

In the present investigation the particle structure in an AA1200 sheet ingot used for litho
applications has been studied. Caustic etching of the as-cast material was seen to result in a zone
close to the surface with a different etching response. This zone was identified as what is known as
a fir-tree zone or an Altenpohl zone [1,2,3,4]. A variation in particle type over the cross section of
the as-cast ingot was seen to follow the differences in etching response. After heat treatment of the
material, the fir-tree zones were no longer visible, and the accompanying change in particle
structure was studied. Samples from the subsurface regions and from a distance of ~20 cm from the
surface has been investigated before and after heat treatment. In the as-cast material, the sample
from the surface was dominated by featherlike particles with long strings of particles, identified as
AlmFe. While closer to the centre Al3Fe and Al6Fe were seen to be the main phases, however, some
AlmFe and probably some α-AlFeSi was also found in this sample. After heat treatment, the particle
structure was seen to change, and the surface sample contained mainly Al3Fe in addition to a small
amount of AlmFe. The change in particle structure during heat treatment is discussed with reference
to the change in etching response.
TiNi Shape Memory Alloys for MEMS: Thin Film Deposition, Thermophysical Properties and Laser Micromachining Characteristics
Authors: Davies S.T.
Published: March 2009

The growth of TiNi thin films by ion beam sputter deposition using a Kaufmann type ion
source is described. Argon ions are used to sputter separate Ti and Ni targets to deposit nearequiatomic
TiNi thin films. Typically, ion energies and current densities of 1500 eV and 1 mA cm-2
respectively are used, with an argon overpressure of around 0.05 mtorr, to achieve deposition rates
of order 1 μm hr-1. The thermophysical properties of the deposited films were investigated by
thermal imaging. Patterning of TiNi films and foils with micrometre resolution using KrF excimer
laser ablation at 248 nm wavelength, with beam fluence up to 2.5 J cm-2, 15 ns pulse duration and
pulse rates up to 100 Hz has also been investigated.
The Effect of Crucible Configuration on Joule and Pinch Effects in EMCC Process of Silicon
Authors: Kim Bong-Hwan , Shin Je Sik , Lee Sang Mok , Moon B.M.
Published: March 2009

For the development of an economical production technology of multi-crystalline silicon,
an EMCC (Electro Magnetic Continuous Casting) process using a segmented Cu cold crucible was
practiced. In order to enhance significantly the heating efficiency of silicon melt keeping non-contact
condition during continuous melting and casting processes, the effects of Joule heating and
electromagnetic pressure in molten silicon were optimized by systematically varying crucible design
and configuration. Throughout the present investigation, multi-crystalline silicon ingot was
successfully produced at the casting speed of above 1.5 mm/min under a non-contact condition.