bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiscale Modelling of Stick-Slip Transition of Rough (Fractal) Surfaces
Authors: Chiaia Bernardino , Borri-Brunetto Mauro
Published: March 2009

The apparent shear strength of rock discontinuities is lower than that of small scale
samples. At the same time, the sliding behavior is characterized, in situ, by marked instabilities.
Numerical algorithms permit to calculate contact forces at any point, and to describe the stick-slip
transition. On the other hand, the critical aspects are not captured by classical theories. Multiscale
simulations show that the contact domain between rough surfaces is a lacunar set. This explains the
size-dependence of the apparent friction coefficient. By applying an increasing tangential force, the
regime of partial-slip comes into play. However, the continuous and smooth transition to fullsliding
predicted by the Cattaneo-Mindlin theory is not occurring in real situations. We implement a
numerical renormalization group technique, taking into account the redistribution of stress
consequent to partial-slip. This permits the critical value of the tangential force to be found. The
critical force is less than the one predicted by Coulomb’s theory, and depends on the specimen size
and on the topology of the interface.
Investigation on the Densification Mechanism of Warm Compaction
Authors: Xiao Zhi Yu , Ngai Tungwai Leo , Li Yuan Yuan
Published: March 2009

Warm compaction is a low cost process to make high density and high performance iron
base powder metallurgy parts. Based on results obtained from the dynamic compacting curve,
ejection force curve, X-ray diffraction, micro-hardness of iron powder, friction condition and
lubricant properties, densification mechanism of warm compaction can be drawn. In the initial stage,
the rearrangement of powder particles is the main factor. It contributes more in the densification of
warm compaction than that in cold compaction. However, in the later stage, the plastic deformation
of powder particles is the primary factor. The increase in plasticity at high temperature can
harmonize the secondary rearrangement of powder particles. During the compaction, the polymer
lubricant has great contribution to the densification of the powder, since it improves the lubricating
condition and effectively decreases the friction in the forming process and thus enhances the
compact density. The dynamic compacting curve of warm compaction can be divided into three
phases. The first is the particle rearrangement dominant phase; the percentage of particle
rearrangement in warm compaction is higher than that in cold compaction by 15-31%. The second
is the elastic deformation and plastic deformation dominant phase. The third is the plastic
deformation dominant phase. The study of the powder densification mechanism can direct
engineers in designing and producing warm compaction powders for high density parts.
A Study on the Development of Environment-Friendly Ag-SnO2 Electric Contact Materials through a Powder Metallurgy
Authors: Cho Hoon , Hwang Duck Young , Jo Hyung Ho
Published: March 2009

It is generally known that Ag-CdO electric contact material excels others in characteristics.
Thus, the contact material has been widely used, regardless of current strength. However, in a view
point of environment, the advanced electric contact material without environmental load element
such as cadmium has to be developed. Extensive studies have been carried out on Ag-SnO2 electric
contact material as a substitute of Ag-CdO contact materials. In the manufacturing process of
Ag-SnO2 electric contact material, it can be mentioned that typical internal oxidation process is not
suitable to produce Ag-SnO2 electric contact material because the Sn located around surface may
interrupt oxidation of Sn in the middle of material. Therefore, in the present study, powder metallurgy
including compaction and sintering is introduced to solve the incomplete oxidation problems in
manufacturing process of Ag-SnO2 electrical contact material. The formation of the blends was
manufactured by wet blending of powders of Ag and SnO2. The quantity of SnO2 powder was
15wt.%, with intent to optimize the powdering process for the minute powder of which diameter is
less than 5μ m. Particle size and grain distribution of Ag powder and SnO2 powder by powder
metallurgy were measured by image analyzer. In order to estimate the properties of specimen tested
with a variation of mixed time, the micro-hardness measurement was carried out. The Ag-SnO2-based
contact material, which was produced through this study, was actually set in an electric switchgear of
which working voltage is 462V and current is between 25 and 40A, for the purpose of testing its
performance. As the result, it excelled the existing Ag-CdO-based contact materials in
terminal-temperature ascent and main contact resistance.
An Effect of High Magnetic Field on Grain Growth in Nanocrystalline Iron
Authors: Tong W.P. , Wang L.M. , Ma G.J. , Tao N.R. , Zuo Liang
Published: March 2009

A nanostructured surface layer on a pure iron sample was prepared by surface
mechanical attrition treatment (SMAT). The thermal stability of SMAT sample was investigated at
different temperatures with or without a high magnetic field (H =12T). It was found that a high
magnetically annealing enhanced grain growth at the early stage of annealing, and produced a
uniform nanocrystalline grain structure. After homogeneous grains developed, further grain growth
became restrained.
Effect of Zr-Doped Ceria Catalyst on Carbon Deposition on Ni/YSZ Cermets
Authors: He Hong Peng , Hill Josephine M.
Published: March 2009

Carbon deposition on Ni/YSZ cermets and the role of Zr-doped ceria catalysts on carbon
deposition have been investigated in the present study. Upon exposure to methane, large amounts of
filamentous carbon formed on the surface of the cermets. In addition, carbon dissolved into the Ni
particles, significantly expanding the dimensions of the entire pellet. The addition of Zr-doped ceria
catalyst pellets on each side of the Ni/YSZ cermet significantly reduced the amount of deposited
carbon and affected the structure of the deposits. In particular, the carbon was more weakly bound
to the surface and appeared only to be deposited on the Ni/YSZ surface and not dissolved into the
structure.
Grain Size Saturation during Severe Plastic Deformation
Authors: Tsuji Nobuhiro , Kamikawa Naoya , Li Bo Long
Published: March 2009

Ultra-low carbon steel (ferritic steel), commercial purity aluminum and high purity copper
were heavily deformed by the accumulative roll bonding (ARB) process, and the microstructural
evolution during the ARB was analyzed. Significant grain refinement by grain subdivision
mechanism was confirmed in all three kinds of materials. On the other hand, microstructure
refinement slowed down with increasing strain and the grain size stayed in nearly a constant value in
the ultrahigh strain region. The mechanism of the grain size saturation was discussed.
Application of Local Tomography Technique to High-Resolution Synchrotron X-Ray Imaging
Authors: Ohgaki Tomomi , Toda Hiroyuki , Uesugi Kentaro , Kobayashi Toshiro , Makii Koichi , Takagi Toshiaki , Aruga Yasuhiro
Published: March 2009

X-ray CT method is a kind of nondestructive inspection, but has strong limitation in
sample size due to a small field of view (FOV). The higher the resolution, the smaller FOV is,
mainly due to the element number of available detectors commercially. Therefore, sample
machining is more or less necessary so that the sample size is fit within the small FOV in the case
of the high-resolution observation. Local tomography technique enables a high resolution
reconstruction of small region of interests within a sample without the sample machining. In this
study, we have evaluated the size effects of aluminum foam samples in terms of the 3D image
quality by the local tomography techniques.
Structure of Low Cobalt Alloy for Permanent Magnets of Basis System Fe-Cr-Co at Complex Two-Level Loading in Isothermal Conditions
Authors: Yusupov V.S. , Milyaev A.I. , Korznikova Galia F. , Korznikov Alexander V. , Kovneristii J.K.
Published: March 2009

Results of experimental research into evolution of the structure and microhardness of the hard
magnetic Fe-30Cr-8Co-0,7Ti-0,5V-0,7Si alloy during complex two-level loading (compression + torsion) in
isothermal conditions at various temperatures in single-phase region are reported. It was revealed that the
deformation leads to a strong refinement of initial coarse-grained structure in the whole volume of the
sample, however the generated structure is non-uniform through the body of the sample. In an active zone of
deformation, near to mobile head, there is a microcrystalline layer with a grain size of about 5 microns which
thickness poorly depends on the formation. With removal from the active zone of deformation the grain size
increases, and microhardness decreases.
Investigation, Application and Assessment of T122 Heat Resistant Steel
Authors: Liu Zheng Dong , Cheng Shi Chang , Bao H.S. , Yang Gang , Gan Yu
Published: March 2009

T122 is a competitive heat resistant steel used for the construction of ultra super
critical power stations. The authors experimentally investigated the effect of heat treatment and
variation of influential chemical elements, such as vanadium, copper and nitrogen, on the
microstructure and properties of the steel, in which the optimal heat treatment schedule during
heating was specified and the proper chemical element scope was also decided to achieve the
expected service performance. The application and potential of the steel in China today and
tomorrow were reasonably briefed. On the other hand, the authors also proposed some intrinsic
challenge of the steel, which may undermine the basis of the industrial application of the steel,
comparing to other candidates, i.e. T92 steel. An assessment on T122 steel was carefully made
from the viewpoint of industrial manufacturing and application.
Novel Concept of Austenitic Heat Resistant Steels Strengthened by Intermetallics
Authors: Takeyama Masao
Published: March 2009

Alloy design concept for the development of a new class of austenitic heat resistant
steels strengthened by Fe2M Laves phases (M: transition metals) has been proposed. The phase
diagram studies on Fe-Ni-M ternary systems demonstrate that Fe2Nb with C14 structure is the most
promising, because more than 40at% Ni can dissolve into the Fe sublattice sites and large γ+Fe2Nb
two-phase region exists along the equi-niobium concentration direction. The control of the c/a ratio
of the Laves phase using the composition homogeneity region by alloying makes it possible to
disperse the Laves phase finely in the γ matrix. Based on the knowledge, a model alloy Fe-20Cr-
30Ni-2Nb (at%) was proposed and the TTP diagram of the Laves phase was constructed. The Laves
phase homogeneously nucleates in the matrix and its fine morphology remains almost unchanged
even after long-term aging at 1073K.
Recent Activities on Directional Solidification at the State Key Laboratory of Solidification Processing
Authors: Liu Lin , Xie Fa Qin , Zhang Jun , Fu Heng Zhi
Published: March 2009

Directional solidification technique permits materials to grow along specific orientation, in order to obtain mechanical and/or physical anisotropy. The present research attempts to introduce the research work in the field of processing of some advanced materials by innovative directional solidification techniques performed at State Key Laboratory of Solidification Processing and with author’s intended research work. The paper deals with the specific topics on state of the art of directional solidification: single crystal superalloy and Nd-Fe-B alloys under high thermal gradient, Cu-Ni alloys under deep supercooling of the melt. The relevant solidification phenomena, such as morphological evolution, crystal growth for multi-phases in the processing of directional solidification, are discussed briefly. The trends of developments of directional solidification techniques are also prospected.
Computer Simulation on Formation of Precision Forgings of Titanium Alloy and Superalloy
Authors: Wu R.H. , Pang K.C.
Published: March 2009

The deformation features are analyzed for titanium alloy and superalloy during
isothermal/hot die forging process, and proper finite element models with appropriate parameter
values are determined. On the platform of DEFORM software, the formation processes of
vane-integrated disk and compressor disk, made of titanium alloy and superalloy respectively, are
simulated and analyzed. Based on the simulation results, some important suggestions to the process
design and parameter determination are brought forward, which have been taken into consideration or
adoption in practice. As a result, the production yield is promoted, and a large amount of expenses of
testing and die trial-manufacture are saved.
Mechanical Properties of Fe-Pd Ferromagnetic Shape Memory Alloy Thin Films Prepared by Dual Source DC Sputtering
Authors: Inoue Shozo , Namazu Takahiro , Fujimoto T. , Koterazawa Keiji , Inoue Kanryu
Published: March 2009

The purpose of this work is to quantitatively clarify the shape memory behavior of
Fe-Pd films containing ~30at%Pd by thermal cycling testing under various constant stresses.
Fe-Pd films (4 $m thick) were deposited onto Si wafers with thermally formed 1$m-thick SiO2
layer using a dual-source dc magnetron sputtering apparatus. The deposited films were all
annealed at 900°C for 60 min followed by iced water quenching. Perfect shape recovery was
observed for Fe-30.0at%Pd film when the applied stress was lower than 300 MPa. The maximum
recoverable strain was ~0.6%. Fe-29.2at%Pd film, on the other hand, showed unrecovered strain
after thermal cycling even if the applied stress was 40 MPa. XRD measurements of the
Fe-29.2at% Pd film before and after thermal cycling revealed irreversible fcc-bct martensitic
transformation that occurred during cooling process at a temperature around -80°C. The critical
stress of Fe-Pd films, at which plastic deformation commences to occur, is higher for films with 30
at% Pd than for films with 29.2 at% Pd, which is practically advantageous. The Ms temperature of
these films is lower than room temperature when no bias stress is applied, while it becomes higher
than room temperature when appropriate bias stress is applied, obeying Clapeyron-Clausius law.
Electrochemical Properties of Type 304 Stainless Steels Produced by Several Methods
Authors: Sunada Satoshi , Yamamoto Takahisa , Majima Kazuhiko
Published: March 2009

Three kinds of Type 304 stainless steels: the first one was made by the conventional wrought
process (I/M), the second one by conventional powder metallurgy process (P/M) and the third one
by Metal Injection Molding process (MIM), were used. The corrosion behavior of these specimens
was investigated through the potentiodynamic polarization curve measurement and electrochemical
impedance spectroscopy method. In addition, SCC characteristics were also studied. Both the
potentiodynamic polarization curve and the Nyquist plot curve of MIM specimen were similar to
those of I/M specimen, but different from those of P/M specimens. Therefore it might be suggested
that MIM process is quite suitable to improve the corrosion resistance. On the other hand, time
constants of P/M and MIM specimens are similar, but they differed remarkably from that of I/M
specimen, which is considered to be due to the remained pores in P/M and MIM specimens. Further,
it was also confirmed that the SCC was more liable to take place on I/M specimen than MIM
specimen.
Thermoelectric Properties of Arc-Melted Ba8Al16Si30 Clathrate
Authors: Lee Jung Il , Park Jong Bum , You Sin Wook , Lee Joo Ho , Kim Young Ho , Kim Il Ho , Jang Kyung Wook , Ur Soon Chul
Published: March 2009

Ba8Al16Si30 type I clathrate was produced by arc melting and thermoelectric properties
were investigated. The phase transformation behavior of arc-melted type I Ba8Al16Si30 was
examined by thermogravimetric analysis, differential scanning calorimetry, hardness test, density
measurement, X-ray diffraction and scanning electron microscope analyses. Homogenization was
carried out to induce the transformation to a thermoelectric phase at 773K to 973K for 5 hours and
24 hours in the vacuum furnace. Thermoelectric properties in the temperature range between 300K
and 600K were measured and evaluated. Electrical conductivity was decreased and Seebeck
coefficient was increased with increasing homogenization temperature and time. The arc-melted
and the homogenized specimens represented n-type conduction at temperatures examined, and they
showed reliable thermoelectric behaviors with increasing homogenization temperature and time.
Increase of Lankford Value of Al-Mg-Si Sheets for Automotive Panel Produced by Asymmetric Warm Rolling
Authors: Miki Yoshiki , Koyama Katsumi , Noguchi O. , Ueno Y. , Komatsubara Toshio
Published: March 2009

To restrain global warming, weight reduction of autobodies is needed for fuel saving and
discharge of carbon dioxide (CO2) gas. Usage of light weight aluminum alloy sheets is efficiency for
the weight reduction, but the less formabilities comparing with low carbon steel sheets restrict the
usage of autobodies applications actually. To improve the formabilities of aluminum alloy sheets,
asymmetric warm rolling is studied.
The formability of a metallic sheet strongly depends on the textures. Lankford value (r-value), one of
the indicators of formability, of recrystallized low carbon steel sheets is high because the density of
{111}//ND orientation suitable for deep drawing is high. The texture of conventionally cold rolled
and recrystallized aluminum alloy sheets mainly consists of cube texture which is lower r-value and
unsuitable for deep drawing. It is well known that similar texture to low carbon steel sheet can be
obtained by shear deformation in aluminum alloy sheets. To provide the shear texture in aluminum
alloy sheet, asymmetric warm rolling is carried out at 473K-573K with differential roll velocities. A
small amount of {111}//ND orientation which is hardly produced by conventionally cold rolling is
observed in asymmetric warm rolled aluminum alloy sheets after recrystallizing. Controlling the
asymmetric warm rolling conditions, such as rolling temperature, total reduction and asymmetric ratio,
higher r-value and deep drawability comparing with conventionally processed aluminum alloy sheets
are achieved. Other properties such as strength, elongation, and bendability of asymmetric warm
rolled sheets are almost same as those of conventionally processed sheets.
A Comparison of Grain Boundary Engineering Mechanisms in Copper and Brass
Authors: Randle Valerie , Owen Gregory
Published: March 2009

Grain boundary engineering (GBE) has been carried out on copper and brass. A
comparison of the resulting microstructure and grain boundary characteristics from the two
specimens revealed that the brass specimen had approximately the same number fraction of Σ3s as
the copper specimen (38%), but a lower number fraction of Σ9s and Σ27s and a markedly different
microstructure. In the brass specimen twins were not incorporated into the grain boundary network,
whereas in the copper specimen Σ3s replaced portions of the grain boundary network. These two
mechanisms are discussed in detail.
New Grain Interaction Models for Deformation Texture Simulations
Authors: Quey R. , Ringeval S. , Piot David , Driver Julian H.
Published: March 2009

Two relatively simple schemes are described for the interactions of grain deformations
during large plastic deformations with the aim of evaluating their influence on texture development.
The stress transfer model basically assumes that there is some degree of stress transfer across the
boundaries proportional to the boundary area. The reduced stress incompatibility model minimizes
the stress incompatibilities between each grain and their surrounding grains These models assume
3D topological schemes using evolving truncated octahedra for the spatial distributions of the
grains. They are applied to the cases of hot rolled and cross forged Al alloys. Both give quite similar
predictions for texture development which are moderate improvements on the Taylor models,
confirming that the incorporation of grain interaction effects can be useful for texture modeling
without major modifications. Moreover, they can yield interesting results for local orientation
effects and their influence on orientation stability; an example of cube grains hot rolled in different
crystallographic surroundings is also treated.
Deformation Conditions and Stability of the Basal Texture in Magnesium
Authors: Al-Samman Talal , Gottstein Günter
Published: March 2009

Texture evolution and microstructure development of hot extruded pure
magnesium and the magnesium alloy AZ31 deformed by plane strain deformation at select
temperatures and strain rates were investigated using X-ray techniques, electron back
scattered diffraction (EBSD) and optical microscopy. At a deformation temperature of 200 °C
both materials showed a heterogeneous microstructure consisting of highly deformed zones
appearing as huge grains or bands and of very small (~ 3 μm) grains. High temperature
deformation (400 °C) gave rise to completely different microstructures. Changing of
deformation conditions, i.e. the temperature and strain rate resulted in different final textures.
At high deformation temperature and low strain rate the formation of a basal texture was
suppressed.
Twinning and Detwinning during Cyclic Deformation of Mg Alloy AZ31B
Authors: Brown Donald W. , Jain A. , Agnew Sean R. , Clausen Bjørn
Published: March 2009

Textured Mg alloys exhibit tension – compression strength asymmetry due to mechanical
twinning. The distinction arises as the material deforms primarily by slip in one direction and by
twinning in the other. In-situ neutron diffraction during cyclic loading in tension and compression of
extruded bar allows study of the effect of twinning on subsequent load reversals. The diffraction data
reveal the texture evolution and internal stress development as a function of deformation.
De-twinning resulted in complete texture reversal during initial cycles, but eventually “fatigued”
resulting in some residual twin component.
Reversion Treatment to Improve Bake Hardening Response of a Twin-Roll Cast 6016 Automotive Sheet
Authors: Birol Yücel
Published: March 2009

Heat-treatable Al-Mg-Si aluminum alloys for automotive body panel applications are
shipped and formed in T4 temper while still formable and are subsequently given a bake cycle to
increase strength by age hardening while the paint is cured. However, the hardening response
during the rather short industrial paint-bake is impaired upon natural ageing after the solution
treatment. It is thus essential to counteract the adverse effect of natural ageing on bake hardening.
While this is often accomplished by an additional ageing cycle before the paint-bake treatment,
reversion treatments ought to be used once substantial natural ageing has first taken place to
improve the bake hardening response of a twin-roll cast 6016 sheet. The present work was
undertaken to improve the paint bake response of a twin-roll cast 6016 sheet by employing
reversion treatments before the paint-bake cycle. Reversion treatments between 200°C and 250°C
was effective in improving the bake hardening response of the twin-roll cast 6016 sheet which,
when processed without reversion, failed to meet in-service strength requirements with a rather poor
bake hardening response of 35 MPa.
Luminance Characterization of La3Ga5SiO14 Thin Films by Sputtering Deposition
Authors: Hu Yi , Wang Feng Wei , Lin Hur Lon
Published: March 2009

La3Ga5SiO14 (LGS) thin films were grown on (200)-textured MgO buffer layer, which
was deposited on the silicon wafer, by sputtering at 600°C. These thin films were annealed and
transformed form amorphous to the LGS crystalline phase with the heat treatment temperature
higher than 1150°C. It was found that the films with LGS crystalline phase showed luminescent
characterization whereas the LGS sintered solids did not. The emission peak of the films was
found to be 438 nm under the excited light of λex=300nm. Effects of annealed temperature on the
luminescent properties of the thin films are investigated. The relationship between the mechanism
of luminescence and the crystalline structure of the LGS films are discussed.
Atomic Assembly of Thin Film Materials
Authors: Zhou X.W. , Murdick D.A. , Gillespie B. , Quan J.J. , Wadley Haydn N.G. , Drautz Ralf , Pettifor David
Published: March 2009

The atomic-scale structures and properties of thin films are critically determined by the
various kinetic processes activated during their atomic assembly. Molecular dynamics simulations
of growth allow these kinetic processes to be realistically addressed at a timescale that is difficult to
reach using ab initio calculations. The newest approaches have begun to enable the growth
simulation to be applied for a wide range of materials. Embedded atom method potentials can be
successfully used to simulate the growth of closely packed metal multilayers. Modified charge
transfer ionic + embedded atom method potentials are transferable between metallic and ionic
materials and have been used to simulate the growth of metal oxides on metals. New analytical bond
order potentials are now enabling significantly improved molecular dynamics simulations of
semiconductor growth. Selected simulations are used to demonstrate the insights that can be gained
about growth processes at surfaces.
Molecular Dynamics Simulation on Formation of Icosahedron and Coalescence of Pt Nanoclusters
Authors: Lee Sung Hoon , Han Sang Soo , Kang Jeung Ku , Lee Hyuck Mo
Published: March 2009

The molecular dynamics (MD) simulation employing the embedded atom method
(EAM) has been performed to examine the phase stability of Pt nanoclusters, Ptn (n=38, 147, 309
and 561 atoms) with size and temperature. From heating and freezing curves of the nanoclusters,
the clusters (Pt147, Pt309 and Pt561) larger than 1 nm in size showed an icosahedral morphology near
460 ~ 660 K during freezing, where the formation energy of the icosahedral phase is 0.051 eV/atom
for Pt147, 0.056eV/atom for Pt309 and 0.067 eV/atom for Pt561. We also investigated coalescence
between two Pt nanoclusters and observed that the minimum size of the coalescent one is around 1
nm at 673 K.
Superplastic Properties of a Newly Developed Al-Mg-High Mn Aluminum Alloy Sheet
Authors: Ichitani Koji , Tagata Tsutomu
Published: March 2009

A new superplastic Al-Mg-high Mn alloy called a high-Mn alloy in the present paper was
developed. The superplastic properties of the high-Mn alloy were evaluated in comparison with a
conventional superplastic 5083 alloy which was manufactured under the same industrial mass
production process. The high-Mn alloy sheet of a middle thickness shows a lager elongation to failure
at temperatures below 783K, and show better superplastic formability and less cavitation volume than
the 5083 alloy. These superior characters of the high-Mn alloy may be ascribable to finer grain
structure formed in the alloy.
Melting and Casting of Titanium Alloys
Authors: Sung Si Young , Kim Young Jig
Published: March 2009

Over the past decades, a large number of researchers have been trying titanium alloys in an
attempt to combine most of their advantages, such as high specific yield strength, good corrosion
resistance, excellent fatigue property and biocompatibility by casting route. However, the wide use of
titanium alloys casting has been limited, since it is considered as only a near net shape forming
process in titanium alloys due to the catastrophic reactivity of molten states, the alpha-case
formations and the casting defects. In order to maximize the unique property of titanium alloys
casting which are comparable to wrought products and quite often superior, it is necessary to take a
close examination of titanium alloys casting procedure. Therefore, the merits and demerits of various
melting devices, pouring methods and mold materials will be addressed with regard to improving
titanium alloys casting.
Temperature and Strain Rate Effects on Plastic Deformation of Titanium Alloys
Authors: Ogawa K.
Published: March 2009

Since titanium alloys are the most promising structural materials for the high velocity
vehicles, the impact tensile strength of the materials is presently investigated. Three kinds of
aging treatments on the beta-titanium alloy were performed, and the tensile deformation behaviors
were identified in the wide range of the temperature and the strain rate. The stress－strain relations
of the titanium alloy significantly depend on the temperature and the strain rate investigated.
Thermally activated process concept was applied to explain the experimental results, and the
stress-strain relations at high strain rates were well understood with taking account of adiabatic
heating effect. It has been found that the stress-strain curves depend on the microstructures, while
the temperature and the strain rate effects are almost independent of the different aging treatments.
Micro Metal Injection Molding Process for High Performance Titanium Alloy
Authors: Miura Hideshi , Tanaka Shigeo , Osada Toshiko , Uemura Makoto
Published: March 2009

In this study, gas nitriding was processed for various sizes of Ti specimens which were
produced by metal injection molding (MIM) process, for the sake of enabling the high functionality at
low processing cost. It was shown by the nitriding treatment that the hardness of the surface increased
extremely and the microstructure changed to the TiN and acicular α-Ti phase. With respect to the
effect of the nitriding on the size of parts, micro dumbbell specimen had around five times higher
content of nitrogen than the block ones. It was suggested that the size of μ-MIM products is so small
that the surface treatment can contribute significantly to improve the properties, and then gas nitriding
process may be one of effective surface treatment methods for high functionality of μ-MIM Ti
products.
Damage Mechanisms of 5A06 Al Alloy Weld Joints under Constant Load and Thermal Cycling Condition
Authors: Jin Cheng , Niu Ji Tai , He Shi Yu , Geng Hong Bin , Long G.
Published: March 2009

In this paper, the micro-damage mechanisms of 5A06 Al alloy weld joints have been
studied under the condition of constant load and cyclic thermal load. The mechanical
performance variation of the base material and its weld joint are analyzed and
compared. Microstructure analysis reveals that the main damage mechanism in weld
joints is the interior voids nucleation and growth. The voids distribution and evolution
govern the damage process. Test results also show most fractures occur at HAZ near
the welding fusion line. The development of these voids results in the performance
deterioration of the weld joints under thermal cycling condition.
Local Manufacture of MMC Using FSW
Authors: Nishihara T. , Yamamura K.
Published: March 2009

Friction stir welding (FSW) has been generating interest in association with friction stir
processing (FSP), a new technique that employs FSW tooling. FSP is being investigated as a
thermo-mechanical processing tool to transform a heterogeneous microstructure into a more
homogenous microstructure.However, very little data is available on the use of FSW for processing
composite materials. In this study, a novel method of local manufacture of metal matrix composites
(MMCs) using FSW is proposed and its application to friction stir spot welding (FSSW) is described.
Trials investigating local manufacture of aluminum oxide particulate reinforced 6063 Al by friction
stirring were carried out on a modified milling machine. The results are discussed in terms of
weldability and residual microstructure.
Projection of Extrusion Force of Spray-Formed Al-25wt%Si with High Temperature Compression
Authors: Chiang C.H. , Tsao Chi
Published: March 2009

The extrusion forces of the spray-formed Al-25wt%Si alloy at various strain rates and
temperatures were calculated with the flow stresses obtained from high temperature compressive
tests. The compressive stress-strain curves of the spray-formed Al-25wt%Si at various
temperatures and strain rates were determined and discussed. The constitutive equation of strain
rate as a function of stress and temperature described by, n Q RT A e ' / sinh( ) − ε& = ασ for the
spray-formed Al-25wt%Si alloy, was established. The activation energy and constants in the
constitutive equation were discussed and compared to other Al alloys. A direct extrusion
experiment was employed to evaluate the extrusion loads vs. ram displacement at various
temperatures and strain rates. By applying the constitutive equation, the extrusion loads were
calculated and compared to the experimental ones for various temperatures and strain rates. The
accuracy of the calculated results compared to the experimental results was discussed.
Microstructure Evolution and Microstructure-Property Relationships in Friction Stir Processing of NiAl Bronze
Authors: McNelley Terry R. , Oh-ishi Keiichiro , Zhilyaev Alexandre P.
Published: March 2009

Friction stir processing (FSP) has been employed for localized modification and control of
microstructures in NiAl bronze materials, which are widely utilized for marine components. The
thermomechanical cycle of FSP results in homogenization and refinement and the conversion of
microstructures from a cast to a wrought condition within stir zones in the material. However, the
direct measurement of stir zone temperatures, strains, strain rates and cooling rates is difficult due to
steep gradients and transients in these quantities, and this is an impediment in the assessment of
FSP-induced microstructures and properties. Quantitative microstructure analyses following FSP of
cast NiAl bronze materials have been used to develop estimates of stir zone thermomechanical cycles.
The estimation procedures will be reviewed and the microstructure-based estimates will be compared
to results from computational models and embedded thermocouples measurements. Stir zone
microstructures comprise a mixture of primary α grains and transformation products of the β that
formed during processing. Recrystallization in the primary α occurred due to particle-stimulated
nucleation in this low stacking fault energy material. Factors that influence the distribution of strength
and ductility in the stir zone appear to include the mixture of microstructure constituents and gradients
in microstructure due to gradients in processing conditions.
Tensile and Fatigue Properties of Friction Stir Processed NiAl Bronze
Authors: Fuller Christian B. , Mahoney Murray W. , Bingel William H. , Calabrese Michael , London B.
Published: March 2009

Friction stir processing (FSP) produced local microstructural refinement in cast Ni
Al Bronze. The refined microstructure quality was evaluated with mechanical property
characterization using monotonic tension and fatigue testing as a function of FSP raster
patterns. Modifying the cast NiAl bronze with FSP resulted in a 140 - 172 % increase in
yield strength, and a 40 - 57% increase in tensile strength. Changing the raster pattern from a
linear to a rectangular spiral raster increased the tensile elongations by 40 - 134%. This
increase in elongation was attributed to increased microstructural uniformity through the
depth of the FSP raster. The ability to transfer FSP technology was demonstrated with
consistent tensile property data produced by three different laboratories. Fatigue
characterization (both uniaxial and rotating-bending fatigue) showed that FSP improved the
cast NiAl bronze fatigue resistance. Both types of fatigue testing showed differences in
fatigue resistance as a function of processing parameters.
Friction Stir Welding of Precipitation Hardened Ni Based Alloys
Authors: Jun Hyun J. , Ayer Raghavan , Neeraj Thirumalai , Steel Russell
Published: March 2009

Commercial Waspaloy plates with two different initial microstructures (annealed and
aged) were joined by Friction Stir Welding (FSW). This study presents the evolution of the grain
structure, and precipitation, dissolution and reprecipitation of the γ' phase during FSW using Optical
Microscopy, Scanning Electron Microscopy and Transmission Electron Microscopy. The
relationship between microstructure and microhardness is also discussed.
In Situ Observation of Weld Solidification and Phase Transformation Process Using Synchrotron Radiation
Authors: Komizo Yuichi , Terasaki Hidenori , Yonemura Mitsuharu , Osuki Takahiro
Published: March 2009

In order to understand the microstructure changes during welding processes , kinetic
information about the phase transformation is essential. In our research group, in-situ observation
systems consisting of undulator beam and imaging plate and two dimensional pixel detector have
recently been used. These make it possible that phase transformation can be identified in real-time
under the condition of directional-oriented solidification . In the present work, a combination of
analyzing method: the in-situ observation system by X-ray diffraction technique using intense
synchrotron radiation, and morphological observation by high-temperature laser scanning confocal
microscopy is suggested to analyze the phase transformation during the welding process. Using the
results acquired by these analysis methods, phase evolution of hypereutectoid carbon steel, during
fusion welding was analyzed. The primary phase was directly identified as an austenite phase.
Precipitation of pearlite phase was observed followed by the martensitic transformation.
Use of Synergistic Effects in High Power Laser-GMA Hybrid Welding for Manufacturing of Thick Walled Structural Pipes
Authors: Achar D.R.G. , Parhar S. , Dilthey U.
Published: March 2009

In the manufacturing thick structural pipes recently a new process has been developed. This
Paper describes this newly discovered process called Laser Hybrid welding. In laser hybrid welding
two processes i.e. laser welding and Gas Metal Arc (GMA) welding are combined together to create
synergistic effects.
In laser GMA hybrid welding of plates with thicknesses of up to 20 mm, the problem of pore
formation and of centre rib defects occurs frequently which have, up to now, not yet been subject to
detailed scientific analysis. It was the objective of this research work to reduce these weld defects
by weld parameter investigations (of a geometrical and also metallurgical nature) or to even avoid
them completely.
It was investigated to determine the extent to which shielding gas composition, (root) gap
width and misalignment of the joining partners affect the techno-mechanical properties. For this
purpose, the welds were subjected to non-destructive test methods (viz. visual inspections and X-ray
examinations) and also to destructive test methods (viz. transverse sections hardness measurements,
tensile tests and notch bending tests). The synergistic effects have been discussed in the light of the
mechanical and metallurgical characterisations of the weldments. Optimum process parameters have
been evolved which could tolerate up to 0.4mm root gap and 0.8mm of misalignment without
causing any centreline cracking. Combinations of helium and argon gas shielding have been found
to produce porous free welds.
It has been concluded that it is possible to replace submerged arc welds by laser GMA
hybrid welds in the manufacturing of longitudinally welded pipes.
Influence of Alloying Elements on Interfacial Reaction and Strength of Aluminum/Steel Dissimilar Joints for Light Weight Car Body
Authors: Hirose Akio , Imaeda Hirotaka , Kondo Miki , Kobayashi Kojiro F.
Published: March 2009

Dissimilar joining of Al alloys and steel was carried out using diffusion bonding process.
The effects of Si and Mg contents of Al alloys and bonding parameters on the interfacial reaction were
fundamentally investigated. While the reaction layers consisting of Fe-Al type intermetallic
compounds (IMCs) formed at the interfacial region, in the joint with Al alloys including 1mass% Si or
more a ternary Fe-Al-Si IMC layer formed at the Al alloy side. The growth of the reaction layers
followed the parabolic growth low. A maximum joint strength was obtained at an average reaction
layer thickness ranging from 0.5 to 1μm. The thicker reaction layer caused the fracture of the joints at
a lower stress because of brittleness of the IMCs, and the thinner reaction layer including un-bonded
interface also resulted in a low joint strength. As a result a thin and uniform reaction layer including
less un-bonded interface can realize a high joint strength. Since the Fe-Al-Si IMC layer uniformly
formed more rapidly than the binary Fe-Al IMCs in the joint with Al alloys including 1mass% Si or
more, a higher joint strength was obtained at a thinner average reaction layer. As a result, it was found
that the chemical compositions of 6000 series Al alloy controlled to be Mg (0.6 to 1.0mass%) and Si
(more than 1.0mass%) were appropriate to obtain the better bonding characteristics.
Crystallographic Texture of Dissimilar Laser Welded Al5083-Al6013 Sheets
Authors: Brokmeier Heinz Günter , Lenser Sabine , Schwarzer Robert A. , Ventzke Volker , Riekehr Stefan , Koçak Mustafa , Homeyer Jens
Published: March 2009

Dissimilar welded components joined with any kind of welding technologies gain
an increasing interest due to significant improvements in engineering structures by using new
materials (alloys) or new materials combinations. The present paper deals with laser welding
of Al5083-H111 and Al6013-T6 and the characterization of the crystallographic texture. Fine
grained Al5083 was joined with coarser grained Al6013.Whereas, Al6013 is strongly oriented
dominated by a strong cube component and a much lower Goss component, the finer grained
Al5083 shows a week deformation texture. The welding seam itself has a moderate cube
texture with a minor <100> fiber texture in welding direction. A small texture variation about
the texture strength and the volume fraction of the fiber component was observed along the
weld. Results were obtained by neutron, hard X-ray and electron diffraction.
Anodic Bonding of Ag-Impregnated Glass and Reaction of Derived Joints to Reverse Voltage
Authors: Takahashi Makoto , Ikeuchi Kenji
Published: March 2009

When a voltage in the direction opposite to that for anodic bonding is applied to an anodically-bonded joint of glass whose alkali ion content is substituted by silver, silver precipitates of peculiar morphology form in the glass adjacent to the joint interface. In order to acquire knowledge about factors that control the configuration of the precipitates, effects of bonding time of the joints and application temperature of the reverse voltage on morphology of the precipitates were investigated. Shortening of the bonding time and increase of the application temperature of the reverse voltage cause decrease of the size of precipitates, and these effects were explained from formation frequency of current paths in the Ag+ depletion layer with penetration of Ag+ ions into the layer.
Characteristics of Nd:YAG Laser Welded 600MPa Grade TRIP and DP Steels
Authors: Kang Chung Yun , Han Tae Kyo , Lee Bong Keun , Kim Jeong Kil
Published: March 2009

The characteristics of Nd:YAG laser welded 600MPa grade TRIP(transformation induced
plasticity) and DP(dual phase) steels with respect to hardness, microstructures, mechanical
properties and formability was investigated. A shielding gas was not used, and bead-on-plate
welding was performed using various welding speeds at a power of 3.5kW.
In the case of TRIP steel, the hardness was the highest at the fusion zone(FZ) and HAZ near the FZ
and decreased as the base metal was approached. The maximum hardness increased with increasing
welding speed to 3.6m/min and then remained. The microstructures of FZ and HAZ near the FZ
consisted of ferrite and bainite for all welding speeds.
In the case of DP steel, the maximum hardness was obtained at the HAZ near the FZ. It increased
rapidly to 2.1m/min and then showed nearly the same value. The difference between the maximum
hardness of HAZ and that of FZ increased with decreasing welding speed. The microstructure of FZ
was composed of acicular ferrite but the HAZ near the FZ contained bainite and ferrite at a low
welding speed.
Both steels had similar tensile properties and formabilities. In a perpendicular tensile test to the
weld line, all specimens were fractured at the base metal, and the strengths were somewhat higher
than those of raw metals. In a parallel tensile test, the strengths of the joints were higher than those
of raw materials but the elongations were lower. Formability was determined to be approximately
80% as compared with raw material at the optimum conditions.
Differences in hardness near the welded zone was dependant on the relative contents of ferrite.
Micro Flash Welding of Super Duplex Stainless Steels
Authors: Kuroda Toshio , Ikeuchi Kenji , Terajima Takeshi
Published: March 2009

Super duplex stainless steels were welded using new flash butt welding technology of
temperature controlling system. The super duplex stainless steel (329J4L) and conventional duplex
stainless steel (329J3L) were used. The samples were mounted in the dies using a Gleeble thermal
simulator and flash but welding was made. The specimens were heated up to 1373K for 10sec,
20sec and 30sec. Flash butt welding has consisting of a two stage processes of a flash action and a
contact resistance. First stage was a flash welding process and second stage was a solid state
bonding process. The cross sectional microstructure of the weld bond region showed two types of a
deposited fine particles region and a solid state bonding region. The grain growth was hardly
observed in the weld region and the heat-affected zone. For further increasing joining efficiency of
solid state bonding at the second stage, the welding time at 1373K was increased from 5 sec to
180sec. The bonding area increased with increasing welding time at 1373K and successfully welded
for conventional duplex stainless steel.
The Investigation of Diffusion Welding Process and Interfacial Microstructure and Properties on TiCN/Ni
Authors: Zhou Shi Quan , Zhao Hong , Dong Qiang
Published: March 2009

Affection of the main process parameters(Temperature and Time) on microstructure
and properties of Ti（C,N）/Ni interface has been studied by using Cu and Nb interlayer in Vacuum
diffusion welding device. Results have shown that interface interlayer did not change and interface
microstructure was Cu/Nb layer structure and Cu diffused into Ni with a little when diffusion
welding temperature was lower than 1273K. But when diffusion welding temperature was 1523K,
interface microstructures were Ni8Nb metallic compound and dispersing deposition CuNi solid
solution in the earlier, finally they were transformed into (Ti,Nb)(C,N)+Nb7(Ni,Ti,Cu)6+NbNi3 near
Ti（C,N） and NiCu+NbNi8 near Ni. It was clear that Cu was as transition liquid which dissolved Ni
so as to forming CuNi transition liquid, so that Nb was dissolved in CuNi transition liquid rapidly.
Ti(C,N) can been wetted with creating NiNbCu transition liquid, and then, a little (Ti,Nb)(C,N)
solid solution were formed at interface so as to increasing interface combining capability. Interface
shear strength may get to 140 MPa.