bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Twinning on Strain Rate Sensitivity during the Compression of Extruded Magnesium Alloy AZ31
Authors: Davies Chris H.J.
Published: March 2009

Samples of extruded magnesium alloy AZ31 (nominally 3 wt% Al, 1 wt% Zn, 0.3 wt% Mn,
with the balance magnesium) were tested in uniaxial compression at temperatures from room
temperature to 200°C. Monotonic and strain rate jump tests were conducted, and strain rate sensitivity,
and activation volume were determined. At the lower temperatures tested, strain rate sensitivity was
found to increase with strain to a limiting value, whereas at 200°C strain rate sensitivity initially
followed a similar trend, but did not reach a limit within the bounds of the test. The effect of
temperature on strain rate sensitivity was minor up to 150°C. Activation volume decreased with stress
by roughly an order of magnitude over the course of the tests. An analytical model was modified to
incorporate strain rate sensitivity, and it is shown that the evolution of material by twinning into an
orientation favourable for slip is principally responsible for the trend in strain rate sensitivity with
increasing strain.
Press Forging of Magnesium Alloy AZ31 Sheets
Authors: Zhang Shi Hong , Li Zhang Gang , Xu Yong Chao , Ren Li Mei , Wang Zhong Tang , Zhou Li Xin
Published: March 2009

Press forging of magnesium alloy AZ31 sheets was investigated in this paper. The typical
component, a rectangular box with bosses at the bottom was formed. The experimental results show
that the magnesium alloy sheets are suitable for press forging. The bosses and the rectangular box can
be formed synchronously for 2 mm or 3 mm thick sheets when the punch temperature is 250 °C. By
experimentation and numerical simulation, the effects of process parameters on material flow were
analyzed, including the temperature, the die shape, the blank size, the lubrication manners and the
friction condition.
Effects of Differential Speed Rolling on Microstructure and Mechanical Properties of AZ31 Magnesium Alloy
Authors: Huang Xin Sheng , Suzuki Kazutaka , Kwon Yong Jai , Watazu Akira , Shigematsu Ichinori , Saito Naobumi
Published: March 2009

A differential speed rolling (DSR) processing with a roll speed ratio of 1.167 was carried
out on an AZ31 alloy for investigating the effects of DSR on microstructure, texture and mechanical
properties. The DSR processed sheet showed unidirectional shear bands with a small grain size of
5.5 μm inclining to the rolling direction, and the basal plane tended to incline at about 15º from the
rolling plane toward the rolling direction. Compared with the normal rolled sheet, the DSR
processed sheets showed a lower proof stress and a larger elongation with an increase from 21% to
26% in the rolling direction. The proof stress increased and the elongation decreased with the
angle between the tensile direction and the rolling direction.
Microstructure and Texture Evolution during Large Strain Hot Rolling of AZ31 Mg Alloy
Authors: Lee Jae Seol , Son Hyeon Taek , Oh Ik Hyun , Cho Jae Ik , Kang Chang Seog , Bae Jung Chan
Published: March 2009

The aims of this study ares to investigate the microstructure evolution of AZ31 Mg alloys
with normal rolling and cross rolling during the large strain hot rolling affects microstructure,
texture and mechanical properties of AZ31 Mg alloy. In the microstructures of as-rolled both
samples, twins are clearly apparent, small and recrystallized grains are visible along some grain
boundary and twinned regions. The lankford values of large strain cross rolled sample obviously
demostrate the higher average r-value and lower planar anisotropy value. The press formaility of
large strain rolled Mg alloy might be improved due to control of texture and grain size by change of
the rolling direction.
Preparation and Characterisation of Open-Cell Microporous Nickel
Authors: Yamada Yasuo , Banno Takumi , Xie Zhen Kai , Li Yun Cang , Wen Cui E
Published: March 2009

In the present study, nickel foams with an open cell microporous structure were fabricated
by the so-called space-holding particle sintering method, which included the adding of a particulate
polymeric material (PMMA). The average pore size of the nickel foams approximated 10.5 μm; and
the porosity ranged from 70 % to 80 %. The porous characteristics of the nickel foams were observed
using scanning electron microscopy and the mechanical properties were evaluated using compressive
tests. For comparison, nickel foams with an open-cell macroporous structure (pore size
approximately 1.3 mm) were also presented. Results indicated that the nickel foams with a
microporous structure possess enhanced mechanical properties than those with a macroporous
structure.
Uniaxial Elasto-Plastic Behaviour of Adhesively Bonded Hollow Sphere Structures (HHS): Numerical Simulations and Experiments
Authors: Fiedler Thomas , Öchsner Andreas , Grácio José
Published: March 2009

This paper is on the investigation of adhesively bonded metallic hollow sphere
structures. Two different approaches, namely experimental analysis and finite element cal-
culations are applied and the findings of both attempts are compared. In the scope of the
numerical approach the influence of the mechanical properties of the adhesive on the me-
chanical response of the structure is analysed. Based on these results, suggestions for design
parameters are derived.
Thermal Stability and Nanocrystallization of Amorphous Ti-Ni Alloys Prepared by Cold Rolling and Post-Deformation Annealing
Authors: Brailovski Vladimir , Prokoshkin Sergey , Bastarash E. , Demers Vincent , Inaekyan K.E. , Khmelevskaya I.
Published: March 2009

The thermomechanical processing consisting in severe cold rolling (true strain 0.7–1.9)
followed by a post-deformation annealing (200-700oC) is applied to Ti-50.0 and 50.7at%Ni alloys.
The thermal stability of the amorphous phase as well as the influence of post-deformation annealing
on the structure, substructure and temperature range of martensitic transformations are studied using
TEM and DSC techniques. For a given level of cold work, the equiatomic alloy has a higher volume
fraction of amorphous phase than the nickel-rich one. For both alloys, the higher the volume fraction
of the amorphous phase, the higher the thermal stability. For a given post-deformation annealing
temperature, the DSC martensitic transformation peaks from the material subjected to amorphization
cold work are sharper and the hysteresis between the direct and reverse transformations is narrower
than those for a material subjected to strain hardening cold work. This observation confirms the
absence of the well-developed dislocation substructure in the severely deformed alloy subjected to
nanocrystallization heat treatment, which is consistent with TEM results.
X-Ray Study of Pd40Cu30Ni10P20 Bulk Metallic Glass Brazing Filler for Ti-6Al-7Nb Alloy
Authors: Miura E. , Ice Gene E. , Specht E.D. , Pang J.W.L. , Kato Hidemi , Hisatsune K. , Inoue I.
Published: March 2009

Crystalline precipitates in a bulk-metallic-glass (BMG) braze were investigated with an
intense x-ray microbeam. The precipitates were found in the Pd40Cu30P20Ni10 BMG braze matrix
after joining crystalline Ti-6Al-7Nb. However, the role (if any) played by the precipitates in
improving the mechanical bond of the BMG/crystalline joint is unknown. X-ray microdiffraction
and microfluorescence measurements from small sample volumes were made with an ~ 0.5 x 0.5
μm2 beam. Spatially-resolved Laue diffraction and x-ray fluorescence measurements were made
on several second-phase crystals within the BMG matrix. Although precipitate crystals with the
observed compositions were anticipated to be predominantly hexagonal, one of the crystals was
found to be cubic or tetragonal. The instrumentation includes capabilities for 3D depth-resolved
measurements of crystal structure and for fluorescence analysis of elemental composition. Depth
profiling gave information about the grain distribution and morphology in the BMG matrix.
On the Size of Representative Volume Element in Elastic, Plastic, Thermoelastic and Permeable Random Microstructures
Authors: Ostoja-Starzewski Martinos , Du X. , Khisaeva Z.F. , Li W.
Published: March 2009

The Representative Volume Element (so-called RVE) is the corner stone of continuum mechanics.
In this paper we examine the scaling to RVE in linear elasticity, finite elasticity, elasto-plasticity,
thermoelasticity, and permeability of random composite materials.
Plasticity in Bulk Metallic Glass Composites Containing Dual Amorphous Phases
Authors: Lee J.K. , Kim H.J. , Kim Take-Soo , Bae Jung Chan
Published: March 2009

Bulk metallic glass (BMG) composites with dual amorphous phases were fabricated by
spark plasma sintering of a mixture of Cu-based and Zr-based amorphous powders in their
overlapped supercooled liquid region. The Zr-based amorphous phases are well distributed
homogeneously in the Cu-based metallic glass matrix after consolidation. The BMG composite still
remains as an amorphous structure after consolidation. The BMG composite with dual amorphous
phases shows macroscopic plasticity after yielding, and the plastic strain increased to around 3.4%
in the BMG composite containing 30 vol% Zr-based amorphous phase. The successful
consolidation of BMG composite with enhanced plasticity was achieved by introducing a second
amorphous phase in the metallic glass matrix.
Electronic Structure and Phase Stability of Glassy Alloys
Authors: Hasegawa Masashi , Takeuchi Tsunehiro , Soda Kazuo , Sato Hirokazu , Mizutani Uichiro
Published: March 2009

The electronic structure and phase stability of the Zr-Ni-Al ternary glassy alloys, have
been systematically investigated experimentally and theoretically. Thermal stability and
crystallization process have been clarified by the DSC and XRD measurements. Composition
dependence of the stability parameter; Tg/Tl has been clarified. The electronic structure around the
Fermi level has been investigated by using the high resolution UPS. It is found that there is a
sizable pseudogap at the Fermi level of the electronic structure of the Zr65Ni20Al15 glassy alloy.
The DVXα calculations for the charateristic clusters in the Zr-Ni-Al glassy alloy having high glass
forming ability have been also performed. It is found that these clusters formation reduces the
internal energy and can contribute to the phase stability. The LMTO-ASA band calculations for
the Zr6NiAl2 compound which is the most relevant compound to the Zr60Ni25Al15 glassy alloy have
been also performed. It is found that there is a sizable pseudogap at the Fermi level in its
electronic structure, suggesting exiting of the pseudogap of the glassy alloy.
Viscosity Measurements of Zr55Cu30Al10Ni5 Supercooled Liquid Alloy under High-Speed Heating Conditions
Authors: Yamasaki Tohru , Maeda S. , Okai Daisuke , Fukami Takeshi , Yokoyama Yoshihiko , Nishiyama Nobuyuki , Kimura Hisamichi , Inoue Akihisa
Published: March 2009

Viscosity of a Zr55Cu30Al10Ni5 supercooled liquid alloy having bulk metallic glass
forming ability has been measured by using a penetration viscometer with a cylindrical probe
under high speed heating conditions at rates between 20°C/min and 400°C/min in the temperature
range from the glass transition temperatures (Tg) up to above the crystallization temperatures
(Tx). The viscosity of the alloy decreased with increasing the heating rate and tended to saturate at
the heating rate of 200°C/min and above. Corresponding measurements of the differential thermal
calorimetry (DSC) under the high-speed heating conditions have been also done.
Stress Corrosion Cracking Failure of Jackbolts for Die Casting Press
Authors: Manohar P.A.
Published: March 2009

Several prematurely failed jack bolts were analyzed to determine the root causes of
failure. Bolts were employed to ensure that die halves do not separate during casting of high
pressure die castings of light metals. Fractography of jack bolts revealed unusual morphology
consisting of both circumferential and longitudinal cracking. The basic fracture type was identified
as transgranular cleavage (brittle) fracture mode. SEM / EDS analysis of the fracture surface
revealed the presence of, to varying degrees, chemical species containing sulfur (S), oxygen (O)
and chlorine (Cl). Material composition, heat treatment, microstructure and hardnesses of the jack
bolts were found to be in agreement with the expected steel grade and properties. It was concluded
that the failure of the bolts was due to a combination of inappropriately chosen mechanical
properties of the bolts, operating stress, and the presence of corrosive environmental materials
leading to ideal conditions that promoted stress corrosion cracking failures. Suitable remedial
actions to alleviate the risk of SCC failure of the bolts are presented and discussed in the paper.
Ductile Crack Propagation Characteristics in Steel Thin Single Edge Notched Tension Specimens
Authors: Kayamori Yoichi , Hillmansen S. , Crofton P.S.J. , Smith Roderick A.
Published: March 2009

Static and dynamic ductile crack propagation tests were carried out using thin single edge
notched tension (SENT) specimens of carbon-manganese steel, each of which had a fatigue pre-crack
or a sharp V-notch as a crack initiator. The crack tip opening angle (CTOA) was measured using
digital images on the surface of the SENT specimens, and the critical values of CTOA for crack
propagation decreased with increasing crack length while initial crack growth was still small. After
the initial crack growth up to the distance of the specimen thickness, the critical CTOA remained
almost constant. These tendencies were common in static and dynamic crack propagation specimens
as well as fatigue pre-cracked and sharp V-notched specimens. There was no particular difference in
the static crack propagation characteristics of both fatigue pre-cracked and sharp V-notched
specimens. On average, it was observed that higher crack speeds affected the constant values of the
critical CTOA by slightly reducing them. The constant CTOA tends to decrease with an increasing
global constraint factor, and this suggests that the factor is insensitive to a crack starter, fatigue
pre-crack or a sharp V-notch, but relatively sensitive to crack speed.
Prediction of Ductile Crack Growth from Ductility of Steel
Authors: Ohata Mitsuru , Fukahori Takuya , Minami Fumiyoshi
Published: March 2009

This study pays attention to reveal the material properties that control resistance curve for
ductile crack growth (CTOD-R curve) on the basis of the mechanism for ductile crack growth, so
that the R-curve could be numerically predicted only from those properties.
The crack growth tests using 3-point bend specimens with fatigue pre-crack were conducted for
two steels that have different ductile crack growth resistance with almost the same CTOD level for
crack initiation, whereas both steels have the same “Mechanical properties” in terms of strength and
work hardenability. The observation of crack growth behaviors provided that different mechanisms
between ductile crack initiations from fatigue pre-crack and subsequent growth process could be
applied. It was found that two “Mechanical properties” associated with ductile damage of steel
could mainly influence CTOD-R curve; one is a resistance of ductile crack initiation estimated with
critical local strain for ductile cracking from the surface of notched specimen, and the other one is a
dependence of stress triaxiality on ductility obtained with circumferentially notched round-bar
specimens.
The damage model for numerically simulating the R-curve was proposed taking the two “ductile
properties” into account, where ductile crack initiation from crack-tip was in accordance with
critical local strain based criterion, and subsequent crack growth GTN
(Gurson-Tvergaard-Needleman) based triaxiality dependent damage criterion. The proposed
model accurately predicted the measured R-curve for the two steels used with the same “strength
properties” through ductile crack initiation to growth.
Microstructure and Mechanical Properties of Commercial Purity Copper Resulting from Repeated Groove Pressing Followed by Cold Rolling
Authors: Krishnaiah A. , Uday Chakkingal , Venugopal P.
Published: March 2009

Groove pressing (GP) is a severe plastic deformation technique for
producing ultra fine grain sized microstructures in metals and alloys. In the present
study, groove pressing and a two-step process of groove pressing followed by cold
rolling was used to investigate the potential of these processes to produce ultra fine
grained copper with significantly enhanced strength. Mechanical and microstructure
properties were evaluated after groove pressing and after groove pressing followed by
cold rolling. The advantages conferred by groove pressing prior to cold rolling on
producing copper with enhanced properties has been investigated.
Evaluation of Mechanical and Fracture Characteristics Using Instrumented Indentation Technique
Authors: Lee Jung Suk , Kim Kwang Ho , Han Jae Hwan , Kwon Dong Il
Published: March 2009

The material characterization on the weak points of the structural systems is essential to
evaluate safety accurately. However, general material characterization methods such as uniaxial
tensile test and CTOD (crack tip opening displacement) test are destructive, therefore, it cannot be
applied to the system in use. To overcome this problem, the material characterization using
instrumented indentation technique was developed. However, current researches on instrumented
indentation technique focus on the hardness measurement. The evaluation of flow property, residual
stress and fracture toughness using instrumented indentation technique is not sufficiently performed.
In this paper, we introduce the evaluation method of the flow property, the residual stress near the
weldment and the fracture toughness developed from damage mechanics. The algorithm of flow
property evaluation, the residual stress evaluation model and the fracture toughness model by using
indentation were verified comparing with the experimental results.
Ecomaterials-Foam Plastics Synthesized from Plant Oil-Based Resins
Authors: Rong Min Zhi , Zhang Ming Qiu , Wu Su Ping , Wang Hong Juan , Czigány Tibor
Published: March 2009

In this work, plastic foams were prepared from plant oil resins based on soybean oil and
castor oil. Firstly, epoxidized soybean oil (ESO) reacted with acrylic acid using N, N-dimethyl benzyl
amine as the catalyst, and castor oil was modified with maleic anhydride, respectively. Acid number
was used to monitor the reaction process, and structures of the resultant acrylated epoxidized soybean
oil (AESO) and maleate castor oil (MACO) were proved by Fourier Transform Infrared (FTIR)
measurements. It was found that the catalyst is quite effective in synthesizing AESO. Then, plastic
foams based on AESO and MACO were synthesized through free radical initiated copolymerization
with diluent monomers including styrene and methyl methacrylate. Mechanical properties,
reinforcing effect of sisal fiber and biodegradable feature of the foams were characterized, showing
the suitability of the bio-foams for acting as packaging materials.
Theoretical Study of Glass Transition Based on Cluster Variation Method
Authors: Mohri Tetsuo , Kobayashi Yoshitaka
Published: March 2009

Modeling of Glass transition is attempted based on the Cluster Variation Method. Free
energy functional of an L10 ordered phase is employed to describe the first order nature of the
transition. Free energy contour surface calculated as a function of temperature and an order
parameter which simulates an amount of defects provides a generalized stability diagram in which
the ideal glass transition temperature is identified as a critical point. Transition kinetics is
investigated by Path Probability Method which is the kinetics version of the CVM to time domain.
Continuous cooling behavior is calculated by explicitly incorporating the temperature dependent
viscosity term based on VFT (Vogel-Fulcher-Tamman) formula. The glass transition is realized as
the freezing of the order parameter due to the enhanced viscosity. The extension of the present
theoretical scheme to non-Bravais lattice is attempted by Continuous Cluster Variation Method.
Computer Simulation of Grain Growth in Three Dimensions by the Phase Field Model with Anisotropic Grain-Boundary Mobilities
Authors: Suwa Yoshihiro , Saito Yoshiyuki , Onodera Hidehiro
Published: March 2009

The kinetics and topology of grain growth in three dimensions were simulated using a
phase-field model with anisotropic grain-boundary mobilities. In order to perform large scale
calculations we applied both modifications of algorithms and parallel coding techniques to the Fan
and Chen's phase-field algorithm. Kinetics of abnormal grain growth is presented. It is observed that
the grains of a minor component which are at the beginning surrounded preferentially by boundaries
of high mobility grow faster than the grains of a major component until the texture reverses
completely. Additionally, topological results of grain structures, such as grain size distributions and
grain face distributions, are discussed
Modelling of Dynamic Recrystallisation of 316L Stainless Steel Using a Systems Approach
Authors: Abbod Maysam F. , Mahfouf M. , Linkens D.A. , Sellars C.M.
Published: March 2009

Dynamic recrystallisation (DRX) is an important aspect for industrial applications in hot
metal working. Although DRX has been known for more than thirty years, its mechanisms have never
been precisely investigated, in part because it was not readily possible to make local texture
measurements. In the present work, the material behaviour during DRX is investigated and modelled
based on the microstructure of 316L stainless steel. The developed model is based on a constitutive
equation Modelling technique which incorporates the strain, strain rate and instantaneous temperature
for predicting the flow stress of material being deformed under hot conditions.
Modelling of Oxide Scale Evolution in Hot Rolling and Descaling
Authors: Krzyzanowsky Michal , Beynon John H. , Frolish Mike F. , Clowe Samantha
Published: March 2009

Oxide scale behaviour in thermomechanical processing has been the subject of intensive
research for several years that allowed developing a finite element (FE) based model to simulate a
range of events of relevance to the process and the surface quality of the hot rolled product. A range
of experimental techniques have also been developed, each providing a partial insight. An overview
of this research is presented in the sequence of rolling and finishing with descaling. The model has
been extended to provide the basis for detailed numerical investigations of the roll/stock interface
behaviour during multi-pass hot rolling operations. The modelling techniques have been used for
providing design criteria for AISI430 ferritic stainless steel scale failure during bending. Modelling
of near surface deformation during rolling of aluminium alloys is under consideration.
Finite-Element Modeling of Multi-Pass Forging of Nickel-Base Alloys Using a Multi-Mesh Method
Authors: Barton G. , Li X. , Hirt Gerhard
Published: March 2009

Nickel-base alloys are mostly used for high-temperature applications, many of which are
heavily loaded safety components. The material properties highly depend on the microstructure,
which, in turn, depends on the metal forming process and the heat treatment. FEM integrated
microstructure models can satisfactorily describe the grain size development due to dynamic and
static recrystallisation during a metal forming processes and the heat treatment. The simulation
results obtained from modeled compression experiments are very promising so that consequently,
simulations of more sophisticated processes, like multi-pass open die forging or radial forging, is
the next reasonable goal. However, the computation times for the simulation of these processes are
still unsatisfactorily long and thus, their application is deterred. To accelerate the simulations, a
multi-mesh algorithm was implemented to the Finite-Element simulation package PEP &
LARSTRAN/SHAPE. This method uses a Finite-Element mesh that is fine in the deformation zone
and coarse in the remaining areas of the workpiece. Due to the movement of the tools during the
simulation, the deformation zone moves across the workpiece and thus, necessitates a remeshing
with a transition of the finely meshed area. A second mesh, which is fine over the entire volume of
the workpiece, is used to store the nodal data and simulation results, which get transferred to the
simulation mesh every time a remeshing operation becomes necessary. In combination with an
adopted data transfer algorithm, this second mesh is used to minimize the loss of accuracy, if a
previously finely meshed area becomes a coarsely meshed area. This simulation model can be used
to optimize forging process chains with respect to grain size distribution as well as cost
effectiveness and energy consumption.
Measuring and Modeling Grain, Grain Boundary and Grain Edge Average Curvature and their Application to Grain Growth
Authors: Rios Paulo Rangel , Fonseca G.S.
Published: March 2009

Alongside volume fraction, VV, and area per unit of volume, SV, the integral interface
curvature per unit of volume, MV, or the average interface curvature, H, are important
microstructural descriptors. For grain growth, the grain boundary curvature is of special importance
because, in addition to its geometrical significance, it is also the driving force for boundary
migration. Notwithstanding its importance, curvature has been seldom measured and utilized in the
analysis of polycrystals. Geometrical models were derived for the average curvature of individual
grains, of grain boundaries and of grain edges, as a function of the mean intercept length. These
models show good agreement with curvature measurements in an Al-1mass%Mn alloy.
Furthermore, this work shows how grain boundary curvature measurement can be applied to normal
grain growth as well as to the effect of particles on grain boundary pinning.
A Multi-Scale Model of Martensitic Transformation Induced Plasticity at Finite Strains
Authors: Kouznetsova V.G. , Geers M.G.D.
Published: March 2009

A physically-based multi-scale model for martensitic transformation induced plasticity is
presented. At the fine scale, a model for one transforming martensitic variant is established based on
the concept of a lamellae composed of a martensitic plate and an austenitic layer. Next, the behaviour
of 24 potentially transforming variants is homogenized towards the behaviour of an austenitic grain.
As a simple example, the model is applied to deformation and transformation of a single austenitic
grain under different deformation modes.
Multiscale Modelling of the Mechanical Behaviour of Oriented Semicrystalline Polymers
Authors: van Dommelen J.A.W. , Brekelmans W.A.M. , Govaert L.E.
Published: March 2009

For semicrystalline materials, a stacked lamellar morphology gives rise to a strongly
anisotropic mechanical response. A multiscale numerical model is used to simulate the effect of a
stacked lamellar microstructure on the macroscopic behaviour. The constitutive properties of the
material are identified separately for the crystallographic and amorphous domains. The averaged
fields of aggregates of individual phases, having different preferential orientations are determined.
The anisotropy of preferentially oriented material is investigated in different deformation modes.
Nonlocal Interface Mechanical Model
Authors: Borino Guido , Failla Boris , Parrinello Francesco
Published: March 2009

The paper presents a nonlocal elastic damage-frictional interface model. The reason to
introduce nonlocal mechanical features inside the constitutive relations is justified by the fact that
there are several circumstances, in which the interface displays inside an extended process zone with
microstructural spatial interactions. Typically, spatial bridging mechanical effects can be effectively
modeled by integral (strongly nonlocal) stress-strain relations. The paper develops an elastic nonlocal
model with local isotropic damage and the relations are constructed following a thermodynamical
consistent approach.
Consolidation and Mechanical Properties of Gas Atomized Al-Si Powder
Authors: Kim Yong Jin , Kim Jin Chun , Ahn Jung Ho
Published: March 2009

Hypereutectic prealloyed Al-20wt.%Si powders were prepared by the gas
atomization process. Characteristics of the atomized Al-Si powders were investigated. With
increasing gas pressure of the atomization, the average powder size and oxygen content
decreased. Primary Si particles in the as-atomized powders were about 8-10 ㎛. Sintering
behavior of the atomized Al-Si powders was discussed with sintering temperature.
As-atomized powders were hot-pressed and extruded into a cylindrical shape. 96-99% of
theoretical density was achieved by the hot consolidation. Microstructure changes as well as
hardness and tensile properties of the samples were evaluated in this paper.
Solute and Second Phase Evolution during Industrial Processing of AA3103
Authors: Miroux A. , Lok Zacharias J. , Marthinsen Knut , van der Zwaag Sybrand
Published: March 2009

The complete evolution of solute content and second phases during full-scale industrial
processing of AA3103 sheets has been measured. During pre-heating, dispersoids, which appear as
plates or small polyhedra grow and the Mn solute content decreases. During subsequent breakdown
rolling the dispersoid number-density increases significantly. The measured decrease of
solute Mn after hot rolling and coil cooling is attributed to constituent particle growth, whereas the
solute depletion during the final back-annealing is mainly caused by the growth of the dispersoids.
These observations are compared to the predictions obtained by a semi-physical model for
precipitation. Although simulations have been performed without any retro-fitting, for hot rolling
the results compare quantitatively well with experiment, while for coil cooling and back annealing
the modelled Mn solute depletion is underestimated. The precipitation process is found to be very
sensitive to the microstructure, which illustrates the importance of coupling precipitation models
with work hardening and softening models to obtain reliable predictions.
Application of Equal-Channel Angular Pressing to Aluminum and Copper Single Crystals
Authors: Furukawa Minoru , Horita Z. , Langdon Terence G.
Published: March 2009

This paper describes experiments in which high purity aluminum (Al) and copper (Cu)
single crystals of different crystallographic orientations were processed for one pass by
equal-channel angular pressing (ECAP). The deformed structures were examined using optical
microscopy (OM), orientation imaging microscopy (OIM) and transmission electron microscopy
(TEM). The results for Al single crystals are compared with those for Cu single crystals.
Effect of Non-Metallic Inclusions on Notched Low Cycle Fatigue in P/M IN100 Nickel-Base Superalloy
Authors: Wusatowska-Sarnek Agnieszka M. , Bhowal P. , Gynther Daniel , Montero Rick
Published: March 2009

The notched low cycle fatigue (LCF) behavior of a P/M (Powder Metallurgy) gas turbine disk superalloy (IN100) was investigated to determine the role of inclusions, such as oxides, that are intrinsic in the process of making powder superalloys. Tests were carried out at temperatures ranging from 426°C to 621°C at several applied stresses. The majority of LCF failures initiated from inclusions (oxides) with minority initiation sites being grain facet in the microstructure. The locations of initiation sites were surface or subsurface, and reduced LCF life was generally associated with surface initiation at the notch root. However, surface initiation was infrequent and observed only at high stresses (i.e., in the presence of large plasticity at the notch root). The stress gradient at the notch root coupled with inclusion size determined the critical conditions for fatigue initiation. In the present paper, these failures and the associated LCF life are discussed in terms of inclusion size and its proximity to the notch root.
The Effect of Chemistry and Cooling Rate on the Latent Heat Released during the Solidification of the 3XX Series of Aluminum Alloys
Authors: Djurdjevic Mile B. , Sokolowski Jerry , Kierkus Witold T. , Byczynski Glenn E.
Published: March 2009

The latent heat of solidification of any alloy depends on its chemistry that consequently affects the
macro and microstructures for the given solidification conditions. In order to analyze the effects of
chemistry on the release of latent heat during solidification of the industrial 3XX series of aluminum
alloys, four different levels of silicon (5, 7, 9 and 11wt% Si) and three different levels of copper (1, 2
and 4 wt% of Cu) were taken into consideration. The solidification process was studied at cooling
rates of 6 and 10°C/minute. The solidification path of these alloys was determined and the
corresponding latent heat released during the solidification process was measured using a
Differential Scanning Calorimeter (DSC). The tested hypoeutectic alloy chemical composition was
expressed by the novel concept of silicon equivalency. The findings indicate that increases in the
cooling rates shift the characteristic temperatures toward lower values without having a significant
effect on the amount of released latent heat.
Change in Morphology of γ' of Prior-Crept Single Crystal Nickel-Based Superalloy, CMSX-4, with Simple Aging
Authors: Miura N. , Kurita K. , Kondo Y. , Matsuo Takashi
Published: March 2009

It has been elucidated that the small creep strain must be essential to form the rafted γ/γ'
structure using a single crystal nickel-based superalloy, CMSX-4. To confirm the amount of the
strain required to make rafting, the single crystals interrupted the creep tests up to a strain of 0.01 at
1273K-250MPa was aged at 1273K without stress. To compare the difference in the morphology of
the γ/γ' structure of the as-heat treated and the creep-interrupted single crystal with the simple aging,
the as-heat treated single crystal was also aged. Microstructural observations by SEM were
conducted for the specimens sectioned parallel to (100). The cuboidal γ' precipitates of the as-heat
treated single crystal connected each other with three <100> directions after the simple aging. By
employing the aging without stress on the specimen interrupted the creep test at a strain of 0.0074,
the drastic morphological change in the γ/γ' structure was confirmed, that is, the γ/γ' structure
changed to rafted one perpendicular to the creep-interrupted stress axis. The aspect ratios of the
creep-interrupted specimens increased with increasing simple aging time, and attained to the
maximum value at the simple aging time of 3.60x106s. The maximum value of the aspect ratios
increase with increasing creep-interrupted strain and attained 4 at a strain of 0.0074. The dislocation
density at the γ/γ' interface increases with increasing creep strain. Consequently, the formation of
the rafted γ/γ' structure requires the dislocation substructure induced by the creep strain.
Role of Transient Creep in γ-Single Phase Ni-20Mass%Cr Alloy
Authors: Matsuo Takashi
Published: March 2009

Through the analysis of many creep rate-strain curves of γ-single phase Ni-20mass%Cr
alloy single crystals with various stress axes, it has been elucidated that the ratio of transient stage
to rupture life becomes larger with decreasing the stress. And the transient stage consists of Stage
I and Stage II. In Stage I, the creep rate just after loading remains constant, and in Stage II, a steep
decrease in creep rate continues. It is noticeable that there is a marked difference in transient stage
among single crystals with different stress axes. The aim of this study is to elucidate the
mechanisms leading to the different transient stages as the function of stress axes. The
deformation during transient stage in the single crystals except for the single crystals with the stress
axes of the [001] and [1,–11] poles in the standard stereographic triangle, proceeds using the
primary slip plane. And they are divided into two groups of the single crystals with the angle
between stress axis and primary slip plane, θ, less than 45° and the single crystals with θ more than
45°. The deformations of Stage I and Stage II in these single crystals proceed using the slip
system of (111)<1,–01> and the slip system of (111)<1,–10>, and in Stage I, the former slip system
acts mainly except for that of single crystals with stress axis of [011]. While, in the single crystal
with stress axis of [011], two slip systems above described operate at the beginning of Stage I, and
the stress axis moves along [011]-[1,–11] line. And this moving gives slight increase in the
Schmid factor, therefore, in Stage I slight increase in creep rate was confirmed. The {111} pole
figure of the single crystal with stress axis of [1,–11] whose deformation proceeds using the plural
slip planes are obtained by SEM-EBSD method. It becomes clear that the smallest strains of Stage
I and Stage II derived from the increase in the torsion with creep deformation.
Behavior of Hydrogen in Al-4%Mg Alloys during Heat Treatment
Authors: Umeda Hidetoshi , Itoh Goroh , Kato Yoshinori
Published: March 2009

The effect of the annealing atmosphere, the annealing temperature etc. on the hydrogen
behavior in several Al-4% Mg alloys during heat treatment, was investigated. The results have shown
that the hydrogen content in the as-cast slab is uniform, while the hydrogen content in the slab tends to
be higher near the surface than in the interior after annealing. Such a tendency becomes more marked
when annealing time is prolonged and Si and Fe content is lowered. The condensation of hydrogen
near the surface can be seen only when it is annealed in a wet atmosphere. When annealed in a dry
atmosphere, the hydrogen content near the surface becomes lower than in the center of the specimen.
The hydrogen in Al-Mg alloys tends to be released to outside intrinsically at temperatures around
400°C and above. It is revealed that oxide film formed on the surface prevents the hydrogen from
being released to outside.
The Combination of Modeling Techniques to Predict the Service Behaviour of Heat Resistant Alloys
Authors: Tancret Franck , Laigo Johanne
Published: March 2009

It is here demonstrated that combinations of various modeling techniques can be used to
predict the service behaviour of heat resistant alloys, and sometimes to design “made-to-measure”
alloys for specific high temperature applications. A first example is given, where an affordable
creep-resistant nickel-base superalloy for operation around 750°C has been designed without any
experiment. Based on the analysis of huge databases on existing alloys, Gaussian processes were
used to predict its thermomechanical properties. Thermo-Calc allowed to design its fabrication
process and to assess its weldability and its thermodynamical stability at service temperature. The
alloy has then been tested and the validity of the modeling approach verified a posteriori, in
particular a creep rupture life of 100 000 h at 750°C under 100 MPa. A second example is given, in
the case of high-carbon Fe-Ni-Cr based alloys for reformer tube applications (HP steels). Their
mechanical properties are predicted through the analysis of existing data with artificial neural
networks. Parallelly, their thermodynamical stability in operating conditions is assessed using
Thermo-Calc in combination with Dictra, to simulate the precipitation of carbides in the austenite
matrix during service. It is therefore tried to understand microstructural evolution in service,
damage mechanisms, and durability.
Phase Transformation and Microstructures in Ni and Cu Base Ferromagnetic Shape Memory Alloys
Authors: Kushima Takuro , Tsuchiya Koichi , Sho Yasuyoshi , Yamada Takafumi , Todaka Yoshikazu , Umemoto Minoru
Published: March 2009

Effect of chemical composition was investigated on martensitic transformation
temperatures, Curie temperature, magnetization and microstructures for Ni-(Mn, Fe, Co)-Ga and
Cu-Mn-Ga systems. In the Ni-(Mn, Fe, Co)-Ga alloys, which is a modification of Ni-Mn-Ga systems,
the Af and TC over 400 K were achieved. Cu-Mn-Ga alloy exhibited shape memory effect at
temperatures above 373 K and had TC over 400 K. Furthermore, Cu-Mn-Ga exhibits good ductility
even in polycrystalline condition unlike the case of Ni-Mn-Ga. Effect of addition of the fourth
element to improve the magnetic property is under investigation.
Fabrication Method for Metallic Closed Cellular Materials Containing Different Materials from that of Cell Walls by SPS Method
Authors: Kishimoto Satoshi , Shinya Norio
Published: March 2009

Several methods of fabricating metallic closed cellular materials a spark plasma sintering
(SPS) system have been developed. Powdered polymer particles coated with a nickel-phosphorus
alloy layer using electro-less plating were pressed into pellets and sintered at high temperatures in a
furnace using SPS system. Metallic closed cellular materials containing different materials from the
cell walls were then fabricated. The physical, mechanical and damping properties of these materials
were measured. The results of the compressive tests show that this material has different stressstrain
curves among the specimens that have different cell wall thicknesses and the sintering
temperatures of the specimens affect the compressive strength of each specimen. Also, it seems that
the results of the compressive tests show that this material has a high-energy absorption. The
internal friction of this material was measured and the results show that this internal friction is the
same as that of pure aluminum. These results suggest that this material can be utilized as an energy
absorbing and passive damping material.
Biodegradable Fiber Reinforced Ti Composite Fabricated by Spark Plasma Sintering Method
Authors: Sato Hisashi , Umaoka Seiichiro , Watanabe Yoshimi , Kim Ick Soo , Kawahara Masakazu , Tokita Masao
Published: March 2009

Ti and Ti alloys are particularly attractive materials as the metallic implant-material. This
is because that these alloys have low shear modulus and the good biological compatibility with bone.
However, interfacial adhesion ability of bone and Ti alloy is low. As improvement method of the
interfacial adhesion ability, bioaffinity material like hydroxyapatite has been coated on surface of the
Ti alloys. However, such bioaffinity materials have low strength and wear resistance. In this study, Ti
composites containing biodegradable poly-L-lactic-acid (PLLA) fiber were fabricated by spark
plasma sintering (SPS) method. The PLLA fiber plays a role as reinforcement in Ti matrix, and can
be gradually decomposed inside body with progress of time. By the decomposition of PLLA, pore is
generated in Ti matrix, and bone simultaneously penetrates into the pore. Therefore, tightly bond
between bone and Ti matrix can be expected. Using the Ti-PLLA composites fabricated by SPS
method, microstructural observation and mechanical tests were performed. It was found that
Ti-PLLA composite has laminate-layer structure with plate-like shape PLLA. Hardness and wear
behavior of Ti-PLLA composite has anisotropy due to its structure. However, strength of the
Ti-PLLA composite is low because of the imperfect sintering of Ti matrix. Since sintering of Ti
matrix can be improved by changing the temperature of SPS, Ti-PLLA composite with anisotropic
mechanical properties can be expected by SPS method.
New Application of Electromagnetic Vibration Process for Creation of High Potential Metallic Materials
Authors: Miwa Kenji , Mizutani Yoshiki , Tamura Takuya , Omura Naoki
Published: March 2009

We have developed the new process for refinement of metallic materials during
solidification without addition of refiners or without rapid cooling. This process uses
electromagnetic body force based on the vibrations caused by simultaneous imposition of direct
magnetic field and alternative electric current on the alloy melt during solidification. The
vibrations create cavitation in the melt and it breaks out during growth of it. Then explosive force
is released toward the surroundings such as the primary solid particles and they are fractured finely.
Finally fractured solid particles solidified as very fine grains.
This process was applied to hyper- and hypo-eutectic Al-Si alloys, and AZ91D Mg alloys.
Primary silicon crystals in Al-17mass%Si alloy decreased the size remarkably by the optimum
electromagnetic vibration condition. Primary aluminum dendrites particles in Al-7mass%Si and
primary magnesium dendrite particles in AZ91D are also decreased its size markedly.
This process has also been applied to create non-equilibrium state metallic materials such as
metallic glasses. We have succeeded to obtain metallic glasses in Mg-Y-Cu alloy system and
Fe-Co-Si-B-Nb alloy system. These alloys solidified as fully crystals in this cooling rate without
electromagnetic vibrations. These glasses are bulky and are used as structural material.
Effect of Strain Rates on the Transformation Behavior of Ni-Ti Alloy
Authors: Date Hidefumi
Published: March 2009

In order to clarify the effect of strain rates on phase transformation behaviors of Ni-Ti alloy, a
compressive test using a cylindrical specimen of polycrystalline Ni-Ti alloy of Ti-50.69 at% Ni was carried
out at a high strain rate and a low strain rate. The transformation temperatures were determined by a
differential scanning calorimeter (DSC) using a sample cut from a compressed specimen. The transformation
temperatures of the specimens before deformation were Ms= 303 K, Mf = 287 K, As = 297 K and Af = 319 K,
respectively. The compressive test was carried out using specimen heated from liquid nitrogen temperature to
room temperature. A universal testing machine as a static test apparatus and a Split Hopkinson Bar apparatus
for a dynamic test were used. The specimen had a reoriented martensite phase after deformation because the
superelastic effect was not observed upon unloading. Two reverse transformations during heating and a
forward transformation during cooling were observed by DSC measurement. The first reverse transformation
corresponds to that of thermal-induced martensite by immersion in liquid nitrogen and the second reverse
transformation corresponds to that of reoriented martensite with slips in a polycrystalline matrix introduced
by plastic deformation. The reverse transformation of the martensite phase with a slip exhibited strong strain
rate dependency. Plastic strains and strain rate had strong influence on the shape recovery. The interaction
between the temperature elevation by a conversion of plastic work and slip generated by dynamic plastic
deformation is a complicated problem.
Enlarging the Temperature Range for Maximum Wear Resistance of TiNi Alloy Using a NTE Phase
Authors: Radu Iulian , Li Dong Yang
Published: March 2009

The near-equiatomic TiNi alloy has been demonstrated to possess high wear resistance,
which largely benefits from its pseudoelasticity (PE). However, the PE occurs only in a small
temperature range, which makes the wear resistance of this alloy unstable as temperature changes,
caused by environmental instability or frictional heating. Therefore, enlarging the working
temperature of PE could considerably improve this alloy as a novel wear-resistant material.
One possible approach is to develop a self-built temperature-dependent internal stress field by
taking the advance of the difference in thermal expansion between the pseudoelastic matrix and a
reinforcing phase. Such a T-dependent internal stress could adjust the martensitic transformation
temperature to respond changes in environmental temperature so that the temperature range of PE
could be enlarged, thus leading to a wide temperature range in which the minimum wear loss is
retained.
Research was conducted to investigate effects of an added second phase having a negative
thermal expansion (NTE) coefficient on the wear resistance of a near-equiatomic TiNi alloy. It
was demonstrated that the temperature range of this modified material in which the wear loss
dropped was enlarged. In addition, the wear resistance of such a TiNi-matrix composite was on
one order of magnitude higher than that of unmodified TiNi alloy.