bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal Fatigue Characteristics of Heat-Resisting Stainless Steel for Automotive Exhaust
Authors: Ha Tae Kwon , Sung Hwan Jin
Published: March 2009

Thermal fatigue is a complex phenomenon encountered in materials exposed to cyclically
varying temperatures in the presence or absence of external load. Continually increasing working
temperature and growing need for greater efficiency and reliability of automotive exhaust require
immediate investigation into the thermal fatigue properties especially of high temperature stainless
steels. In this study, thermal fatigue properties of 304 and 429EM stainless steels have been evaluated
in the temperature ranges of 200-800oC and 200-900oC. Systematic methods for control of
temperatures within the predetermined range and measurement of load applied to specimens as a
function of temperature during thermal cycles have been established. Thermal fatigue tests were
conducted under fully constrained condition, where both ends of specimens were completely fixed.
Thermal fatigue property of STS 304 was superior to that of STS 429EM. Load relaxation behavior at
the temperatures of thermal cycle was closely related with the thermal fatigue property.
Influence of the Shot Peening Process on the Fatigue Behaviour of Duplex Stainless Steel Reinforcing Bars
Authors: Real Enrique , Rodríguez Cristina , Fernández Canteli A. , Belzunce F.Javier
Published: March 2009

The influence of shot peening on the fatigue properties of duplex stainless steel
reinforcing bars manufactured using both hot and cold rolled processes was studied. From
determination of the S-N curves, the experimental results show that shot peening improves the
fatigue behaviour of the re-bars, but that the improvement is much greater for the hot rolled
bars. A more severe peening action capable of promoting greater plastic deformation of the
bar surface needs to be used to improve the fatigue resistance of cold rolled corrugated bars.
Nanostructured Shape Memory Alloys for Biomedical Applications
Authors: Tsuchiya Koichi , Cao Qi Feng , Hosokawa Akihide , Katahira Masayuki , Todaka Yoshikazu , Umemoto Minoru
Published: March 2009

Application of TiNi shape memory alloy in biomedical field is rapidly expanding. Some of
the applications calls for non-conventional properties, which may require new methods of
thermomechanical treatment and surface modification. In the present study, the effect of
nanocrystallization/amorphization by various method of severe plastic deformation, such as, shot
peening, cold rolling and high pressure torsion, was investigated on properties of TiNi shape memory
alloys. Shot peening using iron based metallic glass media was found to be an effective method to
obtain the amorphous surface. Surface amorphization improved the corrosion resistance.
Nanocrystalline TiNi exhibited peculiar superelastic properties. Correlation between the
microstructure and phase transformation in nanostructured TiNi was discussed.
A Prototype Continuous Flow Polymerase Chain Reaction LTCC Device
Authors: Moeller Korey , Besecker Jason , Hampikian Greg , Moll A. , Plumlee D. , Youngsman John , Hampikian Janet M.
Published: March 2009

There is a growing need for remote biological sensing in both laboratory and
harsh field environments. Sensing and detection of biological entities such as anthrax,
Ebola and other micro-organisms of interest involves sampling of the environment,
amplification, analysis and identification of the target DNA. A key component of such
a sensor is a low cost, portable, reusable, continuous flow polymerase chain reaction
(PCR) thermal cycler. Fabrication with low temperature co-fired ceramics (LTCC)
can provide a reusable low cost device capable of operating in a wide range of
environments
The design and manufacture of a prototype continuous flow micro-fluidic PCR
device using low temperature co-fired ceramic is presented. Initial modeling of flow
characteristics and heat transfer was carried out in SolidWorks™. The prototype
device employs resistance heaters below the channels, buried and surface
thermocouples for temperature monitoring, and air gaps for thermal isolation.
Biofunctional Materials for Nerve Regeneration
Authors: Kim Yu Mi , Gao Jin , Zern Blaine , Wang Ya Dong
Published: March 2009

Most biomaterials widely used in nerve regeneration are either inert or modified with
ECM proteins or their epitopes. Neurotransmitters play a key role in neuronal development and
function. Thus we decided to investigate the feasibility of using neurotransmitters to create
biofunctional materials that actively engage nerve cells to achieve functional restoration after injury
of the nervous system. Our data indicated that a properly designed biodegradable polymer with
dopamine functional groups was more capable of promoting neurite growth. Such biofunctional
materials can potentially provide a new strategy for nerve regeneration.
Biofunctional Hybrid of Titanium with Polymers
Authors: Hanawa Takao , Sakamoto Harumi , Tanaka Yuta
Published: March 2009

Application of metals will be expanded to new medical devices, scaffold for tissue
engineering, artificial organs, etc. with the addition of biofunction. Therefore, immobilization or
combination of functional polymers to metals is significant subject for the application of metals to
biofunctional materials and sensors. Metal-polymer hybrid materials are promising biomaterials
future, especially for artificial organs. To form metal-polymer hybrid for biomedical devices, two
techniques are predominant according to the purpose: Immobilization of biofunctional polymers to
metals and bonding of biopolymers with metals. In the first case, poly(ethylene glycol: PEG) is a
biofuctional molecule on which adsorption of proteins is inhibited. Control of immobilization mode
of PEG modified with NH2 to titanium surface by electrodeposition is feasible and the adsorption of
proteins is inhibited by the deposited PEG. This technique could be applied to all metallic materials.
In the other case, we attempted to form a composite of titanium with segmentated polyurethane (SPU)
thorough silane-coupling agent (γ-MPS). This composite material is applied to texture of titanium
covered by SPU as artificial organs.
Gamma-Poly(glutamic acid)/Chitosan Composite Scaffolds for Tissue Engineering Applications
Authors: Tsai Sung Pei , Hsieh Chien Yang , Hsieh Chung Yu , Chang Yaw Nan , Wang Da Ming , Hsieh Hsyue Jen
Published: March 2009

The development of tissue engineering provides a novel approach to restore bodily
functions by seeding cells onto various scaffolds. Although chitosan is a non-toxic biomaterial, its
cytocompatibility still needs to be improved. In this study, gamma-poly(glutamic acid) (γ-PGA) was
blended with chitosan to prepare both dense and porous γ-PGA/chitosan composite scaffolds using
the freeze-gelation method. This method saves time and energy, and there is less residual solvent.
SEM micrographs demonstrated that an interconnected porous structure with a pore size of 30-100
micrometer was present in the scaffolds. The hydrophilicity of the scaffolds was significantly
improved by γ-PGA. Further, the tensile strength of the porous γ-PGA-modified chitosan scaffolds
was about 50% higher than that of the unmodified chitosan scaffolds. The number of osteosarcoma
cells cultured on the γ-PGA-modified scaffolds was about double that on the unmodified chitosan
scaffolds on day 7. Thus, the γ-PGA/chitosan composite scaffolds, due to their better hydrophilicity,
cytocompatibility, and mechanical strength, are very promising biomaterials for tissue engineering
applications. We further demonstrated the use of glutamic acid to enhance the tensile strength of
chitosan-based composite porous scaffolds. The tensile strength of the chitosan/collagen composite
scaffolds was increased by more than 2 times with the addition of glutamic acids as cross-linking
bridges. We found that the hepatocytes attached and proliferated well on these composite scaffolds,
demonstrating that the glutamic acid modified-chitosan composite scaffolds are also potential tissue
engineering biomaterials.
Preparation of Poly(Lactic Acid) Composites Containing Vaterite for Bone Repair
Authors: Kasuga Toshihiro , Obata Akiko , Maeda Hirotaka , Hench Larry L.
Published: March 2009

Calcium carbonate (vaterite)-containing poly(lactic acid) (PLA) composites (CCPCs)
were prepared for novel biomaterials that are expected to exhibit high bioresorbability and
osteoconductivity. CCPC containing 30% vaterite showed bending strengths of 40~50 MPa. 13C
CP/MAS-NMR spectrum of CCPC suggested the formation of a bond between Ca2+ ion and COOgroup.
The bond may play an important role in the improvement of the mechanical properties. On the
surface of CCPC containing 30 % vaterite, ~10-μm-thick hydroxycarbonate apatite (HCA) formed
after 1 day of soaking in SBF at 37oC. After 1-week incubation of human osteoblasts (HOBs) on the
HCA-coated CCPC, numerous HOBs attached. The adhesion of cells on the composite was greater
than that on PLA. After 3-week culture of HOBs on HA-coated CCPC, numerous bone nodules could
be seen on the surface. CCPC is believed to be one of the most promising materials for bone repair. A
novel CCPC containing polysiloxane was also prepared using aminopropyltriethoxysilane (APTES).
Polysiloxane partially assembled in the membrane and a molecular chain of PLA was bonded at the
end of an organic chain in APTES through the amide bond formed between carboxy groups in PLA
and amino groups in APTES. The composite formed HA on its surface after 3 days of soaking in SBF.
The HA layer included Si with Ca and P. The composite coated with silicon-containing HCA had
higher cell-proliferation ability than that without HA. The existence of silicon-containing HCA may
be apt to stimulate the proliferation.
Receptor-Mediated Gene Delivery Using Chitosan Derivatives In Vitro and In Vivo
Authors: Kim Tae Hee , Hua Jin , Kim Hyun Woo , Cho Myung Haing , Nah Jae Woon , Choi Yun Jaie , Cho Chong Su
Published: March 2009

The development of an efficient targeted gene delivery system into cells is an important
strategy for the advancement of gene therapy. The targeted gene delivery system is especially
important in non-viral gene transfer which shows the relative low transfection efficiency. And it also
opens the possibility of selective delivery of therapeutic plasmids to specific tissues. Chitosan has been
considered to be a good candidate for gene delivery system, since it is already known as a
biocompatible, biodegradable, and low toxic material with high cationic potential. However, low
specificity and low transfection efficiency of chitosan need to be overcome prior to clinical trial. In
this study, we focused on the chemical modification of chitosan for enhancement of cell specificity
and transfection efficiency.
Calcium Phosphate Precipitation by Galvanic Current between Titanium and Gold in Pseudo-Body Fluid
Authors: Kobayashi Equo , Ogo Masa , Doi Hisashi , Yoneyama T. , Noda K. , Hanawa Takao
Published: March 2009

For commercialized dental implants, to enhance the bone bonding of the artificial tooth
roots, several kinds of surface modification techniques, such as hydroxy-apatite coating, anodic
oxidation and sand-blasting, have been developed. Apart from the surface modification, it is known
that the bone growth is accelerated by electric stimulations in the living body. In the present study, the
galvanic current between titanium substrate and gold coating partially on the titanium implants was
applied to enhance calcium phosphate precipitation in a pseudo-body fluid namely Hanks’ solution.
The galvanic current between titanium specimens and gold electrode jumped up approximately 0.2 s
after put into Hanks’ solution and the current has decreased asymptotically. With such consideration,
the desirable conditions of surface modification by gold coating were presented to provide suitable
galvanic current density enhancing calcium phosphate precipitation.
Variation in Bone Quality during Regenerative Process
Authors: Nakano Takayoshi , Ishimoto Takuya , Umakoshi Yukichi , Tabata Yasuhiko
Published: March 2009

Since preferential orientation of c-axis of biological apatite (BAp) crystallites depends
strongly on the shape of hard tissue, closely relating to the in vivo stress distribution, it is a useful
parameter to judge the bone quality. In this study, preferential alignment of BAp crystallites in original
and regenerated hard tissues were analyzed by the micro-beam X-ray diffractometer (μ-XRD) with a
beam spot of 50 or 100 μm in diameter. Regenerating processes of bone defects introduced artificially
in the rabbit ulna or skull were healed by inserting a biodegradable gelatin hydrogel incorporating
basic fibroblast growth factor-2 (FGF-2).
Recovery of BAp orientation alignment depends strongly on the regenerated portion and period,
which is insufficient to recover the original level, while bone mineral density (BMD) is almost
improved to the original level. This means that BMD recovers prior to improvement of the BAp
orientation and the related mechanical function in the regenerated tissues. Thus, reloading on the
regenerated portion caused by BMD restoration is suggested to accelerate to produce the appropriate
BAp preferential alignment due to the remodeling process.
The BAp orientation was finally concluded to be one of the most important indices to check the
regenerative degree and process in the regenerated bone under the tissue engineering technique.
Formation and In Vitro and In Vivo Evaluation of Surface Modified Implants by HAp, Carbonated-HAp and Titanium Oxide
Authors: Okido Masazumi , Ichino Ryoichi , Kuroda Kotaro
Published: March 2009

Hydroxyapatite (Ca10(PO4)6(OH)2, HAp), carbonated HAp and titanium oxide are of
interest for bone-interfacing implant applications, because of their demonstrated osteoconductive
properties. They were coated on the titanium implants and investigated the in vitro and in vivo
performance. HAp coatings were performed by the thermal substrate method in aqueous solutions.
Titanium oxide film was also formed on the titanium implants by gaseous oxidation, or by anodizing
in the acidic solution. All the specimens covered with HAp, carbonated HAp or TiO2 (rutile or
anatase). were characterized by XRD, EDX, FT-IR and SEM. In the in vitro testing, the mouse
osteoblast-like cells (MC3T3-E1) were cultured on the coated and non-coated specimens for up to 30
days. Moreover, the osseointegration was evaluated from the rod specimens implanted in rats
femoral for up to 8 weeks. In in vivo evaluations two weeks postimplantation, new bone formed on
the coated and non-coated titanium rods in the cancellous bone and cortical bone, respectively.
Bone-implant contact ratio, in order to evaluate of new bone formation, was significantly depended
on the compound formed on the titanium implant.
High Temperature Deformation Behavior and Microstructure Change in Nano Grain Composites
Authors: Miyano Naoki , Kumagai Yusuke , Yoshimoto Masayoshi , Tanaka Shigeo , Isonishi Kazuo , Ameyama Kei
Published: March 2009

One of the authors proposed a non-equilibrium powder metallurgy process, which
enables the fabrication of a near net-shape product using TiC and TiN/Silicide ceramic composites.
The PM process in combination with mechanical alloying (MA) and Spark Plasma Sintering (SPS)
are applied to produce nano-grain composite, TiC/Ti5Si3. Powders of elements Ti and SiC whose
composition is Ti-20 mass%SiC are blended for MA. After the alloying, the MA powder whose
average particle size is 20~30 μm, has amorphous-like structures, and then the MA powder is
compacted by SPS. Results of compression-tests indicate the occurrence of unusual hightemperature
deformation behaviors such as low flow stress at the lower deformation temperature or
at the high initial strain rates were observed in the SPS compacts. TEM observations of the
deformed compacts after the compression-tests indicate the microstructure has no-strain equiaxial -
grains and clear boundaries. This serves as proof of a superplasticity deformation. In addtion, the
results of the XRD analysis of the compressed-compacts show that new phases are formed during
the compression-test. Therefore, the above deformation is attributed to a "pseudo" superplasticity in
which the phase transition of metastable microstructure occurs during the deformation.
Polymer Nanocomposites as Candidates for Tribological Applications
Authors: Zhang Ming Qiu , Rong Min Zhi , Friedrich Klaus
Published: March 2009

To develop wear resistant nanocomposite coating materials, the authors treated nanosilica
first by introducing a certain amount of grafting polymers onto the particles in terms of an irradiation
technique. Through irradiation grafting, the nanoparticle agglomerates turn into a nano-composite
microstructure, which in turn built up a strong interfacial interaction with the surrounding epoxy
matrix during the subsequent mixing and consolidation. The experimental results indicated that the
addition of the grafted nanosilica into epoxy significantly reduced wear rate and frictional coefficient
of the matrix at low filler loading. Compared with the cases of microsized silica and untreated
nanosilica, the employment of grafted nanosilica provided the composites with much higher
tribological performance enhancement efficiency.
Analysis of Fine Stress Fields in Metal Matrix Composites Using HOLZ Patterns
Authors: Shibata M. , Takemoto Yoshito , Shimizu Ichiro
Published: March 2009

Aluminium alloy composites reinforced with aluminium borate whiskers (ABw), developed recently
by SHIKOKU KASEI KOUGYOU Co. Ltd., Japan, were fabricated using squeeze casting.
The large mismatch in the coefficients of thermal expansion (CTE) between the reinforcement
material and the matrix can generate significant stress and strain in composites during thermal cycling
or during fabrication of the composites when using squeeze casting. When a transmission
electron microscope is used to irradiate a very small area of a thin film of the material with a convergent
electron beam of several nm in diameter, High Order Laue Zone patterns (HOLZ patterns)
are obtained. These HOLZ patterns can reveal fine strain fields in the reinforcement materials that
are used in composites fabricated using squeeze casting. Each (001) plane in the ABw was rotated
towards the [020] direction by up to 0.5 ﾟ. With a unit of nearly 400 nm × 400 nm, each (100)
plane was rotated towards the [020] direction in a corkscrew pattern. In addition the strain and the
stress generated during the fabrication of the composites were estimated by using the finite element
methods taking into account the anisotropies in both the CTE and the elastic modulus of the
reinforcement material.
Fabrication of Nano-Laminar Glass/Metal Composites by Sintering Glass Flakes
Authors: Kakisawa Hideki , Minagawa Kazumi , Takamori Susumu , Osawa Yoshiaki
Published: March 2009

Fabrication of nano-laminar ceramic composite by a simple sintering technique was
examined. Glass flakes with a thickness of 0.7μm coated with silver were used as model materials,
and were consolidated by pulsed current sintering with a uniaxial press of 7.1MPa or 30MPa. By
sintering the flakes at 943K, we obtained a fairly dense composite where the flakes were aligned by
uniaxial press. The silver coating remained on the flakes through the sintering, and an interface layer
between the flakes was formed. The sample’s indentation test demonstrated its high resistance to
crack propagation through the transverse direction of the lamellar; this result was attributed to crack
deflection at the interface and the accumulation of microfractures around the indentation mark.
Syntheses and Applications of Fe-, Co-, Ni- and Cu-Based Bulk Glassy Alloys
Authors: Inoue Akihisa , Shen Bao Long , Takeuchi Akira
Published: March 2009

This paper reviews our recent results of the formation, fundamental properties,
workability and applications of late transition metal (LTM) base bulk glassy alloys (BGAs)
developed since 1995. The BGAs were obtained in Fe-(Al,Ga)-(P,C,B,Si), Fe-(Cr,Mo)-(C,B),
Fe-(Zr,Hf,Nb,Ta)-B, Fe-Ln-B(Ln=lanthanide metal), Fe-B-Si-Nb and Fe-Nd-Al for Fe-based alloys,
Co-(Ta,Mo)-B and Co-B-Si-Nb for Co-based alloys, Ni-Nb-(Ti,Zr)-(Co,Ni) for Ni-based alloys, and
Cu-Ti-(Zr,Hf), Cu-Al-(Zr,Hf), Cu-Ti-(Zr,Hf)-(Ni,Co) and Cu-Al-(Zr,Hf)-(Ag,Pd) for Cu-based
alloys. These BGAs exhibit useful properties of high mechanical strength, large elastic elongation
and high corrosion resistance. In addition, Fe- and Co-based glassy alloys have good soft magnetic
properties which cannot be obtained for amorphous and crystalline type magnetic alloys. The Feand
Ni-based BGAs have already been used in some application fields. These LTM base BGAs are
promising as new metallic engineering materials.
Stacking Faults and Growth Mechanism of In Situ TiB Whiskers and Interface Structures in SPSed TiB/Ti(FeMo) Composites
Authors: Zhou Yu , Feng Hai Bo , Jia De Chang , Meng Qing Chang
Published: March 2009

In situ TiB whiskers reinforced Ti metal matrix composites have been fabricated by spark
plasma sintering (SPS). Microstructure and stacking faults of in situ TiB whiskers in the composites
were investigated in detailed by means of scanning electron microscopy (SEM), transmission
electron microscopy (TEM) and high-resolution electron microscopy (HREM). The TiB whiskers
exhibit a hexagonal shape at the transverse section and grow along the [010]TiB direction. The
crystallographic planes of the TiB whiskers at transverse section are always of the (100), (101) and
(10 1 ) planes. The interfaces between the in situ TiB and Ti matrix are clean and faceted along
(100)TiB side. However, small lateral growth steps are observed along (101) and (10 1 ) planes of
TiB. The stacking faults in TiB whiskers are typically with a stacking fault plane of (100)TiB and
displacement vectors of 0.5a±0.254c. The formation mechanism of stacking faults has been
proposed and verified by HREM observations.
A Novel Forming Process of Copper Cladding Aluminum Composite Materials with Core-Filling Continuous Casting
Authors: Xie Jian Xin , Wu Chung Jing , Liu Xue Feng , Liu Xin Hua
Published: March 2009

To simplify forming process of cladding materials with high performance, such as copper
cladding aluminum composite materials, and to improve the interface quality of cladding materials,
a novel forming process called Core-Filling continuous Casting (CFC) for bimetal composite
materials is proposed. A conceptual equipment is developed, and the forming of composite bars of
copper cladding aluminum is investigated. The basic technique theory of CFC, the reaction and
bonded state of interface and the interfacial bonding strength of the cladding materials, as well as
the influences of technological parameters are analyzed. The composite bars of copper cladding
aluminum with 24mm in diameter of core material and 8mm in thickness of cladding layer are
successfully fabricated. The results show that: (i) the proposed CFC process is feasible in principle;
(ii) the composite bars of copper cladding aluminum having metallurgical bonding interfaces can be
fabricated by CFC process under the conditions of liquid copper temperature of 1250~1300°C,
liquid aluminum temperature of about 700°C and drawing velocity of 12~24mm/min; (iii) the
copper layer thickness distribution is uniform both in the directions of portrait and circumference
and (iv) the interfacial bonding strength is higher than that of core aluminum.
Creep Properties of Alborex Reinforced AZ31 Matrix Mg Composites Containing Ag
Authors: Hwang Sung Doo , Park Yong Ha , Song Dae Hyun , Lee Man Sik , Cho Kyung Mok , Park Ik Min , Park Yong Ho
Published: March 2009

AZ31 Mg alloy matrix composites were fabricated by squeeze casting method to improve
high temperature properties in this study. The results showed that Mg composites reinforced with
Alborex and Ag revealed improved high temperature properties and mechanical properties compared
with Mg alloys. High temperature hardness and flexural strength were increased with reinforcement
of Alborex, and further increase was obtained with addition of Ag. Also, Alborex reinforced AZ31
containing Ag Mg matrix composite exhibited greater improvement on creep properties. Therefore
Mg composites reinforced with Alborex containing Ag were better than those reinforced with
Alborex in mechanical properties and high temperature properties.
Evaluations of Microstructure and Hydrogenation Properties on Mg2NiHx Hydrogen Absorbing Alloys by Hydrogen Induced Mechanical Alloying
Authors: Kim Whan Gi , Ur Soon Chul , Lee Y.G. , Kim Young Jig , Hong Tae Whan
Published: March 2009

In order to fabricate high efficiency, light-weight hydrogen storage materials in an
economical way, we have been made to propose a new mechanical alloying process by high-pressure
hydrogen induced planetary ball milling(HIMA) using Mg and Ni chips. Microstructural evaluations
of the Mg-Ni-H systems synthesized were investigated by scanning electron microscopy and the
transmission electron microscopy. X-ray diffraction analysis was also made to characterize the lattice
constant, crystallite size and misfit strain. The hydrogenation properties of the particles synthesized
were evaluated by automatic PCI (pressure-composition-isotherm). Adopting 66:1 BCR (ball to chips
mass ratio) for HIMA process, fully hydrogenated alloys were obtained after 96 hrs of milling,
resulting in total hydrogen content of 2.25 mass%.
Microstructure and High Temperature Mechanical Properties of Inconel 617
Authors: Jo Tae Sun , Kim Gil Su , Seo Young Ik , Ryu Woo Seog , Kim Young Do
Published: March 2009

Inconel 617 is a candidate tube material for high temperature gas-cooled reactors
(HTGR). The microstructure and mechanical properties of Inconel 617 were studied after exposure
at high temperature of 1050oC. The dominant oxide layer was Cr-oxide. The internal oxide and Crdepleted
region were observed below the Cr-oxide layer. The major second phases are M23C6 and
M6C types of carbides. The composition of M23C6 and M6C were determined to be Cr21Mo2C6 and
Mo3Cr2(Ni,Co)1C, respectively, by EDS. These carbides are coarsened during exposure. M6C
carbide is more stable than M23C6 at high temperature. There was not much change in mechanical
properties after exposure at 1050oC for 1000 h.
Thermoelectric Properties of Skutterudite CoSb3 Prepared by Encapsulated Induction Melting
Authors: Ur Soon Chul , Kim Il Ho
Published: March 2009

Encapsulated induction melting was attempted to prepare binary skutterudite CoSb3 and its thermoelectric properties were investigated. Single phase δ-CoSb3 was successfully obtained by the subsequent isothermal heat treatment at 773K-873K for 24 hours in vacuum. Thermoelectric properties were changed with constituent phases because β-CoSb and Sb are metallic/semimetallic phases, while γ-CoSb2 and δ-CoSb3 are semiconducting phases. Thermoelectric properties were remarkably improved by the proper heat treatment and they were closely related to phase transitions.
Temperature Dependence of High-Cycle Fatigue Behavior of a Ni-Base Single Crystal Superalloy
Authors: Liu Y. , Yu Jin Jiang , Xu Yan , Sun Xiao Feng , Guan Heng Rong , Hu Zhuang Qi
Published: March 2009

Smooth specimens of single crystal (SC) superalloy SRR99 with [001] orientation were subjected to high-cycle fatigue (HCF) loading at temperatures of 700°C, 760°C, 850°C and 900°C in air atmosphere. The results demonstrated that conditional fatigue strength reached the maximum at 760°C and decreases with increasing temperature. Analysis on fracture surface showed a trend for cleavage rupture at 850°C and 900°C and ductile rupture at 700°C and 760°C. Fatigue cracks initiated at the surface or subsurface were primarily responsible for the ultimate failure. The influence of testing temperature on fatigue lifetime was studied by examining evolution of the microstructure through SEM observation. With the process of cyclic loading at elevated temperatures, the primary cuboidal γ′ precipitates tended to agglomerate and spheroidized, meanwhile a larger number of secondary γ′ particles were formed in the γ matrix in specimens fatigue tested at 700°C, which would have a significant effect on the high temperature properties.
Development of a τ-Type Mg-Zn-Al Alloy: An Investigation of the Microstructure and Solidification Characteristics
Authors: Zhang Jing , Pan Fu Sheng , Guo Z. Xiao
Published: March 2009

The practical phase constituent diagram has been used to determine the composition of a
low alloying τ-type Mg-Zn-Al alloy, which has a nominal element content of 7wt%Zn and 3wt%Al
(ZA73), as a basis for further improvement of τ-type alloy through appropriate thermal processing and
micro-alloying. The microstructure and solidification characteristics of the alloy have been
experimentally examined using optical microscopy, scanning electron microscopy, X-ray diffraction,
and differential scanning calorimetry analysis. The results confirm that the as-microstructure of ZA73
alloy consists of globular equiaxed dendrite with τ phase as the only secondary phase evenly
distributed in interdendritic spacing. Solidification sequence has been proposed with the help of DSC
analysis and Mg-Zn-Al ternary liquidus projection phase diagram. Consistent with previous observed
results for τ-type Mg-Zn-Al alloy, due to the decrease of element contents, ZA73 alloy has higher
liquidus temperature (~627°C) and wider solidification range (~283°C), while at the mean time lower
starting temperature of the second phase transformation (~354°C), compared to higher element
containing ZA104 alloy. The phase constituent diagram has been shown to be a practical and effective
tool for predicting the as-cast microstructural constituent of high zinc Mg-Zn-Al alloys under normal
permanent mould solidification condition.
Pores in PAN-Based Carbon Fiber and Effects of Pore Defects on Mechanical Properties
Authors: Hua Zhong , Zhong Ya Juan , Li Dong Feng
Published: March 2009

Specimens of polyacrylonitrile-based carbon fiber (PAN-CF) with different graphitization
temperatures were investigated by small angle X-ray scattering (SAXS) and wide angle X-ray
diffraction (WAXD). Based on SAXS intensity data and fractal theory, surface fractal dimension of
the pore in PAN-CF was given by small angle X-ray scattering intensity method, the size of various
pores and the bigger pore percentage of unit volume were calculated by Fankuchen gradual tangent
method. The result indicatesd that the size and surface fractal dimension of the pores, the bigger pore
percentage of unit volume increased with increasing graphitization temperature. This forms stress
concentration easily, which leads to the decreasing of tensile strength.
Elevated Temperature Mechanical Behavior of Mg-Y-Zn Alloys
Authors: Chen Bin , Lin Dong Liang , Zeng Xiao Qin , Lu Chen
Published: March 2009

The elevated temperature mechanical behavior of Mg-Y-Zn alloys was investigated. It was
found that the extruded Mg-Y-Zn alloy exhibited excellent mechanical properties both at ambient
temperature and elevated temperature. With the increase of tensile temperature, the ultimate tensile
strengths of Mg-Y-Zn alloys decreased and their elongations increased. The ultimate tensile strengths
increased and elongations decreased with the increase of yttrium content. However, a gradual
increase in the ultimate tensile strength and elongation both at ambient temperature and elevated
temperature was obtained by increasing both yttrium and zinc contents. The fracture modes of
Mg-Y-Zn alloys at different tensile temperature were also investigated.
Homogenization Treatment of an Al-Li-Cu-Mg-Mn-Zr Alloy
Authors: Wei Xiu Yu , Zheng Zi Qiao , Chen Qiu Ni , Fu Xin
Published: March 2009

A systematic homogenization treatment on Al-Li-Cu-Mg-Mn-Zr alloy, within the
temperature range from 500C to 540C for 24h or 36h was conducted. Microstructure and alloying
elements distribution before and after homogenization treatment were studied by optical microscope,
SEM, EDS and XRD. The results showed that in the as-cast condition Cu segregated at grain
boundary and formed θ(Al2Cu) phase. With the homogenization temperature increased and time
prolonged, the amount of the remained particles at grain boundaries decreased, and the alloying
elements distribution became more homogeneous. It has been found that the homogenization
temperature has more obvious effects on the microstructure and mechanical properties than time.
However, the alloy homogenized at temperatures above 540C was overheated. Furnace cooling
generates large amounts of precipitates in the matrix. The best homogenization parameter of the
Al-Li-Cu-Mg-Mn-Zr alloy was determined as 530C for 24 h followed by air cooling.
TEM Investigation of Dislocations in Hot Deformed Mg-Al-Zn Alloy
Authors: Kochubey A.Ya. , Serebryany Vladimir , Timofeev V.N.
Published: March 2009

Ductility of Mg – alloys is linked to a shortage of independent slip systems. Basaltextured samples of Mg-Al-Zn alloy are examined for presence of dislocations of different types after hot compression tests of cast samples and cold compression tests of hot-rolled samples. The JEM-1000, electron transmission microscope with an accelerating voltage of 750 kV using a dark field–weak beam method of observation and the g·b=0 invisibility criterion as a basic method of the analysis of Burgers vectors, is used to analyse the samples. Dislocations with Burgers vectors , [c] and  are found. The results are used to evaluate the dislocation density and determine the possible dislocation reactions.
Characterization of Boundary Misorientations in a Superplastic Al-Alloy Hot-Deformed by ECAE
Authors: Mishin O.V. , Godfrey Andrew
Published: March 2009

Microstructure and boundary populations were investigated in a superplastic Al-5.5%Mg- 2.2%Li-0.12%Zr alloy hot-deformed by equal channel angular extrusion. The microstructure was found to be inhomogeneous and revealed deformation structures being subdivided by both low- and high-angle boundaries.
Evolution of the Grain Boundary Network as a Consequence of Deformation and Annealing
Authors: Randle Valerie , Coleman Mark , Owen Gregory
Published: March 2009

Iterative processing, involving sequential deformation and annealing, has been carried out on
copper specimens with the aim of grain boundary engineering (GBE) them. The data have provided
some interesting insights into the mechanisms of GBE. The results have demonstrated that development
of a high proportion of Σ3s is beneficial to properties, as shown by improved strain-to-failure for the
same strength. The proportion of Σ3s saturates at approximately 60% length fraction. Analysis of the
data indicates that iterative processing is not always necessary for the development of beneficial
properties, and it is further suggested that the condition of the starting specimen has a large influence on
the subsequent microstructural development. The present, new data are also compared with previous
research on copper where all five parameters of the grain boundary network population have been
measured.
Orientation Selection in ULC Steel during Thermally Activated Phenomena Induced by Cold Deformation
Authors: Verbeken Kim , Kestens Leo
Published: March 2009

The scope of this work was to study the physical metallurgical behaviour of the microstructure and the texture of ultra low carbon (ULC) steel during cold rolling and subsequent thermally activated phenomena. It was the intention to contribute to the scientific search for the answer to many open questions raised in recent literature. The powerful tool of quantitative texture analysis, together with modern measurement equipment was used for this purpose. At first, a ULC steel was cold rolled to two different rolling reductions and the local strain heterogeneities after the cold rolling were studied. Secondly, crystallographic orientation selection during primary recrystallization was considered both for cold rolled ULC steel and for a Fe-2.8%Si single crystal. The latter was a re-evaluation of the historic growth selection experiment by Ibe and Lücke. Finally, secondary recrystallization in ULC steels was evaluated in terms of oriented nucleation and selective growth.
On the Viability of FIB Tomography for Generating 3-D Orientation Maps in Deformed and Annealed Metals
Authors: Ferry Michael , Xu Wan Qiang , Mateescu Nora , Cairney Julie M. , Humphreys John F.
Published: March 2009

A typical dual-beam platform combines a focussed ion beam (FIB) microscope with a field emission gun scanning electron microscope (FEGSEM). Using this platform, it is possible to sequentially mill off > ~ 50 nm slices of a material by FIB and characterise, at high resolution, the crystallographic features of each new surface by electron backscatter diffraction (EBSD). The successive images can be combined to generate 3-D crystallographic maps of the microstructure. This paper describes various aspects of 3-D FIB tomography in the context of understanding the microstructural evolution of metals during deformation and annealing. The first part of the paper describes the influence of both metal type and milling parameters on the quality of EBSD patterns generated from a surface prepared by FIB milling. Single crystals of some face centred cubic metals were examined under varying FIB milling parameters to optimise EBSD pattern quality. It was found that pattern quality improves with increasing atomic number with the FIB milling parameters needed to be adjusted accordingly. The second part of the paper describes a useful technique for FIB milling for the reliable reconstruction of 3-D microstructures using EBSD. There is an initial procedure involving extensive milling to generate a protruding rectangular-shaped volume at the free surface. Serial sectioning is subsequently carried out on this volume. The technique was used to investigate the recrystallization behaviour of a particle-containing nickel sample, which revealed a number of features of the recrystallizing grains that are not clearly evident in 2-D EBSD micrographs.
Heterogeneous Deformation and Internal Stresses Developed in BCC Wires by Axisymmetric Elongation
Authors: Gil Sevillano J. , González D. , Martínez-Esnaola J.M.
Published: March 2009

BCC wires macroscopically deformed by axisymmetric elongation (wire drawing)
develop an intense <011> fibre texture and exhibit a characteristic non-uniform deformation of the
grains evident in transverse sections (grain curling or “Van Gogh sky structure”). The extraordinary
grain morphology induced by the <011> fibre texture is also accompanied by a peculiar constant
strain hardening rate in single-phase BCC wires (exponentially increasing in case of BCC
containing composite wires) that allows to reach very high strengths. Here we present a calculation
of the elastoplastic axial elongation of such an aggregate of BCC grains with the ideal <011> fibre
texture, using a slip-gradient dependent large-strain crystal plasticity constitutive equation
incorporated into a finite element method (FEM) code, i.e., with proper account of the influence of
the evolving shape and size of individual grains and of the local grain interactions. The results
reproduce well the observed macroscopic behaviour (linear flow stress-strain curve at large strains)
and the peculiar mesoscopic structural changes (grain curling in transverse sections). The simulation
is focused on the analysis of strain and dislocation density heterogeneities and on the building up of
mesoscopic (inter- and intra-granular) internal stresses during deformation. The computed average
transverse tensile stresses acting normal to the axially oriented {100} planes approximately parallel
to the boundaries of the flattened grains is close to 0.3 times the tensile flow stress of the aggregate,
in good agreement with previous calculations based on the Taylor-Bishop-Hill model or on elasticplastic
self-consistent calculations and with available neutron diffraction measurements. Such a high
level of internal tensile stresses explains the well-known tendency of high strength BCC wires to
fail by longitudinal splitting.
Estimation of the Heat Flux Through Furnace Side Walls Protected with Water Cooled Cooling Devices
Authors: Plascencia Gabriel , Utigard Torstein A. , Gutiérrez Juliana , Jaramillo David , Mayagoitia Vicente , Hernández-Pichardo Marcello L.
Published: March 2009

A three dimensional numerical heat transfer model has been developed to estimate the
heat flux trough furnace side walls protected with water cooled cooling fingers. The model was set
up by means of the finite element method. Materials with different thermal conductivity were
modelled and the results obtained with the mathematical model were compared with experimental
data. In every case, it was found excellent agreement between the experimental data and the model
computations.
Effect of Micron and Nano Size Oxide Material Additives on Reaction Sintering, Micro Structural and Physical Properties of Al2TiO5 Based Ceramics
Authors: Naderi Golsa , Shokuhfar Ali , Rezaie Hamid Reza , Naghizadeh Rahim , Shokuhfar Tolou
Published: March 2009

Aluminum-titanate (tialite) based ceramics have found widespread applications due to
their good thermal shock resistance and low thermal expansion. Tialite is presently used in
automotive industry, thermal processing technology, metallurgy and glass industry. Eutectoid
decomposition in to the initial oxides and low mechanical strength limit the well-known properties
of aluminum-titanate. In the present work, good stabilizing behavior was achieved by addition of
talc in micron size and appropriates properties were obtained by adding nano boehmite and
colloidal silica that results mullite phase formation. The effect of mullite phase in the densification
of tialite has been studied. XRD, DTA and SEM have been used to characterize the influence of
these additives on phase transformation, sintering process and microstructure.
Finite Element Analysis of Temperature and Density Distributions in Selective Laser Sintering Process
Authors: Dong Lin , Makradi Ahmed , Ahzi Saïd , Remond Yves
Published: March 2009

In the selective laser sintering (SLS) manufacturing technique a pre-heated layer of
material powder undergoes a laser radiation in a selective way to produce three dimensional
metallic or polymeric solid parts. Here, we consider sintering of polymer powder. The phase
transformation in this process involves the material heat transfer which is strongly affected by the
material sintering phenomena. A transient three dimensional finite element model is developed to
simulate the phase transformation during the selective laser sintering process. This model takes into
account the heat transfer in the material (powder and solid), the sintering and the transient nature of
this process. The numerical simulation of the set of equations, describing the problem, is made
possible by means of the commercial finite element software Abaqus. A bi-level structure
integration procedure is chosen, in which the density is integrated at the outer level and the heat
equation is integrated in the inner level. After successfully computing the integration of the density,
a material Jacobian representing the thermal phenomena is computed and supplemented the Abaqus
Code via an implicit user subroutine material. Results for temperature and density distribution,
using a polycarbonate powder, are presented and discussed.
Evaluation of Transmission Conditions for a Thin Heat-Resistant Inhomogeneous Interphase in Dissimilar Material
Authors: Mishuris Gennady , Miszuris Wiktoria , Öchsner Andreas
Published: March 2009

Imperfect transmission conditions modelling a thin intermediate layer between two
bonded materials in a dissimilar strip are derived in this paper. The interphase material is
assumed to be heat-resistant and situated in a thin rectangular domain between the main
materials. Different types of the interphase are investigated: homogeneous and inhomogeneous;
linear and nonlinear ones.
Modeling and Investigation of SiGe Based MOSFET Structure Transport Characteristics
Authors: Lukić P.M. , Ramović R.M. , Šašić Rajko M.
Published: March 2009

The focus of this paper was the investigation and modeling of transport characteristics in
a strained SiGe based MOSFET structure, which might be of fundamental importance for the
understanding of its operating characteristics. In the investigation, carrier mobility dependence on
the lateral and vertical electric field is especially considered. Carrier mobility models for long
channel as well as short channel SiGe MOSFETs are also presented. Average effective electric field
model is proposed taking into account impact of high electric field effects on the effective channel
length. In the final effective carrier mobility model, for the short channel SiGe MOSFETs, serial
drain to source resistance is included. At the same time, proposed models are relatively simple. By
using the presented model, simulations were performed.
N-Type Silicon Electron Mobility and its Relationship to the Kink Effect for Nano-Scaled SOI NMOS Devices
Authors: Sarajlić M. , Ramović R.M.
Published: March 2009

Electron mobility for the silicon-based devices is one of the most important parameters,
which determine the behavior of components. Mobility depends on silicon purity, doping level,
presence of lattice defects and electric field in the particular device. These influences are
particularly important for the nano-scaled devices since it is much more difficult to control the
thickness of the active layer, uniformity of impurity doping and appearance of parasitic bipolar
devices and capacitances. We have investigated a relationship between the electron mobility for the
silicon based PD (Partially Depleted) SOI (Silicon On Insulator) NMOS (n-type Metal Oxide
Semiconductor) Devices and the related kink effect, which appears as a consequence of the charge
accumulation at the interface of the Buried Oxide. We relate PD SOI NMOS Device technology
parameters to the kink effect and we propose a guiding line for alleviating this effect.
Electron Attachment to Metallic Clusters
Authors: Tančić A.R. , Davidović M. , Sredić S.
Published: March 2009

The calculations of the low-energy attachment cross section to metallic clusters are
investigated. Low energy electrons are taken as slow enough to excite a giant dipole collective
resonance within the cluster. The calculations are more refined than the earlier ones – they do not
depend on the experimental data, and we improved RPAE calculation of the collective resonance in
the cluster. The results are interesting for the nano-region and designing of new materials.
Some Properties of the Glass Transition in the Amorphous Sb-As-S-Se-I System
Authors: Skuban F. , Lukić S.R. , Petrović D.M. , Šiljegović Mirjana
Published: March 2009

Transformations of glasses from the multicomponent pseudobinary system
(As2Se3)100−x(SbSI)x were analyzed from the aspect of determining the glass transition temperature
Tg, activation energy of the process Et, and characteristic changes of the specific heat. The
established dependence of Tg on glass composition and heating rate served as the basis for
determining the activation energy of glass transition process Et. An abrupt increase in the specific
heat cp at the glass transition temperature was analyzed with the aim of classifying the materials
according to the criterion of the so-called 'fragility'. It was found that the investigated glasses, i.e.
their melts, belong to the group of thermodynamically 'strong' melts.