bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of GaP Nanowires Synthesized by Chemical Vapor Deposition
Authors: Cho Kwon Koo , Choi Kyo Hong , Kim Ki Won , Cho Gyu Bong , Kim Yoo Young
Published: March 2009

Gallium phosphide nanowires were successfully synthesized by the catalytic chemical vapor deposition (CVD) method using MgO powder-impregnated nickel oxide as catalyst and gallium phosphide and gallium powders as GaP source. The synthesis of GaP nanowires were carried out at 900°C for 30min under argon ambient and directly vaporized Ga and GaP powder. The diameter of GaP nanowires is about 25~70nm and the length is up to several tens of micrometers. The GaP NWs was core-shell structure, which consists of the GaP core and the Ga oxide outer layers. The GaP nanowires have a single-crystalline zinc blend structured crystals with the [111] growth direction. Nanowires larger than around 50nm in diameter exhibited twinning faults, which appears in the TEM images as discrete dark lines and alternating wire contrast. We demonstrate that MgO powder-impregnated nickel oxide catalyst exhibited a large catalytic effect on the growth of high-purity and -quantity gallium phosphide(GaP).
Numerical Simulation and Forecasting of Mechanical Properties for Multi-Component Nonferrous Dispersion-Hardened Powder Materials
Authors: Ryabicheva Lyudmila , Usatyuk Dmytro
Published: March 2009

A new mathematical simulation technique for physico-mechanical properties of multicomponent
powder materials is proposed in this paper. The main advantage of the technique is that
finite elements representing different components are placed into a common mesh and may
exchange their properties. The input data are properties of components and specified value of
porosity. The output data are properties of material after sintering. The technique allows us to
investigate the influence of each component of a material on the properties and distribution of
properties inside the sample. The comparative analysis of materials with different compositions is
based on simulation results that are well concordant with the results of the laboratory experiments.
An Investigation on the Sintering Behavior of High Strength Al-Zn-Mg-Cu Alloy Prepared from Elemental Powders
Authors: Shahmohammadi Maziar , Simchi Abdolreza , Danninger Herbert , Arvand A.
Published: March 2009

In the present work, the sintering behavior of high strength Al-5.6Zn-2.5Mg-1.6Cu (in
wt.%) alloy compacts was investigated. Green parts made by pressing of mixed elemental powders
were sintered at different temperatures between 400 and 600 °C. The effect of the sintering
temperature on density, dimensional change and microstructure of the Al alloy was studied.
Microstructural evaluation was accompanied by XRD and DSC methods in order to determine the
temperature and chemical composition of the liquid phases formed during sintering. It was found
that three transient liquid phases are formed at 420, 439 and 450 °C. Microstructural study revealed
the progressive formation of sintered contacts due to the presence of the liquid phases, although the
green compact expands as a result of the melt penetration along the grain boundaries. While Zn
melts at ~420 °C, the intermetallic phases between Al and Mg were found to be responsible for the
formation of liquid phase and the dimensional change at higher temperatures.
Acid-Insoluble Substances in Reduced Iron Powder from Ores
Authors: Wang Chong Lin , Zhang Chun Guang
Published: March 2009

X-ray analysis on iron ores and reduced iron powders revealed that around 60% acidinsoluble
substances were hexagonal and tetragonal quartz, another 40% substances were
sillimanite, alumina-silicate, an unnamed zeolite, all contained Si and Al. SEM images displayed
that the particle size of them was in the range of 3~7 μm, which may be the initial source of the
cracking in the sintered body. Statistics analysis showed that the Acid-Insoluble Content (AIC) for
high-grade magnetite powder was (0.130±0.010) % during the latest five months. The predicting
value for reduced iron powder from ore powders should be 0.179 %. However, the testing value for
reduced iron powder was (0.192±0.014) %. The limited difference of 0.013% might imply rare
pollution coming from the reduction and milling processes. The most important step for control
AIC should be the separation process of iron ore powders.
Consolidation of Bulk Metallic Glass Composites
Authors: Lee J.K. , Kim H.J. , Kim Taek Soo , Shin Seung Y. , Bae Jung Chan
Published: March 2009

Bulk metallic glass (BMG) composites combining a Cu54Ni6Zr22Ti18 matrix with brass
powders or Zr62Al8Ni13Cu17 metallic glass powders were fabricated by spark plasma sintering. The
brass powders and Zr-based metallic glass powders added for the enhancement of plasticity are well
distributed homogeneously in the Cu-based metallic glass matrix after consolidation. The matrix of
the BMG composite remains as a fully amorphous structure after spark plasma sintering. The BMG
composites show macroscopic plasticity after yielding, and the plastic strain increased to around 2%
without a decrease in strength for the composite material containing 20 vol% Zr-based amorphous
powders. The proper combination of strength and plasticity in the BMG composites was obtained
by introducing a second phase in the metallic glass matrix.
Application Experiences in Powder Compaction of Iron Powder - Influence of Tool Material on Tool Life
Authors: Sandberg Odd , Krona Andreas , Berg Sigurd , Kaad Flemming , Nord Göran
Published: March 2009

Tool steels for powder pressing are normally heat treated to a high hardness to counteract
plastic deformation during the compacting process. Ductility and wear resistance of the die punch
or core rod are determined by the type, size, amount, hardness and distribution of the hard phase in
the martensitic matrix. Thus, tool steels can be designed and optimized for specific powder pressing
application. To be able to utilize the full potential of the tool steel, also the design, heat treatment
and eventual surface coating of the steel must be taken into account. In this paper new low-friction
tool steel is investigated in PM manufacturing for a number of applications. An increase of tool life
of more than two times compared to ordinary tool steels is found. Furthermore, the new low friction
tool steel shows a potential for sintered parts with higher densities through the applicability of
increased compaction pressure or minimized lubricant amount.
Dimensional Precision in Sinter-Hardening PM Steels
Authors: Lindsley Bruce , Murphy Thomas
Published: March 2009

Dimensional precision is a critical parameter in net shape processing of ferrous PM
components. Beyond the dimensional changes associated with pressing and sintering of typical
low alloy PM steels, sinter-hardening alloys undergo a transformation from austenite to martensite.
The formation of martensite results in a large expansion during cooling, as martensite is the lowest
density phase in steels. Tempering hardened steels results in shrinkage, as the martensite converts
to a ferrite and carbide microstructure of higher density. Both of these transformations have a large
impact on the dimensional change. In addition, martensitic regions with high Cu and C contents
may contain large amounts of retained austenite. As austenite is the highest density phase, retained
austenite results in less growth of the compact. The presence of martensite and retained austenite,
in addition to the tempering step, all play a role in the final dimensions of a component. This paper
reviews two sinter-hardening grades and investigates the dimensional and microstructural changes
of those grades through different post-sintering thermal treatments.
Elaboration by Tape Casting and Hot Rolling of Copper/Silicon Carbide Composite Thin Films for Microelectronic Applications
Authors: Geffroy Pierre Marie , Silvain Jean François , Chartier Thierry
Published: March 2009

During the last decade, the use of metal matrix composites (MMCs) materials such as Al/SiC or CuW for microelectronic devices have made powder modules more reliable. Today, due to the continuous increasing complexity, miniaturization and high density of components in modern devices, high power microelectronic industries are looking for new adaptive thin films with high thermal conductivity, low coefficient thermal expansion, and good machinability. This paper presents an original and new elaboration method (tape casting and hot rolling) which has been optimized in order to elaborate copper/silicon carbide thin film composite materials. The first part presents the optimization of the tape casting parameters used (powder mixing; optimization of the nature and concentration of organic additives; tape casting, debinding and pre-sintering conditions). In the second part, the main characteristics of thin film obtained are discussed, such as thermomechanical properties of the composite Cu/SiC thin films.
Aerosol Synthesis and Growth Mechanism of Magnetic Iron Nanoparticles
Authors: Kim D. , Vasilieva E.S. , Nasibulin A.G. , Lee D.W. , Tolochko Oleg V. , Kim Byoung Kee
Published: March 2009

Magnetic oxide-coated iron nanoparticles with the mean size ranging from 6 to 75 nm
were synthesized by aerosol method using iron carbonyl as a precursor under the flowing inert gas
atmosphere. Oxide shells were formed by passivation of as-prepared iron particles. The influence of
experimental parameters on the nanoparticles’ microstructure, phase composition and growth
behavior as well as magnetic properties were investigated and discussed in this study.
Mechanical Properties of W-X (X=Cu, Ag or BAg-8) Composites
Authors: Hanado H. , Hiraoka Yutaka , Inoue Takeshi , Akiyoshi N.
Published: March 2009

Bend tests were performed at temperatures between 273 and 363 K for W-19vol%Cu, W-22vol%Ag and W-19vol%(BAg-8) composites. Yield and/or maximum strengths and ductility of the composite were discussed in terms of microstructure and fractography. Results are summarized as follows. (1) Almost no difference was recognized in yield strength between the composites. In contrast, a large difference was recognized in maximum strength and ductility between the composites. Maximum strength and ductility of W-Ag and W-(BAg-8) composites were generally much inferior to those of W-Cu composite. (2) Inferior mechanical properties of W-Ag composite to W-Cu composite are attributed to heterogeneous distribution of Ag-phases, whilst inferior mechanical properties of W-(BAg-8) composite to W-Cu composite are attributed to large pores at grain boundaries.
Microstructure Characterization of SiCp-Reinforced Aluminum Matrix Composites by Newly Developed Computer-Based Algorithms
Authors: Kretz Ferenc , Gácsi Zoltán , Gür C. Hakan
Published: March 2009

This paper presents a new approach for analyzing the microstructure of SiCp-reinforced aluminum matrix composites from digital images. Various samples of aluminum matrix composite were fabricated by hot pressing the powder mixtures with certain volume and size combinations of pure Al and SiC particles. Microstructures of the samples were analyzed by computer-based image processing methods. Since the conventional methods are not suitable for separating phases of such complex microstructures, some new algorithms have been developed for the improved recognition of the particles in the metal matrix composites. One of the most determining attribute of composites structure is anisotropy, but the measurement of this parameter is very difficult and slow. For this reason, the anisotropy of metal matrix composites was investigated by the newly developed algorithm which has an optimized speed.
Long-Term Strain Measuring of Technical Textiles by Photographic Method
Authors: Hegyi Dezső , Sajtos István , Sándor György
Published: March 2009

The technical textiles are very sensitive materials. To measure the elongation of such a
material needs special care. A photographic procedure has been investigated to measure the plain
elongation of textile specimens. It is especially suitable for long-term measuring programs. Some
experimental results measured by the described method are published.
On the Wettability, Encapsulation and Surface Phase Transition in Monotectic Liquid Metallic Systems
Authors: Kaptay György
Published: March 2009

In the present paper the wettability of a liquid metal by another liquid metal is studied theoretically,
based on a recent model on interfacial energies in metallic systems. It appears that in all practical
cases the liquid metal with a lower surface tension will perfectly wet (with a zero contact angle) the
liquid metal with a higher surface tension practically at any temperature, and therefore will
encapsulate it. As a result, the first order surface phase transition will start in monotectic metallic
systems at 0 K. The phenomenon of the surface phase transition is considered in some details, based
on a recent paper.
Influences of Manufacturing Technology on the Mechanical Properties of Silicone Rubber Structures
Authors: Keskeny József , Huba Antal
Published: March 2009

The paper presents the results of investigations made to clear how the different manufacturing technologies of silicone rubber structures affect the mechanical properties of the products. The problem is not obvious since there are numerous devices produced especially for the health care. We also controlled extreme high purity silicone rubbers and compared the results with data measured on simple industrial silicone rubbers. The aim was to see the difference between expensive medical materials and normal ones to simplify the fatigue tests and to decrease the costs of other mechanical investigations.
Hydroxamic Acid Corrosion Inhibitor for Steel in Aqueous Solution
Authors: Alagta Abdulmajed , Felhősi Ilona , Kálmán Erika
Published: March 2009

The selected dihydroxamic acid derivatives, namely oxalyl-dihydroxamic acid (C2) and pimeloyl-1,5-di-hydroxamic acid (C7) have been synthesized and evaluated as corrosion inhibitors for carbon steel in neutral aqueous solution by potentiodynamic polarization and ac impedance methods. C2 molecule acts as good inhibitor with inhibition efficiency value reached 91%; it is well adsorbed most likely throughout the two hydrophilic groups, and forms a protective film on the metal surface. C7 has moderate inhibition efficiency probably due to the presence of long single hydrocarbon chain in the molecule, negatively affect the adsorption process. Addition of Ni2+ to C7 significantly improve the inhibition efficiency, throughout the formation of a dense compact layer of complexes between Ni2+ and C7.
Zn-Al-Mg Coatings: Thermodynamic Analysis and Microstructure Related Properties
Authors: De Bruycker Evy , Zermout Zinedine , De Cooman Bruno C.
Published: March 2009

Demands for highly corrosion resistant coated steel are growing. As a result, Zn-Al-Mg coatings were developed. The possibilities of these coatings were investigated and the thermodynamics of the Zn-rich corner of the Zn-Al-Mg system were modelled. Different Zn-Al-Mgcoatings were produced and the microstructure was studied. Simulations of the solidification microstructures were carried out. The properties of the different coatings, like corrosion resistance and formability, were investigated. The thermodynamic model fairly accurately predicted the liquidus and transformation temperatures for low amounts of Al (≤4wt%) and Mg (≤3wt%). In the coatings the MgZn2 phase was present instead of the thermodynamically stable Mg2Zn11. The coatings with 3wt%Mg consisted of primary Al-fcc, MgZn2 crystals and ternary Zn-hcp/Alfcc/ MgZn2 eutectic. The addition of small amounts of Mg to a galvanizing bath caused a Znhcp/ MgZn2 eutectic to grow at the grain boundaries. Mg additions to a Zn+5wt%Al bath resulted in coarsening of the Zn-hcp/Al-fcc eutectic when added in small amounts and, when added in larger amounts (>0.2wt%Mg), a ternary Zn-hcp/Al-fcc/MgZn2 eutectic appeared. Cyclic corrosion tests and bending tests showed that the addition of Mg greatly enhanced the corrosion resistance, but decreased the cracking resistance of the coatings.
Suspension Plasma Spraying of Intermediate Temperature SOFC Components Using an Axial Injection DC Torch
Authors: Oberste Berghaus Jorg , Legoux Jean Gabriel , Moreau Christian , Hui Rob , Ghosh Dave
Published: March 2009

Intermediate temperature SOFC components, such as dense, nanostructured SDC electrolytes (samarium doped ceria) and porous anode sublayers were fabricated by suspension plasma spraying using an axial feed dc plasma torch. The liquid carrier employed in this approach allowed for controlled injection of much finer particles than in conventional thermal spraying, leading to thin coatings with a refined microstructure. Dense, thin (<10(m) and non-fractured electrolytes were created. Various processing routes for SOFC half-cells, using tape-cased, plasmasprayed and suspension-sprayed anodes, were explored. Loss of integrity and non-continuous coverage of the anode constituted the principal difficulties in the subsequent electrolyte deposition. The role of suspension feedstock particle size is discussed. Amongst various schemes investigated, a processing route that employs sequential suspension plasma spraying steps for both the electrolyte and the anode, using relatively large primary particles in the feedstock, constituted the most promising approach.
Effect of Initial Grain Size and Strain Path on Grain Refinement in Magnesium Alloy AZ31
Authors: Yang Xu Yue , Miura Hiromi , Sakai Taku
Published: March 2009

Grain refinement taking place in a magnesium alloy AZ31 was studied in a single- and
multi-directional compression at a temperature of 573K. The structural changes observed by
SEM/EBSD analysis can be characterized by the evolution of many mutually crossing kink bands
at low strains, continuous increase in their number and misorientation angle in moderate strain and
finally full formation of a fine-grained structure in high strain. The characteristics of new grain
evolution process are sensitively affected by initial grain size (D0) and strain path. New grains are
developed faster with decrease in D0. Multi-directional compression accelerates the evolution of
fine grains and the improvement of plastic workability. The mechanism of new grain formation is
discussed in detail.
Development of Metal Foam for Application of Automotive Part
Authors: Hur Bo Young , Kim Sang Youl , Um Yong Su , Ryu Yong Mun
Published: March 2009

A study on the tensile, compression and bending test of Aluminum foam Application for
auto bumper and rod. We know a more efficiency to adhesive Aluminum foam out side of part in
aspect to price, weight and capacity when make auto-component using aluminum foam. We secured
basis properties of aluminum foam for applying auto-component by tensile, compressive and
bending test. Aluminum foam was equipped to crash core with different shape. The results of
maximum loads test are higher by full> cavity> bridge> half type relationship order. And, we could
know that a difference of weight of full, cavity, and bridge type is not big.
High Performance Soft Magnetic Composite (SMC) Produced by Improved Process
Authors: Morimoto Koichiro , Nakayama Ryoji
Published: March 2009

Soft magnetic composites (SMC’s) are produced compacting iron powder coated with a thin insulator and then heat-treating the greens. In this study, to improve magnetic properties of SMC’s, formation of heat resistant MgO insulation layer on iron powder particles was examined. It was found that the MgO coating can be made by a dry process with two steps, i.e., oxidation of the iron particle surfaces and reduction of iron oxide by magnesium vapor. The SMC fabricated from the MgO-coated powder exhibits high resistivity even after heat treatment at 600, which leads to low iron losses comparable to those of the as-punched silicon-iron laminations. This can be ascribed to complete relief of stress introduced in the compaction process.
Strength of AZ31 Alloys Subject to Severe Deformation by ECAP and DSR
Authors: Kim Woo Jin , Jeong Ha Guk
Published: March 2009

By controlling texture and grain refinement using ECAP (equal channel angular pressing)
process that induces severe shear deformation on materials without change their diameter, strength
and ductility of the AZ31 alloy in the bulk form of rod could be enhanced. The original texture was
completely replaced by a new texture rotated to have a high Schmid factor during ECAP. The
decrease of yield stress after ECAP despite achievement of significant grain refinement was
attributed to the strong effect of texture modification. The effect of differential speed rolling (DSR)
on mechanical properties of the AZ31 alloy in the form of sheet was examined. Significant grain
refinement took place during the rolling owing to introduction of large shear deformation by
application of high speed ratio between the upper and lower rolls. Hall-Petch relations of the
ECAPed and DSRed AZ31 alloys were compared and notable difference in strength between the
two alloys at a given grain size was found and it was attributed to strong texture effect on strength
of Mg alloys.
Effects of High Gradient Magnetic Fields on Solidified Structures of Non-Magnetic Metals with Different Susceptibilities
Authors: Wang Qiang , Wang Chun Jiang , Zhang Hai Tao , Wang En Gang , He Ji Cheng
Published: March 2009

In the present study, the influencing factors such as the intensity and the direction of
gradient magnetic fields, the magnetic susceptibilities of non-magnetic metals on the structures are
studied theoretically and experimentally. In the theoretical analyses, the influences of high gradient
magnetic fields on nucleation and structures are investigated. In the experimental research, high
gradient magnetic fields are imposed on paramagnetic material Al and diamagnetic one Sn during
their solidification processes. Then the macro- and microstructures of these samples are examined
and the influences of magnetic susceptibilities of metals, the intensity and the direction of high
magnetic fields are analyzed in details. It is found that solidified structures could be refined when the
magnetization force and gravity were in the same directions, while the solidified structures could be
coarsened and the coarse dendrites grew along the direction of the imposed magnetic fields when the
directions of these two forces were opposite. Those phenomena could be explained from the views of
reduced gravity and elevated gravity effects caused by magnetization force and the convection
suppression effect caused by high magnetic fields. The results indicate that high magnetic fields can
be applied to control the solidified structures of metals and then improve the quality and the
properties of materials for different purposes.
Automotive Mg Research and Development in North America
Authors: Carpenter Joseph A. , Jackman Jennifer , Li Nai Yi , Osborne Richard J. , Powell Bob R. , Sklad Philip S.
Published: March 2009

Expanding world economic prosperity and probable peaking of conventional petroleum
production in the coming decades requires efforts to increase the efficiency of, and the development
of alternatives to, petroleum-based fuels used in automotive transportation. North America has been
aggressively pursuing both approaches for over ten years. Mainly as a result of lower prices due to
global sourcing, magnesium has recently emerged as a serious candidate for lightweighting, and thus
increasing the fuel efficiency of, automotive transportation. Automotive vehicles produced in North
America currently use more Mg than vehicles produced elsewhere in the world, but the amounts per
vehicle are very small in comparison to other materials such as steel, aluminum and plastics. The
reasons, besides price, are primarily a less-developed state of technology for Mg in automotive
transportation applications and lack of familiarity by the vehicle manufacturers with the material.
This paper reviews some publicly-known, recent, present and future North American research and
development activities in Mg for automotive applications.
Structural Characterization and Corrosion Properties of BTESPT Silane Films on Surface of 2024-T6 Aluminium Alloy
Authors: Chen Ming An , Xie Xuan , Xu Guo Fu , Li Hui Zhong , Zhang Xin Ming
Published: March 2009

2024-T6 Al alloy sheet s were modified by bis-[triethoxysilylpropyl] tetrasulfide
(BTESPT) silane film to improve the corrosion resistance. Fourier-Transform Reflection Absorption
(FTIR-RA) spectroscopy was used for structural characterization of BTESPT silane film formed on
surface of the sheet. Potentiodynamic polarization and immersion test in 3.5% NaCl solution were
used for evaluating the corrosion performances of the silane film. The results showed that the film
formed after curing at 120 °C for 40 min was cross-linked through Si-O-Si and that it was covered on
the entire surface of the sheet. The content of elements S and Si on the Al2CuMg particles is a little
higher that of on the matrix. The strong peak at 1032 cm-1 indicated that the film was linked to the
sheet by Si-O-Al. Compared to the untreated case, the corrosion current density of the sheet treated
with the silane film was reduced by close to 2 orders. Treatment of BTESPT silane can provide about
670 h protection of corrosion for the sheet in 3.5% NaCl water solution.
A Novel Squeeze Casting Process for Producing Magnesium Wheels
Authors: Xu Shao Yong , Long Si Yuan , Li Fen Ge
Published: March 2009

This paper analyzes the casting process characteristics of Mg alloys compared with Al
alloys in the production of high quality (i.e. structural) structural vehicle components. The
disadvantages of traditional squeeze casting for high quality Mg components has led the authors to
develop a novel squeeze casting process which overcomes the drawbacks of the current methods. The
details of the new process are presented here and show the increased productivity and quality of
castings that can result from changing the way molten metal is handled and processed. The feasibility
of this new squeeze casting process was applied to Mg wheels for LX150 motorbikes.
Anti-Oxidation and Anti-Corrosion Properties of Al-Si Metal Anodes
Authors: Cao Xiao Zhou , Qiu Zhu Xian , Shi Zhong Ning , Hu Xian Wei , Ban Yun Gang , Wang Zhao Wen
Published: March 2009

Al-Si metal anode was fabricated by cold-press sintering with Al and Si as embedded
powder in argon atmosphere. The anti-oxidation in the air and anti-corrosion in molten cryolite
properties of Al-Si metal anode at high temperature were examined. The experimental results showed
that the oxidation kinetics curve obeyed the parabolic law. The corrosion behavior Al-Si metal anode
was studied in electrolysis test. The electrolyte consisted of Na3AlF6(90 wt%),CaF2(5 wt%) and
Al2O3(5 wt%) which corresponded to molecular ratio of 2.4. The results indicated that the cell voltage
was stable and the electric polarized corrosion rate was higher than the static corrosion rate of metal
anode. SEM photographs showed an oxidation film formed in the surface of Al-Si metal anode which
can obstruct the further corrosion in molten cryolite. It may be concluded that Al-Si metal anode has
good combination property and can replace the carbon anode in the aluminum cell.
Effects of Ru Additions on the Microstructures and Stress Rupture Life of a Directionally Solidified Ni-Based Cast Superalloy
Authors: Han Xiao Lei , Han Ya Fang , Li Shu Suo , Ma Wen You
Published: March 2009

Two directionally solidified (DS) Ni-based cast superalloys without and with 3wt. % Ru were prepared. The effects of Ru addition on the microstructures and stress rupture properties of the heat treated superalloys were investigated. It is shown that the amount of eutectic in 3wt. % Ru alloy was less than that in alloy without Ru. The incipient melting structure was found after quenching followed by 1295°C and 1300°C solid solution treatments in 3wt. % Ru alloy and in the alloy without Ru, respectively. The temperature at which the eutectic pools dissolved completely was higher than the temperature at which incipient melting appears. In order to obtain the better mechanical properties, double aging treatment was carried out for both alloys to optimize the sizes, morphologies and distribution of the γ′ phase. The stress rupture lives of the alloys were 55h and 108h under the condition of 1070°C and 137MPa the alloys without Ru and with 3wt. % Ru respectively. It is suggested that 3wt. % Ru addition can prolong the stress rupture life of the alloy.
Influence of Aging Temperature on the Microstructure and Stress Rupture Property of DZ951 Alloy
Authors: Xia P.C. , Yu Jin Jiang , Sun Xiao Feng , Guan Heng Rong , Hu Zhuang Qi
Published: March 2009

Effect of different aging temperatures on microstructure and stress rupture properties of
DZ951 alloy were investigated in this paper. The results show that the shape of carbide changed from
script-like in as-cast alloy to block during different aging treatments. MC carbide degrades into M23C6
at the aging temperature of 970°C, which made alloy have a better combination of strength and
ductility than that at other aging temperatures. The size of γ′ phase increases and the shape of γ′ phase
changed from sphere (870°C) to quasi-cuboid (920°C) and cuboid (970°C) with the increasing aging
temperature. The stress rupture life of DZ951 alloy at 1100°C/60MPa improves with the increased of
aging temperature. The fractographs at different conditions showed a ductile fracture mode.
Isothermal Oxidation Behavior of Ni Base Superalloy DM02 for High Temperature Dies
Authors: Li Qing , Song Jin Xia , Xiao Cheng Bo , Qu Shi Yu , Wang Ding Gang , Han Ya Fang
Published: March 2009

The isothermal oxidation behavior of a new developed Ni base superalloy named DM02
for high temperature dies was studied in this paper. The dynamic curve was achieved by monitoring
weight gain of the alloy as a function of time. The results showed that the alloy had fairly good
oxidation resistance at 1050°C and 1100°C. The oxidation kinetics at both 1050°C and 1100°C
followed parabolic rules in segment. It has been found that the oxidation of the alloy was controlled
by multi-oxides of (Ni, Co)O, (Ni, Co)Al2O4, and NiWO4, growth mechanism in the primary stage,
and by Al2O3, NiAl2O4 growth mechanism in the following stage. After oxidation at 1050°C for 100h,
the oxide scale of the alloy was mainly composed of two areas. Some were thin uniform (Ni，
Co)Al2O4(outer)/Al2O3 (inner) composites scale and others were multi-layer oxide scale of ( Ni,Co)O
/ multi-oxides (mainly NiWO4、NiO and NiAl2O4.) /Al2O3.
Degeneration of Primary MC Carbide in a Cast Ni-Base Superalloy
Authors: Qin X.Z. , Guo Jian Ting , Yuan C. , Hou Jie Shan , Ye Heng Qiang
Published: March 2009

During long-term thermal exposure, the degeneration of primary MC carbide is a
diffusion-controlled process. With the element exchange between the primary MC carbide and the γ
matrix, three MC degeneration reactions, that is, γ + MC → γ' + M23C6 (Reaction I), MC + γ →η+
M23C6 (Reaction II) and MC + γ →η+ M6C (Reaction III), sequentially operates. Of them Reaction III
has never been reported in the previous references and is kinetically most difficulty. It is also shown
that the grain boundary MC decomposes much more rapidly than the grain interior MC and that
Reaction III is not as often seen at the grain boundary as in the grain interior.
Density of Ni-Co-Al Ternary Alloys in Liquid States Measured by a Modified Pycnometric Method
Authors: Fang Liang , Xiao F. , Zhang S.F. , Yang L.C. , Yang L.C. , Tao Z.N.
Published: March 2009

The density of Ni-Co-Al ternary alloys with a relative fixed mole ratio of
Ni/Co(xNi:xCo≈86:14) and aluminum concentration change from 0 to 10% mass fraction in liquid
states were measured by a modified pycnometric method(MPM). It was found that the density of the
liquid Ni-Co-Al alloy decreases with increasing temperature, Al concentration and the ratio of Al
concentration to Ni concentration in the alloy. The temperature coefficient of density changes with
increasing the Al concentration or the ratio of Al concentration to Ni concentration in the ternary
alloys. The measured densities by MPM were comparable with that by the modified sessile drop
method, the maximum difference of density between them was about ±0.56%. The molar volume of
liquid Ni-Co-Al alloy increases with increasing temperature and changed with increasing Al
concentration. And the partial molar volume of aluminum in Ni-Co-Al alloy was calculated
approximately. The molar volume of liquid Ni-Co-Al ternary alloy determined in the present work
shows a negative deviation from the ideal linear molar volume.
Mechanical Property and Elastic Modulus of Metastable Ti-Nb Based Alloys with Si Addition
Authors: Kim Han Sol , Kim Won Yong
Published: March 2009

Mechanical Property and elastic modulus of Ti-Nb based alloys with various Si content,
prepared by water quenching from high temperature β phase field, cold rolling and recrystallization
heat treatment followed by water quenching, were investigated in terms of tensile test and resonance
vibration method. TEM observations revealed that in addition to orthorhombic structured α" phase
and bcc structured β phase, an intermediate ω phase is characterized in the microstructure. The
volume fraction ratio of constituent phases was dependent upon Nb and Si contents. In as-quenched
samples yield strength increased with increasing Si content. This propensity was similar to the cold
rolled alloys. In recrystallized samples however, yield strength decreased slightly with increasing Si
content even though the alloy containing higher Si content showed smaller grain size. From these
results, it is found that strength of the present alloy influences largely on solid solution hardening and
phase stability but does weakly on grain size. Yield strength of cold rolled sample was higher than
as-quenched and recrystallized samples. Elastic modulus values were measured to 55GPa, 63GPa and
44GPa for as-quenched, cold rolled and recrystallized samples, respectively. The variations of yield
strength and elastic modulus values were interpreted in terms of changes in microstructure as well as
grain size and phase stability.
Microstructure Evolution of Ti-Al Peritectic System during the Initiated Stage of Directional Solidification
Authors: Su Yan Qing , Liu Chang , Li Xin Zhong , Guo Jing Jie , Fu Heng Zhi
Published: March 2009

The microstructure evolution of Ti-Al peretectic system in transient stage and steady state
in directional solidification was predicted via theoretical analysis. The solute distribution controlled
by diffusion at and ahead the solid-liquid interface will determine whether the properitectic and
peritectic phases can nucleate and grow ahead of the opposing solid phase. The formation of banding
structure is possible in a certain composition range. At the steady state, a microstructure selection map
was set up based on interface response function model. The microstructure of TiAl alloys with
different aluminum content was studied with Bridgman directional solidification method. Some
evidence in the experiment has been found to support the theoretical prediction.
Study of Hot Deformation Characteristics of an As-Cast Ti-22Al-25Nb Alloy
Authors: Liang Xiao Bo , Li Shi Qiong , Zhang Jian Wei , Cheng Yun Jun
Published: March 2009

The hot deformation characteristics of an as-cast Ti-22Al-25Nb alloy has been studied in
the temperature range of 1323-1523K and the strain rate range of 0.001-10s-1, using hot compression
tests. The experimental results indicated that discontinuous yielding occurs during the hot
deformation performed at the strain rate of 10s-1, while the flow curves are of a steady-state type at
lower strain rate range. Activation energy was obtained by analyzing the steady-state flow stress with
a standard constitutive equation. They are 260-282kJ/mol in the temperature range of 1473-1523K,
and 145-155kJ/mol in 1323-1423K. The processing map developed using the principles of dynamic
material modeling exhibits three domains for the present alloy: 1) a domain of dynamic
recrystallization of B2 phase in the temperature range of 1373-1423K at the strain rate range of
0.01-0.001s-1, with the power dissipation efficiency of about 35-50%, 2) a domain of dynamic
recovery of B2 phase in the temperature range of 1473-1523K at the strain rate less than 0.01s-1, with
the power dissipation efficiency of about 20-30%, 3) a domain of flow instability in the form of
adiabatic shear band in the temperature range of 1323-1373K at the strain rate larger than 1s-1.
Effects of Nb on the High Temperature Mechanical Properties of TiNiAl Alloys
Authors: Qiu Gao Song , Zhao Xin Qing , Meng Ling Jie , Xu Hui Bin
Published: March 2009

A series of NiTiAl based alloys with different amount of Nb addition were prepared and the
effects of Nb on both the mechanical properties and microstructure evolution were investigated. The
addition of Nb can remarkably enhance the high temperature yield strength of these alloys. The
highest yield strength of the alloys with 10 at% Nb reaches 1237MPa at 873K and 875MPa at 973K,
respectively. The Ti2Ni(Al,Nb) precipitates and the solution strengthening effect might be responsible
for the high yield stress achieved at high temperature.
Effect of B on the Microstructures and High Temperature Oxidation Resistance of a Nb-Si System In Situ Composite
Authors: Liu Ai Qin , Li Shu Suo , Sun Lu , Han Ya Fang
Published: March 2009

Nb-16Si-24Ti-6Cr-6Al-2Hf-xB(x=0, 0.5, 1, 2, 4, 6) in situ composites were prepared by
arc-melting. Microstructure and the effect of boron on 1250C oxidation resistance of the composites
were investigated by scanning electron microscopy(SEM) and X-ray energy disperse spectrum(EDS)
as well as X-ray diffraction(XRD). The experimental results showed that the high temperature
oxidation resistance of the alloy was remarkably improved by adding proper amount of boron. This
may be resulted from several beneficial roles of boron, i.e., boron improves the resistance of Nb5Si3
by solid solution strengthening, inhibits the diffusion of oxygen in the matrix, improves the adherence
between the oxide scale and the substrate and increases the cracking resistance of the oxide scale.
Effect of Silica on the Electrical Properties of Epoxy of Phenolic Resin/Carbon Black/Silica Composite Coating
Authors: Zhang Wei , Blackburn Richard , Dehghani Abbas
Published: March 2009

Nanocomposites were prepared by embedding carbon black and silica into phenolic resin
matrix, which was supported by SEM and particle size analyses. After milling stage, the obtained
hybrids were applied to transparency film using K control coater. By the crosslinking procedure,
homogenous surface coatings can be achievable. The electrical properties of surface coating can be
tailored by variation of silica content with the amount of carbon black fixed. The conductivity of the
surface coating increases steeply and then reaches a plateau with the increase of silica. When the
weight ratio of silica to carbon black is around 1:2, relatively high conductivity can be desirable.
Further increase in silica results in the decrease in conductivity. This can be interpreted in terms of
aided or blocked dispersion effects on carbon black imposed by silica. Also, the uniformity of the film
is verified by Si-mapping analysis.
Use of WEDM in the Characterization Process of Al/2-Phase Systems Consolidated by Multilayer Cylindrical Dynamic Compaction Method
Authors: Alba-Baena Noé G. , Murr Lawrence E. , Loya-Puga Alejandro , Salas Wayne
Published: March 2009

The aim of this paper is to present an exploratory process to characterize fabricated 2-phase
aluminum metal-matrix systems (2-phase systems) by using a dynamic consolidation technique, with
an arrangement of multilayer mixings in steel cylinders. Aluminum powder (~150mm) was
mechanically mixed with different fractions of multi-wall carbon nano-tubes (MWCNTs, 2 and 5
percent), with ~30 nm and ~30 μm diameter SiC and Al
2
O
3
powders (in volume fractions of 2, 4, and
21 percent), then, were green compacted uniaxially to ~80 % density, to be finally explosively
consolidated with ammonium nitrate-fuel oil (ANFO) and C3. After compaction, WEDM (wire
electrical discharge machining) was used to prepare tensile and hardness testing samples, also TEM,
light microscopy and SEM characterization samples, all by using ~25 % of the obtained material , this
represents less than 10cc , preserving ~60 % of the obtained monoliths. Densities of the consolidated
monoliths achieve an average of ~98 % compaction (measured by Archimedes technique).
Observations and measured hardness (HRE) reveal well compacted systems with a hardness
consistent along the composites. Using light microscope imaging different zones were identified
showing different grain behaviors.
Optimum Design, Microstructure and Mechanical Properties of Ti/Ti3Al Multi-Layered Materials
Authors: Ma Li , He Xiao Dong , Hu Zhao Hui , Sun Yue
Published: March 2009

This study concerned with the optimum design, microstructure and mechanical properties
analysis of a multi-layered metal/intermetallic materials consisting of Ti and Ti3Al prepared by the
electron beam physical vapor deposition (EB-PVD) technology. Based on fracture mechanics and
numerical simulation method, the optimized microstructure of Ti-Ti3Al multi-layered materials has
been obtained by analyzing the relation curve between structural parameters and work of fracture of
materials, then dual-target evaporating method was used to evaporate Ti and Ti-47Al bar alternately
to form Ti/Ti3Al thin sheet about 0.12mm thickness. Pattern and phase analysis by SEM and XRD
showed that there was homogeneous and continuous interface between layers and the intermetallic
layers were made up of α2 phase alloy. The tensile curve of Ti/Ti3Al microlaminates represented the
characteristic of multi-layered materials and the maximal extensibility of sample as deposited
reached 5.83% and the fracture appearance showed ductile rupture feature.
A Finite Element Model and Experimental Verification for the Mechanical Properties of 2.5-D Braided Composites
Authors: Dong Wei Feng , Li Yong , Xiao Jun
Published: March 2009

As for 2.5-D layer-to-layer angle interlock braided composites, the cross section of the
warp tow was represented in double-convex lens form, and the center line of the warp tow was
along the sinusoid. The arranging characteristic of weft tow fibers along the cross section outline of
the longitude fibers was studied in detail. A novel finite element model for 2.5-D braided
composites was established to predict elastic modulus. The finite element software ANSYS was
adopted to study the mechanical properties of the model and presented its stress nephogram, and the
influence of the braided structure parameters on the elastic modulus of this material was analyzed in
detail. To validate this model, qualified experimental samples were made by VARTM technique,
and then tensile tests were performed to determine the mechanical properties. The results show that
the conclusions of finite element method (FEM) fit well with the experimental values, and this
model can be used to predict effectively the macro modulus of 2.5-D braided composites.
Reaction Mechanisms of Combustion Synthesis of Si3N4 -SiC -TiN Ceramics
Authors: Zhang Xue Jun , Zheng Yong Ting , Han Jie Cai , Yang Xin Hong
Published: March 2009

DSC/TG analysis was used to investigate the change of TiSi2-SiC-N2 system in the
temperature range from room temperature to 1400°C. The relationships between $G and T about the
reactions possible occurring in TiSi2-N2 system during combustion synthesis were calculated. In order
to study the combustion process in detail, the reaction of TiSi2-SiC-N2 system was stopped at
different stages by quenching the samples. The composition and microstructure in different reaction
zones were analyzed by means of XRD and SEM, accordingly, reaction kinetic model of
TiSi2-SiC-N2 combustion system was established. The result showed that TiSi2 firstly reacted with N2
to form TiN and Si, and subsequently Si were nitrified.
Kinetics of Interfacial Reaction in SiCf/Ti6Al4V Composites
Authors: Yang Yan Qing , Lu X.H. , Luo X. , Ma Z.J. , Li J.K. , Wen Q. , Chen Y.
Published: March 2009

The Ti6Al4V composites reinforced with Chinese SiC fiber was manufactured and then
thermally exposed at 800°C, 900°C and 1000°C, respectively, for up to 500h. The interfacial reaction
products were identified as TiC between Ti6Al4V and the C-coating of the SiC fiber. However, if the
SiC fiber has no C-coating, the interfacial reaction forms TiC, Ti3SiC2, Ti5Si3(Cx) and Ti3Si(Cx). The
thickness of the interfacial reaction zone was measured and it is found that the thickening rate is
slower in the samples in which the SiC fiber has the C-coating. The growth of the interfacial reaction
products is diffusion-controlled and the parameters of the growth kinetics, k0 and Q, were determined,
respectively. The profile of the element distribution was calculated according to the diffusion theory
and is well consistent with the expeimental data.
Structural Optimization Design of MR Fluid Clutch
Authors: Meng Wei Jia , Huang Zhan Wen , Liu Yan Ju , Wu Xiao Rong , Sun Yi
Published: March 2009

Magnetorheological (MR) fluids are suspensions of micron sized ferromagnetic particles
dispersed in varying proportions of a variety of non-ferromagnetic fluids. MR fluids exhibit rapid,
reversible and significant changes in their rheological (mechanical) properties while subjected to an
external magnetic field. In this paper, a double-plate magneto-rheological fluid (MRF) clutch with
controllable torque output have been designed. Electromagnetic finite element analysis is used to
optimize the design of the clutch by using the commercial FEA software ANSYS.
A Comparison of the Mechanical Properties of RF- and DC- Sputter-Deposited Cr Thin Films
Authors: Park Min Woo , Lee Wang Woo , Lee Jae Gab , Lee Chong Mu
Published: March 2009

Chromium (Cr) films were deposited on plain carbon steel sheets by DC and RF magnetron sputtering as well as by electroplating. Effects of DC or RF sputtering power on the deposition rate and properties such as hardness and surface roughness of the Cr films were investigated. X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microcopy (SEM) analyses were performed to investigate the crystal structure, surface roughness, thickness of the Cr films. The deposition rate, hardness and surface roughness of the Cr film deposited by either DC or RF sputtering increase with the increase of sputtering power. The deposition rate and hardness of the Cr film deposited by DC sputtering are higher than those of the Cr film deposited by RF sputtering, but RF sputtering offers smoother surface. The sputter-deposited Cr film is harder and has a smoother surface than the electroplated one.
Thermal Cycling and Hot-Corrosion Behavior of Plasma Sprayed Segmented Thermal Barrier Coatings
Authors: Guo Hong Bo , Murakami Hideyuki , Kuroda Seiji
Published: March 2009

Modified zirconia thermal barrier coatings (TBCs) with segmentation cracks were sprayed
onto a TMS 82+ single crystalline substrate. The thermal cycling lifetime of the modified TBC was
improved by 10 times compared to that of the traditional non-segmented TBC. Also, the modified
coating showed much better resistance to high temperature cyclic hot-corrosion.