bluuebunny/crossref_metadata_2025 huggingface dataset:
A 21st. Century Perspective on Molybdenum Powder Production by Hydrogen Reduction
Authors: Martins G.P. , Kangsadan Tawiwan , Scott Grant , Wagner Christopher , Van Hoose Jeff
Published: March 2009

High purity molybdenum metal powder is produced commercially from hexavalent molybdenum
precursors, viz.: ammonium dimolybdate (ADM) or molybdenum trioxide. One conventional
process incorporates first-stage and second-stage flowsheet components, with hydrogen gas serving
as reductant. This two-stage strategy is employed in order to minimize the formation of volatile
molybdenum species that would otherwise be generated at the high temperature required to obtain
molybdenum (Mo) in a single stage conversion of the molybdenum precursor. Although
molybdenum powder has been produced commercially for over a century, a comprehensive
understanding of the kinetic mechanisms and powder characteristics, e.g. oxygen content and
particle morphology, is far from being definitive. In fact, it might be argued that the “art” and
engineering, in a commercial context, has advanced ahead of the fine-detail science-derived
metallurgical process-engineering. Theoretical contributions presented in this paper are focused
primarily on the fundamentals of the conversion process associated with second-stage reduction
process – MoO2 to Mo and the factors that contribute to the oxygen content of the molybdenum
powder product (1000 to 100 ppm(w) O, range). Thus, equilibrium-configuration details
concerning both solid and gas phases are addressed, including the volatile hexavalent molybdenum
vapor complexes as well as solubility of oxygen in molybdenum. In regard to the role of a chemical
vapor-transport mechanism on powder morphology in second-stage conversion of MoO2 to Mo, it is
shown that the partial pressure of the prominent molybdenum hydroxide vapor-complex
(MoO2(OH)2) is far too low to support such a mechanism. This contention has been corroborated by
employing helium to control the partial pressures of hydrogen and water in the gas phase.
Secondarily, a limited assessment of the intrinsic rate-controlling mechanisms that can contribute to
the residual oxygen-content of the Mo powder product is also provided. Powder morphology, and
its concomitant influence on specific surface-area of the Mo powder product, is found to correlate
with the oxygen-content determination of the powder produced during second-stage reduction, and
according to the processing strategy employed. Consequently, it has been found cogent to
“partition” second-stage reduction into: i) a relatively high-rate Primary Reduction Sequence, and ii)
a lower rate Deoxidation Sequence.
Phase Equilibria and Atomic Diffusion in the Ir/CoAl System
Authors: Kimura Yoshisato , Ohsaki Mototsugu , Fujita Hiroki , Mishima Yoshinao
Published: March 2009

Aiming for the design of simple thermal coatings including Ir as a diffusion barrier layer
with B2 aluminides bond coat such as CoAl, diffusion behavior and phase equilibria at the Ir/CoAl
interface have been investigated to understand thermal and chemical stability of the interface.
Diffusion couples were prepared with various conditions of Ir, plate, powder and film deposited to
examine the effects on diffusion behavior. Moreover, the interdiffusion coefficient of binary Ir-M in
the Ir solid solution, DIr-M was determined using Boltzmann-Matano method, where M is selected
form elements used in heat resistant alloys. The potential of Ir as a diffusion barrier has been
evaluated particularly against diffusion of Al.
Hydrothermal Synthesis of Bi1.5ZnNb1.5O7 Nanopowders
Authors: Huang Jin Liang , Wang Xiao , Yang Liu Shuan , Cui Chun Wei , Yang Xing Hua
Published: March 2009

The cubic pyrochlore phase Bi1.5ZnNb1.5O7 nanopowder was successfully synthesized by
the hydrothermal method (HTM) from the starting materials: Bi(NO3)3·5H2O, ZnO, Nb2O5 and the
mineralizer: KOH. The XRD patterns prove that the cubic pyrochlore phase Bi1.5ZnNb1.5O7
nanopowder can be obtained by HTM, and TEM photographs show that the powders present the
regularly granular shape, when the hydrothermal reactions were conducted at synthesis temperatures
140~220°C and reaction time for 6~48h. The crystalline sizes of the powders were calculated by the
Scherrer equation to be about 43~49nm. The crystalline sizes decreased both with the increase in
synthesis temperature and the prolonged reaction time until they reached to the minimum size about
43nm at 220°C for 24h.However, they tended to increase when the reaction time was above 24h.
Millimeter-Wave Assisted Sintering of Polycrystalline Yttria for Laser Host Material
Authors: Hornstein Melissa K. , Bruce Ralph W. , Fliflet Arne W. , Gold Steven H. , Kahn Manfred , Imam M. Ashraf
Published: March 2009

We report an investigation of millimeter-wave processing of yttria for fabrication of
transparent, high-strength polycrystalline laser hosts for high energy laser (HEL) applications.
Advantages of polycrystalline, compared to single-crystal laser host materials, include lower
processing temperature, higher gain with flexibility of higher dopant concentrations, cheaper
fabrication, and larger-size devices. Millimeter-wave processing is an alternative method to solve
the problems of both conventional vacuum and low-frequency microwave sintering, such as low
heating rate, poor coupling and thermal gradients. A major component of the millimeter-wave
processing facility is a 20-kW, continuous-wave, 83-GHz gyrotron oscillator. Yttria has been
successfully sintered with millimeter-wave beams with up to 99% theoretical density. A partially
transparent yttria sample has also been achieved using the millimeter-wave sintering process [1].
Several factors impact the quality of the sintered material including the presence of agglomerates,
impurities, processing atmosphere, sintering aids, and thermal gradients. Efforts to improve the
transparency will be discussed.
Barium Titanate Nanopowders Prepared from the Modified Oxalate Co-Precipitation Method
Authors: Pookmanee Pusit , Khantha Chanitpa , Phanichphant Sukon
Published: March 2009

Barium titanate nanopowders were prepared from the modified oxalate co-precipitation
method. Barium chloride dihydrate and potassium titanyl oxalate dihydrate were used as the starting
precursors with the mole ratio of Ba:Ti as 1:1. Barium titanyl oxalate complex powders were
obtained after adjusting the final of pH of the solution to 1. The precipitates were filtered, washed
and dried at 100 oC for 5h. The precipitate powders were calcined at 400-700 oC for 2h. The phase
transition was studied by X-ray diffractometry (XRD). Cubic structure of barium titanate was
obtained after calcinations at 700 oC for 2h. The morphology and chemical composition were
investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy
(EDXS). The range of particle size was 50-100 nm with irregular in shape. The elemental
composition of barium, titanium and oxygen showed the characteristic X-ray energy values.
Synthesis of Ultra-Fine and High-Pure Zirconium Diboride Powders Using Solution-Based Processing
Authors: Wang Chang An , Wang Hai Long , Yu Lei , Huang Yong
Published: March 2009

Ultra-fine and high-pure zirconium diboride powders were prepared by carbothermal
reduction boronization of zirconia/boron carbide/carbon mixtures. Fine-scale mixing of the reactants
was achieved by solution-based processing in which zirconium oxychloride (ZrOCl2⋅8H2O) as the
zirconia-bearing precursor was precipitated in the suspension of boron carbide (B4C) and carbon
powders in water. The carbothermal reduction boronization reaction was substantially completed at
relatively low temperatures (<1600°C) and the resulting products (ZrB2 powders) had small average
grain sizes (1~2 μm) and high purity (>99.6 wt%). The experiments indicated that excessive B4C and
C were necessary during the carbothermal reduction boronization because of volatilization of boron
and carbon elements. The effects of temperature and holding time on the synthesis of ZrB2 powders
were also discussed.
Simultaneous Synthesis and Consolidation of W-Added ZrB2 by Pulsed Electric Current Pressure Sintering and their Mechanical Properties
Authors: Ken Hirota , Endo Takaya , Masaki Kato , Nakane Shingo , Nishimura Toshiyuki , Morisada Yoshiaki , Mizuuchi Kiyoshi
Published: March 2009

Dense zirconium boride (ZrB2)-based materials with and without tungsten (W) have been
fabricated directly from mixtures of constituent elemental powders by pulsed electric current
pressure sintering (PECPS) at 1800°C for 10 min under 30 MPa in a vacuum. Formation processes
of monolithic, W-doped ZrB2 solid solutions (Zr1-xWx)B2 (0<x≤0.12), and composites consisting of
ZrB2(ss) and WB2 were investigated. Their mechanical properties of Vickers hardness (Hv), fracture
toughness (KIC), and bending strength (σb) at room temperature were evaluated. Solid solution and
composite materials gave higher Hv (~20.7 GPa), KIC (∼4.4 MPam1/2), and σb (~600 and 690 MPa
for the former and the latter, respectively) than those (14.1 GPa, 3.21 MPam1/2, and ~500 MPa) of
the monolithic ZrB2 fabricated under the same conditions. Furthermore, the latter two materials
exhibited excellent high-temperature σb values (~550-600 MPa) up to 1600°C in N2, in comparison
with that (~320 MPa) of monolithic ZrB2 materials.
Microstructural Features of a Ultra Low Carbon High Strength Acicular Ferrite Steel Thick Plate
Authors: Cao Zhi Qiang , Zhang Ai Bing , Luo Deng , Xia Zheng Hai , Zhang Yong Dong , Wu Kai Ming
Published: March 2009

A ultra low carbon high strength steel heavy plate (60∼80mm thick) was produced with
TMCP at Xiangtan Steel. The steel has a good combination of high strength (σb∼600MPa) and impact
toughness (∼300J). The microstructural features were analyzed by optical microscopy and scanning
electron microscopy (SEM). Results showed that microstructures consisted of a large amount of
acicular ferrite and a small amount of polygonal ferrite. A very few amount of retained austenite was
also observed in the microstructures. The formation of fine acicular ferrite resulted in the high
strength of the steel plate. The good impact toughness of the steel plate is mainly attributed to the
formation of acicular ferrite and a very few amount of retained austenite.
Zinc Oxide Ceramics with High Mobility as n-Type Thermoelectric Materials
Authors: Kinemuchi Yoshiaki , Kaga Hisashi , Tanaka Satoshi , Uematsu Keizo , Nakano Hiromi , Watari Koji
Published: March 2009

Thermoelectric properties of zinc oxide ceramics are largely influenced by the mobility
variation because of the formation of double Schottky barrier at grain boundary. It was demonstrated
that magnetic texturing enabled to fabricate highly c-axis oriented ceramics with orientation degree of
100 MRD. This high orientation of grains resulted in periodic grain boundary structures along ab
-plane, which was confirmed by edge-on HRTEM images. Hall measurement revealed that the
mobility was enhanced at 80% by the magnetic texturing. Furthermore, it was estimated that the effect
of magnetic texturing was equivalent to the reduction in the density of trap by 5.9×1012 cm-2.
Spark Plasma Sintering of βSiAlON-cBN Composite
Authors: Hotta Mikinori , Goto Takashi
Published: March 2009

βSiAlON-cubic boron nitride (cBN) composites were prepared from β-SiAlON and cBN
powders using spark plasma sintering (SPS) at firing temperature of 1600-1900oC under pressure of
100MPa, and densification, phase transformation and hardness of the composites were investigated.
The phase transformation of cBN to hexagonal BN (hBN) was inhibited in βSiAlON-cBN composite.
βSiAlON-cBN composites containing 10-30 vol% cBN fired at 1650oC were densified to 95-98% of
theoretical density with no transformation of cBN to hBN. Vickers hardness of the βSiAlON-cBN
composite containing 20 vol% cBN fired at 1650oC was 17.5 GPa in maximum value, and the
hardness significantly decreased as cBN phase was transformed to hBN in the composites.
Effect of Calcination on Mechanical Properties of Hydroxyapatite / Zirconia Composite Sintered by Spark Plasma Sintering
Authors: Moon Byung Kyu , Kamada Kai , Enomoto Naoya , Hojo Junichi , Lee Soo Wohn
Published: March 2009

The effect of calcination on the mechanical properties of hydroxyapatite and zirconia
composite (HAp:ZrO2= 30:70, 50:50, 70:30 mass%) was investigated. The calcination of ball-milled
mixture in air at 900°C for 0, 2 and 4 hours increased the crystallinity. Then, it was assigned that the
particles form of hydroxyapatite was changed from needle-like to sphere-like by calcination. The
calcined mixture was sintered by spark plasma sintering (SPS) at 1200°C with a pressure of 40MPa
for 5 minutes. The calcination process caused the enhancement of flexural strength of the composite.
The Nanohardness of Acicular Ferrite and Bainitic Ferrite in Low Carbon Microalloying Steel
Authors: Shang Cheng Jia , Liang X. , Wang Xue Min , He Xin Lai , Liu H.
Published: March 2009

Dynamic continuous stiffness measurement (CSM) nanoindentation method was applied to
measure nanohardness in low carbon microalloying steel. The matrix hardness for quenched phase
and acicular ferrite calculated through analysis of curves is less fluctuated than the raw results, which
shows that the analysis of the curves is helpful for determining matrix hardness.
Effects of SiO2 Particles on Wear Behavior of Cu-SiO2 Dispersion-Hardened Alloys
Authors: Sato Hisashi , Watanabe Yoshimi
Published: March 2009

Effects of solid particles on wear behavior of dispersion-hardened alloy were investigated
using Cu-SiO2 alloys containing 0.6vol.%SiO2, 1.2vol.%SiO2 and 1.7vol.%SiO2 particles. Wear tests
were made using pin-on-disc type wear machine. Wear property of the Cu-SiO2 alloys is improved by
increasing volume fraction of SiO2 particles. Moreover, wear amounts of Cu-SiO2 alloys increase
with increasing the sliding distance, and then are saturated at exceeding about 1km. This is why that
SiO2 particle improves the strength of Cu-SiO2 alloy, and that the work hardening occurs on worn
surface. Wear-induced layer is formed just below worn surface by severe plastic deformation due to
wear, and its hardness increases as the volume fraction of SiO2 particles increases. From these
obtained results, wear process of Cu-SiO2 alloy was discussed.
Oxidation Behavior of Ti3SiC2-SiC Ceramic Composites
Authors: Zhu De Gui , Wang Zhi Gang
Published: March 2009

The high temperature oxidation behaviors of the Ti3SiC2-SiC ceramic composites
fabricated by in situ synthesis under hot isostatic pressing were studied by DSC. The results show that
the growth of the oxide scales on Ti3SiC2-SiC ceramic composites obeys a parabolic law in air. The
oxidation resistance at 1400°C is better than that at 1200°C for long time. The oxidation resistance of
the Ti3SiC2-SiC ceramic composites is much higher than that of monolithic Ti3SiC2. The mechanism
of oxidation of Ti3SiC2-SiC ceramic composites is discussed.
Effects of the Morphology of Silicon Phase on the Properties of Zinc Based Composites
Authors: Wei Ai Li , Song Wei , Wu Xiao Dong , Liang Wei , Xu Li Hua
Published: March 2009

This paper deals with the microstructure and property of zinc based composites ZA27Six
under the treatment of the sodium salt and the rare earth. The test material was prepared with pure zinc
ingot (Zn≥99.99wt %) and the Al-Si matrix alloy. Basic composition of the test sample was Al (25~30
wt %), Si (2.5~6.0 wt %) and Zn for the rest. Impact toughness test, tensile test and wear test were
conducted. The test results show that under the treatment of sodium the massive primary silicon
crystal can transform to nodular silicon on which eutectic silicon crystal can form and grow in
rod-like. It is also found that the combined effect of rare earth and sodium salt can obviously refine the
silicon phase and the zinc based composites enhanced by nodular silicon has better hardness and
wear- resistance.
Measurement of Strain and Stress Distribution of Composite Materials by Electron Moiré Method
Authors: Kishimoto Satoshi , Tanaka Yoshihisa , Xing Yong Ming , Lee Gyu Chang
Published: March 2009

A method for measuring the stress and strain distribution in the composite materials and
residual stress at the interface in the fiber reinforced composite has been developed. The strains are
measured using an electron Moiré method and then the stresses are calculated from these strains. A
very fine model grid with frequencies up to 10,000lines/mm can be fabricated using the optical and
electron lithography techniques on the surface of the specimen and an electron beam scan which
spaces are almost same as that of model grid the can be used for master-grid. The difference of the
amount of secondary electrons per a primary electron makes Moiré fringes that consists bright and
dark parts. Micro-creep deformation and residual strain and stress near the fibers of composite materials
were measured by this method.
Study on In Situ Synthesized Titanium Matrix Composites
Authors: Zhang Di , Lu Jun Qiang , Lu Wei Jie , Qin Ji Ning
Published: March 2009

In the present work, titanium matrix composites reinforced with TiB, TiC, and Re2O3
(Nd2O3 or Y2O3) were fabricated via common casting and hot-forging technology utilizing the
chemical reaction between Ti, B4C (or C), rare earth (Re) and B2O3
through homogeneously melting
in a non-consumable vacuum arc remelting furnace. In this work, Nd and Y were chosen as rare earth
(Re) added in the in situ reaction. The thermodynamics of in situ synthesis reactions was studied. The
results of X-ray diffraction (XRD) proved that no other phases appeared except for TiB, TiC and
Re2O3. The microstructures of the composites were examined by optical microscopy (OM). The
results showed that there were mainly three kinds of reinforcements: TiB whiskers, TiC particles and
Re2O3
particles. The reinforcements were fine and were homogeneously distributed in the matrix. The
interfaces of TiB-Ti and Y2O3-Ti have been examined by high-resolution transmission electron
microscopy (HREM).Transmission electron microscopy (TEM) and selected area diffraction (SAD)
were used to analyze the orientation relationships of TiB-Ti, Nd2O3-Ti, and Y2O3-Ti. The mechanical
properties at room temperature improved with the addition of TiB whiskers and TiC particles
although some reduction in ductility was observed. The (TiB+TiC)/Ti6242 composite with
TiB:TiC=1:1 shows higher tensile strength and ductility.
An Amendment Method for Stress and Strain of Double-Curved Laminated Composite
Authors: Liu Yong Shou , Liu Jun , Wang An Qiang , Yue Zhu Feng
Published: March 2009

In this paper, an amendment method for stress and strain of double-curved laminated
composite is proposed and studied. According to finite element analysis results of the same model
with two different mesh size (coarse mesh size 120mm× 300mm and refined mesh size
30mm× 30mm ), stress and strain have been amended with modified formula in user material
subroutine (UMAT) subprogram so that the corrected results of model with coarse mesh is similar to
the results of model with refined mesh. Using this method, with coarse mesh, a satisfied accuracy
results still can be obtained without refining mesh. It’s efficient for design and analysis of complex
structures.
The Effect of Matrix on the Mechanical Properties of Squeeze Cast Al - 50 % SiCp Composites
Authors: Mindivan Harun , Kayali S. , Çimenoğlu H.
Published: March 2009

This study has been conducted to investigate the mechanical properties of aluminum
matrix 50 vol.% SiC particle (SiCp) reinforced composites produced by a squeeze casting technique.
Commercial 2618, 6082, and 7012 aluminum alloys were utilized as the matrix material.
Composites were tested in as-cast and T6-tempered states. Mechanical properties of the composites
were determined by hardness measurements and impact tests. As-cast composites exhibited lower
hardness along with a better impact resistance than their T6-tempered states. After T6-tempering the
hardness of 7012 matrix composite reached to a value of 324 HV2, which is comparable with the
hardness of quenched and tempered steels.
Numerical Analysis of Force and Power Parameters in Cold Ring Rolling
Authors: Guo L.G. , Yang He
Published: March 2009

During cold ring rolling process, the accurate prediction and analysis of force and power
parameters, including roll force (RF) and roll moment (RM), is important in selecting, designing and
developing the forming rolls and cold ring rolling mills. In this paper, a three-dimensional
elastic-plastic dynamic explicit FE model of cold ring rolling process has been presented and
validated in terms of roll force and geometry development. Based on the model, the variation laws of
force and power parameters under different sizes of forming rolls (including driver roll and idle roll)
and forming parameters (including the rotational speed of driver roll 1 n and the feed rate of idle roll
v ) have been revealed by comprehensive numerical simulations.
Butt Joining of Dissimilar Sheets by Shot Peening
Authors: Harada Yasunori , Fukunaga Makoto , Fukaura Kenzo , Ujihashi Satoru , Kobayashi Yuji
Published: March 2009

The butt joining of dissimilar sheets using a shot peening process was investigated. Shot
peening is a surface treatment and improves the performance of engineering components. In shot
peening, the substrate undergoes a large plastic deformation near its surface due to a hit with many
shots. Thus, plastic flow characterized by a shear droop occurs at the edge of the substrate due to shot
peening. When the dissimilar sheets with the edge of the notch geometry are connected without level
difference and shot-peened the connection, the sheets can be joined due to the plastic flow generated
by the large plastic deformation during shot peening. In the experiment, a compressed-air-type shot
peening machine was employed. The influences of processing conditions on the joining of the
dissimilar sheets were examined. The joint strength increased with the kinetic energy of shots. It was
found that the present method using shot peening process was effective in joining dissimilar sheets.
Optimization of Residual Manganese in Molten Metal in Basic Oxygen Furnace (BOF)
Authors: El Hady O.A. , Amer Amer E. , El Mahallawi I.S. , Shash Y.S.
Published: March 2009

At the Egyptian Iron and Steel Company, attention is constantly focused on
improving basic steel making practice with the aim of improvement of blowing
regime and the addition of forming slag materials system.
A number of factors considered important in controlling the properties of steel
products and affecting the residual manganese in the basic Oxygen furnace (BOF)
have been investigated by changing some industrial parameters, aiming at optimizing
the residual manganese in BOF. The studied factors were manganese oxide in the
slag, iron oxide in the slag, tapping temperature, Slag basicity, Lance height, blowing
time, and carbon content.
It was found that residual manganese increased from 0.25 to 0.35 % wt, due to the
reduction of both MnO in slag from 22% to 15% and FeO from 21 to18%, also the
increase of tapping temperature from 1650 oC to 1670 oC caused an increase the
residual manganese from 0.27% to 0.35%, and the slag basicity decrease from 4.25 to
3.8 led to an increase in the residual manganese from 0.25 to 0.37%. Also, the change
of the lance height from 1050 mm to 825 mm caused an increase in the residual
manganese from 0.27 % to 0.33 %.
These results are believed to be reflected on the total energy consumption and ferromanganese
additions needed for producing specific grades.
Lining of Carbon Steel with Metal Foils by Shot Peening
Authors: Harada Yasunori , Fukaura Kenzo , Kim Dae Gi
Published: March 2009

A lining process for carbon steel using shot peening was investigated. In the shot peening
experiment, the dissimilar foil set on the carbon steel substrate is pelted with many shots at a high
velocity. The foil is bonded to the surface of the substrate due to plastic deformation induced by the
collision of the shots. In the experiment, an air-type shot peening machine with an electrical heater
was employed. The substrates are commercially carbon steel S45C, and the foils are commercially
pure aluminum, pure copper, and pure nickel. The effects of shot conditions and the heating
temperature on the joinability were examined. To improve surface characteristics such as wear
resistance and corrosion resistance, the surface alloying of the lined workpiece was also attempted.
The metal foils were successfully joined to the surface of the substrate. It was found that surface
properties of carbon steel could be improved by the shot lining process.
Preparation of Homogeneous Fe-Al Intermetallic Compound Sheet by Multi-Layered Rolling and Subsequent Heat Treatment
Authors: Nishimoto Akio , Akamatsu Katsuya
Published: March 2009

Iron aluminides exhibit good resistance to high-temperature oxidizing and sulphidizing
environments and have potential for structural applications at high temperatures under corrosive
environments. In this study, an Fe-Al intermetallic compound was prepared by multi-layered
roll-bonding of elemental Fe and Al foils. The process consisted of the accumulative roll-bonding
(ARB) for making a laminated Fe/Al sheet and the subsequent heat treatment promoting a
solid-phase reaction in the laminated Fe/Al sheet. Accumulated foils were rolled and bonded at
room temperature or 573 K. A pulsed electric current sintering (PECS) process was used for the
subsequent heat treatment. The microstructures produced at each processing stage were
characterized by optical microscopy and scanning electron microscopy (SEM) equipped with
energy-dispersive X-ray spectroscopy (EDS). Vickers microhardness testing was used for hardness
determination. A homogeneous intermetallic compound of Fe3Al or FeAl could be obtained after
the subsequent heat treatment for 1.8 ks at 873 K and for 3.6 ks at 1173 K.
Preparing Semisolid Light Alloys by Vibrating Wavelike Sloping Plate Process and Thixoforming
Authors: Guan Ren Guo , Xing Zhen Huan , Shi Lu , Wang Chao , Wang Yi
Published: March 2009

By using self-made vibrating wavelike sloping plate setup, semisolid billets with fine spherical or
rosette grains have be prepared by semi-continuous casting, and the solidified shell on the sloping plate surface
can be effectively avoided. Burst nucleation in the whole melt and dendrite fracture causes the formation of fine
spherical microstructures. Under the current experimental conditions, proper casting temperature ranges of
660°C~680°C and the amplitude value of under 2mm proper are suggested. When the reheating temperature is
575°C and the holding time is 60min for AZ91D alloy, 597°C and 90min for Al-6Si-2Mg (wt-%) alloy, semisolid
forging process can be successfully implemented. Thixo-forming products of two alloys are fine with smooth
appearance, good microstructures and properties.
Measurement of Cutting Temperature Using Wireless Sensing System
Authors: Ho Ching Yen , Lee Yi Chwen , Tzeng Yih Shyang
Published: March 2009

This paper utilized a wireless temperature sensing system to measure the temperature
histories of tool and workpiece during cutting. It is essential to use a wireless sensing system to
measure the temperature in cutting and monitor the cutting process due to tool movement, workpiece
turning, network monitoring and safety consideration. The temperature sensing system includes the
wireless transmitter and receiver, A/D and D/A converter, data processing software, and computer.
The temperature histories for different feed rates and depths of cut were measured in real time during
cutting. The data measured by using wireless temperature sensing system were also compared with
these obtained from an infrared thermometer.
Mechanical Properties of Equal Channel Angular Extruded Magnesium Boride (MgB2) Powder in Tubes (PITs)
Authors: Nagasekhar A.V. , Yip Tick Hon , Guduru R.K. , Ramakanth K.S.
Published: March 2009

The MgB2 PITs, prepared by filling Fe tubes with MgB2 as a core, were processed
through different number of passes at room temperature via Routes A, BA, C and BC. The
mechanical properties of the PITs were measured in terms of density and hardness. The extent of the
compaction was also studied through shear punch test. The shape of the compacts remains circular
even after four passes via Route C & BC. Higher density and hardness along with higher USS is
observed from the PITs of Route C compared to Route BC. The PITs processed through Route A
and Route BA did not show sufficient compaction to carryout the density measurements. Thus, the
current study shows that Route C is the optimal route; to attain good mechanical properties in
ECAE processed MgB2 PITs with Fe tube.
Coating with Supersonic Free-Jet PVD
Authors: Niwa Naotake , Yumoto Atsushi , Yamamoto Takahisa , Hiroki Fujio , Shiota Ichiro
Published: March 2009

Recently, requirements for structural materials become increasingly severe. A coating is
one of the most promising methods to achieve the requirements. However, conventional coating
processes generally have technical problems. We apply Supersonic Free-Jet PVD (SFJ-PVD) to
coating. The SFJ-PVD is a technique to deposit nanoparticles with supersonic gas flow and to form
a thick coating film without a crack or a void. This method is composed of “gas evaporation” and
“vacuum deposition”. In a gas evaporation chamber, a source material is evaporated to form
nanoparticles in an inert gas atmosphere. The nanoparticles are then carried to a substrate in a
deposition chamber with an inert gas flow through a transfer pipe. The gas flow is generated by the
pressure difference between the chambers and accelerated through a supersonic nozzle. With SFJPVD,
We obtain uniform several hundreds micron meter-thick, high-density coatings.
Diameter Effect on Detonation Velocity of Ammonium Nitrate and Activated Carbon Mixtures
Authors: Miyake Atsumi , Kobayashi Hidefumi , Echigoya Hiroshi , Katoh Katsumi , Kubota Shiro , Wada Yuji , Ogata Yuji , Ogawa Terushige
Published: March 2009

To obtain a better understanding of detonation properties of ammonium nitrate (AN) and
activated carbon (AC) mixtures, steel tube test with several diameters was carried out for various
compositions of powdered AN and AC mixtures and the influence of the charge diameter on the
detonation velocity was investigated. The results of test indicated that the detonation velocity
increased with the increase of the charge diameter. The experimentally observed values were far
below the theoretically predicted values made by the thermohydrodynamic CHEETAH code and
they showed so-called non-ideal detonation. The extrapolated detonation velocity of stoichiometric
composition to the infinite diameter showed a good agreement with the theoretical value.
A Study of the Weld Zones on Explosive Cladded Titan12/Ss 304 L Plates
Authors: Raghukandan Krishnamorthy , Tamilchelvan P. , Meikandan N.
Published: March 2009

Explosive cladding is a non-conventional, solid-phase bonding technique in which
bonding between two plates is produced by their high velocity collision induced by the use of
explosives. Attempts were made to explosive clad Titanium-Stainless steel (SS 304 L) plates (3.5
and 3.0 mm thick respectively). The experiments were designed to analyze the bonding interface
parallel to the detonation direction. The presence of intermetallics, caused by the melting at the
interface due to kinetic energy dissipation, was observed in some locations. The process parameters
of the explosive welding of Titanium-Stainless steel combination are defined using the
microstructural observations, microhardness at the interface, the results of X-ray diffraction study.
A weldability window is also constructed for explosive welding of Ti /Ss.
Numerical Simulation of Underwater Explosive Compaction Process for Compaction of Tungsten Powder
Authors: Zohoor Mehdi , Mehdipoor A.
Published: March 2009

Underwater explosive compaction is a modified explosive compaction process that is used for manufacturing of parts by compaction of hard powders such as tungsten powder. In the present research work, equation of state (EOS) for tungsten powder was determined by a theoretical method and numerical simulation of the underwater explosive compaction process for tungsten powder was done using LS-DYNA program. The simulation results were utilized for the optimization of die design setups, which were used in our experimental test. Several experiments for compaction of tungsten amorphous powder with a mean grain size about 5 microns were performed using C4 explosive with a detonation velocity about 8.2 km/s. The hardness and density of consolidated samples were determined. The fragmented surfaces of samples were analyzed by scanning electron microscope (SEM). The experimental results indicated the usefulness of computer simulation for optimization of die design and the process parameters. In addition, the results indicated that the tungsten parts without cracks and with a high relative hardness and density could be obtained by underwater explosive compaction method.
Fatigue Failure under Varying Loading within Fatigue Limit Diagram
Authors: Kondo Yoshiyuki , Eda H. , Kubota Masanobu
Published: March 2009

Although fatigue limit diagram is defined in principle for constant stress amplitude
condition, it is often considered that fatigue failure would not occur even in varying loading if applied
stresses were kept within the fatigue limit diagram. However, it was shown in the case of
small-notched specimen and fretting fatigue that fatigue failure occurred in some special case of
variable amplitude loading condition even when all stress amplitudes were kept within the fatigue
limit diagram. The cause of this phenomenon was examined using two-step and repeated two-step
stress patterns in which the first step stress was with zero mean stress and the second step stress had a
high mean stress. A non-propagating crack was formed by the first step stress. This crack functioned
as a pre-crack for the second step stress with high mean stress. Consequently, fatigue failure occurred
even when all stress amplitudes were kept within the fatigue limit diagram. It was an unexpected
fracture caused by the interference effect of non-propagating crack and mean stress change.
Microstructure-Aided Analysis of Fatigue Thresholds in Duplex Stainless Steel
Authors: Pokluda Jaroslav , Podrábský Tomáš , Slámečka Karel , Hutařová Simona , Chai Guo Cai
Published: March 2009

High fatigue threshold values of duplex ferritic-martensitic steels are interpreted by using
a unified model of roughness- and plasticity induced crack closure. Complex metallographical and
fractographical analysis was performed in order to obtain characteristics of tortuous crack paths
produced by crack deflection and branching mainly at austenite/ferrite interfaces. Calculated values
of effective thresholds are in a good agreement with experimental data. The total level of extrinsic
toughening (closure + shielding) induced by the duplex microstructure was determined to be as
much as 70% of measured fatigue threshold values. This is the main reason for the high resistance
to propagation of long fatigue cracks in the near-threshold region.
Analysis of a Transversal Crack in a Steel Slab
Authors: Dobrovská Jana , Stránský Karel , Kavička František , Stetina Josef , Franek Zdenek
Published: March 2009

This paper deals with an analysis of the possible causes of a transversal crack in a steel
slab with a l300×l45 mm cross-section using results from two models. Samples were taken from
and around the crack in order to analyze the concentration (i.e. chemical heterogeneity) of the
relevant elements. Simultaneously, the concentration of elements at the surface of the crack was
measured after the crack was opened. The chemical heterogeneity of elements was analyzed with
the aid of the JEOL JXA 8600/KEVEX analytical equipment. The measurement results were
processed using mathematical statistics procedures. The results proved that there was an internal
crack initiating immediately below the curve of the solid-state temperature and consecutively
propagating.
Yield Surface and Complex Loading Path Simulation of a Duplex Stainless Steel Using a Bi-Phase Polycrystalline Model
Authors: Evrard Pierre , Aubin Veronique , Degallaix Suzanne , Kondo Djimedo
Published: March 2009

In order to model the elasto-viscoplastic behaviour of an austenitic-ferritic stainless
steel, the model initially developed by Cailletaud-Pilvin [1] [2] and used for modeling single-phase
polycrystalline steel is extended in order to take into account the bi-phased character of a duplex
steel. Two concentration laws and two local constitutive laws, based on the crystallographic slips
and the dislocation densities, are thus simultaneously considered. The model parameters are
identified by an inverse method. Simple tests among which tension test at constant strain rate and
at different strain rates and uniaxial tension-compression test are used during the identification
step. The predictive capabilities of the polycrystalline model are tested for non-proportional loading
paths. It is shown that the model reproduces the over-hardening experimentally observed for this
kind of loading paths. Then, yield surfaces are simulated during a uniaxial tension-compression
test: it is shown that the distortion (i.e. plastic anisotropy induced by loading path) is correctly
described.
FGM Structure Characterization by Distance Functions and Systematic Scanning Method
Authors: Chrapoński Jacek , Maliński Marian , Szala Janusz , Cwajna Jan
Published: March 2009

The distance functions such as G(r), K(r), H(r), g(r) and systematic scanning method
connected with variance analysis have been used for quantitative characterization of functionally
gradient materials structures. The methods have been tested on computer generated 3D model
polycrystalline structures with diverse type of gradient function. Usefulness of the presented
methods for quantitative description of FGM structures has been evaluated.
Interdiffusion and Order Fracture over Grain Boundaries in the Deformed Ni3Al Intermetallide
Authors: Starostenkov Mikhail D. , Poletaev Gennady M. , Rakitin Roman Y. , Sinyaev Dmitry V.
Published: March 2009

The peculiarities of diffusion process and changes of long and short order parameters at
an elastic and plastic deformation of compression and tension near grain boundaries with
disorientation axis <111> are studied by the method of molecular dynamics. Whirl displacements of
atoms destroying the order near grain boundary superdislocations are noticed at uniaxial
deformation of compression. The fracture of superstructural and structural order at uniaxial
deformation is accompanied by the deformation of amorphous area. Interdiffusion mechanism is
changed in the dependence on deformation, temperature and boundary types.
Structural Non-Homogeneity and Thermal Instability of ECAP Aluminium
Authors: Saxl Ivan , Ilucová L. , Svoboda Milan , Sklenička Václav , Betekhtin Vladimir I. , Kadomtsev Andrey G. , Král Petr
Published: March 2009

The grain structure of pure aluminium processed by equal channel angular pressing
(ECAP) was examined electron backscattered diffraction (EBSD) in the as pressed state and after
heating preceding the creep deformation using various stereological methods. Area intensities of
grain and subgrain boundaries, length intensities of triple grain and subgrain junctions, structural
homogeneity and its thermal stability are strictly dependent on the number of passes.
Structure and Properties of PM Nano-Crystalline Al-Cr based Alloys
Authors: Vojtech Dalibor , Michalcová Alena , Verner Jan , Šerák Jan , Šimančík František , Balog Martin , Nagy Juraj
Published: March 2009

In the presented paper, properties of Al-Cr-Fe-Ti alloy produced by powder metallurgy
(PM) are described. Rapidly solidified powder alloy was prepared by the pressure nitrogen melt
atomization. The granulometric powder fraction of less than 45 μm was then hot-extruded.
Microstructure of the as-extruded material comprised recrystallized α-Al grains and spheroids of
intermetallic phases. Tensile strength of the investigated material was similar to that of a
conventional casting Al-Si alloy commonly used in elevated temperature applications. Excellent
thermal stability of the PM Al-Cr based material, which much exceeded the elevated temperature
casting alloy, was proved by room temperature tensile tests after long-term annealing at elevated
temperature. Reasons for the observed thermal stability of the investigated PM alloy are discussed.
Estimation of the Crack Propagation Direction of a Crack Touching the Interface between Two Elastic Materials
Authors: Náhlík Luboš , Šestáková Lucie , Hutař Pavel
Published: March 2009

The objective of the paper is to investigate the direction of a further crack propagation
from the interface between two elastic materials. The angle of crack propagation changes when the
crack passes the interface. The suggested procedure makes it possible to estimate an angle of
propagation under which the crack will propagate into the second material. The assumptions of
linear elastic fracture mechanics and elastic behavior of the body with interfaces are considered. The
finite element method was used for numerical calculations. The results obtained might contribute to
a better understanding of the failure of materials with interfaces (e.g. layered composites, materials
with protective coatings) and to a more reliable estimation of the service life of such structures.
F2-Laser Angle Nanomodification of PET
Authors: Slepička Petr , Heitz J. , Siegel Jakub , Špírková M. , Švorčík Václav
Published: March 2009

This work is focused on laser modification of polymers with different angles of
incidence. Periodic surface structures generated by linearly polarized F2 laser light (157 nm) on
polyethyleneterephthalate (PET) were studied. Atomic force microscopy was used to study the
topological changes induced by the laser irradiation. The laser irradiation induces the formation of
periodic ripple structures, the width of and the height being angle dependent. The periodic structures
were formed with the laser fluence 4.70 mJ/cm2. The laser modified PET foils were coated with a
50 nm thick gold layer by sputtering. After Au deposition on the laser PET foils with ripple
structure, the roughness of surface decreases in comparison to PET with ripples without Au coating.
Influence of Al-Si Layer on Structure and Properties of Cast Ni-Based Superalloys
Authors: Hutařová Simona , Vlasák Tomás , Podrábský Tomáš , Hakl Jan , Juliš Martin
Published: March 2009

High-temperature constructional parts of aircraft engines and energy units are exposed to
high dynamic stress (fatigue processes and creep) and various temperatures in dioxide-corrosion
condition (hot corrosion, oxidation and erosion). The improvement of aero-engine and turbine
efficiency is possible through the increase of temperature in front of turbine. This requires the use of
heat-resistant and creep-resistant materials, especially nickel-base superalloys which resist
mentioned effects for a limited period of time. A deposition of protective layers should improve hot
corrosion resistance. This paper is focused on microstructure of protective layers created by codeposition
of Al and Si on nickel-base superalloys INCO 713 LC and INCO 738 LC after thermal
and thermal-stress exposition and on microstructure of basic materials (substrates). The contribution
also shows creep tests results for both superalloys with and without a protective layer.
Growth of Metallic Crystals by Floating Zone Technique with Optical Heating
Authors: Lejček Pavel , Kopeček Jaromír
Published: March 2009

Well-characterised samples such as single crystals, bi-, tri- or multicrystals are needed for
basic studies of properties of solids. Growth of such metallic structures by means of the floatingzone
melting technique is demonstrated for iron base alloys, FeAl intermetallics and NiTi shape
memory alloy.
Classification and Computer Simulation of 2D Tessellations
Authors: Ponížil Petr , Saxl Ivan , Procházka Jaroslav
Published: March 2009

In an analogy to the 3D tool of tessellation classification – w−s diagram, a similar
graphical device is proposed for 2D tessellations. Any tessellation is represented by a point in the
Cartesian coordinate system with the axes Ep (the mean cell perimeter) and CV a (the coefficient of
cell area variation). Images of tessellations and p−CV a diagrams for selected tessellations with low
and high values of CV a are shown as examples.
Fracture Behaviour of Fe3Al and FeAl Type Iron Aluminides
Authors: Kubošová Andrea , Karlík Miroslav , Haušild Petr , Prahl J.
Published: March 2009

Fracture behaviour of two intermetallic alloys based on FeAl and Fe3Al was studied. On the
alloys Fe-40Al-1C (at%) and Fe-29.5Al-2.3Cr-0.63Zr-0.2C (at%) (FA06Z), a basic characterization,
the fracture toughness tests and fractographic analysis were carried out. Tensile tests
and fracture toughness tests were performed at 20, 200, 400 and 600°C. The fracture
toughness values range from 26 MPa.m1/2 at 20°C to 42 MPa.m1/2 at 400°C. In addition, Jintegral
dependence on a obtained by potential method was measured. The fractographic
analysis showed that samples fractured at 20, 200 and 400°C in the tensile or fracture
toughness tests exhibit transgranular cleavage fracture, while at 600°C the ductile dimple
fracture predominates.
Effect of Heat Treatment on Microstructure and Mechanical Properties in ZK60 Alloy Sheet
Authors: Kang Suk Bong , Cho Jae Hyung , Kim Hyoung Wook , Jin Y.M
Published: March 2009

The sheet of ZK60 alloy with a thickness of 1mm was prepared from a casting ingot
followed by homogenization and warm-rolling. Variations in microstructure and mechanical
properties of ZK60 alloy sheets were investigated during T6 treatment. Especially artificial aging after
solution heat treatment affected both precipitates distribution and mechanical properties with aging
treatment. Variations of mechanical properties were related to precipitates, i.e. rod-shaped ( 1 β ′ ) or
disc shaped ( 2 β ′ ) particles. Around the peak of hardness values, regularly distributed rod-shaped ( 1 β ′ )
precipitates were found. The rod-shaped ( 1 β ′ ) precipitates were oriented with a growth direction of
[0001]. When over-aged, rod-shaped ( 1 β ′ ) precipitates were expected to decrease and the density of
disc-shaped ( 2 β ′ ) precipitates to change. The rod-shaped ( 1 β ′ ) precipitates mainly consist of {Mg,
Zn}, while disc-shaped ( 2 β ′ ) precipitates, {Mg, Zn, Zr} or {Mg, Zn}. In this study the optimum T6
treatment was determined as solution treatment at 430 °C for 6 hours and subsequently aging
treatment at 175 °C for 18 hours. At this T6 condition the tensile strength, yield strength and
elongation are 321MPa, 280MPa and 16%, respectively.
Peculiarities of Plastic Deformation and Failure of Nanoparticles of B.C.C. Transition Metals
Authors: Kotrechko Sergiy , Filatov O. , Ovsjannikov O.
Published: March 2009

Atomic mechanisms of the beginning of plastic deformation and failure initiation in nanoparticles of
b.c.c. transition metals are presented in this report. It is shown that strength level of nanoparticles of
b.c.c. transition metals is pre-determined by the lattice instability within the local region of the
crystal. At uniaxial tension even at low temperatures perfect crystal becomes unstable to shear
(„orthorhombic“ path), i.e. local shear instability is the main mechanism of stress relaxation in
nanoparticles of b.c.c. metals. Specific features of local instability of nanoparticle under hydrostatic
tension are considered. A model of the temperature dependence of strength is offered. It is shown
that nanoparticle strength decreases as square root function of temperature with temperature growth.
Just this is essential difference of the temperature dependence of nanoparticle strength from the
same for “ordinary” single- and polycrystals.
Planar Defects on (112) in BCC Crystals
Authors: Ostapovets Andriy , Paidar Vaclav
Published: March 2009

The parameters of exponential many-body Finnis-Sinclair potentials corresponding to
qualitatively different crystal lattice stability were selected and their behaviour was studied.
Furthermore, a model with pairwise Lennard-Jones potential was also considered. The attention was
paid to the stability of different crystal structures and the properties of simple interfaces such as
stacking faults and twin boundaries were investigated.