bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of the Static Recrystallization Kinetics of an Intercritically Deformed C-Mn Steel
Authors: Luo Haiwen , Sietsma Jilt , van der Zwaag Sybrand
Published: March 2009

The austenite recrystallization kinetics in the intercritical region of a C-Mn steel is
investigated by means of stress relaxation tests. It is found that the Avrami exponent, n, decreases significantly with decreasing temperature, i.e. with increasing ferrite fraction. This behaviour deviates from that of austenite recrystallization in the purely austenitic state, in which case the Avrami exponent is constant and independent of temperature and deformation. To interpret this, the influence of spatial variation of the plastic strain in the intercritical austenite grains on recrystallization kinetics is modelled quantitatively. The modelling results seem to indicate that the strain heterogeneity is responsible for the decreasing Avrami exponent with decreasing intercritical temperature.
Effect of Strain on Deformation Microstructure and Subsequent Annealing Behavior of IF Steel Heavily Deformed by ARB Process
Authors: Tsuji Nobuhiro , Kamikawa Naoya , Minamino Yoritoshi
Published: March 2009

Ultra low-carbon interstitial free (IF) steel having ferrite (b.c.c.) single phase was deformed to various equivalent strains ranging from 0.8 to 5.6 by the accumulative roll bonding (ARB) process at 500°C. The microstructure and crystallographic feature of the deformed specimens were characterized mainly by FE-SEM/EBSD analysis. Grain subdivision during the plastic deformation up to very high strain was clarified quantitatively. After heavy deformation above 4.0 of strain, the specimens showed the lamellar boundary structure uniformly, in which the mean spacing of the lamellar boundaries was about 200nm and more than 80% of the boundaries were high-angle ones. Annealing behavior of the ARB processed IF steel strongly depended on the strain. The specimens deformed to medium strains exhibited discontinuous recrystallization characterized by nucleation and growth, while the specimens deformed above strain of 4.0 showed continuous recrystallization. The recrystallization behaviors are discussed on the basis of the microstructural and crystallographic parameters quantitatively measured in the as-deformed samples.
Inhomogeneity of Texture, Particle Precipitation and Grain Size under Recrystallization of Al-Mg , Al-Mg-Li and Al-Mg-Sc Alloys
Authors: Betsofen Sergei Ya. , Lapin A.L.
Published: March 2009

The X-ray rocking curve method (RCM) was used to characterize microstructure and texture of Al and alloys: Al-Mg (AMg6) and Al-Mg-Li (1420), Al- Mg-Sc (1570) after cold rolling to a 8-70 % reduction in thickness, and then annealing at 300-5500C. The fractions of recrystallized grains with {111}, {100}, {113} and {110} orientation in the sheet plane and its distribution on the sizes was measured by a RCM. For these alloys a grains with orientation of {111} and {100} grow much faster than grains {113} and particularly {110}. In an alloy 1420 at 300-4000C continuous recrystallization takes place with fine grains and weakening rolling texture
Recrystallization Behaviour of Two Magnesium Alloys
Authors: Mackenzie L.W.F. , Lorimer Gordon W. , Humphreys John F. , Wilks T.
Published: March 2009

The deformation and recrystallization behaviour of two magnesium alloys, WE43 and an experimental “Alloy A1” containing a large amount of second phase, have been investigated. Optical microscopy and electron backscattered diffraction (EBSD) were used to observe each alloy after deformation in a channel die at 553 and 558 K and subsequent recrystallization during annealing at 673 K. Alloy A1 dynamically recrystallised during deformation at 553 and 558 K. In WE43 the particle distribution affected the onset of dynamic recrystallization. Both alloys exhibited evidence of particle stimulated nucleation (PSN) of recrystallization at second phase particles as well as recrystallization at pre-existing grain boundaries. The A1 and WE43 alloys were extruded at temperatures of 573 K and 633 and 663 K, respectively. The extruded microstructures were compared to those that developed during channel die deformation.
Magnetically Controlled Recrystallization Texture in Titanium
Authors: Molodov Dmitri A. , Sheikh-Ali A.D.
Published: March 2009

The annealing of cold rolled (82%) titanium sheet at 750°C in a magnetic field of 19.4 Tesla results in a distinct difference between texture peaks when the sample is tilted by +30° or -30° to the field direction around the rolling direction, i.e. c (<0001>)-axis of grains corresponding to one texture component is aligned normal to the field direction. This result is attributed to grain growth affected by an additional driving force arising in a magnetic field by the anisotropy of the magnetic
susceptibility of titanium.
Recrystallization of Iron Aluminides
Authors: Skrotzki Werner , Kegler K. , Tamm R. , Oertel C.G.
Published: March 2009

Cast iron aluminides of three compositions were strongly deformed by hot extrusion and subsequently annealed. The texture development and kinetics of recrystallization were determined by local and global texture measurements. The deformation texture of Fe-10Al (A2 structure) is a <110>-fibre, Fe-35Al and Fe-50Al (B2 structure) show a <100>-<110> double fibre texture with <110> dominating Fe-35Al. The texture change with composition is due to a change in slip system. The deformed samples are partially dynamically recrystallized. The recrystallization components are aligned along the symmetry line <100>- <110> and towards <114> for Fe-10Al. For the other alloys the recrystallization texture is <111> with a tendency to <112>. The texture components do not change during static recrystallization. In general, the recrystallization texture is quite weak. The
microstructure is very inhomogeneous ranging from deformed, strongly recovered to recrystallized areas. Beside primary recrystallization abnormal grain growth takes place. The heterogeneity of recrystallization makes it difficult to quantify the kinetics of recrystallization. The results are discussed with respect to the order of the alloys.
Recrystallization and Grain Growth in Rocks and Minerals
Authors: Prior David J. , Bestmann Michel , Halfpenny Angela , Mariani Elisabetta , Piazolo Sandra , Tullis Jan , Wheeler John
Published: March 2009

Misorientation analysis, using EBSD data sets, has enabled us to constrain better
recrystallization mechanisms in rocks and minerals. Observed microstructures are not explicable in terms of recovery, boundary bulging and migration alone. We have to invoke either a nucleation process (physics unknown) or grain rotations that are not related to grain or boundary crystallography. Such rotations can occur by diffusion accommodated grain boundary sliding and this mechanism explains best the microstructure and texture of recrystallized grains in some rocks.
Modelling Recrystallisation during Thermomechanical Processing Using CAFE
Authors: Das S. , Palmiere Eric J. , Howard I.C.
Published: March 2009

A common feature that stimulates modelling efforts across the various physical sciences is that complex microscopic behaviour underlies apparently simple macroscopic effects. Mathematical formulations attempt to capture the initial and evolving microstructural entities either implicitly or explicitly and link their effects to measurable macroscopic variables such as load or stress by averaging out any microscopic fluctuations. The implicit formulations that ignore the inherent spatial heterogeneity in the deforming domain form the basis of constitutive models for
input to finite element (FE) systems. On the other hand, explicit formulations to capture and link microstructural entities rely on narrowing down the size of each finite element, thereby increasing the number of finite elements in the deforming domain, an effect accompanied by a rapid growth in computational time. The model described here, Cellular Automata based Finite Elements (CAFE), utilises the Cellular Automata technique to represent initial and evolving microstructural features
(e.g., dislocation densities, grain sizes, etc.) in C-Mn steels at an appropriate length scale by linking the macro-scale process variables obtained using an overlying finite element mesh. Differences will be illustrated between single and two-pass hot rolling experiments.
Athermal Motion of Grain Boundaries, Twins and Triple Junctions in Zn
Authors: Sursaeva Vera G.
Published: March 2009

When a bicrystal or polycrystal are subjected to a change in temperature, the individual responses of the two adjoining crystals may differ in a manner, which tends to produce a dilatational mismatch along grain boundaries. If compatibility is to be retained along the interface, an additional set of stresses must then be generated in order to conserve this compatibility. ‘Compatibility stresses’ will also be generated whenever a polycrystal is heated or cooled and the thermal expansion coefficients of the individual grains are different due to thermal expansion anisotropy. In such cases adjacent grains will attempt to change dimensions and develop mismatches by amounts controlled by the parameter Δa*ΔΤ, where Δa is the difference between the thermal expansion coefficients in the appropriate directions, and ΔΤ is the temperature change. These ‘compatibility stresses’ may be relieves if grain boundary motion, triple junction migration and grain growth are possible. These ‘compatibility stresses’ may play important role in the kinetic
behavior of the microstructure ranging from influencing the behavior of lattice dislocations near the grain boundaries to promoting grain boundary and triple junction dragging or moving. The motion of the ‘special’ grain boundaries, triple junctions with ‘special’ grain boundaries and twins under the influence of internal mechanical stresses is the main subject of this paper.
Grain Boundary Migration of <110> Tilt Σ11 and Σ27 Boundaries in Pure Aluminum
Authors: Yoshida Fuyuki , Uehara Masato , Ikeda Kenichi , Nakashima Hideharu , Abe Hiroshi
Published: March 2009

Migrations of <110> tilt S 11 and S 27 boundaries in 99.99% purity aluminum have been investigated by Sun and Bauer technique as a function of temperature. In the S 11 tilt boundary, the activation energy for grain boundary migration is about 1/2 of the energy for Al-atom bulk-diffusion, indicating that the boundary motion may be governed by the grain boundary diffusion. While in the S 27 tilt boundary, the activation energy for grain boundary migration is about 125kJ/mol, which
agrees with the energy for Al-atom bulk-diffusion. Study of boundary structure observation by high resolution electron microscopy revealed that the grain boundary structure of S 27 tilt boundary was consisted of edge dislocation array in which a space between dislocations was very short. It is considered that climb motion of the dislocations controlled to the motion of tilt boundaries consisted of edge dislocation array. From these results, it is concluded that the boundary motion of S 27 tilt boundary may be governed by climb motion of their dislocations controlled by Al-atom bulk-diffusion.
Brazed CBN Grinding Wheel with Ag-Base Filler Alloy
Authors: Ding Wen Feng , Xu Jiu Hua , Lu J.B. , Fu Yu Can , Xiao Bing , Xu Hong Jun
Published: March 2009

In this paper, the disadvantages of the current CBN (Cubic Boron Nitride) grinding wheels were firstly introduced briefly, for indicating that it was very urgent and important to develop new kinds of grinding wheels with excellent performance to replace the conventional wheels. Then high temperature brazing experiments of monolayer CBN wheels with Ag-Cu-Ti filler alloy were carried out. The result shows that the filler alloy has good wetting capability towards CBN grits. The results of scanning electron microscope (SEM) and energy dispersion spectrometer (EDS), as well X-ray diffraction (XRD) analysis show that, just because during brazing titanium atoms in filler alloys segregated preferentially to the surface of the CBN to form Ti-nitride or Ti-boride layer by reaction between titanium atoms and nitride and boron atoms at elevated temperature, strong chemical joining was formed in the interface between CBN grits and filler alloys. Finally, the contrastive grinding experiments were performed between the monolayer brazed CBN grinding wheels and the electroplated ones. The results show that the brazed wheels have more excellent performance than the latter.
Three-Dimensional Finite Element Analysis of Metal Powder Compaction
Authors: Chen Pu Qing , Xia Wei , Zhou Zhao Yao , Chen Wei Ping , Li Yuan Yuan
Published: March 2009

Metal cutting operations constitute a large percentage of the manufacturing activity. One of the most important objectives of metal cutting research is to develop techniques that enable optimal utilization of machine tools, improved production efficiency, high machining accuracy and reduced machine downtime and tooling costs. Machining process condition monitoring is certainly the important monitoring requirement of unintended machining operations. A multi-purpose intelligent tool condition monitoring technique for metal cutting process will be introduced in this paper. The knowledge based intelligent pattern recognition algorithm is mainly composed of a fuzzy feature filter and algebraic neurofuzzy networks. It can carry out the fusion of multi-sensor information to enable the proposed intelligent architecture to recognize the tool condition successfully.
Compositional Design of Multiphase Composite Ceramic Tool Material Based on the Thermal Shock Resistance and Its Application
Authors: Xu Chong Hai , Huang Chuan Zhen , Ai Xing
Published: March 2009

Thermal shock resistance is one of the primary properties for the ceramic cutting tool materials with perspectives in high speed machining. An optimum model for the compositional design of the composite ceramic tool materials is built based on the thermal shock resistance. The thermal stress fracture resistance factor R is used to characterize the thermal shock resistance of the ceramic material. Results show that the developed (W,Ti)C/SiC/Al2O3 multiphase ceramic tool material can be expected to achieve the highest thermal shock resistance when the volume fraction
of (W,Ti)C and SiC is about 15.8% and 24.8%, respectively. Thermal fracture resistance of the (W,Ti)C/SiC/Al2O3 ceramic tool material is approximately 81-88% higher than that of the pure alumina ceramic when machining the hardened carbon steel, which coincides well with the theoretical prediction from the optimum model. It suggests that the method used here is feasible for the development of ceramic tool materials with designed thermal shock resistance.
Investigation on Performance of QT700-2 Material by Laser Peening
Authors: Yang Judith C. , Zhou Jian Zhong , Zhang Yong Kang , Yang Chao Jun , Lu Jin Zhon
Published: March 2009

With the advent of high-power pulsed lasers, laser peening has emerged as a new and very promising technique to improve the resistance properties of materials to fatigue, wear and corrosion. In this paper, the effect of laser peening on the surface performance of QT700-2 materials was investigated, the parameters of laser peening were optimized by an artificial neural network (ANN) method. A series of experiments was carried out by using a high-power, Q-Switched, pulsed neodymium-glass laser. The microstructure features were analyzed with SEM and the hardness and residual stresses at the surface and in-depth were measured. The results indicate that the depth of hardened layer was about 0.31ı1.40mm for a different shot number of 1-4 times and the compressive residual stress at the surface increases with increasing laser pulse energy, from -165MPa for the low
energy 12J to -410MPa for the higher energy 20J. Laser peening can restrain nucleation of fatigue cracks and improve the fatigue life of nodular cast iron materials.
Neural Network Prediction of Segment Wear in Stone Sawing
Authors: Xu Xi Peng , Zhang Y.F.
Published: March 2009

An investigation was carried out to predict the wear performance of diamond sawblade segments by using a Levenberg-Marquardt backpropagation (BP) neural network. The wear of the diamond segments were measured in circular sawing of natural gray granite in order to train the network and examine its validation. Since the depth of cut and workpiece speed are two main variables in the sawing of a specific granite material with a fixed diamond sawblade, a 2-5-1 structure of BP network was found to be capable of predicting the wear performance. In spite of the limited experimental data, the average value of relative errors between the simulated and measured results was found to be around 10%. Since experimentally measuring of segment wear is a time-consuming job, the trained network was also used to predict the wear performance under a very wide range of operating parameters, which can provide a useful guideline for the optimization of stone sawing.
Development of Nano-TiN Modified Cermet Cutter
Authors: Xie Feng , Yang H.D. , Zhang C.G. , Liu N.
Published: March 2009

Nano technology is a new technology and begun in 1980’s. The paper firstly overviews the development of cermet cutter and its general situation in research, and then introduces the inherent properties owned by nano-technology and nano-material. In the end the nano-TiN modified TiC-based cermet cutter is fabricated and the mechanical properties of the developed cutter are also tested and analyzed. In order to study nano-modification effect, both nano-modified cermet and general cermet have been made. The mechanical properties of two kinds of materials are also measured. By comparing the measured datum, it has been indicated that the nano-modified cermet has better mechanical properties and the nano-modification technology is effective. This presents a new way to increase the toughness of cermet cutter.
Research on Thickness of the Free Confinement Medium in Laser Shock Processing
Authors: Chen Rong Fa , Hua Yin Qun , Yang Judith C. , Zhang Yong Kang
Published: March 2009

In this paper, it has been studied that the thickness of the free confinement medium in the Laser Shock Processing. Then the relationships are analyzed between the peak pressure induced by laser shock and the properties of the free confinement medium. On the basis, the optimum thickness of the free confinement medium is obtained, which ensure not only the optimum LSP effect but also the elimination of the remains of free confinement medium at a time. In the experiments, a kind of
materials of free confinement medium was invented successfully, which is applicable to laser shock processing. The estimation of the free confinement medium theoretical thickness is accorded with the result of the experimental.
Penetration Dynamics of Solid Particles into Liquids High-Speed Experimental Results and Modelling
Authors: Verezub Olga , Kaptay György , Matsushita Tomiharu , Mukai Kusuhiro
Published: March 2009

Penetration of model solid particles (polymer, teflon, nylon, alumina) into transparent model liquids (distilled water and aqueous solutions of KI) were recorded by a high speed (500 frames per second) camera, while the particles were dropped from different heights vertically on the still surface of the liquids. In all cases a cavity has been found to form behind the solid particle, penetrating into the liquid. For each particle/liquid combination the critical dropping height has been measured, above which the particle was able to penetrate into the bulk liquid. Based on this, the critical impact particle velocity, and also the critical Weber number of penetration have been established. The critical Weber number of penetration was modelled as a function of the contact angle, particle size and the ratio of the density of solid particles to the density of the liquid.
Study on the Assorted Non-Asbestos Fiber Reinforce Composite by Beater-Addition Process
Authors: Liu Mei Hong , Li Zhen Hua , Rong Zhou , Yu Xinqi , Cai Ren Liang , Xie Sujiang
Published: March 2009

In order to get rid of health hazard of asbestos fiber, a new kind of non-asbestos fiber reinforce composite by beater-addition process, which is used for sealing and gasket, has been developed to replace traditional asbestos gasket materials. The mechanical properties of the new composite were tested, and the performance between it and asbestos sheet paper were contrasted. Results show that the density, cross direction tensile strength, machine direction tensile strength and
ignition loss at temperature of 300°C of the new composite are 1.19g/cm3, 2.62MPa, 3.15MPa and 15.61% respectively, while the performances of asbestos paper produced under the same condition are 1.26g/cm3, 2.87MPa, 3.24MPa and 12.03% respectively. Excellent performance, low cost and simple manufacture process of the new composite make it is possible to substitute traditional asbestos paper and apply widely.
Evaluation of Eddy Current Inspection on the Defects of Unloading vs. Loading Conditions in the Fiber Reinforced Composite Materials
Authors: Kim Cheol Woong , Lee Jeong Soon , Um Tae Gun , Oh Dong Joon , Song Il
Published: March 2009

It had been impossible to inspect the Eddy Current (EC) since the Fiber Reinforced Composite Materials (FRCM) had the low electric conductivity of resin layer. However, it has been successful for our previous research to inspect the defect using the EC. In the case of loading to FRCM, the researches of relationship between the failure behavior and the variation of EC signals have not been carried out. Therefore, this research focused on the comparison and the evaluation of the EC signals according to the variation of the defect depth using the unloading and the radial-loading FRCM tube. We obtained results are as follow. Firstly, The EC signals similar to that of the unloading specimens could be obtained from the loading specimen of 80% defect. Secondly, Regardless of the unloading and the loading specimens, the defect of 100% and 80% depths had the similar phase angles and Lissajous figures. Finally, it was guessed that the length of micro-cracks distributed at the whole specimens under the loading was less than 60% of the specimen thickness.
Application of Grazing-Incidence Small-Angle X-Ray Scattering Technique to Semiconducting Composite Materials
Authors: Ogawa T. , Niwa H. , Okuda Hiroshi , Ochiai Shojiro
Published: March 2009

Grazing-incidence small-angle scattering (GI-SAXS) technique was applied to self-assembled Ge islands capped with Si. GI-SAXS has a merit over TEM and AFM that the structure of islands buried in a cap layer for stabilization can be evaluated nondestructively. By analyzing the scattering patterns, the size of Ge islands was estimated to be about 5 nm in height and 26 nm in diameter, with the islands density of 4.2×1014/m2. From the best fitting of two-dimensional model intensity to the experiments, the shape of the islands was deduced
Designing a Composite Material for Use in Brake Applications
Authors: Lo Jason
Published: March 2009

Traditionally, automotive brake rotors are made with cast iron. Besides having
economical advantage, cast iron rotor provides many disadvantages due to its weight, such as reduction in fuel efficiency, increase in green house gas emission, and increase in noise, vibration and hardness. With the development of commercial aluminum composites, composite brake rotors are now manufactured. However, the present commercial composite materials are not specifically made for brake application and there are drawbacks. A major drawback is their poor elevated temperature property. In this paper, the unique properties offered by an aluminum composite for brake application is addressed, and an approach to compensate its properties for brake application is highlighted.
Extraction Efficiency in Pulsed Laser Deposited Y2O3:Eu3+ Thin Film Phosphors on Corrugated Substrates
Authors: Yoo Jeong Gon , Park Duk Hyun , Shin Namsoo , Kim Ji Sik , Sohn Kee Sun
Published: March 2009

The luminance level of thin film Y2O3:Eu3+ phosphors deposited by a pulsed laser
deposition (PLD) technique are not acceptable for field emission display (FED) because of so-called wave guiding effect. Corrugated glass plates were employed as a substrate in order to relieve the wave guiding effect and in turn improve light extraction efficiency of Y2O3:Eu3+ thin film phosphors. Integrated photoluminescent efficiency, film surface roughness and crystallinity were monitored as function of the pitch of corrugation. The integrated photoluminescence efficiency of Y2O3:Eu3+ thin
film phosphor deposited on the corrugated substrate was promoted significantly. The corrugated substrate makes it possible not only to enhance the roughness of phosphor film surface but also to facilitate the film growth in a specific orientation if the pitch size condition was met.
Pretreatment Processing of Gelcast Green Body before Debinding
Authors: Dai Chun Lei , Yang Jin Long , Huang Yong
Published: March 2009

Gelcasting is a novel ceramic forming technology that could be used to manufacture
high-performance ceramics with complex shape. However, there are some problems in debinding of large-size green body made by gelcasting. In this paper, a new pretreatment way before binder burn-out was introduced. By means of this pretreatment processing, large-size green bodies with no defects were successfully obtained.
Crystal Structure and Phase Relationships in the Reduced-Reoxidized Ceria-Zirconia Solid Solution
Authors: Sasaki Tsuyoshi , Ukyo Yoshio , Kuroda Kotaro , Arai Shigeo , Saka Hiroyasu
Published: March 2009

The crystal structures of reduced-reoxidized ceria-zirconia solid solutions, Ce2Zr2O7+x, with an ordered arrangement of Ce and Zr ions were studied by transmission electron microscopy (TEM), X-ray powder diffraction and thermogravimetric analysis. The oxygen absorption of Ce2Zr2O7 with pyrochlore structure (space group m Fd 3 ) was revealed to proceed through two-step
reaction; reaction from Ce2Zr2O7 to b-Ce2Zr2O7.5 around 400K and reaction from b-Ce2Zr2O7.5 to Ce2Zr2O8 about 600K. b-Ce2Zr2O7.5 phase with space group m F 3 4 was thought to be formed by occupation of the half ordered oxygen vacancies with oxygen ions periodically. The oxidation from Ce2Zr2O7 to b-Ce2Zr2O7.5 was also occurred at room temperature by keeping for about 1 year or by irradiation of an electron beam in TEM. On the other hand, the crystal structure of Ce2Zr2O8,
completely oxidized state of Ce2Zr2O7, belongs to the space group of m P 3 4 or 23 P from the rule for possible diffractions and the symmetry of the ordering cations.
Electron Irradiation Damage in Stabilized Cubic Zirconia
Authors: Yasuda Kazuhiro , Kinoshita C. , Matsumura Syo , Ryazanov A.I.
Published: March 2009

We report the formation of anomalous defect clusters in yttria stabilized zirconia (YSZ: 13 mol% Y2O3-ZrO2), which are a primary candidate for inert matrix fuels. Electron irradiation with 100 to 1000 keV is found to induce characteristic defect clusters. The defect clusters show strong black/black lobes contrast and multiply dislocations when the defect clusters grow to a critical diameter of 1.0-1.5 µm. Our analysis with transmission electron microscopy and numerical calculations lead to a conclusion that these defect clusters are charged oxygen platelets formed by the
selective displacements of oxygen sublattice.
Research on Fatigue Properties on Two Kinds of New Developed Zirconium Alloys
Authors: Zhang J.J. , Li Z.K. , Liu J.Z. , Song Q.Z. , Wang Wan Shan
Published: March 2009

Research on low cyclic fatigue behaviors of two kinds of Zr-alloy(1#:Zr-1Sn-0.3Nb- 0.3Fe-0.1Cr.2#: Zr-1Sn-1Nb-0.4Fe-)at 400°C,The fractural characterization was investigated by SEM.
Effects of Heat Treatment on Corrosion of Zr-1.0Nb-1.0Sn-0.1Fe
Authors: Baek J.H. , Jeong Yong Hwan
Published: March 2009

The effects of annealing at 570oC and 640oC on the microstructural and corrosion
characteristics for Zr-1.0Nb-1.0Sn-0.1Fe alloy were elucidated. After annealing at 570oC below the temperature of a monotectoid reaction in the Zr-Nb system, both orthorhombic Zr3Fe and the bcc b-Nb particles were uniformly found and the mean size of the second phase particles was increased with an increasing of the annealing time. In the case of an annealing at 640oC for 2 h above the monotectoid reaction temperature, the Zr3Fe was observed intermittently and after a longer annealing of 1000 h the b-Zr particles were well developed. The corrosion resistance after the 570oC anneal was improved as the annealing time increased, while that after the 640oC anneal decreased as the annealing time increased. The fraction of the tetragonal phase within the ZrO2 oxide increased as the corrosion resistance was improved. It was concluded that the equilibrium Nb concentration and the formation of the tetragonal ZrO2 due to the b-Nb phase would lead to improving the corrosion resistance of the alloy.
Ultra-Fine Grain Size by Dynamic Recrystallization in Strip Rolling of Nb Microalloyed Steel
Authors: Subramanian S.V. , Zhu G. , Klinkenberg Christian , Hulka Klaus
Published: March 2009

The design of base chemistry and optimization of rolling schedule are the two important factors that influence large strain accumulation in multi-pass rolling in order to obtain ultra-fine grain size by dynamic recrystallization. A base chemistry of 0.03C-0.003N-0.08Nb-0.015Ti-1.8Mn (all in weight %) of HTP steel design was chosen in order to control the time evolution of strain induced precipitation of NbC and the strain accumulation through precipitate interaction with recovery and
recrystallization at short inter-pass times characteristic of strip rolling. Experimental data on the critical strain for static and dynamic recrystallisation for HTP steel are used in a quantitative model to predict strain accumulation pass by pass and to achieve grain refinement by dynamic recrystallisation through large strain accumulation. The model is used to optimize the time-temperature-deformation
schedule to prevent static recrystallization during the inter-pass times and to target ultra-fine grain size through dynamic recrystallization by large strain accumulation. The model predictions are validated by simulation of strip rolling of HTP steel on the thermo-mechanical simulator (WUMSI) to obtain a uniform ultra-fine ferrite grain size of about 1.5 micrometer diameter in final ferrite microstructure.
A TEM Study of Cavity Structures in a Fe-Cr-Mn Alloy and a 316L Stainless Steel Heavily Irradiated with 92 MeV Ar Ions
Authors: Zhang Chong Hong , Wang Yue Sheng , Chen K.Q. , Sun Ji Guo , Quan J.M. , Chen Chang Qi
Published: March 2009

Low-activation Fe-Cr-Mn alloy and 316L stainless steel were irradiated with 92 MeV Ar ions at about 500°C, to fluences of 0.8~1.7×1021 ions m-2 .After irradiation, cross-sectional specimens were investigated with transmission electron microscopy.Cavities with high number density were observed in the peak dose regions. The cavity number density reaches maximum at Ar concentration peak, while cavity mean size is consistent with displacement damage profile. It is indicated that Ar atoms can enhance cavity formation in a manner similar to helium. There are thresholds of dose and dose rate for the bi-modal size distribution of cavities. The significant growth of a small portion of cavities in the peak damage region at the highest ion-fluence is ascribed to the effect of interactive sink strength of cavities.
Damage Behavior of Electron/Helium Dual-Beam Irradiation on Fe-Cr-Mn (W, V) Alloy
Authors: Hu Benfu , Kinoshita Hisao , Shibayama Tamaki , Takahashi H.
Published: March 2009

The effect of helium on irradiation damage behavior in Fe-Cr-Mn(W,V) steel was
investigated by electron/helium ion dual-beam irradiation. The results indicate that helium can promote the increase of dislocation density and enhance the void nucleation and void swelling of Fe-Cr-Mn(W、V) alloy. The segregation of solute elements near grain boundary was suppressed by existence of helium. Also the interface of carbide-matrix migration and the change of solute concentration near the interface were observed during dual-beam irradiation.
Fabrication and Evaluation of B4C/Cu FGM as Plasma Facing Materials
Authors: Zhou Zhang Jian , Ge Chang Chun
Published: March 2009

B4C is a promising candidate for using as plasma-facing material in fusion devices. In this paper, both B4C/Cu coating FGM (Funetionally graded material) and B4C/Cu bulk FGM containing a spectrum of 0-100% compositional distributions of B4C were fabricated by atmosphere plasma spray and ultra-high pressure consolidation respectively. The microstructure of B4C/Cu FGM showed good
graded composition distribution. Water quenching and high heat loading experiments using an electron beam were carried out to evaluate the high heat load resistance of B4C/Cu FGMs. The in situ plasma irradiation in a Tokamak facility showed that the B4C/Cu bulk FGM has higher physical sputtering performance than that of B4C/Cu coating FGM.
The Microstructure of Laser Welded V-4Cr-4Ti Alloy after Ion Irradiation
Authors: Watanabe H. , Nagamine M. , Yamasaki K. , Yoshida Naoaki , Heo Nam-Jin , Nagasaka Takuya , Muroga Takeo
Published: March 2009

Laser welded high purity V-4Cr-4Ti alloy (NIFS-HEAT2), fabricated by National Institute for Fusion Science (NIFS), was used for this study. Copper ion irradiation was carried out with the tandem accelerator at Kyushu University. The TEM samples were sliced from the welded materials and irradiated at 573 and 873K up to the dose of 12 dpa. The microstructure before irradiation showed that relatively
large precipitates, which were commonly observed in NIFS-HEAT2, disappeared in the center of the weld metal. After the ion irradiation, fine titanium oxides with {100} habit planes were detected even at the dose of 0.75 dpa. However, less number density of these oxides were observed in the base metal after the same irradiation conditions. This means that the behaviors of oxygen atoms, which dissolved from the large precipitates during the laser welding, is essential to the microstructural evolution of welded V-4Cr-4Ti alloys.
Characterization of Al3Fe Particle within Al-Al3Fe Functionally Graded Material Fabricated by Semi-Solid Forming
Authors: Matsuda Koichi , Watanabe Yoshimi , Yamagiwa Kazuhisa , Fukui Yasuyoshi
Published: March 2009

Near net shape forming of Al-Al3Fe functionally graded materials (FGMs) have been studied. FGM billets fabricated by a centrifugal method were extruded under the condition of a mixture of molten Al eutectic and solid Al3Fe particles. Both distribution and profile of Al3Fe particles were characterized by and the variation of volume fraction of Al3Fe particles was observed. Shore hardness of the Al matrix was also measured to evaluate the strength of the FGM before and after the semi-solid forming associated with the character of distributed Al3Fe particles. It was
confirmed that Shore hardness increased with increasing the volume fraction of Al3Fe particles and after the semi-solid forming than before. This was due to the fact that Al3Fe particles after the semi-solid forming became fine by shear stress introduced by liquid Al flow.
Effects of the Rotating Speed of Centrifugal Machine on the Gradient Structure and Properties of Heavy Cross-Sectional WCP/Fe-C Composites
Authors: Song Yan Pei , Mao Xie Min , Dong Qi Ming , Li Bing Zhe , Liang Hong Yu
Published: March 2009

Effects of the mold rotating speeds on the gradient microstructure and properties of heavy cross-sectional WCP/Fe-C composites made in a self-made centrifugal machine have been investigated with SEM, EDS etc. The results show the ring sample of WCP/Fe-C composites made in a centrifugal machine was free of any defects. And the transition layer between the working layer of WCP/Fe-C composites and matrix Fe-C alloy core was also perfect. The experimental results also show that the WCP-radius-directional distribution in the composites was a continuous component gradient one, which was changed with the various mold rotating speeds. At 1000 rpm the volume fractions of the WC particle from outer layer to inner layer were about 70 vol% to 50 vol% and, at 1400 rpm the volume fractions were about 80 vol% to 65 vol% respectively. The hardness and impact
toughness of the working layer of WCP/Fe-C composites were changed with increasing of the mold rotating speeds respectively. Finally, the mechanism of the effects of the mold rotating speeds was discussed in the paper.
The Properties of W Coatings on Cu by Supersonic Plasma Spray
Authors: Shen Wei Ping , Zhou Zhang Jian , Gu Shu-Yuan , Ge Chang Chun , Zhang Hao , Liu Hai Long
Published: March 2009

Coatings of W on the substrate of oxygen-free Cu have been made by a high efficiency supersonic plasma spray system with a maximum power of 80kW and a maximum working at 6 m3/h flow of gas, and being compared with results of subsonic plasma spray. The bonding strength and thermal shock resistance of the coatings was tested. W/Cu functionally graded coatings is compared with single coatings of W.
Chemical Solution Deposition Process and Characterization of Li and Ti Doped NiO Thin Films
Authors: Zhang Bo Ping , Li Jing Feng , Zhang Li Min , Zeng Jun , Dong Yan
Published: March 2009

Lithium and titanium co-doped NiO ceramics have been found to exhibit a giant
low-frequency dielectric constant (ε～105), however, the same system thin films is not yet study. In the present study, Lithium and titanium co-doped NiO thin films were prepared by a chemical solution deposition method using 2-methoxyethanol as a solvent, nickel actate tetrahydrate, lithium acetate dihydrate and titanium isopropoxide as starting materials. The complex oxides such as NiO, Ni0.2O0.8 and NiTiO3 were formed for the Ni0.98Ti0.02O and Ni0.686Li0.294Ti0.02O thin films, and
the addition of the lithium lead to the formation of Li2NiO2.888. The dielectric constant of Lithium and titanium co-doped Ni0.686Li0.294Ti0.02O thin films is about 426 at 100 Hz and much higher than that of the titanium-doped Ni0.98Ti0.02O.
Combustion Synthesis of Carbide Particle Dispersed Aluminide Intermetallics
Authors: Matsuura Kiyotaka , Hikichi Yusuke , Kudoh Masayuki
Published: March 2009

TiC particle dispersed FeAl intermetallic alloys have been combustion synthesized from mixtures of titanium, carbon, aluminum and iron powders. When the powder mixture was heated in an argon atmosphere to approximately 900 K, an abrupt increase in temperature was observed, which indicates that the combustion synthesis reaction occurred in the powder mixture. The combustion-synthesized alloys consisted of an FeAl matrix phase with homogeneously dispersed fine TiC particles. As the concentrations of titanium and carbon of the powder mixture increased, the volume fraction and average diameter of the TiC particles increased, and Vickers hardness of the sample also increased.
Comparison of Characteristics of BaTiO3 Prepared by Different Process
Authors: Yan Qing Zhi , Zhao Li-Ying , Su Xin Tai , Zhang Wen Feng , Ge Chang Chun
Published: March 2009

Barium titanate powder has been prepared using sol-gel auto-ignition synthesis process and was compared with two commercial high purity BaTiO3 powders prepared by precipitation from oxalate precursor and by hydrothermal synthesis. Characterization by x-ray fluorescence, XRD, field emission scanning electron microscopy, SEM and BET revealed significant difference, particularly in particle size and agglomerate structure, resulting in different microstructure and dielectric property. The sol-gel auto-ignition synthesis process yielded weakly agglomerated powder with average particle size of 50 nm. This property is favorable for sintering and dielectric property.
Growth of an Inx(OOH,S)y Buffer Layer and Its Application to Cu(In,Ga)(Se,S)2 Solar Cells
Authors: Kim Ki Hwan , Larina Liudmila.L. , Yoon Kyung Hoon , Konagai Makoto , Ahn Byung Tae
Published: March 2009

As an alternative to a CdS buffer layer for Cu(In,Ga)Se2-based solar cells, we prepared In-based buffer layers using a chemical bath deposition method. XPS and XRD analyses revealed that the In-based buffer layers contained In2S3 and InOOH phases. Compared with CdS film, the In-based film, Inx(OOH,S)y, had higher optical transmittance and a shorter absorption edge. The Cu(In,Ga)(Se,S)2 solar cell with the Inx(OOH,S)y buffer layer had better photovoltaic properties than that with a conventional CdS buffer layer. The conversion efficiency of the best Cu(In,Ga)(Se,S)2 solar cell with Inx(OOH,S)y buffer layer was 12.55 % for an active area of 0.19 cm2.
Surface Morphology Evolution during LP-MOCVD Growth of ZnO on Sapphire
Authors: Ye Jian Dong , Gu Shu Lin , Zhu Su Min , Liu S.M. , Qin Feng , Liu W. , Zhou X. , Zhang R. , Shi Y. , Zheng Y.D.
Published: March 2009

The morphology evolution of ZnO films grown on sapphire (0001) by MOCVD have been studied as a function of buffer growth time and temperature by means of atomic-force microscope (AFM), x-ray diffractions (XRD) and optical microscopy. When the buffer growth temperature decreased to 450°C, the surface became smooth greatly, indicating the transition from typical 3D island growth to quasi-2D growth mode. As the buffer growth time exceeds 5min, the micron-sized pit-like features are formed. It is due to the lack of stabilization of adatoms under the “etching” action of ionized O2/Ar during high temperature buffer annealing
Structural and Optical Investigation of Mn-Doped ZnS Nanocrystals
Authors: Peng W.Q. , Qu S.C. , Cong G.W. , Wang Z.G.
Published: March 2009

Using a solution-based chemical method, we have prepared ZnS nanocrystals doped with high concentration of Mn2+. The X-ray diffraction analysis confirmed a zinc blende structure. The average size was about 3 nm. Photoluminescence spectrum showed room temperature emission in the visible spectrum, which consisted of the defect-related emission and the 4 T1-6 A1 emission of Mn2+ ions. Compared with the undoped sample, the luminescence of the ZnS:Mn sample is
enhanced by more than an order of magnitude, which indicated that the Mn2+ ions can efficiently boost the luminescence of ZnS nanocrystals.
Raman and Photoluminescence Spectral Study of Eu(DBM)3•2H2O at High Pressures
Authors: Zeng Q.G. , Ding Z.J. , Chen Biao , Zhang Qing Jie
Published: March 2009

The photoluminescence and Raman spectra of the tris(dibenzoylmethane) europium(III) dihydrate (Eu(DBM)3•2H2O) are investigated at high pressures with a diamond anvil cell. For pressures lower than 3 GPa, the luminescent intensities of the Eu3+ ion 5D0→7FJ (J=0, 1, 2, 3, 4)
characteristic peaks increase with the pressure. However, above 3 GPa the intensities decrease. The phenomena indicate that there is energy transition between the Eu3+ ion and the DBM ligand. With the increasing pressure, the intensity for the vibration bands becomes more obvious compared with that of the Eu3+ ion characteristic peaks, as the result of the crystal distortion at high pressures. The Raman bands at low wavenumbers have not shown significant changes with pressure, which manifests that the Eu3+ ion site symmetries are not varied but that the crystal is distorted at high pressures.
Control of Morphology of YBO3:Eu by a Mild Hydrothermal Process
Authors: He Ling , Wang Yu Hua
Published: March 2009

The phosphors YBO3:Eu with different morphology was successfully realized by mild hydrothermal process with different reaction condition. Highly spherical shape, uniform size and non-agglomeration of YBO3:Eu phosphors particle was obtained at 260°C,which is about 850°C lower than that by solid state reactions. The result of XRD showed that all samples were single phase with vaterite type structure. From IR and NMR spectra, it could be concluded that YBO3 contains mainly BO4 tetrahedra which is in favor for absorption VUV excitation. Monitoring by 598nm
emission, the main excitation peak at about 247nm was observed in the excitation spectrum of spherical Y0.95Eu0.05BO3. Correspondingly, under 247nm excitation, the main peak at about 598nm was observed. The photoluminescence intensity (5D0→7F1 transition of Eu3+) of spherical shape of Y0.95Eu0.05BO3 was 1.5 times in comparison with which prepared by solid-state reactions. The best photoluminescence intensity was obtained when the concentration of Eu3+ is at 20 at. %. It indicated that hydrothermal method have a potential in the preparing various particles phosphors for application in displays and lamps.
Influences of Severe Deformation and Alloy Modification on Secondary Hardening and Fracture Behavior
Authors: Sim Ho Sup , Lee K.S. , Lee Kon Bae , Yang Hyung Ryul , Kwon Hoon
Published: March 2009

Secondary hardening and fracture behavior in the high Co-Ni steels containing W, has been studied in terms of severe deformation, Cr addition, and austenite condition. Two kinds of Co- Ni steels, containing the only W(W steel), and the W and Cr(WCr steel), were severely rolled and followed by direct quenching(DQ). In comparison with undeformed specimens, reaustenitizing( RA) was performed. DQ specimens exhibited higher impact toughness as well as higher hardness, as compared to RA specimens. The aging kinetics of the WCr steel was
accelerated due to the Cr addition. While the W steel showed the intergranular embrittlement in the high temperature RA condition, in addition, the WCr steel exhibited the transgranular mode of mostly dimple type.
Orientation Distributions of Ferroelectric BLT Films for High-Density Semiconductor Memories
Authors: Seo B.I. , Park No Jin , Kim Sung Jin , Yang B. , Oh Y.H. , Hong Suk Kyoung
Published: March 2009

Issues of ferroelectric high-density memories (>64Mb) indispensable for upcoming ubiquitous era have been on the cell integration less than 0.1um2 and reliabilities. Thus nanoscale control of microstructures of ferroelectric films with large switching polarization has been one of the issues to obtain the uniform electrical properties for realization of high-density memories. In this study the grain orientations and distributions of BT-based films by spin-on coatings were examined
by an electron backscatter diffraction (EBSD) technique. Ferroelectric domain characteristics by a piezoresponse force microscope (PFM) were also performed to study the dependence of reliabilities on the grain orientations and distributions.
Molecular Organic White Light-Emitting Devices Fabricated by a Simple Way through Nondoped Process
Authors: Wu Zhi Jun , Jiang Wen Long , Chen Shu Fen , Zhao Yi , Hou Jingying , Liu Shi Yong
Published: March 2009

we designed and fabricated a white organic light-emitting device based on{[2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9yl)ethenyl]-4H-pyran-4-ylidene] propane-dinitrile}ultrathin layer and 4,4 ´ -bis(2,2 ˊ diphenylvinyl)-1,1 ˊ -biphenyl. It shows a maximum power efficiency of 1.8l m/W at 4 V (the brightness is 51 cd/m2). Its brightness reaches 8496 cd/m2 at 16 V. And the chromaticity coordinates varying from (0.42,0.34) to (0.32,0.28) with the forward bias from 4 to 16 V are well within the white region.
Synthesis of TiNi Particles in High Temperature Molten Salts
Authors: Yang Rui Song , Cui Li Shan , Zheng Yan Jun , Zhao Jin Long
Published: March 2009

. NiTi particles were prepared by the reaction between Ti and Ni powders in high temperature molten salts. Results of differential scanning calorimetry (DSC) confirmed the martensitic transformation of the prepared NiTi particles. Backscatter electron image of scanning electron microscopy (SEM) showed that the synthesized NiTi particles were captured by the molten salts, which revealed the mechanism of the chemical synthesis method in molten salts.