bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on Route Optimization of Dynamic Random Network Based on Genetic Algorithm
Authors: Zhang Chun Lei
Published: June 2010

The traditional algorithms of shortest path, different path and etc can only solve the path optimization problems of static network. Based on the fact of actual transport network as dynamic random network, the paper used method of shortest route to optimize the path. The solution of shortest route was on the basis of genetic algorithm. The paper designed operators of crossover, mutation and selection. In addition, the specific example of dynamic random network route selection based on the proposed algorithm also verified the feasibility of the algorithm.
Research on Simulation Platform Architecture for Noise Reduction of Electric Locomotive Wheel
Authors: Ma Si Qun , Zhao Wan Li , Li Ya Na , Huang Xue Fei , Wu Xiao Peng , Chen Xuan , Li Lin Feng , Kang Qing Hu
Published: June 2010

Wheel/rail rolling noise is the main source of noise from railway operations, it is at least
as important as aerodynamic noise. In this paper, the makeup of unit modules of CAE(Computer
Aided Engineering) simulation platform for of railway passenger car and its function frame are
given. Based on finite element method, boundary element method, the structural model, interior
acoustic cavity and acoustics model of electric locomotive wheel were analyzed by Nastran and
Sysnoise software. This paper is imposed sinusoidal excitation on the wheel, and then the laying of
the viscoelastic layer and optimization of damping-wheel, obtain the wheel’s structure of the
vibration noise radiation.The analysis result shows that the laying of the viscoelastic layer can
reduce wheels radiation noise, and the noise can be reduced from 0.27 to 8.62 dB.Practical
application indicated this simulation platform can supply effective technology support for the
development of product.
Research and Application of SOA-Based Simulation System Used in Hydropower Project
Authors: Meng De Yun , Wang Li , Hao Yi
Published: June 2010

In the field of hydropower project, the overabundance of information from multiplex data sources has forced managers and decision makers to spend much time dealing with information they need. Therefore the research on project simulation system is quite necessary. If system can provide some construction plan and schedule of the project properly, it will greatly improve the effectiveness of the plan. After the analysis of specific projects’ process and demands, this paper puts forward a visual simulation solution to large-scale hydropower construction, which including visual simulation model, design of algorithms and system implementation. Based on SOA structure, the optimization model and the simulation results’ 3D visualization are provided and a virtual three-dimensional world of the complicated coordinal construction process is proposed, with the advantage of direct viewing and real-time interactive, facilitating effective technical support for the decision of project construction design, and greatly enhancing the information level of design and organization of large-scale hydropower projects.
Impulsive Control of Permanent Magnet Synchronous Motors
Authors: Li Zhong Hua , Liu Yi
Published: June 2010

The permanent magnet synchronous motors (PMSMs) may have chaotic behaviors for the uncertain values of parameters or under certain working conditions, which threatens the secure and stable operation of motor-driven. Hence, it is important to study methods of controlling or suppressing chaos in PMSMs. In this letter, robust stabilities of PMSM with parameter uncertainties are investigated. A novel asymptotical stability criterion is established. Some illustrated examples are also given to show the effectiveness of our results.
Microstructure and Corrosion Behavior in Al-Mg Based Alloys Subjected to Continuous Cyclic Bending and Annealing
Authors: Takayama Yoshimasa , Kido Yuki , Kato Hajime , Watanabe Hideo
Published: June 2010

Coarsening of grain structure in surface layers in 5454 and 5083 Al-Mg based alloy sheets has been made by continuous cyclic bending (CCB), which is a useful straining technique to produce the high strain on the surface layers and the lower strain in the central layer of the sheet, and subsequent annealing. The microstructure on cross-section of the samples was analyzed by SEM/EBSD technique. For the samples before and after CCB/Annealing corrosion behaviors in NaCl or HCl solution were investigated. As a result, the samples subjected to CCB/Annealing showed higher corrosion resistance on coarse-grained surface layers. Less change in the corrosive solutions was observed on the grains parallel to {001} or {111} plane.
Effect of Zr Addition on Microstructure and Warm Formability of Al-Mg Sheet Alloys
Authors: Zhu Han Liang , Dargusch Matthew S.
Published: June 2010

The trace element Zr was added to an Al-Mg alloy to investigate its effects on microstructure and warm formability of aluminium sheets. Microstructural examination showed that the Zr addition resulted in an elongated grain structure due to inhibitedrecovery and recrystallization by Al3Zr particles during thermomechanical treatments. In order to evaluate the warm formability, warm tensile tests were carried out at temperatures ranging from 275 to 350°C, and at strain rates ranging from 0.015 to 1.5 s-1. The results showed that the addition of Zr increased the flow stress but decreased the ductility at most test conditions. At a low strain rate of 0.015 s-1, the addition of Zr resulted in low ductility at 350°C but high ductility at 275°C.The effect of Zr additions on warm formability is discussed on the basis of the microstructural changes.
Adiabatic Shear Banding in an Al-Mg-Si Alloy Processed by Equal Channel Angular Pressing
Authors: Vaseghi Majid , Taheri Ali Karimi , Yoo Ji Hoon , Joo Soo Hyun , Kim Hyoung Seop
Published: June 2010

Equal channel angular pressing is an outstanding method for imposing large plastic deformation to metallic materials without any decreasing in cross section area of as processed samples. In this paper, the effect of working temperature, ram speed and the number of passes on the formation of adiabatic shear bands in Al6061 during equal channel angular pressing was investigated. Billets of the alloy were processed up to four passes via route BC from room temperature to 200oC with two ram speeds using a die that imparts an effective strain of ~1.1 per pass. The results have demonstrated that the onset of the adiabatic shear banding in this alloy strongly depends on the ram speed: more frequently observed at the higher ram speed than the lower speed. Although the geometry of the macroscopic view of shear band is similar in all cases, the development of bands depends on the number of passes as well as processing temperature.
Nano-Scale Analysis of Nano-Bainite Formed in Advanced High Strength Steels
Authors: Timokhina Ilana B. , Beladi Hossein , Xiong Xiang Yuan , Pereloma Elena V. , Hodgson Peter
Published: June 2010

The effect of composition and processing schedule on the microstructure of C-Mn-Si-Mo-(Al)-(Nb) steels containing nano-bainite was studied using transmission electron microscopy (TEM) and atom probe tomography (APT). The major phase formed in all steels was nano-bainite. However, the steels with lower carbon and alloying addition content subjected to TMP had better mechanical properties than high alloyed steel after isothermal treatment. The presence of ferrite in the microstructure can improve not only ductility but lead to the formation of retained austenite with optimum chemical stability.
Local Atomic Arrangements of Pd-Based Bulk Metallic Glasses of the Metal-Metalloid Type Demonstrated by Molecular Dynamics Simulations
Authors: Takeuchi Akira , Inoue Akihisa
Published: June 2010

Molecular dynamics (MD) simulations based on a plastic crystal model (PCM) were performed for a Pd0.4Ni0.4P0.2 alloy in Metal-Metalloid (M-MLD) type of bulk metallic glass (BMG). Two kinds of clusters of cubeoctahedron capped with four half-octahedra and trigonal prism were used as initial atomic arrangements of the Pd0.4Ni0.4P0.2 alloy. Random rotations of clusters around their centers of gravity and subsequent structural relaxation vitrified the alloy. The high glass-forming ability of the Pd0.4Ni0.4P0.2 alloy is due to the critically-percolated, cluster-packed structure that is a universal feature for both M-MLD and M-M types of BMGs.
Microstructural Assessment of the Oxidation Behavior of Cu-Based Metallic Glass Powder
Authors: Yan Ming , Li Xiao Peng , Yu Peng , Schaffer Graham B. , Qian Ma
Published: June 2010

Gas-atomized Cu-based metallic glass powder was heat-treated in air from below its glass transition temperature (Tg) to well above its crystallization temperature (Tx). Severe oxidation occurred at temperatures > Tx while at temperatures < Tg oxidation was sluggish. The oxidation products were determined and the mechanism is discussed based on the microstructural findings.
Relaxation Behavior of Zr-Cu-Al Ternary Bulk Glassy Alloy Studied by Using Positron Annihilation Techniques
Authors: Ishii Akito , Mineno Shinya , Iwase Akihiro , Yokoyama Yoshihiko , Konno Toyohiko J. , Hori Fuminobu
Published: June 2010

Zr-based bulk glassy (BG) alloys show high tensile strength and a high Charpy impact value. In this study, the free volume changes for the hypoeutectic Zr60Cu30Al10 BG alloy during isothermal annealing below glass transition temperature (Tg) have been investigated by positron annihilation lifetime and coincidence Doppler broadening (CDB) measurements. The positron lifetime of hypoeutectic and eutectic BG alloys is almost the same, although the atomic volume ratio, estimated by the density for the eutectic BG alloy is different from that for the hypoeutectic BG alloy. The CDB spectra show a marked difference between eutectic and hypoeutectic BG alloys; that is, the spectrum of the hypoeutectic BG alloy is closes to that of Zr metal than that of the eutectic BG alloy. This result exhibits that the elemental fraction of Zr atoms around free volume in hypoeutectic BG alloy is greater than that in eutectic BG alloy. The CDB ratio profiles for the hypoeutectic BG alloy during annealing shows no appreciable change. The same trend was observed in the eutectic BG alloy.
Influence of Solidification Speed on Quality and Quantity of Structural Defects in Fe61Co10Zr2.5Hf2.5Y2W2B20 Amorphous Alloy
Authors: Nabiałek Marcin , Dośpiał Marcin , Szota Michał , Pietrusiewicz Paweł
Published: June 2010

The microstructure of Fe61Co10Zr2,5Hf2,5Nb2W2B20 amorphous alloy in the form of ribbons obtained by classical melt spinning and plates obtained by an induction suction method were investigated using X-ray diffraction. The type of structural defects were studied by analysis of the magnetization characteristics near ferromagnetic saturation of the sample. It was shown that the presence of structural defects is strongly correlated with sample thickness and production process. It was shown that ribbons with cooling rate between 105-106 K/s have point type defects, wires obtained with lower cooling rate between 101-102 K/s, have linear type defect (quasi-dislocation dipoles). crystallization.
FePBNbCr Soft Magnetic Glassy Alloys “SENNTIX” with Low Loss Characteristics for Commercial Inductor Cores
Authors: Matsumoto Hiroyuki , Urata Akiri , Yamada Yasunobu , Inoue Akihisa
Published: June 2010

The inductor for a power supply is expected to have higher efficiency and capability of dealing satisfactorily with large current. Additionally, high corrosion resistance characteristics are also required for commercial inductors in practical use of. Thereby, we focused on Fe-based glassy metal alloys with both high magnetization and low magnetic anisotropy ［1］, and developed the novel glassy metal alloys with a chemical composition Fe97-x-yPxByNb2Cr1. In this glassy metal alloy, 1 at % Cr is the optimum composition for the realization of higher corrosion resistance as well as a high magnetic flux density. The glassy Fe97-x-yPxByNb2Cr1 (x=5-13, y=7-15) alloy exhibits the high glass-forming ability leading to the large thickness of 110-150 μm and low coercive force of 2.5-3.1 A/m due to higher structural homogeneity in wide range of composition. The large critical thickness of this alloy should be caused by the high glass-forming ability (GFA) due to the existence of the super cooled liquid region (Tx) of roughly 30 K. Therefore a Fe77P7B13Nb2Cr1 powder/resin composite core displays a much lower core loss of 650 W/m3 than the conventional amorphous Fe75Si10B12Cr3 powder/resin composite core by approximately 1/3.
High Strength and High Ductility in Electrodeposited Nanocrystalline Ni–W Alloy
Authors: Kazutaka Fujita , Suidu Taiji , Yamasaki Tohru
Published: June 2010

The tensile specimen of nanocrystalline Ni–W alloys with 50 μm × 20 μm in area and 4 mm in gauge length was made by using an electrodeposit together with ultraviolet light lithographic technique. The composition and grain size were Ni-16.9 at.% W and about 6 nm, respectively. Tensile testing of the alloy was carried out. The nominal tensile strength and Young’s modulus were about 2.7 GPa and 123 GPa, respectively. The elastic strain and plastic strain were about 2 % and 1 %, respectively. The stress-strain curve showed work hardening. The macroscopic fracture part yielded necking and the microscopic fracture surface showed dimple pattern. As mentioned above, this electrodeposited nanocrystalline Ni-W alloy showed high strength, low elastic modulus and high ductility.
Study on Carbonitride Precipitating Process in Nb-V Micro-Alloyed Steel
Authors: Liu Wen Qing , Zhu Xiao Yong , Wang Xiao Jiao , Xiong Xiang Yuan
Published: June 2010

The carbonitrides precipitates in Nb-V micro-alloyed steels were investigated by 3DAP. Much difference in the composition and size of the precipitates were observed. It is proposed that the carbon atoms segregated first at the dislocation or vacancy, and the vanadium and niobium atoms diffused to these sites to form the V-C, V-Nb-C clusters, leading to the formation of (Nb,V)C complex phase. The composition becomes inhomogeneity as the precipitates grow up.
Synthesis and Characterization of CdSe Microspheres via Solvothermal Process
Authors: Yang Juan , Zang Chuang Liang , Cheng Xiao Nong
Published: June 2010

CdSe particles with the wurtzite structure have been synthesized via solvothermal method using a mixed solution of triethylenetetramine (TETA) and de-ionized water (DIW) without adding a reducing agent. It was found that the ball-like CdSe precursor with the zinc-blende phase could be transformed to the wurtzite structure after heat-treating at 580 °C in Ar atmosphere and the obtained microspheres were composed of small CdSe particles. The experimental results were compared with that obtained without TETA and it was speculated that TETA in the mixed solution played a role of reducing agent and solvent. Both the as-prepared products and the annealed powders were systematically characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared absorbance spectroscopy (FTIR).
Preparation and Characterization of BNC Compounds with Cylindrical and Bamboo Nanotubes
Authors: Zhu De Ming , Kisi Erich H.
Published: June 2010

BNC nanotubes were prepared by a high-energy ball milling and annealing method. Graphite carbon (C) and hexagonal boron nitride (h-BN) powder was first milled at room temperature to generate highly disordered nanoporous particles with a metastable structure. Upon elevated temperature annealing up to 1300 °C, these nanoporous particles were chemically and thermally activated to grow BNC nanotubes with both cylindrical and bamboo-like morphology. The cylindrical tubes have smaller diameters from 40 to 60 nm and lengths up to 2 μm. The bamboo tubes have larger diameters from 80 to 150 nm and lengths up to 10 μm. The formation mechanisms of different nanostructures are discussed.
Mechanical Properties of Electrodeposited Ni-SiO2 Nanocomposite
Authors: Miyamoto Hiroyuki , Ueda Koushirou , Uenoya Toshiyuki
Published: June 2010

Nanocomposite materials consisting of a nanocrystalline Ni matrix with grain size ranging from 23 to 40 nm, and nano-size SiO2 particles with average particle size of 7 nm, have been produced by pulse electrodeposition. Grain size was controlled by peak current density. It was observed that SiO2 particles precipitated within grain interior by the transmission electron microscopy (TEM). Hardness and tensile strength of nanocomposites with a grain size larger than 35 nm was higher than that of nanocrystalline pure Ni possibly as a consequence of Orowan precipitation hardening. However, hardness of Ni-SiO2 nanocomposites with a grain size smaller than 30 nm was the same as that of nanocrystalline pure Ni. It was considered that the SiO2 particles do not contribute to hardening because deformation occurs by a grain-boundary-mediated mechanism such as grain-boundary sliding.
Modelling the Crystallization Reactions of Amorphous Precursors in Fe3B/Nd2Fe14B Nanocomposite Magnets
Authors: Ly Vanalysa , Gorsse Stéphane , Suzuki Kiyonori , Hutchinson Christopher R.
Published: June 2010

A physically-based model is proposed for the competitive precipitation of multiple phases (bcc-Fe, Fe3B, Nd2Fe14B, Nd2Fe23B3, NdFe4B4 and Fe2B) from an amorphous Fe-B-Nd matrix. These materials form the basis of a class of nanocomposite hard magnets. The nucleation and growth of the different phases are calculated using computational thermodynamics and kinetics tools with input from a thermodynamic assessment of this system. In some alloy compositions, the phase formation sequence during crystallization shows significant sensitivity to the heating-rate. Model calculations illustrate that this effect cannot be explained by homogeneous nucleation and growth of the phases. The possible role of heterogeneous nucleation is briefly discussed.
Effect of Organic Capping on the Magnetic Properties of Au Nanoparticles
Authors: Zhang H. , Suzuki Kiyonori , Saito K. , Garitaonandia J.S. , Goikolea E. , Insausti M.
Published: June 2010

The magnetic and optical properties of regioregular poly(3-hexylthiophene)-capped Au nanoparticles (NPs) have been investigated in order to clarify the effectiveness of polythiophene capping on the induction of ferromagnetism in Au. The room-temperature magnetization curve of the polythiophene-capped Au NPs exhibits a clear hysteresis behavior with a spontaneous magnetization of 8.5 x 10-3 emu/g. The average magnetic moment of the surface Au atoms is estimated to be 2.6 x 10-3 B. The ultraviolet-visible spectrum shows a clear sign of the surface plasmon absorbance of metallic Au which reflects the week character of the chemical bond between the Au and S atoms on capping surface. Our results show clearly that Au NPs capped with polythiophene can be ferromagnetic.
The Electrical Characterization of Single ZnO Nanowries Field-Effect Transistors
Authors: Li Hui Feng , Huang Yun Hua , Xing Xiu Jun , Su Jia , Zhang Yue
Published: June 2010

The electrical properties of single ZnO nanowire were researched in the chamber of a scanning electron microscope under high-vacuum conditions using nanomanipulator and measurement system. The result shows that ZnO nanowire resistivity was about 1.4 Ω•cm with Ohmic contact. The local change of electron density induced by Shottky contacts or Ohmic contact with tip and semiconductor/metal materials significantly affects the current transport through the nanowire. Single ZnO nanowire was configured as field effect transistors (FET) and based on metal tantalum (Ta) as electrodes show a pronounced n-type gate modulation with an electron concentration of ~1.0×1019 cm−3 and an electron mobility of ~52 cm2 /V s at a bias voltage of 1 V.
The Influence of Processing Conditions on Hardness Homogeneity Evolution in Commercially Pure Cast Aluminium Processed by ECAP
Authors: Lathabai Sri , Vargas Margarita , Larroque Matthieu , Urbani Claude
Published: June 2010

Commercially pure cast aluminium was subjected to equal channel angular pressing (ECAP) at room temperature using routes A, Bc and C. Microhardness distribution maps were produced on sections of extruded billets after one, two, three and four passes for each of the processing routes. It was found that the mean hardness increased significantly already after the first pass. With subsequent passes, the hardness increase was smaller but the hardness distribution became narrower, indicating increasing homogeneity. For route Bc, a slight decrease in average hardness was observed after the fourth pass. The mean hardness after four passes was highest for the route C sample, followed by the route A and route Bc samples.
Grain Refinement and Texture Evolution during Equal Channel Angular Extrusion of Pure Cu and Cu-Zn Alloys
Authors: Chen Hai Hong , Li Sai Yi , Zhang Dong Hong , Huang Xin
Published: June 2010

Equal channel angular extrusion (ECAE) experiments were conducted on as-cast pure Cu, Cu–10%Zn, and Cu–30%Zn, using a 90 die for up to 4 passes. The stacking fault energies (SFEs) of the three materials decrease with increasing Zn content. The microstructures and textures of the processed billets were analyzed using optical microscope and X-ray diffraction, respectively. The results show that the structures of the three materials were all significantly refined after ECAE and a lower SFE led to a finer microstructure with a higher density of shear bands. The textures were considerably weakened after 4 passes, more apparent in the material with a lower SFE. It is concluded that the SFE has significant influences on both the grain refinement and texture evolution during ECAE deformation.
Enhancing Ductility of ECAP Processed Metals
Authors: Llorca-Isern Nuria , Grosdidier Thierry , Cabrera Jose María
Published: June 2010

Mechanical properties such as hardness, mechanical strength or fatigue resistance are by far the most successful material behaviour improved by the ECAP processed. However, the lack of ductility is the most critical negative effect. Combination of multimodal grain size is one of the most promising solutions to improve the strength/ductility balance. Different characterisation techniques are used here to analyse the properties of ECAP Cu thermal treatments and their mechanical properties influence were also investigated.
Ultrafine Grained Structure Formation in Low Carbon Steel Processed by SPD
Authors: Zrník Jozef , Dobatkin Sergey V. , Raab George , Kraus Libor
Published: June 2010

The present work deals with grain refinement in low carbon steel (AISI 1010) by severe plastic deformation (SPD). The effect of structure modification was evaluated with respect to thermomechanical (TM) treatment of steel prior to SPD. The grain refinement was accomplished during warm angular channel pressing (ECAP) at 300°C. The evolution of microstructure during equal channel angular pressing (ECAP) was studied using SEM and TEM of thin foils. Ultrafine-grained structure development is described in relation to strainintroduced. At lower strain applied, the subgrain and/or polygonized structure was frequently found. Due to increased deformation temperature, the dynamic recovery contributed to structure refinement in both structural states. The amount of high angle boundaries increased with higher ECAP strain and was higher in TM-processed steel. There was only an indistinctive difference in structure refinement, considering different initial structures of the steel.The deformation behaviour of UFG steel in dependence on processing conditions was evaluated by a tensile test and correlated with structural characteristics.
High Strength and Ductility in Ball-Milled Titanium Powders Consolidated by High-Pressure Torsion
Authors: Edalati Kaveh , Horita Z. , Hiroshi Fujiwara , Ameyama Kei , Tanaka Masaki , Higashida Kenji
Published: June 2010

Pure Ti powders were subjected to ball milling and subsequently high-pressure torsion (HPT) for consolidation. It is found that a fully dense (99.9%) disc with ultrafine grained structure (~50-300 nm) was produced. The strength and ductility were well comparable to those of ball-milled Ti-6%Al-4%V powders after hot roll sintering.
Aging Behavior of Al-Li-Cu-Mg Alloy Processed by High-Pressure Torsion
Authors: Lee Seungwon , Akama Daichi , Horita Z. , Masuda Tetsuya , Shoichi Hirosawa , Matsuda Kenji
Published: June 2010

This study presents an application of high-pressure torsion (HPT) to an Al-Li-Cu-Mg alloy (2091). The alloy was subjected to solid solution treatment at 505oC for 30 minutes and was processed by HPT under 6 GPa for 5 revolutions at room temperature. The hardness increased with straining and saturated to a constant level at 225 Hv. Aging was undertaken on the HPT-processed alloy at 100, 150 and 190oC for the total periods up to 9.3 days. The aging treatment led to a further increase in the hardness to ~275 Hv. It is shown that the simultaneous strengthening of the alloy due to grain refinement and age hardening was successfully achieved by application of HPT and subsequent aging treatment. The enhancement of the strength is prominent when compared with the application of a conventional rolling process.
Structure and Mechanical Properties of Asymmetrically Rolled IF Steel Sheet
Authors: Orlov Dmitry , Lapovok Rimma , Tóth László S. , Timokhina Ilana B. , Hodgson Peter , Bhattacharjee Debashish , Haldar Arunansu
Published: June 2010

As-received hot-rolled 5.6 mm thick IF steel sheet was symmetrically/asymmetrically cold rolled at room temperature down to 1.9 mm. The asymmetric rolling was carried out in monotonic (an idle roll is always on the same side of the sheet) and reversal (the sheet was turned 180º around the rolling direction between passes) modes. Microstructure, texture and mechanical properties were analysed. The observed differences in structure and mechanical properties were modest, and therefore further investigation of the effects of other kinds of asymmetry is suggested.
Steel-Magnesium Composite Wire Obtained by Repeated Co-Extrusion
Authors: Bouaziz Olivier , Sauvage Xavier , Barcelo D.
Published: June 2010

A composite wire combining steel and magnesium has been prepared co-extrusion. Both the microstructures and the mechanical properties were characterized showing the opportunity for the development of original lightweight multi-metallic composites with strength and ductility.
Dynamic Recrystallization Behaviour in Cu-Sn-P Alloy for High Strength Copper Tube
Authors: Watanabe Masato , Shirai Takashi , Ishibashi Akihiko , Miura Hiromi
Published: June 2010

Dynamic recrystallization (DRX) behaviour in a newly developed Cu-Sn-P alloy for heat exchangers and tubes was systematically investigated. For this purpose, Cu-Sn-P alloys with different content of Sn were deformed in compression at temperatures between 1073 K and 1213 K and at various strain rates from 2 x 10-4 s-1 to 2 x 10-1 s-1. The onset of DRX was more advanced with increasing temperature and with decreasing strain rate. Full DRX was not achieved at the testing conditions of lower temperature and higher strain rate even after straining to ε = 1.0. This tendency was more significant in the alloy with higher Sn content. With increasing Sn content, the flow stress and the obtained grains size became higher and finer, respectively. These experimental results indicate the important role of Sn for strengthening and microstructual control.
Dynamic Recrystallization Behavior of Biomedical CCM Alloys in Hot Compression Process
Authors: Li Yun Ping , Kurosu Shingo , Onodera Emi , Matsumoto Hiroaki , Chiba Akihiko
Published: June 2010

Dynamic recrystallization behavior of Co-29Cr-6Mo-0.16N alloy was analyzed in details. Compression tests were carried out in a computer aided Thermecmaster- Z hot forging simulator. The results showed that uniformly distributed superfine grain size could be obtained by continuous dynamic recrystallization (DRX) process; Texture-free microstructure with uniformly distributed equiaxed fine grains was obtained. The formation of profuse stacking faults and their subsequent intersections are considered to be the principle mechanisms of DRX.
Evaluation of Plastic Work Density, Strain Energy and Slip Multiplication Intensity at Some Typical Grain Boundary Triple Junctions
Authors: Ohashi Tetsuya , Sato Michihiro , Shimazu Yuhki
Published: June 2010

Plastic slip deformations of tricrystals with simplified geometries are numerically analyzed by a FEA-based crystal plasticity code. Accumulation of geometrically necessary (GN) dislocations, distributions of the total slip, plastic work density and GN dislocations on slip systems, as well as some indices for the intensity of slip multiplication are evaluated. Results show that coexistence of GN dislocations on different slip systems is prominent at triple junctions of grain boundaries.
Precipitates Behavior during Thermomechanical Processing of Low Mn, Ti Added Pipeline Steels
Authors: Dehghan-Manshadi Ali , Dippenaar Rian J.
Published: June 2010

The behavior of different precipitates during hot deformation of a low carbon, low manganese, and titanium added steel has been studied. Microstructural and inclusion analyses from the centerline of as-cast slabs revealed the presence of a wide variety of simple and/or complex precipitates with different size and morphologies. These precipitates were mostly deformed along the deformation direction and affected the recrystallization as well as the mechanical properties of the material. However, those effects altered by changing the re-heating temperature and/or deformation rate.
Simultaneous Enhancement of Electrical Conductivities and Mechanical Properties in Cu-Ti Alloy by Hydrogenation Process
Authors: Kamegawa Atsunori , Iwaki Toru , Okada Masuo
Published: June 2010

Effects of hydrogenation process of the microstructure, electrical conductivity and mechanical properties for the Cu-(1~3) mass%Ti alloys were investigated. During hydrogenation process at 350°C, 7.5 MPa for 48 h, the disproportionation reaction occurred with forming of Ti hydrides in the alloy. It is found that remarkable simultaneous improvements of mechanical strength of 1094 MPa and electrical properties of 21%IACS are obtained in the hydrogenated Cu-3mass%Ti alloy.
Cold Joining of Dissimilar Metal Sheets by Shot Peening
Authors: Harada Yasunori
Published: June 2010

The cold joining of dissimilar metal sheets using a shot peening process was investigated. In shot peening the substrate undergoes large plastic deformation near the surface due to the hit with shots. Consequently, plastic flow areas formed by cold working may form the surface layer. The dissimilar sheets with the concavo-convex edge are connected, and then the contact area is shot-peened. In this joining, the convex edges of the sheet are laid on the other sheet. Namely, in the joining area, the two sheets are superimposed. In the experiment, the shot peening treatment was performed by using an air-type peening machine. The shots used were made of high carbon cast steel. Air pressure was 0.6MPa and peening time was in the range of 30-150s. The peening conditions were controlled in the experiment. The sheets were commercial low-carbon steel, stainless steel, pure aluminum, pure titanium, pure copper, and magnesium alloy. The effects of processing conditions on the joinability were mainly examined. The joint strength increased with the kinetic energy of shots. It was found that the present method was effective for cold joining of dissimilar metal sheets.
The Contribution of Diffusion Coefficient to the Eutectic Instability and Amorphous Phase Formation
Authors: Wang Nan , Wang Xiao , Yao Wen Jing
Published: June 2010

The diffusion coefficient D decides the diffusion length of solute boundary and plays a key role in the microstructure selection. This paper examines quantitatively the contribution of diffusion coefficient to the eutectic instability and amorphorization ability. The maximum growth velocity Vmax and the maximum undercooling Tmax as functions of activation energy Q in strong liquids are deduced theoretically based on eutectic growth model by separating Q from D. It reveals that the larger the Q, the smaller the Tmax and Vmax, which shows the same tendency as experimental values in some Al-based alloys and glass formers. This indicates that it is the sluggish movement of atoms that makes the transition from eutectic to others structural morphologies, even to amorphous phase, occur at smaller interface growth velocity or undercooling, which is the main contribution of the diffusion coefficient to the amorphorization ability.
Modelling and Experiments Concerning Dendrite Re-Melting and Its Role in Microstructural Evolution in Spray Formed Ni Superalloys
Authors: Zhang Yong , Guo Z. , Zhang Guo Qing , Mi Jia Wei , Grant Patrick S.
Published: June 2010

This paper presents a combined experimental and modelling approach to understand dendrite fragmentation of atomised metal alloy droplets during deposition in spray forming, and to study quantitatively the relationship between this dendrite fragmentation behavior and subsequent microstructural evolution. A Gleeble 3500 physical simulator was used to create controlled thermal shock conditions in solid-liquid mixtures of Ni superalloy IN718 atomised powders, which simulated the environment of droplet deposition during the twin-atomiser spray forming of large diameter IN718 alloy billets at BIAM. The experiments were complemented by phase field modelling studies at Oxford. Experiment and modelling supported the hypothesis that the characteristic equiaxed spray formed microstructure depends critically upon the rapid remelting and thermal shock of fine-scale dendrites in solid particles in the spray to provide a high density of embryonic grains.
Solidification Mechanisms in the Sn-Cu-Ni Lead-Free Solder System
Authors: Ventura Tina , Cho Young Hee , Dahle Arne K.
Published: June 2010

Pb-free solders based on near-eutectic Sn-0.7Cu-xNi alloys provide excellent solderability during wave soldering with cost advantages compared to Ag-containing alternatives. However, there is only limited knowledge of the solidification mechanisms in this alloy system and, furthermore, the ternary Sn-Cu-Ni phase diagram is not yet fully established. In this study, unidirectional solidification has been conducted in a Bridgman furnace using both binary alloys from the Sn-Cu6Sn5 system and ternary Sn-rich Sn-Cu-Ni alloys. The influence of Ni additions on the solidification mechanisms is assessed by comparing the microstructures of the ternary and binary alloys. The results are used to discuss the contrasting Sn-Cu-Ni phase diagrams reported in the literature. The results demonstrate the complex phase relations in the Sn-Cu alloy system, and the important role of trace amounts of various solute elements.
Semisolid Sinter-Forging of Hyper-Eutectic Al-Si Alloy Using Rapid Resistance Heating
Authors: Maki Seijiro , Noda Masayuki , Nakanishi Eitoku
Published: June 2010

In casting of hyper-eutectic Al-Si alloys, primary Si grains often grow, which deteriorates mechanical properties of the castings. In this study, an attempt was made to obtain hyper-eutectic Al-Si alloy parts without coarse primary Si grains by taking another route of sinter-forging. The sinter-forging taken up here is semisolid one. In this sinter-forging, a green compact billet of hyper-eutectic Al-25mass% Si alloy powder is rapidly resistance-heated into a semisolid state to promote the sintering and then upset-forged into a disc shape, and the performance was examined by paying special attention to the behavior of primary Si grains in the relation to the resistance heating condition.
Mechanical Properties and Microstructure of Aluminum Alloy Al-6061 Obtained by the Liquid Forging Process
Authors: Su Chun Wei , Oon Peng Hooi , Bai Y.H. , Jarfors Anders W.E.
Published: June 2010

The liquid forging process has the flexibilities of casting in forming intricate profiles and features while imparting the liquid forged components with superior mechanical strength compared to similar components obtained via casting. Additionally, liquid forging requires significantly lower machine loads compared to solid forming processes. Currently, components that are formed by liquid forging are usually casting alloys of aluminum. This paper investigates the suitability of liquid forging a wrought aluminum alloy Al-6061 and the mechanical properties after forming. The proper handling of the Al-6061 alloy in its molten state is important in minimizing oxidation of its alloying elements. By maintaining the correct alloying composition of Al-6061 after liquid forging, these Al-6061 samples can subsequently undergo a suitable heat treatment process to significantly improve their yield strengths. Results show that the yield strengths of these liquid forged Al-6061 samples can be increased from about 90MPa, when they are in the as-liquid forged state, to about 275MPa after heat treatment. This improved yield strength is comparable to that of Al-6061 samples obtained by solid forming processes. As such, the liquid forging process here has been shown to be capable of forming wrought aluminum alloy components that has the potential for structural applications.
Microstructure and Mechanical Properties of a Friction Stir Processed Al-Zn-Mg-Cu Alloy
Authors: Vargas Margarita , Lathabai Sri
Published: June 2010

Friction stir processing (FSP) was performed on AA 7075-T6, a heat treatable high strength Al-Zn-Mg-Cu alloy. The two main FSP parameters, the tool rotational and travel speed, were varied systematically in order to understand their influence on the microstructure and mechanical properties of the processed zone. At a given rotational speed, increasing the travel speed increased the microhardness of the nugget (stir) zone; for a given travel speed there appeared to be an optimum rotational speed which resulted in the highest microhardness. The range of FSP parameters used did not significantly influence the nugget zone grain size. It is suggested that the observed mechanical properties are a result of the complex interactions between the FSP thermo-mechanical effects and the processes of dissolution, coarsening and re-precipitation of the strengthening precipitates in this alloy.
Fabrication of Porous Metals with Directional Pores through Unidirectional Solidification of Gas-Dissolved Melt
Authors: Nakajima Hideo
Published: June 2010

Lotus-type porous metals with long cylindrical pores aligned in one direction are fabricated by unidirectional solidification through thermal decomposition method (TDM). The pores are evolved from insoluble gas when the molten metal dissolving the gas is solidified. In the conventional pressurized gas method, hydrogen pressurized in a high-pressure chamber is used to dissolve hydrogen in the melt. However, the use of high-pressure hydrogen is not desirable because of its inflammability and explosive nature. This is particularly true when scaling up to mass production of lotus/Gasar metals. In order to overcome this shortcoming, the thermal decomposition method was developed. Gas-forming compounds such as hydrides were added into the molten metal to fabricate lotus/Gasar metals. The porosity and pore size were controlled by the amount of gas-forming compounds, solidification rate, atmospheric pressure, etc. TDM method is applied to fabricate lotus copper, aluminium and iron.
Production Magnesium Alloy Strip with Boss and Rib Section by Melt Drag Process and Experimental Conditions
Authors: Nishida Shinichi , Fukudome Kazuki , Kudo J. , Motomura M.
Published: June 2010

This study aims to produce magnesium alloy strip with boss and rib directly from molten metal. Magnesium alloy is the lightest structural material, so it is expected to widely use for small electronic device and etc. We studied about melt drag process. Melt drag process is one of single roll strip casting process. We use model melt drag experimental device to produce rapid solidified magnesium strip with boss and rib. Substrate is used on model experimental device instead of roll to easily research shape of substrate. Diameter of boss is 5 mm, 7.5 mm and 10 mm. Height of boss is 6 mm. We revealed on this study that the experimental conditions to get good shape boss and rib, improvement substrate shape for good boss and rib, microstructure and etc.
Numerical Characterization of Anisotropic Heat Sink Composites
Authors: Fiedler Thomas , Murch Graeme E. , Bernthaler Timo , Belova Irina V.
Published: June 2010

This work addresses the numerical analysis of anisotropic composite structures for thermal energy storage and temperature stabilization. The basic idea of heat sink composites is the combination of metallic matrices for fast energy transfer with phase change materials for thermal energy storage. Anisotropic matrices, such as lotus-type structures, allow for increased control of the thermal energy flow, without the necessity of additional thermal insulation. As an example, thermal energy can be directed towards a surface cooled by convection and excess energy is stored in the phase-change material. Computed tomography data of copper lotus-type material is used for the generation of the numerical calculation models. Due to its particular meso-structure, this material is characterised by strongly anisotropic properties. The void space of this cellular metal is filled with the phase-change material paraffin in order to enhance the energy storage capacity. A recently extended Lattice Monte Carlo method is used to evaluate the anisotropic thermal properties of these promising materials.
Modeling Study of the Influence of Subflux Controller of Turbulence on the Molten Steel Flow in Tundish
Authors: Merder Tomasz
Published: June 2010

The objective of the study is to diagnose the current condition of the two-strand tundish. The investigated object is a “T”-type tundish. The nominal capacity of the tundish is 7.5 tonne of liquid steel. By the mathematical simulation, fluid flow and heat transfer of molten-steel in a tundish of a billet caster under different conditions (bare tundish and tundish with flow control device) are analyzed. Three variants of subflux controller of turbulence configurations in the tundish are tested. Numerical simulations of are carried out with the finite-volume commercial code FLUENT using the realizable k- turbulence model. Liquid steel velocity, temperature, turbulent kinetic energy and Residence Time Distribution (RTD) characteristic have been obtained as a result of mathematical calculations. The RTD curve is used to estimate the different volumes such as plug volume, dead volume and mixed volume inside the tundish. The ratio of mixed to dead volume, which indicates the mixing capability of a tundish, is estimated.
Optimum Pass Design of Bar Rolling for Producing Bulk Ultrafine-Grained Steel by Numerical Simulation
Authors: Inoue Tadanobu
Published: June 2010

The groove design for creating ultrafine-grained low-carbon steel through a caliber rolling process was studied from the viewpoint of the large strain accumulation and cross-sectional shape variation in a bar. A three-dimensional finite element analysis was employed for this purpose. The caliber rolling process of foval (flat-like-oval)/square type was proposed as a method to efficiently introduce a large strain in material. The relationship among the foval configuration, strain, and cross-sectional shape was examined in the caliber rolling. The influence of the equivalent strain distribution by 1st pass (foval rolling) depends strongly on the strain distribution and a cross-sectional shape by 2nd pass, and the foval configuration to accumulate a large strain efficiently was shown. The optimum pass schedule to fabricate a 13mm square bar of ultrafine-grained steel from a 24 mm square bar by caliber rolling at warm working temperatures was proposed.
Numerical Simulation of Deformation during Hot Procedure for Large Hydraulic Turbine Runner Blade
Authors: Wang Pei , Xiao Na Min , Li Dian Zhong , Li Yi Yi
Published: June 2010

Francis hydraulic turbine runner blade has a complex profile, which always causes severe and unpredictable deformation during the hot procedure. In this paper, an integral finite element method model based on ProCast software was developed to simulate the deformation of the blade during the whole hot procedure including casting, shake-out, cutting-off the gating system and heat treatment. And the model predictions were validated by the experimental measurements. Based on the predictions some inverse displacements were added to the initial mould. Finally a huge hydraulic turbine runner blade with uniform and reasonable machining allowance was produced successfully.
Effect of Micro-Elasticity on Grain Growth and Texture Evolution: A Phase Field Study
Authors: Kim Dong Uk , Kim Seong Gyoon , Kim Won Tae , Cho Jae Hyung , Han Heung Nam , Cha Pil Ryung
Published: June 2010

In this presentation, a novel phase field grain growth model combined with a micro-elasticity effect including elastic anisotropy and inhomogeity is presented to demonstrate the effect of micro-elasticity on grain growth and texture evolution. We report on texture evolution and abnormal grain growth induced by external elastic load from the viewpoint of micro-elasticity and first demonstrate that the previous mechanism (macroscopic viewpoint) on the effect of external elastic load on grain growth does not work in strain-controlled system. In contrast to the macro-elastic descriptions, strong localization of strain energy density and inhomogeneous distribution even inside grains are observed. Moreover, elastically soft grains with a higher strain energy density grow at the expense of the elastically hard grains to reduce the total strain energy. It is observed that strong <100>//ND fiber texture was developed in poly-crystalline Cu with initial random texture by biaxial external strain while <111>//ND fiber texture evolved in biaxial external stress condition. Even, grain growth of <100>//ND textured grains is occurred as abnormal grain growth when <100>//ND textured grains are surrounded by <111>//ND fiber textured grains.
Advanced Material-Technological Modelling of Complex Dynamic Thermomechanical Processes
Authors: Mašek Bohuslav , Jirková Hana , Malina Jiří , Jeníček Štěpán
Published: June 2010

Material-technological modelling has made great progress over recent years, thanks to the new possibilities opened up by developments in sensor technology, and especially in new methods of control, supported by innovative electronic elements and electronic circuits. One such device, developed for material-technological modelling, is the thermomechanical simulator which was established in the laboratories of the Research Centre of Forming Technologies FORTECH, in Pilsen, in the Czech Republic. Thanks to new knowledge and technical equipment the majority of technological processes or even technological chains can be modelled. The most considerable and most important innovation in the material-technological modelling process is the significant acceleration and increased precision of the modelling process. The present technology even allows modelling of highly dynamic processes, such as wire rolling including all thermodynamical effects. This paper presents the broad possibilities of the most modern material-technological modelling. The process of detecting technical and manufacturing problems during rolling and the possibilities of failure elimination are introduced in a practical example.
Crystal Plasticity Finite Element Modelling of the Influence of Friction on Surface Roughening during Uniaxial Planar Compression
Authors: Li Hei Jie , Jiang Zheng Yi , Wei Dong Bin , Han Jing Tao , Tieu A. Kiet
Published: June 2010

The friction is a key factor that influences the surface quality in metal forming. To figure out the relationship between the friction and the surface roughening, a finite element model is employed in the commercial finite element software ABAQUS to simulate the surface roughness of top side of Al plate during uniaxial planar compression. With the change of friction conditions, the surface roughening varies. The average surface roughness (Ra) shows a relationship with the friction coefficient. During the surface roughening process, the grain slip takes place in the “soft orientation”, and the “hard orientations” become the barrier of the slip.