bluuebunny/crossref_metadata_2025 huggingface dataset:
A Multi-Channel Radar Signal Process System
Authors: Xu Cheng Fa , Wang Jun Ling , Wu Rong Gang
Published: January 2010

In order to meet multi-channel, high data rate, intensive computing capacity of modern radar signal processing, a standard, scalable, high-performance general-purpose radar signal processing system platform is proposed. The main processor of this system platform is the DSP and FPGA. In the analysis of different kinds of radar signal processing algorithm, and taking into account the respective advantages and disadvantages of DSP and FPGA, In this paper, a software architecture method for radar signal processing is given to decide how to distribute different algorithm into DSP and FPGA. At last, for a certain type of circular array radar, an implementation of radar signal processing by using the general-purpose radar signal processing system platform is proposed.
Line-Based Optimization for 3D Object Reconstruction from Single Line Drawings
Authors: Chu Jun , Gao Man Tun , Zhang Gui Mei , Feng Rui Na
Published: January 2010

Based on iterative technique, a novel optimization approach for reconstruction a planar object from a perspective line drawing is proposed. Some constraint relationships between edges of a planar object are deduced and formulated as a linear system. The planar object can be recovered by solving the linear system. If the line drawing is a practical line drawing, the recovered planar object will be re-projected onto the projective plane. And then the parameters of the projection will be weighed with those of the corresponding line in original line drawing. The new linear system can be achieved by substituting the weighted parameters into the original linear system and solved again. This procedure is iterated until the value of an object function is smaller than the threshold predefined. Experiment results show that in addition to the ideal line drawing, the proposed algorithm can be applied to the practical line drawing.
Multi-Disciplinary Knowledge Integration in Aero-Engine Design
Authors: Chen Ze Feng , Yang Hai Cheng , Mo Rong , Sun Hui Bin
Published: January 2010

This paper studies multi-disciplinary knowledge integration technologies for aero-engine design process. The characteristics of the multi-disciplinary knowledge in aero-engine design process and the integration patterns between tacit knowledge and explicit knowledge are analyzed. A hierarchy model of aero-engine multi-disciplinary knowledge integration is proposed, and the key technologies are discussed briefly.
Hierarchy Evolutionary Searching Algorithm for DNA Encoding Sequence
Authors: Ye Lian , Chen Jing , Xing Yong Kang
Published: January 2010

DNA sequence design is the basic and important step for DNA computing. Good codeword could avoid some error may possibly occurred in practical computing. Therefore, much work has focused on designing the DNA sequences to make the molecular computation more reliable. In this paper, a new hierarchy evolutionary searching algorithm is proposed to obtain good DNA encoding sequences, this approach is based on combinatorial constraints which affect the molecular reaction process, and can provide some reliable and effective encoding sequences for controllable DNA computing.
On the Stability Problem of Multimedia Systems
Authors: Zhao Jie Min
Published: January 2010

An instability result of multimedia Systems is given by means of the analysis and computing method.
QoS Prediction Approach for Web Service Recommendation
Authors: Chen Zu Qin , Ge Ji Ke
Published: January 2010

This paper proposes a QoS prediction approach used to recommend web service to solve the problem of choosing high quality web service. This approach bases on other users’ experience. According to the different feeling of different user to the same service, and the different similarity among the QoS of different services, the approach first divides the users and services into several modes, and then computes the means of one mode to predict the QoS of a service that the user never used before. Experiment simulation show that the approach is operable to some extent.
Corrosion Behavior of a New Developed Ferritic Stainless Steels Used in Automobile Exhaust System
Authors: Chen C. , Shang Cheng Jia , Weng J.Y. , Li Dong Yang
Published: January 2010

The inside corrosion of failed automotive mufflers collected in China was investigated and the composition of the automotive exhaust gas condensate collected from HONGQI automobile was analyzed. According to the analyzed result of collected condensate’s composition, the corrosion resistance of a new designed high Cr stainless steel (B439M) bearing Nb and Ti and a low Cr T409L stainless steel were studied with a condensate corrosion test method which simulates the inside corrosion of automotive mufflers. The life of the two materials was estimated by extreme value analysis of the maximum corrosion depth obtained by the dip dry test (DDT). The life of type B439M steel was 1.6 times as long as that of type T409L steel. To clarify the corrosive process of the simulated condensate test, the electron work function (EWF) on the two stainless steels’ surface was evaluated. It was demonstrated that the surface of new designed stainless steel exhibited markedly improved resistances to corrosion during a simulated condensate test cycle and the corrosive process of simulated condensate test was evaluated and discussed.
In Situ Synthesis and Wear Resistance of Titanium Matrix Composites
Authors: Choi Bong Jae , Hong Kyung Eui , Youn Jeong Il , Kim Young Jig
Published: January 2010

The main purpose of this research is to evaluate the wear resistance of titanium matrix composites (TMCs). Reinforcements, TiB and TiC, were formed by in-situ reaction between boron carbide and commercial pure titanium. The confirmation of the sound synthesis of TMCs was done by phase identification. And then, sliding wear test were carried out to verify the wear resistance of TMCs by means of the coefficient of friction, wear loss and morphology wear track. The results of wear test indicate that TMCs have superior resistance than AISI H13 tool steel at the condition of severe loads.
Fluidized Bed Plasmas Reactor for Catalyst Synthesis and Pretreatment. Application for Pollution Abatement in Stationary and Mobile Sources
Authors: Foix Marjorie , Guyon Cédric , Tatoulian Michael , Da Costa Patrick
Published: January 2010

The preparation of automotive catalysts and commercial oxidation catalysts in stationary sources use a large amount of noble metal precursors. Moreover, during their preparation high energy (gas and temperature) is necessary for treatment processes. In order to develop a higher sustainable process, the plasma-assisted catalysts synthesis could be a solution. The use of plasmas for catalysis is already well developed and plasma treatment was already used in a low pressure system to replace the thermal calcination steps of the catalysts. Fluidized bed reactors offer the possibility to lead to homogenous treatment and have the additional advantage of excellent heat transfer rates between the gas and the particles, so that it can modify the catalytic properties of the prepared materials. The aim of our work is to prepare plasma-assisted catalysts dedicated to pollution abatement in stationary or mobile sources. For stationary sources, the first prepared catalysts are palladium based catalysts, which were chosen since the main reducing agent in combine heat power is methane. In the case of mobile sources, we have worked with silver based catalysts since ethanol could be chosen as a sustainable alternative reducing agent to replace ammonia. After the preparation of the different catalysts, the low fluidized bed plasma reactor was used to modify Pd/ γ-alumina and Ag/γ-alumina catalysts. A comparison with “classical calcination” in air at 500°C was performed in order to show the advantages of plasma treatments. The first catalytic results show that plasma treated catalysts lead to higher pollutant abatement than classically prepared ones. Thus, concerning the plasma process, we have studied the role of the plasma treatment time as well as the nature of the gas treatment. The characterization of the catalysts is in course in order to understand the influence of plasma treatment parameters on catalytic results.
An Enriched 2D Multi-Scale Model Based on a Cosserat Continuum for the Analysis of Regular Masonry
Authors: De Bellis Maria Laura , Addessi Daniela , Ciampi Vincenzo , Paolone Achille
Published: January 2010

A multi-scale nonlinear homogenization procedure is presented for the analysis of the in-plane structural response of masonry panels characterized by a regular texture. A Cosserat continuum model is adopted at the macroscopic level, while a classical Cauchy model is employed at the microscopic scale; proper bridging conditions are stated to connect the two scales. The constitutive behaviour of bricks and mortar at the microscopic level is based on a scalar damage model, non symmetric in tension and compression. As for the regularization of the strain softening response, the standard fracture energy method is used at micro-level, while at the macro-level the inner capabilities of Cosserat continuum are exploited. A numerical example is presented and a comparison with an experimental test is performed.
Nucleation with Collapse of Acoustic Cavitation in Molten Al-Si Alloys
Authors: Fukui Yuta , Tsunekawa Yoshiki , Okumiya Masahiro
Published: January 2010

Ultrasonic irradiation during the solidification of molten metals has an effect on grain refinement. However, the mechanism of grain refinement by ultrasonic vibration has not been fully understood yet, so that there exist difficulties to apply the ultrasonic grain refinement to industrial casting processes. In the present study, we propose the mechanism of ultrasonic grain refinement: the nucleation is based on the extremely high pressure generated by the collapse of acoustic cavitation in molten Al-Si alloys. The effect of ultrasonic irradiation into molten Al-Si alloy on the microstructure was firstly studied, that is, molten Al-12.6wt%Si alloy was rapidly cooled down from just above the eutectic temperature after the ultrasonic irradiation. The detailed microstructure observation exhibits that ultrasonic irradiation above the eutectic temperature causes crystalline -Al and silicon to nucleate. Through the measurement of silicon content in -Al nodules solidified with ultrasonic irradiation, the silicon content is higher than that in non-irradiated -Al nodules. It is known that the collapse of acoustic cavitation generates extremely high pressure. At the highly pressurized sites, the eutectic temperature rises and the crystallized -Al nodules contain higher amount of silicon compared with those solidified at ambient pressure. According to the fact that the -Al nodules crystallized above the eutectic temperature contain higher amount of silicon, the irradiated microstructure of -Al nodules is developed at the highly pressurized sites, that is, the collapse of acoustic cavitation induces nucleation and causes grain refinement.
Effect of Rolling Speed on Deformability and Microstructure in Rolling of AZ31B Magnesium Alloy
Authors: Hamada Go , Sakai Tetsuo , Utsunomiya Hiroshi
Published: January 2010

Magnesium alloys are expected to be used widely as structural materials because of their lowest density (1.8g/cm3) among all practical alloys and superior specific strength. However, magnesium alloys exhibit poor ductility due to its hcp structure and inactiveness of non-basal slip systems below 523K. Accordingly, magnesium alloy sheets had to be rolled at elevated temperature to avoid edge cracking and fracture during rolling. The present authors succeeded in single pass large draught rolling of AZ31 magnesium alloy sheets below 473K without heating rolls by rolling at the speed higher than 1000m/min. The rolled and quenched sheets had fine recrystallized microstructure and exhibited excellent mechanical properties. It was found that the high speed rolling is a promising method not only for increasing productivity but also for controlling microstructures and improving mechanical properties. If the above mentioned advantages of high speed rolling can be drawn from the rolling at the speed lower than 1000m/min, it is possible to mass-produce magnesium alloy sheets having superior mechanical properties at lower cost. In this study, we tried to determine the lower limiting rolling speed at which we can obtain advantages of high speed rolling. We revealed that the thickness could be reduced about 60% by single pass operation even at 250m/min without heating rolls. The rolled and quenched sheets had equiaxed fine recrystallized microstructure. For example, the mean grain size of 2.1m was obtained in the AZ31B sheet rolled at 250m/min at room temperature to the reduction of 60%.
Fem Calculations and Experimental Determination of Residual Stresses in Alumina/Nickel Alloy Joints. Optimization of Fabrication Parameters
Authors: Hattali M.L. , Valette Stéphane , Ropital François , Mesrati N. , Treheux Daniel
Published: January 2010

The study relates to joints fabricated by solid state bonding between alumina and nickel alloy HAYNESTM214®, using an intermediate nickel metallic foil. Experimentally, damages and cracks often are observed close to the metal/ceramics interface. Consequently, the residual stresses distributions in the specimen were characterized experimentally using X-ray diffraction (XRD) and indentation techniques and predicted by Finite Element Analysis (FEA) calculations using an elastic-plastic-creep model. We demonstrate that a good correlation between FEA calculations and experimental results is obtained. Then, the effect of elaboration and geometrical parameters has been studied in order to minimize the residual stresses in alumina close to the metal-ceramics interface. However, the Al2O3/Ni/HAYNESTM214® system always leads to high residual stresses. To solve this problem, we show that the use of a multi-layer Cu/Ni/Cu joint, associated with the Direct Copper Bonding method (DCB), by pre-oxidation of copper, allows reducing significantly the tensile residual stresses in ceramics.
Microstructure Refinement of As-Cast Single Crystal Superalloys by Re-Solidification
Authors: Hegde S.R. , Kearsey Rick M. , Saari H. , Beddoes J.
Published: January 2010

Recently identified re-solidification behaviour of heavily alloyed single crystal super¬alloys has been incorporated into the Bridgman method. The process variables of resolidifcation temperature and mould withdrawal rate have been optimized. The microstructure, microporosity and eutectic phase fraction of re-solidified specimens were analyzed and compared with conventionally cast single crystal specimens. The potential advantage of this modified method has been illustrated by performing solution heat treatments on both re-solidified and normally cast specimens followed by eutectic phase fraction analysis.
A Markov Chain Fracture Model for Intergranular Crack Propagation in Polycrystalline Materials
Authors: Arafin Muhammad A. , Szpunar Jerzy A.
Published: January 2010

A model for intergranular damage propagation in polycrystalline materials is proposed, based on Markov Chain theory, Monte Carlo simulation and percolation concept. The model takes into account crack branching and coalescence, multiple crack nucleation sites, crack-turning etc., as well as the effect of grain boundary plane orientations with respect to the external stress direction. Both honeycomb and voronoi microstructures were utilized as the input microstructures. The effect of multiple crack nucleation sites has been found to have great influence on the crack propagation length. It has been observed that percolation threshold reported in the literature based on hexagonal microstructure is not applicable when the effect of external stress direction on the susceptibilities of grain boundaries is considered. The successful integration of voronoi algorithm with the Markov Chain and Monte Carlo simulations has opened up the possibilities of evaluating the intergranular crack propagation behaviour in a realistic manner.
Microstructure Evolution in a 3%Co Modified P911 Heat Resistant Steel under Creep Conditions
Authors: Kipelova Alla , Kaibyshev Rustam , Belyakov Andrey , Schenkova Izabella , Skorobogatykh Vladimir
Published: January 2010

The microstructural changes in a 3%Co modified P911 heat resistant steel were examined under static annealing and creep at elevated temperatures. The quenched steel was tempered at temperatures ranging from 673 to 1073 K for 3 hours. The temperature dependence of hardness for the tempered samples exhibits the maximum at 723 – 823 K which is associated with the precipitations of fine carbides with an average size of about 20 nm. The transverse lath size of martensitic structure is  200 nm after air quenching and remains unchanged under tempering at temperatures below 800 K. An increase in tempering temperature to 1073 K resulted in hardness drop. Coagulation of carbides and growth of martensitic laths takes place at these temperatures. The creep tests were carried out at 873 and 923 K up to rupture, which occurred after about 4.5 × 103 hours. The structural changes in crept specimens were characterized by the development of coarse laths/subgrains. The mean transverse size of which was  0.67 and  1.3 m after the creep tests at 873 and 923 K, respectively. On the other hand, an average size of second phase particles of  165 nm was observed in the samples tested at both temperatures.
Phase Constitution and Mechanical Property of Ti-Cr and Ti-Cr-Sn Alloys Containing 3D Transition Metal Elements
Authors: Kusano Yasuhiro , Inamura Tomonari , Hosoda Hideki , Wakashima Kenji , Miyazaki Shuichi
Published: January 2010

Effects of 3d transition metal element additions on phase constitution at room temperature and mechanical properties of Ti-Cr and Ti-Cr-Sn alloys were investigated in this study. Ti-5Cr and Ti-5Cr-3Sn (in mol%) alloys with or without 3mol% of 3d-transition-metals of V, Mn, Fe, Co and Ni were investigated. X-ray diffraction analysis showed that Ti-5Cr binary and Ti-5Cr-3Sn ternary alloys consisted of α' (hcp) and β (bcc) two phases, and the others were β single phase. Then, the additions of the 3d transition metals stabilize  phase. The results were in good agreement with optical microscopy observation. Vickers hardness tests revealed hardening occurred by the additional elements, and the hardening must be mainly due to solid solution hardening. Besides, the hardness was lowered by 3mol%Sn addition. Tensile tests revealed that the additions of Fe, Co and Ni improve strength while V and Mn improve ductility.
Effect of Delta Phase on the Hot Deformation Behaviour and Microstructural Evolution of Inconel 718
Authors: Lalvani Himanshu M. , Rist Martin A. , Brooks Jeffery W.
Published: January 2010

In order to investigate the influence of -phase precipitation during high temperature forging of Inconel 718, hot axi-symmetric compression tests have been performed on specimens with two distinct initial microstructures: i) as-received material containing a dense population of  precipates at grain boundaries and along intragranular slip planes, and ii) material solution-treated to dissolve the  phase. Results indicate that the presence of  leads to a slight increase in peak stress and a proportionately greater post-peak reduction in flow stress, as compared to solution-treated material. For both types of microstructure flow softening is associated with grain refinement, but in different ways: in -free material conventional dynamic recrystallisation leads to the formation of new grains, whereas the presence of plate-like  appears to cause the mechanical break-up and segmentation of prior grains.
The Effects of Hot Isostatic Pressing Conditions on the Microstructure of Beta-Gamma Titanium Aluminide Powder Alloys
Authors: Laurin D. , Seo Dongyi , Saari H. , Kim Young Won
Published: January 2010

The effects of hot isostatic pressing temperature and cooling rate on the microstructure of two powder metallurgy beta-gamma titanium aluminide alloys with nominal compositions TiAl 4Nb 3Mn (G1) and TiAl-2Nb-2Mo (G2) are investigated. Particular attention is placed on the volume fraction of the beta phase, which is known to improve the hot workability. The alloys are consolidated by hot isostatic pressing at 1200 °C, 1250 °C, and 1300 °C, and cooled at rates between 3.0 °C/min and 17.5 °C/min. The volume fraction of beta phase in both alloys was unaffected by the change in cooling rates. The volume fraction of the beta phase in G2 decreased linearly from ~9.5 vol.% to ~3.5 vol.% with increasing HIP temperature from 1200 °C to 1300 °C.
Structure of CaO-SrO-TiO2-P2O5 Glasses and their Ion-Releasing Abilities in Tris Buffer Solution
Authors: Lee Sung Ho , Obata Akiko , Kasuga Toshihiro
Published: January 2010

SrO-containing calcium phosphate invert glasses, (60-x)CaO∙xSrO∙30P2O5∙7Na2O∙3TiO2 (mol%, x = 0 ~ 60), which are expected to inhibit bone resorption by osteoclast and enhance bone formation, were prepared and estimated in their ion release behavior in Tris buffer solution. The glasses gradually released ions and the dissolved amounts of ions were the smallest when the glass contained 20 mol% of SrO. Laser Raman spectra showed that the peaks of phosphate groups and TiOy polyhedral groups red-shifted with increasing the SrO content in the glasses. The red-shift is suggested to be due to decrease in bonding strength between cations and phosphate groups or TiOy polyhedral groups in the glasses. In the case of the glasses containing SrO over 20 mol%, no Raman peaks of TiOy polyhedral shifted. TiOy (y = 4 or 6) polyhedral in the glasses can coordinate with cation up to 18 mol% since they contain 3 mol% of TiO2. Sr2+ ions are supposed to preferentially coordinate with TiOy polyhedral, the formation of this structure would induce the decrease in the ion amounts released from the glasses containing 0 ~ 20 mol% of SrO.
Role of Dilatometer in Designing New Bainitic Steels
Authors: Soliman Mohamed , Asadi Mehdi , Palkowski Heinz
Published: January 2010

Dilatometric measurements were used to design the processing parameters of two types of bainitic steels. The first type is a hypoeutectoid ultra fine bainite steel, for which the dilatometer was used to locate the temperature at which cementite is completely dissolved during intercritical annealing (TC). The intercritical annealing temperatures are then selected will above TC. To obtain the martensite start temperatures (MS), the steel is quenched to the room temperature (RT) from these selected temperatures and then the bainite transformation temperatures were selected to be well above MS. The dilatometer was then used to monitor the bainite transformation kinetics from which the required time frames for cessation of the bainitic reactions were estimated.
In the second type, bimodal bainite had been produced in thermo-mechanically processed TRIP-steel. A deformation dilatometer is used to perform three deformation-steps before slow cooling to form approx. 30% polygonal ferrite. The material was then rapidly cooled to the first bainite formation temperature. During this step, the dilatometer was used to monitor the bainite reaction from which the required time for 50% decomposition of austenite is estimated. The martensite start of the undecomposed austenite was located by quenching to RT. The second bainite transformation step was then performed well above the new MSII to form a second generation of finer bainite.
Crack-Healing Effectiveness of Nano Ni + SiC Co-Dispersed Alumina Hybrid Materials
Authors: Maruoka Daisuke , Sato Yoku , Nanko Makoto
Published: January 2010

Crack-healing effectiveness of nano-Ni+SiC co-dispersed Al2O3 hybrid materials by heat treatment was studied as well as oxidation behavior. The starting powder mixture was prepared by drying slurry consisting of distilled water, Al2O3, SiC powder and nickel nitrate. After reduction, the powder mixture was densified by pulsed electric current sintering. Cracks were introduced by a Vickers indenter. Specimens were exposed into air at temperature ranging from 1000 and 1300°C for 1 and 48 h. Thickness of oxidized zone in SiC+nano-Ni/Al2O3 thinner than nano-Ni/Al2O3. Cracks of SiC+nano-Ni/Al2O3 disappeared completely, for example, by oxidation at 1200°C for 6 h, as same as nano-Ni/Al2O3. Bending strength of crack-disappeared SiC+nano-Ni/Al2O3 showed 519 MPa and was comparable with that of as-sintered one. SiC+nano-Ni/Al2O3 pocesses crack-healing effectiveness with improved high-temperature oxidation resistance.
Multiple Precipitation Behavior of Niobium Carbide and Copper in Martensitic Steel
Authors: Murakami Masahiro , Nakada Nobuo , Tsuchiyama Toshihiro , Takaki Setsuo , Adachi Yoshitaka
Published: January 2010

The multiple precipitation behavior of NbC and Cu particles in martensitic structure was investigated by using 0.05C-0.46Nb-2Cu-1.5Mn steel (NbC-Cu steel). Additionally, 0.05C-0.45Nb-2Mn steel (NbC steel) and 2Cu-5Mn steel (Cu steel) were also prepared to examine the respective precipitation behaviors of NbC and Cu. Aging treatment at 873K after quenching revealed that these steels exhibit typical age hardening. Comparing the NbC steel and Cu steel in the precipitation rate, the Cu precipitated much faster than the NbC. On the other hand, the peak hardness in NbC-Cu steel is higher than that by the respective precipitations in NbC steel and Cu steel. Besides, the aging time for the peak hardness in NbC-Cu steel was between those in NbC steel and Cu steel. This suggests that the NbC and Cu particles were separately precipitated within martensite matrix and each of them contributed to the hardening in NbC-Cu steel. As a result of TEM investigation for crystallographic characteristics of the precipitates, the NbC and Cu particles had different crystallographic orientation relationship with tempered martensite matrix: Baker-Nutting relationship for NbC particle and Kurdjumov-Sachs relationship for Cu particle.
Bending Fatigue and Spring Back Properties of Implant Rods Made of β-Type Titanium Alloy for Spinal Fixture
Authors: Narita Kengo , Niinomi Mitsuo , Nakai Masaaki , Akahori Toshikazu , Tsutsumi Harumi , Oribe Kazuya
Published: January 2010

Implanting a spinal fixture using metallic rods is one of the effective treatments for spinal diseases. Because cyclic bending stress is loaded on the implant rods when patients move their upper bodies in daily life, bending fatigue properties are important for the implant rod. Further, the implant rods are bended plastically into a curved shape of spine by hand in a surgical operation. In that case, keeping shape is important, namely bending spring back properties are important factors. On the other hand, a biomedical β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (mass %) alloy (TNTZ), has been developed by the authors. Currently, this alloy are investigated to be applied to the above mentioned implant rod practically. Therefore, four-point bending fatigue and three point-bending spring back properties of TNTZ subjected various heat treatments were examined in this study.
TNTZ rods were subjected to solution treatment, and then some of them were subjected to aging treatment at 673 K or 723 K for 259.2 ks, followed by water quenching. Then, four-point bending fatigue and three-point bending spring back tests were carried out on TNTZ rods subjected to the various heat treatments mentioned above.
The bending fatigue strength at 2.5 million cycles in the high cycle fatigue region are not much different among any TNTZ rod. However, the bending fatigue strength of the Ti-6Al-4V ELI (Ti64) rod exceeds the fatigue strengths of every TNTZ rods in both low and high cycle fatigue regions. On the other hand, the lower spring back, which is a favorable property, was obtained for some TNTZ rod than Ti64 rod.
Design of Titanium Alloys Showing Plasticity Induced Transformation
Authors: Neelakantan Suresh , Rivera-Díaz-del-Castillo Pedro E.J. , van der Zwaag Sybrand
Published: January 2010

Due to Plasticity induced Transformation in metastable β-Ti-10V-2Fe-3Al (wt.%) alloy (PiTTi) upon deformation, a noticeable improvement in mechanical properties is observed. Among the main factors controlling such effect are the β grain size and its composition. Such phase transforms into martensite upon quenching. Its martensite start temperature (Ms) varies in accordance with its composition. Following Ghosh and Olson’s theory, a thermodynamics based model to predict the compositional dependence of the Ms temperature is developed, and successfully validated for Ti-X (X = Fe, Cr, Mo, V, Nb, Zr and Al) binary alloys. The model has been used to design new alloys displaying a tailored PiTTi effect.
Analysis of Residual Stress-Texture Relationships in Thin Films
Authors: Ortolani Matteo , Azanza Ricardo Cristy Leonor , Scardi Paolo
Published: January 2010

A new software was developed for the X-ray stress analysis of textured materials, especially useful in the case of thin films and coating. Literature data for a sputtered Cu thin film were used as a test case. Good agreement with the published results was found considering a grain interaction mechanism based on the combination of four models (Ruess/Voigt/Vook-Witt/inverse Vook-Witt). A similar value for the in-plane residual stress was obtained by the Eshelby-Kröner model, by optimizing the grain aspect-ratio. Main features and numerical/graphic output are briefly discussed.
Indirect Template Method of Magnetic Field Assisted Assembly
Authors: Rivero Rene D. , Padron Ivan , Booty Michael R. , Fiory Anthony T. , Ravindra Nuggehalli M.
Published: January 2010

Indirect Template Magnetic Field Assisted Assembly (IT-MFAA), a parallel processing technique, is presented. IT-MFAA is designed to assemble devices onto substrates through a versatile and scalable methodology, which is capable of adjusting to manufacturing situations and producing 100% yields with error correction. This paper discusses existing serial and parallel techniques and compares them to IT-MFAA. It demonstrates that IT-MFAA circumvents drawbacks present in other techniques, and outlines a model of IT-MFAA.
An Investigation into Cracking in Nickel-Base Superalloy Repair Welds
Authors: Rush Mathew T. , Colegrove Paul A. , Zhang Z. , Courtot B.
Published: January 2010

The nickel-base superalloy Rene 80 is considered very susceptible to liquation and strain-age cracking. Material in the solutionised condition is welded using the Cold Metal Transfer, or CMT process (with ductile filler alloy) and autogenously using a laser. Grain size is shown to have a significant effect on cracking. Using the CMT, welding power is shown to have high significance on the level of cracking, whereas welding speed has little effect. When welding using the laser, it is shown that the power and spot size are more crucial to the material cracking than the travel speed. It is indicated that the weld bead geometry has high significance over the occurrence of cracking, with a relationship between welding power, weld bead geometry, and stresses controlling the occurrence and magnitude of cracking. Further, some laser welds are analysed after post-weld heat treatment, and there is a significant increase in cracking after this. However, 34% of samples contained no cracking in both the as-welded and post-weld heat treated state.
Transformed Cuttlefish Bone Scaffolds for Bone Tissue Engineering
Authors: Battistella Elisa , Mele Silvia , Pietronave S. , Foltran Ismaela , Lesci G.I. , Foresti Elisabetta , Roveri Norberto , Rimondini Lia
Published: January 2010

Nature is full of many interesting things to work with, but many natural resources are also protected. In this view the recycling of aquaculture and fishery residues may lead to the manufacture of new devices and the isolation of new molecules with potential application in medicine. The aim of the present study was to explore the possibility to transform the cuttlefish bone into an hydroxyapatite scaffold suitable for bone tissue engineering application. The mixture of different lamellar porous structure of cuttlefish bone from the species Sepia Officinalis was selected and characterized, according to morphology (including porosity, surface development, surface characteristics) and mechanical properties. The material was transformed into suitable scaffold for bone tissue regeneration, trying to totally or partially convert calcium carbonate (aragonite) into calcium phosphate (hydroxyapatite HA) using hydrothermal transformation.
The studies on cell attachment and proliferation (by MTT assay at different experimental times), cell morphology with Scanning Electron Microscopy (SEM), alkaline phosphatase (ALP) and osteocalcin (OC) activities and expressions by mouse osteoblast-like MC3T3-E1 cells on HA were investigated at different experimental times in cultures, in comparison with those observed on titanium specimens used as a control (ET and ST). Cell proliferation was less in HA transformed cuttlefish bone scaffolds than in ET and ST specimens. In contrast, good performance for osteoblasts differentiation was observed on HA transformed cuttlefish bone scaffolds, similar to those observed onto titanium scaffolds.
Crack Tip Dislocations Observed by Combining Scanning Transmission Electron Microscopy and Computed Tomography
Authors: Sadamatsu Sunao , Tanaka Masaki , Higashida Kenji , Kaneko Kenji , Mitsuhara Masatoshi , Hata S. , Honda M.
Published: January 2010

Crack tip dislocations and dislocations introduced by three point-bending tests at high temperature are observed by combinating scanning transmission electron microscopy and computed tomography (STEM-CT). Commercially available P type (001) single crystal silicon wafers were employed. A series of STEM image was acquired from -60º to +60º in tilt range with 2º in tilt step. The diffraction vector was maintained close to g(hkl) = 220 during the acquisition by adjusting the [110] direction of the sample parallel to the tilt axis of the holder. Reconstructed images of dislocations revealed dislocation structures in three-dimension.
Anelastic Phenomena and Cr2N Precipitation in a High Nitrogen Austenitic Steel
Authors: Deodati Paolo , Montanari Roberto , Rovatti Ludovica , Ucciardello Nadia , Carosi Andrea
Published: January 2010

Internal friction (IF) and dynamic modulus measurements on a high nitrogen (0.8 wt%) austenitic steel in the temperature range from room temperature to 800 °C have been carried out by using a vibrating reed technique with electrostatic excitation and frequency modulation detection of flexural vibrations in the frequency range of kHz.
The IF spectrum of the as-prepared material shows a broad peak superimposed to an exponentially increasing background. The discontinuous precipitation of Cr2N phase changes the characteristics of the peak. The results have been discussed by considering interstitial-substitutional (i-s) interactions.
Drug Loaded, Biodegradable Nerve Conduits for the Simultaneous Chemical and Electrical Stimulation of Neural Cells as a Therapeutic Approach for Peripheral Nerve Regeneration
Authors: Schmidt Franziska , Ghalanbor Zahra , Thormann Frank , Kühbacher Markus , Bodmeier Roland , Gross Ulrich , Schubert Helmut , Zehbe Rolf
Published: January 2010

Restoring peripheral nerve trauma is an important research field in regenerative medicine. One therapeutical approach is to use tissue engineered nerve conduits consisting of biodegradable polymers. These materials can be designed to include active agents to further stimulate or influence proliferation, maturation, differentiation or migration of specific neuronal cell in these nerve guides. We have developed a method to electrically deposit and immobilize neuronal cells and extracellular matrix proteins on self structured micro electrodes. These electrodes also present a feasible methodology to investigate electrical stimulation of nerve cells. In our approach, poly-D,L-lactide-co-glycolides (PLGA) were investigated as possible substrate for these electrodes, while further allowing for the integration of model substances in a drug release concept. In a first approach, caffeine was used due to its well known effect of both stimulating and inhibiting effects on certain neuronal cells, while also allowing easy incorporation into PLGA via chemical means. A Plackett-Burman experimental design was used to find the optimum composition among different parameters such as drug concentration, polymer concentration, type of solvent and film-drying condition. The optimized drug loaded polymer films were tested for their release and degradation profile, and their behavior in cell culture. Finally, we are currently establishing an integrated experimental setup, combining caffeine modified PLGA film substrates with the manufacturing of the electrode structures to investigate cell deposition via electrical means and stimulation/ inhibition via chemical release.
Residual Stress Evaluation of Railway Wheels by X-Ray Diffraction and Finite Element Method
Authors: Takahashi Shunichi , Kato Takanori , Suzuki Hiroshi , Sasaki Toshihiko
Published: January 2010

X-ray stress measurement is useful for determining, in a non-destructive manner, the surface stresses of engineered parts.　However, the railway wheels cannot measure because this it is very large. So it should be measured using a scaled-down model. The problem is, however, how the stress release should be considered. In this analysis, the finite element method (FEM) was applied to estimate the initial stress state using stresses released after cutting a sample obtained by the X-ray method. Railway wheels were studied in this experiment. In the early 1990s, several railroads in the northeast of the U.S.A. experienced extensive cracking in the wheels of the commuter trains. Residual stresses in the hoop direction play an important role in mechanism fatigue damage. This paper will discuss about residual stress in the hoop direction in manufactured wheels. The results of FEM analysis and the X-ray diffraction method confirms that these methods can be used to evaluate the residual stress of the hoop direction. There is very good quantitative agreement between the simulated and measured stress distributions. It can be suggested that guessing guess stress release and the redistribution by the FEM analysis is possible. The residual hoop stress of the unused wheel presumed by this research has the residual stress of high compression in the wheel at the center of the rim up to 40mm depth.　It is very safe because the residual stress state is compressive even when a crack occurs, and obstructs the crack’s progress. If a crack occurs by any chance, the stress state can obstruct the crack’s progress.
Effects of Combined Zr and Mn Additions on Dispersoid Formation and Recrystallisation Behaviour of AA2198 Sheet
Authors: Tsivoulas Dimitrios , Prangnell Phil B. , Sigli Christophe , Bès Bernard
Published: January 2010

The present paper focuses on the influence of combined additions of Zr and Mn on the recrystallisation resistance of aluminium alloy 2198 sheet. Dual additions of these dispersoid forming elements have previously been reported to be beneficial for reducing recrystallisation during solution treatment, as they exhibit opposing microsegregation partitioning on solidification. Contrary to expectation, it was found that the addition of Mn, to a standard Zr-containing 2198 sheet material, reduced recrystallisation resistance. The reasons for this behaviour are explored by analysis of the morphology, size, chemistry, and distribution of the dispersoid families formed, as a function of the Mn and Zr level, traced back to the homogenisation stage.
Phase Equilibrium of the AuMn-Cu2MnGa System
Authors: Tsutsumi S. , Hosoda Hideki , Inamura Tomonari , Wakashima Kenji
Published: January 2010

Phase equilibrium and phase constitution of the Au-Cu-Ga-Mn quaternary system at 873 K was studied along the AuMn-Cu2MnGa (=CuMn0.5Ga0.5) both of which are ferromagnetic shape memory alloys. Three alloys were investigated: AuMn, Cu2MnGa and Au0.5Cu0.5Mn0.75Ga0.25 (AuMn:CuMn0.5Ga0.5=1:1). It was found that 1 ordered bct phase with the axis ratio c/a=0.948 was formed in the AuMn alloy due to the Mn reduction by evaporation during melting. The CuMn0.5Mn0.5 alloy was composed of MgZn2-type Laves phase and Cu9Al4-type  phase. Besides, the following three phases existed in the Au0.5Cu0.5M0.75Ga0.25 alloy: Laves,  and 2 ordered bct with c/a=1.041. The c/a value of the ordered bct phase is decreased by Cu and/or Ga substitution in AuMn. The values of electron atom ratio (e/a) calculated based on chemical compositions for the  phases were 1.61 and 1.68, which were close to the ideal value of 1.62 (=21/13). Based on the results, ordered bcc  (transforming into bct at lower temperature), and Laves are judged to be equilibrium phases at 873 K along the AuMn-Cu2MnGa.
FEM Modelling of Recrystallization Behaviour for Near-Alpha Ti Alloy IMI834
Authors: Vo Phuong , Jahazi Mohammad , Yue Stephen
Published: January 2010

The recrystallization behaviour of near-alpha titanium alloy IMI834, which is primarily used for high temperature aerospace compressor disc applications, has been investigated at hot working temperatures. The latest results of a finite element model, developed using the commercial code DEFORM-3D with constitutive equations adapted from available literature, will be presented. Model development and validation involved the hot compression of specimens with an initial bimodal alpha+beta microstructure at temperatures of 1000°C-1100°C, strain rates of 0.01s 1-1s 1, and varied post-deformation annealing times. The characterization of microstructure through quantitative metallography revealed beta grain refinement achieved primarily through static/metadynamic recrystallization. The beta recrystallization kinetics were subsequently predicted through an Avrami-type relationship.
A Nonlinear Transformation Field Procedure for Periodic Masonry Based on an Equivalent Cosserat Medium
Authors: Sacco E. , Addessi Daniela , Paolone Achille
Published: January 2010

The paper deals with the problem of the determination of the in-plane behavior of periodic masonry material. The masonry is considered as a composite material obtained as a regular distribution of blocks connected by horizontal and vertical mortar joints. The macromechanical equivalent Cosserat medium is derived by a rational homogenization procedure based on the Transformation Field Analysis. The micromechanical analysis is developed considering a Cauchy model for the masonry components. In particular, linear elastic constitutive relationship is considered for the blocks, while nonlinear constitutive law is adopted for the mortar joints, accounting for the damage and friction phenomena occurring during the loading history. Numerical applications are performed in order to assess the performances of the proposed procedure in reproducing the mechanical behavior of the masonry material.
Evolution of Residual Stress in Cu-Line Patterns with Different Linewidth
Authors: Wang Jian Feng , Ma Da Yan , Xu Ke Wei , Liu Ming
Published: January 2010

The Cu-line patterns with different linewidth were deposited by radio-frequency sputtering and defined by photolithography lift-off process. The residual stress was evaluated with X-ray diffraction technique and the results show that the Cu-line patterns are in a biaxial stress state and the stress values have a great dependence on linewidth. Further analysis reveals that the intrinsic stress has a main effect on changes of residual stress; however, the thermal stress plays a key role on anisotropic contribution of residual stress in directions along and across the Cu line. The variation of intrinsic stress correlates well with crystal orientation of the Cu line, and the linewidth seems to be the most crucial parameter for evolution of both texture and stress.
Magnetostrictive Properties of Epoxy-Bonded Tb0,3Dy0,7Fe1,9 Composites
Authors: Dobrzański Leszek Adam , Wydrzyńska Anna , Iesenchuk Oleksii , Żuberek Ryszard
Published: January 2010

Tb0,3Dy0,7Fe1,9 composites attract much attention due to their large magnetostriction, and small eddy current losses. In this work intelligent polymer matrix composite materials consisting of Tb0,3Dy0,7Fe1,9 particles was obtained by mixing epoxy resin and Tb0,3Dy0,7Fe1,9 powder with grains from 38 to 106 μm. The relationships among the manufacturing technology of these materials, their microstructure, as well as their magnetostriction were evaluated. Resulting composites can extend the possibilities of application the magnetostrictive materials simultaneously reduce the cost of Tb0,3Dy0,7Fe1,9.
Cold Spray Characteristics of Commercially Pure Ti and Ti-6Al-4V
Authors: Wong Wilson , Rezaeian Ahmad , Irissou Eric , Legoux Jean Gabriel , Yue Stephen
Published: January 2010

Ti and Ti-6Al-4V coatings were deposited by cold gas dynamic spray process using nitrogen as propellant gas. For Ti, the inlet gas temperature and pressure were varied for two different powder morphologies in such a way that the average particle velocity ranged from ~600 to 850 m/s. In addition, the nozzle traverse speed was varied. For all conditions, the deposition efficiency, the porosity, and the microhardness were measured. It is shown that the porosity level decreased as the gas temperature and pressure increased, whereas the velocity, deposition efficiency, and microhardness increased. Furthermore, it is observed that a lower nozzle traverse speed engendered a softer coating. The coating adhesion on a grit 24 Al2O3 blasted mild steel surface was established to be greater than 78.8 MPa. In addition, a Ti-6Al-4V coating was produced and was determined to be slightly more porous compared to a CP Ti coating.
Crystallographic Texture of Induction-Welded and Heat-Treated Pipeline Steel
Authors: Yan P. , Güngör Özlem Esma , Thibaux Philippe , Bhadeshia Harshad K.D.H.
Published: January 2010

Large-diameter steel pipes are produced by induction seam-welding followed by induction-assisted heat treatment. The microstructure and distribution of crystal orientations have been studied and related to the mechanical properties of the welded regions. The welding and heat-treatment process leads to a microstructure, a simple observation of which can not explain the observed variations in toughness in the vicinity of the welding joint, because the crystallographic grain size, which represents the scale of similarly oriented adjacent grains, is much coarser than the ordinary grain size. Furthermore, heating the affected zone into the austenite phase field followed by cooling does not completely eliminate the coarse regions of similarly oriented grains. The consequences of this on mechanical properties are discussed.
A TEP Study on the Microstructural Development in AA2024 during Interrupted Ageing
Authors: Yin M. , Risanti D.D. , Chen Jiang Hua , van der Zwaag Sybrand
Published: January 2010

This work utilizes thermoelectric power (TEP) measurement to track secondary precipitation during the interrupted ageing cycle for AA2024 alloys as well as the subsequent re-ageing cycle. Clear evidences of secondary precipitation were observed which affect the further precipitation sequence during re-ageing. The TEM results confirm that S and S” phases co-exist upon re-ageing.
Microstructural Characterization of Ti6Al4V-SiCf Composite Produced by New Roll-Bonding Process
Authors: Deodati Paolo , Donnini Riccardo , Kaciulis Saulius , Mezzi Alessio , Montanari Roberto , Testani Claudio , Ucciardello Nadia
Published: January 2010

Roll Diffusion Bonding (RDB) is a new process, developed at C.S.M., for producing Ti composites reinforced by long fibres. The prototypal “diffusion bonding” plant permits to co-roll at high temperature in superplastic rolling field (under temperature and strain rate control) foils of titanium alloy and fabrics made of SiC monofilaments.
This study evidenced that the Ti6Al4V-SiCf composite produced by roll-bonding exhibits superior mechanical properties with respect the same material prepared by Hot Isostatic Pressing (HIP) owing to the smaller grain size and the higher dislocation density.