bluuebunny/crossref_metadata_2025 huggingface dataset:
Orientation Spread in Deformed Grains and Its Relevance to Recrystallization Texture Development in IF Steels
Authors: Kang Jun Yun , Kim Dong Ik , Oh Kyu Hwan , Lee Hu Chul
Published: March 2009

Deformation characteristics of cold rolled grains and their contribution to the development of recrystallization texture in IF steel were investigated using EBSD. Quantitative evaluation of the intra-granular orientation spread in the deformed grains was attempted. Both of the GAM and SGS could represent the orientation spread but in different manner. The GAM value was higher in {111}//ND orientations than in other orientation groups implying steep orientation gradient within short ranges in {111}//ND oriented grains. This steep orientation gradient was generally originated from the existence of deformation heterogeneities. Particularly, {111}<112> orientation which was the dominant component in the recrystallization texture showed the maximum values of both GAM and SGS, which was caused by the frequent development of shear bands. SGS values of {001}//ND oriented soft grains were unexpectedly large in spite of their small GAM values. It could be confirmed that their uniform deformation behavior led to the gentle but monotonous orientation gradient in long ranges. The lowest values of both GAM and SGS were obtained in the {112}<110> orientation, probably, because of the highest orientation stability in that orientation during plain strain deformation condition. GAM was more closely related to the development of recrystallization texture and the significance of the steep orientation gradient in the recrystallization behavior should be re-addressed.
Crystallographic Distribution of Internal Interfaces in Spinel Polycrystals
Authors: Miller Herbert M. , Saylor David , El Dasher Bassem S. , Rollett Anthony D. , Rohrer Gregory S.
Published: March 2009

Measurements of the grain boundary character distribution in MgAl2O4 (spinel) as a function of lattice misorientation and boundary plane orientation show that at all misorientations, grain boundaries are most frequently terminated on {111} planes. Boundaries with {111} orientations are observed 2.5 times more frequently than boundaries with {100} orientations. Furthermore, the most common boundary type is the twist boundary formed by a 60° rotation about the [111] axis. {111} planes also dominate the external form of spinel crystals found in natural settings, and this suggests that they are low energy and/or slow growing planes. The mechanisms that might lead to a high population of these planes during solid state crystal growth are discussed.
Influence of Particle Mechanisms on Kinetics of Grain Growth in a P/M Superalloy
Authors: Huda Zainul
Published: March 2009

The current literature reports the quantitative analysis of the kinetics of grain growth influenced by second-phase particle mechanisms for a powder metallurgy nickel-base superalloy: APK-6. Annealing treatments in the superalloy are shown to involve coarsening/dissolution of γ’ particles, and these particles mechanisms are shown to influence the kinetics of grain growth. The grain-growth exponent, n, is computed, and the γ’-solvus temperature of the superalloy is determined to lie between 220 and 270 oC. The kinetic data is interpreted to establish dependence of γ’ particles coarsening/dissolution mechanisms, grain size, γ’-solvus temperature, and annealing time and temperature on the rates of grain growth in the superalloy.
In-Situ Quantification of Solute Effects on Grain Boundary Mobility and Character in Aluminum Alloys during Recrystallization
Authors: Taheri Mitra L. , Rollett Anthony D. , Weiland Hasso
Published: March 2009

Aluminum alloys exhibit recrystallization kinetics that vary strongly with composition. The conventional understanding is that certain alloying elements, e.g. chromium, retard grain boundary motion due to the formation of fine dispersions of second phase particles, giving rise to particle drag of boundaries. There is countervailing evidence, however, that suggests that solute drag provides a stronger influence on grain boundary mobility. This paper presents new evidence for a pronounced effect of solute based on experiments in which individual boundaries migrate under the driving pressure of stored energy from prior plastic strain. As supported by the literature, boundaries exhibit a maximum mobility for a 38-39 degree <111> misorientation in initial annealing experiments. Specifically, this mobility maximum is asymmetric with a sharp cutoff below 38-39 degrees but a more gradual decrease at misorientations beyond 40 degrees. The occurrence of other, smaller mobility peaks is discussed within the context of the sharpening of evolving maxima with discussed within the context of the sharpening of evolving maxima with increased recrystallization. The presence of a minimum at 38-39 degrees is found at both higher temperatures and higher solute concentrations. This transition from a local mobility maximum to a minimum is discussed within the context of recent theories solute drag activity.
Removal Mechanism in Wire-Sawing of Hard-Brittle Material
Authors: Meng J.F. , Li Jian Feng , Ge Pei Qi , Gao W.
Published: March 2009

A better understanding of the hard-brittle material removal mechanism in wire-sawing provides a basis for optimizing the wire-saw and processing parameters. The maximum cutting depth of each diamond grain in wire-sawing is given. It is proved theoretically that the deformation mode on the machined hard-brittle material surface gradually shifts from brittle fracture to ductile deformation with the increasing of wire-saw velocity, the decreasing of infeed velocity and the decreasing of average grain size. The experimental investigation on the wire-sawing of granite is carried out. It is shown that in the case of wire-saw velocity of 20m/s, infeed velocity of 0.15mm/s and diamond grain size of 200~230#, the removal mechanism in wire-sawing is ductile mode.
Preparation of Agglomerate-Free Starting Powders for TiCp-Reinforced β-Sialon Nanocomposites
Authors: Lü Z.J. , Ai Xing , Zhao Jun
Published: March 2009

By changing the molecular weight and concentration of dispersant, PH value of dispersion solution and treat process, this paper focuses on the optimization parameters of the TiCp-reinforced ß-sialon nanocomposites suspensions. Zeta potentials, sedimentation tests have been carried out to prepare a well reagglomerated and uniform suspensions. The optimum molecular weight of PEG is
1540 for Al2O3 powder and 4000 for others, while the concentration is 0.5wt% to 0.8wt% with the pH values range from 9.5 to 10. After addition of dispersant, PEG (polyethylene glycol), the surfaces of the TiC particles and Sialon contents were selectively covered with long organic molecular chains by soaking within solution. The resulting powders not only resisted reagglomeration, but were also readily dispersible within the mixed solution. Optimum dispersion conditions, i.e. the surfactant molecular weight and the concentration, the PH value of the suspens ions and the soaking time were determined.
Study on Machining of Hard-Brittle Materials with Thin-Walled Monolayer Brazed Diamond Core Drill
Authors: Su Hong Hua , Xu Hong Jun , Xiao Bing , Fu Yu Can , Xu Jiu Hua
Published: March 2009

A new method for fabricating the thin-walled diamond core drill by brazing technology
and the optimum grain distribution was proposed in this paper. Machining performance experiments have been carried out, including contrast tests about drill life and machining efficiency for the thin- walled monolayer brazed diamond core drill and electroplated one. The testing results show that thin-walled monolayer brazed diamond core drill has certainly super-excellent machining performance. Wear mechanism of diamond grits was studied in tho se drilling processes. No pulling out for the thin-walled monolayer brazed diamond core drill grits is the key factor of its longer life, and the optimum grain distribution and less wear flat of grits during drilling decrease the drilling spindle direction force, and improve the machining efficiency. It can be concluded that the new technology can radically improve the bonding strength at the grains interface, and make every grain effective during drilling.
A Method to Forecast the Cohesive Zone of Blast Furnace
Authors: Li S.Z. , Cheng Jian , Ma W.Q.
Published: March 2009

The paper describes a method to forecast the cohesive zone of blast furnace whose shape is very important for the quality of iron and the efficiency of iron-making industry. This method builds a model that can be observed during the operation of iron making. The model considers that during the chemical reaction the ore, the coke and the gas abide by two equations: the equation of conservation of
mass and the equation of heat conservation. Based on this presumption, by dividing the blast furnace into a series of homocentric circles in the height direction and resolving the equations in every homocentric circle with its own parameters, we can get the relationship between temperature and height of the inner blast furnace. And then, according to the fusibility character of the ore, we can forecast the shape and position of the cohesive zone. Finally, the paper visualizes the cohesive zone of
blast furnace and discusses some results achieved through the application of such method to a real blast furnace.
Wear of High Speed Steel Bi-Metal Bandsaw Blade when Cutting AvestaPolarit 17-7 Stainless Steel in the As-Cast State
Authors: Sarwar Mohammed , Persson M. , Hellbergh H.
Published: March 2009

This paper reports experimental data on the wear of high-speed steel bimetal bandsaw blades cutting austenitic 17-7 stainless steel bars. Several different methods of assessing the wear modes and mechanisms are evaluated; Cutting and thrust force components, Set width, Kerf width, “Out-of-square” cutting, Wear modes and mechanisms and Chip characteristics. The wear mode established in the current work when bandsawing austenitic stainless steel with a bimetal blade is flank and corner wear together with formation of a cutting edge radius. The cutting edge radius increases as the wear progresses, reaching 25-50 mm after 300 cut sections. The established wear mechanism for the initial stages of wear is mild adhesive wear of the flank surface together with built-up edge formation and break-down. As the wear reaches steady-state the mechanism is adhesive wear of the flank surface with tempering/softening of high-speed steel layers. When the wear reached the steady-state region the level of thrust and cutting force were equal and relatively high. The kerf width appears to be less than the total set width of the blade, meaning that there is compression of the set teeth as they pass through the kerf. There is segmented chip formation with an increasing amount of vibration as the teeth wear, probably due to the increasing size of cutting edge radius. This work should be of great interest to the tool designer and user associated with bandsaws.
Recent Developments in Tool Materials for High Speed Machining
Authors: Liu Zhan Qiang , Wan Yi , Ai Xing
Published: March 2009

High-Speed Machining (HSM) is one of the emerging cutting processes, which is machining at a speed significantly higher than the speed commonly in use on the shop floor. In the last twenty years, high speed machining has received an important attention as a technological solution for high productivity to increase economic efficiency in manufacturing. The recent developments in cutting tool materials for high speed machining are reviewed in this paper. The appropriate applications of the high speed machining technology are presented. The research is great beneficial to the design and the optimal selection of tool materials for high speed machining.
Forming Defects Analysis of Auto-Panel Stamped Part with Experimental Strain Approach
Authors: Xiang H.Y. , Zhong Yue Xian
Published: March 2009

This document explains and demonstrates an experimental method to determine principal plastic strains in industrially stamped sheet panels. The principal strains distribution after a given stamping process can be obtained using computer aided grid experimental method. In contrast with FLD (Forming Limit Diagram) obtained by the material testing, the measured results of strain distribution can be used to determine the sheet metal’s formability allowing to determine at which point the sheet metal cracks or uneven stretch occurs and other forming defects. The main principle and related theory of this approach are discussed. One automobile panel stamped part as a practical case was studied, the strain distribution of the part after a given stamping process was measured and calculated, a demonstration of how to deal with the results in comparison with FLD to determine and solve forming problems is analyzed.
Time Series Model Study on the NC Grinding Process of Isometric Polygonal Profile
Authors: Wang De Sheng , Zhou Ai Ping , Huang Pan Ling , Zhao X.Y.
Published: March 2009

This paper studies the NC grinding process for Isometric Polygonal Profiles (IPP) with self-made machine tools accessories, and establishes the time series model of the grinding process by means of measuring and analyzing the vibratory signal in the grinding process. The grinding experiment indicates that the surface formative motions of IPP can be achieved with the step-motor-driven accessories and it is reasonable to design the grinding machine for IPP according to the principle. This method solves the technical problems in IPP NC processing and can act as an important elicitation and illustration for NC processing other polygonal profiles.
Optimization of Technological Parameters in the Calescent Superplastic Bulge Forming of Ti-6Al-4V Alloys Sheet Based on Fuzzy Neural Network
Authors: Chen Ming He , Gao Lin , Zhu Z.S. , Zuo Dun Wen , Wang Min
Published: March 2009

The calescent superplastic bulge forming (CSPBF) of Ti-6Al-4V (TC4) alloy sheet was investigated using experimental method, and carried out the research that optimized its technological parameters using fuzzy neural network (FNN) . The experimental results show that the CSPBF may save processing time, can also improve materials’ formability as well as get ideal microstructure. The study indicated that the FNN adapt to solve complex nonlinear problem such as technological parameters of CSPBF of TC4 sheet. Utilizing optimized technological parameters successfully have formed the part of aerostat, the nonuniformity of wall thickness is less than 8% and part' forming time may be shorten 10minute.
Integrated Product Design Using Rapid Prototyping Technology and Rapid Tooling in Concurrent Engineering Approach
Authors: Das A.K.
Published: March 2009

Advancement and acceptance of Concurrent Engineering to speed up and improve
product development process requires a systematic approach to the integrated, simultaneous design of products and their related processes, including manufacture and support [1] and Rapid Prototyping [2] is the one versatile tool that meet this requirement. Rapid Prototyping involves virtual prototyping and provides physical models as an end product. Traditionally initial industrial design concepts are shown as renderings or drawings, that show the look and feel of the product. The construction of mock up is followed after selection of a particular concept and these looks exactly like final product in true form, colour, texture etc. but without working internal components. With the advancement of CAD, 2 types of prototyping are in use in product design for modeling and simulating products performances.
(a) Virtual prototyping using Analytical models
(b) Physical prototyping making physical models
These choices are influenced by variety of reasons. Physical prototypes are used for Communication purpose, Demonstration purpose, Scheduling /milestones, Feasibility study, Parametric modeling and Architectural interfacing. The above uses lead to a number of benefits such as insights into manufacturability and assemblability, accelerating of parallel activities and flexible product choices. In this paper, we are concerned from the point of view of an industrial designer for Integrated Product Development using concurrent engineering approach. Thus this paper highlights the benefits of Rapid Prototyping over conventional prototyping methods.
Study on Preprocessing Methods for Color 3D Point Cloud
Authors: Zhang X.D. , Sun Chang Ku , Wang C. , Ye S.H.
Published: March 2009

This paper provides a preprocessing flow for color three-dimension (3D) point cloud according to the characteristics of laser scanning data. The preprocessing methods and their functions are introduced in detail. Automatic system decision and manual polygon selection methods are applied to eliminate unwanted and noise data successfully, which possibly make improper color models reconstructed. A data reduction method is presented based on Grid reduction method considering color-boundary preservation. It can effectively avoid shape and color distortion in model reconstruction. Several experimental results are presented to indicate the feasibility and reliability of these methods, which can be broadly applied in various fields of products design, antiques and art wares digitization, etc.
Simulation for Guide Roll in 3D-FE Analysis of Cold Ring Rolling
Authors: Guo L.G. , Yang He , Zhan Mei , Li Heng , Li L.Y.
Published: March 2009

A simple and efficient method has been proposed in order to determine the dynamic speed boundary condition caused by the guide rolls for developing the 3D-FE model of cold ring rolling process rapidly. The concept of the motion track of guide rolls has been put forward firstly and an optimal motion track and track type are given by simulation. Meanwhile, an effect of the guide rolls on the ring tilting and ring circularity was simulated and analyzed. The result shows that the simulation results are in good agreement with experiment results from the literature.
Particle Swarm Optimization for Vehicle Routing Problem with Time Windows
Authors: Zhao Yan Wei , Wu B. , Wang W.L. , Ma Ying Li , Wang W.A. , Sun H.
Published: March 2009

The investigation of the performance of the Particle Swarm Optimization (PSO) method for Vehicle Routing Problem with Time Windows is the main theme of the paper. “Exchange minus operator” is constructed to compute particle’s velocity. We use Saving algorithm, Nearest Neighbor algorithm, and Solomon insertion heuristics for parameter initialization and apply the “Routing first and Cluster second” strategy for solution generation. By PSO, customers are sorted in an ordered sequence for vehicle assignment and Nearest Neighbor algorithm is used to optimize every vehicle route. In our experiments, two different PSO algorithms (global and local), and three construct algorithms are investigated for omparison. Computational results show that global PSO algorithm with Solomon insertion heuristics is more efficiency than the others.
Analysis of Step Interference Fit of the High Speed Motorized Spindle with Finite Element Method
Authors: Ma Ping , Liao Cheng Xiang , Duan M.L. , Li J.K. , Li D.N. , Zhang B.L.
Published: March 2009

Balance for high speed motorized spindle is most important, it will influence the dynamic behavior of the high speed machine tools. In this paper, the GD-IV high speed spindle is introduced. In order to improve its balance accuracy, the step interference fit is developed to connect the rotor and the shaft. The interference fitted assembly has been modeled theoretically, the analysis highlights that the tolerance of the interference fit consists of the static section and dynamic section, the static section is determined by the transmitting torque while the dynamic section is determined by the centrifugal force. The Calculation of interference fit for the GD-IV spindle shows that the dynamic section is about 4.5 times larger than the static. Furthermore, the three dimensional model of the step interference fit between the shaft and the rotor has also been built up with finite element method and the stress distribution on the mating surface has been calculated. The results show that the maximum stress occurring near the chamfer region of the internal surface of the rotor is up to 235 MPa lower than the permissible material stress 278 MPa, so that the design of the step interference fit is reliability and safety.
Formation and Characterization of Electric Contacts on CVD Diamond Films Prepared by Ion Implantation
Authors: Kovách Gergely , Csorbai Hajnalka , Dobos G. , Karacs Albert , Pető Gábor
Published: March 2009

Diamond layers have a potential application as the highest band-gap semiconductor for electronic devices. One of the major problems is to form electric contact on the diamond surface useful for an electronic device. This paper shows the properties of the contacts formed by the very promising ion implantation technique. The diamond layers were deposited with Microwave Assisted Chemical Vapor Deposition (MW-CVD) equipped with special extra features like High Voltage Bias and Heated
Substrate Holder [1]. Phosphoruos ion implantation and gold deposition were used for the contact formation. This technique resulted graphitization the top of the diamond film and intermixing of gold with the graphite or diamond surface. The properties of the contacts were tested with surface conduction characterization methods, and the properties of the contact to diamond interface was investigated with SIMS (Secondary Ion Mass Spectroscopy ) and XPS (X-ray Photoelectron
Spectroscopy).
Some Experiences of Tribological, Microstructural and Mechanical Investigation of Post Heat Treated SiAlON Ceramics
Authors: Berkes Maria Maros , Kiss Judit Babcsán , Kuzsella László , Arató Péter
Published: March 2009

Tribological performance of technical ceramics is influenced by various factors. Among the others the material properties, loading conditions, residual stresses as well as chemical reactions and interaction between contacting parts effect the damage process. The current paper focuses on the material features, investigating the possibility of modifying the wearing characteristics of a Si3N4 based technical ceramics by post-heat treatment. The microstructure, the mechanical properties and the wearing characteristics were studied on HIP-sintered SiAlON samples, post heattreated in oxidizing atmosphere at different temperatures. Wearing performance was characterized by pin-on disc tests. The wear rate varied with the temperature of heat treatment. From tribological point of view especially treatment at 1200°C proved to be advantageous Microstructural investigations by TEM and X-ray diffraction studies revealed some explanations of these changes. The above studies were completed by mechanical tests. Microhardness, E-modulus, four point
bending strength and indentation fracture toughness have been determined in order to study the correlation between the tribological and mechanical properties. Based on our results, the post heat treatment may be useful to improve the wearing performance of SiAlON ceramics.
Modelling of Filtration of Aluminium Melt Through Porous Pressed Filtering Sheets
Authors: Varga Béla
Published: March 2009

The paper analyses via hydraulic modelling the retaining mechanisms of solid non-metal inclusions in the filtration process of aluminium melts through pressed sheets. Experimental determinations via hydraulic modelling show that the variation of filter thickness influences significantly the retaining mechanism of solid non-metal inclusions and implicitly its productivity.
Assessment of Methods in Girth Welds of Steel Pipelines
Authors: Nagy Gyula , Lukács János , Török Imre
Published: March 2009

This paper presents two basic methods for the assessment of failed girth welds of steel hydrocarbon transporting pipelines. One of them is based on the principles of linear elastic fracture mechanics (LEFM) and stress intensity factor conception for planar material discontinuities, and the other can be used for the complex assessment of all kinds of occurring defects. The results of the presented methods are compared to the results of burst test of pipeline sections containing a failed girth weld and cut from a Hungarian gas pipeline.
Modeling the Infiltration of Liquid Metals Into Porous Ceramics
Authors: Bárczy Tamás , Kaptay György
Published: March 2009

A new “Closely Packed Equal Sphere” (CPES) infiltration model has been developed by us. It differs from the classical capillary infiltration model mainly in the value of the critical contact angle of spontaneous infiltration (50,7o, instead of 90o), and as a consequence, it also differs in the functional relationship between the threshold pressure and the contact angle. Our new equation becomes identical with the Carman equation for perfectly wettability. Our experimental results are
in good agreement with these theoretical results.
Evolution of the Microstructure of Al 6082 Alloy during Equal-Channel Angular Pressing
Authors: Gubicza Jenő , Krállics György , Schiller I. , Malgyn Dmitry
Published: March 2009

A commercial Al-Mg-Si alloy (Al 6082) was deformed by Equal-Channel Angular Pressing (ECAP) to produce bulk ultrafine-grained microstructure. The crystallite size distribution and the characteristic parameters of the dislocation structure were investigated by X-ray diffraction profile analysis. It was found that the crystallite size decreased and the dislocation density increased during ECAP deformation. The increase of the yield stress of the alloy was related to the increase of the dislocation density using the Taylor model.
Combination of CVD Diamond and DLC Film Growth with Pulsed Laser Deposition to Enhance the Corrosive Protection of Diamond Layers
Authors: Csorbai Hajnalka , Kovách Gergely , Pető Gábor , Csíkvári P. , Karacs Albert , Kálmán Erika
Published: March 2009

CVD diamond layers are often used as protective layers. One of the most important of these applications requires pinhole-free layers to protect against fluid materials, such as found in chemically aggressive environment. These pinholes are present even in very good quality CVD diamond films. In this work we combined the Pulsed Laser Deposition (PLD) technique with Microwave assisted Chemical Vapor Deposition (MW-CVD). We used CVD diamond films prepared under different conditions and layer thicknesses. Both of these proceses produced inperfect protective layers, but we proved that a PLD DLC film over the diamond layer does reduce the number of pinholes in the coating. We used special chemical alcaline etching to detect the remaining pinholes, and to test the corrosion protective properties of the layers. As a result we were able to prepare samples of 1 x 1cm2 with only 0.2 micron thickness without any pinholes, while in CVD diamond layers a thickness of 2,5 micron was needed for the same level of compactness.
Study on Densification Behavior and Microwave Attenuation Characteristics in AlN/SiC Composites
Authors: Li Xiao Yan , Qiu Tai , Wu Huazhong , Shen Chun Ying
Published: March 2009

AlN-SiC Composites were obtained by hot-pressing at 1900ı for 1h in a nitrogen
atmosphere. The influences of the amount of SiC on densification behavior and microwave attenuation characteristics were studied. The results showed that although the densification of composites decreased along with the increasing SiC content, it had no distinct influence on microwave attenuation characteristics. When the content of SiC increased, the attenuation of AlN-SiC composites increased within the range of 2 to 8 GHz. SiC is a kind of wide frequency attenuation agent.
An Analysis of Deformation and Fracture Behaviour of Zircaloy-4 Alloy Using Small Punch Test
Authors: Callaghan M.D. , Yeung Wing Yiu , Ripley Maurice I. , Carr David G.
Published: March 2009

The small punch (SP) test is a novel technique that uses a relatively small volume of material, to enable a measure of load versus deflection to determine the mechanical behaviour of the alloy. This study aims to investigate the mechanical properties of Zircaloy-4 (Zr-4) alloy which will be used for construction of many of the core components in ANSTO’s replacement research reactor at Lucas Heights in Australia. The Zr-4 alloy was hydrided under different conditions to simulate the radiation-induced reduction in fracture toughness over the service life of the reactor. The SP test was applied to determine the deformation and fracture behaviour of the hydrided materials. It was found that as the hydride formation increased, the equivalent fracture strain (eqf) of the alloy decreased to lower values.
Effect of Zr Addition on Phase Constitution and Heat Treatment Behavior of Ti-25mass%Nb Alloys
Authors: Ikeda Masahiko , Mori Masaaki , Hirasawa Takashi , Toyoshima Kazuya
Published: March 2009

In an attempt to optimize the shape recovery temperature, the effect of Zr addition on
phase constitution and heat treatment behavior is investigated by electrical resistivity and Vickers hardness (HV) measurements, X-ray diffractometry (XRD) and shape recovery tests. Ti-25mass%Nb-0, 2, 7 and 12mass%Zr alloys (abbreviated as 0Zr, 2Zr, 7Zr and 12Zr, respectively) were prepared using an arc-furnace. Specimens were solution-treated at 1273 K for 3.6 ks and then quenched by iced water (STQ). STQed specimens were isochronally heat-treated. In 0Zr and 2Zr, only the orthorhombic martensite phase a” was identified by XRD, while the two-phase alloys a” and b were identified in 7Zr and 12Zr. In 7Zr, resistivity at liquid nitrogen and room temperature (rLN and rRT, respectively) and resistivity ratio (rLN/rRT) drastically increased at 523 K
because of the reverse-transformation of a” into b phase. Thereafter, resistivity and resistivity ratio decreased with increasing heat treatment temperature due to isothermal w precipitation. Starting temperature of shape recovery is 623 K in 7Zr and 523 K in 12Zr. In 7Zr, shape recovery ratio is about 80% at 723 K, which is the maximum obtained in this study.
Development of Corrosion and Wear Resistant Coatings by an Improved HVOF Spraying Process
Authors: Ishikawa Yasunari , Kawakita Jin , Kuroda Seiji
Published: March 2009

We have developed an improved HVOF spray process called “Gas-shrouded HVOF” (GS-HVOF) over the past several years. By using an extension nozzle at the exit of a commercial HVOF spray gun, GS-HVOF is capable of controlling the oxidation of sprayed materials during flight as well as achieving higher velocity of sprayed particles. These features result in extremely dense and clean microstructure of the sprayed coatings. The process has been successfully applied
to corrosion resistant alloys such as SUS316L, Hastelloy C, and alloy 625 as well as cermets such as WC-Cr3C2-Ni. The spray process, coatings microstructure and property evaluation will be discussed with potential industrial applications in the near future.
A New Concept: Hydrogen Storage in Minerals
Authors: Mu Shi Chun , Pan M. , Yuan Run Zhang
Published: March 2009

Some minerals were considered to store hydrogen on the basis of their porous crystal structure. Besides of crystal graphite and zeolite, some natural clay minerals such as palygorskite-sepiolite minerals with nano-scale channels and polar surface can also store hydrogen. The hydrogen storage mechanism of porous minerals was discussed. The experimental results showed a potential application of palygorskite-sepiolite minerals as the media of hydrogen storage.
Synthesis and Properties of Nanostructured Mg2Ni-Based Compounds
Authors: Shao Huaiyu , Wang Yun Tao , Li Xing Guo
Published: March 2009

Mg, Ni and Cu nanoparticles were prepared by hydrogen plasma-metal reaction method. Nanostructured Mg2Ni and Mg2Ni0.75Cu0.25 compound were successfully obtained using the metal nanoparticles. The synthesis mechanism, the structure and lattice parameter difference, and the hydrogen absorption behaviors of the two compounds were discussed.
Alloy Design Based on Molecular Orbital Method
Authors: Morinaga Masahiko , Murata Yoshinori , Yukawa Hiroshi
Published: March 2009

A molecular orbital approach to alloy design has recently made great progress. Single crystal Ni-based superalloys and high Cr ferritic steels have been developed following this approach. Some perspectives will also be described on the design of heat resistant alloys.
A Unified Technology Combining Plastic Forming and Heat Treatment of Steels
Authors: Hsu T.Y.
Published: March 2009

In order to diminish the industrial pollution to maintain the sustainable development and to reduce the cost of the steel production, a unified technology combining plastic forming and heat treatment for some steel parts production is suggested. This article mainly concerns part theoretical foundation of such technology, i.e. the thermodynamic and kinetic models of the ferrite and pearlite transformations under external stress. Simulation of the ferrite fraction after continuous cooling under stress in a low-alloyed steel is presented. The effects of stresses on bainitic and martensitic transformations are also briefly introduced. The unified technology seems favorable to be realized in manufacturing practice.
Optimum Design of a Pilger Mill Process for Wire Forming Using CAD/CAE
Authors: Park Hoon Jae , Kim Seung Soo , Lee Sang Mok , Choi Tae Hoon , Lee Hee Woong , Lim Seong Joo , Kim E.Z. , Na Kyoung Hoan , Han C.S.
Published: March 2009

The optimum design of a die shape for Pilger mill process was carried out using FEM
analyses considering various processing factors. The important design parameters of the Pilger mill machine are feed rate and profile of the grooved die. Optimum design procedure was conducted in order to investigate effects on forming load and the deformed shape of a material depending on the die surface profiles. Profiles of the die surface for the optimum design were testified with linear, cosine and quadratic curves considering physical forming process. The results of the analyses provided that the model of the quadratic profile gave the lowest forming load and the proper deformed shape.
Stress Induced Anisotropic Diffusion during Plasma-Assisted Nitriding of a Ni-Based Alloy
Authors: He Huan , Zou Jian Xin , Dong Chuang , Czerwiec Thierry , Michel Henri
Published: March 2009

A special phenomenon, anisotropic diffusion is observed during plasma-assisted nitriding of a nickel-based alloy, Inconel 690. The diffusion rate is found to be higher in grains with an orientation close to <100> than in those grains with an orientation close to <111>. A model is established basing on the anisotropic strain and stress during nitriding so as to explain this phenomenon. It is shown that, the anisotropic stress in this f.c.c. alloy causes the different activation energy of N on various grain orientations, and finally result in the anisotropic diffusion rate of N in the alloy. Based on this model, a good agreement between calculated results and experimental results is obtained for temperatures below 400 °C.
The Influence of La on the Corrosion Resistance of Hot-Dip Aluminized Steel
Authors: Wen Jiu ba , Zhang Wei , Li Xiao Yuan , Li Quan An
Published: March 2009

The influence of the content of rare-earth La on the microstructure and
corrosion-resistance of hot-dipped aluminum was studied in this paper .The results show that ,under the same technology conditions, the thickness of hot-dipped aluminizing layer by adding the appropriate content of rare-earth La is about 2～3 times as much as that without rare-earth La, and the microstructure of hot-dipped aluminizing layer has also greatly changed ,and a great deal of phase Fe3Al was precipitated along the boundary of a phase. The corrosion resistance of the
hot-dipped layer with rare-earth La is greatly increased.
Surface Modification on Magnesium Alloys by Coating with Magnesium Fluorides
Authors: Ohse T. , Tsubakino Harushige , Yamamoto Atsushi
Published: March 2009

A new technique has been developed for improving corrosion resistance on magnesium alloys. Specimens of AZ31 magnesium alloy were dipped into molten salt of NaBF4 at 723 K for various times, and then cooled, rinsed with water, and dried in air. Corrosion resistance in the surface treated specimens was evaluated by salt immersion test using 1 % NaCl solution as a time for occurring filiform corrosion. On an un-treated AZ31 alloy, the time for starting the filiform corrosion was about 1.2 ks, while on the surface treated specimen, the time was prolonged into about 1300 ks. Moreover, the surface treated specimen showed corrosion resistance in low pH solutions, such as 1 % HNO3 and HCl solutions.
Progress of Directional Solidification in Processing of Advanced Materials
Authors: Fu Heng Zhi , Liu Lin
Published: March 2009

Most of materials have long been considered to be mechanical and/or physical anisotropy. Permitting materials to grow along specific orientation by means of directional solidification technique can optimize their structural or functional properties. The present paper attempts to introduce the research work in the field of processing of some advanced materials by innovative directional solidification techniques performed at State Key Laboratory of Solidification Processing and with author’s intended research work. The paper deals with the specific topics on directional solidification of following advanced materials: column and single crystal superalloys under high thermal gradient, Ni-Cu alloys under deep supercooling of the melt, intermetallic compounds with selected preferential crystal orientation, superalloys with container less electromagnetic confinement, high Tc superconducting oxides, high temperature structural ceramics, continuous cast single crystal copper and copper-based composites. The relevant solidification phenomena, such as morphological evolution, phase selection, peritectic reaction and aligned orientation relationship of crystal growth for multi-phases in the processing of directional solidification, are discussed briefly. The trends of developments of directional solidification technique are also prospected.
Precipitation Behavior during Ageing Treatment of a Single Crystal Nickel-Base Superalloy
Authors: Yang D.Y. , Jin Tao , Zhao Na Ru , Wang Zhi , Sun Xiao Feng , Guan Heng Rong , Hu Zhuang Qi
Published: March 2009

The precipitation behavior during ageing treatment of a single crystal nickel-base superalloy was investigated by SEM and TEM. The results showed that tetragonal needle-like σ phase and blocky -W phase precipitated during low temperature ageing treatment after this testing alloy was completely solution heat treated. σ and -W phases robbed of solid solution strengthening alloying element W、Mo in the matrix and degraded high temperature creep rupture property severely. The creep curve of the crystal tested at 1010 °C and 248 MPa exhibited that the steady state creep rate ε was as high as 9.46 × 10-3/h. The creep-rupture life was only 25 hours. -W phase was not formed by decrease of W content properly. A relatively low level of Co could inhibit σ phase precipitation and improve microstructural stability.
Solid Solution Hardening Effect of Ir
Authors: Yamabe-Mitarai Yoko , Maruko Tomohiro , Miyazawa Tomoaki , Morino Tosiyuki
Published: March 2009

Solid solution hardening effects of Ir was investigated to develop high temperature
materials at 2223 K. Pt, Rh, Hf, and Zr were chosen as second elements because their solubility into Ir at 2223 K is over 2at% and the melting temperatures of Ir solid solution are above 2273 K. Compressive strength of Ir solid solution at 2223K were investigated. Solid solution hardening effect of Ir is discussed in terms of lattice parameter change and solubility,
Metal-Assisted Chemical Etching of Multicrystalline Silicon in HF/ Na2S2O8 Produces Porous Silicon
Authors: Hadjersi T. , Gabouze N. , Ababou A. , Boumaour M. , Chergui W. , Cheraga H. , Belhouse S. , Djeghri A.
Published: March 2009

A new metal-assisted chemical etching method using Na2S2O8 as an oxidant is proposed to form a porous layer on a multicrystalline silicon (mc-Si). This method does not need an external bias and enables formation of uniform porous silicon layers, more rapidly than the conventional stain etching method. A thin layer of Pd is deposited on the mc-Si surface prior to immersion in a solution of HF and Na2S2O8. The characterisations of etched layer formed by this method as a function of etching time were investigated by scanning electron microscopy, X-ray diffraction (XRD), Energy-dispersive X-ray (EDX) and reflectance spectroscopy. It shows that the surface is porous and the etching is independent of grain orientation. In addition, reflectance measurements made with a variety of etching conditions show a lowering of the reflectance from 25 % to 6 % measured with respect to the bare as-cut substrate. However, this result can be improved by changing the experimental conditions (concentration, time, temperature, …).
Raman Microscopy Investigations and Electrical Characterisation of Indentation-Induced Phase Transformations in Silicon
Authors: Khayyat Maha M. , Hasko David G. , Chaudhri M. Munawar
Published: March 2009

Indentation-induced structural phase transitions in single crystal Si(100) and
amorphous silicon a-Si have been investigated for indentations made at room temperature and at 77 K. The experimental techniques employed were (1) Raman microscopy and (2) in situ electrical resistance measurement of the indentation region of the plastically deformed silicon. The Raman spectra from residual indentations revealed that although phase transitions did occur when indentations were made at room temperature, there were no phase transitions when indentations were made at 77 K. This difference in behaviour has been explained on the rise of
temperature during the room temperature indentations, which may assist the phase transition process. The in situ electrical measurements have revealed that the deformed Si(100) yielded Ohmic behaviour, consistent with the view that during the indentation the cubic silicon transforms to the beta-Sn metallic phase (i.e. body-centre tetragonal).
Non-Destructive Observation of Damage Processes in Loaded High Ductile Specimens with Different Crack Configuration by X-Ray Dynamic Defectoscopy
Authors: Vavřík D. , Jakůbek J. , Pospíšil S. , Visschers J.
Published: March 2009

This work reports on the results of the experimental observation of development and
evolution of material damage during loading processes in aluminium alloy flat specimens with different pre-crack configurations by means of the new “X-ray Dynamic Defectoscopy” technique and by plastic strain increments identified by the optical Method of Interpolated Ellipses on the its surface. We have acquired good knowledge about the evolution of damage zone during loading. The
dependence of intensity and shape of damage zone on the crack configuration, part of the field previously little investigated experimentally, has been determined.
Bioimpedance Spectra of Small Particles in Liquid Solutions: Mathematical Modeling of Erythrocyte Rouleaux in Human Blood
Authors: Zehe A. , Ramírez A. , Starostenko O. , Sánchez Adolfo
Published: March 2009

For the modeling of erythrocyte rouleaux we develop an approximation
procedure for the dipole moment in short cylinders, which contains the case of
ellipsoidal bodies only as a first approximation, but allows to include corrections
for short cylinders, more representative for such particles. In dependence on the
number of erythrocytes forming an aggregation, i.e. on different but discrete
measures of rouleaux lengths, the dielectrophoretic force is calculated and
represented against the frequency of the applied a.c. field. Predictions of
frequency regions in the range of 107 to 108 Hz are made, where the amount and
the direction of dielectrophoresis forces is different for different rouleaux sizes.
Prediction of Polymer Molecular Weight Distribution from Rheology: Polydimethylsiloxane Blends
Authors: Llorens J. , Rudé E. , Marcos R.M.
Published: March 2009

We apply a model that connects rheological properties of linear polymer blends with their molecular weight distributions (MWDs). The model is based on the assumption that the relaxation time, ti, of a chain depends on an average molecular weight, M, which determines the effect of the environment where the molecule reptates, and its own molecular weight according to ti = (kE / 0 N G )·M 3.4 - b·Mi b where kE is the constant of proportionality between zero shear viscosity, ho, and weight average molecular weight, Mw, in unimodal polydisperse systems and 0 N G is the plateau modulus. We deduce that the MWD is related to the relaxation spectrum as H(t) = ( 0 N G /b)·M·W(M). Therefore, the MWD is obtained from the relaxation spectrum, which is deduced from the dynamic moduli, G’(w) and G’’(w), constrained by the plateau modulus, the zero shear viscosity and the steady state compliance, 0 e J . The maximum entropy method has been used to solve the integral equation that provides the relaxation spectra from experimental dynamic moduli. The model has been tested in polydimethylsiloxane blends with weight average molecular weight ranging from 94 to 630 kDa and polydispersity from 1.5 to 3.3. Good agreement is found between experimental and calculated MWDs.
XRD and Photoluminescence Studies of Pure and In2O3 Doped ZnO Nanophases
Authors: Boulares N. , Guergouri K. , Tabet Nouar , Lusson A. , Sibieude F. , Monty Claude J.A.
Published: March 2009

ZnO oxide is a promising material for optoelectronics because of its wide and direct gap (Eg=3.4 eV). Pure and doped zinc oxide powders of various grain sizes have been synthesized by vaporisation-condensation method using a solar furnace. The initial powders contained from 0 to 5 In2O3 mol % . X-ray diffraction technique (XRD) has been used to measure the lattice parameter and the grain size as a function of the composition, the results show the appearance of the spinel phase Zn5In2O8 in the micopowders and the decrease of the grain size of nanopowders as the In concentration increases for all considered compositions. The photoluminescence spectra revealed the presence of two main transitions at 3.31 and 3.36 eV, a shift of the excitonic peaks towards the lower energies, a drastic reduction of the exciton bound to donor emission from the doped material and a large broadening of the excitonic emission in In doped nanopowder.
Characterization by Electron Diffraction of Two Thermodynamical Phases of Precipitation in Nb-Microalloyed Steels
Authors: Gómez Manuel , Medina S.F. , Valles Pilar , Quispe Alberto
Published: March 2009

Excellent mechanical properties (high strength and toughness) of microalloyed steels are mainly caused by induced precipitation during thermomechanical treatment (TMT) and grain refinement. It has been recently found that TMT of Nb-microalloyed steels can give rise to two different kinds of precipitates, manifested by the double plateau in the statically recrystallised fraction (Xa) against time curves. This work presents an electron diffraction study performed in a transmission electron microscope, equipped with an EDS analytical system. Lattice parameters of a great deal of particles, smaller than 200 nm and with face cubic centred structure, have been measured. Frequency distribution of the values of lattice parameters shows that these are grouped in two sets whose mean values are close. Comparison of these values with those found in the literature for carbides, nitrides and carbonitrides usually present in microalloyed steels demonstrates that they are Nb carbonitrides with slight stoichiometric differences (NbCxNy).