bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Binders on the Magnetic Behavior of P/M Processed FeSiBCuNb Alloy
Authors: Kim Hee Jin , Song Yong Sul , Park Won Wook , Sohn Keun Yong
Published: March 2009

The effect of heat treatment and binder additions on the magnetic behavior of P/M(powder metallurgy) processed Fe73.5Si13.5B9Cu1Nb3 alloy has been investigated. FeSiBCuNb amorphous ribbons produced by plannar flow casting were annealed at temperatures between 480°C and 620°C for 20 to 60 minutes. The annealed specimens were milled using a pin crusher and a hammer mill. The powder was then mixed with mineral or polymer binders to press into a toroidal shape of inductor core at room temperature. Fe73.5Si13.5B9Cu1Nb3 alloy showed maximum permeability when annealed at 540°C for 40 minutes. The microstructure of the annealed ribbon has a ultra-fine α-Fe(Si) grain, ranging from 10 to 20 nm in diameter. Inductor cores produced using a glass binder showed better magnetic properties than polymers or oxide binders. The use of mineral binders in producing
nanocrystalline inductor cores significantly improved magnetic properties, compared to a commercial moly-permalloy powder core.
Effect of Growth Condition on the Electrical and Magnetic Properties of Sputtered ZnCo2O4 Films
Authors: Kim Hyun Jung , Song In Chang , Sim Jae Ho , Kim Hyo Jin , Kim Do Jin , Ihm Young Eon , Choo Woong Kil
Published: March 2009

We report on the effect of the oxygen partial pressure ratio in the sputtering gas mixture on the electrical and magnetic properties of cubic spinel ZnCo2O4 thin films grown by reactive magnetron sputtering. The conduction type and carrier concentration in ZnCo2O4 films were found to be dependent on the oxygen partial pressure ratio. The maximum electron and hole concentration at 300 K were estimated to be as high as 1.37 × 1020 cm-3 and 2.81 × 1020 cm-3, respectively. While an antiferromagnetic coupling was found for n-type ZnCo2O4, a ferromagnetic interaction was observable in p-type ZnCo2O4, indicating hole-induced ferromagnetic transition in spinel ZnCo2O4.
Effects of Heat Treatment and Alloying of Spheroidal Graphite Cast Iron on Corrosion Resistance in Aqueous Environment
Authors: Aoyama M. , Tahashi K. , Matsuno K.
Published: March 2009

The present study examined the effects of heat treatment and the addition of Cu-Ni alloy on the corrosion resistance of the matrix of spheroidal graphite cast iron in aqueous environments. Test materials of white cast iron and carbon steel were used for comparison with spheroidal graphite cast iron. The alloy spheroidal graphite cast iron that added Cu and Ni was prepared. The spheroidal graphite cast iron was subjected to three kinds of heat treatment to adjust the matrix: annealing, oil
quenching, and austemper heat treatment. In electrochemical tests, measurements of corrosion electrode potential and cathode and anode polarization were used. The following was clarified from the relationship between the electrode potential and current density of each of the materials in each of the solution. The alloy spheroidal graphite cast iron had a high corrosion electrode potential owing to
the addition of Cu-Ni, and tended to have a low corrosion current density. This demonstrates that in any of the materials having a matrix adjusted by heat treatment, the addition of Cu-Ni increased the corrosion resistance. The corrosion current density was highest in a sulfuric acid environment.
Precipitation Behavior of Mg-Y-Nd-Zr Alloy
Authors: Kim In Bae , Hong Jin Young , Hong Bong Gil , Kim Kyung Hyun
Published: March 2009

The precipitation behavior of Mg-Y-Nd-Zr alloy was investigated by using transmission electron microscopy. The precipitation sequence of Mg-Y-Nd-Zr alloy was confirmed as follows ; Supersaturated solid solution → β''→ β'→ β.The β'' phase was identified Mg3Nd having DO19 structure with the lattice constant of a=2aMg=0.64nm and c=cMg=0.52nm. The β' precipitate was identified as Mg12NdY having base centered orthorhombic structure with the lattice constants a, b and c of 0.64, 2.23 and 0.52 nm, respectively. The β phase was confirmed as equilibrium phase having the fcc structure with the lattice constant of a=2.22 nm.
Fabrication of Magnesium Alloy (AZ31) Sheet by Extrusion
Authors: Song Jae Wan , Han Jeong Whan , Kim Mok Soon , Hwang Sun Keun
Published: March 2009

In order to investigate the extrusion characteristics of magnesium alloy (AZ31), a
computer simulation was attempted. Tensile properties of as-cast billet with different strain rates were incorporated into the simulation. The results showed a great change in distribution of stress and strain at near die region by the ram travel. It was found that the average gain size at longitudinal edge of the extruded sheet was smaller than that at center region, which might be attributed to recrystallization caused by severe plastic deformation.
Damping and Mechanical Properties of (Graphite + 9Al2O3·2B2O3)/Mg Metal Matrix Composites
Authors: Choi Il Dong , Kim Dong Min , Cho Kyung Mok , Park Ik Min
Published: March 2009

Mg alloys have potential to use automotive parts because of their weight and castability. High temperature strength and damping capacity is important to the automotive power train parts. Mg alloy has lower creep and thermal fatique strength but has better damping capacity than Al alloy. It is known that short fiber reinforced Mg metal matrix composites(MMC) exhibits superior high temperature strength and graphite reinforced Mg MMC shows excellent damping capacity. Therefore, in this study, the effect of graphite particles(15-25%) and alborex (9Al2O3ּ2B2O3) whiskers(5-15%) on the damping behavior and mechanical properties of Mg MMC was studied. Graphite particles and alborex whiskers were chosen to increase damping capacity and high temperature strength, respectively. The Mg MMC was fabricated by squeeze casting and the total quantity of reinforcements(graphite + alborex) was maintained to 30 volume percent. The damping capacity of the metal matrix composites was increased and the flexural strength and hardness were decreased with increasing the volume fraction of graphite particles, that is, reducing the volume fraction of alborex whiskers.
Anelastic Properties of Polycrystalline Copper
Authors: Kang Chang Seog , Hong Sung Kil
Published: March 2009

An attempt has been made to measure the temperature dependence of dynamic Young's modulus together with the related variation of internal friction in polycrystalline copper. A mechanical spectroscopy study was used a standard servo hydraulic fatigue testing machine equipped with a scanning laser extensometer. Dynamic Young’s modulus and internal friction are measured over a temperature range of 298 to 873K at very low frequencies of 0.1, 0.05 and 0.01Hz. One internal friction peak was observed over the ranges 450K to 700K, together with marked decreases in the dynamic Young.s modulus in the same temperature ranges. From a quantitative analysis of the experimental data with the relaxation strength, relaxation time and activation energy, it is concluded that the peak phenomenon is due to grain-boundary sliding relaxation.
In-Situ Fabrication and Microstructure of Alumina-Zirconia Layered Rolling Bearing in Aqueous System
Authors: Lee Jae Ean , Kim Jae Won , Jung Yeon-Gil , Koo Bon Heun , Lee Hee Soo
Published: March 2009

Bilayer with inner layer of ZrO2-3mol% Y2O3 (TZ-3Y) and outer layer of zirconiaalumina (AKP-30) composite is fabricated using gel-casting for the inner layer and dip coating for the outer layer in aqueous system. The processing additives for gel-casting, such as dispersant, monomer, dimmer, and initiator, are adjusted and optimized. From which the solid loading of each starting material is determined. The bilayer structure can be in-situ formed by dip coating, which are verified by the sintered microstructure of the bilayer investigated.
Strength and Toughness of Graphite Materials for Solid Rocket Motor
Authors: Nambu Shoichi , Enoki Manabu
Published: March 2009

It was pointed out that one of the causes of recent failure to launch rocket was due to the fracture of nozzle throat insert made of graphite materials. The relationship between mechanical properties and microfracture process in graphite was not enough analyzed. To ensure the reliability of such aerospace equipment, we considered the necessity of assurance by non-destructive evaluation, evaluation of mechanical property for graphite material and design based on fracture probability. In this study, four-point bending test and fracture toughness test were used to evaluate mechanical properties. Mean strength, Weibull parameters, and R-curve for crack propagation were estimated. AE measurement during tests was performed in order to obtain location and stress of microfracture. AE results were analyzed by stochastic process theory. The result of AE demonstrates that microfracture process during bending test is divided into three stages. AE behavior in fracture toughness test was also closely related to crack propagation.
Characteristics of Fine WO3 Prepared by Emulsion Evaporation Methods
Authors: Ahn Jong Gwan , Kim Dong Jin , Shin Chang Hun , Lee Man Seung
Published: March 2009

Spherical fine powders of tungsten oxide were prepared by emulsion evaporation method. The characteristics of the powders prepared were examined by means of TGA, XRD, SEM and image analyzer. The emulsions were prepared by vigorous mixing of aqueous phase containing tungsten ion and the organic phase containing kerosene, surfactant and paraffin oil. Precursors were made by evaporating the emulsion in the kerosene bath at 160 °C and then calcined at 650 °C. The average particle size of the tungsten oxide powders was 0.6 ㎛ and their shapes were spherical. As the HLB value of the surfactant increased and the concentration of tungsten ions decreased, the mean particle size of tungsten oxide powders decreased whereas agglomeration size increased
Phase Behavior of La1-xMnO3-1.5x with Trivalent Manganese Ion
Authors: Kobayashi M. , Sato Hirohisa , Kamegashira Naoki
Published: March 2009

Defect perovskite, La1-xMnO3-1.5x (x=0.00-0.10), was synthesized by conventional ceramic method and phase transition was measured by X-ray diffractometry, electrical conductivity, thermal diffusivity and thermal analysis. La1-xMnO3-1.5x (x=0.00-0.09) have single orthorhombic phase corresponding to GdFeO3 type perovskite structure at room temperature, while have rhombohedral structural at high temperature. The transition temperatures observed from electric conductivity, DSC, thermal diffusivity were mostly in agreement and they slightly decrease with increasing x.
Residual Stress Distribution in Graded PSZ/Inconel Composite Deposited by Particle Collision
Authors: Seo Do Won
Published: March 2009

Interfacial strength distribution and thermal residual stresses in multi-layered or
compositionally graded NiCrAlY/ZrO2 coatings are analyzed. These coatings are fabricated by detonation gun spraying using mechanically alloyed, plasma-spheroidized composite powders. The problems in design of functionally graded materials (FGMs) are outlined and their modeling approaches are reviewed. Due to the concentrational or structural gradients in FGMs, the normal approximations and models, used for traditional composites, are not directly applicable to graded materials. The goal is to show the efficiency of the simplest models to provide the most accurate estimates of the properties and even to make simple elasto-plastic analysis of FGM components without vast computations by finite element methods with an arbitrary non-linear distribution of phases and corresponding properties is presented. Results showed that bonding strengths increased gradually with increase of the composition of metals in the FGM coatings. The FGM coating was more stable on the mechanical properties than normal duplex composites. And, the maximum compressive radial stress is found to be at or near the surface of the specimen where surface cracking may be generated. The maximum axial stress is at the edge of the specimen where spallation may occur. The maximum shear stress is also at or close to the edge.
Oxidation of (Al+8%Mn)3Ti Intermetallics Synthesized by Mechanical Alloying
Authors: Jang Y.D. , Kim Sung Jin , Lee Dong Bok
Published: March 2009

The oxidation behavior of (Al+8 at.%Mn)3Ti alloys prepared by mechanical alloying followed by cold isostatic pressing and sintering at high temperatures was investigated at 1000 and 1100°C up to 300 hr in air. Since the Al2O3 barrier layer having some dissolved ions of Ti, and Mn formed, the oxidation resistance of the prepared alloys was excellent.
Properties Evaluation of Composites Including Cracked Ellipsoidal Inhomogeneity
Authors: Lee Bong Ju , Yoon Duck Young , Cho Young Tae
Published: March 2009

In particle or short-fiber reinforced composites, cracking of reinforcements is a
significant damage mode because the cracked reinforcements lose load carrying capacity. This paper deals with elastic stress distributions and load carrying capacity of intact and cracked ellipsoidal inhomogeneities. Axisymmetric finite element analysis has been carried out on intact and cracked ellipsoidal nhomogeneities in an infinite body under uniaxial tension. For the intact inhomogeneity, as well known as Eshelby’s solution, the stress distribution is uniform in the inhomogeneity and nonuniform in the surrounding matrix [1-3]. On the other hand, for the cracked inhomogeneity, the stress in the region near the crack surface is considerably released and the stress distribution becomes more complex. The average stress in the inhomogeneity represents its load carrying capacity, and the difference between the average stresses of the intact and cracked inhomogeneities indicates the loss of load carrying capacity due to cracking amage. The load carrying capacity of the cracked inhomogeneity is expressed in terms of the average stress of the intact inhomogeneity and some coefficients. It is found that a cracked inhomogeneity with high aspect ratio still maintains higher load carrying capacity than one with low aspect ratio.
Holographic Recording in Congruent LiNbO3 Co-Doped with Tb and Fe
Authors: Shin Hyun Kwon , Lee Sang Goo , Lee Myeong Kyu
Published: March 2009

We have preformed holographic recording in congruent LiNbO3 doped with Tb and Fe
with a continuous-wave green laser at λ = 532 nm. This material exhibited a fast coloration upon
exposure to ultraviolet (UV) light. The recording sensitivity was improved from about 0.02 cm/J
to over 0.08 cm/J after UV pre-exposure, due to the increased visible absorption. Holograms
recorded from the colored state could be quickly erased by UV illumination and a sequence of
recording by green and erasure by UV could be continuously repeated without any noticeable
degradation in maximum diffraction efficiency or sensitivity. The overall performances of this
crystal relevant to holographic storage are here presented, in comparison to those obtained with
near-stoichiometric LiNbO3:Tb,Fe.
Characteristics of SnO2 Thin Films Deposited by RF Magnetron Sputtering
Authors: Ryu Hyun Wook , Park Yong Joo , Noh Hyo Sup , Park Jin Seong
Published: March 2009

SnO2 thin films were prepared on SiO2/Si substrate by RF-Magentron Sputtering method,
varying the deposition time and Ar-to-O2 flow ratio. The post-annealing was conducted at 500 oC
and 700 oC in Ar and O2 atmosphere, respectively. Film characteristics were very sensitive to the
gas flow ratio during the deposition and the conditions of post-annealing. The Film thickness
decreased with decreasing of Ar flow ratio at a constant amount (50 sccm) of total gas flow.
Especially, the film deposited under Ar-O2 mixture gas (Ar-to-O2 ratio of 50%) showed clearly
aggregated morphology of small particles (cauliflower) in a wide range of area. In the annealed
films, these cauliflowers separated some small grains, decreasing the film thickness.
Isotope Effects on Hydrogen-Related Bound Exciton Spectra in SiC
Authors: Bai Song , Choyke Wolfgang J. , Devaty Robert P.
Published: March 2009

We report isotope shifts of the no-phonon lines of VSi+H/D complexes observed in lowtemperature photoluminescence spectra of proton/deuteron implanted and annealed samplesshowing both the hydrogen and deuterium spectra. We propose that the isotope shift of the nophonon lines is related to the zero-point energies of the vibrations in both the electronic ground andexcited states of the complex. The red shift of the deuterium no phonon line with respect to thehydrogen line is consistent with a stiffer spring constant for the potential well associated with theexcited state. We tentatively assign a weak shoulder on the Hs3 first harmonic line to the 13C isotope.
Modelling Zener Pinning: A Comparison of Different Computer Simulation Methods
Authors: Harun Azmir , Miodownik Mark A. , Clode Mike P. , Holm Elizabeth A.
Published: March 2009

We compare the ability of three different types of microstructural model to simulate particle pinning. The microstructural models are the Phase Field model, the Front Tracking model and the Monte Carlo Potts model. The same 3D test geometry is simulated using each method. This is an hexagonal network with spherical particles located at the centre of each hexagonal grain. The hexagonal grain network provides a constant driving force for a moving boundary and includes triple line and quadruple point motion. This geometry allows detailed investigation of the boundary/particle interaction. The pinning force acting on the migrating curved grain boundary is calculated and compared with theoretical predictions for each model.
Introducing Solute Drag in Irregular Cellular Automata Modeling of Grain Growth
Authors: Janssens Koenraad G.F. , Holm Elizabeth A. , Foiles Stephen M.
Published: March 2009

In this paper we discuss the principles of a combined approach to solve the problem of solute drag as it occurs in microstructure evolution processes such as grain growth, recrystallization and phase transformation. A recently developed irregular grid cellular automaton is used to simulate normal grain growth, in which the energy of the grain boundaries is the driving force. A new, discrete diffusion model is used to simulate solute segregation to the grain boundaries. The local concentration of the solute is then taken into account in the calculation of the local grain boundary mobility and/or grain boundary energy, thereby constituting a drag force. The relation between solute concentration and grain boundary mobility/energy is derived from molecular dynamics simulations.
The Von Neumann-Mullins Theory of Grain Growth – Valid or Not?!
Authors: Shvindlerman Lasar S. , Gottstein Günter , Rollett Anthony D.
Published: March 2009

We present a new analysis of the relative rate of growth or shrinkage of grains in a two-dimensional network, based on the classical Von Neumann-Mullins (VN-M) analysis. We find that an analysis of the stability of the grain shape during shrinkage or growth shows that any change in the regular 2D grain leads to changes in the shape. We also re-examine a recent analysis that claims to have invalidated the VN-M relationship, but find that it is still valid, and that the cited analysis, in fact, confused a second order correction with a first order problem, partly because their derivation was in error. The erroneous magnitude of the discrepancy led them to use unphysical issues to explain the discrepancy. The way in which the curvature is distributed along the perimeter of a grain only gives rise only to second order corrections to the rate of change of area as a function of grain topology (number of sides).
Computer Simulations and Statistical Theory of Normal Grain Growth in Two and Three Dimensions
Authors: Zöllner Dana , Streitenberger Peter
Published: March 2009

A modified Monte Carlo algorithm for single-phase normal grain growth is presented,
which allows one to simulate the time development of the microstructure of very large grain ensembles in two and three dimensions. The emphasis of the present work lies on the investigation of the interrelation between the local geometric properties of the grain network and the grain size distribution in the quasi-stationary self-similar growth regime. It is found that the topological size correlations between neighbouring grains and the resulting average statistical growth law both in two and three dimensions deviate strongly from the assumptions underlying the classical Lifshitz- Sloyzov-Hillert theory. The average local geometric properties of the simulated grain structures are used in a statistical mean-field theory to calculate the grain size distribution functions analytically. By comparison of the theoretical results with the simulated grain size distributions it is shown how far normal grain growth in two and three dimensions can successfully be described by a mean-field theory and how stochastic fluctuations in the average growth law must be taken into account.
Geometric Dynamic Recrystallization in α-Zirconium at Elevated Temperatures
Authors: Barrabes S.R. , Kassner M.E. , Pérez-Prado Maria Teresa , Evangelista E.
Published: March 2009

The micron-size grain refinement of pure a-zirconium obtained with elevated temperature tensile deformation was investigated. The development of low-misorientation subboundaries caused the serration of the original grain boundaries at low strains. The final microstructure (e.g. strains > 3) was predominantly composed of fine, equiaxed “crystallites” with ⅔ of the boundaries being of very low misorientations (< 3°) and the remaining ⅓ being high angle boundaries (θ > 8°, and typically 25-35°). Discontinuous dynamic recrystallization was excluded as a possible mechanism due to the absence of newly formed grain nuclei. The bimodal distribution of the crystallite or (sub)grain boundary misorientations is inconsistent with the occurrence of continuous dynamic recrystallization and rotational recrystallization. The continual thinning of the original grains, the serration of the high angle boundaries, the bimodal misorientation distribution of misorientations, ⅔ of boundaries of very low misorientations at high strains all strongly suggest geometric dynamic recrystallization and dynamic recovery as the grain refinement and restoration mechanisms.
Recrystallization and Grain Growth in Al-Li Alloys Subjected to Severe Plastic Deformation
Authors: Mizera Jaroslaw , Lewandowska Małgorzata , Adamczyk-Cieślak Bogusława , Kurzydlowski Krzysztof Jan
Published: March 2009

Equal channel angular extrusion (ECAE) was used to obtain ultrafine grain structures in two aluminium- lithium alloys. The specimens were subjected to severe plastic deformation up to strain value of 9,2 at room temperature. After ECAE deformation, the grain size was reduced from an initial value of 300 µm to 1 µm.
The main purpose of this study was to examine the recrystallization characteristics of ECAE treated specimens at temperatures of T = 0,5 and T = 0,7 Tm. At each temperature the specimens were heated for 1, 10, 100 seconds. The microstructure, texture and microhardness were examined in the as-deformed condition and after the annealing. The TEM observations indicate that in the Al-0.7 wt. % Li and Al-1.6 wt. % Li alloys, recrystallization has a continuous character. The microhardness results show that the lithium content increases, in an essential way, the mechanical properties of the alloys after severe plastic deformation and subsequent annealing. During ECAE process, a well pronounced texture with the
orientation of the (441)[ 12 4 ], (145)[ 7 31] and (321)[ 3 4 6 ] types are formed within about ¼ volume of the material. After the annealing the grains acquire orientations other than those observed typically in these alloys when deformed by classical straining techniques followed by recrystallization.
Recrystallization Texture and Microstructure in Ni and AlMg1Mn1 Determined with High-Energy Synchrotron Radiation
Authors: Klein Helmut , Preusser Andrea , Bunge Hans Joachim , Raue Lars
Published: March 2009

The newly developed “sweeping detector” technique with high energy synchrotron radiation allows to measure textures and microstructures of materials with high location and orientation resolution. This method was applied to hot rolled aluminium manganese alloys and to rolled nickel samples in different recrystallization stages. The grain-resolved measurements show, impressively, many details of the recrystallization process which can otherwise not be seen. That can be the base for comprehensive recrystallization theories.
The Potential of Combined In-Situ Heating Experiments and Detailed EBSD Analysis in the Investigation of Grain Scale Processes such as Recrystallization and Phase Transformation
Authors: Piazolo Sandra , Seward Gareth G.E. , Seaton Nick , Prior David J.
Published: March 2009

Experiments in which the microstructural development can be observed at the same time as the crystallography is described fully opens up new, powerful ways to advance our understanding of microstructural processes such as grain growth, primary and secondary recrystallization and phase transformations. In addition, comparison of results of experiments in different materials can be used to develop general laws for the investigated processes. In this study, we briefly review and compare the results from various ongoing studies undertaken in a variety of
materials with emphasis on highlighting (a) the scientific potential of such experiments and (b)similarities and differences in their microstructural evolution. Materials studied include metals e.g. Ti, Ni, Al, Mg, Ti-SULC steel and geological materials such as rocksalt (NaCl), hematite and magnetite. Here, we present experimental results and their interpretation in terms of subgrain to grain-scale processes.
Determination of the Recovery Kinetics during the Annealing of Cold Rolled Low Carbon Steels
Authors: Martínez-de-Guereñu Ane , Arizti F. , Gutiérrez Isabel
Published: March 2009

A cold rolled low carbon steel has been annealed at sufficiently low temperatures (300 to 500 °C) in order to promote recovery without interaction with recrystallization. The recovery kinetics has been followed by using magnetic coercive field (Hc) measurements. The microstructural changes associated with the observed decrease in Hc, produced by the recovery, have been analysed
by TEM observations. The experimental data have been adequately modelled using various formulations reported in the literature. The kinetics of the dislocation hardening contribution to the yield stress has been derived from the kinetics of the coercive field, taking into account the existing linear relationship between both variables.
Study of Texture and Recrystallization in Wire Steel
Authors: Boumerzoug Zakaria , Lahraki N. , Zidani Mosbah
Published: March 2009

The operation which allows reducing wire diameter is called wiredrawing. The
wiredrawing principle is that of using the metal plasticity to reduce the wire diameter. Our study is based on wire steel containing 0.05 % carbon. The regular orientation of the grains (texture) caused by external stresses during the drawing process is observed. This texture causes a phenomenon of material consolidation. Two annealing temperatures were applied on deformed wires for modifying the structure and mechanical properties. The effects of drawing and thermal treatment on our
material were studied by, scanning electron microscope, hardness measurements and X – ray diffraction.
Grain Refinement and Texture Change in Interstitial Free Steels after Severe Rolling and Ultra-Short Annealing
Authors: Kestens Leo , Reis Ana Carmen C. , Kaluba Wlodzimierz , Houbaert Yvan
Published: March 2009

A Ti-stabilized interstitial free steel was highly cold deformed to a reduction of 95% and subsequently submitted to extremely short annealing cycles with heating rates varying between 300°C/s and 4500°C/s followed by water quench at various temperatures. The microstructural and textural development was studied through various consecutive stages: partially recrystallized, fully recrystallized and after α→γ→α transformation. It was found that irrespective of the heating rate the recrystallization has completely terminated before the onset of the ferrite to austenite phase transformation. In the fully recrystallized condition, ultra-rapid heating gave rise to substantially refined structures with an average ferrite grain size of 6µm. It was also observed that this grain refinement saturates with heating rates beyond 1000°C/s. With regard to the texture formation, the characteristic {111} deep drawing fibre of cold rolled IF steels was observed, irrespective of the heating rate, in an annealing treatment as short as 0.3s. After the forward and reverse α→γ transformation, the ensuing ferrite texture displayed a strong memory
effect, as the {111} fibre was even more intense after the double transformation than before.
Evaluation of Stored Energy in Cold-Rolled IF Steels from EBSD Data and Its Application to Recrystallization Modeling
Authors: Choi Shi Hoon , Chin Kwang Geun
Published: March 2009

This study has been conducted to evaluate the orientation-dependent stored energy of deformed grains from the data measured using electron back-scattered diffraction (EBSD) analysis. The stored energy in deformed grains is an important term as a driving force for static recrystallization of cold-rolled steels. Subgrain method based on subgrain structure is used for quantitative analysis of the stored energy developed in cold-rolled interstitial free (IF) steels to a reduction of 80%. The orientation dependent stored energy term was used in Monte Carlo technique to simulate static recrystallization of IF steels.
Experimental Investigations of Recrystallization Texture Development in Zirconium (Zr702)
Authors: Dewobroto N. , Bozzolo Nathalie , Barbéris Pierre , Wagner Francis
Published: March 2009

The microstructure and crystallographic texture in zirconium (Zr702) sheets, initially deformed by 80% cold rolling, are investigated at different stages of the primary recrystallization. Inhomogeneities were observed in the deformed microstructure at different scales down to the submicrometer range. The influence of these inhomogeneities on the local recrystallization mechanisms is discussed. The measurement of the orientation of the new grains shows that the nucleation is definitely not oriented. Since the global texture change is very slight, recrystallization by subgrain growth is probably one of the most important mechanism during the recrystallization process in zirconium.
Structure Evolution of Zirconium Alloys during Deformation/Heat Treatment
Authors: Nikulin Sergey A. , Rojnov A.B. , Peregud M.M.
Published: March 2009

Using transmission electron microscopy, x – ray diffraction analysis, tensile
testing and fractography the changes were analyzed that occur in microstructure and tensile properties of E635 alloy annealed after quenching from b – region of phase diagram. The interrelation is demonstrated between microstructure and tensile properties depending on deformation/heat treatment conditions.
Microstructure and Texture Development during Recrystallization of Rolled Molybdenum Sheets
Authors: Hünsche I. , Oertel C.G. , Tamm R. , Skrotzki Werner , Knabl W.
Published: March 2009

Recrystallization is an important tool to adjust the grain size and texture of polycrystalline materials in order to optimize their properties. In the present work recrystallization and the related changes of texture have been studied on rolled molybdenum sheets as a function of temperature and time. The microstructure was investigated by orientation contrast in a scanning electron microscope. The kinetics of recrystallization displayed in a JMAK plot yields Avrami coefficients decreasing with temperature from 2.5 to 1.1. The activation energy amounts to 5 eV, which agrees well with the volume self-diffusion coefficient. The textures of the sheet surface and central layer were measured by X-ray diffraction. The rolling texture in the centre of the sheets is characterized by a strong a-fibre with the rotated cube component {100}<110> dominating. Besides that, there exists a weak g-fibre. In contrast, the surface layer is characterized by a weak cube component. During recrystallization changes in texture are insignificant. With long annealing times all texture components tend to degrade. Conclusions regarding the deep-drawability are drawn.
Grain Refinement in Magnesium Alloy AZ31 during Hot Deformation
Authors: Yang Xu Yue , Miura Hiromi , Sakai Taku
Published: March 2009

The deformation behavior and structure changes of magnesium alloy AZ31 were studied in compression at temperatures ranging from 523K to 673K and at a strain rate of 3 x 10-3 s-1. They depend sensitively on deformation temperature. At high temperatures, grain fragmentation takes place due to frequent formation of kink bands initially at corrugated grain boundaries and then in grain interiors, followed by full development of new grains in high strain. At lower temperatures, in contrast, twinning takes place in rather coarse grains and kink bands are formed mainly in finer original ones in low strain. It is concluded that new grain evolution can be controlled by a deformation-induced continuous reaction resulting in grain fragmentation by kink bands, i.e. continuous dynamic recrystallization (cDRX). The latter is discussed comparing with conventional, i.e. discontinuous, DRX.
Monte Carlo Modelling of Recrystallization Mechanisms in Wire-Drawn Copper from EBSD Data
Authors: Gerber Ph. , Tarasiuk Jacek , Solas Denis , Jakani S. , Mathon Marie Helene , Baudin Thierry
Published: March 2009

In order to simulate the recrystallization process, Monte Carlo modelling has been
applied to the case of wire-drawn copper deformed to a moderate strain. The complete experimental set of data was taken mainly from Electron Back Scattered Diffraction measurements in a Scanning Electron Microscope. Several nucleation hypothesis have been introduced and tested into the model. It has been shown that nucleation taking into account the sites associated with the highest stored energy and highest local misorientation leads to the best results in terms of recrystallization
microstructure and texture. An important number of new orientations - that come only from annealing twinning - are not reproduced with the model, indicating the major role of this particular mechanism during the recrystallization process.
Anisotropy of Grain Boundary Migration Observed in Situ by Synchrotron Radiation
Authors: Paidar Václav , Lejček Pavel , Polcarová M. , Brádler J. , Jacques Alain
Published: March 2009

Grain boundary motion was studied in situ at elevated temperatures by x-ray topography using synchrotron radiation. In addition to the position of grain boundary, other crystal defects that may interact with the moving boundary were observed simultaneously. Two types of bicrystals with the [001] rotation axis were selected for the experiments, the first one with a high coincidence S5 misorientation of about 37° and the other one with no coincidence of two crystals for the misorientation of 45°. The geometrical differences between chosen bicrystals are examined and attention is also paid to faceting – local orientations of the boundary plane.
A Study on the Vibration Analysis of a Ball Screw Feed Drive System
Authors: Choi Y.H. , Cha S.M. , Hong J.H. , Choi Jai Hyuk
Published: March 2009

Feed drive system of machine tools may experience serious vibrations or unstable motions during high-speed operation. In this paper, a 6 D.O.F (Degree-Of-Freedom) lumped parameter model was proposed in order to analyze vibrations of a ball screw feed-drive system, which takes planar motion. The equations of motion were derived for the proposed model. Natural frequencies of the system and transient responses due to driving motor speed control input were also analyzed. Experimental modal analysis and operational vibration measurements of a laboratory ball screw feed drive system were made. Both theoretical analysis and experimental measurement results showed good agreement with each other. Consequently we concluded that the proposed 6 D.O.F model could be well applicable to the vibration analysis of a ball screw feed-drive system.
Intelligent Error Compensation in CNC Machining through Synergistic Interactions Among Modeling, Sensing and Learning
Authors: Liu Zhan Qiang , Zhang Jun Bo , Tang Zhi Tao
Published: March 2009

Industry is looking for practical means to improve the accuracy of the parts machined on CNC machines. Some artificial intelligence (AI) systems have been applied in modeling and compensating manufacturing process errors in CNC machining. However, these systems are not capable of predicting the results of a new operation if no sufficient data on a number of similar operations is available. A generalized AI approach named synergistic interactions amongst modeling, sensing and learning is proposed in this paper. Based on the AI approach, a new strategy of error compensation of workpiece dimension in CNC machining is developed and applied in a CNC turning center. Error compensation results are illustrated the effectiveness of the error compensation strategy. The learning curve shows that the error compensation confidence gradually progresses towards 100% confidence from zero along with the CNC machine operation time increasing.
Study on Groove Optimization Technology Based on the Power Spectrum Analysis
Authors: Li Zhen Jia , Cheng Yao Nan , Tan Guang Yu , Ning S.Y. , Wang Z.G.
Published: March 2009

Based on the milling force testing system, we have experimented with the waved-edge milling insert and the great milling insert developed by Harbin University of Science and Technology, the American Metal milling insert, the ISCAR hackle milling insert and the flat milling insert, and then compare the insert milling capability of various grooves milling inserts. We have discussed the dynamic milling force under the incontinuous cutting condition, especially the characteristic of time and frequency. Based on the power spectrum analysis of the five types of milling inserts, we have found that the insert whose groove is formed from the curve or curly plane
of the period function has an advantage on minishing the milling force and resisting to vibration. The right insert geometry parameters have great effect on improving the cutting capability. By the power spectrum analysis, we found that the complex 3-D grooves milling insert is superior to the flat milling insert on minishing milling force and vibration. The analysis result proves that using power spectrum analysis in groove optimization is viable.
Development of 3-D Parameterized Design System for Involute Gear Parts
Authors: Gao Hang , Zhao K. , Lu Y.
Published: March 2009

Taking the three-dimensional CAD software Solidworks as developing platform and with the help of its powerful OLE technical support offered, the mathematical model of involute curved surface of bevel gear is established and the 3-D parameterized design and analyzing system for involute gear parts is developed in the paper. By inputting necessary variables on the interface of the gear design system an accurate 3-D parameterized geometric entity of involute gear can be automatically created. In the design system a kind of method called template technique is developed to realize the conversion of a gear part from 3-D geometric entity to corresponding 2-D standard engineering drawing and the marking of necessary design technical requests and parameters on the engineering drawing automatically, which offsets the lack that current three-dimensional CAD software can not automatically create standard two-dimensional CAD engineering drawing. Also the
gear strength checkout program module is developed which is helpful to greatly improve design efficiency of involute gear parts.
Processing and Mechanical Properties of Biphasic Calcium-Phosphate/Poly-L-Lactide Composite Biomaterials
Authors: Tang Chak Yin , Ignjatović N. , Uskokovic Dragan P. , Uskoković P.S. , Chan K.C. , Lo S.C.L. , Lee Tai Chiu
Published: March 2009

This study descripts processing of biphasic calcium-phosphate (BCP) and poly-L-lactide (PLLA) biocomposite implant material. The composite was obtained by mixing completely dissolved PLLA with granules of high crystalline BCP and was compacted by hot pressing using cylindrical dies at 450 K temperature and 98.1 MPa pressure, for 30 and 60 minutes. Wide-angle Xray structural (WAXS) analyses of BCP, PLLA and BCP/PLLA composite blocks were made followed by calorimetric (DSC) tests in the 320-520 K temperature range. Compression tests
revealed that Young’s modulus and compressive strength of the composite increased with extended hot pressing time and were found to be within the bounds of the cortical bone values.
Cutting Forces in Sawing Process of Reinforced Concrete
Authors: Wang Cheng Yong , Hu Ying Ning , Ding H.N.
Published: March 2009

Three kinds of typical concrete materials were tested involving cement concrete, steel fiber reinforced concrete and ferroconcrete. The 3-direction cutting forces acted on the diamond sawblade were measured with varied cutting speed, feed speed, depth of cut and diamond segments. The measurements show that during the whole cutting process, the curve of cutting forces fluctuate intensely, which indicate the differences of the cutting process of heterogeneous mixture of the
concrete. Because of the larger amplitude, the average values of cutting forces are much smaller than that of peak values. The cutting forces increase with the increase of feed speed, in reverse, decrease with the increasing of cutting speed. When the strength grades of the concrete materials are the same, the cutting forces of ferroconcrete and steel fiber reinforced concrete show the higher value than those of cement concrete. The cutting forces of sawblade with brone-cobalt based bond are greater than those of sawblade with cobalt based bond in sawing concrete process. Adding cobalt content in matrix, the cutting force can be decreased when sawing cement concrete. While sawing steel fiber concrete and ferroconcrete, the cutting forces can be decreased by reduction of cobalt content and increase of iron content in matrix.
Precision Finishing Combined with ELID and MRF
Authors: Kang Gui Wen , Zhang Fei Hu , Dong Shen
Published: March 2009

ELID grinding is widely used as a high-productivity and super-precision grinding method for hard and brittle materials. It continues grinding stably with metal bonded diamond wheel due to its in-process dressing. Magnetorheological finishing (MRF) is a novel precision finishing process for hard and brittle materials. In this paper, ELID grinding and MRF are adopted to get high surface quality and remove subsurface damage of hard and brittle materials. The results show that this combination gives attention to both efficiency and quality and can be used to replace conventional optics manufacturing.
Superplastic Bulging of an Al-6Mg-0.3Sc Alloy and Its Forming Limits
Authors: Tong G.Q. , Chan K.C. , Nieh T.G.
Published: March 2009

High strain rate superplastic (HSRS) bulging and cavitation behavior of a cold rolled Al-6Mg-0.3Sc sheet were investigated at the temperature of 798K and at the constant applied flow stress of 6.0MPa. The maximum effective strain of about 2.1 was obtained. The experimental results revealed that the cavity growth was essentially plastic - controlled. HSRS bulging limits of the sheet were further predicted based on the Marchiniak - Kuczynski model and a plastic damage approach. It is able to predict HSRS forming limits of the sheet in a reasonable agreement with the experimental findings even without assuming any initial geometrical defect.
Evaluation on Died-Pressed Binders of Ti(C,N)-Based Cermet Powders
Authors: Fan Chou , Xiong Wei Hao , Wei J. , Feng Ping Fa , Lei Y. , Liang Z.G.
Published: March 2009

The effect of died-pressed binders, such as polyvinyl alcohol (PVA), butyl sodium rubber (BSR) and paraffin wax (PW), on green strength, green density, dimensional stability, residue, sintered compact density and mechanical properties of Ti(C,N)-based cermet was investigated. It was found that the types of the binder had a significant impact on the characteristics of the green compact.
PVA improved dimensional stability of the green compact due to interaction between binder and particle. The glass transition temperature (Tg) of PVA influenced the forming behavior of Ti(C,N)-based cermet powders during died-pressed processing. Some residual moisture was needed to obtain high green strength. PVA had a gradual burnout with a low char residue in nitrogen. Compared with PVA, the influence of binders BSR and PW was also presented and discussed.
Study on Technology of Flexible Forming of Sheet Metal Based on Laser Shock Waves
Authors: Zhang Yong Kang , Zhou Jian Zhong , Zuo Dun Wen , Yang Judith C. , Cai Lan
Published: March 2009

The conventional forming of sheet metal is realized by the Die and Mould, this method usually give rise to high cost, long production periods and little flexibility. In order to adapt to the changing requirements of the market and make small batch production of three-dimensional parts of shallow stretching economically, a flexible forming technique of sheet metal based on laser shock waves is presented in this paper. After the forming mechanism and process are introduced, a finite-element analysis method is applied to simulate the shock forming process to obtain the optimized laser parameters and the shocking tracks. The experimental are carried out for the overlapped shock-forming, and the forming contour is measured and compared with the FEA simulation. The investigation provides the theoretical foundation for the selection of forming locus and processing parameters of flexible forming of sheet metal.
Modelling the Depth of Jet Penetration in Abrasive Waterjet Contouring of Alumina Ceramics
Authors: Wang Jun , Liu H. , Huang Chuan Zhen
Published: March 2009

Predictive mathematical models for the depth of jet penetration are presented for both
straight-slit cutting and contouring by an abrasive waterjet (AWJ). The plausibility and predictive capability of the models are assessed and verified by an experimental investigation when cutting an 87% alumina ceramic. It shows that the predictions of the models are in good agreement with the experimental data.
Research on Ultra-Precision Machining Technology for KTP
Authors: Yuan Ju Long , Lou Fei Yan , Wang Zhi Wei , Chang M. , Du W.P. , De Q.F.
Published: March 2009

Potassium Titanium Oxide Phosphate (KTP) is a new nonlinear frequency-conversion crystal. It has chemical stability, high nonlinear coefficient, high damage threshold, easily-polished surface, and a broad transparency range. It is be used in solid green laser with medium and low power widely. The requirement for surface roughness is less than 1nm.In this paper, the removal rate and surface roughness are discussed with different velocity, pressure and size of abrasive powder. In order to satisfy the requirement, new polishing techniques with ultra-precision plane polishing machine (Nanopoli-100), and fine AL2O3, SiO2 powders are proposed in this study. The final surface roughness of the KTP is less than 1nm.The machining process and characteristics are also indicated.
Design of High Precision Power Supply for Low-Frequency Vibration Cutting
Authors: Jiang X.G. , Zhang D.Y.
Published: March 2009

The frequency of piezoelectric transducer requires high stability and can also be
continuously changed. The voltage requires smooth and stable sine wave. To the two problems, a high precision power supply for vibration cutting is designed. It divides the whole frequency band into several small bands. By means of CPLD, the sine wave is digitally fitted individually at each small band. So the sine wave can be always suitable at a wide frequency band. At the power output, OCL power amplifier is adopted. The output sine voltage becomes smooth and stable by adding voltage negative feedback to the power amplifier. The experiment results show its feasibility.