bluuebunny/crossref_metadata_2025 huggingface dataset:
Orientation Dependence of Dynamic Recrystallization Behavior of Al Single Crystals
Authors: Miura Yasuhiro , Ihara Kentaro
Published: March 2009

An experimental study on the microstructure development and stressstrain behavior during high temperature deformation of aluminum (Al) single crystals was made by using X-ray Laue technique and the electron backscatter pattern (EBSP) technique. The main purpose was to clarify the process of dynamic recrystallization (DRX). The measured stress-strain curves with large stress
peaks and the new Laue spots without streaks at around the stress peaks confirmed the occurrence of DRX in Al single crystals with initial compression axis <111>, <011> or <001>. Crystallographic analysis by the Laue technique and EBSP technique show that the DRX grain and the matrix have an <121> axis in common in the <111> crystal, an <101> axsis in the <011> and <001> crystals. For the <111> crystal, the unrecrystallized region near the DRX grain consists of subgrains adjoined each other with <112> tilt boundaries and the size of subgrains becomes smaller and the misfit at subgrain boundaries becomes larger as the DRX grain boundaries are approached. These results suggest that DRX grains are nucleated through the development of subgrains.
Barrier Ribs of PDP by Injection Molding
Authors: Choi Hak Nyun , Kim Yong Seog
Published: March 2009

Barrier ribs of plasma display panel (PDP) were prepared via injection molding of
thermally curable paste. The paste composition was optimized by considering the effects of powder content, binder type and content on the viscosity of paste. Various types of molds including stripe, honeycomb, and meander were prepared using UV lithography. In this study, main causes ofdimensional change during sintering of meander type barrier ribs produced by injection molding process were investigated by changing powder content in the paste. The results indicated that sintering stress generated in the barrier rib is not balanced at the points where the ribs are curved,
causing dimensional change in the ribs.
Low-Cycle Fatigue Fracture Behavior of Superalloy GH4586 at Elevated Temperature
Authors: Wang Lei , Cui Tong , Lü Jun Ying , Yang Hong Cai , Zhao Guang Pu
Published: March 2009

Low-cycle fatigue property of superalloy GH4586 was investigated using a stress
amplitude-controlled mode at 1023K. Fracture surface was examined with a scanning electronic microscopy. It was found that the cyclic life can be illustrated by Manson-Coffin at all strain levels. The fatigue cracks initiate primarily on the surface of the specimen. The plastic strain amplitude responded to the cyclic loading shows higher sensitivity than that of the elastic strain amplitude. It was demonstrated that the failure of the present alloy is in a manner of creep-fatigue feature.
Plasma Etching for Fabricating the Concave-Type DRAM Capacitors
Authors: Kim Hyoun Woo
Published: March 2009

The usage of barium strontium titanate (BST) capacitor have recently been considered in the fabrication of dynamic random access memory (DRAM) device. In this study, in order to avoid the difficulties of high aspect ratio etching of bottom electrode in the conventional stack-typecapacitor structure, we suggest to introduce a concave-type capacitor structure. The fabrication procedure of the two kinds of the concave capacitor cells, Pt/BST/Pt and Ru/BST/Ru are explained. We have studied on the metal electrode etching in the concave structure and have discussed the patterning issues in fabricating the capacitor structures.
Hydrogen-Induced Degradation and Passivation of Ferroelectric SrBi2Ta2O9 Thin Films by Au Top Electrode
Authors: Choi Hoon Sang , Sung Hyun Joo , Seo Seung Gun , Jang Yu Min , Son Chang Sik , Choi In Hoon
Published: March 2009

We investigated the effects of hydrogen annealing process on ferroelectricity in
SrBi2Ta2O9(SBT) capacitors. The hydrogen-induced degradation of SBT capacitors was found after a hydrogen annealing process. The degraded properties could be recovered by re-crystallization annealing process in O2 ambient for 30 min. In order to prevent the catalyst reaction of Pt electrode known as an origin of hydrogen-induced degradation, Au top electrode was used. It was confirmed
that Au electrode effectively prevented capacitors from degrading during hydrogen process.
Coarsening Kinetics of B2 Precipitate Particles in an Elastically Constrained Fe-Al-Co Alloy
Authors: Maebashi T. , Doi Minoru , Kozakai Takao
Published: March 2009

The morphological changes and the coarsening kinetics of B2 particles in A2 matrix in the elastically constrained Fe-16at%Al-18at%Co alloy were investigated by means of transmission electron microscopy (TEM). The mean particle radius increases in proportion to the cube root of ageing time at early stage, then the coarsening of B2 particle decelerate at late stage of aging. And it clarified the decelerated coarsening in Fe based alloy also is related to the change in PSD and is
caused by the elastically strained effect.
Microstructural Change of Cementite in Carbon Steels by Deformation
Authors: Todaka Yoshikazu , Umemoto Minoru , Tsuchiya Koichi
Published: March 2009

Deformation and dissolution behavior of the cementite in eutectoid steels with pearlitic and spheroidite structures were studied using high resolution SEM and AFM. Cementite lamellae in deformed pearlite exhibited inhomogeneous slip, smooth thinning or necking, fragmentation and cleavage fracture. Complete dissolution of cementite lamellae and spheroidal cementite particles was observed in specimens deformed with large strains at high strain rates. The dissolution mechanism of cementite by heavy deformation was discussed.
Characteristics of Material Degradation for Thermal Aged X20CrMoV12 1 Steel
Authors: Chung Y.K. , Park Jong Jin , Zhang Xinghong , Park Ik Min
Published: March 2009

X20CrMoV12 1 steels were exposed at three different high temperatures and various
durations. Aging parameter, LMP s, was used to describe long-term thermal history. Creep rupture, hardness and tensile tests for aged X20CrMoV12 1 steels were carried out. Yield strength was slightly decreased and hardness was rapidly decreased afterLMP s reached 20.6. Creep strength of aged X20CrMoV12 1 steel decreased rapidly after the LMPs reached 20.6. It was shown that the creep strength decreased due to the coarsening of acicular type M23C6 at subgrain boundaries and the agglomeration of M23C6 at prior austenite grain boundaries. After LMPs reached 20.6, the assumed linear regression line of stress and Larson-Miller parameter,LMPf, also moved toward a
lower LMPf region as aging parameter increased. The dependency of creep rupture life on the microstructural degradation could be represented by CLMPs, which is LMPf at stress of 1 kg/mm2. It was found that the creep rupture life of X20CrMoV12 1 steel could be predicted by considering the material degradation during and prior to creep test.
Critical Strain for the Initiation of Dynamic Recrystallization in a Ni-Fe Base Alloy
Authors: Na Y.S. , Rhyim Young Mok , Lee J.Y. , Lee Jae Ho
Published: March 2009

In order to quantitatively analyze the critical strain for the initiation of dynamic
recrystallization in Ni-Fe-based Alloy 718, a series of uniaxial compression tests was conducted in the temperature range 927°C - 1066°C and the strain rate range 5 x 10-4 s-1 - 5 s-1 with varying initial
grain size. The critical strains were graphically determined based on one parameter approach and microscopically confirmed. The effect of γ'' (matrix-hardening phase) and δ (grain boundary phase)on the critical strain was simply discussed. The constitutive model for the critical strain of Alloy 718 was constructed using the experimental data obtained from the higher strain rate and the temperature
range between 940°C and 1040°C.
Rapid Grain Growth of Hot Extruded Al-Zn-Mg-Cu-(Sc) Alloy during Heat Treatment
Authors: Suh Dong Woo , Lee Sang Yong , Kang Jun Yun , Oh Kyu Hwan
Published: March 2009

Rapid grain growth and artificial aging characteristics during heat treatment is investigated for hot extruded Al-Zn-Mg-Cu-(Sc) alloys. Two Al-0.1wt%Sc alloys with different alloying element content are hot extruded to make T-shape bars at 380°C, and then the bars are solution treated for 2 hours at 480oC followed by artificial aging for 24 hours at 120°C. Microstructural evolution of the hot extruded bar is analyzed with optical microscope and electron back scattered diffraction (EBSD) mapping. Two kind of extruded bar shows different grain growth behavior at surface region and different artificial aging characteristics. The interaction between the precipitates and the grain growth during the heat treatment is thought to be responsible for the different grain growth behavior.
Thermal Properties and Fracture Behavior of Compositionally Graded Al-SiCp Composites
Authors: Cho Kyung Mok , Choi Il Dong , Park Ik Min
Published: March 2009

Compositionally graded Al-SiCp composites were fabricated using pressureless infiltration process. Microstructure was examined and thermal properties were characterized for Al-SiCp composites. Al-SiCp composites with fairly uniform distribution and compositional gradient of SiC reinforcement in the Al matrix though the thickness direction was successfully fabricated. The thermal conductivity of Al-SiCp composites was measured at room temperature, 200°C and 400°C using laser flash method. Thermal conductivity of Al-SiCp composites increases non-linearly with decreasing the volume fraction of SiC. Cyclic thermal shock fatigue tests were performed by immersing Al-SiCp functionally graded materials(FGM) into water from the various heating temperatures of 400°C , 300°C and 200°C , repeatedly. After cyclic thermal shock fatigue tests, micro-hardness was measured and formation of cracks was investigated.e fati
Effect of Sb Addition on the Creep Property of AZ31 Alloy
Authors: Tian Su Gui , Sohn Keun Yong , Kim Kyung Hyun
Published: March 2009

The effects of antimony addition on the microstructures and creep behavior of AZ31 have been studied. Constant load creep tests were carried out at 200°C and an initial stress of 50MPa for AZ31 alloys containing antimony up to 0.84% by weight. Results show that Small additions of antimony to AZ31 effectively decreased the creep extension and steady state creep rates. The steady state creep rate of AZ31 was reduced 2.5 times by the addition of 0.84% of antimony by weight. The main reason for the higher creep resistance is due to the presence of high volume fraction (~20%) of second phases including Mg3Sb2, which effectively hindered the movement of dislocations during the elevated temperature creep.
Grain Refinement on AZ31 Magnesium Alloy by Highly Strained and Annealed Method
Authors: Yamamoto Atsushi , Kakishiro M. , Ikeda Masahiko , Tsubakino Harushige
Published: March 2009

Grain refinement in AZ31 magnesium alloy has been attempted by hot-rolling and
annealing process. Specimens were solution heat treated at 673 K for 36 ks, then hot-rolled at 423 - 773 K with total reduction of 20 - 80 % by multi pass process. The rolled specimens were annealed at 473 - 673 K for 3.6 ks. Grain sizes after the solution heat treatment were about 20 to 150 µm. After hot-rolling at 573 K and annealing at 473 K, grain sizes decreased into about 5 to 10 µm. Suppression of grain growth by pinning due to precipitates was observed by transmission electron microscopic observations.
Development of Modified Embedded Atom Method for Alkali Metals
Authors: Yuan Xiao Ying , Takahashi Kunio
Published: March 2009

The modified embedded atom method (MEAM) can describe the physical properties of bulk systems for a wide range of advanced engineering materials. However, the MEAM is found to return negative surface energy for Li(100), Li(110) and Li(111), if the relaxation of atomic positions on the surface is taken into account. In order to solve this problem, a new scheme of MEAM for lithium has been developed, by modifying the expression of embedding function. In this work, the new scheme is also applied to the other alkali metals, and the parameter sets of MEAM have been determined by fitting to not only bulk properties but also some non-bulk properties. The new MEAM potentials for alkali metals have been applied to calculate the elastic stiffness of crystal, the vacancy formation energy, the surface energies for low index crystal faces and the bond length and the binding energy for dimer. The results have been compared with experimental values.
Effect of Annealing on the Microstructures and Mechanical Properties of Mo3Si-Mo5Si3 Eutectic
Authors: Yang Hai Bo , Li Wei , Shan Ai Dang , Wu Jian Sheng
Published: March 2009

The microstructures and mechanical properties of arc-melting processed Mo3Si-Mo5Si3 eutectic have been investigated. The Vickers hardness of Mo3Si-Mo5Si3 eutectic alloy at room temperature is on the order of 1350Hv. The fracture toughness value of the alloy at room temperature is 1.39MPam1/2 measured by Single edge-notched beam specimen technique and 1.61MPam1/2 measured by Indentation technique. The compressive strengths at 1300 oC and 1400 oC under a strain rate of 10-4s-1 are about 550MPa and 300MPa respectively.
Synthetic Processes via Complex Precursors of Rare Earth Manganites with the Perovskite and its Related Structures
Authors: Shimono A. , Sato Hirohisa , Kawada-Wada K. , Ito Yasuo , Kamegashira Naoki
Published: March 2009

A development of synthetic process via rare earth complex precursors was applied to a formation of rare earth manganites which can not be easily formed by conventional (normal) process. Several compounds of rare earth manganites with various structures were successfully synthesized by this method and their crystal structures were identified by powder X-ray diffractometry. Both of the orthorhombic and rhombohedral LaMnO3 phases were prepared. LnMn2 O5 phase was more easily prepared by this method than by another method. The solid solution of (Sr,La)2
MnO4 phase for various compositions were tried to prepare a single phase, especially for a composition region Sr/La ratio < 1. since this phase is normally formed for only region of Sr/La ratio .. 1 by the solid state reaction method.
Characteristics of Electron Density Distributions in Metal Oxides
Authors: Morinaga Masahiko , Yoshino M. , Shimode A. , Okabayashi K. , Nakamatsu H. , Sekine R.
Published: March 2009

The electron density distributions in a series of metal oxides are calculated using the
DV-Xα molecular orbital method. It is found that the logarithm of the electron density, logρ(r), decreases with the distance, r, from the oxygen nucleus, while keeping a constant slope relevant to oxygen atom. The magnitude of the slope is about 15.75 for O-1s electrons, and about 6.61 for O-2s, 2p electrons, being nearly close to the respective values of 16 and 8, expected from the radial distribution functions of hydrogen-like atom containing only one electron. The extent of the region for the O-2s, 2p electrons changes with metal species in the oxides, but the slope remains unchanged. Furthermore, it is shown that the nature of the chemical bonding is well represented in log (ρ minZ-3) vs. 2(Z/n) rminb plots, where ρmin is the minimum electron density, rmin is the distance r at ρmin, Z is the atomic number, and n is the principal quantum number.
An Investigation on the Strength-Porosity Relation in Sintered 17-4 PH STS Produced by Powder Injection Molding
Authors: Sung Hwan Jin , Ha Tae Kwon , Ahn Sang Ho , Chang Young Won
Published: March 2009

In the present study, PIM process has been employed to produce sintered specimens with the various porosities from the initial stage of sintering and to the stage of nearly full density. A series of tensile tests has been conducted on these specimens at room temperature to elucidate the effect of a wide range of porosity. The material used in this study was 17-4 PH stainless steel. Based on the results of tensile tests on PIMed specimens with the various porosity, a new approach to predict the strength and the elongation of sintered materials has been carried out and a new framework combining neck growth model and ideal pore model has been established. By applying this new model to not only the results obtained in this study but also to previously published data, its generality and validity were sufficiently verified.
High Temperature Deformation Behavior of a Ti-45.5Al-2Cr-4Nb-0.4B Intermetallic Compound
Authors: Ha Tae Kwon , Jung Jae Young
Published: March 2009

High temperature deformation behavior of a Ti-Al intermetallic compound has been
investigated in this study. Specimens with a near gamma and a lamella structure were obtained by performing heat treatment at temperatures from 1200 to 1330°C for 24 hr, respectively, and stabilized at 900°C for 4 hr followed by air cooling. A series of load relaxation tests has been conducted on these samples at temperatures ranging from 850 to 950°C to construct flow curves in the strain rate range from 10-6/s to 10-3/s. Strain hardening was observed even at the temperature of 950°C in both the near gamma and the lamella structures. Further aging treatment for 12 hr at the test temperatures has been found to cause negligible softening in both microstructures, providing the strong applicability of this alloy system in the temperature range.
Work Hardening and Flow Softening of γ-TiAl Containing Ni
Authors: Zhang Jian Hui , Xia Kenong , Strom Erik , Zhong Zeng Yong , Li Chang Hai
Published: March 2009

This paper presents the true stress - strain curves and data analyses of a
Ni-containing TiAl and its reference alloy based on the isothermal compression tests at 1000°C and 0.01 - 1.0s-1 strain rates. The results show that the minor Ni addition makes the flow softening coming sooner and therefore significantly lowers the peak stress. Those effects, in addition with a better balance between the work hardening and flow softening during hot deformation, improve the steady state flow behavior of TiAl. The Ni-influence mechanisms are also suggested based on the TEM observation of dislocation configurations and lamellar breakdown during the deformation.
Correlation between Microstructure and J-R Fracture Resistance of AISI Type 347 Weld
Authors: Yoon Ji Hyun , Park Jun , Park Soon Dong , Lee Bong Sang , Yoon Eui Pak
Published: March 2009

The influence of the microstructure on the J-R ductile crack growth resistance of austenitic stainless steel AISI Type 347 welds was examined. The optical and electron microscopy, and chemical examinations and XRD analysis were conducted on a series of J-R test specimens which were tested at 316oC. It was concluded that the J-R property of the Type 347 weld decreased with increasing the contents of the Nb(C, N) precipitates which were dependant on the carbon contents of the filler metals. The higher δ-ferrite content also deteriorated the J-R property of the Type 347 weld.
Influence of Shear Speed on the Shear Force of Eutectic Sn-Pb and Pb-Free BGA Solder Joints
Authors: Kim Jong Woong , Yoon Jeong Won , Jung Seung Boo
Published: March 2009

The experimental investigation and non-linear finite element analysis using elastic-viscoplastic constitutive model were conducted to study the effect of ball shear speed on shear force of BGA solder joints. The Ag3Sn intermetallic compound (IMC) particles were found inside the Sn-3.5Ag solder, while the fine intermixed structure of lead-rich phases and tin-rich phases was investigated inside the eutectic Sn-37Pb solder. The shear force linearly increased with shear speed and reached to the maximum value at the highest shear speed in both experimental and computational results. All of the test specimens were fractured like ductile mode, and the plastic strain energy density distributions were deeply related to the failure mechanism.
Effect of Oxygen Content on Thermoelectric Properties of Sintered Bi-Te Based Compounds
Authors: Cho Dong Choul , Lim Cheol Ho , Lee D.M. , Shin Seung Y. , Lee Chung Hyo
Published: March 2009

The n-type thermoelectric materials of Bi2Te2.7Se0.3 doped with SbI3 were prepared by spark plasma sintering technique. The powders were ball-milled in an argon and air atmosphere. Then, powders were reduced in H2 atmosphere. Effects of oxygen content on the thermoelectric properties of Bi2Te2.7Se0.3 compounds have been investigated. Seebeck coefficient, electrical resistivity and thermal conductivity of the sintered compound were measured at room temperature. It was found that the effect of atmosphere during the powder production was remarkable and thermoelectric properties of sintered compound were remarkably improved by H2 reduction of starting powder. The obtained maximum figure of merit was 2.4 x 10-3/K.
Characteristics of Ni-Ti-Zr-Si-Sn Bulk Amorphous HVOF Coating
Authors: Lee Sang Yong , Choi Han Shin , Lee Chang Hee , Kim Yong Jin
Published: March 2009

This study was conducted to observe the influence of oxygen to fuel ratio[O2/H2 ratio] of HVOF(High Velocity Oxygen Fuel) process on the amorphous formation and coating properties of NiTiZrSiSn bulk amorphous alloy. The bulk amorphous feedstock was prepared by inert gas atomization. Amorphous contents were followed by differential scanning calorimetry(DSC). Microstructural characterization was done by scanning electron microscope(SEM) and x-ray diffraction(XRD). Mechanical properties were obtained by Vickers microhardness testing and pin on disk wear testing. A maximum 72% amorphous phase could be obtained with an optimum O2/H2 ratio. High amorphous content resulted in a low friction coefficient and weight loss than high oxide content coating and fully crystallized coating.
Structural and Optical Features of Si-Rich SiO2 Films Prepared by Magnetron Sputter Techniques
Authors: Kim Sang Wook , Cho Nam Hee , Im Seongil
Published: March 2009

Si-rich SiO2 (SRSO) films were prepared by RF magnetron sputter techniques, and the structural and optical features of nanocrystalline Si (nc-Si) embedded in the SiO2matrix were investigated in terms of post-deposition heat-treatment conditions. The SRSO thin films exhibited PL phenomena in the wavelength range of (450 ~ 500 nm). Post-deposition heattreatment at relatively high temperature like 1000 ~ 1100 °C increased the crystallinity of the films as well as the volume of the Si nanocrystallites (and SiO2), and as a result, PL intensity was enhanced in the visible light region. The nc-Si embedded in SiO2matrix is a few nanometers in size. It is believed that the Si nanocrystallites in the post-deposition annealed films are isolated and well passivated by SiO2.
Critical Manifolds in Polycrystalline Grain Structures
Authors: Holm Elizabeth A. , Meinke J.H. , McGarrity E.S. , Duxbury P.M.
Published: March 2009

With the development of new, fully three-dimensional metallographic techniques, there is considerable interest in characterizing three-dimensional microstructures in ways that go beyond twodimensional stereology. One characteristic of grain structures is the surface of lowest energy across the microstructure, termed the critical manifold (CM). When the grain boundaries are sufficiently weak, the CM lies entirely on grain boundaries, while when the grain boundaries are strong, cleavage occurs. A scaling theory for the cleavage to intergranular transition of CMs is developed. We find that a critical length scale exists, so that on short length scales cleavage is observed, while at long length scales the CM is rough. CMs for realistic polycrystalline grain structures, determined by a network optimization algorithm, are used to verify the analysis.
Triple Junction Controlled Grain Growth
Authors: Novikov Vladimir Yu.
Published: March 2009

Grain growth in 2D polycrystals was simulated under the supposition that triple junctions possess a restricted mobility and so impede the migration of grain boundaries. A parameter 0 L = 0 D m taking into account the effect of triple junctions was varied in the range from 0.003 to 270 (m is the ratio of the triple junction mobility to that of grain boundary and 0 D the initial grain diameter). It was shown that at 0 L <0.4–0.5, i.e. at a small 0 D and small m, the growth kinetics becomes linear. It is supposed that the effect of triple junctions on grain growth can be observed in nanocrystalline materials.
Inhomogeneous Deformation and Microstructural Evolution during the Hot Deformation of Al-4.98%Mg
Authors: Ashton M.J. , Humphreys John F.
Published: March 2009

Plane strain channel die compression (PSC) deformation has been carried out on Al-Mg alloys with Mg contents of 0.1 to 5 % at 350°C, and the deformed microstructures characterised by channelling contrast backscattered electron imaging (BSE), secondary electron imaging (SE) and high resolution electron backscatter diffraction (EBSD). Measurements of orientation spread and misorientation gradient obtained from EBSD maps have been used to quantify the microstructural inhomogeneity developing in the 4.98 % Mg alloy. The results are consistent with inhomogeneous plasticity with more deformation occurring in the grain boundary regions. In-situ FEGSEM hot deformation experiments on the Al-4.98 % Mg alloy have provided evidence of stress driven boundary migration at low strains.
Dynamic Recrystallization of Dense Polycrystalline NaCl: Dependence of Grain Size Distribution on Stress and Temperature
Authors: ter Heege J.H. , de Bresser J.H.P. , Spiers C.J.
Published: March 2009

Only few models explain the development of a steady state grain size during dynamic recrystallization, and their microphysical basis is poorly understood. In this study, we investigate mechanical and microstructural data on dry and wet NaCl, deformed at a range of stresses and temperatures at elevated pressure, with the aim to evaluate the different models. The results show that dry NaCl continuously work hardens and shows evidence for recrystallization dominated by progressive subgrain rotation, while the wet material shows, at similar conditions, oscillating stressstrain behaviour and recrystallization dominated by grain boundary migration. Taking into account the distribution of grain size, deformation of wet NaCl is best described by flow laws based on composite grain size sensitive (GSS) solution-precipitation creep and grain size insensitive (GSI) dislocation creep. The recrystallized grain size data in wet NaCl can be modeled with the hypothesis that recrystallized grain size organises itself in the boundary between the GSS and GSS creep domains.
Development of an Ultrafine Grained Ferrite in a Low C-Mn Steel Intensely Deformed under Hot Torsion
Authors: Azevedo G. , Barbosa Ronaldo , Santos Dagoberto Brandão
Published: March 2009

In the last years, several studies concerning ultra refinement of ferrite grains have been conducted using different experimental techniques (ECAP, ARB, HPT). The aim of all investigations was to provide an optmized relationship between mechanical properties and microstructure of steels. The present work, likewise, deals with strain induced dynamic transformation of ferrite. Samples of low C-Mn steel were intensely deformed in hot torsion aiming at the production of ultrafine grains of ferrite thereby enhancing the mechanical properties when compared to hot rolled products. After soaking during 5min at 900°C, the samples were quenched and then reheated and submitted to hot torsion deformation at temperatures of 700 and 740°C. The torsion schedule consisted of 7 isothermal passes leading to a total strain of ≈1, generating an ultrafine microstructure with grain sizes of the order of 1µm. The shape of stress-strain curves so obtained suggested that ferrite refinement occurred by dynamic recrystallization. The various constituents present in the microstructure as well as ferrite grain size and morphology were examined by optical and scanning electron microscopy. Microhardness tests were performed to evaluate mechanical properties.
Formation of High-Angle Grain Boundaries in Iron upon Cold Deformation by Equal-Channel Angular Pressing
Authors: Dobatkin Sergey V. , Kopylov V.I. , Pippan Reinhard , Vasil'eva O.V.
Published: March 2009

At present, the possibility of the formation of high-angle grain boundaries upon severe cold deformation, in particular, equal-channel angular (ECA) pressing is reliably proved. The structure formation upon multi-cycle ECA pressing substantially depends on the route determining the shear plane in the sample upon repeated passes. The route is defined by the rotation of the sample around its axis upon the multi-cycle ECA pressing. There are four main routes: route A, in which the sample is deformed by many passes without any rotations; route Ba, in which the sample is rotated by ± 90°; route Bc, in which the sample is sequentially rotated in the same direction by 90°and route C, in which the sample is rotated by 180° about its axis before each subsequent pass. By the methods of SEM, TEM and EBSD analysis it was shown that the fraction of high-angle boundaries in a-Fe upon cold ECA pressing with an angle of 90° between the channels and N=4 depends on the deformation route and increases according to the route sequence: Ba-C-Bc.
In-Situ Measurements of Growth of Nuclei within the Bulk of Deformed Aluminium Single Crystals
Authors: Schmidt Søren , Huang X. , Juul Jensen Dorte
Published: March 2009

With the 3DXRD microscope it is now possible to follow in-situ the 3D shape of a recrystallizing grain in the bulk of a deformed microstructure. This opens up the possibility of making direct measurements of boundary migration through a deformed matrix. This paper focuses on recrystalliztion in a deformed Aluminum single crystal with initial orientation (112)<111> (Cu).
Characteristics of the Deformed and Recrystallised Grains Obtained after Hot Plane Strain Compression of a Model Fe-30wt%Ni Alloy
Authors: Bai F. , Cizek P. , Palmiere Eric J. , Rainforth Mark W.
Published: March 2009

The development of physically-based models of microstructural evolution during hot deformation of metallic materials requires knowledge of the grain/subgrain structure and crystallographic texture characteristics over a range of processing conditions. A Fe-30wt%Ni based alloy, retaining a stable austenitic structure at room temperature, was used for modelling the development of austenite microstructure during hot deformation of conventional carbon-manganese steels. A series of plane strain compression tests was carried out at a temperature of 950 °C and strain rates of 10 s-1 and 0.1 s-1 to several strain levels. Evolution of the grain/subgrain structure and crystallographic texture was characterised in detail using quantitative light microscopy and highresolution electron backscatter diffraction. Crystallographic texture characteristics were determined separately for the observed deformed and recrystallised grains. The subgrain geometry and dimensions together with the misorientation vectors across sub-boundaries were quantified in detail across large sample areas and the orientation dependence of these characteristics was determined. Formation mechanisms of the recrystallised grains were established in relation to the deformation microstructure.
Microstructural Control in Thick-Walled Nb-Ti-V Microalloyed Linepipe Steels
Authors: Banks K.M.
Published: March 2009

Various microstructure models for Nb-bearing steels were tested under industrial strip rolling conditions to establish a relationship between grain size and toughness in Ti-Nb-V microalloyed steels. For similar Nb contents, microstructure models for Nb steels were found to adequately describe recrystallisation kinetics in more complex Ti-Nb-V steels. For thick-walled linepipe (11.6mm), a minimum of 0.04%Nb is required to achieve adequate toughness. Retained strain was the dominant processing parameter factor affecting ferrite grain size. The predicted minimum amount of retained strain after the last pass required for sufficient grain refinement
concurred with laboratory simulation results. For the rolling schedules investigated, metadynamic recrystallisation was predicted to occur during roughing, whilst static recrystallisation was predominant during finishing.
Coupling Recrystallization and Texture to the Mechanical Properties of Ferritic Stainless Steel Sheet
Authors: Sinclair Chad W. , Mithieux J.D.
Published: March 2009

Obtaining optimal mechanical properties for highly formable ferritic stainless steel sheet requires careful control over recrystallization and texture. This is, in some cases, hampered by the slow approach to final recrystallization associated with the disappearance of deformed grains with particular orientations. The important mechanical properties for formability (e.g. the yield strength and r-value) are thus strongly dependent on the final few percent recrystallization. In this study, it has been attempted to correlate the microstructure and texture of ferritic stainless steel sheet to its mechanical properties as measured in uniaxial tension. It is shown that careful consideration of the evolution of texture and microstructure with recrystallization may explain the observed trends.
Texture Changes during Uniaxial Compression of Mg-3Al-1Zn
Authors: Backx Petra , Barnett Matthew R. , Kestens Leo
Published: March 2009

The mechanical anisotropy of wrought Mg alloys is very high. For example the yield
stress of extruded Mg-3Al-1Zn tested in tension can be as high as twice that obtained in compression [1]. To solve the problems this creates for product design it is necessary to understand the sensitivity of texture to processing parameters. Uniaxial compression tests at different temperatures were performed on cylindrical samples of an extruded Mg-3Al-1Zn bar. The texture during this deformation changes from a situation where all crystal c-axes are nearly perpendicular to the sample axis to one where the c-axes are all nearly parallel to this axis. Compression was stopped at different strains to examine the rate of this texture change. Textures were examined using EBSD measurements. It was found that different mechanisms operate depending on the temperature of deformation and that a variety of textures can be created. Also it was seen that an annealing treatment performed after compression has an influence on the texture. Afterwards the samples were subjected to another uniaxial compression test to examine the influence of texture on room temperature properties.
Influence of Oxygen Content on the Static Recrystallization of ETP Copper
Authors: Jakani S. , Mathon Marie Helene , Gerber Ph. , Benyoucef Mustafa , De Novion C.-H. , Baudin Thierry
Published: March 2009

Cold-drawn Electrolytic Tough Pitch copper wires have been investigated with
Neutron Diffraction and Electron Back Scattered Diffraction. The drawn copper wires (38% reduction in area) develop major <111> and minor <001> fiber textures. It appears that the texture intensity of the reinforcements within the <111> and <001> fibers is more pronounced in the center and intermediate part of the wires. During the first annealing time, it is found that the recrystallization kinetics is enhanced when oxygen content is increased. The recrystallized fraction within the intermediate zone of the wire is two times larger in the cathode with higher oxygen content. The mechanisms at the origin of this acceleration of recrystallization kinetics
will be discussed taking into account the presence of Cu2O type oxides.
Microstructure and Texture Evolution during Static Recrystallization of Zr-2Hf Alloy
Authors: Zhu K. , Chaubet D. , Bacroix Brigitte , Béchade Jean Luc
Published: March 2009

The recrystallization of a Zr-2Hf alloy sheet deformed by plane strain compression at
room temperature and then heat treated in the temperature range 500-650°C is studied. The microstructure, local and global crystallographic textures are investigated by EBSD and X-ray techniques. The as-deformed condition exhibits a heterogeneous microstructure composed of highly and less deformed zones, the EBSD indexing of the latter ones being more reliable. The asdeformed condition displays a (0001) < 0 1 10 > crystallographic texture. The evolution of the
microstructure during recrystallization very much depends on the amount of local deformation. Recrystallization begins in highly deformed zones, new grains having two variants of texture components, {0001} < 0 1 10 > and {0001} < 0 2 11 >. Some change of preferred orientations concomitant with grain growth at 600 and 650°C has been observed with a decrease in the {0001} < 0 1 10 > component and an increase in the {0001} < 0 2 11 > component.
Texture of High Temperature Superconductor Thick Films Tl-1223 and Tl-2223/LaAlO3 Deposited by Spray Pyrolysis
Authors: Nguyen Xuan H. , Beauquis S. , Galez P. , Jorda J.L. , Phok S. , De-Barros D.
Published: March 2009

Superconducting Tl-1223 and Tl-2223 films have been prepared in a two steps process : deposition of Ba:Ca:Cu = 2:2:3 precursor by spray pyrolysis and ex-situ thallination. Pure textured Tl-1223 films with good superconducting properties (Tc = 113K and Jc = 0.7 MA/cm2 at 77K, 0T) have been obtained. Almost pure Tl-2223 films have been obtained when precursor films have been thallinated with fluorinated sources.
Investigation of Nucleation Mechanisms of Recrystallization in Warm Rolled Fe3Al Base Alloys
Authors: Konrad Joachim , Zaefferer Stefan , Schneider André
Published: March 2009

It has been shown in literature that the mechanical properties of Fe3Al base alloys are strongly dependent on the heat treatment subsequent to warm rolling. Therefore, the recrystallization behavior of 3 different hot and warm rolled and annealed Fe3Al-based alloys has been investigated. Two of these alloys contain different forms and amounts of second phase particles, while a pure binary alloy was taken as reference. All alloys develop a-(<110>||RD) and g-(<111>||ND) fiber bcc-type rolling and annealing textures, however, the amount of a- and g-fibers vary in dependence of the alloy composition. The current work presents the investigations on the nucleation process during annealing that has been studied by means of high resolution backscatter electron diffraction (EBSD) in the SEM. In particular the occurrence of orientation gradients in the deformed structure and their
crystallographic relationship to the formation of new grains was investigated. It was shown, that small particles favor the a-fiber component by hindrance of the growth of new grains. In contrast, large particles lead to particle stimulated nucleation. This weakens the overall texture but does not randomize it since the orientation gradients around particles keep a relationship with the matrix orientation.
A Statistical Mechanics Theory of Grain Deformation and Its Prediction of Dynamical Recovery and Recrystallization
Authors: Rivera-Díaz-del-Castillo Pedro E.J. , van der Zwaag Sybrand
Published: March 2009

A novel statistical mechanics approach to quantify the effects of hot rolling and deformation on the formation of dislocations in a single grain scenario is presented. The dislocations are dealt as equilibrium defects in the crystal structure, which is assumed to be deformed via the formation of dislocations or single atom displacements at the grain boundary, which involve breaking their bonds and are thus termed “bond breaking atoms”. The deformation process is applied to steels of a variety of grain size and dislocations densities. The model has the capacity to describe the grain energy increase as a function of crystallography, grain sizes, temperature and degree of deformation, providing thus an aid in predicting the conditions for dynamic recovery and recrystallization.
Sharpening of Cube Texture during Grain Growth in High Purity Aluminum
Authors: Murakami Takeshi , Ochiai Shouichi
Published: March 2009

Grain growth in cube-textured aluminum was investigated by transmission Laue
photographs obtained at the same point in specimens with progressing annealing at the heating rate of 20 deg/h. High purity aluminum for electrolytic capacitor was cold rolled to 98 % reduction, and subsequently partially annealed at 230 °C for 6 h and rolled 22 % reduction. On the light rolling, asterisms toward RD were observed near by direct beam, suggesting that lattice rotation around TD was caused in cube grains by light rolling. After annealing to 300 deg, fine Laue spots were detected
in the asterisms. Those fine spots were indexed as 100 spots due to diffraction in {100} nearly parallel to the ND-TD plane. After disappearance of Debye arcs due to diffraction in untransformed matrix, cube texture was observed with orientational spread around TD. With continuing annealing to 540 °C , grain growth occurred at the expense of cube grains whose orientations deviated from the exact cube
orientation around TD , resulting in sharp cube texture formation.
Orientation Aspects of the Recrystallization Nucleation in Highly Deformed Polycrystalline Copper
Authors: Sztwiertnia Krzystof
Published: March 2009

The orientation dependence of recrystallization nucleation in 95% cold-rolled polycrystalline copper was studied by means of electron microscopy and calorimetry. Local orientation characteristics of microstructure at the beginning of recrystallization process were analyzed. Combined calorimetric and microscopic investigations, including local orientations measurements, imply that recrystallization is a superposition of several local processes that develop in two steps. In the first step, discussed in this paper, recrystallization process develops in the areas of localized strain, including shear bands and regions of more or less distorted matrix subgrains. Orientations of nuclei reproduce all components of deformation texture. Further growth of nuclei is accompanied by selective generation of successive recrystallization twins. In fact, not single grains are growing, but entire colonies comprising the nuclei developed from fragments of deformed matrix and recrystallization twins [e. g. 1].
Grindability Evaluation of Advanced Ceramics
Authors: Yu Ai Bing , Zhong L.J. , Tian Xin Li
Published: March 2009

Evaluation system of grindability was proposed for advanced ceramics. Grinding forces and material removals of SiC, Al2O3, Si3N4 and ZrO2 were measured. Grindabilities of ceramics were evaluated with property parameters based on fuzzy comprehensive evaluation theory. The experimental results suggest that grindabilities of SiC and Al2O3 are better than those of Si3N4 and ZrO2. The fuzzy evaluation results show grindabilities of SiC and Al2O3 ceramics are classified as
grade of very easy to grind, and Si3N4 and ZrO2 are classified as grade of difficult to grind. The ranking of maximum grinding principal stresses of ceramics considering Poisson’s ratio is SiC, Al2O3, ZrO2 and Si3N4. Theoretical analysis calculated with property parameters is consistent with experimental results in comparison of grinding output parameters. The proposed evaluation system for ceramic grindability is feasible, and the evaluated results are comprehensive and reasonable.
Fast Consolidation of Iron Powders by Pulse Electric Current Sintering
Authors: Li Yuan Yuan , Long Yan , Li Xue Qin , Chen Wei Ping , Xia Wei
Published: March 2009

Iron powders were successfully consolidated by a Pulse Electric Current Sintering
(PECS) process in a short heating duration of 6 min. Microstructure and chemical composition of the sintered samples were studied by an optical microscope, scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). Experimental results showed that both the densification of powders and inter-diffusion between elements were accelerated by increasing of the pulse peak. No noticeable grain growth was observed in the sintered samples. When the peak of
pulse current increased, the density and transverse rupture strength of the sintered samples were improved.
The Application of Numerical Control Based on Network Manufacturing in Plastic Window Production
Authors: Ze X.B. , Ding H. , Wang H. , Wang Xiao Qin
Published: March 2009

In this paper, the character of profile material cutting is analyzed; the dynamic alliance structure of plastic window production and its quick response to the varied and individualized requirements are introduced; the formation of network manufacturing environment and the practice of NC technology in the environment are illustrated; and then the method of improving the material utilization and the ability of flexible manufacturing are put forward.
On CNC Machining and Part Program Preprocessing Based on STEP-NC
Authors: Zhang Cheng Rui , Liu Ri Liang
Published: March 2009

STEP-NC is a new CAM/CNC interface and an extension of STEP into numerical control machining. It has been partly formed into draft international standard (ISO 14649) and is expected to replace ISO 6983 in the near future. In the first section of this paper, the STEP-NC data model is analyzed and those parts that are relevant to NC milling process are abstracted. Then issues involved in NC part machining based on STEP-NC paradigm are discussed including NC programming and the machine control. Based on the analysis, a prototype system is outlined and partly developed with libraries and software tools in ST-Developer environment to interpret the part program into internal data format and to assist the shop floor level planning. Finally the user interface of this system is introduced.
Plasma-Particle Interaction in Spray Forming
Authors: Fang Jian Cheng , Xu Wen Ji , Zhao Zhi Yu
Published: March 2009

The quality of spray-formed parts is the most important research field in plasma spraying, which has been developed in rapid forming the materials of difficult processing such as ceramics, high melting point alloy and composite materials in recent years. It is insufficient to research the forming quality affected by the plasma-particle interaction based on the plasma characteristics. The temperature field distributions of plasma jet have been investigated under the different conditions by
imaging and processing, and the experimental measurements of surface temperature for in-flight particle have been carried out by the principle of two-wavelength pyrometer. At the same time, the mathematical models of momentum and energy transfer have been established to analyze the motion laws and temperature distribution of in-flight particles during spraying. The results show that the temperature field distribution of plasma jet is obviously affected by the components of working gas, the forming quality is significantly influenced by the flight time and melting state till arriving at the spray mould, in which the mechanical behavior and the heating characteristic of plasma-particle interaction in spraying system should be properly matched with each other. The mathematical simulations of temperature are in a good agreement with experimental results.
Electrical Discharge Grinding of Polycrystalline Diamond
Authors: Pei Jing Yu , Guo Chang Ning , Hu De Jin
Published: March 2009

This paper presents the tests of electrical discharge grinding (EDG) of polycrystalline diamond (PCD) on electrical discharge machine tool with high speed rotating device. The effects of wheel speed, open circuit voltage, peak current, pulse on time, and pulse off time of EDG on the material removal rate (MRR), wheel wear rate (WWR) and surface roughness (SR) are investigated respectively. The tests indicate that it is possible to shape PCD blank with EDG. The wheel speed makes the MRR increase dramatically. The higher the open circuit voltage, the larger is the MRR. The effect of peak current on the MRR, WWR and the SR is similar with that of open circuit voltage. However, the influence of the peak current is much larger than that of the open circuit voltage. Moreover, the peak current should be smaller than 32A. There is a best ratio between the pulse on time and pulse off time. If a ratio is larger or smaller than that value, there may be adverse effect on the SR and the MRR. Large pulse on time makes the MRR increase and the WWR decrease. However, all the parameters investigated have little influence on the SR of PCD. The SR is determined mainly by the grain size of PCD.