bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Second Phase Particles on Recrystallisation of Cold-Rolled Low Carbon Microalloyed Steels during Isothermal Annealing
Authors: Capdevila Carlos , De Cock Tommy , García-Mateo Carlos , Caballero Francisca García , García de Andrés Carlos
Published: March 2009

The recrystallisation behaviour of two cold-rolled low carbon microalloyed steels with
different Ti content was investigated by thermoelectric power (TEP) measurements and metallography. It was shown that recrystallisation was more sluggish in the higher Ti grade steel as compare with traditional ELC and LC steels. The existence of Ti in solid solution together with the pinning effect of Nb-, V- and Ti-rich particles are likely to be responsible for such behaviour. Metallographic etching with picral revealed that cementite act as preferential nucleation site for recrystallisation.
The Precipitate-Nucleation in the Vicinity of Solubility Limit
Authors: Miyazaki Toru , Kozakai Takao , Schoen Claudio G.
Published: March 2009

The critical minimum size of stable precipitate in the vicinity of edge of miscibility gap is experimentally determined for the Ni3Si precipitate particle in Ni-Si, Ni3Al in Ni-Al, Cu4Ti in Cu-Ti and Co in Cu-Co binary alloy systems by utilizing the macroscopic composition gradient method recently proposed. The results obtained are as follows: The critical nucleus size shows a rapid increase to several tens of nm in a very narrow composition region less than 0.3at% from the phase boundary. Such a big critical size of nucleus is statistically rationalized by the conventional nucleation theories.
Atomistic Computer Modeling of Intermetallic Alloys
Authors: Mishin Yuri M.
Published: March 2009

The paper gives a brief overview of our recent work on atomistic computer modeling of ordered intermetallic compounds of the Ni-Al and Ti-Al systems. Atomic interactions in these systems are modeled by semi-empirical potentials fit to experimental and first-principles data. The methodology includes a large variety of techniques ranging from harmonic lattice dynamics to molecular dynamics and Monte Carlo simulations. The properties studied include lattice characteristics (elastic constants, phonons, thermal expansion), point-defect properties, atomic diffusion, generalized stacking faults, dislocations, surfaces, grain boundaries, interphase boundaries, and phase diagrams. We especially emphasize the recent progress in the understanding of diffusion mechanisms in NiAl and TiAl, calculation of stacking fault energies in Ni3Al in relation to dislocation behavior, and calculations of / 0 interface boundaries in Ni-Al alloys.
Mechanical Alloying and Powder Consolidation in SiC and Hydoxyapatite
Authors: Kimura Hiroshi , Hanada Kenji , Ishigane Kiyohiko
Published: March 2009

The reaction ball milling can produce the solid state amorphization of covalent ceramic, SiC, including the mechanical alloying (MA) of the elemental crystalline powder mixture of Si and C and the mechanical grinding (MG) of the commercial β-SiC particle and MG of the nanocrystalline β-SiC powder as synthesized via ’high-energy’ MA. An increase in amorphous volume (X) by decreasing crystallite size (d) during MG is expressed by a relation of X= 1-{d/(d+∆)}3 with the intercrystal thickness (∆) of 1 nm. The rotating-arm reaction ball milling is used to synthesize nanocrystalline (nc) hydroxyapatite by MA of the powder mixture at 303 K, according to a reaction of 6CaHPO4･2H2O+4Ca(OH)2→nc-Ca10(PO4)6(OH)2+8H2O with JMA exponent of 1. By employing the pulse electric discharge consolidation, the amorphous SiC powder compact shows a rapid densification during Newtonian viscous flow as expressed by an Arrhenius relation with the activation energy of 495 kJ･mol-1, and then obtain the full densification at 2033 K under 100 MPa. The nanocrystalline hydroxyapatite powder with the crystallite size of 8 nm can be consolidated at full-density at 1023 K under 150 MPa, following a rapid shrinkage during superplastic flow from 900 K. The fracture toughness (KIC), as deduced from the indentation microfracture method, is the high level of 13 MPa･m0.5 for nanocrystalline SiC with 12 nm.
Preparation of Super-Hard Nanocomposite Films by ICP Assisted Magnetron Sputtering
Authors: Miyake Shoji , Li Zhuguo
Published: March 2009

Super-hard nanocomposite films were deposited on Si(100) substrates with irradiation of a high-density (~2.0 mA/cm2) low-energy (~22 eV) ion flux by an inductively coupled plasma (ICP) assistance to magnetron sputtering process. Low-stress, super-hard nanocomposite Ti-Cu-N and Ti-Si-N films could be synthesized at low deposition temperatures below 300 oC. Prepared films exhibited a pronounced TiN(200) texture and the film hardness was significantly enhanced by the addition of Cu and Si, where a maximum value of 42 GPa at approximately 2 at% Cu addition and 48 GPa at approximately 5.8 at.% Si. Ti-Cu-N films were consisting of nanocolumns of TiN crystallites with dispersion of Cu crystallites around the columnar boundaries. While Ti-Si-N films were characterized as having a nanocolumns of TiN crystallites with amorphous Si3N4 inside the columnar boundaries. The residual compressive stresses of these films were lower than 1.5 GPa and no refinement of crystallite size by the addition of Cu and /or Si was observed, from which the hardness enhancement was attributed to a nanocomposite effect.
Reflecting Multi-Layer Coatings by RF Sputtering
Authors: Tamai Fujio , Kawakami Yuji
Published: March 2009

This work is concerned with the proposition of high contrast multi-layer structure for the fabrication of reflecting surface in the visible range. The multi-layer SiO2/Ta2O5 system has superior heat resistance and reflecting properties. Ta2O5 and SiO2 thin films were prepared by RF plasma sputtering in Ar-O2 mixed gas using Ta2O5 and SiO2 target respectively. Secondary ion mass spectroscopy and SEM observation were performed in order to investigate the multi-layer structure. The XRD and XPS analyses were also performed in order to investigate the crystal structure and the chemical state of the films. The optical constants of Ta2O5 single film were investigated by the ellipsometric analysis. Using the Ta2O5 film doped Bi2O3 for a reflecting multi-layer structure improved the reflecting properties and the heat resistance of the multi-layer system because of the high refractive index of the doped film.
Development of Technology for Reduction Process of Copper Production
Authors: Živković Živan , Živković Dragana , Jovanovic Aca , Mihajlovic Ivan
Published: March 2009

In this paper results regarding development of reduction process for copper production are presented. This process is applicable for small smelting plants of capacity up to 30.000 t/year, with capability for treating poly-metallic Cu-Zn-Pb concentrates with dangerous level of toxic components presence (As, Cd, Hg, …). This procedure is interesting because it can be applied for smelters that are supplied from mines at the end of exploitation so in the edge sectors poly-metallic minerals appear. Procedure consists of oxidation roasting of copper concentrate with desulphurisation degree over 98% and reduction smelting of sintered roasting products in shaft furnace of special construction. Using process of slag fuming, the degree of Cu and (Au+Ag) utilization can rise over 98% which results in good economic parameters, environment protection and low investment comparing to technologies currently used, taking in mind that phase of concentration is excluded from this technology.
Interfacial Reaction between Sn-Ag Based Solders and Au/Ni Alloy Platings
Authors: Uenishi Keisuke , Kobayashi Kojiro F.
Published: March 2009

The microstructure and strength for the micro joints of Pb free Sn-Ag based solders with Au/Ni alloy platings were investigated. For the joint using Sn-Ag solder, Ni3Sn4 reaction layer formed at the solder/pad interface and also P-rich layer formed in Ni-P plating. The P-rich layer was confirmed to be composed of Ni-P-Sn ternary compound layer and crystallized Ni3P layer. Both of them introduced defects, which degraded the joint strength. Addition of Cu to Sn-Ag solders suppressed the formation of such a P rich layer while the (Cu, Ni)6Sn5 reaction layer was formed at the solder/pad interface. These different interfacial reactions would affect the changes in the joint strength during heat exposure at 423K. On the contrary, addition of Co to Ni platings enhanced the interfacial reaction and the Sn-Ag solder completely transformed to the intermetallic compounds under higher melting temperature even by heating to 543K. The addition of Co in Ni could change the interfacial reaction layer from Ni3Sn4 to (Ni, Co)Sn2 with higher diffusivity of Ni which enhanced formation of intermetallic phases. The control of interfacial reaction by the alloying elements is important to obtain ideal micro joints.
Joining of Tungsten-Copper Using Pulse Electric Current Sintering Method
Authors: Fukuzawa Yasushi , Nagasawa Shigeru , Watanabe Masahiro , Takaoka Shigehiko
Published: March 2009

To develop the new bonding method under low bonding temperature and short holding duration, pulse electric current sintering (PECS) method is applied. The Ni plating layer was used as the interlayer. The following experimental factors were researched:(1) Thickness of Ni plating layer, (2) Bonding temperature, (3) Bonding pressure and (4) Heat treatment after plating. The bonding strength of W-Ni plate-Cu joint could be obtained under low bonding temperature of 773 K and short bonding duration of 10 min.
Comparative Study on Microstructure and Strength of TiAl/Steel Joints Brazed with Ag-Cu-Ti and Ag-Cu-Zn Filler Metals
Authors: Liu Hui Jie , Feng Jicai
Published: March 2009

Vacuum brazing of a TiAl-based alloy to a medium-carbon steel has been carried out at 1173 K for 2-40 min using Ag-Cu-Ti and Ag-Cu-Zn filler metals. The formation phases and interface structure or microstructure of the joints were investigated by SEM, EPMA and XRD, and the strength of the joints was determined by the shear testing method. The experimental results indicate that (1) Ti(Cu,Al)2, Ag(s.s.), Ag-Cu eutectic and TiC phases have occurred in the TiAl/steel joints, and their amount changes with the brazing time; (2) the interface structures of the joints brazed with the Ag-Cu-Ti filler metal is TiAl/Ti(Cu,Al)2+ Ag(s.s.)/Ag(s.s.)+Ti(Cu,Al)2/TiC/steel, while the microstructure of the joints brazed with the Ag-Cu-Zn filler metal is composed of a continuous TiC layer and a mixed zone of Ti(Cu,Al)2, Ag(s.s.) and Ag-Cu eutectic; (3) the shear strength of the joints brazed with the Ag-Cu-Ti filler metal monotonously decreases with increasing brazing time, while the shear strength of the joints brazed with the Ag-Cu-Zn filler metal first rises and then decreases, accordingly an optimum brazing time exists; (4) the maximum shear strengths of the TiAl/steel joints brazed with the Ag-Cu-Ti and Ag-Cu-Zn filler metals are 170 and 190 MPa, respectively.
Crystal Restoration during Severe Plastic Deformation
Authors: Stüwe H.P.
Published: March 2009

Severe plastic deformation of metals leads to changes in microstructure, which in turn are responsible for unusual bulk properties. There are two (interrelated) processes leading to change of microstructure:
1) the production of a very high number of dislocations, leading to a high dislocation density,
2) the “fragmentation” of the original crystal grains into much smaller structural elements leading to what is sometimes called “nanocrystalline” material.
Under continued strain neither of these two processes will continue indefinitely. Instead, the microstructure will reach a steady state. Under certain conditions its development may even be reserved.
This indicates the operation of restoration mechanisms such as dynamic recovery and recrystallisation. The actual state of art will be discussed on the basis of current experiments.
Channel Configuration Effects in 3D-ECAP
Authors: Rosochowski Andrzej , Olejnik Lech , Richert Maria W.
Published: March 2009

This paper explains the concept of 3D-ECAP with “in-die rotation” and presents the results of experiments for two sets of tooling with channel passages orientated at 90° and 120°. The results for aluminium 1070 are compared in terms of the process force, billet end effects, mechanical properties and structure of the material.
Synthesis of Bulk Materials by Equal Channel Angular Consolidation of Particles
Authors: Wu Xiao Lin , Xia Kenong
Published: March 2009

Pure aluminium and titanium powders were successfully synthesised into bulk materials using equal channel angular (ECA) consolidation. Powders were used directly without the need to cold-compact them into green bodies. The processing temperatures were significantly lower than the usual sintering temperatures for aluminium and titanium. Fully dense bulk samples were achieved after one pass of ECA deformation through a 90 degree die. Mechanical properties of the as-ECA processed materials were comparable to those of wrought aluminium and titanium through ingot metallurgy. Multiple passes of ECA deformation resulted in refined microstructure and improved mechanical properties. The new process has many advantages over conventional powder sintering and is capable of producing bulk nanomaterials of high integrity.
Magnetic Properties and Microstructure of a FeCo Ferritic Steel after Severe Plastic Deformation
Authors: Vorhauer A. , Rumpf K. , Granitzer P. , Kleber Siegfried , Krenn H. , Pippan Reinhard
Published: March 2009

A commercial FeCo ferritic steel with an initial grain size of 10 μm was subjected to Severe Plastic Deformation in a temperature range between 293 K (0.16Tm, Tm: melting temperature in K) and 723 K (0.4Tm) up to strain levels where a saturation of the microstructural refinement is observed. The microstructure of the severely deformed state is analyzed by Back Scattered Electrons micrographs captured in a SEM. The magnetic properties were characterized by means of SQUID-magnetometer providing information about the magnetization behavior of the material in the as processed state. Depending on the deformation temperature mean microstructural sizes in the steady state of 50 nm and 270 nm were observed after SPD at 293 K and 723 K, respectively. These small microstructural sizes influences significantly the magnetic properties of the material: it shifts the behavior from soft-magnetic in the initial coarse grained state towards a hard-magnetic with decreasing size of the crystallites. For sizes of the crystallites smaller than about 100 nm the magnetic properties become again more soft-magnetic.
On Structural Mechanism of Continuous Recrystallization in Ferritic Stainless Steel after Large Strain Processing
Authors: Belyakov Andrey , Kimura Yuuji , Tsuzaki Kaneaki
Published: March 2009

The annealing behaviour of an Fe – 22%Cr – 3%Ni ferritic stainless steel processed by bar rolling/swaging to total strain of 4.4 at an ambient temperature was studied in the temperature range of 400 ~ 700oC. The annealing behaviour was characterised by the development of continuous recrystallization involving recovery processes followed by a normal grain growth. The large strain deformation caused the very fast recovery resulting in the development of almost equiaxed polygonized microstructure in place of the highly elongated deformation (sub)grains. The polygonization development was accompanied by some increase in the transverse (sub)grain size and the formation of many low-angle subboundaries. The latter ones could be composed from the dislocations, which were emitted by the strain-induced deformation (sub)boundaries. In spite of relatively large fraction of low-angle subboundaries, such polygonized microstructure was essentially stable against a discontinuous grain coarsening. Upon further annealing, therefore, the microstructure evolution was considered as a normal grain growth.
Application of Twist Extrusion
Authors: Varyukhin Viktor , Beygelzimer Yan , Synkov Sergey , Orlov Dmitry
Published: March 2009

Twist Extrusion (TE) is a process of severe plastic deformation (SPD) being developed by us during recent 5 years. Upon this time we published few papers on mechanics of the process and influence of the TE processing on materials structure and properties. Here we reported some results on application of the twist extrusion processing and made few general conclusions.
Ultrafine Grained Dual Phase Steels Fabricated by Equal Channel Angular Pressing
Authors: Shin Dong Hyuk , Kim Woo Gyeom , Ahn Jung Yong , Park Kyung Tae , Kim Yong Suk
Published: March 2009

Ultrafine grained (UFG) ferrite-martensite dual phase steels were fabricated by equal channel angular pressing and subsequent intercritical annealing. Their room temperature tensile properties were examined and compared to those of coarse grained counterpart. The formation of UFG martensite islands of ~ 1 μm was not confined to the former pearlite colonies but they were uniformly distributed throughout UFG matrix. The strength of UFG dual phase steels was much higher than that of coarse grained counterpart but uniform and total elongation were not degraded. More importantly, unlike most UFG metals showing negligible strain hardening, the present UFG dual phase steels exhibited extensive rapid strain hardening.
Effect of Equal-Channel Angular Pressing on the Pitting Corrosion Resistance of Al Alloy
Authors: Son In-Joon , Nakano Hiroaki , Oue Satoshi , Kobayashi Shigeo , Fukushima Hisaaki , Horita Z.
Published: March 2009

The effect of equal-channel angular pressing (ECAP) on the pitting corrosion resistance of Al and Al-Mg alloy was investigated by means of polarization curves in solutions containing 300 ppm of Cl- and by surface analysis. The potentials for pitting corrosion of Al and Al-Mg alloy were evidently shifted to the noble direction by using the ECAP process, indicating that this process improves resistance to pitting corrosion. This increase in resistance seems to be attributable to the increase in formation rate of Al oxide films due to the increase in grain boundary with ECAP. The pitting corrosion resistance of Al and Al-Mg alloy anodized galvanostatically in H2SO4 solution after ECAP was also investigated using electrochemical techniques. The pitting corrosion resistance of Al and Al-Mg alloy was remarkably improved by anodizing. However, the pitting corrosion resistance of anodized Al-Mg alloy was better without ECAP than with ECAP.
Equal Channel Angular Pressing of Magnesium Alloy Containing Quasicrystal Phase
Authors: Zheng Ming Yi , Xu Shi Wei , Qiao Xiao Guang , Gan Wei Min , Wu Kun , Kamado Shigeharu , Kojima Yo , Brokmeier Heinz Günter
Published: March 2009

ZWK510 (Mg-5.0wt%Zn-0.9wt%Y-0.2wt%Zr) magnesium alloy containing Mg3YZn6 quasicrystal phase was prepared by conventional permanent mold casting. Part of the cast ingot was subjected to equal channel angular pressing (ECAP) directly; another part of the cast ingot was extruded initially, then ECAP was applied to the extruded alloy. After 4-pass ECAP, the fraction of coarse grains of the as-cast alloy was decreased to about 30%, and the grain size of fine grain was decreased to about 2 μm. Both strength and ductility of the as-cast ZWK510 alloy were significantly improved with increasing ECAP passes, which was resulted from broken and dispersed I-phase, and fine grains formed due to recrystallization. The as-extruded ZWK510 had an initial grain size of about 2 μm and bands of quasicrystal phase parallel to the extrusion direction. After the extruded alloy was subjected to ECAP, the grain size of the extruded alloy was further refined, the grain size was refined to below 0.5 um after 8-pass ECAP; and the quasicrystal phase was further broken and dispersed in the matrix. After ECAP, the elongation to failure of the extruded alloy was improved. However, both yield strength and ultimate tensile strength were decreased, which is considered to be resulted from the texture modification during ECAP.
Fabrication of Nano Grain Tungsten Compact by Mechanical Milling Process and Its High Temperature Properties
Authors: Oda Eiji , Ameyama Kei , Yamaguchi Satoru
Published: March 2009

Mechanical milling (MM), which is one of SPD process, is applied to W powder and W-Remixed powder. MM processed W and W-Re powders easily form nano grain structure even though they have high melting temperature. The nano grain formation mechanism in these powders is as follows: multi axial deformation of the powders by milling, at the temperature of 333K at most, produces pan-cake grain structure at first. Extremely dense dislocations result in grain sub-division, and finally nano grain structure with high angle boundary forms. Nano grains with approximately 10 nm in diameter are obtained. The MM powders are sintered using Spark Plasma Sintering process. Sintering and high temperature deformation behaviors of the MM powders are also investigated. The MM treatment enables W powder to be able to sinter at 1273 K while the powder without MM could never sintered at the same temperature. Re addition prevents grain growth during sintering and thus increases hardness of the compacts. A large deformation of W-10mass%Re sintered compact, whose grain size is approximately 450nm, is observed at elevated temperatures.
Heterogeneity and Anisotropy in Microstructure and Mechanical Properties of Pure Copper Processed by Equal Channel Angular Pressing
Authors: Wang Jing Tao , Du Zhong Ze , Kang Feng , Chen Guang
Published: March 2009

Pure copper (99.98%wt) square bars (32x32 mm) were processed by equal channel angular pressing (ECAP) Microstructure evolution was characterized by microscopy. Room temperature mechanical properties were obtained by tensile and micro-hardness tests. With increasing number of ECAP passes and cold rolling reductions, the initial coarse grained structure in the as-received material was transformed gradually into an ultrafine grained microstructure with an average grain size of 0.2~0.3 μm. Subsequent rolling resulted deformation twining in this ultrafine grained microstructure, which gives further strengthening in addition to the strengthening obtained by ECAP. Property anisotropy in three orthogonal directions of samples processed by ECAP was characterized by tensile testing.
Modelling of the Evolution of Dislocation Cell Misorientation under Severe Plastic Deformation
Authors: Estrin Yuri , Tóth László S. , Bréchet Yves , Kim Hyoung Seop
Published: March 2009

A model describing the evolution of the misorientation angle between dislocation cells with plastic strain is proposed. The model is applied to the case of equal channel angular pressing (ECAP) of copper. In a basic version of the model, the evolution of the average misorientation angle is traced. A way of handling the evolution of the misorientation angle distribution function using a probabilistic description is also outlined.
Controlling Mechanism of Ferrite Grain Size Generated through Large Strain Deformation of 0.15C Steel
Authors: Murty S.V.S. Narayana , Torizuka Shiro , Nagai Kotobu
Published: March 2009

During large strain deformation of materials, the width of the initial high angle grain boundaries approaches the order of mean diffusion distances encountered during elevated temperature deformation. Since the evolution of ultrafine grains is attributed to thermally activated processes, the role of interfaces in determining the grain size is significant. In order to investigate into this role, microstructure development in low carbon steel (0.15% C) subjected to large strain deformation was studied with specific reference to the controlling mechanism of ferrite grain size evolution. Plane strain compression tests have been conducted in the temperature range of 773-923K at strain rates of 0.01 s -1 and 1 s-1 and the specimens were deformed to 25% of the original thickness and the Microstructural evolution is studied. Based on the results obtained, diffusion along grain boundaries was found to be the mechanism controlling ferrite grain size in this material processed through large strain deformation.
Microstructure and Mechanical Properties Resulting from Cold Rolling of Equal Channel Angular Extruded Commercial Purity Copper
Authors: Krishnaiah A. , Uday Chakkingal , Venugopal P.
Published: March 2009

Equal channel angular extrusion (ECAE) is a processing method for introducing an ultrafine grain size into a material. In the present study, a two-step severe plastic deformation process was used to produce ultrafine grained copper with significantly enhanced strength. Equal channel angular extrusion was first used to refine the grain size of copper samples. The copper samples were further processed by cold rolling (CR) to a strain of 0.67 (about 50% reduction). This two-step process produced ultrafine grained copper with strengths higher than those of pure copper processed through ECAE only. This paper reports the microstructures and mechanical properties of the copper specimens processed by a combination of room temperature ECAE and CR. The effectiveness of initial processing by ECAE prior to cold rolling is discussed.
An Investigation of Cavitation in the Tensile Testing of a Spray-Cast Aluminum Alloy Processed by ECAP
Authors: Kawasaki Megumi , Xu Cheng , Langdon Terence G.
Published: March 2009

A commercial aluminum 7034 alloy, produced by spray casting and having an initial grain size of ~2.1 μm, was subjected to equal-channel angular pressing (ECAP) through six passes at 473 K. In the as-pressed condition, the microstructure was reasonably homogeneous and the grain size was reduced to an ultrafine grain size of ~0.3 μm. This alloy contains MgZn2 and Al3Zr precipitates which restrict grain growth. In tensile testing at 673 K after processing by ECAP, an elongation of >1000% was achieved at a strain rate of 1.0 × 10-2 s-1 corresponding to high strain rate superplasticity. Quantitative cavity measurements were conducted on the specimens after tensile testing for both the as-received condition and after ECAP. These measurements reveal a significant number of small cavities in the samples and especially in the sample that exhibited a very high elongation. This paper describes the morphology of cavity development in the spray-cast aluminum alloy in both the as-received and as-pressed condition.
Mechanical Properties of Fine-Grained AA1050 after ECAP
Authors: Poortmans Stijn , Verlinden Bert
Published: March 2009

The mechanical properties of fine-grained Aluminium AA1050 produced by ECAP at room temperature, have been investigated under various deformation modes. Because ECAP leads to an unstable microstructure, some samples were annealed at 300°C for 10 minutes in order to stabilise the microstructure. For mechanical testing, cylindrical samples were used in three types of monotonic deformation tests: axisymmetric compression, uniaxial tension and simple shear by torsion. The influence of the deformation mode on the yield locus and strain hardening behaviour has been studied and will be discussed for both hot rolled AA1050, ECAP samples without annealing and annealed ECAP samples. To achieve a better understanding of the strain hardening, some preliminary tests with a change in strain path were also performed. The results of tension tests followed by compression will be reported.
Effects of Severe Plastic Deformation: Mechanical Properties and Beyond
Authors: Estrin Yuri
Published: March 2009

In this talk, a range of effects produced by severe plastic deformation will be considered. In addition to the mechanical property improvements, such as enhanced strength and more favourable conditions for superplasticity, SPD will be shown to produce a much broader spectrum of beneficial effects. Case studies demonstrating accelerated kinetics of nitriding of steels and hydrogenation of Mg alloys will be presented. Further possible applications of SPD techniques will be discussed.
Microstructures and Mechanical Properties of Mg Alloy after Severe Torsion Straining Process
Authors: Miyahara Yuichi , Emi N. , Neishi Koji , Nakamura Katsuaki , Kaneko Kenji , Nakagaki Michihiko , Horita Z.
Published: March 2009

Grain refinement is attempted using severe plastic deformation (SPD) through the severe torsion straining process (STSP) which we have developed recently. The STSP is a continuous process for grain refinement without requirement of any die. In this study, an AZ61 Mg alloy was subjected to STSP at a temperature of 573 K with a rotation speed of 10 rpm and a moving speed of 200 mm/min. With this process, an initial grain size of ~20 μm was reduced to ~2~3 μm. Room temperature compression tests revealed that there were no cracks after 15% of compression for the STSP sample whereas fracture occurred for a conventionally extruded sample. For compression tests at 473 K, no cracks occurred in the STSP samples after 80% compression but compression was feasible without cracking only up to 20% for an extruded sample. It is shown that the STSP can be useful for grain refinement and ductility improvement of the AZ61 Mg alloy.
Substructure of Ultrafine Grained Metals after Intensive External Influences at Study of Field Ion Microscopy Method
Authors: Varyukhin Viktor , Efros B. , Ivchenko V. , Efros N. , Popova E.
Published: March 2009

It has been revealed that in Iridium influenced be severe plastic deformation (SPD) a ultrafine grained (UFG) structure is formed (the grain size of 20-30 nm), but in the bodies of grains there are practically no defects of structure, however, after irradiation a subgrain structure, (subgrain size of 3-5 nm) is formed, and in the bodies of subgrains there are defects. The subgrain structure was also revealed in UFG Nickel and Copper after SPD (subgrain size of 3-15 nm), but in the latter case the observed boundary region is broader and subgrain are highly disoriented.
Using the Hot Embossing Technology to Fabricate the Movable Component on Polymer Material
Authors: Chien Chao Heng , Yu Hui Min
Published: March 2009

It presented a novel manufacturing method that was derived from traditional hot embossing technology to fabricate actuators on polymer material in this paper. The conventional photolithography technology, electroplating, and hot embossing technology were utilized in this process. The plastic deformation properties of thermoplastic polymers were main concept. The metal layer deposited on the silicon wafer could be embedded into the polymer substrate by hot embossing
technology as temperature being above Tg. When the polymer substrate temperature was cooled below the Tg, the polymer is to de-embossing and remove silicon wafer. The metal layer was transferred from silicon wafer to be embedded in the polymer substrate. Owing to the adhesion between the metal layer and polymer material was more than the metal layer and silicon wafer. For instance, the PMMA was employed as the polymer substrate to fabricate the cantilever beam actuator
using the novel technology. Finally, the beam was driven by electrostatic force through 25volts of DC power.
A New Class of Structured Light Patterns for 3-D Imaging Systems
Authors: Hsieh Yi Chih
Published: March 2009

A structured light pattern can be used to acquire the range data of an object from a single camera for 3-D imaging systems and it can be used for practical applications in a dynamic environment, i.e., a scene with moving objects. This paper illustrates the generation of a class of distinct structured light patterns with various sizes (range image points).
Effect of Sacrificial Layer Sizes and Fabrication Process on Deformation Caused by Residual Stress of Center-Anchored Circular Plate
Authors: Lin Meng Ju , Chen Rong Shun
Published: March 2009

During depositing a thin film as a structure layer, residual stress from thermal treatment of depositing process will cause deformation after release. Thus the yield ratio and deformation of the devices may be lowered. This work investigates the effect of sacrificial layer on deformation by residual stress causing when depositing a thin film as structure layer. A model is established by using theory of plates-and-shells to investigate the deformation caused by residual stress when the structure
layers of the devices are center-anchored circular plate. Theoretically, it is found that the deformation would happen when depositing structure layer under higher temperature. And from the analysis, the thicker structure plate will cause less deformation. When the thickness of the structure layer is larger
than 3μm , the maximum deformation will reduce to the order of μm. Furthermore, four cases of different sacrificial layer types and temperature distribution with effect on deformation are discussed. If the thickness of the structure layer is above 5μm, the deformation caused by residual stress is not so important. And it is found that if the thickness of structure layer is 10μm order or above, the residual
stress effect on deformation can be neglected. It is found the sacrificial layer will affect the deformation. But it is found that with the same structure layer thickness, as the sacrificial layer thickness increasing, the four cases have different effect on deformation. The in-plane dimension effect is also considered. When the in-plane dimension of sacrificial layer is above 20 times of outer radius, the in-plane dimension effect is neglected and can considered as an infinite dimension.
A Molecular Dynamics Investigation into the Cooling Characteristics of Ni and Cu Alloys at High Pressure
Authors: Su Ming Horng , Chen Hung Chang
Published: March 2009

This paper studies the phase transitions of Cu and Ni alloys as they cool from melting
temperature to room temperature under high-pressure conditions. The interatomic forces acting between the atoms are modeled by the tight-binding potential. Control over the environmental pressure and the cooling temperature is maintained by a canonical ensemble (N, P, T) system. The numerical results confirm that the metal phase transition is influenced significantly by the pressure conditions, even in the case of pure Cu and Ni metals. Three specific transition pathways are
identified for the Cu and Ni alloys as they cool from melting temperature to room temperature, namely a transition at the melting temperature to a crystalline structure, a transition at the glass transition temperature to a glass (amorphous) structure, and finally solidification at the melting temperature followed by a subsequent transition at the glass transition temperature. The results reveal
that glass transition generally occurs at lower pressures in alloys with higher Cu compositions, while glass transition following prior solidification tends to takes place at higher pressures in alloys with higher Ni compositions.
Approximating the Minimum-Bounding Box of a 3D Model with Minimum Spans for Flush Edges
Authors: Lin Tzung Han
Published: March 2009

In this paper, a method for determining the approximated minimum-bounding box is
presented. This method can only be used in the model that has finite vertices. A concept of the minimum span is introduced to determine one length of the bounding box according to a flush edge. After calculating a minimum span, the minimum-area rectangle of the projection is required to be one candidate of minimum-bounding boxes. In many applications, the volume of the bounding box is requested as small as possible. This paper provides an additional property to keep both one length
and one rectangle of the bounding box are as small as possible.
Vehicle Clustering Phenomenon in Automatic Materials Handling Systems in 300mm Semiconductor Manufacturing
Authors: Liao Da Yin
Published: March 2009

During design and implementation of the automatic materials handling system (AMHS) for a local 300mm semiconductor wafer fab (semiconductor fabrication plant), we observed and found an interesting phenomenon Vehicle Clustering Phenomenon (VCP) from the dynamics of automated vehicles: As time evolves, the distance between any two adjacent vehicles usually becomes very close
enough as if all the vehicles are a long train of vehicles running around the loop. The overall performance thus deteriorates due to this phenomenon. This paper explores the causes of the VCP problem and clarifies its impacts to automatic materials handling operations in 300mm semiconductor manufacturing.
Prognostics for Ball Bearing Based on Neural Networks and Morlet Wavelet
Authors: Huang Run Qing , Xi Li Feng , Liu C.Richard , Lee Jay
Published: March 2009

This paper deals with a new scheme for prognostics of ball bearing based on
Self-Organizing Map (SOM), back propagation neural-network and complex Morlet Wavelet methods. It uses complex Morlet wavelet-based envelope to extract successfully the characteristic frequencies of ball bearing. Then the minimum quantization error (MQE) indicator deriving from SOM is used for performance degradation assessment. Based on Weight Application to Failure Times
(WAFT) technology, which deriving from back propagation neural networks, a prognostics model of ball bearing is developed successfully. And the experimental results show that the proposed methods are greatly superior to the currently used L10 bearing life prediction.
Study on Thin Diamond Wire Slicing with Taguchi Method
Authors: Tso Pei Lum , Yan Bo Huei , Lo Chan Hsing
Published: March 2009

Presently, the loose abrasive wire saw is the most commonly used technique for slicing hard and brittle materials. However its productivity is relatively low. A diamond wire saw has been developed for slicing brittle materials such as silicon wafer. The objects of this paper is to make the thin diamond wire saw apply to high cost production in semiconductor industries with the effective processing parameters such as machined surface roughness, material removal rate, the wear of the
wire and the kerf width of the slicing. Effects of processing parameters on the performance of the diamond wire sawing processes are investigated by using the Taguchi method for this design of experiment (DOE). The analysis of the result shows that the optimal combinations for good surface roughness are small grain size, high wire speed, and low feed rate. Wire speed and feed rate are
positively related to material removal rate.
Model Support Algorithm in Powder Based Three Dimensional Printer
Authors: Lai Wei Hsiang , Cheng Chun I , Huang Mon U. , Chang Hsiu Ming
Published: March 2009

Generally, rapid prototype system, it bases on the operation principle to process layer by layer, and has several kinds of hardware already. The input of STL file format has become the de facto standard in rapid prototyping. With the application of complex material, the variety of product-type using RP technology will be dramatically extended and, no more, be limited in model production. However under the structure of 3D printing, large item production will be possible only
if specific support were applied. This study proposes the hardware and software integrated method with the subject of the three-dimensional printing. The hardware utilizes ink-jet of general two-dimensional printer and combines with the traversing mechanism and the process controls and model material, and piles up in accordance with default layer thickness. As the supporting structure in STL-file format is generated through the concepts of the 3D-printing support generating method
which is carried out by performing projection and displacement of selected triangular surfaces and then the generated 3D model is further constructed by Open GL and saved in STL-file format. As STL file is read, and then builds adjacency to store into the topology data structure. After the operation of direct slicing rule, hundreds of contours in each layer are obtained by using Visual C ++ programming language and OpenGL library to implement the algorithm above. It can confirm exactness that the software output and systematic feasibility of integrating the hardware through the
result of system integration test on the 3D printer.
Geometry Influence of Reflectors for Infrared Rapid Heating on Micro-Injection Molding
Authors: Chang Pei Chi , Hwang Sheng Jye
Published: March 2009

In this paper, the geometry influence of reflectors for infrared rapid surface heating on micro-injection molding was studied. A three-dimension ray tracing combined with transient thermal simulation was used to evaluate the thermal condition of injection mold surface. Several kinds of reflectors were applied to study the heating ability of the infrared rapid surface heating system. A commercially available optical analysis program, TracePro, was used to simulate the infrared emission to the center of mold surface. Thermal module of a structure analysis software, ANSYS, was
used to study the absorption and heat transfer of the infrared heating on the mold surface. Then, Taguchi method was adopted to find the close to optimal reflector for rapid surface heating of micro-injection molding.
An Upper Bound Solution for Upsetting of Two-Layer Cylinder
Authors: Tzou Gow Yi , Alexandrov Sergei
Published: March 2009

An upper bound solution for axisymmetric upsetting of two-layer cylinder made of rigid perfectly plastic materials is provided. An important feature of the solution is that the kinematically admissible velocity field, in addition to the necessary requirements of the upper bound theorem, satisfies the frictional boundary condition in stresses, the maximum friction law. The latter is archived by introducing a singular velocity field such that the equivalent strain rate approaches infinity at the friction surface. The dependence of the upper bound limit load on geometric parameters and the ratio of the yield stresses of the two materials is analyzed. The solution can be used in
industrial applications for evaluating the load required to deform two-layer cylinders.
Dynamic Model Based on Genetic Algorithms of Prediction for the Thermal Deformation of Machine Tools
Authors: Chang Chia Wei , Chu M. H. , Chen Yi Wei , Chien S.Y. , Kang Yuan
Published: March 2009

The compensation of thermal deformation is the most significant for the accuracy of a
machine tool. This study proposes an approach based on genetic algorithms (GA) to build the dynamic model of the prediction for thermal deformation of a machine tool. GA is used to optimize the prediction accuracy by using appropriate number and locations of temperature sensors, the model order and the time delay between temperatures and thermal deformation. The compared results show
that the proposed approach can improve the accuracy of prediction results and better than other methods.
A Study of Liquid Cooling Heat Sink Fabrication and Development in Notebook
Authors: Wang A Cheng , Liang Kuo Zoo , Liu C.C. , Yang C.K.
Published: March 2009

Liquid cooling heat sink has excellent heat dissipation ability at the personal computer. It can also produce the similar effect at the notebook when the same heat sink is used. However, under the installing space is limited in notebook, the size and weight of heat sink must be limited too. Therefore a novel liquid cooling heat sink was fabricated herein to understand the heat dissipation efficiency in the notebook. Wire electrical discharge machining (WEDM) uses heat erosion effect to
remove material and only produces little cutting force on the working surface. Therefore, WEDM has excellent ability to fabricate the straight micro fins (high 1000 μm, width 250 μm, fin gap 400 μm). The WEDM parameters were used to find the precision micro fins in this experiment. The precision micro fins were made when the cutting path offset was 185 μm in WEDM. WEDM would produce
over cutting during long pulse duration and it caused oblique micro fins. The appropriate off time in cutting process would promote the WEDM efficiency. However, a liquid cooling heat sink with uniform micro fins and slits was obtained using WEDM.
Predictive Modeling of Scuffing Performance of Gear Oil with MoDTC Using Response Surface Methodology
Authors: Jeng Yeau Ren , Hwang Shen Jenn
Published: March 2009

This paper presents an experimental investigation of the influence of scuffing conditions on two-roller test rig. The prediction of Scuffing load capability model for the gear oils containing molybdenum dithiocarbomate (MoDTC) was developed based on the response surface methodology. A good agreement between the predicted and actual scuffing resistance was observed
within ±5% significance level.
The Development of a Novel Optoelectronic Level
Authors: Jywe Wen Yuh , Chen Chun Jen
Published: March 2009

Conventional levels can be employed to measure just one dimensional inclinations each time, and are frequently used to measure inclination, straightness and flatness. There are two disadvantages when such levels are used to measure two dimensional inclinations (such as flatness): (1) two measurement steps are needed to measure two orthogonal directions in flatness; and (2) the
two directions cannot be perfectly perpendicular to each other because of setting errors. This paper describes the development of a novel optoelectronic level which employs a simple pendulum, reflection mirror, 2D PSD and laser diode. In this system, a laser light is projected onto reflection mirror 1 which is fixed on a simple pendulum, and mirror 1 reflects the light to mirror 2 which is fixed on a fixture, and mirror 2 reflects the light to the 2D PSD. Thus, the inclination measurement
result can be obtained from the output of the PSD. This paper establishes a novel system and describes the complete experiment. The A-axis rotation angle from approximately -1.3 to 1.3 degrees can be measured with an accuracy of 2 arc sec, and the B-axis rotation angle from approximately -1.7 to 1.7 degrees can be measured with an accuracy of 3 arc sec.
Modeling Analysis of Excimer Laser Crystallization of a-Si Films with Nanosecond Temperature Response
Authors: Chang Chien Hung , Chao Long Sun
Published: March 2009

In the fabrication of a poly-Si film, an a-Si thin layer on glass substrate is melted by the irradiation of an excimer laser with the duration of nanosecond scale, and then is cooled down to form the poly-Si one. For analyzing the fabricating process, an efficient two-dimensional numerical model has been developed in this work, based on the finite difference method and the specific heat/enthalpy method used to handle the release of latent heat. The model can simulate the heat transfer, melt and
solidification behavors of a-Si films subjected to the laser irradiation. Numerical analysis was performed by solving the heat flow equation which incorporates the material properties of temperature dependence, the surface reflectivity of silicon film, the variation of the incident power density with time and heat lose by the radiation and convection from the film surfaces into the surroundings. From the analysis of temperature responses for different laser intensities, the thresholds corresponding to the surface and full melting of the Si film can be found. The temperature
responses are essentially different in the partial-melting and the complete-melting regimes. The Ft (surface melting threshold) and Fc (full-melt threshold) obtained from the simulation results of the proposed model in this study agree fairly well with those from the experimental data reported in the literature. In the partial-melting regime, the maximum temperature is close to the melting point of
amorphous Si, since it is the point where solid a-Si is transformed into liquid state and the high latent heat can absorb extra energy to keep the temperature at the melting point. The fluence larger than Fc is the complete-melting regime, the maximum temperature increases with fluence. It is also found that the variation of the surface reflectivity gives a good way to observe the phase change and the
melting duration. When the a-Si melts, the reflectivity rapidly goes up to a steady value which is consistent with the reflectivity of liquid silicon, and stays there until the melt silicon begins to solidify. As the irradiation energy of laser increases, the melting duration in the silicon layer is prolonged.