bluuebunny/crossref_metadata_2025 huggingface dataset:
Sulfate Crystallization Attack on Cement-Based Materials
Authors: Xie You Jun , Ma Kun Lin , Long Guang Cheng
Published: March 2009

The physical crystallization action of sulfate in cement based material, which often occurs by dry-wet cycle, capillary rising and evaporating action, can damage seriously cement-based materials as compared to chemical corrosion by sulfate. The deterioration mechanism of cement-based materials by sulfate crystallization attack, experimental investigations of the process of sodium sulfate crystallization and the factors affecting the process, and the invading track of salt solution by capillary effect are presented in this paper. Results show that the crystal type and crystallization velocity of sodium sulfate is influenced greatly by relative humidity and ambient temperature. There is a close relationship between invading depth and the porosity of concrete. Addition of mineral admixture to concrete can significantly reduce the invading depth of sodium sulfate solution and thereby enhance the resistance of concrete to sulfate crystallization attack.The profile of invading track of salt solution by capillary effect is similar to the shape of concave parabola.
Modeling Testing of Reinforced Concrete Block Masonry Structures
Authors: Huang Liang , Chen Sheng Yun , Shi Chu Xian , Gao Xiang
Published: March 2009

Integrated simple and complete model similarity theory of this structure are set up in this paper. Selection about model reinforced concrete block masonry materials is presented when simple similar model is adopted in testing. Correlations between model and prototype results in basic strength characteristics of masonry prism are reported based on theory analysis. This includes axial compression, joint shear for ungrouted prisms and grouted prisms. The model testing indicated that the structure adopting simple similarity model can accord with the prototype masonry prisms results. The monotonic shear testing of two-story model reinforced masonry shear wall in different compressive forces was performed. The testing results showed that the model structure can accord with the prototype masonry walls results. The shear bearing capacity of model structure is 0.94 times than that of prototype structure without axial compressive force. The shear bearing capacity of model wall is 1.08 times larger than that of prototype wall when the axial stress equal to 1.5 .Model testing and theory foundation adopting simple similar model is erected to carry out reinforced masonry structure.
Influence of Temperature on the Cracking of Reinforced Concrete Frame
Authors: Lei Jin Song , Yang Dong Sheng , Ying Shan Chuan , Zou Yin Sheng
Published: March 2009

In this paper, the influence of temperature on the cracking of reinforced concrete frame is studied. Finite element analysis software is used to simulate the concrete cracking. In the modeling process, separate model element of SOLID65+LINK8 is used. Also, the Hongestad model is applied to the stress-strain relation of concrete and the rule of BISO is applied to the stress-strain relation of steel. By comparing the stress and strain of three different structure frames before and after temperature increasing, the extending rules of concrete cracking and the stress character of beam and column are analyzed. It is found that the maximum stress of beam is located in the end of the beam-column joints and the middle of beam under the temperature action. It is suggested that they are caused by moment and axis-force respectively. However, the greatest stress of column is situated at the end of beam-column joints. The reason is that the end of beam-column joints should deform to coordinate the influence of temperature. Thus, greater peak stress is caused. So, the concrete cracking is always distributed in the middle of beam span or beam-column joints, where the position of stress concentrates. In addition, the stress of steel in beams increases greatly under the temperature load, suggesting that the temperature leads to the internal force redistribution in the concrete component and the cracking of component.
Preparation and Corrosion of Mullite Thin Film on ß-SiAlON Ceramics
Authors: Noritake Yasunobu , Kiyono Hajime , Shimada Shiro
Published: March 2009

Mullite film was formed on ß-SiAlON (Si6-zAlzOzN8-z, z = 3) ceramics by reaction of Al2O3 films with silica formed on oxidation to improve a high temperature water vapor corrosion resistance. Sintered ß-SiAlON was fabricated by hot pressing of ß-sialon (z = 3) powder without additive at 1900°C and at 24 MPa for 4 h in N2. The Al2O3 film was deposited on polished ß-SiAlON ceramics by a dip coating process of Al2O3 precursor sols prepared from the alkoxide solution and aluminum sol. The Al2O3 coated sample was heated in Ar/O2 (95/5 vol.%) at 1300°C for 2 h, resulting in the formation of mullite by reaction with silica produced from sialon. The resulting mullite-coated sample was corroded in H2O/Ar/O2 (90/8/2 vol.%) at 1200°C for 2 ~ 100 h. The corroded samples were characterized by XRD and SEM-EDS for the evaluation of the corrosion resistance of mullite-coated sialon.
Aqueous Processing of Boron Carbide Powders
Authors: Zhang Jing Xian , Lin Qing Ling , Jiang Dong Liang
Published: March 2009

The present study was performed to determine the suitable processing conditions to obtain boron carbide slurries for gelcasting. We examined how dispersant, pH and other factors function in boron carbide slurries. The optimum conditions for the preparation of stable slurries with high solid content were determined. The effect of monomers on the slurry properties was studied. The properties of gelcasted green and sintered B4C samples were also investigated.
Pressureless Melt Infiltrated Non-Oxide Ceramic-Metal Composites
Authors: Kalemtas A. , Arslan Gürsoy , Kara Ferhat
Published: March 2009

In the present study highly dense (open porosity < 1 %), light-weight (d £ 2.85 g/cm3) and Al4C3-free non-oxide ceramic-metal composites were produced at comparatively low temperatures ( 1250°C) by pressurless melt infiltration. Phase analysis of the SiC-B4C-Al composites revealed that a significant amount of hygroscopic Al4SiC4 and Al4C3 phases were formed. Si3N4 powder was added in different amounts to the SiC-B4C powder batches to suppress formation of these phases via in-situ reactions during the infiltration process. X-ray diffraction results of the SiC-B4C-Si3N4-Al composites confirmed that the incorporation of Si3N4 to the SiC-B4C system reduced or eliminated the formation of the hygroscopic phases and resulted in in-situ formation of AlN, SiC and Si phases in the composite.
Luminescence Properties of α-SiAlONs and Related Compounds
Authors: Xie Rong Jun , Mitomo Mamoru , Hirosaki Naoto
Published: March 2009

-sialon and related compounds have been long known as structural ceramics due to their excellent thermomechanical properties. In this paper, we will present the luminescence of rare earth ions (i.e., Ce3+, Eu2+, Tb3+, Yb2+) in -sialons. The emission of Eu2+ in -sialon related compounds is also summarized. The interesting luminescent properties -sialon and related compounds enable them for use as promising down-conversion phosphors in white light-emitting diodes (LEDs).
Controlled Crystallisation of a Y-Si-Al-O-N Glass Typical of Grain Boundary Glasses Formed in Silicon Nitride-Based Ceramics
Authors: Pomeroy Michael J. , Hampshire Stuart
Published: March 2009

This paper provides an overview of the crystallisation of an oxynitride glass likely to remain in a silicon nitride ceramic following firing. The crystallisation process was studied using both differential thermal analysis (DTA) and separate isothermal heat treatments in a tube furnace under nitrogen. The activation energy for the crystallisation process was determined by DTA. The nucleation temperature, Tg + 40°C, which corresponded to the maximum volume fraction of crystalline phases, agreed closely with the optimum nucleation temperature of Tg + 35°C, found from DTA. The optimum crystal growth temperature was observed to be 1210°C and yielded the - and -polymorphs of yttrium disilicate. Heat treatments at other temperatures indicated the development of phase assemblages which contained different polymorphs of yttrium disilicate as well as silicon oxynitride. Not all of the polymorphic transformations of yttrium disilicate were observed by DTA unless some crystallisation exotherms were deconvoluted, indicating that DTA analysis of the crystallisation of complex systems requires careful interpretation. It is, however, possible to simplify the system by substituting some yttrium by lanthanum. This stabilises the -polymorph of yttrium disilicate. The activation energy for crystallisation was observed to be similar to that for viscous flow of Y-Si-Al-O-N glasses.
Applications of Contact Length Models in Grinding Processes
Authors: Qi H.S. , Mills B. , Xu Xi Peng
Published: March 2009

The nature of the contact behaviour between a grinding wheel and a workpiece in the grinding process has a great effect on the grinding temperature and the occurrence of thermal induced damage on the ground workpiece. It is found that the measured contact length le in grinding is considerably longer than the geometric contact length lg and the contact length due to wheel-workpiece deflection lf. The orthogonal relationship among the contact lengths, i.e. lc2 = (Rrlf)2 + lg2, reveals how the grinding force and grinding depth of cut affect the overall contact length between a grinding wheel and a workpiece in grinding processes. To make the orthogonal contact length model easy to use, attempts on modification of the model are carried out in the present study, in which the input variable of the model, Fn’, is replaced by a well-established empirical formula and specific grinding power. By applying the modified model in this paper, an analysis on the contributions of the individual factors, i.e. the wheel/worpiece deformation and the grinding depth of cut, on the overall grinding contact length is conducted under a wide range of grinding applications, i.e. from precise/shallow grinding to deep/creep-feed grinding. Finally, using a case study, the criterion of using geometric contact length lg to represent the real contact length lc, in terms of convenience versus accuracy, is discussed.
On the Polishing Techniques of Diamond and Diamond Composites
Authors: Chen Y. , Zhang Liang Chi
Published: March 2009

This article reviews the state-of-the-art techniques for polishing diamond and polycrystalline diamond composites. A focus is on their material removal mechanisms and features. It concludes that while each of them has its advantages and drawbacks, the technique by dynamic friction has a promising potential for polishing production.
Influence of Superplasticizer Dosage on Rheological Properties of Fresh Cement Pastes and Properties of Hardened Cement Pastes
Authors: Lin Dong , Lin Yong Quan , Yin Su Hong , Wen Zi Yun
Published: March 2009

The strength and shrinkage properties of mortars with different superplasticizer were studied. The results indicated that the saturation point was the best dosage of superplasticizer, at which it not only helped to reach highest paste fluidity with minimum superplasticizer dosage, but also reach the highest mortar strength and comparatively lower shrinkage rate.
Mix Proportion Optimization and Shrinking of New Developed Reactive Powder Concrete
Authors: Ba Heng Jing , Guo Ai Li , Yan Ying Zi
Published: March 2009

According to the theory of dense packing of particle, the theoretical particle size distribution of raw materials of RPC (Reactive Powder Concrete) was calculated. On the basis, the ratio of raw materials with different range of particle sizes of the RPC was determined by mechanical experiments. According to the determined ratio, a new type RPC was prepared by using flying ash and slag to replace part of cements and quartz flour, respectively. The workability, mechanical properties of the new RPC with different mix proportion and its shrinkage, cured at the normal temperature and 60°C, respectively, were studied. The results show that when water-binder ratio is 0.23, fly ash replaces 30% cements, slag replaces 50% quartz flour and superfine steel fibers percentage in volume is 2%, the compressive and flexural strength of prepared RPC are 160.1MPa and 25.3MPa, respectively, and after 3days heat curing (60°C), the dry shrinkage of it in 28days age reaches 299um/m. In addition, the fluidity of the new RPC is 258mm and meets requirements of workability of the pump concrete.
Design of Lean Manufacturing Support Systems in Make-to-Order Production
Authors: Matt Dominik T.
Published: March 2009

Build-to-order was once the only way in which products were made, but limited the market to only the rich buyers. Mass production contributed to a wider access to products, however with losses in individuality. Finally, mass customization aimed at holding out the promise of both, and “lean” concepts helped to (partly) make it a reality. However, the world has changed significantly since the first introduction of “lean” – especially in the most recent years. European companies are facing a growing international competition in volume markets due to the increasing economical and technical emancipation of low labour cost countries. While multinational enterprises are shifting their manufacturing activities to Far East to keep competitive in terms of costs, small and medium sized companies often have to leave their traditional market segments and retreat into niches. However, smaller production lot sizes and the increasing complexity of product programmes require innovative manufacturing strategies. According to several studies and empirical proves, less than 0,5% of a company’s production lead time is value adding, the bigger part of it is dedicated to waiting, handling and internal transport. This paper presents a new approach for the design of lean manufacturing support systems in make-to-order production systems that have to deal with a huge variety of product types and with high variations in demand. A special focus is given to the design of manual material handling and transport (MMHT) solutions. With the help of axiomatic design principles, a tree of design parameters is derived and translated into generally applicable design rules. With the help of a practical example from make-to-order industry, the validity of the methodology is illustrated.
Application of the Micro-Tensile Testing to Investigate the Adhesion of Thermal Oxide Scales Grown on AISI 441 Stainless Steel Sheet Oxidised in Air and Water Vapour
Authors: Chandra-Ambhorn Somrerk , Nilsonthi Thanasak , Madi Youcef , Galerie Alain
Published: March 2009

A micro-tensile testing has been developed to investigate the adhesion behaviour of the oxide scale thermally grown on AISI 441 stainless steel sheet oxidised at 800 °C in different atmospheres - synthetic air and water vapour. In the test, a sample was placed in a tensile testing machine sitting in the chamber of a scanning electron microscope at room temperature. Evolution of the failure of the oxide scale was monitored in function of the imposed strain. It was found that the scale formed on steel oxidised in synthetic air exhibited the drastically lower spallation ratio in function of strain comparing to the scale on steel oxidised in 20 %v/v H2O/N2. For the sample oxidised in water vapour, it was clearly observed that the scale was primarily failed by the crack perpendicular to the tensile loading direction, followed by the spallation due to the compressive stress generated by the Poisson effect. After the test, precipitates rich in Nb, Si, and possibly Ti were observed at the internal interface between scale and steel substrate. For the oxidised samples that the final polishing direction paralleled to the main sample axis, the strain provoking the first spallation of the samples oxidised in synthetic air and 20%H2O/N2 were 6.23 and 3.52 % respectively. The theoretical model was developed in our previous work to quantify the mechanical adhesion energy. These values were 357 and 68 J.m–2 for the steels oxidised in synthetic air and 20%H2O/N2 respectively.
Roll Forming: Reusable Design and Quantifiable Design Effectiveness
Authors: Mynors Diane J. , English Martin , Castellucci Michael
Published: March 2009

The cold rolled forming process passes flat sheet metal through a series of roll tool sets resulting in complex final section profiles. The sheet metal is deformed both while in contact with the rolls and while in between the roll. Some of the variables in this process include the roll tool set and hence progression design and the designer; the metal type and its thickness; and the sectional profile and the associated tolerances required by the customer.
When a customer orders a new profile the roll tool and hence system designers’, start by trying to determine if something similar has previously been rolled. If a similar profile can be identified then that becomes the starting point for the new process design which includes the roll tool sets and the number of sets. Typically previous designs have been identified from the collective design office memory or by searching through past drawings until something similar is found. When a previous similar rolled section is identified; unless the design is very recent it is often impossible to gauge a measure of design and hence rolling success.
This paper describes how the authors have developed and implemented within the Hadley Group a searchable database of previously rolled profiles, thus enabling all similar profiles to be identified. In addition, the paper contains a description of how a measure of tooling design effectiveness has been developed and is used as part of the full design, pre-production rolling, and full production rolling process with the results being incorporated into the database, hence enabling an informed selection of the design starting point.
Process Variables Optimisation of Polypropylene Based Fibre-Metal Laminates Forming Using Finite Element Analysis
Authors: DharMalingam Sivakumar , Compston Paul , Kalyanasundaram Shankar
Published: March 2009

This study investigates the effect of preheat temperature, blank holder force and feed rate on the formability of polypropylene based Fibre-Metal Laminates. Finite element method combined with Design of Experiments was used to determine the influence of the forming process parameters. The design of experiments was used to identify the relative influence of each process parameter considered in this study. A reduced set of coupled structural-thermal simulations using Ls-Dyna were carried out using a L9 orthogonal array. Simulations were carried out on the forming of domes. It was found that the blank holder force has the greatest influence to increase the minor/major ratios followed by feed rate and pre heat temperature. A more thorough investigation of preheat temperature illustrated an optimum preheat temperature at 130 °C.
Incremental Sheet Forming Analysed by Tensile Tests
Authors: Emmens Wilko C. , van den Boogaard Ton
Published: March 2009

To study material behaviour under conditions encountered in ISF operations tensile tests have been carried out on material taken from the walls of pyramidal products. The shape of the stress-strain curves depend on orientation. Tests in the direction of punch movement show an overshoot indicating a change in strain path, tests across that direction do not. From this it is concluded that the major direction of deformation in the walls is perpendicular to the direction of punch movement. There is no indication of a severe deformation in the direction of punch movement, either stretch or shear. The level of hardening in the material is less than expected from the macroscopic changes in dimensions. Apparently the forming operation in ISF causes additional softening of the material
Investigation of Deformation Phenomena in SPIF Using an In-Process DIC Technique
Authors: Vasilakos Ioannis , Gu Jun , Belkassem Bachir , Sol Hugo , Verbert Johan , Duflou Joost R.
Published: March 2009

Single point incremental forming (SPIF) is a promising new production technique in which a metal sheet is formed stepwise by a spherical tool. However, the technique still shows some particularities. It is observed that the final geometry of a SPIF part can deviate significantly from the programmed tool path. As illustrated in this paper, elastic springback is only to a minor extent responsible for this phenomenon. The goal of the presented paper is to illustrate the gradual emergence of unintended deviations as measured by means of a Digital Image Correlation (DIC) technique. Two CCD cameras were used to take the necessary in-process images. The mechanism of deformation in function of the forming depth is documented and discussed.
Analysis of the Hydraulic Bulge Test with FEA Concerning the Accuracy of the Determined Flow Curves
Authors: Güner Alper , Brosius Alexander , Tekkaya A. Erman
Published: March 2009

This work covers the finite element analysis of geometric and process parameters in hydraulic bulge tests in terms of the accuracy of the evaluated flow curve. The important parameters are identified and varied to cover the whole range of possible uses. The effects of these parameters are analyzed for three representative materials: aluminium, mid-strength steel, and high-strength steel. The flow curves of the materials for each set of parameters are calculated by using the results of the simulations and the membrane theory. It is seen that even with simulation results, it is not always possible to obtain the input flow curve, especially towards the end of the test. The dimensions of the sheet and the tooling affect the plastic strain development and geometry of the bulge, leading to errors in computed flow curves. In order to observe the effect of the material flow from the flange on the determined yield stresses, the function and position of the drawbeads are also examined. These parameters, together with the method used to calculate the radius of the bulge, determine the accuracy of the calculated flow curve. Guidelines for an accurate flow curve determination regarding the test set-up and calculation methods are given.
The Formability of Aluminum Foam Sandwiches: Experimental and FEM Analysis
Authors: D'Urso Gianluca Danilo , Pellegrini Giuseppe , Maccarini Giancarlo
Published: March 2009

This work deals with the formability of metal foams and it is focused on three point bending of aluminum foam sandwich panels. In this study bending can be considered as both a process for shaping of foamed panels and a mean for metal foam testing. Several tests were carried out by varying bending conditions and collecting load-displacement data. Specimens showed an interesting behaviour during bending since the sample deformation was related to the occurrence of foam cells failure or collapse. Moreover, once the process is terminated specimens retained a significant bending strength. During the experimental campaign several samples showed irregular fracture behaviour. In these cases cells fracture often starts in a generic part of the specimen (in correspondence of some non-eligible material defects) and propagates through the foam. The reasons of this problem and the possibility of failure prediction were investigated using different approaches. In particular, thickness measurements (using a ultrasound feeler) and X-ray analysis were carried out for this purpose. In addition, a study based on foam density showed a remarkable data scatter that can be considered as a characteristic of the state of the art in foamed panels manufacturing (in terms of process control and product variability). Finally, load-stroke curves were taken into account for this purpose. Computer simulations of the experiments were performed using the commercial FEM code (Deform 2D). Foam compressibility was simulated using a porous material model and the onset of foam instability was simulated by means of a specific damage criterion. Good agreement between simulative and experimental results was found.
Numerical Prediction of Residual Stresses in Laser Bending of Stainless Steel Sheet Metals
Authors: Gheorghies Constatin , Nicoara Dumitru , Paunoiu Viorel , Quadrini Fabrizio , Santo Loredana , Squeo Erica Anna
Published: March 2009

Stainless steel sheet metals were laser bent by means of a high power diode laser at different values of power and scan velocity. The laser power ranged from 100 to 300 W (with an increment of 50 W); two scan speeds were used, 4 and 8 mm/s, and the number of passes was 2, 4 or 6. In the experimentation, the values of bending angle, microstructure and residual stresses of the laser bended sheet metals were analyzed with regard to the input variables. In particular, residual stresses were evaluated by means of X-ray analysis in terms of first and second order stress. Measurements were performed on the convex surface of the sample in the laser beam action zone. The bending process was numerically simulated by means of a thermo-mechanical finite element model, implemented to predict the sheet metal bending angle as a function of the laser power and scan velocity. The residual stress distribution was extracted from the numerical simulations and its agreement with the experimental observations was discussed. As a general conclusion, the effect of multiple scans is hardly simulated by thermo-mechanical models which do not take into account the material annealing during forming.
Yb:YAG Disc Laser Welding of Austenitic Stainless Steel Without Filler Material
Authors: Keskitalo Markku , Mäntyjärvi Kari
Published: March 2009

The laser weldability of austenitic stainless steel (ASS) is good because of the material’s high absorptivity and favourable microstructure. There can be a slight possibility of solidification cracking at high welding speeds and low Crekv/Niekv ratios. Test welds were welded with a Yb:YAG disc laser. The test material was 3.2 mm EN 1.4404 2H C700 type stainless steel plate which was work hardened by cold rolling. The test materials were welded with different heat inputs ranging from 0.024 kJ/mm to 0.12 kJ/mm and with 300 mm and 200 mm focal lengths. The weld seams were square-groove welded as butt weld without filler material. The edges of the groove were made by mechanical or laser cutting. The hardness profiles from cross-sections of the welds were measured with a Vickers microhardness tester using 200 g weight. The mechanical properties were tested with tensile tests. The welds were classified with radiographic verification by an accredited laboratory. A number of the welds were fatigue tested with a bending fatigue tester. The mechanical properties (Rp 0.2%, Rm) of the laser welds were almost the same as in the base material except at the highest heat input. In the radiographic classification, the welds which were welded to the laser-cut edge were classified as class B (accepted). The other welds were classified as class D or C (rejected). The main reasons for the rejection of welds made on mechanically cut edges were lack of penetration or undercut of the weld. A problem with mechanically cut edges, and hence the welds, is that they can be non-square and bent edge. Fatigue tests and tensile tests gave no evidence of solidification cracking in the microstructure of the solidified parts of the welds.
Texture Inheritance in a Zn Protective Layer
Authors: Bonarski Jan T.
Published: March 2009

Crystallographic texture is one of frequently investigated properties of near-surface
regions. From the application point of view, the inheritance effect of the crystallographic orientation of a substrate is important for layered structures. The investigation of the texture of layered structures or gradient materials by means of X-ray diffraction back-reflection pole figure measurements requires a control of the information depth. Such measurements at a controlled information depth can be achieved by means of non-symmetrical diffraction geometry, employing a
constant value of falling angle of the incident beam.
Thus, the texture of near-surface layers with a defined thickness can be examined, as in tomographic techniques. In this work, the method of texture analysis based on a controlled information depth was applied to the investigation of the texture inheritance of a Zn protective layer on deep drawing steel. Moreover, the crystallographic relations between the texture of substrate and deposited layer,
termed as texture inheritance, were considered.
Photocatalytic Activity of SiO2-TiO2 Nanoparticles Prepared by Sol-Hydrothermal Process
Authors: Whang Chin Myung , Kim Y.K. , Kim J.G. , Lee Wan In , Kim Y.
Published: March 2009

[SiO2]x[TiO2]1-x(x = 0.1, 0.2, 0.3, 0.4) powders were prepared by hydrothermal reaction of titanium
isopropoxide (TIP) and tetraethyl-orthosilicate (TEOS) stabilized in acidic ethanol/water solution.
The size and phase of TiO2 particles were controlled by adjusting the SiO2 content and the
composition of the solvent system. The microstructure and photocatalytic activity of the prepared
SiO2-TiO2 nanoparticles were characterized by XRD, TEM, BET, Raman and UV visible
spectroscopic techniques. The major phase for all the prepared samples was anatase.
The particle size of 0.3SiO2-0.7TiO2 powders prepared with excess amount of ethanol (REtOH =
EtOH/alkoxide molar ratio = 120) was about 8.7 nm, while that of the sample prepared with small
amount of ethanol (REtOH = 4) was 9.9 nm. The photocatalytic activity of these composite powders
under excess ethanol was 1.5 times higher than that of pure TiO2 with respect to the decomposition
of 1,4-dichlorobenzene (DCB).
Prediction of the Structural Performances of ZnO Nanowires Grown on GaAs (001) Substrates by Metalorganic Chemical Vapour Deposition (MOCVD)
Authors: Lee W. , Sohn H.G. , Myoung Jae Min
Published: March 2009

Application potential of ZnO nanowires grown by MOCVD for atomic force microscope
(AFM) probes was evaluated by predicting numerically their structural performances in terms of
flexural stiffnesses and natural frequencies. Estimated properties of the nanowires suggested that they
are structurally compatible with typical AFM cantilevers while maintaining mechanical stability
during operation and they are therefore promising candidates for high aspect ratio probes.
Fabrication of Copper Clad Aluminum Wire (CCAW) by Indirect Extrusion and Drawing
Authors: Kwon Hyouk Chon , Jung Taek Kyun , Lim Sung Chul , Kim Mok Soon
Published: March 2009

The optimized extrusion conditions from the present research were the extrusion
temperature of 573~623K and the extrusion ratio(A0/A) of 21.39. Above the extrusion temperature of 623K, the fracture of sheath material was observed. It is due to the difference of flow stress between the sheath material and the core material during extrusion process. The bonding strength increased with increasing the extrusion temperature and the extrusion ratio. The bonding strength increased with increasing the annealing temperature. However, over 573K, it decreased abruptly since the thick and brittle intermetallic compounds of larger than 3µm were formed. The electricalconductivity of copper clad aluminum wire was about 70%IACS without annealing.
Ultra Grain Refinement and High Strengthening of Al Based MMC by Accumulative Roll Bonding Process
Authors: Lee Seong Hee , Lee Chung Hyo , Chang Si Young
Published: March 2009

Aluminum based metal matrix composite (MMC) was processed by accumulative roll bonding (ARB) for ultra grain refinement and high strengthening. The ARB process up to 4 cycles was performed for the composite with 5vol.%SiC at ambient temperature under unlubricated conditions. The ARB of unreinforced aluminum powder compact was also performed for comparison. The tensile strength of the composite increased with the number of ARB cycles, and reached a maximum of 375MPa at the 3rd cycle, which is 1.8 times higher than that of the initial material. An increment of the strength per cycle was much larger in the composite than that in the unreinforced 6061 aluminum powder compact. The elongation of the composite decreased gradually with the number of ARB cycles, became almost zero after 4 cycles. TEM observation revealed that the composites fabricated by 1 to 3 cycles showed a dislocation cell structure, but after 4 cycles it showed an ultra-fine grained structure with mean grain size below 500nm. The ultra-fine grains developed at lower cycles in the composite than in the unreinforced one.
Tensile Properties of Cast and Hot Isostatic Pressurized Ti-6Al-4Fe-xSi Alloys
Authors: Kim E.H. , Jeong Hi Won , Kim Seung Eon , Hyun Yong Taek , Lee Yont Tai , Yoon Jong Won
Published: March 2009

A new high strength titanium alloy system with low cost alloying elements, such as Al,
Fe, has been recently developed. In present study the expensive V was replaced with Fe, and Si was added from 0 to 7.5wt.%. The effect of Fe and Si on the microstructure and tensile properties of Ti-6Al-4Fe-xSi (x=0, 0.1, 0.25, 0.5, 0.75wt.%) alloys was investigated. The room and high temperature mechanical properties of Ti-6Al-4Fe alloys were better than those of the Ti-6Al-4V. It was mainly due to the phase boundary strengthening at ambient and high temperature. The strength and elongation of the developed alloys depended upon the Si contents. The Si elements made the grain boundary and colony size fine, and increased the strength of the developed alloys by solid solution and precipitation hardening. The tensile strength variation with the Si contents at room temperature and 400°C, and at 450°C and 500°C showed a similar behavior, respectively.
High Temperature Oxidation of Ti39.4Al10V Alloy
Authors: Lee Dong Bok , Jang Y.D.
Published: March 2009

Alloys of Ti39.4Al10V (at.%) that consisted mainly of ordered β-Ti, γ-TiAl and α2-Ti3Al phases were oxidized at 700, 800, 900, and 1000oC in air. The oxide scales formed consisted largely of an outermost, thin TiO2 layer, an outer, thin Al2O3 layer, and an inner, very thick (TiO2+Al2O3) mixed layer. Vanadium, which was uniformly distributed throughout the oxide scale, harmfully decreased oxidation resistance, and made thick, nonadherent scales owing to the formation of low melting compounds of V-oxides. The oxidation progressed via the outward diffusion of Ti, Al and V ions, and the concurrent inward transport of oxygen.
Ductile-Brittle Transition Behaviors with Two Striker Geometries in the Instrumented Charpy Impact Test
Authors: Morita Shigeki , Kobayashi Toshiro
Published: March 2009

Instrumented Charpy impact test method is possible to obtain various dynamic fracture characteristics from the load-deflection or load-time curve. Recently, instrumented Charpy impact test method is widely used for the evaluation of toughness of various specimens of different materials with different sizes. It is important to record an accurate impact load in order to improve the reliability of this test method. In some standards of instrumented Charpy impact test method such as ISO and ASTM, they haven.t clearly standardized striker geometry which seem to directly influence the obtained impact load. There are some differences between standards, although standard procedures are well defined. Therefore, instrumented Charpy impact test method has a problem that measurement value is different depending on each standard.
In the present study, the effect of striking edge geometries, which are difference between ISO and ASTM, on load-deflection curve and absorbed energy were investigated. According to ISO and ASTM, two types of striker having different radius were machined. There was no difference between the two different striking edge geometries for values of absorbed energy per unit ligament area less than 0.75J/mm2. However, striking edge geometry according to ASTM is not propriety for Charpy impact test method because of four, instead of three, point bending on process of fracture at high level of absorbed energy. The effect of brinelling deformation, which was considered as an advantage of striking edge geometry according to ASTM, is very small on instrumented Charpy impact test. Consequently, there seem to be not an advantage of striking edge geometry according to ASTM. Therefore, standards should be unified in the striking edge geometry according to ISO.
Stress Relaxation Measurements of Meta-Dynamic and Static Recrystallization of Alloy 80A
Authors: Kleber Siegfried , Sommitsch Christof
Published: March 2009

The stress relaxation method has been applied to the nickel-based alloy 80A to predict meta-dynamic (MDRX) and static recrystallization (SRX) kinetics. Compression tests were performed on a Gleeble 3800 system atr different temperatures (950-1200°C). The strain rate was varied in the case of MDRX and the pre-strain in the case of SRX. To investigate MDRX, the prestrain was set to twice the peak strain in order to reach steady state before holding. To focus on the interaction of MDRX and SRX, the pre-strain was set to the peak strain, where dynamic recrystallization (DRX) starts but does not yet reach steady state. Avrami type equations for the prediction of both the MDRX and SRX were adapted to feed a semi-empirical grain structure model.
Self-Annealing Textures of Copper Damascene Interconnects
Authors: Lee Dong Nyung , Lee Hyo Jong
Published: March 2009

The properties of deposited metal films and interconnect structures at submicrometer scale are sensitive functions of microstructural features. Therefore, understanding of the factors which control microstructural evolution is necessary for the development and design of reliable, manufacturable interconnect structures, especially in copper damascene interconnects. The annealing textures of copper interconnects depend on their deposition textures and geometries. The copper interconnects are subjected to stresses even at room temperature, which in turn give rise to strain energies. The stress distributions in interconnects are not homogeneous, which in turn give rise to non-fiber type textures after annealing. The self-annealing textures of interconnects is discussed based on the strain-energy release maximization model, in which grains whose Young’s modulus direction is parallel to the absolute, maximum stress direction grow in preference to others.
Three-Dimensional Micron-Resolution X-Ray Laue Diffraction Measurement of Thermal Grain-Evolution in Aluminum
Authors: Budai J.D. , Yang W. , Larson B.C. , Tischler J.Z. , Liu W. , Weiland Hasso , Ice Gene E.
Published: March 2009

A new technique for investigating 3D grain growth in polycrystalline materials using
white x-ray microdiffraction with micron point-to-point spatial resolution is presented. This technique utilizes focused polychromatic x-rays at the Advanced Photon Source, differential aperture depth-profiling, CCD measurements, and automated analysis of spatially-resolved Laue patterns to measure local lattice structure and orientation. 3D thermal grain growth studies of hotrolled aluminum have been initiated to demonstrate the capabilities of this method. Complete 3D grain orientation maps were obtained from a hot-rolled aluminum polycrystal. The sample was then annealed to induce grain growth, cooled to room temperature, and re-mapped to measure the thermal migration of all grain boundaries within the same volume region. Initial observations reveal significant grain growth above 360°C, involving movement of both low- and high-angle boundaries. Systematic measurements have been obtained of the as-rolled grain structure and of the microstructural evolution after annealing at successively higher temperatures. Small second-phase precipitates have been identified. Such measurements will provide the detailed 3D experimental
link needed for testing theories and computer models of 3D grain growth in bulk materials.
Micro-Scale OIM Study on the Recrystallization Process of Cold Rolled α-Fiber Single Crystal
Authors: Nakamura Shuichi , Homma Hotaka
Published: March 2009

Recrystallization of cold rolled {211}<011> single crystal of 3.5%Si-Fe were investigated by electron back-scattered pattern (EBSP) technique in order to clarify the formation of {h,1,1}<1/h, 1, 2> fiber in recrystallization texture of steel with high cold rolling reduction. In the cold rolled sample, there exist shearband
like substructures characterized by the orientation fluctuation with single <011> axis whereas their orientations are almost kept to the original orientation {211}<011> which belongs to a-fiber (RD//<110> fiber). In the recovery stage, the orientation fluctuations are enhanced and include fluctuations with another <011> axis. That is the fluctuations in recovery stage are not characterized by rotation relationship with single <011> axis. The recrystallization texture includes {100}<012> and {411}<148> as major orientations in {h,1,1}<1/h, 1, 2> fiber. Furthermore, there exists clear orientation relationship characterized by multiple rotations with <011> axes between the recrystallization orientations and the original one. Actually, orientations characterized by rotational relationships with <211> (=[110]+[101]) axis and <111> (=[110]+[101]+[011]) were observed. These results suggest that recrystallization from a-fiber is occurred as a result of the final enhanced stage of the fluctuations characterized by multiple rotations with <011> axes.
Evaluation of Selective Growth in a Fe-2.8%Si Single Crystal Using Rodrigues-Frank Space
Authors: Verbeken Kim , Kestens Leo , Nave Mark D.
Published: March 2009

A Fe-2.8%Si single crystal was scratched in order to randomise the texture in the
neighbourhood of the notch. Annealing resulted in recrystallization and grain growth starting from the deformed zone. Misorientations between the single crystal matrix and the grown grains were gathered and were studied in order to investigate the possibility for selective growth based on a specific misorientation. However, instead of studying the misorientation angle or axis profiles separately in a 1D or 2D projection a full misorientation analysis was carried out in the 3-dimensional Rodrigues-Frank misorientation space, which offers an unambiguous interpretation
of the data because no features are hidden or masked by a projection. It is concluded that the selective growth phenomenon following the <110>26.5deg misorientation relationship is strongly supported by the gathered orientation data, after appropriately normalizing these data with respect to a random misorientation distribution.
On {h,1,1}<1/h,1,2>, the Recrystallisation Texture of Heavily Cold Rolled BCC Steel
Authors: Homma Hotaka , Nakamura Shuichi , Yoshinaga Naoki
Published: March 2009

Heavily cold rolled BCC steel has been indicated to generate {411}<148> recrystallisation texture and its family orientations which might be represented as {h,1,1}<1/h,1,2>. As a-fibre structure, or RD//<011> texture is significantly developed during the cold rolling, it is naturally speculated to be the recrystallisation site of {h,1,1}<1/h,1,2> fibre. The present paper prompts to demonstrate the recrystallisation procedure by utilising EBSP-OIM analysis. The first demonstration was carried out with OIM analysis on partially recrystallised cold rolled steel. At the stage of 50% recrystallisation, only ND//<111> texture has appeared for the recrystallised area. {100}<011> - {211}<011> a-fibre remains as deformed structure, and several {h,1,1}<1/h,1,2> grains could be found at the grain boundaries. Therefore, a bi-crystal of {100}<011> was employed to simulate the irregular deformation at the grain boundary. After cold rolling, a warp toward the grain boundary was observed. Although the interior of the {100}<011> single crystal was hardly recrystallised, sharp {411}<148> texture was created along the grain boundary. In order to confirm the phenomenon, another experiment was carried out that a cold rolled {100}<011> single crystal was bent along the rolling direction and annealed. Very sharp {411}<148> recrystallisation texture was formed again at the bent perimeter. These experimental results lead us to conclude that the irregular strain was sufficiently piled at the grain boundary after the heavy deformation and generates {h,1,1}<1/h,1,2> texture. On {100} pole figures, the recrystallisation textures were equivalently scattered around three <100> poles, therefore the rotation relationship around <111> axes with the original orientation was suggested.
Industrial Application of Recrystallization Control in Aluminum Products
Authors: Weiland Hasso
Published: March 2009

Engineering properties of aluminum alloys can be optimized by a combination of thermomechanical processes. For example, a series of deformation and recrystallization processes is used to improve the deep drawing characteristics of aluminum sheet for beverage can fabrication or the forming characteristics in automotive applications. In other cases, suppression of recrystallization is desired: fracture toughness of high strength aluminum alloys is better for an unrecrystallized material than for a recrystallized material of comparable yield strength. Industrial control of recrystallization mainly focuses on control of texture for formability, control of grain size and degree of recrystallization for surface appearance and damage related properties. Such control is achieved by manipulating nucleation and growth of new grains. Nucleation density and crystallographic orientation of new grains is determined by inhomogeneities of the deformed structure. Grain boundary mobility is controlled by second phases, which at the correct size will exert a pinning force on the boundary. Additionally, solutes impose a drag on moving grain boundaries. The following will review the various applications of recrystallization in manufacturing of wrought aluminum products, summarize the current understanding of recrystallization processes in aluminum alloys, and point out needs for further understanding and necessary requirements for simulation of recrystallization processes.
Development of Grain Structure and Texture during Annealing in Asymmetrically Rolled AA5754
Authors: Jin Hai Ou , Lloyd David J.
Published: March 2009

AA5754 sheet has been processed by asymmetric rolling and the development of grain structure and texture in subsequent annealing studied at 240-500°C. It has been found that asymmetric rolling facilitates the formation of ultra-fine grain structure (1-2µm grain size) by shear strain promoted continuous recrystallization, which is a process of extended recovery and subgrain/grain growth. The ultra-fine grain structure is not thermally stable, and when the annealing
temperature or time increases, the grain size eventually grows to its Zener limit. The deformation texture is similar to the typical f.c.c. cold rolling texture but rotated about the transverse direction. Along with the formation of an ultra-fine grain structure and subsequent grain growth, the deformation texture is retained.
Cellular Automata Simulation of the Effect of Nuclei Distribution on the Recrystallization Kinetics
Authors: Rios Paulo Rangel , Carvalho J.J.S. , Salazar T.C. , Paula F.V.L. , de Castro José Adilson
Published: March 2009

Analytical modeling of recrystallization considers two arrangements of nuclei: a) random, b) “periodic”. If nucleation departs from these extremes, no exact analytical treatment is available. When classical Johnson-Mehl, Avrami, Kolmogorov approach is used there is often the doubt whether the nucleation is truly random. Therefore, it would be of some interest to assess to what extent the exact analytical theory is valid if the nucleation departs from randomness. In this work, recrystallization is simulated using cellular automata in two dimensions in order to investigate the effect of nuclei distribution on the kinetics. Simulations are carried out for nuclei distribution ranging from periodic to random. The effect of departure from the exact analytical solutions is assessed by means of the overall kinetics and the microstructural path.