bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical Properties and Microstructures of Severely Plastic Deformed Pure Titanium by Mechanical Milling and Spark Plasma Sintering
Authors: Kubota Masahiro , Ohno Takuya
Published: December 2010

Severe plastic deformation (SPD) was applied to pure titanium powder by mechanical milling (MM) process with stearic acid, added as a process control agent (PCA), by using a vibrational ball mill, and MMed powders possessing large strains were subsequently consolidated into bulk materials by spark plasma sintering (SPS) in order to enhance the hardness and strength of pure titanium. Changes in the hardness and constituent phases of the MMed powders have been examined by microhardness measurements and X-ray diffraction. The hardness and microstructure of the SPS materials have also been studied by hardness measurements and optical microscopy. The Vickers microhardness of the pure titanium powders with PCA 0.25 g increased sharply from 189 HV to 513 HV after 8 h of the mechanical milling (MM) process. Formation of TiH2 as the solid-state reaction product occurred in the MMed powder during 4 and 8 h of the MM process. The near full density was obtained for the SPS materials under the condition of an applied pressure at 49 MPa with a sintering temperature at 1073 K for 0.5 h. The Vickers hardness of the SPS material fabricated from 8 h MMed powder with PCA 0.50 g exhibited a maximum value of 1253 HV.
Comparison of Different Extrusion Methods for Compaction of Powders
Authors: Molotnikov Andrey , Lapovok Rimma , Peng Tao , Estrin Yuri
Published: December 2010

Densification of metallic powders by means of extrusion is regarded as a very attractive processing technique that allows obtaining a high level of relative density of the compact. However, the uniformity of the relative density depends on that of strain distribution and on the processing parameters. Several variants of extrusion can be used for compaction of metal particulates, including the conventional extrusion (CE) and equal channel angular pressing (ECAP), often referred to as equal-channel angular extrusion. Each of these processes has certain advantages and drawbacks with respect to compaction. A comparative study of these two extrusion processes influencing the relative density of compacts has been conducted by numerical simulation using commercial finite element software DEFORM2D. The results have been validated by experiments with titanium and magnesium powders and chips.
Grain Refinement and Dispersion Precipitation of I-Phase in Mg-Zn-Y Alloy Processed by ECAP
Authors: Min Guang Hui , Cui Hong Wei , Lu Qing Liang , Gao Pan , Yu Hua Shun
Published: December 2010

Equal channel angular pressing (ECAP) has been conducted on as-extruded Mg-Zn-Y alloy containing quasicrystal phase at a temperature of 523 K. The optical images indicate that after 8 ECAP passes through route BA, the grain size of the extruded alloy is decreased sharply; and the coarse eutectic icosahedral quasicrystal phases (I- phases) are broken and dispersed in the alloy; and the distributions of Zn and Y elements become more homogeneous. These can be attributed to the shear effect during the ECAP processing. TEM micrographs show the grain refinement, the evolution of broken and dispersed I- phases and dispersion precipitation of nano I-phases during 1- ,4- and 8- pass ECAPed Mg-Zn-Y alloy. And the mechanism of grain refinement is also discussed.
Effect of Asymmetrical Accumulative Roll-Bonding and Heat Treatment on the Formation of Ultra-Fine Twin Copper
Authors: Mi Hui , Shi Qing Nan , Wang Jun Li , Zhou Lei , Chen Liang Wei
Published: December 2010

The ultrafine copper with twins was prepared by asymmetrical accumulative roll-bonding (AARB) and heat treatment. The characteristic of grain refinement and the texture transformation during recrystallization were investigated. The results show that the crossover areas, which were formed by the shear stress during AARB, were zones of compression deformation and shearing deformation when the deformation of copper occurred in these areas. The average grains size was reduced to 1μm from original average size of 30～50μm due to processing by AARB. The strong elastic stress accumulated by shearing texture is responsible for oriental growing of a great number of grains during recrystallization. The shearing texture {001}<110> rotates 54.7°and transforms into annealing texture {111}<211> i.e. twins microstructure.
Nanostructured Dual Phase Ti-Al through Consolidation of Particles by Severe Plastic Deformation
Authors: Lui Edward W. , Xu Wei , Xia Kenong
Published: December 2010

A two-phase Ti-Al material was fabricated by severe plastic deformation. Particles of finely mixed elemental Ti and Al were mechanically milled and then consolidated by equal channel angular pressing. The bulk material has a unique interpenetrating structure of Ti and Al phases with multiple scales from micro to nano. Compared to its coarse structured counterpart, the multiscale structured material exhibited a significant increase in strength without compromising plasticity.
Correlation of Physical Parameters with Steady-State Hardness of Pure Metals Processed by High-Pressure Torsion
Authors: Edalati Kaveh , Horita Z.
Published: December 2010

Pure metals of 30 elements with various crystal structures (bcc, fcc, hcp, diamond cubic, complex cubic, primitive hexagonal and tetragonal) are processed by high-pressure torsion (HPT) and their mechanical properties are subsequently evaluated by Vickers microhardness measurements. For all metals, the hardness reaches steady states at large strains where the hardness remains unchanged with further straining. It is shown that the hardness values at the steady state are characteristics of each metal and are successfully expressed as a unique function of the homologous temperature, shear modulus and physical parameters of metals such as melting temperature, specific heat capacity and diffusion coefficient except for a few elements. The findings are well applicable to predict the ultimate steady-state hardness of metals attained by HPT processing through the correlation established in this study.
Strain Rate Sensitivity of Ultrafine-Grained CP-Ti Processed by ECAP at Room Temperature
Authors: Liu Xiao Yan , Zhao Xi Cheng , Yang Xi Rong
Published: December 2010

Ultrafine-grained (UFG) commercially pure (CP) Ti with a grain size of about 200 nm was produced by ECAP up to 8 passes using route BC at room temperature. For ECAP processing a proper die set was designed and constructed with an internal channel angle Φ of 120° and an outer arc of curvature Ψ of 20°. Strain rate sensitivity of UFG CP-Ti and CG CP-Ti were investigated by compression tests in the temperature range of 298~673K and strain rate range of 10-4~100s-1 using Gleeble simulator machine. Evolution of the microstructure during compression testing was observed using optical microscopy (OM) and transmission electron microscopy (TEM). Strain rate sensitivity value m of the UFG CP-Ti has been measured and is found to increase with increasing temperature and decreasing strain rate, and is enhanced compared to that of CG CP-Ti. Result of the deformation activation energy determination of UFG CP-Ti indicates that the deformation mechanism in UFG CP-Ti is correlated to the grain boundaries.
Mechanical Properties of Different Coppers Processed by Equal Channel Angular Pressing
Authors: Higuera Oscar Fabián , Muñoz Jairo Alberto , Cabrera Jose María
Published: December 2010

Mechanical properties of two Cu alloys (electrolytic and fire refined) severely deformed by equal channel angular pressing (ECAP) process were investigated. They were treated with a annealing heat treatment to 600°C during 30 minutes and then they were extruded in a Φ=90º ECAP die at room temperature following route Bc. Heavy deformation was introduced in the samples after a considerable number of ECAP passes from 1, 2, 3, 4, 5, 6, 7, 8, to 16. The principal changes were introduced in the first pass by ECAP but a gradual increment in the mechanical properties was observed for the consecutive ECAP passes. Also, the electrical conductivity decreased with increasing numbers of ECAP passes.
Influence of Nanoparticle Reinforcement on the Mechanical Properties of Ultrafine-Grained Aluminium Produced by ARB
Authors: Schmidt Christian W. , Knieke Catharina , Maier Verena , Höppel Heinz Werner , Peukert Wolfgang , Göken Matthias
Published: December 2010

Dispersed nanoparticles are introduced from stabilized suspensions during the accumulative roll bonding process in aluminium AA1050A by air gun spraying up to a final volume fraction of 0.1 % after eight cycles. Additional strengthening caused by particle insertion is observed and strongly depends on the suspension medium and stabilizing agent as both influence interfacial bonding of the particles to the matrix. The particle insertion furthermore results in reduced peel strength of the sheets irrespective of particle material and size caused by a reduction of effective metal to metal bonding area during rolling through the presence of the particles.
Influence of Severe Plastic Deformation and Ageing on the Microstructure and Mechanical Properties of β-Alloy Ti-6.8Mo-4.5Fe-1.5Al
Authors: Semenova Irina P. , Medvedev Alexander
Published: December 2010

This work presents the possibility of strength enhancement in the -alloy Ti-6.8Mo-4.5Fe-1.5Al via equal channel angular pressing at room temperature without precipitation of a secondary -phase. Influence of the initial structure of the alloy and ageing temperature on the density of precipitations and dimensions of the secondary -phase is revealed. It has been stated that combination of the solid solution treatment with the subsequent ECAP processing and final ageing is an effective way to achieve superior strength and ductility.
Strengthening of CP-Ti by Rolling at Room Temperature
Authors: Jiang Jian Hua , Ding Yi , Shan Ai Dang
Published: December 2010

The effects of asymmetric and symmetric rolling at room temperature on mechanical properties and microstructure of the commercial purity Ti were investigated by means of mechanical test, optical microscopy, X-ray diffraction and transition electron microscopy. The results show that through asymmetric and symmetric rolling processes the ultimate tensile strength is substantially increased from 450 MPa to 960 MPa. Microstructure observation illustrates this variation in mechanical property is caused by the grain refinement and work hardening.
Mechanisms of Deformation Behavior of Coarse-Grained and Ultrafine-Grained Ti
Authors: Alexandrov Igor V. , Chembarisova Roza G.
Published: December 2010

A grain size is known to be one of the factors which define mechanical properties of metallic materials. At the same time the mechanisms which regulate the deformation behavior of bulk ultrafine-grained (UFG) metals produced by the severe plastic deformation method are still a subject for intensive study and fixed ambiguously. The report presents the developed model and the results of its application for kinetic modeling of the deformation behavior of coarse-grained (CG) and UFG Ti. Modeling has been carried out considering the possible contribution of dislocation slip and ageing. Conclusions about the role of the investigated mechanisms in the appearance of the peculiarities of the deformation behavior of CG and UFG Ti have been made.
Evolution of Adiabatic Shear Band in Ultra-Fine-Grained Iron under Dynamic Shear Loading
Authors: Yuan Fu Ping , Wu Xiao Lei
Published: December 2010

Ultra-fine-grained (UFG)/Nanocrystalline (NC) materials usually show reduced strain hardening and limited ductility due to formation of adiabatic shear band (ASB) under dynamic loading. In the present study, evolution of ASB in UFG Fe under dynamic shear loading was investigated. The UFG Fe was processed by equal-channel angular pressing (ECAP) via route Bc. After 6 passes, the grain size of UFG Fe reaches ~ 600 nm, as confirmed by means of Electron Back Scatter Diffraction (EBSD). Examination of micro-hardness and grain size of UFG Fe as a function of post-ECAP annealing temperature shows a transition from recovery to recrystallization at 500 0C. The high-strain-rate response of UFG Fe was characterized by hat-shaped specimen set-ups in Hopkinson bar experiments. The characteristics of ASB as a function of shear displacement, such as thickness of shear band and micro-hardness inside the shear band, were examined by SEM and Vickers micro-indentation respectively.
Using Atomic Force Microscopy to Examine Flow Processes in Materials Processed by ECAP
Authors: Huang Yi , Langdon Terence G.
Published: December 2010

Atomic force microscopy provides a useful tool for examining the flow processes occurring during the tensile testing of ultrafine-grained metals processed by equal-channel angular pressing (ECAP). This paper describes the results obtained from experiments conducted on a Zn-22% Al eutectoid alloy and high-purity (99.99%) aluminium. The results show these two materials behave in different ways in terms of the development of mesoscopic shear planes.
CP-Ti Processed for Multiple Passes by ECAP at Room Temperature
Authors: Yang Xi Rong , Zhao Xi Cheng , Liu Xiao Yan
Published: December 2010

A series of experiments were conducted to evaluate the feasibility that commercially pure titanium (CP-Ti) was pressed for multiple passes by equal channel angular pressing (ECAP) at room temperature. Samples of CP-Ti were processed at room temperature using the dies with channel angles of 90° and 120°, respectively. First, each billet was processed 4 passes by ECAP using a die with an angle of 120° and a ram speed of 0.5mm s-1. And in order to eliminate residual stress, immediate annealing at 473 K for an hour was conducted between two adjacent passes. Second, CP-Ti was successfully processed by ECAP for up to 8 passes using the same die and a ram speed of 2 mm s-1 by controlling the flow of metal. Finally, CP-Ti was successfully achieved using a conventional die with an angle of 90° between the channels at room temperature. Each billet was processed for two passes with a ram speed of 26 mm s-1. These experiments show that CP-Ti may be processed by ECAP at room temperature and special attention was paid on improvements in the yield stress, ultimate strength and micro-hardness of ECAPed-Ti that are slightly higher than the improvements attained after pressing at elevated temperatures.
Influence of the SPD Processing Features on the Nanostructure and Properties of a Pure Niobium
Authors: Kommel Lembit A. , Mikli V. , Traksmaa R. , Saarna M. , Pokatilov Andrei , Pikker S. , Kommel I.
Published: December 2010

The structurization of a high purity niobium from double electron-beam melted cast microstructure to fine-grained microstructure was completed by equal-channel angular pressing by the Bc route up to a Von Mieses strain of 13.8. In addition, for the viscoplastic behavior study as well as nanostructure and properties improving the hard cyclic viscoplastic deformation, die forging at room temperature and followed heat treatment with low heating rate were conducted. The nanostructure of processed samples was characterized by transmission electron microscopy and X-ray diffraction testing. This paper focuses on several new trends in the study of improved mechanical and physical properties of pure niobium, to what purpose these materials will be used in industry. The crystallite size, microstrains and dislocation density in severe plastic deformed pure niobium were calculated and electric conduction was measured. The nanocrystalline microstructure with minimal crystallite size down to 62 nm as mean in cross-section of sample was received. By this the dislocation density varies from 5.0 E+10 to 2.0 E+11 cm-2 and was maximal for pure niobium which has minimal electrical conductivity, maximal value of hkl-parameter and maximal relative microstresses. The microhardness was maximal for sample after 12 passes by Bc route and for samples with 8 and 10 passes followed heat treatment at 170 and 350°C. The mechanisms answerable for the electronic conduction were discussed according to the microstructure evolution in the different directions and for different strain levels.
Temperature Effects on the Mechanical Behavior of Ultrafine-Grained Material
Authors: Suo Tao , Li Yu Long , Zhao Feng , Xie Kui
Published: December 2010

The quasi-static and dynamic compression experiments of ultrafine-grained copper fabricated by equal channel angular pressing method were performed at temperatures ranging from 77 to 573K. The influence of temperature on flow stress, strain hardening rate and strain rate sensitivity were investigated. The results show that the flow stress of ultrafine-grained copper shows much larger sensitivity to testing temperature than that of coarse grained copper. However, the temperature sensitivity of ultrafine-grained copper to true strain is comparative weaker than that of coarse grained copper. For the ultrafine-grained copper, both the strain hardening rate and its sensitivity to temperature of ultrafine-grained copper are lower than those of its coarse counterpart. The SRS also displays apparent dependence on temperature. The activation volume for UFG-Cu is estimated to be on the order of ~10b3 in current experiment temperature. It is suggested that the dislocation-grain boundary interactions process might be the dominant thermally activated mechanism for UFG-Cu.
Static and Cyclic Deformation of Commercially Pure Al Processed by Equal-Channel Angular Pressing Using Two Routes
Authors: Soliman Mahmoud S. , El-Danaf Ehab , Almajid Abdulhakim A.
Published: December 2010

In the present investigation, annealed billets of commercially pure Al (1050) with coarse-grained microstructure of 0.6 mm were ECAPed through a die with an internal angle of 90o using two routes A and BC. The samples were processed up to four passes using both routes. The change in the processing route results in the change of the shear plane, and consequently the change in the produced microstructure. The microstructure study was conducted on the extrusion direction and the shear plane. The cell size, misoriention and the fraction of high angle boundaries were determined by using electron back scattered diffraction (EBSD). A study of mechanical behavior was conducted by cutting tensile and compression specimens from the ECAPed specimen in the extrusion direction to study the effect of processing route and the number of passes on the deformation characteristics. Enhanced strength was observed but with anisotropic behavior between tension and compression. Cyclic deformation under load control (HSF) was also performed and the S-N curves were established as a function of number of passes and processing route. The fractography of fractured tensile specimens was also investigated.
Comparison of High-Temperature Compressive Deformation Characteristics of Differently Processed LY12 Aluminum Alloys
Authors: Wang Yao , Jiang Qing Wei , Wu Ying , Li Xiao Wu
Published: December 2010

The individual or joint effects of annealing and equal channel angular pressing (ECAP) treatments on the high-temperature compressive deformation and damage behavior of cast LY12 Al alloys were studied. The compressive deformation behavior and surface deformation and damage characteristics of differently treated LY12 Al alloy samples were examined at temperatures ranging from 25°C to 400°C. It is found that the LY12 Al alloy exhibits different compressive mechanical behavior depending on different treatments, and the compressive deformation and damage characteristics of LY12 Al alloys with different microstructural states are closely related with the testing temperature. As compared to other samples (e.g. as-cast, annealed, as-cast+2ECAPed), the sample annealed at 450°C for 3h followed by ECAPed for 2 passages (i.e. annealed+2ECAPed) shows a better high-temperature deformation stability.
Ultrafine-Grained Steel Produced by Warm Rolling and Annealing of Lath Martensite
Authors: Zhao Xin , Yang Xiao Ling
Published: December 2010

Steel plates with lath martensite microstructure were rolled up to 68% reduction at 673 K and then annealed at 473-973 K. The microstructure evolution was studied by using an optical microscope and a transmission electron microscopy. And the properties were investigated by using tensile tests and hardness tests. Results show that ultrafine grains + nano-carbides are obtained in the steel plates. The specimen annealed at 823 K has a good combination of strength and ductility. The tensile strength and total elongation are 1028 MPa and 7.2%, respectively. And the hardness is 338 Hv.
Nano-Refinement, Nano-Consolidation: Different Fabrication Routes of Nano-Crystalline Aluminium Alloys
Authors: Lewandowska Małgorzata , Dybiec Henryk , Kulczyk Mariusz , Latuch Jerzy , Kurzydlowski Krzysztof J.
Published: December 2010

The aim of the present work was to compare microstructures and mechanical properties of nano-Al alloys fabricated by two different methods: (i) SPD induced grain refinement, (ii) plastic consolidation of nano-powders or nano-crystalline ribbons. SPD grain refinement has been implemented by hydrostatic extrusion, HE. The ribbons were rapidly solidified using a melt spinning methods. Plastic consolidation of powder and ribbons was conducted by warm extrusion. The results of the studies show that by applying various fabrication routes for a given chemical composition, diverse nano-structures can be obtained, which differ in terms of grain size and shape, grain boundary character and dislocation density. As a result, the alloys also differ significantly in the mechanical properties. The findings are discussed in terms of the possibilities for optimizing properties of the bulk-nano-metals.
Near-Threshold Fatigue Crack Propagation in an ECAP-Processed Ultrafine-Grained Aluminium Alloy
Authors: Hockauf Kristin , Halle T. , Hockauf Matthias , Wagner Martin F.X. , Lampke Thomas
Published: December 2010

In the present work, the near-threshold fatigue crack propagation (FCP) at different load ratios is studied for an aluminium alloy processed by equal-channel angular pressing (ECAP). The conditions under investigation represent different stages of microstructural refinement as well as a ductility-optimized condition with superior crack growth properties, obtained by a combination of ECAP and aging. The results show a strong dependency of the threshold and its load ratio sensitivity on the grain size and grain size distribution. These observations can be rationalized on the basis of crack path tortuosity and the contribution of (roughness-induced) crack closure. Moreover, the experimental data is evaluated using the two-parametric concept of Vasudevan and Sadananda, which employs two necessary minimum conditions for crack growth, namely a critical cyclic K*th, and a critical maximum stress intensity K*max. The application of this concept shows a strong interaction of both parameters for all ECAP-processed conditions, where the ductility-optimized condition reveals superior FCP properties compared to the “as-processed” conditions.
Effect of ECAP on the Microstructure and Mechanical Properties of 17-4PH Stainless Steel
Authors: Yang Gang , Yin Feng Shi
Published: December 2010

Experiments were conducted to evaluate the influence of equal-channel angular pressing (ECAP) on the microstructure and mechanical properties of 17-4PH steel. The 17-4PH steel was solution-treated at 1040°C for 1h followed by oil cooling before ECAP process. Both the as solution-treated and ECAPed specimens were tempered at 460°C and 610°C for 2h, respectively. Tensile, impact and hardness properties as well as the microstructure and fracture mode were systematically studied. The results show that both the tensile strength and hardness are increased by ECAP process, the elongation is deceased but the Charpy V-notch energy absorption is increased by ECAP process when the tempering treatment is at a low temperature of 460°C, while the result is just reverse when the tempering temperature is 610°C. SEM observation reveals that the ECAP process promotes the precipitation of M23C6-type carbide obviously. The relations among ECAP process, microstructure, mechanical properties and fracture modes are discussed.
Precipitation Effect on Work Hardening Behavior of ECAP-Deformed Al-4%Cu Alloy
Authors: Prados Erika Fernanda , Sordi Vitor Luiz , Ferrante Maurizio
Published: December 2010

It is well known that severe plastic deformation techniques, while giving substantial strength benefits, produce low ductility material. The aim of the present work is to analyze whether second phase precipitates obtained by post-deformation heat treatment, have a positive effect on the W-H behavior. On this sense, the typical precipitation hardening Al-4%Cu alloy is subjected to one and four ECAP passes, followed by low temperature precipitation heat treatment. The W-H behavior and the mechanical stability were determined for two levels of ECAP - deformation, different precipitates average size and distribution, and presence/absence of solute in solid solution. It was concluded that Al2Cu precipitates increased both W-H rate and uniform elongation of the alloy and the best strength - ductility combination was obtained by a post-deformation, 100oC precipitation heat treatment of a sample which was ECAP-deformed in the solid solution condition.
Effect of Equal-Channel Angular Pressing on the Creep Resistance of Precipitation-Strengthened Alloys
Authors: Sklenička Václav , Král Petr , Dvořák Jiří , Kvapilová Marie , Kawasaki Megumi , Langdon Terence G.
Published: December 2010

Despite intensive research efforts in precipitation-strengthened alloys processed by equal-channel angular pressing (ECAP), so far only a few investigations have been conducted on their creep behaviour and the results from these studies are controversial. This paper examines these differences and evaluates some factors influencing the creep resistance of the binary Al-0.2%Sc and Cu-0.2% Zr alloys processed by ECAP.
Ultrafine Structure Formation in Aluminium Alloy Processed by HPT and the Mechanical Properties Response
Authors: Zrník Jozef , Pippan Reinhard , Scheriau Stephan , Fujda Martin
Published: December 2010

In this study ultrafine grain structure evolution during high pressure torsion (HPT) of commercial aluminium alloy AA6082 at increased temperature is presented. Two different initial structural states of the alloy were prepared by thermal treatment. The progress in structure refinement in dependence on the shear strain level strain was investigated by TEM of thin foils. The impact of different amount of strain (εef) introduced was analyzed with respect to the effect of increased temperature. The microhardness results measured across the deformed discs pointed out that some data scattering. The results of microstructure analyses showed that ultrafine grain (ufg) structure was already formed in deformed disc upon the first turn, regardless the initial structure of alloy, resulting from prior thermal treatment. The observed heterogeneity in ufg structure formation across the deformed disc was observed, supporting microhardness results scattering. By increasing the strain level (number of turns N -2,4,6), more effectively homogenized ufg structure was observed across the deformed discs. The effect of increased deformation temperature became evident and dynamic recrystalization modified locally ufg structure. The retardation of new grains growth and higher thermal stability of ufg structure was observed, when two steps thermal treatment of alloy (quenching and ageing) was executed prior deformation. Strength measurements results yielded from tensile tests showed that the effect of structure strengthening was degraded by local recrystallization. The results of torque measurement versus the time showed that the torque required to deform the sample was increasing until the first turn and then kept stable or even decreased.
Production a High-Strength and High-Conductivity Copper Wire by Using Equal-Channel Angular Hydroextrusion Method
Authors: Davydenko Oleksandr , Spuskanyuk Victor , Varyukhin Viktor
Published: December 2010

A new approach is proposed to control the processes of billets plastic deformation during metal treatment by the methods of severe plastic deformation (SPD). High strength and plasticity have been attained for the processed copper billets after multiple repetitions of equal channel angular hydroextrusion (ECAH) and direct hydroextrusion (HE) techniques and with ECAH and HE implementation in the fractional mode. The combined SPD treatment including ECAH, HE and drawing (D) provided for fire refined tough pitch copper (Cu-FRTP) the ultimate tensile strength =686 MPa, the elongation to failure =2% and the electrical conductivity (EC) at a level of 86.4% IACS and for oxidant free copper (Cu-OF) =576 MPa, =1.9%, EC=96.7% IACS in the 0.5 mm diameter wire. Such treatment is efficient due to the alternative schemes of deformation, the fractional mode and the optimum degrees of plastic deformation and periodic creation of favorable conditions for relaxation and dynamic recrystallization processes in the material.
Structure Evolution and Deformation Mechanisms in Ultrafine-Grained Aluminum under Tension at Room Temperature
Authors: Ivanov Konstantin V. , Naydenkin Evgeny V.
Published: December 2010

Deformation mechanisms occurring by tension of ultrafine-grained aluminum processed by equal-channel angular pressing at room temperature are investigated using comparative study of the microstructure before and after tensile testing as well as deformation relief on the pre-polished surface of the sample tested. Deformation behavior and structure evolution during tension suggest development of grain boundary sliding in addition to intragrain dislocation slip. Contribution grain boundary sliding to the overall deformation calculated using the magnitude of shift of grains relative to each other is found to be ~40%.
Microstructure and Strength of Welded Joints of Steel after Equal-Channel Angular Pressing
Authors: Ivanov Afanasiy M. , Soshnikova Evgeniya P. , Argunova Anastasiya A. , Gunderov Dmitriy , Petrova Nurguyana D.
Published: December 2010

The possibility of equal-channel angular pressing (ECAP) of steel billets with welded seams, the study of the microstructure and determine the characteristics of the weld strength and ductility is investigated. Two cylindrical work pieces (20 mm) of steel St3sp obtained by welding were subjected to ECAP. Investigation of the weld microstructure was carried out for three zones: base metal, weld metal and heat affected zone. Determining results the strength and ductility characteristics of the weld in the initial state and after ECAP are presented.
Structure and Hardness of Cryorolled and Heat-Treated 2xxx Aluminum Alloy
Authors: Krymskiy S.V. , Avtokratova Elena , Markushev M.V. , Murashkin Maxim Yu. , Sitdikov O.S.
Published: December 2010

The effects of severe plastic deformation (SPD) by isothermal rolling at the temperature of liquid nitrogen combined with prior- and post-SPD heat treatment, on microstructure and hardness of Al-4.4%Cu-1.4%Mg-0.7%Mn (D16) alloy were investigated. It was found no nanostructuring even after straining to 75%. Сryodeformation leads to microshear banding and processing the high-density dislocation substructures with a cell size of ~ 100-200 nm. Such a structure remains almost stable under 1 hr annealing up to 200oC and with further temperature increase initially transforms to bimodal with a small fraction of nanograins and then to uniform coarse grained one. It is found the change in the alloy post–SPD aging response leading to more active decomposition of the preliminary supersaturated aluminum solid solution, and to the alloy extra hardening under aging with shorter times and at lower temperatures compared to T6 temper.
Effect of ECAP on Mechanical Properties of an AA2014 Alloy
Authors: Kaibyshev Rustam , Mogucheva Anna
Published: December 2010

An AA2014 alloy was subjected to equal channel angular pressing in quenched condition up to fixed true strains of 1, 2 at a temperature of 170oC followed by artificial aging at the similar temperature. ECAP provides accumulation of a high dislocation density after a true strain of 1 and the formation of subgrain structure and separate chains of nanoscale grains after a true strain of 2. Yield stress (460 MPa) of the AA2014 alloy after 1 and 2 passes was the same. In contrast, increasing strain from 1 to 2 leads to three-fold increase in ductility.
Transient Yielding during Compression Tests on ECAP’ed AA1050 Aluminium
Authors: Verlinden Bert , Chen En Ze , Duchêne Laurent , Habraken Anne Marie
Published: December 2010

In most papers dealing with tension and/or compression tests, the conventional yield stress is determined either by an offset method (usually 0.2% strain) or by back extrapolation from the stress-strain curve. In our experiments on ECAP’ed Aluminium a transient hardening saturation (THS) is always observed during the compression tests, but not during the tensile tests. This THS occurs at a significantly lower stress than the conventional yield stress. The aim of the present paper is to determine which the “real” start of yielding is. Two different experimental approaches have been adopted, confirming that the THS stage is exactly the yielding stage. This is not unimportant because it increases the tension-compression asymmetry and hence the back-stress and kinematic hardening. The reason for this different behaviour between tension and compression can be ascribed to a different change in strain path with respect to the ECAP deformation.
Influence of Thermal Cycling on Dilatation and Electrical Resistance of Ti - 49.8 at. %Ni Alloy after Hot Rolling
Authors: Babicheva R.I. , Sharipov I.Z. , Mulyukov K.J.
Published: December 2010

The effect of thermal cycling of the Ti - 49.8 at. % Ni alloy deformed by rolling at 500 оС on dilatation of the material was investigated. It was shown that R → B2 and B19' → B2 phase transformations take place during heating due to retaining of R-phase at the lowest temperature of cycling. The evolution and subsequent stabilization of two-way shape memory effect (TWSME) upon thermal cycling are caused by decreasing of the residual B19'- martensitic phase formed during rolling. It was revealed that recoverable strain of the alloy doesn’t exceed 0.8 % even after forty cycles.
On Gradient Nanomechanics: Plastic Flow in Nanopolycrystals
Authors: Zhang Xu , Romanov A.E. , Aifantis Elias C.
Published: December 2010

Gradient nanomechanics is a generalized continuum mechanics framework accounting for “bulk-surface” interactions in the form of gradient terms that enter in the evolution equations of the relevant constitutive variables and/or in the governing field equations. This approach is discussed in the paper by developing appropriate differential equations for the plastic strain and/or the structural defects that bring this about. The effectiveness of the approach is illustrated by considering size-dependent stress-strain curves for nanopolycrystals with varying grain size.
Characterization of AM60 Magnesium Alloy Prepared by Rapid Solidification and Plastic Consolidation Technique
Authors: Tokarski Tomasz
Published: December 2010

Magnesium and its alloys are attractive candidates for automotive and aerospace applications due to their relatively high strength and low density. However, their low ductility determined by hcp structure of material results in limitation of plastic deformation processing. In order to improve ductility as well as mechanical properties, structure refinement processes can be used. It is well known that effective refining of the material structure can be achieved by increasing the cooling rate during casting procedures, hence rapid solidification process (RSP) has been experimented for the fabrication of magnesium alloys. The present paper reports an experimental investigation on the influence of rapid solidification on the mechanical properties of AM60 magnesium alloy. In order to obtain RS material melt spinning process was applied in protective atmosphere, resulting in formation of RS ribbons. Following consolidation of the RS material is necessary to obtain bulk material with high mechanical properties, as so hot extrusion process was applied. It was noticed that application of plastic consolidation by hot extrusion is the most effective process to achieve full densification of material. For comparison purposes, the conventionally cast and hot extruded AM60 alloy was studied as well. The purpose of the present study was to investigate in detail the effect of rapid solidification and extrusion temperature on the structure and mechanical properties of the materials.
Numerical Analysis of the Polishing Process of Inner Tube Wall Using Micron-Size Particles in Magnetic Fluids
Authors: Ido Yasushi , Yamaguchi Takaya , Nishida Hitoshi
Published: December 2010

Distribution and behaviour of micron-size magnetic particles and nonmagnetic particles in magnetic fluids in the polishing process of inner wall of small tube is investigated numerically by using the particle method based on the simplified Stokes dynamics. In this study, it is shown that chain-like clusters of both magnetic particles and those of nonmagnetic abrasive particles are formed between the two magnetic poles. The clusters are strongly held during the polishing process. The clusters of the nonmagnetic abrasive particles are surrounding the clusters of magnetic particles and they are combined with each other.
New Signal Processing Method for Electromagnetic Inspection Using Multidirectional Magnetizing Type Sensor
Authors: Suzuma Toshiyuki
Published: December 2010

New signal processing method for Electromagnetic Inspection using multidirectional magnetizing type sensor has been developed to detect linear-shaped defects such as cracks in every direction in test objects. In this method, the Amplitude-Modulated alternating currents, whose waveforms are the product of two sinusoidal waves of different frequencies, are used to produce a rotating magnetic field in test objects. The signal caused by a lift off variation of the sensor, which is not avoidable by conventional multidirectional magnetizing method, is reduced by this method. The effect is investigated by a test using 0.25% carbon steel sheet. It is also investigated that the inclined angles of defects are obtained by the phase information of the signal in a phasor diagram.
Adaptive Scanning Algorithm Based on Neural Network Prediction of Eddy Current Testing Signals
Authors: Lopato Przemysław , Chady Tomasz , Todaka Takashi
Published: December 2010

In this paper an adaptive scanning algorithm for Eddy Current Non-Destructive Testing (EC NDT) is proposed. It is based on neural prediction of EC signals. A set of experiments were carried out in order to prove usability of the method (verification by numerical analysis and measurements of INCONEL 600 1.25 mm thin plates). Proposed algorithm may be used as a part of intelligent NDT system.
A Magnetic Microsensor with Temperature Compensation Based on Optical Mechatronic Technology
Authors: Lai Chi Chih , Chang I Nan , Chang Hsing Cheng , Hwang Chang Chou , Liu Wen Fung , Ma Chin Hsiang , Chen Ya Hui
Published: December 2010

An optical mechatronic magnetic microsensor with temperature compensation based on fiber Bragg grating (FBG) and microelectromechanical system (MEMS) technologies is demonstrated. Parallel nickel-electroplated cantilever beams are fabricated as an attractive bending mechanism for pushing the optical fiber. Related stress induced cantilever bend caused by magnetic force driving reflective wavelength shift that exactly corresponds with photo-elastic coupling effect to characterize microsensors. Two different cycles of gratings in the same fiber have fabricated to perform the function of magnetic sensing and temperature compensation for reducing temperature-induced bias in magnetic measurement automatically. The sensitivity of 2.238 T/nm with null temperature response has obtained which excited by Nd-Fe-B magnets with residual magnetic strength up to 1.26 Tesla.
Integral-FEM Simulation and Independent Component Analysis for Multiple Defect Separation from Pulse Eddy Currents Signals
Authors: Preda Gabriel , Hantila Ioan Florea
Published: December 2010

Pulse eddy currents simulated using an integral formulation and Independent Component Analysis (ICA) for signal separation are used for detection of multiple defects in thick conductive plates. Numerical results for the eddy-currents signals, and signal separation using ICA, are shown.
Characteristics of Hydrodynamic Pressure of a Magnetic Fluid in a Tuned Magnetic Fluid Damper
Authors: Ohno Ken Ichi , Sawada Tatsuo
Published: December 2010

A tuned magnetic fluid damper (TMFD) is a semi-active dynamic absorber using a magnetic fluid as a damping mass. A characteristic of the TMFD is to change a natural frequency of a sloshing. When a magnetic field is applied to a container filled with a magnetic fluid from below, the natural sloshing frequency increases and a range of a damping frequency is spread. In this paper, pressure measurements were used to control the appropriate magnetic field.
High Pressure Synthesized Magnesium Diboride- and Dodecaboride-Based Superconductors: Structure and Properties
Authors: Prikhna Tatiana , Gawalek Wolfgang , Savchuk Yaroslav , Mamalis Athanasios G. , Tkach Vasiliy , Weber Harold , Habisreuther Tobias , Eisterer Michael , Karau Fridrikh , Wendt Michael , Sergienko Nina , Moshchil Viktor , Kozyrev Artem , Nagorny Peter , Schmidt Christa , Melnikov Vladimir S. , Dellith Jan , Litzkendorf Doris , Noudem Jacques G. , Chaud Xavier , Sverdun Vladimir , Shapovalov Andrey , Starostina Alexandra
Published: December 2010

The critical current density, jc, of high-pressure synthesized MgB2-based balk materials correlates with the amount and distribution of higher borides (MgB12) and Mg-B-O inclusions, which in tern correlates with the synthesis temperature and presence of additions (Ti, Ta, SiC). High-pressure-synthesized materials with near MgB12 composition of matrix exhibited superconducting transition temperature, Tc, of about 37 K, rather high jc (5∙105 and 103 A/cm2 in 0 T and 3.5 T, respectively, at 20 K) and doubled matrix microhardness: 25±1.1 GPa at 4.9 N –load as compared to materials with MgB2).
Surface Responses of Magnetic Fluid Adsorbed to Permanent Magnet Subject to Vertical Vibration
Authors: Sudo Seiichi , Kurosu Yuichi , Asano Daisaku
Published: December 2010

The surface responses of magnetic fluid adsorbed to a ferrite permanent magnet subject to vertical vibration were studied experimentally. It was found that pulsating capillary jets of magnetic fluid were produced at a certain excitation frequency. Large-amplitude azimuthal surface motions occurred when the fluid responded as a one-half subharmonic of the excitation.
Design Comparison of Fractional-Slot IPM Machine Types for an Electric Power Steering Application
Authors: Hwang Chang Chou , Chang Hsing Cheng , Ho Ming Te , Liu Cheng Tsung
Published: December 2010

This paper deals with the design comparison of interior permanent magnet (IPM) motors with fractional-slot winding configurations for an electric power steering (EPS) application. By making comparisons of these configurations based on cogging torque, torque ripple, average torque, and efficiency, an IPM rotor configuration has been chosen for use as a prototype motor. The Taguchi parameter method coupled with the finite element analysis (FEA) is employed to achieve the desired performance requirements within a reasonable geometry. To assess the rated current and thermal behavior of the motor, the lumped circuit models are conducted.
Simple-Box-9 Coil System: A Novel Approach to Design of a Square Coil System for Producing Uniform Magnetic Fields
Authors: Tashiro Kunihisa , Matsuoka Akihito , Wakiwaka Hiroyuki
Published: December 2010

This paper presents a novel approach for the design of square coil system, through considerations of a conventional square coil system. This simple approach allows us to design a coil system which contains a greater number of coils. From this design method, we introduce a new structure system of same-sized square coils, Simple-Box-9. The constant coil spacing is a fourth-part of the side length of the coil, and the number of windings is 2/1/1/1/1/1/1/1/2. From numerical calculations and experiments, it is shown that Simple-Box-9 can achieve the best uniformity compared with conventional square coil systems.
Impact of the Magnetic Flux Penetrating Vortex Core on the Critical Current of the HTc Superconductors
Authors: Sosnowski Jacek
Published: December 2010

New model of the capturing vortices in the HTc superconductors is presented, describing their electromagnetic properties, such as the critical current of these materials. Critical current of the superconductors, such as HTc tapes is dependent on the magnitude of the interaction magnetic vortices with pinning centers. This is in fact quantum effect since the magnetic flux in vortices is quantized. Capturing the vortices on the normal state nano-sized inclusions should lead to the modification of the flux distribution in the vortex core depending on the vortex position in the respect to the pinning center edge. These effects are considered in the paper and their influence on the critical current of the HTc materials, basing on the new model of the pinning interaction.
Optimal Solutions for Uniform Heating of a Non-Ferrous Bar by Electromagnetic Induction, Using Numerical Modeling
Authors: Leuca Teodor , Mich-Vancea Claudiu , Nagy Stefan
Published: December 2010

The paper intends to present the numerical modelling of the electromagnetic phenomena coupled with the thermal ones when processing the semi-finished products made up of non-ferrous alloy, through electromagnetic induction with the purpose of obtaining a homogenous heating of the pieces in the shortest time. The purpose of the numerical modelling in this paper is to check cheap solutions to homogenize the intensity of the magnetic field according to the geometry of the inductor, by using a magnetic field intensifier or if it is possible to use the motion of the pieces inside the inductor.
Identification of Conductivity Distribution Using Eddy Current Tomography System and Artificial Neural Networks
Authors: Chady Tomasz , Spychalski Ireneusz , Todaka Takashi
Published: December 2010

In certain applications (security, biomedical, food and wood testing etc.) it is necessary to detect and identify position of small metal particles with high precision. This paper presents an eddy current system designated for evaluation of conductivity distribution. The system was modeled using the finite element method as well as it was constructed and the measurements were carried out. Using these results a data base of the signals achieved for various configurations of the test objects were created. The data base was utilized to solve the identification problem. Artificial neural networks were utilized as the inverse models in order to reconstruct two-dimensional distribution of conductivity. Selected results achieved for simulated signals were presented.
Current-Phase Relation of YBa2Cu3O7-X/Nb Unconventional Superconductor Junctions
Authors: Chesca Boris , Smilde Henk Jan , Hilgenkamp Hans
Published: December 2010

The knowledge of the current-phase relation (CPR) in superconducting junctions is essential in many applications like low-dissipative superconducting electronics or superconducting qubits for quantum computation. Theory predicts that unconventional superconductivity induces a significant second harmonic J2 in the CPR. Consequently, anomalies such as half-integer Shapiro steps should be observed in the microwave assisted current-voltage characteristics of the junctions. We performed electric transport measurements in YBa2Cu3O7-x/Nb unconventional superconductor junctions for 72 different tunneling directions in the ab plane and found no trace of such anomalies. This suggest that J2 is insignificantly small so that YBa2Cu3O7-x/Nb junctions have a purely sinusoidal CPR.