Started in 1985 Semimonthly
ISSN 1005-0302
CN 21-1315/TG
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The journal has been awarded the excellent periodical in China, and its articles are covered by SCI, EI, CA, SA, JST, RJ, CSA, MA, EMA, AIA etc., PASCAL web. ISI web of Science,SCOPUS.

Current Issue
 28 December 2004, Volume 20 Issue Supl. Previous Issue    Next Issue
Research Articles
 Select Commercial Purity Aluminum with a BimodalGrain Size Distribution: Mechanical Properties, Deformation and Fracture Mechanisms S.Billard, E.Meslin, G.F.Dirras, J.P.Fondère, B.Bacroix J. Mater. Sci. Technol., 2004, 20 (Supl.): 1-5.  Abstract   HTML   PDF (460KB) Commercial purity Al has been processed by hot isostatic pressing consolidation of nanopowders. The resulting bulk material contained a small fraction of microcrystalline grains (>300 nm) embedded in a matrix of ultrafine grains (150 nm). The mechanical properties under compressive tests at various temperatures and at a strain rate of 2×10－4 s－1 have been investigated. At room temperature a brief hardening was observed followed by a stagnation of the flow stress up to failure. From 150 to 200℃ softening occurred after a short hardening stage. A change in the behavior showed up at 300℃: a quasi perfect plasticity was observed subsequently to a yield point. The major deformation mechanisms include dynamic recovery, grain fragmentation and sliding. Besides, when tested up to rupture at elevated temperature filament formation where observed at the fracture surface. The formation mechanism of the filaments is possibly linked to the presence of a viscous-like phase at grain boundaries.
 Select Micromechanical Estimation of the Shear Modulus of a Composite Consisting of Anisotropic Phases H.Le Huang, Q. -C.He J. Mater. Sci. Technol., 2004, 20 (Supl.): 6-11.  Abstract   HTML   PDF (317KB) This work is concerned with a composite whose phases exhibit spherical transverse isotropy. A spherulitic polymer can be suitably modeled as such a composite. The problem of a hollow sphere consisting of a material of spherical transverse isotropy and undergoing shear strain or stress is first solved. The generalized self-consistent scheme is then applied to estimating the effective shear modulus of the composite as the positive root of a quadratic equation.
 Select Combined Experimental and Finite Element Studies of Anisotropic Friction S.Rhaiem, M.Dammak, A.Shirazi-Adl, W.Mesfar, A.Maalej J. Mater. Sci. Technol., 2004, 20 (Supl.): 11-14.  Abstract   HTML   PDF (242KB) Anisotropic friction likely exists in human natural/artificial joints as well as various engineering systems with articulating bodies. In this study, a new experimental apparatus is designed and fabricated to measure load-displacement friction properties at the metal-polymer interface. Anisotropic friction properties at the polymer-metal interface are measured under tangential loads applied at different directions. Two series of polymer specimens with different surface roughness are considered. Metal specimens with similar surface roughness are used in this study. The measured interface tangential load-displacements are highly nonlinear exhibiting relatively large displacements prior to ultimate shear resistance forces. This is in contrast to conventional Coulomb friction curves in which no relative displacements occur before the maximum resistance forces are reached. The interface ultimate resistant force varies with the direction of loading, suggesting an elliptic failure criterion and demonstrating the anisotropy of the interface friction. For example, the mean friction coefficient along two interface perpendicular directions is measured to be about 0.12 and 0.19. These experimental results are incorporated into our existing numerical models of interfaces with nonlinear isotropic and anisotropic friction properties. The good agreement between experimental and finite element model results confirms the nonlinear, nonsymmetric, coupled constitutive relations developed to represent anisotropic interface friction properties. In this study, we have observed that the friction coefficient could vary significantly depending on the direction of loading. The current work also verifies the accuracy of developed finite element model to predict the response of contacting bodies with anisotropic friction.
 Select Damage Mechanisms at a Microscopic Scale of PM Ti-6Al-4V at 20 K S.Di Iorio, L.Briottet, C.Cayron, E.F.Rauch, D.Guichard J. Mater. Sci. Technol., 2004, 20 (Supl.): 15-18.  Abstract   HTML   PDF (448KB) The microscopic damage mechanisms at cryogenic temperature of an extra low interstitial Ti-6Al-4V obtained by powder metallurgy (PM) are investigated. Through SEM observations and EBSD mapping, it is attempted to identify the microstructural features that control the damage. Damage nucleation as well as texture evolution with strain are particularly analyzed. It is shown that both features are closely related to twinning.
 Select Hot Ductility Study of Continuous Casting Steels T.Revaux, J.D.Guérin, J.P.Bricout J. Mater. Sci. Technol., 2004, 20 (Supl.): 19-22.  Abstract   HTML   PDF (535KB) New generation of steel casting processes allow to increase the production rate but they cause some imperfections instance. The main detrimental defects of metallurgical products generally occur during their solidification and cooling. The thermomechanical loadings undergone by the steel form the liquid state must be consequently considered with care. In this context, it is necessary to design some thermomechanical tests that dedicate to study the defectology products and the hot brittleness of steels. Hot mechanical tests use some notched axisymetric specimens and are able to reproduce the real material history. The analyses mainly allow to generate objectives thermomechanical stresses of the strand casting product and know some sensibility parameters on the failure instance. Contributions are relative to the hot ductility and micro or macrosegregation bonds and effects of strain during solidification on the cracks instances. The present results have been obtained from two types of procedure: tensile strain and contraction tests. These procedures are used to determine behaviour of continuous casting steels and cooling rate effects. Contributions are mainly relative to the hot ductility.
 Select On the Crack Initiation and Growth in a Strongly Dynamic Strain Aging Aluminum Alloy Sheet W.Tong, N.Zhang J. Mater. Sci. Technol., 2004, 20 (Supl.): 23-26.  Abstract   HTML   PDF (414KB) Serrated plastic flows in an Al sheet (AA5182-H19) were first characterized temporally and spatially under quasistatic uniaxial tension. Discrete types B and C serrations or Portevin Le-Chatelier (PLC) bands started to appear at a plastic strain of 2.54% with an average stress drop of 2.5 MPa and an average time interval of 7.75 s between serrations. The width of the individual PLC bands was about twice of the thickness of the sheet (0.235 mm) and the plastic strain inside the bands was as high as 2%. V-notched tear test coupons made of the same Al alloy were then stretched under both continuous monotonic and periodic interrupted loading conditions and their crack initiation and growth processes were monitored by direct digital imaging. The crack tip opening angle (CTOA) and the crack tip opening displacement (CTOD) were measured to be about 2.5～3℃ and 0.07～0.1 mm, respectively. While no major load serrations were observed before crack initiation at the notch tip, discontinuous or intermittent crack advances or crack jumps were unambiguously detected in the crack growth stage. The unstable crack propagation in the AA5182-H19 sheet seems to be related closely with its strong dynamic strain aging behavior exhibited under quasistatic loading conditions at the ambient temperature.
 Select Multiscale Observation of Polymer Materials in Order to Explain Mechanical Behaviour and Damage Mechanism by X-ray Computed Tomography E.Bayraktar, F.Montembault, C.Bathias J. Mater. Sci. Technol., 2004, 20 (Supl.): 27-31.  Abstract   HTML   PDF (802KB) The study of microstructural network and damage mechanism of polymer and rubber, although deceptively simple, involves a complex interplay between material properties and service conditions. So, the study of the texture, deformation and the failure of rubber specimens are of considerable practical interest. In fact, the occurrence of defects such as the initiation and the growth of cavitations in rubber specimens in working conditions is an important problem. These deal with the improvement of microstructure (for delaying instability) in order to obtain a higher service capacity. The scope of the present paper is, therefore, to evaluate principal mechanisms, in-situ observation of damage at mesoscopic, microscopic and macroscopic levels by using X-ray computed tomography (CT) installed in the ITMA research centre for confirming the behaviour of natural rubber (NR) and styrene butyl rubber (SBR) specimens used in automotive and aeronautical fields.
 Select Stress Distribution and Cleavage Analysis in a 16MnNiMo5 Bainitic Steel X-ray Diffraction and Multiscale Polycrystalline Modelling Raphaë, l Pesci, Karim Inal, Renaud Masson J. Mater. Sci. Technol., 2004, 20 (Supl.): 32-34.  Abstract   HTML   PDF (408KB) Many tensile tests have been realized on the 16MnNiMo5 bainitic pressure vessel steel at low temperatures [-196℃,-60℃. The damaging processes (ductile/fragile) are observed with a scanning electron microscope (SEM), while X-ray diffraction (XRD) is used to determine the internal/residual stresses within the ferritic phase during loading (in-situ) and after unloading: stress states are lower in ferrite than in the bulk material due to cementite particles, the difference never exceeding 150 MPa. A polycrystalline modelling with a two-level homogenisation is also developed concurrently with the experimental characterization. It correctly reproduces the stress distribution in each phase, the intergranular strain heterogeneity as well as the macroscopic fracture stress and strain in relation to temperature, considering a constant number of grains (7%) reaching an experimentally identified crystallographic criterion of cleavage.
 Select A New Approach to Determine the Contact Radius-Depth Curve from an Indentation Test in Elastic-Plastic and Fully Plastic Regimes O.Bartier, X.Hernot, Y.Bekouche, G.Mauvoisin, R.El Abdi J. Mater. Sci. Technol., 2004, 20 (Supl.): 38-40.  Abstract   HTML   PDF (264KB) Instrumented indentation experiments, where load and depth of penetration are measured continuously, enable an evaluation of mechanical properties such as Young's modulus, hardening exponent and yield stress. This assessment requires a precise knowledge of the true contact area between the indenter and the indented material, which depends on piling-up and sinking-in at the contact boundary. The aim of this work is to propose a new relationship between the penetration depth of a spherical indenter and the contact radius, which is valid for most metals in elastic-plastic and fully plastic regimes. Numerical simulations results of the indentation of an elastic-plastic half-space by a frictionless rigid paraboloìd of revolution show that the contact radius-indentation depth evolution can be represented by a power law. This law depends on the Young's modulus, the hardening exponent and the yield stress of the indented material. In order to use the proposed formulation for experimental spherical indentations, the model is adapted in the case of a rigid spherical indenter.
 Select Evaluation of Microstructure and Mechanical Properties in Case Layer of Carburizing-quenched SCr420 Steel by Numerical Simulation and Experimental Methods Ming QIN, Dong-Ying Ju, Yan ZHANG, Pei BIAN J. Mater. Sci. Technol., 2004, 20 (Supl.): 41-44.  Abstract   HTML   PDF (347KB) The previous work has indicated that the carburizing-quenching process is often accompanied by the decarburization in the surficial layer of mechanical parts. A numerical model based on “metallo-thermo-mechanics” was used to estimate the microstructure and residual stresses in the case layer of a carburizing-quenched SCr420 steel. In order to verify above model, the experimental methods, such as XRD, color metallography, microhardness indentation, and EPMA, are also used to analyze the correlative parameters. The decarburization in the carburizing-quenched SCr420 steel was observed, and the simulation results are a little different from the experimental results. According to the results, the factors of reducing the accuracy of the numerical simulation method have been discussed.
 Select Numerical Simulation for Dendrite Growth of Binary Alloy with Phase-Field Method Hua HOU, Dong-Ying Ju, Yuhong ZHAO, Jun CHENG J. Mater. Sci. Technol., 2004, 20 (Supl.): 45-48.  Abstract   HTML   PDF (400KB) Two-dimensional numerical simulation for the dendrite growth of binary alloy during solidification is carried out by a phase field method. In the model equations, phase field, temperature and solute redistribution are all involved. The equations are solved using the finite difference method (FDM) with two different space steps of phase field and temperature field. In calculation, the thermal noise is introduced to generate the side branches; the dependence of dendrite growth on the space step was also investigated. It is shown that thermal noise can trigger the growth of side-branches, however it has no influence on the stable behavior of the dendrite tip; the feature of dendrite growth is reasonable with δ Δx≤0.6W0, Δx is the space step and W0 is the thickness of interface.
 Select Evaluation and Improvement of the Bending Process of Connector Elements by Finite Element Simulations C.Poizat, W.Schmitt, A.Krasowsky, F.Andrieux, E.Haas, R.Mö J. Mater. Sci. Technol., 2004, 20 (Supl.): 49-51.  Abstract   HTML   PDF (350KB) Simulation results obtained in the development of a reliable bending process of a connector element are presented. For an accurate modelling of springback, the material hardening behaviour is characterized through tension-compression tests. Based on these data and using a Chaboche-type material model, finite-element (FE) analyses are carried out to identify the key material and process parameters and their influences on the final product geometry.
 Select Metal Matrix Composite Processing: Experimental and Numerical Study of Infiltration of Fibrous Preforms by a Binary Alloy A.Cantarel, E.Lacoste, O.Mantaux, E.Arquis, M.Danis J. Mater. Sci. Technol., 2004, 20 (Supl.): 52-54.  Abstract   HTML   PDF (203KB) Injection of liquid alloy through a fibrous preform located in an initially preheated mould is a classical method used to process metal matrix composites (MMCs). In order to reduce the chemical reactions between the fibres and the metal matrix, the fibrous reinforcement and the mould are commonly preheated up to initial temperatures much lower than the metal solidification temperature. Therefore, metal solidification instantaneously occurs on fibre contact during composites infiltration. Unlike what happens when infiltrating a pure metal, temperature and composition are able to vary within the matrix; these heterogeneities induce macrosegregation within composites...
 Select A New Multilayered Nanostructured Composite Material Produced by Assembling SMA-Treated Thin Plates T.Rol, M.Ya, D.Retraint, K.Lu, J.Lu J. Mater. Sci. Technol., 2004, 20 (Supl.): 55-58.  Abstract   HTML   PDF (464KB) Surface mechanical attrition treatment (SMAT) can produce a nanometer-grained surface layer without porosity and contamination on a bulk stainless steel. The nanostructured layer has high strength that contributes to an overall increase in the mechanical properties of the nanostructured sample. In this study, a new nanostructured composite was developed by assembling three SMA-treated thin plates. An FEM model based on nanoindentation data was established to simulate the stress-strain relationship. The simulation and the experimental tension curve correspond well. Moiré interferometry was used to observe the tensile behavior of the new composite in real time. A tension test conducted on a specimen consisting of three 500~μm thick SMA-treated sheets showed that the yield stress is much higher than that of a bulk-treated sample of the same total thickness. Based on these results, the new multilayer composite would seem to be a promising structural material due to its high strength/weight ratio.
 Select Preparation and Characterization of Rutile-TiO2 Nanorods Lei Miao, Sakae Tanemura, Shoichi Toh, Kenji Kaneko, Masaki Tanemura J. Mater. Sci. Technol., 2004, 20 (Supl.): 59-62.  Abstract   HTML   PDF (650KB) The controlled growth of densely assembled single-phase rutile-TiO2 nanorods was demonstrated by a heating-sol-gel template process with about $\sim$300~nm in diameter and several micrometers in length. Transmission electron microscopic observation reveals these rutile-TiO2 nanorods are the aggregates of many nanocrystallites grown preferentially to the [110] zone axis direction with about 10~30 nm in diameter. The calculation and comparison of d-spacing values with those of bulk values suggest the crystal structure of nanorods close to bulk materials. Selected area electron diffraction and energy dispersive X-ray spectroscopy measurements confirm that the obtained nanorods are rutile-TiO2 nanorods with good compositional uniformity and consist of distinct shape of nanocrystallites with 10～30 nm diameter.
 Select Synthesis of Ga2O3 Nanowires by Arc Plasma C.Arnoult, X.Devaux J. Mater. Sci. Technol., 2004, 20 (Supl.): 63-64.  Abstract   HTML   PDF (222KB) Gallium oxide nanowires have been successfully synthesized by DC arc plasma without the use of any catalyst. The nanowires have been identified to be β-Ga2O3. Their diameters are ranging from 5 to 15 nm and maximal lengths can attain 10μm. The microstructural study of the gallium anode shows that nanowires grew from it. These results are compared with previous work on Al2O3 nanowires growth by the same method. Several assumptions of growth are proposed.
 Select Manufacturing and Low-Velocity Impact Response of a New Composite Material: Metal Porous Polymer Composite (MPPC) X.L.Gong, Y.Liu, S.Y.He, J.Lu J. Mater. Sci. Technol., 2004, 20 (Supl.): 65-68.  Abstract   HTML   PDF (537KB) Three types of metal porous polymer composite (MPPC) were produced by infiltrating different polymers into a porous Al structure. This type of interpenetrating microstructure allows for a better combination of mechanical and physical properties. The low velocity impact response of these composites was investigated by conducting drop-weight impact tests. Impact parameters such as the peak load, the time to peak load, the deflection at peak load, and the absorbed energy were evaluated and compared for Al, MPPC and pure Al foam. The influence of the volume fraction of polymer was also investigated for the above impact parameters. The experimental results indicate that the inlaid polymer has a very important positive effect on the impact behavior and improves the characteristics of the composite in comparison with conventional foam and pure Al.
 Select Variational and Microstructure-Independent Relations for Piezoelectric Composites Q.-C. He J. Mater. Sci. Technol., 2004, 20 (Supl.): 69-72.  Abstract   HTML   PDF (152KB) The Hill-Mandel lemma is first extended to piezoelectricity. It is then shown that, when the macroscopic variable couple is fixed and when the local piezoelectric tensor field is subjected to a variation, the variation of the macroscopic energy is equal to the volume average of the variations of the microscopic energy. This variational relation is finally used to derive microstructure-independent relations.
 Select X-ray Diffraction Measurement of Residual Stress in PZT Thin Films Prepared by MOD with the Extended Model Suifeng DENG, Xuejun ZHENG, Jiantao YANG, Yichun ZHOU J. Mater. Sci. Technol., 2004, 20 (Supl.): 73-77.  Abstract   HTML   PDF (437KB) Pb(Zr0.52Ti0.48)O3 (PZT) thin films were deposited on Pt/Ti/SiO2/Si(001) by metal organic decomposition (MOD) at different annealing temperatures. D500 X-ray diffractometer and texture goniometer were used to analyze the crystalline phases and measure diffraction angles θ and their changes with different orientations Ψ, respectively. Based on the extended model, the residual stress in PZT thin films with sin2\it \Psi\$ method was measured. The origin of residual stress was theoretically analyzed from the epitaxial stress, intrinsic stress, thermal stress, and transformation stress. For the validity to evaluate residual stress, the experimental results of the conventional and extended models and theoretical analysis were discussed. One can conclude that the theoretical results are closer to the experimental results evaluated by the extended model, and the residual compressive stress evaluated by the extended model is larger than that evaluated by the conventional model due to the consideration of the piezoelectric coupling effects.
 Select Residual Stress and Microscratch Resistance of Au/NiCr/Ta Multilayered Films Wu TANG, Kewei XU J. Mater. Sci. Technol., 2004, 20 (Supl.): 78-80.  Abstract   HTML   PDF (289KB) Au/NiCr/Ta multilayered metallic films deposited on Al2O3 substrate by magnetron sputtering have been used in microwave integrated circuits (MIC). The residual stress and scratch resistance were investigated at different deposition temperature. The residual stress in as-deposited films was of tension with 155 MPa～400 MPa and changed to compression after samples annealing. It was found that both friction and acoustic emission modes can eventually be used for conventionally critical load determination, the critical characteristic load at each point corresponding to abrupt change of the friction coefficient was not sensitive to deposition temperature, but sensitive to the film thickness. Critical load is less sensitive to the change of residual stress by microscratch method.
 Select Residual Stresses in Coating Technology G.Montay, A.Cherouat, A.Nussair, J.Lu J. Mater. Sci. Technol., 2004, 20 (Supl.): 81-84.  Abstract   HTML   PDF (603KB) Residual stress in coatings is the result of individual particle stress. Their effects may be either beneficial or detrimental, depending upon the magnitude, sign and distribution of the stresses with respect to the external load. Tensile stress which exceeds the elastic limit causes cracking in surface coatings or at the interface between the substrate and the coat. Compressive stress, in general, has a beneficial effect on the fatigue life, crack propagation, coating adhesion and on the durability of the top coat during service. Compressive residual stresses can increase the number of cycles before crack initiation begins through a mean stress effect. Temperature gradients which occur during solidification and subsequent cooling are the principal mode of internal stresses generation. Some parameters influence the residual stress field of both the coating and the substrate. Substrate nature, spraying temperature, thickness of the coat layer, substrate preparation (grit blasting conditions), and velocity of the splats are in the relation with the quality of the coating. In this work, we will describe the role playing by the ceramics coating elaboration on the residual stress gradient in depth of the component. The incremental hole drilling technique has been developed to determine the residual stress gradient in depth of the coat and substrate which must be used with particularly conditions. This new technology has been employed on zirconia, alumina and tungsten carbide plasma sprayed coating.
 Select Characterization of Detonation Sprayed Thermal Barrier Coatings Fuhe YUAN, Zhiwei HUANG, Zhongguang WANG, Chao SUN, Shijie ZHU J. Mater. Sci. Technol., 2004, 20 (Supl.): 85-88.  Abstract   HTML   PDF (692KB) Detonation spraying has advantages of strong bonding without heating substrates, high coating speed, low requirements for the quality of surface treatment of substrates and others. In the present research, yttria stabilized zirconia powders were used for detonation spraying thermal barrier coatings (TBCs) on a Ni-base superalloy with a bond coat of NiCrAlY. Thermal exposure tests were conducted at a constant temperature in air. After thermal exposure, microstructure observation, element distribution analysis and hardness measurement were carried out. The cracking behavior of the as-prepared and preoxidized TBCs specimens was investigated.
 Select An Alternative Sol-Gel Method Applied to TiO2 Coating on Al Scale Fiber Lei Miao, Sakae Tanemura, Thi Hue Nguyen, Li Luo, Masaki Tanemura, Shoichi Toh, Kenji Kaneko, Masahiro Kawasaki J. Mater. Sci. Technol., 2004, 20 (Supl.): 89-92.  Abstract   HTML   PDF (502KB) An alternative sol-gel method has been applied to fabricate anatase and rutile TiO2 coatings uniformly on Al scale fibers with very thin naturally oxidized layer from mixed precursors of Ti tetraisopropoxide, acetyl acetone, deionizer water and ethanol in different molar ratios. The crystal structure of TiO2 coatings on Al scale fiber was confirmed by both XRD and TEM. The surface morphology of the coatings was observed by SEM and the chemical composition of the grown TiO2 was analyzed by EDS in TEM. Anatase coating, having a fine crystalline structure, was grown at 450℃ while rutile was being done at 670℃. The TEM results indicated that the fabricated TiO2 coatings consisted of anatase/rutile polycrystalline structures. The optimal fabrication conditions for TiO2 coatings with about 400 nm in thickness on Al scale fibers were established through the characterization results.
 Select Thermal Shock Damage of Hot-work Tool Steel AISI H11 in Hard Turned, Electroeroded, Shot-peened or Deep Rolled Surface Conditions M.Krauss, B.Scholtes J. Mater. Sci. Technol., 2004, 20 (Supl.): 93-96.  Abstract   HTML   PDF (747KB) The lifetime of hot-work tools is often limited by the development of thermal shock cracks. To analyze the influence of near-surface materials states on the damage process during thermal shock loading, isothermal annealing experiments and thermal shock tests with hot-work tool steel AISI H11 in hard turned, electroeroded, shot-peened or deep rolled surface conditions were performed. Cyclic thermal shock tests were carried out by heating and subsequent quenching of specimens. Crack depths and crack densities were investigated after 100, 1000, 10000 and 30000 cycles at microsections using optical microscopy. Complementary, residual stresses were determined by X-ray diffraction-(XRD) stress analysis. Under identical thermal loading conditions characteristic cracking behaviour was observed at different surface types examined. Neither deep rolling nor shot-peening results in decreasing crack lengths compared to hard turned surface conditions. While the residual stress state during simple annealing is proportionally stable, almost all initial residual stresses relaxed during a few hundred thermal shock cycles. Additional Martens-hardness measurements and FWHM values of XRD analyses indicate that the work hardening induced by mechanical surface treatment is not stable under thermal shock loading.
 Select Super-steel Produced by Unrecrystallized Austenite Region Rolling in High-speed Wire Mill Lin HU, Xiaodong HU, Peng GAO, Hongyang ZHAO, Dong-Ying Ju J. Mater. Sci. Technol., 2004, 20 (Supl.): 97-100.  Abstract   HTML   PDF (328KB) Based on the discussing of the mechanisms of grain refinement strengthening and deformation induced transformation, the characteristics of controlled rolling and controlled cooling for high-speed wire were analyzed. Aiming at the problems of wire mill in Anshan Iron & Steel Co., turbulent cooler and spray cooler on the Stelmor conveyor were developed. Super-steels had been developed for Q235 steel through unrecrystallized austenite region rolling. The constitution and properties of the wire on the coil overlap zone were also improved. This proved the possibility that super-steels can be developed in high-speed wire mill.
 Select Effect of Shot Peening on Surface Integrity—Influence of Low Temperature Heating Katsuji Tosha, Jian Lu, Bruno Guelorget J. Mater. Sci. Technol., 2004, 20 (Supl.): 101-104.  Abstract   HTML   PDF (686KB) The effect of shot peening on surface integrity was described. After shot peening was performed for carbon steel under several conditions with steel shot, peened materials were heat-treated at various temperatures and times (100~600℃, 15~240 min), and then hardness, half width and surface residual stress were measured. The following results are obtained: (1) non-affected layer induces compressive residual stresses on the peened surface and surface layer, (2) hardness increases after heating at 200~400℃, but decreases in case of 600℃, (3) compressive residual stresses decrease after all heat treatments, (4) microstructure may be recovered by heat treatment at low temperature
 Select Evaluation on Microstructure of Thin Strip Produced by Twin-Roll Continuous Casting Hongyang ZHAO, Dong-Ying Ju, Lin HU J. Mater. Sci. Technol., 2004, 20 (Supl.): 105-107.  Abstract   HTML   PDF (375KB) The twin-roll casting (TC) process of Al alloy was presented. Microstructure and crystallization of the as-cast strip are investigated to link the strip quality and microstructure with the process conditions. The process variables of cooling rate, temperature history and solidification finish point and their influences are discussed. The results revealed the ability of the twin-roll caster to produce directly the thin strip of Al alloy with improved mechanical strength.
 Select A New Low-Temperature Sintering Method and Characteristic Evaluation of Ferrite Magnetic Materials P.Bian, Dong-Ying Ju J. Mater. Sci. Technol., 2004, 20 (Supl.): 108-110.  Abstract   HTML   PDF (394KB) Magnetite (Fe3O4) of ferrite magnetic materials has attracted attentions arising by the chip coil electronic material. However, its industrial applications have been limited by the need of high temperature sintering under reduced pressure or vacuum. In order to develop the process method of low-cost and energy saving with high strength and high magnetism of the magnet, a new low temperature sintering method during CO2 gas and adding small amount of boric acid (H3BO3) are proposed. Here, the superfine magnetite powder was fabricated by decomposition from ferrous oxalate at 500℃ in CO2 gas. The ferrous oxalate was synthesized using iron chloride and ammonium oxalate with the liquid phase precipitation. The magnetite powder compact was produced by Newton press and CIP (cold isostatic press) after adding small amount of boric acid. In this study, the effects of the additive on the mechanical and magnetic properties of the sintered magnet were also evaluated. By characteristic evaluation of the magnet, the validity of the proposed new low-temperature sintering process and the optimal process conditions were confirmed.
 Select Study of the Transverse Cracking and Stiffness Loss in Hygrothermal Aged Cross-Ply Laminates E.A.Adda-Bedia, A.Tounsi, K.H.Amara, S.Meftah J. Mater. Sci. Technol., 2004, 20 (Supl.): 111-113.  Abstract   HTML   PDF (251KB) To investigate the transverse cracking of the aged cross-ply laminates, subjected to uniaxial tensile loading. For quasistatic tests, most cracks, initiated in the 90℃ plies, instantaneously cross the entire test specimen width from edge to edge. In this case, the investigation of transverse cracking is reduced to a two-dimensional analysis. In the other hand, when the laminate is subjected initially to the environmental conditions, the material properties will be affected by the variation of temperature and moisture, and are based on a micromechanical model of laminates. Consequently, the hygrothermal conditions degrade the stiffness of the laminate. This degradation is taken into account to assess the changes of the longitudinal modulus due to transverse cracking.
 Select Stress-Strain Response of Biomaterials by a Digital Image Correlation Method: Application to Tecoflex N.Bahlouli, S.M'Guil, S.Ahzi, M.Laberge J. Mater. Sci. Technol., 2004, 20 (Supl.): 114-116.  Abstract   HTML   PDF (380KB) A digital image correlation method is used to characterize the mechanical response of a polyurethane rubber (Tecoflex). Stress-strain curves under a tensile test for large deformations are measured using this technique along with the evolution of volume change. Loading-unloading stress-strain curves were also measured. A network model for large nonlinear rubber elasticity is used, with simplifying assumptions and fairly good results was obtained compared to the experimental data.
 Select Machining Characteristics of Two Different Materials in Surface Polishing Yan CHEN, Y, ong GONG J. Mater. Sci. Technol., 2004, 20 (Supl.): 117-119.  Abstract   HTML   PDF (289KB) The magnetic abrasive machining is a method that the magnetic field (lines of magnetic force) is used to precisely machine the surface of the workpiece. When it is a magnetic workpiece, and the workpiece is magnetized and then becomes a new magnetic pole. On the contrary, when it is nonmagnetic workpiece, it can not be magnetized. In this research, the precise processing phenomenon and the condition on a shaft with steps are examined based on the experiment result mentioned above.
 Select Repair of Multi Cracks Concrete Sewers Systems S.Kesteloot, C.Djelal, S.Baraka, I.Benslimane J. Mater. Sci. Technol., 2004, 20 (Supl.): 120-122.  Abstract   HTML   PDF (315KB) Man-entry sewers sustain many types of structural deterioration, and current repair techniques are very costly. Our objective was therefore to apply methods of localised strengthening by the adhesion of composite plates, as currently used in the construction and public works industry. To do so, it was necessary to run numerical simulations to determine the behaviour and mechanism of the ovoid sewer sections, to ascertain which areas required strengthening. A scale-1 experiment series was carried out to validate the process on reinforced-concrete multicracked ovoid sewers.
 Select Electrical Characterization of Doped Silicon Using High-Frequency Electromagnetic Waves Yang Ju, Yasushi Ohno, Hitoshi Soyama, Masumi Saka J. Mater. Sci. Technol., 2004, 20 (Supl.): 123-124.  Abstract   HTML   PDF (202KB) A method for electrical characterization of doped silicon in a contactless fashion using high-frequency electromagnetic waves was presented. A focusing sensor was used to focus a 110 GHz microwave on the surface of a silicon wafer. The amplitude and phase of the reflection coefficient of the microwave signal were measured, by which electrical conductivity of the wafer was determined quantitatively, independent of the permittivity and thickness of the wafer. The conductivity obtained by this method agrees well with that measured by the conventional four-point-probe method.
 Select Recycling Study of End of Life Products Made of ABS Resin O.Mantaux, T.Lorriot, L.Chibalon, J.Aurrekoetxea, A.Puerto, A.Arostegi, I.Urrutibeascoa J. Mater. Sci. Technol., 2004, 20 (Supl.): 125-128.  Abstract   HTML   PDF (533KB) Former studies about ABS recycling show a very slight decrease of performances after several cycles of accelerated ageing and reprocessing, which proves the benefit of ABS as a recyclable material. Nevertheless, few studies consider ABS properties after real service ageing. The study proposed here is focused on properties of ABS after service and reprocessing. This work evaluates mechanical, thermal and chemical properties of ABS products that have been heated and cooled many times after two types of recycling processes: a recycling process involving grinding and extrusion is compared to a chemical recycling process with the use of a solvent. This study shows that it is possible to optimize treatment and reprocessing conditions in order to produce a recycled ABS corresponding to performance specifications of ABS users.
 Select Synthesis and Characterization of Some Substituted Arylimidazole Derivatives Zhiqiang ZHANG, Ren HE, Peng LEI, Yan GAO, Haijun CHI, Zhizhi HU J. Mater. Sci. Technol., 2004, 20 (Supl.): 129-132.  Abstract   HTML   PDF (235KB) The incorporation of the imidazole nucleus is an important strategy in pharmaceuticals, chemiluminescence and electroluminescence. A facile synthesis of some aryl substituted imidazole derivatives from substituted benzils and substituted benzaldehydes via Debus reaction is described. Their structures were identified by IR, MS, NMR and their characteristics were evaluated by UV-visible and fluorescence spectroscopy.
 Select Determination of Thermal Decomposition Kinetics Parameters of Waste Plastics by Means of Thermogravimetry Xincheng MIAO, Chongmin ZHANG, Shuwen CHEN, Hao YUAN J. Mater. Sci. Technol., 2004, 20 (Supl.): 133-134.  Abstract   HTML   PDF (223KB) The thermal decomposition kinetics of waste plastics through thermogravimetry with temperature programmed heating in Ar atmosphere was reported. Based on the experimental results, the kinetics parameters of some waste plastics were calculated. The results show that apparent active energies of selecting plastics are between 100.72～225.89 kJ/mol.
 Select Experiment on Iron Scrap Reduction by Adding Waste Plastics into Scrap Column Shuwen CHEN, Chongmin ZHANG, Yuchun ZHAI J. Mater. Sci. Technol., 2004, 20 (Supl.): 135-137.  Abstract   HTML   PDF (311KB) Simulating to the condition of iron powder production in Hoganas process, the reduction experiments of iron scrap were done by adding different kinds of typical chlorine free waste plastics in China into the scrap column. In this work, the influences of variety of waste plastics added and experiment temperature on the iron scrap reduction rates were studied by thermogravimetric analyses. Moreover, the remained pore canals made by the gasification of the waste plastics were investigated with microscopes. Furthermore, the effect of the remained pores in the column on the iron scrap reducing reaction between gas and solid phases was discussed.
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