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.

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      28 September 2007, Volume 23 Issue 05 Previous Issue    Next Issue
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    Research Articles
    Recent Progress of Counter Electrodes in Nanocrystalline Dye-sensitized Solar Cells
    Kexin LI, Zhexun YU, Yanhong LUO, Dongmei LI, Qingbo MENG
    J. Mater. Sci. Technol., 2007, 23 (05): 577-582. 
    Abstract   HTML   PDF (959KB)
    Dye-sensitized solar cell (DSC) consists a combination of several different materials: photoanodes with nanoparticulated semiconductors, sensitizers, electrolytes and counter electrodes (CEs). Each materials performs specific task for the conversion of solar energy into electricity. The main function of CE is to transfer electrons to the redox electrolyte and regenerate iodide ion. The work of CE is mainly focused on the studies of the kinetic performance and stability of the traditional CEs to improve the overall efficiency of DSC, seeking novel design concepts or new materials. In this review, the development and research progress of different CE materials and their electrochemical performance, and the problems are discussed.
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    Microstructure Characterization of Single-crystal ZnO Nanorods Synthesized by Solvothermal at Low Temperature
    Chunna YANG, Ying LI, Ge XU, Xiuliang MA
    J. Mater. Sci. Technol., 2007, 23 (05): 583-586. 
    Abstract   HTML   PDF (514KB)
    Single-crystalline ZnO nanorods have been synthesized by a simple solvothermal process at low temperature.Transmission electron microscopy (TEM) observations have confirmed that the as-synthesized products have rod-like morphologies with diameters ranging from several nanometers to 30 nm and lengths from 100 nm to 2 μm. Such hexagonal ZnO nanorods are structurally uniform and the growth direction is identified to be [0001]. Growth mechanism of the ZnO nanorods was proposed.
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    Synthesis and Characterization of Nickel Nanorods Transferred from Hydrotherally Decomposed Rod-like NiS
    Yu LUO, Jiancheng ZHANG, Yue SHEN, Shutao JIANG, Guoyong LIU
    J. Mater. Sci. Technol., 2007, 23 (05): 587-590. 
    Abstract   HTML   PDF (388KB)
    Powders of hexagonal-structured single-crystalline nickel sulfide nanorods have been synthesized in cetyltrimethyl ammonium bromide (CTAB)/water/hexane/n-pentanol quaternary microemulsion under hydrothermal conditions by using the reaction of carbamide and carbon disulfide as a sulfide source. Single-crystalline nickel nanorods have been synthesized via thermal decomposition by using single-crystalline nickel sulfide nanorods as precursor. The influence of different reaction parameters on the morphology of the products has been investigated. The structure, morphology and magnetic properties of the products were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), thermogravimetric analysis-differential scanning calorimeter (TGA-DSC) and vibrating sample magnetometer (VSM). The results of magnetic measurements showed that the specific saturation magnetization (σs) and coercivity values (Hc) of nickel nanorods were 37.5 emu/g and 68.5 Oe, respectively.
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    Preparation and Electrocatalytic Activity of Tungsten Carbide Nanorod Arrays
    Huajun ZHENG, Zhenhai GU, Jinhuan ZHONG, Wei WANG
    J. Mater. Sci. Technol., 2007, 23 (05): 591-594. 
    Abstract   HTML   PDF (921KB)
    High density tungsten carbide nanorod arrays have been prepared by magnetron sputtering (MS) using the aluminum lattice membrane (ALM) as template. Electrocatalytic properties of nitromethane electroreduction on the tungsten carbide nanorod arrays electrode were investigated by electrochemical method, and their electrocatalytic activity is approached to that of the Pt foil electrode.
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    Densification Behavior of Nanocrystalline Mg2Si Compact in Hot-pressing
    Wei XIONG, Xiaoying QIN, Li WANG
    J. Mater. Sci. Technol., 2007, 23 (05): 595-598. 
    Abstract   HTML   PDF (522KB)
    Densification behavior of nanocrystalline Mg2Si (n-Mg2Si) with grain size about 30–50 nm was investigated by hot-pressing at 400℃. The results indicated that the densification process of n-Mg2Si exhibited three linear segments: p<0.3 GPa, 0.3 GPa1.2 GPa determined by Heckel formula, among which the third fast increasing segment in high pressure range p>1.2 GPa has seldom been reported in conventional coarse-grained polycrystalline materials. Nevertheless, in the whole pressure range (0.125–1.500 GPa) investigated the densification behavior of n-Mg2Si can be well described by a Kawakita formula p/C=(1/a)p+1/(ab) with constant a=0.452 being in good agreement with the initial porosity of the com
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    Study on the Modification of Nanodiamond with DN-10
    Yongwei ZHU, Feng XU, Jianliang SHEN, Baichun WANG, Xiangyang XU, Jianbin SHAO
    J. Mater. Sci. Technol., 2007, 23 (05): 599-603. 
    Abstract   HTML   PDF (605KB)
    Fourier transform infrared spectroscopy (FT-IR) and ζ-potential were introduced to study the effect of different modification parameters on the surface properties of nanodiamond (ND). Results showed that under stirring grinding conditions, ND hard aggregates were smashed and some active spots on them reacted with surfactant molecules, which led to the increase in its ³-potential and stability. Different models of surface modification were also given in this study.
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    Comparison Study on the Microstructure of Nanocrystalline TiO2 in Different Ti-Si Binary Oxides
    Luyan WANG, Yanping SUN, Bingshe XU
    J. Mater. Sci. Technol., 2007, 23 (05): 604-610. 
    Abstract   HTML   PDF (978KB)
    Three different Ti-Si oxide structuares, silica supported titania, silica coated titania and intimately mixed silicatitania, containing 10%–40% SiO2, were made by sol-gel process. The variations of microstructure parameters of nanocrystalline (nc) TiO2-anatase in the three kirds of binary oxides, including in-plane spacing d, cell constants (a0, c0), cell volume V , cell axial ratio c0/a0 and crystal grain size, were comparatively investigated by high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). It is found that the microstructure parameters vary remarkably with increasing SiO2 content and annealing temperature. Different structured Ti-Si binary oxides lead to different variation tendencies of microstructure parameters. The more SiO2 the binary oxide contains, the more lattice defects of nc TiO2-anatase appear; diffusion or migration of Si cations could be an important influential factor in the variations of microstructure. The grain size of nc TiO2 in the three kinds of binary oxides not only depends on SiO2 content and annealing temperature but also on the degree of lattice microstrain and distortion of nc TiO2-anatase. Both grain size and phase transformation of nc TiO2-anatase are effectively inhibited with increasing SiO2 content.
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    Growth of TiO2 Nanorods by Sol-gel Template Process
    A.Sadeghzadeh Attar, Sh.Mirdamadi, F.Hajiesmaeilbaigi, M.Sasani Ghamsari
    J. Mater. Sci. Technol., 2007, 23 (05): 611-613. 
    Abstract   HTML   PDF (558KB)
    In this work, TiO2 nanorods with uniform diameter of about 100 nm and a length of several micrometers were successfully prepared by the sol-gel template method. Also the influence of molar ratios of precursor on the morphology and structure of TiO2 nanorods has been investigated. The prepared samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD results indicated that the TiO2 nanorods were crystallized in the anatase and rutile phases, after annealing to 400–700℃ up to 2
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    Effect of Low Feed Rate FSP on Microstructure and Mechanical Properties of Extruded Cast 2285 Aluminum Alloy
    L.Karthikeyan, V.S.Senthilkumar, D.Viswanathan, S.Natarajan
    J. Mater. Sci. Technol., 2007, 23 (05): 614-618. 
    Abstract   HTML   PDF (2168KB)
    Friction stir processing (FSP), a variation of FSW (friction stir welding) is an emerging surface engineering technology that can locally eliminate casting defects and refine microstructures, thereby improving the mechanical properties of material. FSP can also produce fine grained microstructures through the thickness to impart superplasticity. The technology involves plunging a rapidly rotating, non consumable tool, comprising a profiled pin and larger diameter shoulder, into the surface and then traversing the tool across the surface. The pin and the shoulder friction heat the surface which alters the grain structure in the processed area thereby improving the mechanical properties. This paper presents the effects of FSP on microstructure and mechanical properties of extruded cast 2285 aluminum alloy at three different feed rates viz. 10, 12 and 15 mm/min. With the increase in the feed speed the material was observed to have increased impact strength. FSP also increased the tensile and yield strengths with increases in hardness and ductility values also. The observation has been listed in detail and pictorially represented.
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    A Model for Evaluation of Grain Sizes of Aluminum Alloys with Grain Refinement Additions
    Zhongwei CHEN, Zhi HE, Wanqi JIE
    J. Mater. Sci. Technol., 2007, 23 (05): 619-622. 
    Abstract   HTML   PDF (336KB)
    Based on the assumption that the nucleation substrates are activated by constitutional undercooling generated by an adjacent grain growth and solute distribution during the initial solidification, a model for calculation of the grain size of aluminum alloys with the grain refinement is developed, where the nucleation is dominated by two parameters, i:e. growth restriction factor Q and the undercooling parameter P. The growth restriction factor Q is proportional to the initial rate of constitutional undercooling development and can be used directly as a criterion of the grain refinement in the alloys with strong potential nucleation particles. The undercooling parameter P can be regarded as the maximum of constitutional undercooling △Tc. For weak potential nucleation particles, the use of RGS would be more accurate. The experimental data of the grain refinement of pure aluminum and AlSi7 alloys are coincident predicted results with the model.
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    Role of Chloride Ion and Dissolved Oxygen in Electrochemical Corrosion of AA5083-H321 Aluminum-Magnesium Alloy in NaCl Solutions under Flow Conditions
    K.Jafarzadeh, T.Shahrabi, S.M.M.Hadavi, M.G.Hosseini
    J. Mater. Sci. Technol., 2007, 23 (05): 623-628. 
    Abstract   HTML   PDF (1759KB)
    Flow-induced corrosion consists electrochemical and mechanical components. The present paper has to assessed the role of chloride ion and dissolved oxygen in the electrochemical component of flow induced corrosion for AA5083-H321 aluminum-magnesium alloy which is extensively used in the construction of high-speed boats, submarines, hovercrafts, and desalination systems, in NaCl solutions. Electrochemical tests were carried out at flow velocities of 0, 2, 5, 7 and 10 m/s, in aerated and deaerated NaCl solutions with different sodium chloride concentrations. The results showed that the high rate of oxygen reduction under hydrodynamic conditions causes an increase in the density of pits on the surface. The increase of chloride ions concentration under flow conditions accelerates the rate of anodic reactions, but have no influence on the cathodic reactions. Thus, in the current work, it was found that under flow conditions, due to the elimination of corrosion products inside the pits, corrosion resistance of the alloy is increased.
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    Investigation of La9:33Si6O26 Oxygen Ionic Conductor
    Hong ZHANG, Zhicheng LI, Bill Bergman, Xiaodong ZOU
    J. Mater. Sci. Technol., 2007, 23 (05): 629-632. 
    Abstract   HTML   PDF (1119KB)
    La9:33Si6O26 oxygen ionic conductor was synthesized by solid state reaction method. Its structure was determined by single-crystal X-ray diffraction analysis at room temperature. The results showed that La9:33Si6O26 oxide has the apatite structure with space group P63/m. AC impedance measurements indicated that the oxides sintered in nitrogen have much higher conductivity than those sintered in air. The effects of grain boundaries on the conductivity were discussed.
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    Preparation of Polycrystalline Singe-phase K0:3MoO3 by Hot Isostatic Pressing Sintering
    Junfeng WANG, Rui XIONG, Ning SHU, Jing SHI, Zhengzhong JIN
    J. Mater. Sci. Technol., 2007, 23 (05): 633-636. 
    Abstract   HTML   PDF (456KB)
    Nearly single-phase and polycrystalline charge-density-wave compound K0:3MoO3 have been prepared by using a simple method. In this work, K2CO3 and MoO3 were used as starting materials and reacted by hot isostatic pressing (HIP) sintering. The product is nearly single phase K0:3MoO3 determined by X-ray powder diffraction (XRD) and energy dispersive spectroscopy (EDS). Measurement of temperature dependence of resistivity reveals that the transport property of polycrystalline K0:3MoO3 obviously differs from that of single crystal due to the grain boundaries and the anisotropic structure in this kind of compound.
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    Steady State Rheological Characteristic of Semisolid Magnesium Alloy
    Fengyun YAN, Liping SUN, Yi GONG, Yuan HAO
    J. Mater. Sci. Technol., 2007, 23 (05): 637-640. 
    Abstract   HTML   PDF (524KB)
    Isothermal compressive experiments at different temperatures, strain rates and holding time for semisolid AZ91D, Zr modified AZ91D and MB15 alloy with higher solid volume fraction were carried out by using Gleeble–1500D simulator and the true stress-strain curves were given directly. The relationship of apparent viscosity vs temperature, shear rate and holding time of the three kinds of semi-solid magnesium alloys, as well as isothermal steady state rheological characteristic and mechanical behavior were studied. The results show that the three magnesium alloys had the characteristic of shear-thinning. The rheological characteristic of the semi-solid MB15 is different from that of semi-solid AZ91D. The semi-solid MB15 has higher apparent viscosity and deformation resistance.
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    SiCp/Al Composites Fabricated by Modified Squeeze Casting Technique
    Shoujiang QU, Lin GENG, Jiecai HAN
    J. Mater. Sci. Technol., 2007, 23 (05): 641-644. 
    Abstract   HTML   PDF (938KB)
    A cost effective method was introduced to fabricate pure aluminum matrix composites reinforced with 20% volume fraction of 3.5 μm SiC particles by squeeze casting followed by hot extrusion. In order to lower volume fraction of the composites, a mixed preform containing pure aluminum powder and the SiC particles was used. The suitable processing parameters for the infiltration of pure aluminum melt into the mixed preform are: melt temperature 800℃, preform temperature 500℃, infiltration pressure 5 MPa, and solidification pressure 50 MPa. Microstructure and properties of the composites in both as-cast and hot extruded states were investigated. The results indicate that hot extrusion can obviously improve the mechanical properties of the composite.
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    Effect of Cooling Conditions on Grain Size of AZ91 Alloy
    Zhiliang NING, P.CAO, H.WANG, Jianfei SUN, Diankun LIU
    J. Mater. Sci. Technol., 2007, 23 (05): 645-649. 
    Abstract   HTML   PDF (1267KB)
    The grain size of AZ91 alloy was investigated in terms of the effects of cooling rate, superheat and steel gauze. It was found that rapid cooling rate and low superheat favoured the achievement of fine grain structures. The gauze had a less profound effect on the grain size in AZ91 magnesium alloy than that in A356 aluminum alloy. The mechanisms by which these factors affect grain refinement of AZ91 have also been discussed.
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    Time Dependant Weld Shape in Ar-O2 Shielded Stationary GTA Welding
    Shanping LU, Dianzhong LI, Hidetoshi Fujii, Kiyoshi Nogi
    J. Mater. Sci. Technol., 2007, 23 (05): 650-654. 
    Abstract   HTML   PDF (1561KB)
    The stationary gas tungsten arc welding (GTA) is carried out on SUS304 stainless steel under Ar-0.1%O2 and Ar-0.3%O2 mixed shielding to observe the evolution of the molten pool and investigate the role of Marangoni convection on the weld shape. After welding, the oxygen content in the weld metal was measured by using an oxygen/nitrogen analyzer. Small addition of oxygen to the argon based shielding gas can effectively adjust the weld pool oxygen content. Oxygen plays an important role as an surface active element in determining the pattern of Marangoni convection in the stainless steel weld pool. When the weld metal oxygen content is over the critical value, 0.01 wt pct, corresponding to the Ar-0.3%O2 mixed shielding gas, the Marangoni convection changes from outward to inward direction and the weld shape dramatically changes from wide shallow shape to narrow deep shape.
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    Synthesis of Nano-sized Barium Titanate Powder by Solid-state Reaction between Barium Carbonate and Titania
    U.Manzoor, D.K.Kim
    J. Mater. Sci. Technol., 2007, 23 (05): 655-658. 
    Abstract   HTML   PDF (391KB)
    Size control of BaTiO3 in solid-state reaction between BaCO3 and TiO2 was demonstrated by varying the size of TiO2 and milling conditions of BaCO3. The smaller TiO2 particles had higher surface area, resulting in faster initial reaction. The mechanically milled BaCO3 particles accelerated the diffusion process and decreased the calcinations temperature. It can be deduced from the results that the size control is possible and nano-sized BaTiO3 particles with about 60 nm can be synthesized by using the conventional solid-state reaction between BaCO3 and TiO2
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    Effect of Microstructure Refinement on the Strength and Toughness of Low Alloy Martensitic Steel
    Chunfang WANG, Maoqiu WANG, Jie SHI, Weijun HUI, Han DONG
    J. Mater. Sci. Technol., 2007, 23 (05): 659-664. 
    Abstract   HTML   PDF (2665KB)
    Martensitic microstructure in quenched and tempered 17CrNiMo6 steel with the prior austenite grain size ranging from 6 μm to 199 μm has been characterized by optical metallography (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The yield strength and the toughness of the steel with various prior austenite grain sizes were tested and correlated with microstructure characteristics. Results show that both the prior austenite grain size and the martensitic packet size in the 17CrNiMo6 steel follow a Hall-Petch relation with the yield strength. When the prior austenite grain size was refined from 199 μm to 6 μm , the yield strength increased by 235 MPa, while the Charpy U-notch impact energy at 77 K improved more than 8 times, indicating that microstructure refinement is more effective in improving the resistance to cleavage fracture than in increasing the strength. The fracture surfaces implied that the unit crack path for cleavage fracture is identified as being the packet.
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    Systematic Study of Nanocrystalline Plasma Electrolytic Nitrocarburising of 316L Austenitic Stainless Steel for Corrosion Protection
    M.Aliofkhazraei, P.Taheri, A.Sabour Rouhaghdam, Ch.Dehghanian
    J. Mater. Sci. Technol., 2007, 23 (05): 665-671. 
    Abstract   HTML   PDF (520KB)
    A number of studies have been reported on the use of nanocrystalline plasma electrolytic nitrocarburising technology for surface hardening of stainless steels for higher corrosion resistance resulted from this technique. However, very few studies have focused on the optimization of the nanocrystalline plasma electrolytic nitrocarburising process parameters. In this study, a design of experiment (DOE) technique, the Taguchi method, has been used to optimize the nanocrystalline plasma electrolytic nitrocarburising not only for surface hardening but also for the corrosion protection of 316L austenitic stainless steel by controlling the coating process's factors. The experimental design consisted of four factors (Urea concentration, electrical conductivity of electrolyte, voltage and duration of process), each containing three levels. Potentiodynamic polarization measurements were carried out to determine the corrosion resistance of the coated samples. The results were analyzed with related software. An analysis of the mean of signal-to-noise (S/N) ratio indicated that the corrosion resistance of nanocrystalline plasma electrolytic nitrocarburised 316L stainless steel was influenced significantly by the levels in the Taguchi orthogonal array. The optimized coating parameters for corrosion resistance are 1150 g/L for urea concentration, 360 mS/cm for electrical conductivity of electrolyte, 260 V for applied voltage, 6 min for treatment time. The percentage of contribution for each factor was determined by the analysis of variance (ANOVA). The results showed that the applied voltage is the most significant factor affecting the corrosion resistance of the coatings.
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    New Vitrified Bond Diamond Grinding Wheel for Grinding the Cylinder of Polycrystalline Diamond Compacts
    Xiaofu ZHANG, Anxian LU, Yu WANG
    J. Mater. Sci. Technol., 2007, 23 (05): 672-676. 
    Abstract   HTML   PDF (696KB)
    In this work, a kind of new vitrified bond based on Li2O-Al2O3-SiO2 glass ceramics was used to bond the diamond grains, which is made into grinding wheel and the cylindrical grinding process of polycrystalline di mond compacts (PDCs) by using the new vitrified bond diamond grinding wheel was discussed. Several factors which influence the properties of grinding wheel such as amount of vitrified bond and the kinds and amount of stuff in grinding wheel were also investigated. It was found that the new vitrified bond can firmly combine diamond grains, when there are only diamonds and vitrified bond in the structure of grinding wheel, the longevity of the grinding wheel is about 2.5–3 times as that of resin bond grinding wheel for processing PDCs. The grinding size precision of PDCs can be improved from ±0.03 mm to ±0.01 mm because of larger Young′s modulus of vitrified bond than resin bond. The grinding time of a PDC product can be 1.75–2.0 min from 3.25–3.5 min, so this kind of grinding wheel can save much time for processing PDCs. Also, there is hardly noise when using this new vitrified bond diamond grinding wheel to process PDCs. The amount of vitrified bond in grinding wheel influences the longevity of grinding wheel. When the size of diamond grains is 90–107 ¹m, the optimal amount of vitrified bond in grinding wheel is 21% (wt pct). When the amount of vitrified bond exceeds 21%, there are many pores in grinding block, which will decrease the longevity of grinding wheel. The existence of addition stuff such as Al2O3 or SiC can reduce the longevity of grinding wheel.
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    Microstructure Characterization of Long W Core SiC Fiber
    Changyou GUO, Caibei ZHANG, Lianlong HE, Baohong JIN, Nanlin SHI
    J. Mater. Sci. Technol., 2007, 23 (05): 677-684. 
    Abstract   HTML   PDF (3581KB)
    Microstructure of SiC fiber manufactured by chemical vapor deposition (CVD) onto tungsten (W) wire core was investigated by analytical electron microscopy (AEM). The results reveal that the fiber consists of W core, SiC sheath and C-coating. SiC sheath could be subdivided into two parts according to whether containing C rich stripe, or not. An emphasis was put on W/SiC interfacial reaction products and the transition zone between sub-layers in SiC sheath. The W/SiC interface consists of three layers of reaction production, namely, W2C, W5Si3 and WC. And there are amounts of facet faults existing in (100) face of WC crystalline and two classes of stack faults in WC have been revealed. The formation essence of different sublayers in SiC sheath was also discussed.
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    Effective Increase of Crystal Area during Sublimation Growth of 6H-SiC by Using the Cone-shaped Baffle
    Shouzhen JIANG, Xiangang XU, Xiaobo HU, Juan LI, Xiufang CHEN, Minhua JIANG
    J. Mater. Sci. Technol., 2007, 23 (05): 685-688. 
    Abstract   HTML   PDF (770KB)
    A novel design of crucible is proposed in this paper for the growth of SiC crystals. The relation between grown crystal shape and temperature distribution in a growth chamber was discussed. It is pointed out that the crystal shape had a close relationship with temperature distribution. The calculations suggested that the radial temperature field of the growing crystal became homogenous by setting up the cone-shaped baffle in the growth chamber. By modifying the crucible design and temperature distribution in the growth chamber, it is possible to enhance the enlargement of crystal, and also possible to keep grown surface flat.
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    Individual Grain Orientation and Heterogeneous Deformation in Cold-deformed Interstitial-Free Sheet Steel
    Y, ong LIU, Chungang WANG, Qiwu JIANG, Tong HE, Liang ZUO
    J. Mater. Sci. Technol., 2007, 23 (05): 689-692. 
    Abstract   HTML   PDF (1913KB)
    The cold rolling deformation textural evolution of an interstitial-free (IF) steel sheet is investigated by experiment and simulation. The microstructure of the IF steel is observed by transmission electron microscopy (TEM). The relationship between the deformation behavior of individual grain and the grain orientation are connected by Taylor factor M. The results show that the grains with higher Taylor factor are deformed slighter than those with lower ones. By considering the heterogeneous deformation, the texture simulation result can be greatly improved.
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    Crystallization Behaviour and Mechanical Properties of Zr65Cu18Ni9Al8 Bulk Metallic Glass
    M.Iqbal, J.I.Akhter, Haifeng ZHANG, Zhuangqi HU
    J. Mater. Sci. Technol., 2007, 23 (05): 693-696. 
    Abstract   HTML   PDF (444KB)
    Designing and synthesis of cost effective bulk metallic glasses (BMGs) has been of considerable interest during the last decade so that they can be made commercially viable. Among these, Zr-based BMGs have been reported extensively due to their attractive properties. An alloy having composition Zr65Cu18Ni9Al8 was designed and synthesized using 2–3 N pure materials by Cu mould casting. The alloy was characterized by Xray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and high temperature differential scanning calorimetry (DSC). Thermal parameters like supercooled liquid region △Tx, reduced glass transition temperature Trg, γ and δ parameters were evaluated. Mechanical properties like microhardness, nanohardness, elastic modulus and fracture strength were measured. The alloy showed wide supercooled liquid region of 129±1 K with improved thermal stability. The alloy has considerable fracture strength along with fair amount of ductility.
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    Influence of Zn2+ or Cu2+ on Reduction and Recalcination Behavior of Fe2TiO5
    M.Bahgat, M.H.Khedr, H.S.Abdelmaksoud
    J. Mater. Sci. Technol., 2007, 23 (05): 697-702. 
    Abstract   HTML   PDF (2837KB)
    Fe2O3, TiO2, CuO and ZnO powders were mixed according to the formula of (1-x)TiO2 xCuO-Fe2O3 or (1-x)TiO2 xZnO-Fe2O3 (x=0, 0.2 0.4, 0.6, 0.8, 1), and well ball-milled with H2O for 3 h to ensure homogeneity of the powdered solids, then fired at 1200℃ for 4 h. The fired samples were reduced at 500℃ with hydrogen gas. The reduced samples were subjected to recalcination at 500℃ in CO2 atmosphere. Both of fired, reduced and calcined samples were characterized by X-ray diffraction, vibrating sample magnetometry, reflected light microscopy and scanning electron microscopy. Different phases were formed after firing of Cu+2 or Zn2+ substituted Fe2TiO5. Magnetization (Bs) of the formed phases after firing are very low corresponding to diluted magnetic semiconductors (DMS) and increases with increasing the substituted cations (Cu+2 or Zn2+). The reduction of the fired samples enhanced the Bs values whereas the reducibility increases with increasing the Cu+2 or Zn2+ content. Samples show different tendency toward CO2 decomposition which is very important for environmental minimization for CO2.
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    Influence of Small Cr Addition on the Thermal Stability and Magnetic Properties of Fe-Co-Zr-Nb-B Glassy Alloys
    Min XU, Minxiu QUAN, Zhuangqi HU, Y, ong WANG, Liang ZUO
    J. Mater. Sci. Technol., 2007, 23 (05): 703-706. 
    Abstract   HTML   PDF (3414KB)
    Fe62Co8-xCrxZr6Nb4B20(x=0–4 at. pct) metallic glasses show high thermal stability with a maximum supercooled liquid region of about 84.8 K. The addition of 2 at. pct Cr causes the extension of the supercooled liquid region remarkably, leading to the enhancement of thermal stability and glass-forming ability. The crystallization of the Fe-based glassy alloys takes place through a single exothermic reaction, accompanying the precipitation of more than three kinds of crystallized phases such as α-Fe, Fe2Zr and ZrB2. The long-range atomic rearrangements required for the precipitation of the multiple crystalline phases seem to play an important role in the appearance of the large supercooled liquid region through the retardation of the crystallization reactions. The Fe-based alloys exhibit soft ferromagnetic properties. The saturation magnetization decreases with increasing Cr content while the saturated magnetostriction increases as a function of Cr content. There is no distinct change in the saturation magnetization and coercive force with annealing temperature below the crystallization temperature. The devitrification gives rise to a considerable enhancement in both δs and Hc.
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    A Reverse Numerical Approach to Determine Elastic-plastic Properties of Multi-layer Material Systems with Flat Cylindrical Indenters
    Baoxing XU, Zufeng YUE
    J. Mater. Sci. Technol., 2007, 23 (05): 707-712. 
    Abstract   HTML   PDF (950KB)
    In the present study, the indentation testing with a flat cylindrical indenter on typical multi-layer material systems was simulated successfully by finite element method. The emphasis was put on the methods of extracting the yield stresses and strain-hardening modulus of upper and middle-layers of three-layer material systems from the indentation testing. The slope of the indentation depth to the applied indentation stress curve was found to have a turning point, which can be used to determine the yield stress of the upper-layer. Then, a different method was also presented to determine the yield stress of the middle-layer. This method was based on a set of assumed applied indentation stresses which were to be intersected by the experimental results in order to meet the requirement of having the experimental indentation depth. At last, a reverse numerical algorithm was explored to determine the yield stresses of upper and middle-layers simultaneously by using the indentation testing with two different size indenters. This method assumed two ranges of yield stresses to simulate the indentation behavior. The experimental depth behavior was used to intersect the simulated indentation behavior. And the intersection corresponded to the values of yield stresses of upper and middle-layers. This method was also used further to determine the strain-hardening modulus of upper and middle-layers simultaneously.
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    Effect of Electron Beam Orientation on Exit Wave Function via Simulation of Electron Dynamic Diffraction
    Yanguo WANG, Hongrong LIU, Canying CAI, Qibing YANG
    J. Mater. Sci. Technol., 2007, 23 (05): 713-716. 
    Abstract   HTML   PDF (336KB)
    Based on the electron dynamic diffraction, phase shift of the exit wave function vs misorientation of the incident electron beam from the exact zone axis has been calculated for the [001] oriented copper. The result shows that the peak of phase shift is the maximum at the atom position as the electron beam along the exact [001] zone axis, and the peak value of phase shift decreases as increases of the misorientation. At small misorientation, i:e. less than 5 degree, change of the phase shift is minimal. The peak value of phase shift decreases significantly when the incident beam deviates form the zone axis over 10 degree and the exit wave has a planar configuration as the misoriention angle arrives ~17 degree. The effect of this phase shift characteristics on the information extracted from the hologram has also been considered.
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    Synthesis of Macroscopic Zr(C6H5PO3)2 Tubes
    Yuan YUAN, Jianjun YI, Chenglin MA, Qinghong XU
    J. Mater. Sci. Technol., 2007, 23 (05): 717-720. 
    Abstract   HTML   PDF (1030KB)
    A new method of infiltration-diffusion is used to synthesize macroscopic α-Zr(C6H5PO3)2 (α-ZrBP) tube. Compared to the routine method, no HF was used and a fiberlike product with several millimeters in length was obtained. SEM (scanning electronic microscopy) result indicates that these fibers are tubes. The wall of the tubes is composed of the flake of α-ZrBP overlapped with each other. As we know, it is the first report on the synthesis of millimeter-scale supramolecular assembly of α-ZrBP.
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ISSN: 1005-0302
CN: 21-1315/TG
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