Started in 1985 Semimonthly
ISSN 1005-0302
CN 21-1315/TG
Impact factor:6.155

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 2004, Volume 20 Issue 05 Previous Issue    Next Issue
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    Research Articles
    Quantitative Analysis of Zero and High Order Laue Zones Effects on the Exit Wave Function
    Canying CAI, Qibin YANG, Hongrong LIU, Yanguo WANG
    J. Mater. Sci. Technol., 2004, 20 (05): 481-484. 
    Abstract   HTML   PDF (1040KB)
    The exit wave function including zero and high order Laue zones has been simulated by both multi-slice method and electron dynamic diffraction analytical expression. Coincidence of the simulations by these two methods was achieved. The calculated results showed that the exit wave function highly dominated by zero order Laue zone, while high order ones modify the exit wave function to some extent depending on the situation. High order Laue zone effects become important for the following cases: sample consists of light elements, the thickness is very thin, lattice planar spacing perpendicular to the direction of the incident beam is large, and the electron beam has long wavelength. In these cases the exit wave function should be corrected by adding high order Laue zone effects. The analytical expression is effective and convenient for dealing with high order Laue zone effects.
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    Raman Scattering and t-Phase Lattice Vibration of 3% (mole fraction) Y2O3-ZrO2
    Xinglun TANG, Xiuhua ZHENG
    J. Mater. Sci. Technol., 2004, 20 (05): 485-489. 
    Abstract   HTML   PDF (644KB)
    The Raman spectra of 3% (mole fraction) Y2O3-ZrO2 (3Y) are obtained at different temperature from 77 K to 853 K. The results show that 260 cm-1 Eg and 460 cm-1 Eg modes on the spectra shift toward lower wave number with the increase of temperature; meanwhile, the continuity of the Half Width at Half Maximum (HWHM) and wave number (frequency) of Raman bands are broken and t-phase only partially transforms to m-phase at 523 K. Based on the experimental results, this paper discusses the t-phase lattice vibration of 3Y and presents the images of vibration displacement of six Raman-active modes for t-phase of ZrO2. The analysis indicates that there are diversities existing in the displacement of the atomic vibration of Raman-active modes because of their different symmetries at various temperature, which leads to the different change tendencies of Raman bands. Furthermore, the abrupt changes of some Raman-active modes indicating the atomic displacement are assumed to be the condensations of phonon modes in the t→m phase transition.
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    New Developments in Structural Health Monitoring Based on Diagnostic Lamb Wave
    Shenfang YUAN, Yingdi XU, Ge PENG
    J. Mater. Sci. Technol., 2004, 20 (05): 490-496. 
    Abstract   HTML   PDF (1518KB)
    Structure health monitoring based on diagnostic Lamb waves has been found to be one of the most promising techniques recently. This paper has a brief review of the new developments on this method including the basic novel of the method, fundamentals and mathematics of Lamb wave propagation, narrowband and wideband Lamb wave excitation methods, optimization of excitation factors and diagnostic Lamb wave interpretation methods.
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    Computer Simulation of Ferrite Transformation during Hot Working of Low Carbon Steel
    Yunbo XU, Yongmei YU, Xianghua LIU, Guodong WANG
    J. Mater. Sci. Technol., 2004, 20 (05): 497-500. 
    Abstract   HTML   PDF (437KB)
    On the basis of transformation kinetics and thermodynamics, the austenite-ferrite transformation start temperature during deformation was predicted for several grades of low-carbon steels under different processing conditions. Results indicate that Ar3d temperature mostly depended on alloying composition and processing parameters. Ar3d increased as strain rate or strain increased for the same steel grade. In view of enhancement of deformation on transformation, the basic kinetics model was established to simulate deformation induced transformation behavior, using which the influence of the deformation stored energy and effective deformation ledge on the nucleation and growth can be considered. The simulated results are in good agreement with experiment results.
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    Modelling of Microstructural Evolution and Prediction of Mechanical Properties of Plain Carbon Strip Steel in Hot Rolling Process
    Xiaochun SHA, Chunli MO, Dianzhong LI, Yiyi LI
    J. Mater. Sci. Technol., 2004, 20 (05): 501-505. 
    Abstract   HTML   PDF (515KB)
    Based on hot rolling production line of strip steel, the off-line in-house software, termed as ROLLAN (Rolling Analysis), is developed. The code is mainly used to predict the evolution of temperature, rolling force, fraction and grain size of recrystallization, fraction and grain size of phase transformation and final mechanical properties. Almost all the processing parameters affecting microstructure and mechanical properties in the schedule from reheating to the coiling process are considered in detail. Self-learning coefficient is adopted to adjust the deviation between predicted and measured temperatures, such as roughing exit temperature (RT2), finishing exit temperature (FT7) and coiling temperature (CT). Due to the application of low-speed-threading, increasing-speed-rolling and decreasing-speed-delivery process during finishing rolling and different cooling condition, after coiling the thermal-mechanical history of different position, along strip longitudinal direction is different resulting in inhomogeneous mechanical properties. So the segments are divided along longitudinal direction to identify the variation of microstructure and mechanical properties. An example of plain carbon strip steel Q235 with various thickness is used to compare the calculated mechanical properties with measured ones. For the specific grade of Q235 , the maximum deviation of tensile strength is less than 10.3 MPa, the yield strength is less than 13.2 MPa, and elongation is less than 1.99%. Further work will focus on the on-line application and consider the effect of macrosegregation and sulfur content of cast slab.
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    Growth and Solvent Effects of a Promising Nonlinear Optical Sodium Paranitrophenolate Dihydrate (NO2-C6H4-ONa∙2H2O) Single Crystal
    B.Milton Boaz, A.Leyo Rajesh, S.Xavier Jesu Raja, S.Jerome Das
    J. Mater. Sci. Technol., 2004, 20 (05): 505-508. 
    Abstract   HTML   PDF (347KB)
    Sodium paranitrophenolate dihydrate (NPNa∙2H2O) is an excellent semiorganic nonlinear optical (NLO) material, crystallizes both in water and methanol with high degree of transparency. Good optical quality single crystals of dimension upto 18 mm×6 mm×3 mm are obtained by sothermal solvent evaporation technique. The solubility of the crystal in different solvents was measured gravimetrically. The single crystals of NPNa∙2H2O show variation in physical properties and growth rate in different solvents. Methanol or ethanol solution yields crystals of bipyramidal shape with clear morphology. However, methanol grown crystal is exhibiting improved hardness parameters and possesses excellent thermal stability as compared to water grown crystals. The effects of solvent on hardness parameter along with thermal and optical properties of NPNa∙2H2O was revealed in this paper.
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    Effect of Initialization Technical Parameters on Optical Absorption of Ge2Sb2Te5 Thin Films
    Ming FANG, Qinghui LI, Fuxi GAN
    J. Mater. Sci. Technol., 2004, 20 (05): 509-511. 
    Abstract   HTML   PDF (433KB)
    The optical absorption properties of phase-change optical recording thin films subjected to various initialization conditions were investigated. The effects of initialization power and velocity on optical constants of the Ge2Sb2Te5 thin films were also studied. The energy gap of Ge2Sb2Te5 thin films subjected to various initialization conditions was also obtained. It was found that the optical energy gap of the Ge2Sb2Te5 thin films increased with either increasing initialization laser power or decreasing initialization velocity, with peak of 0.908 eV at laser power of 1000 mW or initialization velocity of 4.0 m/s, but the continued increasing initialization laser power or decreasing initialization velocity resulted in the decrease of the optical energy gap. The change of the optical energy gap was discussed on the basis of amorphous crystalline transformation.
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    Theoretical Studies on the SAW Properties of LGS at High-Temperature in Optimal Cuts
    Xiaojun JI, Tao HAN, Wenkang SHI, Guowei ZHANG
    J. Mater. Sci. Technol., 2004, 20 (05): 512-516. 
    Abstract   HTML   PDF (921KB)
    Surface acoustic wave (SAW) devices play a significant role in signal processing, frequency control and sensing applications. In general, they cannot operate at elevated temperature. The new crystal of langasite provides possibility for surface acoustic wave devices applied at high temperature. This paper studies the SAW properties of single and doubly rotated cuts of LGS at high temperature. The calculated SAW properties of LGS are analyzed in space with aid of contour plots, and two promising SAW orientation regions at high temperature are presented. For some typical cuts and propagating directions within the two optimal regions, their SAW characteristics vs temperatures are discussed. Based on the experimental evidence in some literatures, the reliability of calculated results is verified.
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    Luminescence of Eu2+ in Barium Octoborat
    Yushan XIE, Shengling ZHANG, Qinghua ZENG, Zhiwu PEI, Qiang SU
    J. Mater. Sci. Technol., 2004, 20 (05): 517-522. 
    Abstract   HTML   PDF (308KB)
    The luminescences of Eu2+ in low- and high-temperature modified BaB8O13 are reported. The valance change from Eu3+ to Eu2+ is observed when the samples are prepared in air. Eu2+ shows f-d transition at room temperature under UV excitation. The temperature dependency of the emission of Eu2+ in the hosts is studied. Multiple crystallographic sites for Eu2+ in the lattice are observed.
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    Polybutylacrylate/poly(methyl methacrylate) Core-Shell Elastic Particles as Epoxy Resin Toughener: Part I Design and Preparation
    Jianli WANG, Myonghoon LEE, Xiaomei YU, Jianbin JI, Kejian YAO
    J. Mater. Sci. Technol., 2004, 20 (05): 522-526. 
    Abstract   HTML   PDF (400KB)
    Polybutylacrylate (PBA)/poly(methyl methacrylate) (PMMA) core-shell elastic particles (CSEP), whose rubbery core diameter ranged from 0.08 μm to 1.38μm, were synthesized by using conventional emulsion polymerization, multi-step emulsion polymerization, and soapless polymerization. Allyl methacylate (ALMA) and ethylene glycol dimethacrylate (EGDMA) were selected as crosslinking reagents for core polymerization. Methacrylic acid (MAA) was used as functional co-monomer with methyl methacrylate as shell component. The content of vinyl groups in PBA rubbery core increased with the amount of crosslinking reagents. The core-shell ratio affected great on the morphology of the complex particles. Furthermore, the amounts of carboxyl on the surface of core-shell particles, copolymerized with acrylic acid, were determined by potentiometric titration. Results showed that methylacrylic acid was distributed mostly on the surface of particles.
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    Raman Spectrum and Thermal Stability of a Newly Developed TeO2-BaO-BaF2-La2O3-LaF3 Glass
    Junjie ZHANG, Shixun DAI, Shiqing XU, Guonian WANG, Liyan ZHANG, Lili HU
    J. Mater. Sci. Technol., 2004, 20 (05): 527-530. 
    Abstract   HTML   PDF (301KB)
    In this work, a new TeO2-BaO-BaF2-La2O3-LaF3 oxyfluorotellurite glass system is investigated. Differential thermal analysis (DTA) and structural analysis by Raman scattering spectra are reported on the glasses. The DTA results indicated that an increase of fluoride content in the glasses decreases the glass transition temperature (Tg) and increases the crystallization onset temperature (Tx). As a result the 70TeO2•20BaF2•10LaF3 glass showed a large Hruby's parameter, possessing excellent thermal stability. Changes in glass network structure with fluoride content are discussed based on the Raman scattering spectra of glasses. The glass network structures in the 70TeO2• (20-x)BaO•xBaF2• (10-y)La2O3•yLaF3 glasses are basically composed of both Te(O, F)4 and Te(O, F)3 units, but the Te(O, F)4/Te(O, F)3 ratio in the glass becomes higher with increasing fluoride content. This may be considered one of the reasons why the 70TeO2•20BaF2•10LaF3 glass exhibits excellent thermal stability.
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    Synthesis and Formation Mechanisms of Calcium Ferrite Compounds
    Hesham I.Saleh
    J. Mater. Sci. Technol., 2004, 20 (05): 530-534. 
    Abstract   HTML   PDF (374KB)
    Calcium ferrite compounds were prepared using calcium nitrate and iron nitrate with different molar ratios, 1:1, 0.5:1, and 1:0.5, respectively. The reactions of formation were investigated at different temperatures following the differential thermal analysis (DTA) results. Calcium ferrite compounds are CaFeO3, Ca2FeO3.5, Ca2Fe2O5, CaFe2O4, CaFe4O7, Ca7.2F0.8Fe30O53, Ca3Fe15O25, Ca4Fe14O25, and Ca4Fe9O17. Other reactive species of calcium nitrate are still present after firing at 450ºC. Compounds were characterized using X-ray diffraction (XRD), DTA, TG, magnetic susceptibility, infrared spectra and scanning electron microscope (SEM). It is concluded that the formation mechanism of Ca-ferrite compounds depends mainly on the valency of iron cations which in role depends on its molar ratio and the existing atmosphere.
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    A Macroscopic Model for the Portevin-Le Chatelier Effect
    Zhongjia CHEN, Qingchuan ZHANG, Zhenyu JIANG, Huifeng JIANG, Xiaoping WU
    J. Mater. Sci. Technol., 2004, 20 (05): 535-539. 
    Abstract   HTML   PDF (350KB)
    The Portevin-Le Chatelier (PLC) effect means serrated yielding or jerky flow phenomenon in some alloys. In this paper a macroscopic model is developed to investigate the PLC effect with the emphasis on mechanical response of the structure evolution on microscopic scale. In addition to the normal work hardening effect, the model takes account of the thermal activation of dislocation moving with the aid of stress and the collective interactions between mobile dislocations and solute atoms due to dynamic strain ageing (DSA). It can satisfy the negative strain rate sensitivity of flow stress, which is believed to be one of the most special features associated with the PLC effect. The heterogeneous nature of the deformed material is also considered by introducing a nonuniform spatial distribution of some model parameters. The serrated yielding and localized deformation behavior can be successfully reproduced via numerical simulation based on this model.
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    Effect of Some Heterocyclic Derivatives on the Removal of Copper Ions from Wastewater by Cementation
    A.A.Taha, M.G.Marei, D.E.Abd El-khalek
    J. Mater. Sci. Technol., 2004, 20 (05): 539-546. 
    Abstract   HTML   PDF (743KB)
    Removal of copper ions from copper sulphate solutions on a rotating zinc rod in absence and in presence of 3(2H)-furanones and 4H-pyran-4-one derivatives was investigated experimentally. Variables studied were initial copper ions concentration, rotational speed of the zinc rod, temperature and concentration of organic additives. It was found that cementation reaction is first order in presence and in absence of additives. Increasing concentration of initial copper ions, rotational speed of the zinc rod and temperature were found to increase the rate of cementation. In presence of organic additives an enhancement of the rate was observed, except in presence of methoxyfuranone the rate was found to decrease by an amount ranging from 11.74% to 33.79%. Rate acceleration or inhibition is associated mainly with changes in the structure of the additives as well as its concentration. The apparent activation energy for the cementation process in presence of different additives was estimated and was found to be ranged between 11.8 kJ/mol and 25.95 kJ/mol. These values suggest that the copper removal process in presence of these additives is controlled by diffusion. A scanning electron microscopy study of copper deposits obtained in presence of tolylfuranone, phenylpyrone and methoxyfuranone correlate with their behaviour during the kinetic study. Different reaction conditions and the physical properties of solutions were studied to obtain dimensionless correlation among all these parameters. It was found that on applying cementation reaction on a sample from industrial wastewater in presence of phenylpyrone about 91.9% of Cu2+ are removed.
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    Properties and Application of Nanocrystalline Poly (vinyl chloride)
    Chuanxi XIONG, Hong YANG, Lijie DONG, Qihong LIU, Qingmin LIU
    J. Mater. Sci. Technol., 2004, 20 (05): 547-550. 
    Abstract   HTML   PDF (346KB)
    The structure and properties of nanocrystalline PVC were investigated. The crystalline region of nanocrystalline PVC was observed by TEM to be 80 nm. The melting point of nanocrystalline PVC was found to be 128ºC which is obviously lower than typical PVC (210ºC). The X-ray diagram indicated that the crystal existed in nanocrystalline PVC. The evident effect of self-plasticizing and reinforcement appeared when nanocrystalline PVC was added. The optimum amount for self-plasticizing is about 10%. The maximal impact strength of 95.1 kJ/m2 was achieved by adding 20% nanocrystalline PVC and tensile strength with 56.2 MPa which was 122% of pure PVC was obtained after adding 5% nanocrystalline PVC.
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    Characterization of Sol-gel-derived TiO2 and TiO2-SiO2 Films for Biomedical Applications
    Jingxiao LIU, Fei SHI, Dazhi YANG
    J. Mater. Sci. Technol., 2004, 20 (05): 550-554. 
    Abstract   HTML   PDF (440KB)
    In order to improve the corrosion resistance and biocompatibility of NiTi surgical alloy, TiO2 and TiO2-SiO2 thin films were prepared by sol-gel method. The surface characteristics of the film, which include surface composition, microstructure and surface morphology, were studied by X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectra (XPS), respectively. A scratching test was used to assess the interface adhesive strength between the film and substrate. The corrosion resistances of NiTi alloy coated with oxide films were studied by anodic polarization curves measurement in biological solution. Additionally, a preliminary study of the in vitro bioactivity of the films was conducted. The results indicated that TiO2 and TiO2-SiO2 (Ti/Si=4:1) films have higher electrochemical corrosion resistance and can be used as protective layers on NiTi alloy. In addition, TiO2-SiO2 composite films have better bioactivity than TiO2 film.
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    Fullerenol-containing Materials Derived by Sol-gel Processing
    Haiping XIA, Zhaoyang JIANG, Jianli ZHANG, Jinhao WANG, Yuepin ZHANG, Qiuhua NIE
    J. Mater. Sci. Technol., 2004, 20 (05): 555-557. 
    Abstract   HTML   PDF (330KB)
    Water soluble fullerenols were synthesized and incorporated in SiO2, SiO2-TiO2, GPTMS- SiO2, GPTMS-ATPS inorganic and organic-inorganic materials by sol-gel processes. The maximum concentrations of C60 (OH) n and C70 (OH) n in the obtained SiO2 gels were estimated to be about 0.6% and 1.5% in weight, respectively. The characteristics of the UV/visible spectra of fullerenols in H2O and various gels were measured and compared. The thermal stability of fullerenols in gels was investigated with differential thermal analysis (DTA). The results indicate that the absorption features of fullerenols in solid gels are similar to those in H2O and the fullerenols in SiO2 are stable at 400ºC. The optical limiting effect of the fullerenols was investigated preliminarily.
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    Development of a New Kind of High Strength Spring Steel
    Dexiang XU, Zhongda YIN, Defu LIU
    J. Mater. Sci. Technol., 2004, 20 (05): 557-560. 
    Abstract   HTML   PDF (437KB)
    A new kind of high strength, high toughness and high plasticity spring steel has been developed. The strength, the reduction of area and the elongation of the steel are all higher than those of the steel 60Si2CrVA. The decarburization resistance and the sag resistance are also higher than those of the steel 60Si2CrVA. It has good hardenability, and is suitable for making springs with big cross section. The bogie springs made of this kind of steel have passed 2×106 cycles without broken under the conditions of maximum stress of 906 MPa and the minimum stress of 388 MPa.
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    A Mixed-control Mechanism Model of Proeutectoid Ferrite Growth under Non-equilibrium Interface Condition in Fe-C Alloys
    Ruiheng WU, Xueyu RUAN, Hongbing ZHANG, T.Y.Hsu
    J. Mater. Sci. Technol., 2004, 20 (05): 561-566. 
    Abstract   HTML   PDF (626KB)
    By combining the α/γ interface migration and the carbon diffusion at the interface in Fe-C alloys, a mathematical model is constructed to describe the mixed-control mechanism for proeutectoid ferrite formation from austenite. In this model, theα/γ interface is treated as non-equilibrium interface, i.e., the carbon concentration of austenite at γ/α interface is obtained through theoretical calculation, instead of that assumed as the local equilibrium concentration. For isothermal precipitation of ferrite in Fe-C alloys, the calculated results show that the rate of interface migration decreases monotonically during the whole process, while the rate of carbon diffusion from γ/αinterface into austenite increases to a peak value and then decreases. The process of ferrite growth may be considered as composed of three stages: the period of rapid growth, slow growth and finishing stage. The results also show that the carbon concentration of austenite at γ/αinterface could not reach the thermodynamic equilibrium value even at the last stage of ferrite growth.
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    Effect of Al on Microstructures and Mechanical Properties of the Ultrahigh Carbon Steels
    Huifen PENG, Baoqi WANG, Jianjun ZHANG, Xiaoyan SONG, Xiaoli MA, Nanju GU
    J. Mater. Sci. Technol., 2004, 20 (05): 567-570. 
    Abstract   HTML   PDF (386KB)
    In this research, we tried to find a simple processing method to break up the network carbides in ultrahigh carbon steels (UHCS). Our results revealed that Al addition was favorable to the decrease in the proeutectoid carbides, the pearlite-colony size and the pearlitic interlamellar spacing of the forged microstructures, and that a fully-pearlitic structure was obtained in the UHCS containing 1.6 wt pct Al. The quenching-and-tempering process resulted in fine microstructure in those steels. On the other hand, the strength of the UHCSs increased with the increase of the Al content, and the highest strength was obtained at the UHCS with 1.6 wt pct Al. The UHCSs with Al contents higher than 1.3 wt pct showed a high tensile strength of more than σ b=1000 MPa and good ductility of higher than δ5=10% at ambient temperature.
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    Nickel-free Stainless Steel for Medical Applications
    Yibin REN, Ke YANG, Bingchun ZHANG, Yaqing WANG, Yong LIANG
    J. Mater. Sci. Technol., 2004, 20 (05): 571-573. 
    Abstract   HTML   PDF (405KB)
    BIOSS4 steel is essentially a nickel-free austenitic stainless steel developed by the Institute of Metal Research, Chinese Academy of Sciences, in response to nickel allergy problems associated with nickel-containing stainless steels that are widely used in medical applications. The high nitrogen content of this steel effectively maintains the austenitic stability and also contributes to the high levels of corrosion resistance and strength. BIOSS4 steel possesses a good combination of high strength and toughness, better corrosion resistance, and better blood compatibility, in comparison with the medical 316L stainless steel. Potential applications of BIOSS4 steel can include medical implantation material and orthodontic or orthopedic devices, as well as jewelries and other decorations.
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    Optimal Selection and Control for Precipitation of α2 Phase in Near α High Temperature Ti Alloys during Aging Treatment
    Jun ZHANG, Qingjiang WANG, Yuyin LIU, Li LI, Dong LI
    J. Mater. Sci. Technol., 2004, 20 (05): 574-576. 
    Abstract   HTML   PDF (278KB)
    The characteristic of the precipitation and growth of α2 ordered phase during aging treatment in near αTi alloys have been investigated in terms of the influences of aging temperature, aging time and aging manner. The results exhibit that aging temperatures influence the distribution ofα2 phase precipitated and cause the changes in growth speed ofα2 phase. For various aging temperatures, the time to finish precipitation ofα2 phase is different. The facts that various distribution characteristics and growth speed ofα2 ordered phase are caused by changed aging condition imply optimal selection and control for precipitation ofα2 ordered phase reachable. Some discussions on adoptable aging steps are presented.
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    A New hcp Phase Formed in the Ni-Nb System during Ion-beam-assisted Deposition
    Bin ZHAO, Kuiwei GENG, Fei ZENG, Feng PAN
    J. Mater. Sci. Technol., 2004, 20 (05): 577-579. 
    Abstract   HTML   PDF (223KB)
    The Ni80Nb20 films were prepared by ion beam assisted deposition (IBAD) with various Ar+ ion energies. A phase evolution of fcc→amorphous→Ni+Nb→Ni+hcp was observed with the increasing of ion beam energy from 2 keV to 8 keV. When bombarded by Ar+ ions of 8 keV during deposition, a new crystalline phase with hcp structure was obtained, of which the lattice parameters are a=0.286 nm and c=0.483 nm, different from those of the similar A3B-type hcp phase previously reported. The experimental results were discussed in terms of thermodynamics and restricted kinetic conditions in the far-from-equilibrium process of IBAD. The formation of hcp phase may also be related to the valence electron effect.
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    Rheological Behavior of Semi-Solid AZ91D Alloy
    Weimin MAO, Zisheng ZHEN, Shijian YAN, Xueyou ZHONG
    J. Mater. Sci. Technol., 2004, 20 (05): 580-582. 
    Abstract   HTML   PDF (356KB)
    The rheological behavior and microstructure of semi-solid AZ91D was studied using a Couette type viscometer. The results show that the apparent viscosity of semi-solid AZ91D increases with the cooling rate increasing when it is continuously cooled and mechanically stirred and the empiric relation of the apparent viscosity with the cooling rate and solid fraction at shearing rate 93.7 s-1 is expressed as η=[0.66-0.63e(-ε3.01)]e (fs/0.14), and with the shearing rate and solid fraction at cooling rate 4ºC/min is shown as η=0.55e(fs/0.11- /87.59), as well as the cooling rate and shearing rate have an important effect on the microstructure of the semi-solid AZ91D alloy slurry, and decreasing the cooling rate and increasing the shearing rate are favorable to the nondendritic evolution of the primary grains.
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    Formation of Nanoscale Intermetallic Phases in Ni Surface Layer at High Intensity Implantation of Al Ions
    I.A.Bozhko, S.V.Fortuna, I.A.Kurzina, I.B.Stepanov, E.V.Kozlov, Yu.P.Sharkeev
    J. Mater. Sci. Technol., 2004, 20 (05): 583-586. 
    Abstract   HTML   PDF (359KB)
    The results of experimental study of nanoscale intermetallic formation in surface layer of a metal target at ion implantation are presented. To increase the thickness of the ion implanted surface layer the high intensive ion implantation is used. Compared with the ordinary ion implantation, the high intensive ion implantation allows a much thicker modified surface layer. Pure polycrystalline nickel was chosen as a target. Nickel samples were irradiated with Al ions on the vacuum-arc ion beam and plasma flow source "Raduga-5". It was shown that at the high intensity ion implantation the fine dispersed particles of Ni3Al, NiAl intermetallic compounds and solid solution Al in Ni are formed in the nickel surface layer of 200 nm and thicker. The formation of phases takes place in complete correspondence with the Ni-Al phase diagram.
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    Study on Modification Mechanism of Rare Earth in ZA27 Cast Alloy with Electronic Theory and Molecular Dynamics Method
    Guili LIU, Rongde LI, Zhenping ZHOU
    J. Mater. Sci. Technol., 2004, 20 (05): 586-588. 
    Abstract   HTML   PDF (191KB)
    A model of liquid ZA27 cast alloy is established according to molecular dynamics theory and an atomic structural model of co-existent α phase and liquid is also presented by means of computer programming. Recursion method is adopted to calculate the electronic structure of RE (rare earth) in grains and around phase boundaries respectively. The calculation shows that RE is more stable around phase boundaries than in grains, which explains the fact that the solution of RE inα phase is less, and RE mainly aggregates in front of phase boundary. The calculations of bonding order integrals also show that RE in front of phases hardly solidify onto the grain surfaces as active element so as to prevent grains growth and refine the grains. As a result, the modification mechanism of RE may be explained from the view of electronic structure.
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    Massive Si Phase and Its Growth Mechanism in Al-Si Casting Alloy
    Hengcheng LIAO, Guoxiong SUN
    J. Mater. Sci. Technol., 2004, 20 (05): 589-591. 
    Abstract   HTML   PDF (1739KB)
    Optical microscope and scanning electron microscope were used to observe the microstructure of the Al-11.6%Si and Al-11.6%Si-0.4%Mg alloys and the morphology of the massive silicon particles. It is found that the massive silicon phase, observed in the unfully modified alloys with 0.010%Sr, disappears completely in the alloys fully modified with 0.020%Sr. The serrations and reentrant edges shown in the massive silicon particles with the conventional casting indicate that the TPRE mechanism plays an important role in the growth of the massive silicon phase. The ripples and steps suggest that the "lateral microscopic growth" may be another operating mechanism.
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    Effect of Heating Rates on the Formable Oxide Scale on a C-Steel Surface
    J. Mater. Sci. Technol., 2004, 20 (05): 591-594. 
    Abstract   HTML   PDF (760KB)
    Oxide scale formation on a C-steel surface has been investigated using linear heating rates ranging from 0.1ºC/min to 10ºC/min at high temperatures. The studies on the oxide scale formation at high temperature (650ºC) at slower heating rate (0.1ºC/min) shows that the kinetic regime is linear. X-ray diffraction measurements revealed that the scale constituents are significantly influenced by the heating rate. The adherence of the scale was improved by using slower heating rate (0.1ºC/min-≤650ºC), while above such degree the scale was susceptible to cracking and flaking out of the alloy surface. In fact, the development of oxide growth stresses can cause considerable scale cracking. As well, variation of the crystallite sizes under the aforementioned conditions might affect the scale stacking to the alloy surface. The secondary electron detector images of the oxide scale shows that the scale was imperfectly smooth and there were a number of voids and defects in the scale skin, especially at fast heating rate. This observation could be attributed to defects of the as-received alloy. In general, slower heating rate reduced the defects of the scale and improved its adherence.
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    A Finite Difference Method for Determining Interdiffusivity of Aluminide Coating Formed on Superalloy
    Hua WEI, Xiaofeng SUN, Qi ZHENG, Guichen HOU, Hengrong GUAN, Zhuangqi HU
    J. Mater. Sci. Technol., 2004, 20 (05): 595-598. 
    Abstract   HTML   PDF (462KB)
    A numerical method has been developed to extract the composition-dependent interdiffusivity from the concentration profiles in the aluminide coating prepared by pack cementation. The procedure is based on the classic finite difference method (FDM). In order to simplify the model, effect of some alloying elements on interdiffusivity can be negligible. Calculated results indicate the interdiffusivity in aluminide coating strongly depends on the composition and give the formulas used to calculate interdiffusivity at 850, 950 and 1050ºC. The effect on interdiffusivity is briefly discussed.
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    Formation of TiO2 Modified Film on Carbon Steel
    Laizhou SONG, Shizhe SONG, Zhiming GAO
    J. Mater. Sci. Technol., 2004, 20 (05): 599-601. 
    Abstract   HTML   PDF (282KB)
    A new technique for preparing TiO2 modified film on carbon steel was accomplished by electroless plating and sol-gel composite process. The artificial neural network was applied to optimize the preparing condition of TiO2 modified film. The optimized condition for forming TiO2 modified film on carbon steel was that NiP plating for 50 min, dip-coating times as 4, heat treatment time for 2 h, and the molar ratio of complexing agent and Ti(OC4HZ9)4 kept 1.5:1. The results showed that TiO2 modified film have good corrosion resistance. The result conformed that it is feasible to design the preparing conditions of TiO2 modified film by artificial neural network.
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    Topological Transformation during Normal Grain Growth
    Chaogang LOU, Michael A.Player
    J. Mater. Sci. Technol., 2004, 20 (05): 601-604. 
    Abstract   HTML   PDF (312KB)
    This paper investigates topological transformation during normal grain growth by carrying out a computer vertex simulation. Results show that topological correlation agrees with the models proposed by Blanc et al and Weaire. Topological transformation occurs more often on grains with some topological classes instead of equal probability on each boundary. This can be qualitatively explained by topological correlation.
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    Characteristics of Deformation and Recovery in Ti50Ni47Fe3 Shape Memory Alloy
    Wei JIN, Ying YAN, Jian WANG, Mingzhou CAO, Rui YANG
    J. Mater. Sci. Technol., 2004, 20 (05): 605-608. 
    Abstract   HTML   PDF (604KB)
    The mechanical behavior and the effect of pre-strain on recovery behavior of Ti50Ni47Fe3 (at. pct) alloy were investigated systematically by tensile and recovered tests accompanied by electrical resistance measurement. Ti50Ni47Fe3 alloy has different deformation behaviors at different temperature ranges, the deformation curves in different temperature range can be classified into four kinds. The start temperature of recovery increases with the increase of pre-strain. There exists an optimal deformation condition, at which the specimen exhibits maximum free recovery strain. With increasing pre-strain the recovery stress increases and reaches the maximum at 8% pre-strain. R-phase to parent transition offered about 0.2% recovery strain. With pre-strain increasing the recovery stress increases and reaches to the maximum at 8% pre-strain. The recovery stress is corresponding with the critical stress of stress-induced martensitic transformation.
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    Miscibility, Thermal Stability, Rheological and Mechanical Properties of Blends Derived from Polysulfone Oligomer and Poly (phthalazinone ether sulfone ketone)
    Guimei WANG, Xigao JIAN, Gongxiong LIAO, Lihao WU
    J. Mater. Sci. Technol., 2004, 20 (05): 609-612. 
    Abstract   HTML   PDF (472KB)
    Poly (phthalazinone ether sulfone ketone) (PPESK) was melt blended with bisphenol-A polysulfone oligomer (O-PSF) to produce a thermoplastic polymer blends. The miscibility, thermal stability, rheological and mechanical properties of the blends were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and capillary rheometry. The blends showed single Tg over the composition range and possess homogeneous microstructure. The addition of O-PSF slightly affected the thermal properties of the blends. PSF oligomer, as a processing aid, could markedly improve the processability of the PPESK. In addition, the mechanical properties of the blends were increased, to some degree, by adding O-PSF.
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    Preparation of a Novel Micro/nano Tubes via Electrospun Fiber as a Template
    Taiqi LIU
    J. Mater. Sci. Technol., 2004, 20 (05): 613-616. 
    Abstract   HTML   PDF (435KB)
    Poly (para-xylylene) hollow fibers with inner diameters can be prepared via template fibers electrospun from solutions. The PPX is deposited from the vapor phase and the template fiber is selectively removed by heat treatment or solvent extraction. The PPX is partially crystalline and the crystal modification depending on the route is used to extract the template fiber. The thermal stability of the hollow fibers is only slightly reduced relative to the bulk material and the same holds for the UV-stability.
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    Adhesive Bonding and Self-Curing Characteristics of α-Starch Based Composite Binder for Green Sand Mould/Core
    Xia ZHOU, Jinzong YANG, Guohui QU
    J. Mater. Sci. Technol., 2004, 20 (05): 617-621. 
    Abstract   HTML   PDF (469KB)
    Interactions between different components in α-starch based composite binder for green sand mould/core were investigated by using XRD, IR spectra, 1H NMR spectra and SEM. Several adhesive hardening structures and theories of the binder at room temperature were proposed according to the interactions between various compositions. Thus, the reasons for the binder to have excellent combination properties and unique adhesive bonding and self-curing characteristics were explained by these theories successfully. And the theories are of great directive importance to design and development of composite binder for green sand mould/core.
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    Neuro-Knowledge-Based Expert System (NKBES) for Optimal Scheming of Die Casting Process
    Qiaodan HU, Peng LUO, Yi YANG, Liliang CHEN
    J. Mater. Sci. Technol., 2004, 20 (05): 622-626. 
    Abstract   HTML   PDF (267KB)
    We develop a neuro-knowledge-based expert system (NKBES) frame in this work. The system mainly concerns with decision of gating system and die casting machine based on a neuro-inference engine launched under the MATLAB software environment. For enhancement of reasoning agility, an error back-propagation neural network was applied. A rapidly convergent adaptive learning rate (ALR) and a momentum-based error back-propagation algorithm was used to conduct neuro-reasoning. The working effect of the system was compared to a conventional expert system that is based on a two-way (forward and backward) chaining inference mechanism. As the reference, the present paper provided the neural networks sum-squared error (SSE) and ALR vs iterative epoch curves of process planning case mentioned above. The study suggests that the neuro-modeling optimization application to die casting process design has good feasibility, and based on that a novel and effective intelligent expert system can be launched at low cost.
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    Hydroxyapatite-Bioglass-Titanium Biomaterials Used as Dense Bulk in Double-layer Biomimetic Composite
    Jianpeng ZOU, Jianming RUAN, Baiyun HUANG, Jianben LIU, Zhigang ZHAO
    J. Mater. Sci. Technol., 2004, 20 (05): 627-630. 
    Abstract   HTML   PDF (439KB)
    Sintering shrinkage, compressive strength, bending strength, chemical composition and their relationships with microstructure of HA-Ti and HA-BG-Ti biomaterials were studied. The results show that sintering shrinkage curve of HA-BG-Ti composite changes just like S shape (23.1%-16.2%-21.8%-17.1%) with increase of Ti content, and sintering shrinkage of HA-BG-Ti composite is always higher than that of HA-Ti composite. The approach also indicates that compressive strength and bending strength of HA-BG-Ti composite are always higher than that of HA-Ti composite. Basically, with its compressive strength and bending strength equaling to 211.5 MPa and 132.1 MPa respectively, HA-10 vol. pct BG-60 vol. pct Ti composite can meet the mechanical properties requirements of the outer dense bulk. Furthermore, microstructure analysis shows that interfacial integration of HA-BG-Ti composite is better than that of HA-Ti composite. From X-ray diffraction (XRD) and SEM-EDAX analysis, brittle new phases including calcium titanate and calcium carbonate are detected in HA-Ti composite. New phases in HA-Ti composite and complex strong binding force accompanied by elemental diffusion of Si, Ti in HA-BG-Ti composite can explain theoretically the great difference of mechanical properties of HA-Ti and HA-BG-Ti composites.
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    ZnSe/GaAs/Ge Triple Junction Solar Cell and Its Structure Design
    Aikun WANG, Guochang LI, Guoxiang ZHOU, Jertrude F.Neumark
    J. Mater. Sci. Technol., 2004, 20 (05): 631-633. 
    Abstract   HTML   PDF (332KB)
    A new method is given to increase doping concentration of p-type ZnSe up to 1×1018 cm-3 through adding a little Te. This method gets over the difficulty of the high doping concentration of p-type ZnSe for many years. The external quantum efficiency (QE) of ZnSe p-n junction solar cell has been measured, and ZnSe is a good material of the top cell in the tandem solar cells. The solar cells made from ZnSe/GaAs/Ge can cover 94% of the total solar spectrum under AM (air mass) 1.5, and their theoretical efficiency is 56%.
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    Improvement of Weld Quality Using a Weaving Beam in Laser Welding
    Xudong ZHANG, Wuzhu CHEN, Gang BAO, Lin ZHAO
    J. Mater. Sci. Technol., 2004, 20 (05): 633-636. 
    Abstract   HTML   PDF (576KB)
    This paper describes a way to improve the weld quality through suppressing the porosity formation and restraining the growth of columnar grains by using a weaving beam in laser welding. The experimental results show that the N2 porosity of beam-weaving laser welding low carbon steel can be remarkably reduced with increasing weaving frequency, and porosity can be eliminated when the weaving amplitude is only 0.5 mm; and the Ar porosity in the weld metal is decreased with increasing weaving frequency and amplitude when the welding speed is higher than 0.5 m/min. The beam-weaving laser welding of ultra-fine grained steel has been investigated. The experimental results show that beam-weaving laser welding with appropriate amplitude and frequency can partly restrain the growth of the columnar grain and improve the tensile strength of the weld metal.
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    Microwave Hydrothermal Synthesis PZT of Nanometer Crystal
    Hongxing LIU, Hong DENG, Yan LI, Yanrong LI
    J. Mater. Sci. Technol., 2004, 20 (05): 637-638. 
    Abstract   HTML   PDF (173KB)
    It was focused on the applications and developments of microwave hydrothermal synthesis piezoelectric ceramic powder. The microwave hydrothermal vessel was designed and manufactured. The microwave hydrothermal synthesis system was established and the PZT piezoelectric ceramic powder was synthesized. XRD and TEM have been used to characterize the products in detail. The diameter of the PZT powder particle is from 40 to 60 nm.
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    UV Spectral Analysis of the Chemical Modification and Photolysis of Acetylacetone Modified Alumina Aqueous Solution
    Chengbin JING, Xiujian ZHAO, Haizheng TAO, Xina WANG, Aiyun LIU
    J. Mater. Sci. Technol., 2004, 20 (05): 639-640. 
    Abstract   HTML   PDF (201KB)
    Acetylacetone was firstly introduced into the aqueous media with the presence of aluminum sec-butoxide and peptizator. It was confirmed that the UV (ultraviolet) absorption band of acetylacetone underwent 14 nm of red-shift due to the formation of the six-membered ring of the complex between alumina and acetylacetone in the aqueous solution. It was also found that the chemical modification can be dissociated by the UV irradiation with a wavelength shorter than 286 nm as a result of the excitation of π-π* transition in the complex.
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