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 October 2001, Volume 17 Issue S1 Previous Issue    Next Issue
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    Research Articles
    MEAM simulation of distribution of Nb atoms in TiAl plus Nb system
    Xiaodong NI, Guoliang CHEN, Xitao WANG, Xudong HUI
    J. Mater. Sci. Technol., 2001, 17 (S1): 1-7. 
    Abstract   HTML   PDF (1102KB)
    An accurate MEAM (modified embedded atom method) potential including angular dependence for TiAl compound has been developed. The properties of TiAl compound can be reproduced well. With this potential, the distribution of Nb atoms in L1(0) type TiAl compound with various composition are calculated by using an average-atom model similar to B-W (Bragg-Williams) method. The results of calculation showed that Nb atoms prefer to occupy the Ti sublattice of L10 structure, and with increasing atomic percent of Nb and Al, Nb atoms exhibited a trend of ordered distribution in Ti sublattice, and result in the formation of L1(0) derivative superlattice structure.
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    Finite element numerical simulation for influence of mold taper on thermomechanical behavior of steel billet in continuous casting process
    Engang WANG, Jicheng HE
    J. Mater. Sci. Technol., 2001, 17 (S1): 8-12. 
    Abstract   HTML   PDF (944KB)
    The thermomechanical behavior of the thin, growing shell during the early stages of solidification in the continuous casting mold is very important to the ultimate quality of the final billet. A two-dimensional, transient finite element model has been developed to treat the heat flow and deformation of solidifying shell in the continuous casting billet mold as coupled phenomena. The major application of the model is to predict the extent of the gap between the mold and the shell, and focus on the influence of mold taper on the thermomechanical behavior of the steel billet to help understand the formation of off-corner cracks and breakouts in the solidifying shell. The calculations indicate that the gap is initially formed at the corner of the billet, where heat transfer is greatly reduced. Insufficient mold taper contributes to a hot spot in the off-corner region, which corresponds to the thinnest shell thickness. Meanwhile, the solidifying front along the diagonal of the billet is subjected to an excessive mechanical strain, which causes the off-corner cracks and even the breakouts.
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    Atomistic simulation study of Zr segregation at the Ni3Al grain boundary
    Liping ZHENG, Shi QIU, Liping YU, Huyong ZHANG, Bingyao JING, Douxing LI
    J. Mater. Sci. Technol., 2001, 17 (S1): 13-16. 
    Abstract   HTML   PDF (674KB)
    The embedded atom method(EAM) is applied to calculate concentration distributions of Zr, Ni and Al at a Ni3Al-3 at. pct Zr grain boundary, and the Zr-induced distortion energies at the grain boundary, the bulk and the free surface. The calculated concentration distributions show that Zr segregation is present with Al-depletion and Ni-enrichment at the grain boundary. The reason might be that at the same zone, the Zr-induced distortion energy in the site of Al is always negative and lower than that of Ni, and that the Zr-induced distortion energy in the Al site at the grain boundary is the lowest among those at all zones.
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    Numerical simulation on process of hydrostatic extrusion for tungsten alloy through concave dies with equal-strain contour lines
    Zhaohui ZHANG, Fuchi WANG
    J. Mater. Sci. Technol., 2001, 17 (S1): 17-19. 
    Abstract   HTML   PDF (510KB)
    The numerical simulation to the process of hydrostatic extrusion for tungsten alloy through the concave dies with the equal-strain contour lines was carried out in this paper by the large deformation and elasto-plastic finite theory and ANSYS software. Both the pressure in the process of extrusion and the stress-strain distribution in the sample were analyzed, which founds a basis to the engineering application.
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    Thermo electrochemistry and its application to metallurgical research
    Zheng FANG, Quanru ZHANG, Hengzhong ZHANG, Yuan FANG
    J. Mater. Sci. Technol., 2001, 17 (S1): 20-24. 
    Abstract   HTML   PDF (963KB)
    The thermoelectrochemistry (TEC), a novel cross discipline, is presented, including the basic equations for a cell and a half-cell reaction, the treatment of experimental data and its application to electro-generative leaching of mineral and to measuring thermodynamic and kinetic data of an electrode reaction. The TEC technology will play an important part in the research on the metallurgical process under various fields.
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    EAM analysis of the lattice parameter effect in order-disorder transformation
    Timothee Nsongoa, Guoliang CHEN, Xiaodong NI
    J. Mater. Sci. Technol., 2001, 17 (S1): 25-30. 
    Abstract   HTML   PDF (907KB)
    The embedded atom method was used to theoretically analyze the effect of the lattice parameter variation on the order-disorder transformation in binary alloys. The simple model was considered in which the configuration energy E as function of the lattice parameter a and the long-range order parameter sigma was given by Taylor expansion at sigma =0. The following results were found for AB alloy, at T=0 K, the stable state exists in the completely ordered phase which was also found in the case of A(3)B or AB(3) compounds The order-disorder was found to be a second-order transition. Only one kind of order-disorder was found for AB alloy. Three groups of order-disorder transformation can be observed for the A(3)B or AB(3) compound. For the group I when the temperature is below the critical temperature, the order-disorder is a first order transformation. For the group II, the order-disorder transformation is a first order transition. For the group III, the order-disorder transformation is found to be a second order transition. The lattice parameter variations have a significant effect on E-2 coefficient, which is related to the ordering energy. These results are, in a good agreement with those obtained by using EAM (embedded atom method) and CVM (cluster variation method), calculations.
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    Microstructure and electrochemical characteristics of advanced composite Zr-based hydrogen storage alloy
    Mingfen WEN, Lian CHEN, Min TONG, Demin CHEN, Huiming CHENG, Yuchun ZHAI, Yanwen TIAN
    J. Mater. Sci. Technol., 2001, 17 (S1): 31-34. 
    Abstract   HTML   PDF (756KB)
    Zr0.9Ti0.1(Ni,Co,Mn,V)(2.1) as-cast alloy was prepared by melting under Ar atmosphere; and then, four composite alloys were prepared by ball-milling after hydrogen absorbing agent was added. The initial discharge capacity was as high as 430 mAh .g(-1) for composite alloy electrode c discharged at 60 mA .g(-1) current density and its maximum capacity reached 505 mAh .g(-1). All composite alloy electrodes have good activation behavior, being fully activated in one or two cycles. At 300 mA .g(-1) current density, the composite alloy electrode c was found to have good cycle stability.
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    Characterization of TiO2/TA(2)O(5) films synthesized by ion beam on NiTi alloy for biomedical applications
    Jingxiao LIU, Jihua CHEN, Dazhi YANG, Weiqiang WANG, Yinong WANG, Yingji CAI
    J. Mater. Sci. Technol., 2001, 17 (S1): 35-39. 
    Abstract   HTML   PDF (956KB)
    The biocompatibility of implants is determined by their corrosion resistance and surface characteristics. In this study, the surface composition, morphology and microstructure of TiO2/Ta2O5 films synthesized by ion beam enhanced deposition on NiTi alloy were studied. The scratch test results indicate that the interface adhesive strength of TiO2/Ta2O5 film increases with the increasing Ta content. The electrochemical corrosion measurement shows that the TiO2-36%Ta2O5 film is optimal for improving corrosion resistance of NiTi alloy.
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    Effect of annealing temperature on transformation behaviors of Ti-50.2 at. pct Ni thin film
    Xiaopeng LIU, Mingzhou CAO, Wei JIN, Changgong MENG, Dazhi YANG
    J. Mater. Sci. Technol., 2001, 17 (S1): 40-42. 
    Abstract   HTML   PDF (675KB)
    The effect of the annealing treatment on the transformation behaviors of the Ti-50.2 at. pct Ni thin films prepared,by d.c magnetron sputtering system was investigated, The results show that two different kinds of precipitates, both Ni3Ti and Ti4Ni2O, co-existed in the annealed thin films. The transformation temperatures of thin film increased with increasing annealing temperature from 500 to 650 degreesC, but they dropped at 750 degreesC. The complicated changes of the transformation temperatures were related to the existence of both Ni3Ti and Ti4Ni2O precipitates.
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    Study on the crystallization of amorphous Cr-Si-Ni thin films using in situ X-ray diffraction
    Xianping DONG, Jiansheng WU
    J. Mater. Sci. Technol., 2001, 17 (S1): 43-46. 
    Abstract   HTML   PDF (804KB)
    Crystallization behavior of amorphous Cr-Si-Ni thin films was investigated by means of high temperature in situ X-ray diffraction measurements. The diffraction spectra were recorded isothermally at temperature between 250 and 750 degreesC. The in situ testing of crystallization enables the direct observation of structure evolution which is dependent on heat treatment. Based on the testing results, the grain sizes of the crystalline phases were compared and phase transition tendency was understood. In the mean time, electrical properties of the films as functions of annealing temperature and time have been studied. The increase of volume fraction of CrSi2 crystalline phases in the Cr-Si-Ni films leads to the decrease in conductivity of the films. The annealing behavior of temperature coefficient of resistance (TCR) is a result of competition between a negative contribution caused by the weak localization effects in amorphous region and a positive contribution caused by CrSi2 grains. Thus the proper mixture of amorphous and crystalline constituents could result in a final zero TCR.
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    Effect of iron morphology and interfacial bonding on the toughening of Al2O3/Fe composites
    M.M.El-Sayed Seleman, Xudong SUN, Liang ZUO
    J. Mater. Sci. Technol., 2001, 17 (S1): 47-51. 
    Abstract   HTML   PDF (1302KB)
    Two morphologically different composites comprising an alumina matrix and 20 vol. pct Fe particles have been fabricated by hot pressing technique. Two kinds of microstructures, i.e. a dispersive distribution of Fe particles and a network distribution of Fe particles in alumina matrix, have been produced. Both composites are tougher than the virgin alumina matrix. The fracture toughness of the composite with a network microstructure is much higher than the composite with a microstructure of dispersed particles. For the particulate dispersion microstructure, the main limitation to the toughening is the lack of plastic deformation of the ductile Fe due to the pull out of Fe particles, indicating weak bonding at the Al2O3/Fe interface. For the network microstructure composite, the gauge length of the ductile phase is much larger, allowing the ductile Fe to be stretched to failure between the crack faces. The weak bonding at Al2O3/Fe interface can promote partial debonding and contribute further to toughening in the network microstructure composite.
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    Investigation on wear-resistant properties of Al2O3/SiC nano composite ceramics in fused zinc
    Yaling HAN, Quangang XIAN, Xibao WANG, Jialin LI, Yuqi JIANG, Yong LIANG
    J. Mater. Sci. Technol., 2001, 17 (S1): 52-56. 
    Abstract   HTML   PDF (1373KB)
    Al2O3/SiC nano composite ceramics can replace wear-resistant and heat-resistant alloys used in preparing the arm-bush that is the key parts in the equipment of galvanizing steel strip. Conventional alloy for arm-bush could only operate 4 similar to7 days, and the ceramic Arm-bush can operate more than 100 days continuously tested in the same equipment and its service life has increased 15 times more than that of alloy. According to the results of microstructure analysis, one of the most important cause that the composite ceramics possess excellent wear-resistant properties in the fused zinc is that nano SiC particles have existed within fine grains of Al2O3.
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    Optimization of electrical discharge machining characteristics of SiCp/LM25 Al composites using goal programming
    R.Karthikeyan, S.Raju, R.S.Naagarazan, B.C.Pai
    J. Mater. Sci. Technol., 2001, 17 (S1): 57-60. 
    Abstract   HTML   PDF (613KB)
    In the present study an effort has been made to optimize the machining conditions for electric discharge machining of LM25 Al (7 Si, 0.33 Mg, 0.3 Mn, 0.5 Fe, 0.1 Cu, 0.1 Ni,.2 Ti) reinforced with green bonded SiC particles with approximate size of 25 mum. Polynomial models were developed for the various EDM characteristics such as metal removal rate, tool wear rate and surface roughness in terms of the process parameters such as volume fraction of SK, current and pulse time. The models were used to optimize the EDM characteristics using nonlinear goal programming.
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    Effect of SiC particulates on the microstructure of Al-6Ti-6Nb matrix composites fabricated by mechanical alloying technique
    Dechang JIA, Qingchang MENG, Yu ZHOU, Tingquan LEI
    J. Mater. Sci. Technol., 2001, 17 (S1): 61-64. 
    Abstract   HTML   PDF (1033KB)
    Millimeter sized SiC (m-SiCp) and nanometer sized SiC (n-SiCp) particulates reinforced Al-6Ti-6Nb matrix composites were prepared by mechanical alloying (MA) and later hot-press sintering. Their microstructure was investigated to know the influence of the incorporated SiC particles. The secondary Al3Ti, AlNb2 intermetallics particle size, the Al matrix grain size and their submicrostructure are strongly affected, and they are correlated with the thermal stability of the composites.
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    Microstructure and mechanical properties of in-situ TiCp/2024 composite
    Mingzhen MA, Dayong CAI, Tianfu JING
    J. Mater. Sci. Technol., 2001, 17 (S1): 65-68. 
    Abstract   HTML   PDF (763KB)
    The microstructure of TiCp/2024 composite and the structure of interface between TiCp and Al are studied using SEM and TEM. The results show that the in-situ synthesized TiC particle has face-centered cubic structure (fcc). Meanwhile, particles are characterized as tiny and nearly globular. The orientation between TiC particles and Al matrix can be described as ((2) over bar(2) over bar0)(Al)//(02 (2) over bar)(Tic) and [(1) over bar 12](Al)//[011](TiC). Results of the mechanical property tests reveal that the ultimate strength (sigma (b)) and the yield strength (sigma (s)) of the composite are improved by 30% and 47% respectively, compared with the properties of 2024 matrix. In addition, the elongation (delta) value can still reach 4.3%. Thus TiCp/2024 composite has high comprehensive performance.
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    Self-similarity of the crack front in stress corrosion fracture
    Jie DENG, Qiyi LONG, Chiwei LUNG
    J. Mater. Sci. Technol., 2001, 17 (S1): 69-72. 
    Abstract   HTML   PDF (863KB)
    In this letter, a new method was proposed to visualize the crack front in stress corrosion fracture of high strength steel. The fractal characteristic of the crack front was analyzed by measuring its fractal dimension and roughness exponent at the same time. The experimental results show that the irregularity of the crack front was partly self-affine.
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    A new method of retarding fatigue crack growth on pressure vessels
    Jianzhong YIN, Yanyan WANG, Xinwei DING
    J. Mater. Sci. Technol., 2001, 17 (S1): 73-76. 
    Abstract   HTML   PDF (579KB)
    An artificial wedge to retard;fatigue crack growth in tension has been investigated. The results show that an artificial wedge can reduce the growth rate of fatigue crack on surface fatigue crack and, the fatigue crack growth behavior is essentially similar in-depth and width directions. Based on a theoretical analysis, a model for the effective crack growth parameter DeltaK(eff) is presented. It is shown that the relationship between the calculated DeltaK(eff) value and crack speed are almost the same as those of cracked specimens without a wedge. Therefore this model can be applied to estimate retardation behavior.
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    A fracture probability competition mechanism of stress corrosion cracking
    Yanliang HUANG
    J. Mater. Sci. Technol., 2001, 17 (S1): 77-80. 
    Abstract   HTML   PDF (756KB)
    The stress corrosion cracking (SCC) of austenitic stainless steel was studied via polarization, slow strain rate and scanning electron microscope (SEM) techniques. Many SCC mechanisms have been proposed in which hydrogen embrittlement and passive film rupture-repassivation theories are generally accepted, but they can hardly explain the SCC mechanism of austenitic stainless steel in acidic chloride solution adequately, because the steel is in active dissolution state and cathodic polarization can prevent it from occurring. Our experiment shows that the anodic current increases the creep rate and decreases the plastic strength of the material on single smooth specimen as well as at the SCC crack tip. The fractured surface was characterized as brittle cleavage, while the surface crack of smooth specimen was almost vertical to the tensile strength, which can confirm that the cracks were caused by tensile stresses. A fracture probability competition mechanism of SCC was proposed on the basis of the experimental results combined with the viewpoint of ductile-brittle fracture competition. When the anodic dissolution current is increased to a certain degree, the probability of fracture by tensile stress will exceed that by shear stress, and the brittle fracture will occur. The proposed SCC mechanism can riot only explain the-propagation of SCC cracks but can explain the crack initiation as well. The strain on the surface distributes unevenly when a smooth specimen is deformed, so does the anodic current distribution. The crack will initiate at a point where the anodic current density is large enough to cause the material at a specific point to fracture in brittle manner.
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    Effect of carbon and phosphorous on the solidification microstructure in a Cr-Ni-Mn-N austenitic hydrogen-resistant steel
    Jun TAN, Luming MA, Shouxin LI, Lijian RONG, Jincai YUAN, Yiyi LI
    J. Mater. Sci. Technol., 2001, 17 (S1): 81-84. 
    Abstract   HTML   PDF (1582KB)
    The influence of carbon and phosphorus on the solidification microstructure of a Cr-Ni-Mn-N austenitic steel was studied. The button specimens were prepared by vacuum induction melting and magnetic convection. The experimental results show that the increase of C or P concentration in the steel can change the solidification modes of Cr-Ni-Mn-N austenitic steels and has a significant effect on the morphology of the dendrites. The content of delta -ferrite in the microstructure reduces with increasing the concentration of C or P in the steel, there is a gradient of the content of delta -ferrite formed from surface through the center of the specimens.
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    Microhardness indentation size effect in flux-grown crystals of rare earth aluminates
    Jianghong GONG, Zhenduo GUAN
    J. Mater. Sci. Technol., 2001, 17 (S1): 85-88. 
    Abstract   HTML   PDF (730KB)
    The previously reported results of microhardness measurements on flux-grown crystals of rare earth aluminates were re-examined in this paper to explore the applicability of the proportional specimen resistance (PSR) model to describe the indentation size effect. It was found that the PSR model is insufficient for describing the experimental data and a modified form of this model was proposed based on the consideration of the effect of surface stress state on hardness testing.
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    Oxidation control and non-equilibrium phase formation in Cu-Cr alloys during mechanical alloying
    Xiaolong CUI, Lai WANG, Min QI
    J. Mater. Sci. Technol., 2001, 17 (S1): 89-92. 
    Abstract   HTML   PDF (751KB)
    Using X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimeter (DSC) and optical microscopy, phase transformation of Cu-Cr alloys with various compositions during mechanical alloying process has been investigated. Besides the formation of supersaturated solid solution, the results show that a kind of amorphous oxide formed in the process, and the addition of carbon has obviously effect on the suppression of oxidation and the deoxidization of oxide. The reactive milling has a remarkable effect on the behavior of oxidation.
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    Intergrain interaction, coercivity and Henkel plot for NdFeB magnets
    Ruwei GAO, Wei CHEN, Jiancheng ZHANG, Weicun FONG, Wei LI, Xiumei LI
    J. Mater. Sci. Technol., 2001, 17 (S1): 93-96. 
    Abstract   HTML   PDF (806KB)
    For both sintered and nanocomposite NdFeB magnets, deltaM(H) of the Henkel plot increases from zero, and reaches a peak, then decreases and changes to the negative values with increasing applied field. This shows that the intergrain interaction changes from the exchange-coup ling type into the magnetostatic interaction type. The magnetic field corresponding to the peak of deltaM(H) is slightly smaller than the coercivity of magnet. The peak of deltaM(H) for aligned sintered magnet is greater than that for misaligned magnet. deltaM(H) peak of the nanocomposite NdFeB magnets increases with decreasing grain sizes. It indicates that the effect of alignment field on the properties of magnet is similar to that of exchange-coupling interaction.
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    Research on the Ti-48Al-2Cr-2Nb automobile exhaust valve formed in permanent mold during centrifugal casting process
    Wenbin SHENG, Dong LI, Rui YANG, Yuyin LIU, Jingjie GUO, Jun JIA
    J. Mater. Sci. Technol., 2001, 17 (S1): 97-100. 
    Abstract   HTML   PDF (855KB)
    Ti-48Al-2Cr-2Nb automobile exhaust valves were formed with permanent mold centrifugal cast method and their surface layer structure, microstructure, elements distribution and mechanical properties were analyzed by SEM, XRD and EMPA etc. Furthermore, the HIPped valves were tested on 483Q diesel engine. Results showed that the element distribution of TiAl based alloy exhaust valves was uniform and their microstructure was refined. The typical mechanical properties of HiPped exhaust valves were sigma (b)=670 MPa, sigma (0.2)=527.5 MPa and delta =3%. Engine test showed that the valves had excellent airtightness and wear resistance properties and satisfied the requirements of engine successfully.
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    Microstructure evolution of Ti/BN powder blend during ball milling and heat treatment
    Jianlin LI, Leao HU, Yong ZHONG
    J. Mater. Sci. Technol., 2001, 17 (S1): 101-104. 
    Abstract   HTML   PDF (771KB)
    Ball milled Ti/BN composite powder was prepared by high energy ball milling for 40 h, using Ti and BN (the molar ratio of Ti/BN is 3:2) as starting materials. The as-milled composite powder consists of TiN, Ti and amorphous phase. TiN formed while the milled powder was annealed at 400℃. The heat treatment at 700℃ led to the formation of TiB2 and TiB. The nanocrystalline Ti and amorphous phase converted to TiN and TiB2 when the powder was heated to 1300℃.
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    Laser remelting of plasma sprayed thermal barrier coatings
    Gang ZHANG, Yong LIANG, Yingna WU, Zhongchao FENG, Bingchun ZHANG, Fangjun LIU
    J. Mater. Sci. Technol., 2001, 17 (S1): 105-110. 
    Abstract   HTML   PDF (1593KB)
    A CO2 continuous wave laser with defocused beam was used for remelting the surface of plasma sprayed ZrO2-8 Wt pct Y2O3 (8YSZ)/Ni22Cr10AlY thermal barrier coatings (TBCs) on GH536 superalloy substrate. Two main laser processing parameters, power and travel speed, were adopted to produce a completely remelted layer, and their effects on remelted appearance, remelting depth, density and diameter of depression, space of segment crack and remelted microstructure were evaluated. With energy of 4.0 to 8.0, an appropriate laser processing for applicable remelted layer was suggested.
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    Study on the precipitates formed by Double Glow Plasma Surface Alloying with tungsten-molybdenum
    Bin ZHAO, Jiansheng WU, Zhonghou LI, Xiaoping LIU, Zhong XU
    J. Mater. Sci. Technol., 2001, 17 (S1): 111-114. 
    Abstract   HTML   PDF (1043KB)
    Due to the slow cooling rate in the alloying furnace, large amount of brittle precipitates appear in the alloyed layers which are formed by the DGPSA (Double Glow Plasma Surface Alloying) with tungsten-molybdenum. It causes the mechanical properties of the samples to be seriously degraded. Qualitative phase analysis reveals that they are mainly composed of the p-phase, and a small amount of carbide, M6C. In this paper the microstructure and thermodynamic factors of the precipitates are exhaustively investigated. There are two transformation noses in the isothermal transformation (IT) diagram of the precipitates. As a major object of this work, an effective measure is offered to depress the deposition of the precipitates.
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    Laser surface strengthening process of Al-Si base alloy
    Haoran GENG, Yuchao NIU, Xianfa TIAN, Chuanzhong CHEN, Xiaoxia HOU
    J. Mater. Sci. Technol., 2001, 17 (S1): 115-118. 
    Abstract   HTML   PDF (1030KB)
    With a laser beam, the surface remelting/resolidifying treatment of ZL108 alloy was studied. Test results showed that a compact remelting layer was obtained with appropriate laser processing conditions and a suitable surface coating for laser energy absorption. The eutectic silicon phase in the laser-treating zone changed from the shape of thick-plate (stripe) into the very small grains, the structure was extremely fined, the hardness and wear resistance were improved greatly compared with that of the base alloy. A laser -treating layer, which is 3.5 mm thick and 5 mm wide, could be obtained.
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    Effects of Co species on the performance of pasted Ni electrode
    Xianxia YUAN, Yindong WANG, Feng ZHAN
    J. Mater. Sci. Technol., 2001, 17 (S1): 119-123. 
    Abstract   HTML   PDF (865KB)
    Effects of various Co species added by mechanically mixing with Ni(OH)(2) on the performance of Ni electrode were studied and the results were interpreted by means of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It was found that CoO, Co and CoO+Co all can improve the performance of Ni electrode to some extent and the effect of CoO was the most obvious. This could be attributed to several causes: all three forms of additives increased the reversibility of Ni(II)/Ni(III) redox reaction, enhanced the oxygen evolution polarization, improved the charging efficiency of Ni electrode, improved the lattice imperfection of Ni hydroxide and made it more beneficial to charge transfer and H+ diffusion processes.
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    Nanocomposite films of MoO3 xerogel with poly (ethylene oxide) (PEO) intercalation
    Yongshen HU, Wen CHEN, Qing XU, Runzhang YUAN
    J. Mater. Sci. Technol., 2001, 17 (S1): 124-126. 
    Abstract   HTML   PDF (531KB)
    (PEO)(x)MoO3.nH(2)O(x=0 similar to2) nanocomposite films were prepared by ion exchange method and polymer solution direct intercalation in sol-gel route. The synthesis and structure of the films were investigated by XRD, DSC, FTIR, etc. The results show that MoO3 xerogel has a layered structure, which arranges in b-direction. The interlayer distance Of MoO3 xerogel increases from 0.690 nm at x=0 to 1.308 nm at x=2 after heat treatment. PEO can be completely intercalated into the interlayer at x=0.5 similar to1 and has strong interaction with MoO3 host.
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    Fabrication of a W/W-Mo/Mo system layered flier-plate material
    Chuanbin WANG, Qing SHEN, Lianmeng ZHANG
    J. Mater. Sci. Technol., 2001, 17 (S1): 127-130. 
    Abstract   HTML   PDF (904KB)
    A kind of W/W-Mo/Mo system layered flier-plate material (LFP) was fabricated in this study by the methods of powder metallurgy and bonding together. Such LFP had high parallelism, planeness and densification and its density varied from 17.25x10(3) kg/m(3) to 10.22x10(3) kg/m(3) through a total thickness of 3.0 mm. The W-Mo interlayer of this LFP was obtained by hot-press sintering and its densification at 1573 K was studied. Then by using additives 4Ni-3Cu (in wt pct), the LFP was fabricated under 1573 K-30 MPa-60 min. The mechanism of the interfacial bonding of the W/W-Mo/Mo system LFP was also mainly investigated.
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    Electrochemical behavior of heteropoly acid anions adsorbed in electrodes modified with mesoporous molecular sieve silica
    Wenjiang LI, Zichen WANG, Changqing SUN, Muyu ZHAO, Youwei YAO, Aili CUI
    J. Mater. Sci. Technol., 2001, 17 (S1): 131-135. 
    Abstract   HTML   PDF (681KB)
    Heteropoly acid H4SiW12O48 (denoted as SiW12) was assembled with the mesoporous materials MCM-41 modified with 3-aminopropyltriethoxysilane (APTES) (denote MCM-41((m))). The electrochemical behavior of SiW12/MCM-41((m)) complexes-based electrode indicated SiW12 anion was adsorbed by MCM-41((m)). In MCM-41((m)) electrode, large voltammetric waves, showing that the electrostatic bound ions adsorbed in MCM-41((m)) were electrochemically active. The potential application as amperometric sensors for nitrite is anticipated.
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    Influence of hot deformation and cooling conditions on the microstructures of low carbon microalloyed steels
    Jinbo QU, Yiyin SHAN, Mingchun ZHAO, Ke YANG
    J. Mater. Sci. Technol., 2001, 17 (S1): 135-138. 
    Abstract   HTML   PDF (1732KB)
    The transformation behaviours and microstructural characteristics of three low carbon microalloyed steels were investigated. In particular, the effects of deformation and cooling conditions were studied by means of compression tests. It was found that at higher cooling rate (45℃/s), the transformation products was mainly granular bainite, the intragranular nucleated bainitic ferrite grew in different directions, and the second phase particles of M/A constituent uniformly distributed in the bainitic ferrite matrix. When the cooling rate was decreased to 25℃/s or 15℃/s, the resulting microstructure was converted to a mixture of polygonal hypoeutectoid ferrite and granular bainite, whose percentage was reduced. As the cooling rate was lowered to 8℃/s, the microstructure consisted chiefly of polygonal ferrite with a few amounts of M/A and pearlite.
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    Two-photon absorption and nonlinear optical properties of a new organic dye DEASPI
    Guangyong ZHOU, Xiaomei WANG, Dong WANG, Chun WANG, Xian ZHAO, Zongshu SHAO, Minhua JIANG
    J. Mater. Sci. Technol., 2001, 17 (S1): 139-142. 
    Abstract   HTML   PDF (727KB)
    A new organic dye trans-4- [p-(N,N-diethylamino) styryl]-N-methylpyridinium iodide (abbreviated' as DEASPI thereafter) with large two-photon absorption (TPA) cross section and excellent upconverted lasing properties was synthesized. The melting point and decompound point were measured to be 230 degreesC and 264.7 degreesC respectively. The molecular TPA cross section was measured to be sigma (2)=6.9x10(-48) cm(4).s/photon at 1064 nm by using an open aperture Z-scan system. The linear and nonlinear optical properties of this dye were systematically studied. The highest net upconversion efficiency from the absorbed pump energy to the output upconverted lasing energy is as high as 18.6% at the pump energy of 2.17 mJ from a mode-locked Nd:YAG ps laser. The nonlinear transmittance at the wavelengths from 720 to 1100 nm was measured. The dye solution also shows a clear optical power limiting effect.
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    Study on heat hardening mechanism of starch composite binder for sand mold (core) by IR spectra
    Xia ZHOU, Jinzong YANG, Qin GAO, Guohui QU
    J. Mater. Sci. Technol., 2001, 17 (S1): 143-146. 
    Abstract   HTML   PDF (613KB)
    The heat hardening mechanism of starch composite binder for sand mold (core) was studied by way of IR spectra. It is thought that the bonding strength of molding sand is mainly depended on the strength of the adhesive membrane itself. During heating the binder at certain temperature between 160 similar to 200 degreesC for one hour, a special composite structure is formed because of the interactions between different components, thus, it has higher low-temperature drying strength, better humidity resistance and higher high-temperature strength.
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    A new kind of Al2O3 supporter for inorganic membranes
    Fude LIU, Senfeng CHEN, Emma CHEN
    J. Mater. Sci. Technol., 2001, 17 (S1): 147-150. 
    Abstract   HTML   PDF (1160KB)
    In this experiment, in order to prepare high quality inorganic membranes which are conventionally not tough enough to bear high pressure, we tried three kinds of CaO-MgO-SiO2 adhesives. Unlike conventional adhesives used for porous supporters, these three kinds of adhesives have high mechanical strength, which ensure the high properties of the membranes with high porosity. Adhesive, sintering temperature, poremaker (or pore forming material) and holding heat time, were taken into account. The relationship between the properties of membranes and the four factors were found out through a kind of orthogonal experiment named Lg(3(4)). Then we got a better way to the preparation of Al2O3 membranes which could have porosity over 45% and even remain strength over 40 MPa.
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    Distribution of longitudinal inherent strains in multiple-passes welding
    Peng HE, Jiuhai ZHANG, Toshio Terasake, Testuya Aliyama
    J. Mater. Sci. Technol., 2001, 17 (S1): 151-154. 
    Abstract   HTML   PDF (544KB)
    A fundamental theory for the analysis of residual welding stresses and deformation based on the inherent strain distribution along the welded joint is introduced. The computing method of distribution of longitudinal inherent strains in multiple-passes welding in heavy plate weldment is proposed. Distribution of longitudinal inherent strains in one-pass welding and two-passes welding are compared and analyzed. The effect of cutting on inherent strain is discussed.
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    Preparation QT3.5-3.5 graphite lubricant material with semi-solid casting technology
    Peng ZHANG, Yunhui DU, Daben ZENG, Jianzhong CUI, Limin BA
    J. Mater. Sci. Technol., 2001, 17 (S1): 155-158. 
    Abstract   HTML   PDF (799KB)
    For the first time, the distribution of graphite particles in QTi3.5-3.5 graphite ingot was studied by using semi-solid casting technology. The results show that: the relationship between solid fraction and stirring temperature of QTi3.5-3.5 graphite slurry is y=759.4-0.711x (where y is solid fraction, x is stirring temperature). With the increasing of solid fraction of QTi3.5-3.5 graphite slurry, the agglomeration of graphite particles in ingot reduces gradually. The condition to prepare QTi3.5-3.5 graphite lubricant material with even distribution of graphite particles is that the solid fraction of QTi3.5-3.5 graphite slurry is larger than 40%.
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    Preparation and microstructure of as-cast in-situ Ti-6Al/TiB composites
    Erlin ZHANG, Yunxue JIN, Songyan ZENG, Zhaojun ZHU
    J. Mater. Sci. Technol., 2001, 17 (S1): 159-162. 
    Abstract   HTML   PDF (885KB)
    TiB reinforced titanium composites have been successfully synthesized by adding the Al/TiB2 master alloy into titanium alloy. The phase constituent and the microstructure have been studied by XRD and SEM. Compared with the standard values, the lattice parameter of TiB calculated from the XRD pattern indicates that the synthesized TiB is of prefect crystal structure. The microstructure has shown that high aspect ratio fibrous TiB has been found, which homogeneously distribute in the matrix in a random way. The size is about 100 μm in length, less than 2.5 μm in diameter and the aspect ratio is greater than 40. Deep etched microstructures show that some coarse hollow TiB corresponding to primary TiB are also formed with smooth and flat surface and random transverse section. The size is about 100 μm in length and greater than 10 mum in diameter. The solidification process has also been analyzed.
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    Surface and interface analyses of UHV evaporated Nb/AlOx/Nb tri-layers
    Shahzad Naseem, Nudrat Humera
    J. Mater. Sci. Technol., 2001, 17 (S1): 163-166. 
    Abstract   HTML   PDF (892KB)
    We have prepared Nb thin films with e-beam evaporation under UHV conditions. Al thin films were deposited by resistive heating in the UHV chamber. The preparation of these films and the tri-layers of Nb/AlOx/Nb were intended for their use in Josephson junctions. The surface studies of these films were undertaken by using scanning electron microscope and atomic force microscope in the non-contact mode, whilst the interface analysis was carried out by depth profiling using scanning Auger microprobe. These studies have revealed that Nb films grown on AlOx are smoother than the ones grown on Si. Further, it is seen that Al diffuses into Nb on both sides and that the interface is very broad. This intermixing of various materials results in the failure of the tri-layers when subjected to application in SQUIDs.
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    Polarization properties of ferroelectric superlattice studied by Monte Carlo simulation
    Guiwu LU, Hairui XIA, Pijun LIU
    J. Mater. Sci. Technol., 2001, 17 (S1): 167-170. 
    Abstract   HTML   PDF (673KB)
    The polarization property of a ferroelectric superlattice formed from two alternating materials was studied using Monte Carlo computer simulation. Our study has been developed in a framework of the transverse king model with nearest-neighbor interactions. Both the effect of the transverse field and interface coupling strength have been taken into consideration. In view of our results which is in good agreement with previous theoretical results, it is concluded that the Curie temperature of the superlattice increases with the increase of the interface coupling strength J(AB) The remanent polarization and saturation coercive force of the superlattice are also presented.
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    Preparation of TiB2 coated cathode of Al electrolysis
    Bing LI, Fei ZHOU, Zhuxian QIU
    J. Mater. Sci. Technol., 2001, 17 (S1): 171-173. 
    Abstract   HTML   PDF (530KB)
    TiB2 coating was prepared by electrodeposition from KCl-KF-K2TiF6-KBF4 molten salts on graphite substrate at 810 degreesC. The coating is affected by protective gas, current density, and electrolyte compositions. From a series of tests it can be concluded that when the following conditions are used, TiB2 coating will be compact and homogeneous, and the layer of coating has higher TiB2 content, and also has good coherence to graphite matrix. The electrolysis conditions are as follows: KCl 5%, KF 60 similar to 70%, K2TiF6 10%, KBF4 20 similar to 30%, (mole fraction), current density being 0.4 similar to0.8 A/cm(2) and Ar being used as protective gas.
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    Separated eutectic structure of Al-11 wt pct Si alloy under direct magnetic field
    Yan WANG, Jiang JIANG, Zhonghua ZHANG, Xiufang BIAN
    J. Mater. Sci. Technol., 2001, 17 (S1): 174-182. 
    Abstract   HTML   PDF (687KB)
    An investigation has been made on the effect of a direct magnetic field on the structure of eutectic Al-11 wt pct Si alloy. At the superheated temperature of 750 degreesC, a separated eutectic structure in the alloy occurs under the condition of the magnetic induction intensity up to 0.24 T. A great number of primary Si particles in the Al-11 wt pct Si alloy are segregated to the surface layer of the specimens. The microstructure of the alloy consists of primary Si particles in the surface layer and Al Matrix in the inner part of the specimen. Moreover, the higher the superheated temperature, the more remarkable the segregation trend. The mechanism of the formation of separated eutectic has been discussed.
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    Regularities of formation of ternary intermetallic compound between transition elements
    Lixiu YAO, Jie YANG, Chenzhou YE, Nianyi CHEN
    J. Mater. Sci. Technol., 2001, 17 (S1): 183-185. 
    Abstract   HTML   PDF (496KB)
    Four parameters, phi (electronegativity), n(ws)(1/3) (valence electron density in Wagner-Seitz cell), R (Pauling's metallic radius) and Z (number of valence electrons in atom), and the pattern recognition methods were used to investigate the regularities of formation of ternary intermetallic compounds between three transition elements. The obtained mathematical model expressed by some inequalities can be used as a criterion of ternary compound formation in "unknown" phase diagrams of alloy systems.
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    Microstructure of the Al2O3/Al2O3 joint brazed with Cu-Zn-Ti filler metal
    Hongyuan FANG, Jianguo YANG, xiuyu YU
    J. Mater. Sci. Technol., 2001, 17 (S1): 186-187. 
    Abstract   HTML   PDF (804KB)
    Microstructure and interface reactions of Al2O3 joints brazed by Cu-Zn-Ti alloy were studied by using SEM, EDS and XRD. The effects of brazing temperature and Ti content on interfacial reactions and microstructure were investigated, and the action of adding Zn into brazing alloy was also studied. TiO, Ti3Al and CuTi were formed at the interface of ceramics and the filler metal, while CuTi, Cu3Ti and alpha -Cu were found in the brazing. The thickness of the reaction layer increased with increasing of brazing temperature, under the same brazing process, the thickness increased with the Ti content.
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    Reaction path research of TiC/Si diffusion couple experiment
    Guoyou GAN, Xiuhua CHEN, Jingchao CHEN, Xiaolong ZHOU
    J. Mater. Sci. Technol., 2001, 17 (S1): 189-190. 
    Abstract   HTML   PDF (375KB)
    Interaction between single crystal Si and TiC block was studied by electron probe micro analysis (EPMA). The distribution of the reaction products from Si to TiC is reported. The diffusion kinetics constant of Si is given. The implications of the observed microstructure are discussed.
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ISSN: 1005-0302
CN: 21-1315/TG
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