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Search Results: 1 - 10 of 13547 matches for " Shanghai Jiao Tong University "
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EFFECT OF REINFORCEMENT VOLUME FRACTION ON PRECIPITATION IN MATRIX OF SiC_p/AI COMPOSITE
LIN Junshan,LI Pengxing,WU Renjie Shanghai Jiao Tong University,Shanghai,China postdoctoral,
LIN Junshan
,LI Pengxing,WU Renjie Shanghai Jiao Tong University,Shanghai,China postdoctoral,Institute of Composite Materials,Shanghai Jiaotong University,Shanghai,China

金属学报(英文版) , 1993,
Abstract: The differential scanning calorimetric(DSC) and transmission electron microanalysis (TEM) techniques were used to study the kinetic process of precipitation in matrix of cast SiC_p/2024 composites.The results showed that precipitation reactions of GP zone and intermediate phase S'(Al_2CuMg)in the composites were accelerated compared with SiC-free material,the peak temperatures of both reactions were decreased.The reaction enthalpies of both the GP zone and intermediate phase S' formation in the matrix were substantially decreased after the addition of SiC.TEM analysis found that the alloying element Mg segregated at the SiC/Al interfaces,and was depleted in the matrix near the interface.The precipitation-free zones(PFZ) and precipitation-sparse zones(PSZ) formed near the interfaces,as a results,the volume fraction of precipitates in matrix was reduced.
STRENTHENING MECHANISM OF MODULATED STRUCTURE INITIATED BY SPINODAL DECOMPOSITION
Spinodal分解始发形成调幅组织的强化机制

XU Zuyao School of Materials Science,Engineering,Shanghai Jiao Tong University,Shanghai,
徐祖耀

金属学报 , 2011,
Abstract: Through reviewing of a limited number of literatures regarding strengthening mechanism of modulated structure initiated by spinodal decomposition, it is found that the yield strength of aged alloy is mainly dependent on stress field built by the composition different between two precipitate phases which can be characterized by difference between lattice parameter Δa and is independent on modulate wave length and volume fraction of precipitate phase. However, in the ageing courses, the changes in yield stress and Δa did not show a linear relationship. The present author considers that this may be attributed to the local destruction of periodicity of modulated structure, causing change in stress field during ageing and suggests a yield stress equation: σc=MBΔa/a, in which M denotes a sum factor including Taylor (or Schmidt) factor and elastic constants, B, a factor represent the response of local stress field changed the function of Δa/a, Δa, the difference between lattice parameters of two precipitate phases and a, the average lattice parameter. This equation and the B value need to be confirmed and estimated.
NUMERICAL SIMULATION OF MECHANICAL BEHAVIOR DURING LOCAL POSTWELD HEAT TREATMENT
JH,Wang,H Lu,H Murakawa Shanghai Jiao Tong University,Shanghai China Osaka University,Japan,
JH
,Wang,H. Lu and H. Murakawa Shanghai Jiao Tong University,Shanghai .China Osaka University,Japan

金属学报(英文版) , 2000,
Abstract: Local postweld heat treatment (PWHT)is usually performed when it is impractical to heat treat the whole vessel in a furnace, Many factors have an influence on PWHT procedures, such as size of the pipe,heated widths, insulation conditions, heating rates soak temperatures and hold times, material composition etc,. However up to now the influences these factors have on PWHT are not very clearly understood and different criteria for sizing the parameters can be found in different codes. This study provides a direct method to assess the effectiveness of local PWHT.An axisymmetrical model was used based on the thermal-visco-elastic-plastic Finite Element Method with the consideration of creep phenomena. By using this method both temperature and stress distributions can be simulated during whole local PWHT history. The computation results of temperature distributions and the strain histaries during local PWHT are compared with the experiments, and good agreements are obtained, Investigations show that the thermal stresses induced by local PWHT are much affected by creep behavior and the changes of Young's Modulus. The study of stress relief history shows that the stresses decrease quickly in the heating stage, then decrease slowly according to creep law in the hold stage and then studdenly increase when the cooling stage starts. The study shows the possibility that through a series of computations the effects of many factors can be assessed and the optimum parnmeters can be found. Compared with the heated widths based apon some applicable codes, it is found that a heated area of 2.5 on either side of the weld seems more reasonable.
MICROSTRUCTURE AND DUCTILITY OF RE DOPED RAPIDLY SOLIDIFIED NiAl
SUN Baode,LIN Dongliang,YANG Gencang,ZHOU Yaohe Shanghai Jiao Tong University,Shanghai,ChinaNorthwesten Polytechnic University,Xi'an,China
金属学报(英文版) , 1995,
Abstract: The paper investigated the effects of RE on the microstructure and ductility of melt-spun Al-63.3at.%Ni and Al-66.4at%Ni.For Al-63.3at.%Ni without RE the microstructure is a mixture of equiaxed martensitic grains and B2 NiAl grains,but after addition of 0.2wt% RE a complete supersaturated B2 NiAl results,and its elongation is enhanced from 0.9%(without RE) to 1.4%(with 0.2wt%RE).For Al-66.4at.%Ni without RE the microstructure is coarse equiaxed martensitic grains with Ni3Al precipitated at the GBs.But complete martensitic grains and supersaturated single phase,B2 NiAl,would result with addition of 0.05wt%RE and 0.2-0.8wt%RE respectively.The elongation of Al-66.4at.%Ni without RE is only 0.8%.With the addition of 0.05, 0.2 and 0.8wt%RE.the elongation can reach 2.6,3.0 and 3.2% respectively.The addition of RE can change the fracture mode from intergranular fracture(without RE) to a mixture of intergranular and transgranular fracture or entirely transgranular fracture.The mechanisms of microstructure formation and ductility enhancement are analyzed.
Application of stress functions and its dual theory to finite element
应力函数及其对偶理论在有限元中的应用

Huang Ruoyu Wu Changchun School of Civil Engineering & Mechanics,Shanghai Jiao Tong University,Shanghai,China,
黄若煜
,吴长春

力学学报 , 2004,
Abstract: Cosserat's continuum is a generalized model of the classical elasticity. Many important elastic problems can be taken as its special case subjected to some geometric/mechanical constrains. In some of these problems, there exist the C~1 continuity difficulty in finite element formulation when the elements are constructed in the displacement space. Using Cosserat's continuum, the present work discusses the reason of the appearance of the C~1 continuity difficulty. It is noted that when geometric or/and mechanical constraint(s) is(are) enforced upon Cosserat's model there must exist C~1 continuity requirement for either displacement field or stress function field. And the key point is that only one of these two fields has the C~1 continuity requirement and the other is free from this difficulty. So for some problems with C~1 continuity difficulty in displacement formulation, it is a natural approach to avoid this difficulty by using formulation in stress function space. Nevertheless, the finite element constructed in stress function space is not convenient to apply because stress functions have no explicit physical meaning and then it is difficult to appoint boundary condition for them. For this practical reason, the dual theory of stress functions is presented to provide an approach to transform an clement with stress functions as degree of freedom (DOF) to the element with ordinary displacement as DOF. Based on this dual theory, a general way to construct finite element using stress functions is discussed.
A Method of Etching Submicron Vertical Silicon Screen
一种亚微米垂直硅墙的刻蚀方法

Tang Yusheng/LSI Microfabrtcating Institute,Shanghai Jiao Tong UniversityJiang Jianfei/LSI Microfabrtcating Institute,Shanghai Jiao Tong University,
汤玉生
,蒋建飞

半导体学报 , 1989,
Abstract: 亚微米垂直硅墙的制备是垂直硅薄膜耦合约瑟夫逊结的关键工艺.本文作者在普通光刻设备基础上,开发了一种在〈100〉硅片上制备亚微米硅墙的刻蚀方法:首先用普通光刻手段刻出较宽的墙区;其次,对非墙区进行迭加注入掺杂;第三,杂质高温横向扩散,第四,掺杂选择性刻蚀;第五,高温氧化减薄.实验结果表明,这种方法可以获得墙宽为0.29μm,墙高为1μm左右的硅墙,而且还有一定的改进潜力.
Method for Fabricating Submicron Spaces
一种制作亚微米间隔的方法

Xie Kexun/Microelectronics Technical Institute,Shanghai Jiao Tong UniversityJiang Jianfei/Microelectronics Technical Institute,Shanghai Jiao Tong UniversityXie Ying/Microelectronics Technical Institute,Shanghai Jiao Tong University,
谢可勋
,蒋建飞,谢缨

半导体学报 , 1989,
Abstract: 本文研究了利用光刻图形转移过程中,湿法化学刻蚀存在的侧向钻蚀,通过对钻蚀程度的控制获得小于0.5μm的线条间隔.
INFLUENCE OF AUSTENITE STRENGTHENING ON MARTENSITIC TRANSFORMATION IN Fe-Mn-C ALLOYS
Fe—Mn—C合金奥氏体强化对马氏体相变的影响

PAN Mu,XU Zuyao T Y Hsu Shanghai Jiao Tong University XU Zuyao,professor,Dept of Materials Science,Shanghai Jiao Tong University,Huashan Road,Shanghai China,
潘牧
,徐祖耀

金属学报 , 1989,
Abstract: The M_5 temperature and the yield strength of austenite at M_5 tem-perature have been measured for five Fe-Mn-C alloys. The experimental results showthat there is a linear relationship between them. The effect of the solution strength-ening of austenite on martensite morphology is also studied. It is pointed outthat there is a characteristic temperature of strengthening in austenite, T_c. Marten-site morphology is mainly dislocated laths when M_5>T_c, and is mainly twinnedplates when M_5
Effects of Nitrogen Concentration on Microstructure and Antibacterial Property of Copper-Bearing Austenite Stainless Steels

Zhixia ZHANG Laizhu JIANG Gang LIN Zhou XU School of Material Science,Engineering,Shanghai Jiao Tong University,Shanghai,China Technology Center,Baoshan Iron & Steel CoLtd,Shanghai,China,

材料科学技术学报 , 2008,
Abstract: Austenite antibacterial stainless steels have been found to have wide applications in hospitals and food indus-tries. In recent years epsilon copper precipitation in antibacterial stainless steels has obtained much research interest due to its antibacterial action. The objective of this study was to determine the effects of nitro-gen concentration on the precipitation of epsilon copper and antibacterial property. Two kinds of austenite antibacterial stainless steels containing copper and different nitrogen concentration (0.02 and 0.08 wt pct, re-spectively) were prepared and the microstructures were characterized by a combination of electron microscopy and thermodynamic analysis. A mathematical expression was deduced to predict the effect of nitrogen con-centration on the activity coefficient of copper, In(fCu/focu)=0.53524 4.11xN-0.48x2N. Higher nitrogen was found to increase the free energy difference of copper concentration distribution between precipitation phase and austenite matrix, stimulate the aggregation of copper atoms from austenite, increase the precipitation amount and consequently enhance the antibacterial property of steel.
Annealing High Resistivity CdZnTe Wafers under Controlled Cd/Zn Partial Pressures
Wanwan LI,Wenbin SANG,Bin ZHANG,Jiahua MIN,Fang YU,
Wanwan LI
,Wenbin SANG,Bin ZHANG,Jiahua MIN and Fang YU School of Material Science and Engineering,Jiading Campus,Shanghai University,Shanghai,China Institute of Composites Materials,Shanghai Jiao Tong University,Shanghai,China

材料科学技术学报 , 2004,
Abstract: In order to improve the performances of CdZnTe γ-ray detector, it is key issue to get the crystal with high quality. Equilibrium partial pressures, PCd and PZn, over Cd1-xZnx melt were estimated based on thermodynamic relationship and then Cd0.9Zn0.1Te wafers were annealed under controlled Cd/Zn partial pressures provided by Cd1-xZnx alloy reservoir. The experimental results show that when CdZnTe wafers are annealed under the equilibrium partial pressures provided by Cd0.99Zn0.01 alloy reservoir for 5 days or more at 1073 K, the resistivity of the wafer can be raised by 6 times and IR transmittance raised by 10% or more, the size and density of Te precipitates are greatly reduced.Moreover, losing of Zn from the surface can be avoided, which leads to improvement of the Zn radial distribution.In addition, the relationship between the electrical performances of the wafers and different controlled pressures is also discussed.
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