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Effect of Heat Input on the Microstructure and Mechanical Properties of 07MnCrMoVR Weld Joints

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Chinese Journal of Mechanical Engineering 2011年第2期24卷 207-213页

作者： xu Lianghong zhang jun CHEN Yanqing Shougang Research Institute of Technology Beijing 100043 China

As a new type of low cracking suscepbility high strength steel,07MnCrMoVR steel has excellent weldability,with low carbon equivalent and cold cracking susceptibility ***,there are still some problems when this steel is on the outdoor actual welding condition,such as having some extend cold cracking suscepbility and embrittlement of heat affected ***, researching works for the welding of this steel mostly focus on the evaluation the weldability of it,only few works are concentrated in how the heat input affecting the embrittlement of *** goal of this research is to study the effect of heat input on the embrittlement of the heat affected zone so as to get the optimal welding heat input range for *** this paper,38 mm 07MnCrMoVR steel made by Shougang is welded by manual arc welding technology,and the effect of heat input on the microstructure and mechanical properties of weld joints is also investigated by use of optical microscope（OM）,scanning electron microscope（SEM）,mechanical properties testing machines and Viker hardness *** microstructure and fractography observation results and the mechanical properties testing results indicate that the 07MnCrMoVR steel made by Shougang has a wide adaptable range for heat input,and when the heat input is in the range of 15-42 kJ/cm,the toughness of the weld joints is *** the increase of heat input,the impact toughness of weld zone and heat affected zone decrease,whereas the tensile strength of the weld joints does not change at *** microstructure of the weld is acicular ferrite with small amount of proeutectoid ferrite,and with the increase of heat input,the ratio of proeutectoid ferrite and the amount of M-A constituent increase,as well as the grain size and the width of the bainite lath in coarsened grain heat affected zone. Fractography results show that with the increase of heat input,the number of dimples in impact fracture specimens decreases,and the cleavage patterns incre

关键词： 07MnCrMoVR heat input microstructure impact toughness heat affected zone

Slave-Fermion Mean-Field Theory of Heisenberg Model

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Communications in Theoretical Physics 2007年第2X期48卷 363-365页

作者： xu Lei zhang jun School of Physics Xinjiang University Urumqi 830046 China

A nearly half-filled two-dimensional Heisenberg model is investigated. A slave-fermion method with fermions as the charge carriers and bosons as the spin carriers is proposed. The ground state shows antiferromagnetic ... 详细信息

关键词： slave-fermion correlation function static susceptibility

Fridman’s Invariant, Squeezing Functions, and Exhausting Domains

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Acta Mathematica Sinica,English Series 2019年第10期35卷 1723-1728页

作者： Fu Sheng DENG xu jun zhang School of Mathematical Sciences University of Chinese Academy of Sciences

We show that if a bounded domain Ω is exhausted by a bounded strictly pseudoconvex domain D with C^2 boundary, then Ω is holomorphically equivalent to D or the unit ball, and show that a bounded domain has to be hol... 详细信息

关键词： Squeezing function Fridman's invariant exhausting domain

Semisolid microstructure evolution of AZ91D alloy under high shear rate

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Rare Metals 2011年第1期30卷 99-103页

作者： ZHU Guanglei xu jun zhang Zhifeng LIU Guojun National Engineering ＆ Technology Research Center for Nonferrous Metal Matrix Composites General Research Institute for Nonferrous MetalsBeijing 100088China

Experimental work was undertaken to investigate the effect of rotation speed on the solidification microstructure of AZ91D alloy using a twin-screw slurry *** numerical simulation was used to investigate the effect of rotation speed on the flow filed and temperature field of the *** was found that increasing the rotation speed could give rise to substantial grain refinement,which can be attributed to the increase of effective nucleation rate caused by the extremely uniform temperature and dispersing any potential clusters of nucleation agents in the bulk liquid under dispersive mixing.

关键词： magnesium alloys microstructural evolution shearing grain refinement solidification

Interference Pattern of Density-Density Correlation for Incoherent Atoms with Vortices Released from an Optical Lattice

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Chinese Physics Letters 2011年第1期28卷 26-29页

作者： xu Zhi-jun zhang Dong-Mei LIU Xia-Yin College of Science Zhejiang University of Technology Hangzhou 310023

For a series of incoherent condensate atomic clouds with vortices （an orbital angular momentum） released from an optical lattice, the density-density correlation function of this freely expanding ultracold gases is theoretically investigated. It is shown that the nonzero angular momentum of the atoms has an important effect on the fringe pattern of density-density correlation. Particularly, for a short expansion time, even the rotation direction of the atoms could have an observable effect on the fringe pattern. Observation of this specific fringe pattern would constitute experimental evidence for the presence of a vortex in an atomic condensate.

关键词： Quantum gases, liquids and solids Optics, quantum optics and lasers Statistical physics and nonlinear systems

Annular electromagnetic stirring——a new method for the production of semi-solid A357 aluminum alloy slurry

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Acta Metallurgica Sinica(English Letters) 2009年第6期22卷 408-414页

作者： Guanglei ZHU jun xu Zhifeng zhang Yuelong BAI Likai SHI National Engineering ＆ Technology Research Center for Non-ferrous Metal Matrix Composites General Research Institute for Non-ferrous Metals Beijing 100088 China

A new method for producing semisolid slurry, annular electromagnetic stirring （AEMS）, to refine and spheroidize grains was exploited. Experimental work was undertaken to investigate the effects of cooling rate, stirring power and stirring time on the solidification behavior of A357 alloy using A-EMS. It was found that increasing the cooling rate and stirring power gave rise to substantial grain refinement, which could be attributed to the increase of effective nucleation rate caused by the extremely uniform temperature and composition fields in the bulk liquid during the initial stage of solidification. Results showed that a fully grain refined spherical structure could be obtained using proper processing conditions within 10 s.

关键词： Semisolid Annular electromagnetic stirring A357

Preparing Process of Cerium Acetate and Rare Earth Acetate

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Journal of Rare Earths 2004年第Z1期22卷 26-31页

作者： Qiao jun Ma Ying xu Yanhui zhang jun Chang Shu Hao Xianku Baotou Research Institute of Rare Earth Baotou 014010 China Baotou Research Institute of Rare Earth Baotou 014010 China Baotou Research Institute of Rare Earth Baotou 014010 China Baotou Research Institute of Rare Earth Baotou 014010 China Baotou Research Institute of Rare Earth Baotou 014010 China Baotou Research Institute of Rare Earth Baotou 014010 China

Preparing process was presented and the influences of concentration of acetic acid, reaction temperature, the ratio of cerium carbonate and acetic acid, heat preservation time to the yield of cerium acetate were *** crystalline cerium acetate and rare earth acetate such as ( La, Ce, Pr, Nd) (Ac) 3, ( Ce, Pr, Nd) (Ac) 3, ( Pr, Nd, Er,Y) (Ac) 3 and yttrium acetate were prepared under this *** shape, structure and composition of the crystals were determined by the methods of SEM, TG-DTA, X-ray diffraction and chemical *** optimum prepared conditions of cerium acetate were *** prepared process has characteristics such as simple process route, low cost, high yield, good quality, no pollution to environment, etc.

关键词： cerium acetate, rare earth acetate, composition rare earths

Effect of closed-couple gas atomization pressure on the performances of Al-20Sn-1Cu powders

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Rare Metals 2008年第4期27卷 439-443页

作者： ZHAO Xinming xu jun ZHU xuexin zhang Shaoming National Engineering and Technological Research Center for Non-ferrous Metals Composites General Research Institute for Nonzferrous Metals Beijing 100088 China

Al-20Sn-1Cu powders were prepared by gas atomization in an argon atmosphere with atomizing pressures of 1.1 and 1.6 MPa. The characteristics of the powders are determined by means of dry sieving, scanning electron microscopy （SEM）, optical microscopy （OM）, and X-ray diffractometry （XRD）. The results show that the powders exhibit a bimodal size distribution and a higher gas pressure results in a broad size distribution. All particles in both cases are spherical or nearly spherical and satellites form on the surface of coarse particles. Dendritic and cellular structures coexist in the particle. With decreasing particle diameter, the secondary dendrite arm spacing （SDAS） decreases and the cooling rate increases. The particles processed under high gas atomization pressure （1.6 MPa） exhibit a lower SDAS value and a higher cooling rate than those of the same size under low gas atomization pressure （1.1 MPa）. The XRD results show that the Sn content increases with decreasing particle size.

关键词： powder production Al-Sn-Cu alloy gas atomization rapid solidification particle size distribution

Triterpene Acids from Cynoglossum amabile

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Chemical Research in Chinese Universities 2009年第3期25卷 404-406页

作者： xu Qing-jun zhang De-zhi DANG Li-juan LI Kun-ping College of Pharmacy Guangdong Pharmaceutical University Guangzhou 510006 P. R. China

Cynoglossum amabile Stapf et Drumm is widely distributed in southern China, which has been used as an anti-inflammatory, antihepatitis, anticystitis agent in Chinese folk medicine. However, only a few phytochemical researches have been performed . Therefore, a systematic chemical investigation of it was carried out. In this work, we further investigated the chemical constituents and ten compounds were obtained, three of which were triterpene acids.

关键词： Cynoglossum amabile Triterpene acid Amabilic acid