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Comparison of Ferrite Refinement Mechanisms by Different Processing Schedules in 08 and 2.Mn Steels

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Journal of university of science and Technology Beijing 2001年第3期8卷 218-223页

作者： Ping Yang Feng’e Gui, Shicai Ma material science and {2. school, university of science and Technology Beijing, Beijing 100083, china Univ Sci & Technol Beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China

The influence of deforming temperature on ferrite refinement was analyzed by comparing the microstructures obtained by deformation at above A(r3), in two-phase region of (alpha + gamma) and at below A(t) in clean 08 and 2.Mn steels. The results indicate that ferrite refinement through strain induced transformation by deformation at above A(r3) is more effective than that by deformation simply through ferrite dynamic recrystallization. The main problem of ferrite refinement by deformation at below A(r3) is the inhomogeneity of microstructure which is controlled by the orientations and sizes of ferrite grains and the distribution of second phases. Ferrite dynamic recrystallization after strain induced transformation can further effectively refine ferrite.

关键词： clean carbon steel strain induced transformation grain refinement ferrite dynamic recrystallization

Microstructure Characteristics and Apparent Viscosity of Hypereutectic Al-2.%Si Alloy Melt During Semi-solid State Stirring

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Journal of university of science and Technology Beijing 2001年第2期8卷 126-128页

作者： Yanjun Li, Weimin Mao, Zisheng Zhen, Xueyou Zhong (material science and {2. school, university of science and Technology Beijing, Beijing 100083, china) Univ Sci & Technol Beijing Mat Sci & Engn Sch Beijing 100083 Peoples R China

The microstructural evolution and apparent viscosity of hypereutectic Al-2.%Si alloy during semi-solid state shearing were studied with a Searte type viscometer. When the alloy melt was continuously stirred from 72. degreesC to eutectic temperature, the primary Si crystals were gradually changed from elongated platelets to near-spherical shapes. It was found that some nondendritic a-phase formed when the melt was stirred below 585 degreesC. The experiment showed that the semi-solid stirring had strong effect on inhibiting the anisotropic growth of Si crystals during solidification. The apparent viscosity of the alloy melt increased slowly with the decreasing of temperature before the formation of nondendritic alpha -phase, which caused the dramatic increase of apparent viscosity.

关键词： hypereutectic Al-Si alloy solidification structures apparent viscosity

Irradiation Damage of Oxide Dispersion Strengthened Ferritic Steel after Recrystallization

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International Journal of Minerals,Metallurgy and materials 1998年第3期12卷 160-164页

作者： Benfu Hu Shunmi Peng H Takahashi(material science and {2. school, university of science and Technology Beijing, Beijing 100083, china)(Faculty of {2., Hokkado university, Sapporo 060, Japan) material science and {2. school University of Science and Technology Beijing Beijing 100083 China Faculty of engineering Hokkado University Sapporo 060 Japan

The evolution of secondary defects and the characteristics of the void swelling of electrons irradiated Oxide Dispersion Strengthened Ferritic Steels (ODS steels) after recrystallization were studied. It was found that recrystallization increases the void swelling of ODS steel as compared with solution and injected He+ + D+ *** are two size ranges of voids formed in recrystallized ODS steel during irradiation, and bubbles can be preferential sites for the void formation. Polycrystal with low density of defects is formed, and sites where point defects disappear by irradiation decrease. This is the main reason for the increase of void swelling of ODS steel after recrystallization.

关键词： ODS steel recrystallization, electron irradiation

The characteristics of arc beam shaping in hybrid plasma and laser deposition manufacturing

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science china(Technological sciences) 2006年第2期49卷 238-247页

作者： ZHANG Hai’ou1, QIAN Yingping1,3, WANG Guilan1 & ZHENG Qiguang2.1. school of material {2. and Technology, Huazhong university of {2. and Technology, Wuhan 430074, china 2. Institute of Laser Technology and engineering, Huazhong university of {2. and Technology, Wuhan 430074, china 3. Mechanical engineering College, Hubei university of Technology, Wuhan 430068, china 1. school of material {2. and Technology Huazhong University of Science and Technology Wuhan 430074 China 3. Mechanical engineering College Hubei University of Technology Wuhan 430068 China 2. Institute of Laser Technology and engineering Huazhong University of Science and Technology Wuhan 430074 China

As a new direct metal prototyping technology,the hybrid plasma and laser deposition manufacturing (PLDM) is proposed in this paper. In order to figure out the characteristics of plasma arc beam and mould in the PLDM process of high temperature alloy, the high speed CCD camera is used to obtain the picture around the plasma arc. Afterwards the sketch of picture is clearly obtained. And the effect of laser parameter, such as average power, pulse width, pulse repetition frequency and the angle between laser beam and plasma arc beam on the plasma arc appearance, is studied experimentally. The results show that the modality of plasma arc beam is markedly influenced by laser beam. And the improvements of shape precision and surface state of the layer deposited by PLDM are confirmed.

关键词： plasma hybrid laser, direct deposition, plasma arc beam, molding character, high-temperature alloy.

A NOVEL INTERPRETATION OF CONCENTRATION DEPENDENCE OF VISCOSITY OF DILUTE POLYMER SOLUTION

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Chinese Journal of Polymer science 2000年第1期18卷 57-67页

作者： Yan Pan Rong-shi Cheng College of material science and {2., south china university of Technology, Guangzhou 510641, china College of Chemistry and Chemical {2., Nanjing university, Nanjing 2.0093, china S china Univ Technol Coll Mat Sci & Engn Guangzhou 510641 Peoples R China Nanjing Univ Coll Chem & Chem Engn Nanjing 210093 Peoples R China

The concentration dependence of the reduced viscosity of dilute polymer solution is interpreted in the light of a new concept of the self-association of polymer chains in dilute solution. The apparent self-association constant is defined as the molar association constant divided by the molar mass of individual polymer chain and is numerically interconvertible with the Huggins coefficient. The molar association constant is directly proportional to the effective hydrodynamic volume of the polymer chain in solution and is irrespective of the chain architecture. The effective hydrodynamic volume accounts for the non-spherical conformation of a short polymer chain in solution and is a product of a shape factor and hydrodynamic volume. The observed enhancement of Huggins coefficient for short chain and branched polymer is satisfactorily interpreted by the concept of self-association. The concept of self-association allows us to predict the existence of a boundary concentration C-s(dynamic contact concentration) which divides the dilute polymer solution into two regions.

关键词： self-association polymer solution viscosity concentration dependence

Surface and Electrical Properties of NiCr Thin Films Prepared by DC Magnetron Sputtering

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Journal of Wuhan university of Technology(materials {2.) 2008年第2期23卷 159-162页

作者： ZHOU Jicheng TIAN Li YAN Jianwu school of Physics science and Technology Central South University Changsha 410083 China

Several batches of NiCr alloy thin films with different thickness were prepared in a multi-targets magnetron sputtering apparatus by changing sputtering time while keeping sputtering target power of Ni and Cr fixed. Then the as-deposited films were characterized by energy-dispersive X-Ray spectrometer （EDX）, Atomic Force Microscope （AFM） and four-point probe （FPP） to measure surface grain size, roughness and sheet resistance. The film thickness was measured by Alpha-Step IQ Profilers. The thickness dependence of surface roughness, lateral grain size and resistivity was also studied. The experimental results show that the grain size increases with film thickness and the surface roughness reaches the order of nanometer at all film thickness. The as-deposited film resistivity decreases with film thickness.

关键词： magnetron sputtering NiCr alloy films surface morphology resistivity

Simulation of the Backward Flow of the Melted Pool into the Laser Keyhole

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稀有金属材料与工程 2011年第S4期40卷 35-38页

作者： Wang Hong,Huo Houzhi,Wang Lingyun school of material {2. and engineering,Taiyuan university of {2. and Technology,Taiyuan 03002.,china Taiyuan Univ Sci & Technol Sch Mat Sci & Engn Taiyuan 030024 Peoples R China

When laser beam is ceased,the melt metal flows downward to fill the keyhole during keyhole *** models and VOF(volume of fluid)techniques have been developed to study the refilling *** simulation results show that the surface tension pressure plays more important role than the total pressure of fluid flow in the molten pool,and the violent interaction between liquid metal and keyhole air and whirlpool in the fluid flow influence the dimension of keyhole air region and the velocity of molten pool.

关键词： laser welding molten pool simulation

Polycomb group proteins and their roles in carcinogenesis

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Chinese science Bulletin 2012年第18期57卷 2259-2264页

作者： XIAO LanBo 1,2.3,TAO YongGuang 1,2.3,LI LiLi 1,2.3,4 & CAO Ya 1,2.31 Key Laboratory of Carcinogenesis of Ministry of Health,Xiangya school of Medicine,central {2. university,changsha 410078,china 2.Key Laboratory of Carcinogenesis and Cancer Invasion of Ministry of Education,Xiangya school of Medicine,central {2. university,changsha 410078,china 3 Cancer Research Institute,Xiangya school of Medicine,central {2. university,changsha 410078,china 4 Cancer Epigenetics Laboratory,State Key Laboratory in Oncology in {2. china,Chinese university of Hong Kong,Hong Kong 999077,china Key Laboratory of Carcinogenesis of Ministry of Health Xiangya School of Medicine Central South University Key Laboratory of Carcinogenesis and Cancer Invasion of Ministry of Education Xiangya School of Medicine Central South University Cancer Resea

In the cell nucleus,DNA is wound around histone proteins,which are then packed together to form *** can be chemically tagged by methyl and acetyl *** group (PcG) proteins attach methyl groups to genes,which block their *** is similar to the attachment of methyl groups to gene promoters by DNA methyltransferases (DNMTs).This action is directly linked with tumor initiation and metastasis via the promotion of anti-senescence and anti-apoptosis pathways,and by facilitating epithelial mesenchymal transition (EMT).Cell fate transcriptional factors (CFTFs) and long non-coding RNAs (long ncRNAs) recruit PcG proteins to the promoters of tumor suppressor genes,resulting in epigenetic gene silencing by influencing chromatin structure and DNA ***,PcG proteins are potential diagnostic markers and targets for new chemoprevention and therapeutic strategies.

关键词：组蛋白 DNA甲基转移酶基因启动子癌变非编码RNA PEG 凋亡途径抑癌基因

Synthesis and magnetic properties of CdS/α-Fe_2._3 hierarchical nanostructures

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science china(Physics,Mechanics & Astronomy) 2009年第7期52卷 997-1002页

作者： CHEN YuJin1,2.3, SHI XiaoLing1, CAO MaoSheng1 & ZHU ChunLing4 1 school of materials {2. and engineering, Beijing Institute of Technology, Beijing 100081, china 2.Micro-Nano Technologies Research Center, Hunan university, changsha 410082. china 3 College of {2., Harbin engineering university, Harbin 150001, china 4 College of material {2. and Chemical engineering, Harbin engineering university, Harbin 150001, china 1. school of materials {2. and engineering Beijing Institute of Technology Beijing 100081 China 2. Micro-Nano Technologies Research Center Hunan University Changsha 410082 China 3. College of science Harbin Engineering University Harbin 150001 China 4. College of material science and Chemical {2. Harbin Engineering University Harbin 150001 China

CdS/α-Fe2.3 hierarchical nanostructures, where the CdS nanorods grow irregularly on the side surface of α-Fe2.3 nanorods, were synthesized via a three-step process. The diameters and lengths of CdS nanorods can be tuned by changing the ethylenediamine (EDA) and Cd ion concentrations. The magnetic investigations by superconducting quantum interference device indicate that the hierarchical nanostructures have an Morin transition at lower temperature (2.0 K) than that of the single bulk α-Fe2.3 materials (2.3 K). Importantly, the hierarchical nanostructures exhibit weakly ferromagnetic characteristics at 300 K. A sharp peak assigned to the surface trap induced emission are observed in room temperature PL spectra. Combining with the optoelectronic properties of CdS, the CdS/ α-Fe2.3 hierarchical nanostructures may be used as multi-functional materials for optoelectronic and magnetic devices.

关键词： α-Fe2.3 CdS hierarchical nanostructures magnetic properties