oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 36 )

2018 ( 415 )

2017 ( 357 )

2016 ( 319 )

Custom range...

Search Results: 1 - 10 of 26194 matches for " Shiyu HE School of Materials Science and Engineering "
All listed articles are free for downloading (OA Articles)
Page 1 /26194
Display every page Item
Microstructural Evolution and Thermal Stability of Ultra-fine Grained Al-4Mg Alloy by Equal Channel Angular Pressing
Hongbin GENG,Subbong KANG,Shiyu HE,
Hongbin GENG
,Subbong KANG,Shiyu HE School of Materials Science and Engineering,Harbin Institute of Technology Harbin,China Korea Institute of Machinery and Materials,Sangnam Dong,Changwon,Kyungnam -,South Korea

材料科学技术学报 , 2004,
Abstract: Experiments were conducted to evaluate the grain refinement and thermal stability of ultra-fine grained Al-4Mg alloy introduced by equal-channel angular pressing (ECAP) at 473 K. The results show that the intensities of X-ray (111/222) and (200/400) peaks for the alloy processed by ECAP decrease significantly and the peak widths of half height become broadening compared with the corresponding value in the annealed alloy. The microstructure of 2 passes ECAPed alloy consists of both elongated and equiaxed subgrains. The residual strain in the alloy increases with increasing passes numbers, that appears as increasing dislocation density and lattice constant of matrix. An equiaxed ultra-fine grained structure of ~0.2μm is obtained in the present alloy after 8 passes. The ultra-fine grains are stable below 523 K, because the alloy retains extremely fine grain size of ~1μm after static annealing at 523 K for1 h.
INFLUENCE OF INTERFACE BETWEEN GRAIN BOUNDARY FERRITE AND PRIOR AUSTENITE ON BAINITE TRANSFORMATION IN A LOW CARBON STEEL
低碳钢中晶界铁素体/原奥氏体界面对贝氏体转变的影响

CUI Guibin,GUO Hui,YANG Shanwu,HE Xinlai School of Materials Science,Engineering,University of Science,Technology Beijing,Beijing,
崔桂彬
,郭晖,杨善武,贺信莱

金属学报 , 2009,
Abstract: The low carbon bainitic steels gain increasing attention due to their high strength, high toughness, and good weldability. To improve the toughness and weldability of this kind of steel the carbon concentration is usually deduced to below 0.06% (mass fraction). As a result the hardenability of the steel is decreased and the ferrite usually becomes the first phase formed during the cooling process before the austenite transforms to the bainite. To decrease the nucleation activation barrier the grain boundary ferrite prefers to nucleate at the prior austenite grain boundaries, which are also potential nucleation sites for the bainite. The prior austenite grain boundaries are occupied by the ferrite, meanwhile ferrite/austenite interfaces are formed, which may influence the following nucleation of bainite. To understand the effect of grain boundary ferrite/prior austenite interface on the nucleation of bainite, a low carbon Fe--C--Mn--Si steel was investigated using optical microscope and electron back--scattering diffraction (EBSD). The grain boundary ferrite and bainite were formed during the two--step isothermal holding. By combining metallographic observation with orientation measurement, two kinds of interfaces were found between grain boundary ferrite and bainitic ferrite: one is non--clear interface, and another is clear interface. The analyses show that grain boundary ferrite has nearly the K--S orientation relationship with the prior austenite on the non--clear interface side, at which bainite nucleates and grow with an orientation similar to the grain boundary ferrite, while the grain boundary ferrite has a random orientation relationship with the prior austenite on the clear interface side, and large misorientation exists between bainite and grain boundary ferrite.
FORMATION OF WHISKER AND HILLOCK IN Cu/Sn-58Bi/Cu SOLDERED JOINT DURING ELECTROMIGRATION
Cu/Sn-58Bi/Cu焊点在电迁移过程中晶须和小丘的生长

HE Hongwen,XU Guangchen,GUO Fu Beijing University of Technology,School of Materials Science,Engineering,Beijing,
何洪文
,徐广臣,郭福

金属学报 , 2009,
Abstract: With the trends of higher integration and microminiaturization in electronic packaging, the sizes of the soldered joints are becoming smaller and smaller.The corresponding current density in the soldered joints can easily reach 10~3A/cm~2 or higher,which makes the electromigration(EM) much more prominent.EM will lead to the atoms to pile up at the anode side and produce voids or cracks at the cathode side.Furthermore,with the stressing time increasing,these voids or cracks will propagate gradually resulting...
EFFECT OF Cr ADDITION ON TRANSFORMATION AND CYCLIC DEFORMATION CHARACTERISTICS OF Ti-Ni SHAPE MEMORY ALLOY
Cr掺杂对Ti-Ni形状记忆合金相变和循环形变特性的影响

YANG Jun,HE Zhirong,WANG Fang,WANG Yongshan School of Materials Science,Engineering,Shaanxi University of Technology,Hanzhong Library,Hanzhong,
杨军
,贺志荣,王芳,王永善

金属学报 , 2011,
Abstract: 使用示差扫描量热仪(DSC)和拉伸实验研究了Cr掺杂对550℃退火态Ti-50.8Ni(原子分数, %)形状记忆合金相变和循环形变特性的影响. 结果表明, Ti-50.8Ni合金冷却/加热时发生B2→R→M/M→B2型可逆相变, 掺杂0.3%Cr后所得Ti-50.8Ni-0.3Cr合金的相变类型为B2→R→M/M→R→B2, 相变温度大幅度降低. 室温下, Ti-50.8Ni和Ti-50.8Ni-0.3Cr合金的相组成均为母相B2, 前者呈现形状记忆效应, 后者呈现超弹性. 随循环变形次数n的增加, Ti-50.8Ni合金的特性由形状记忆效应演变为线性超弹性, 合金的应力诱发马氏体临界应力和积累残余应变迅速增加; Ti-50.8Ni-0.3Cr合金的特性由非完全超弹性演变为完全超弹性, 超弹性应力-应变曲线形态比较稳定. 随$n$增加, Ti-50.8Ni合金的超弹性残余应变εr减小, 超弹性应变恢复率ηs增加; Ti-50.8Ni-0.3Cr合金的εr和ηs则分别稳定在较低和较高水平, 超弹性稳定.
HOT COMPRESSION BEHAVIOR AND FLOW STRESS PREDICTION OF ZK60 MAGNESIUM ALLOY
ZK60镁合金热压缩变形流变应力行为与预测

QIN Yinjiang,PAN Qinglin,HE Yunbin,LI Wenbin,LIU Xiaoyan,FAN Xi School of Materials Science,Engineering,Central South University,Changsha,
覃银江
,潘清林,何运斌,李文斌,刘晓艳,范曦

金属学报 , 2009,
Abstract: In order to study the workability and establish the flow stress constitutive equation for ZK60 magnesium alloy, hot compressive deformation behavior of the magnesium alloy was investigated at the temperature range from 523 to 673 K and strain rate range from 0.001 to 1 s-1 on Gleeble--1500 thermal simulator. The results show that flow stress of ZK60 magnesium alloy decreases with the increase of deformation temperature and the decrease of strain rate. The flow stress curves obtained from experiments are composed of four different stages, i.e., work hardening, transition, softening and steady stages. While for the relative high temperature and low strain rate, transition stage is not very obvious. A method to predict flow stress considering the effect of true strain was presented. Flow stress model is expressed by nine independent parameters and they are obtained by Least--Square method. The predicted stress--strain curves are in good agreement with the experimental results, which confirmed that the developed model can give a reasonable estimate of the flow stress for ZK60 magnesium alloy.
MORPHOLOGY AND SUBSTRUCTURE OF JUJUBE-STONE-LIKE MARTENSITE IN ULTRAHIGH CARBON STEEL
超高碳钢中枣核状马氏体形态及亚结构

ZHANG Zhanling School of Materials Science,Engineering,Henan University of Science,Technology,Luoyang LIU Yongning,YU Guang,ZHU Jiewu,HE Tao State Key Laboratory for Mechanical Behavior of Materials,Xi''an Jiaotong University,Xi''an,
张占领
,柳永宁,于光,朱杰武,何涛

金属学报 , 2009,
Abstract: In the martensitic transformation of an ultrahigh carbon steel (UHCS) containing 1.58%C, a kind of jujube-stone-like martensite has been observed in addition to lath and twinning martensites. The substructure of the jujube-stone-like martensite is high density dislocation with 1013/cm2 and no twin has been found. Theoretical analysis based on a disc-like martensite grain shows that the strain energy is not relative to the critical thickness of the disc (2t0*) but relative to the critical diameter of the disc (2r0*), and the critical nucleation energy ΔG* is inversely related to the square of the critical aspect ratio, t0*/r0*, of martensitic grains. When t0*/r0*<1, martensitic nucleus is disc shape, t0*/r0*>1, the nucleus is jujube--stone--like and t0*/r0*>>1, the nucleus is rod shape.
Effect of Nb on Structure and Mechanical Properties of Chilled Cast Iron at Room and Elevated Temperatures
Qijie ZHAI,Li FU,Huaying ZHAI,
Qijie ZHAI
,Li FU,Huaying ZHAI School of Materials Science and Engineering,Shanghai University,Shanghai,China School of Materials Science and Engineering,Shenyang University,Shenyang,China School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing,China

材料科学技术学报 , 2004,
Abstract: Effect of Nb on microstructure and mechanical properties of chilled cast iron at room and elevated temperatures is studied in this research. The results demonstrate that the cast structure and mechanical properties of chilled cast iron at room and elevated temperatures are improved with the addition of trace amount of Nb. However, if Nb was added too much, the cast structure and mechanical properties of chilled cast iron would deteriorate. The suitable content of Nb in chilled cast iron is about 0.05% (mass fraction). Except the dissolution in the matrix of cast iron the excessive Nb will form Nb-rich phases in three morphologies. Those are lumpy NbC, complicated strip-like phase and compound with pearlite structure.
A TRANSPARENT COATINGS FOR COPPER SURFACE PROTECTION
铜表面透明防蚀封护剂的研究

XU Chun-chun,YU Miao,WANG Ju-ling,HE Zong-hu School of Materials Science,Engineering,Beijing University of Chemical Technology,Beijing,
许淳淳
,于淼,王菊琳,何宗虎北京化工大学材料科学与工程学院

腐蚀科学与防护技术 , 2004,
Abstract: Protective coatings for copper alloy were prepared using acrylic resin emulsion modified by nanometer TiO_2 and corrosion inhibitor Benzotriazole(BTA).Electrochemical impendance spectroscopy(EIS),ultraviolet spectroscopy,salt fog test,chemical resistance,water proofness and mechanical performances were all employed to study its properties.Results showed that the coatings have excellent performances and can protect copper alloy effectively.Anti-ultraviolet aging ability of coatings is improved effectively by adding nanometer TiO_2.The coating is achromic,transparent,non-toxic and odorless.It's friendly to environment.
FATIGUE FEATURES AND MECHANISM OF Al-7Si-0.3Mg CAST ALLOY UNDER NONPROPORTIONAL LOADINGS
非比例载荷下Al-7Si-0.3Mg合金的循环特性及微观机理

MO Defeng,HE Guoqiu,ZHU Zhengyu,LIU Xiaoshan School of Materials Science,Engineering,Tongji University,Shanghai ZHANG Weihua State Key Laboratory of Traction Power,Southwest Jiaotong University,Chengdu,
莫德锋
,何国球,朱正宇,刘晓山,张卫华

金属学报 , 2009,
Abstract: Widely application of cast aluminum alloy requires an understanding of its cyclic deformation behavior which is material dependent, and it is a complex function of strain amplitude, loading path, etc. In this study, multi--axial fatigue tests were conducted on cast Al--7Si--0.3Mg alloy with the same equivalent strain amplitude of 0.22% under six multi--axial path loadings, which were proportional, circular, square, diamond, rectangle and ellipse paths. TEM was employed to investigate the dislocation structures of the fatigue failure specimens. Cyclic hardening dominates the whole fatigue process under every loading path, but the rate and extent of cyclic hardening are quite dependent on particular loading paths. The fatigue life under nonproportional loading is much lower than that under proportional loading, and it also depends on the various nonproportional loading paths. The specimen with circular path loading has the shortest life and the most severe cyclic hardening among all the loading paths. The continuously changing of direction of maximum shear--stress plane is attributed to the complicated dislocation substructures and severe stress concentration during the cyclic process. The interaction among dislocation, particle and cell boundary is the main reason for cyclic hardening. The structure and density of dislocation in fatigue failure specimens under various loading paths exhibit quite different. From double dislocation bands, multiple dislocation bands, labyrinth structure to cell structure, the dislocation mobility decreases and stress concentration degree increases.
OXIDATION BEHAVIOR OF KOVAR ALLOY IN CONTROLLED ATMOSPHERE

DW Luo,ZS Shen School of Materials Science,Engineering,University of Science,Technology Beijing,Beijing,China,

金属学报(英文版) , 2008,
Abstract: Controlled oxidation experiments were performed on Kovar alloy by changing oxi-dation atmosphere, temperature, and exposure time to produce films with different oxide type and thickness. The results indicated that single Fe3O4 and single FeO were respectively obtained when Kovar alloy was oxidized in N2-2.31%H2O-0.95%H2 at 500℃ and in N2-2.31%H2O-O.5%H2 at 1000℃, and all kinetic curves followed linear relation; mixed oxides of FeO and Fe3O4 formed when Kovar was oxidized in N2-2.31%H2O at 1000℃, and parabolic kinetics were obeyed. Analysis of metal-lographic cross section of oxides indicated that oxygen diffusion inward through the oxide scale is responsible for intergranular oxide, which had formed beneath the oxide scales when the oxide products were mixed oxides of FeO and Fe3O4, and which did not occur when the oxide was single FeO or Fe3O4. The oxidation model was also established.
Page 1 /26194
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.