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A study on compressive shock wave propagation in metallic foams

Science china(Physics,Mechanics & Astronomy) 2010年第2期53卷 279-287页

作者： WANG ZhiHua1,2.ZHANG YiFen2.REN HuiLan1 & ZHAO LongMao2.1 state key {2. of Explosion Science and Technology,Beijing Institute of Technology,Beijing 100081,china 2.Institute of Applied Mechanics and Biomedical Engineering,Taiyuan university of Technology,Taiyuan 03002.,china 1. state key {2. of Explosion Science and Technology Beijing Institute of Technology Beijing 100081 China2. Institute of Applied Mechanics and Biomedical Engineering Taiyuan University of Technology Taiyuan 030024 China

metallic foam can dissipate a large amount of energy due to its relatively long stress plateau,which makes it widely applicable in the design of structural crashworthiness. However,in some experimental studies,stress enhancement has been observed when the specimens are subjected to intense impact loads,leading to severe damage to the objects being protected. This paper studies this phenomenon on a 2. mass-spring-bar model. With the model,a constitutive relationship of metal foam and corresponding loading and unloading criteria are presented; a nonlinear kinematics equilibrium equation is derived,where an explicit integra-tion algorithm is used to calculate the characteristic of the compressive shock wave propagation within the metallic foam; the effect of heterogeneous distribution of foam microstructures on the shock wave features is also included. The results reveal that under low impact pulses,considerable energy is dissipated during the progressive collapse of foam cells,which then reduces the crush of objects. When the pulse is sufficiently high,on the other hand,stress enhancement may take place,especially in the heterogeneous foams,where high peak stresses usually occur. The characteristics of compressive shock wave propagation in the foam and the magnitude and location of the peak stress produced are strongly dependent on the mechanical properties of the foam material,amplitude and period of the pulse,as well as the homogeneity of the microstructures. This research provides valuable insight into the reliability of the metallic foams used as a protective structure.

关键词： aluminum foam heterogeneous intensive pulse loading stress enhancement

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锗/硅异质纳米结构中空穴存储特性研究

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物理学报 2004年第4期53卷 1211-1216页

作者：杨红官施毅闾锦濮林张荣郑有炓南京大学物理系固体微结构物理国家重点实验室南京210093

对p沟道锗硅异质纳米结构存储器空穴隧穿的物理过程作了详细的分析 ,并对器件的擦写和保留时间特性进行了数值模拟 .研究结果表明 :由于异质纳米结构的台阶状隧穿势垒和较高价带带边差的影响 ,与传统的硅纳米结构存储器和n沟道锗硅... 详细信息

对p沟道锗硅异质纳米结构存储器空穴隧穿的物理过程作了详细的分析 ,并对器件的擦写和保留时间特性进行了数值模拟 .研究结果表明 :由于异质纳米结构的台阶状隧穿势垒和较高价带带边差的影响 ,与传统的硅纳米结构存储器和n沟道锗硅异质纳米结构存储器相比 ,当前器件的保留时间分别提高到 10 8和 10 5 s以上 ,同时器件的擦写时间特性基本保持不变 .这种存储器结构单元有效地解决了快速擦写编程和长久存储之间的矛盾。

关键词：锗/硅异质结纳米结构存储器空穴存储数值模拟隧穿势垒器件结构

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The Impact of Annealing Temperature on the Optical Performance of Cr-Cr_2._3 Produced by Plasma Spraying as Solar Energy Selective Absorber Coating

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稀有金属材料与工程 2012年第S1期41卷 315-318页

作者： Gong Dianqing,Cheng Xudong,Wang Ke state key {2. of Advanced Technology for Materials Synthesis and Processing,Wuhan university of Technology,Wuhan 430070,china Wuhan Univ Technol State Key Lab Adv Technol Mat Synth & Proc Wuhan 430070 Peoples R China

A series of selective solar absorber coatings of Cr-Cr2.3 were deposited in different content on stainless steel by plasma *** samples were annealed at different *** optical performance(both the solar absorptance and the thermal emittance)were studied by *** surface morphology,the structure and the surface roughness were investigated by scanning electron microscopy(SEM),X-ray diffraction(XRD),and roughmeter *** results show that,as the content of Cr increased,the solar absorptance(α)decreased greatly,from 0.91 to ***,the thermal emittance(ε) decreased more greatly,from 0.86 to about *** ratio between the solar absorptance and the thermal emittance increased from 1.06 to *** had a great impact on the optical *** temperature is an important *** its influence was a little *** pure Cr coating,annealing at 500℃ was a perfect chosen,where the ratio between the solar absorptance and the thermal emittance was highest of 1.46.

关键词： optical performance plasma spraying solar energy selective absorber coating

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Influence of Welding Thermal Cycle on Microstructure and Properties in Heat-affected Zone of X80 Pipeline Steel

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稀有金属材料与工程 2011年第S3期40卷 123-127页

作者： Deng Wei, Gao Xiuhua, Qin Xiaomei, Zhao Dewen, Du Linxiu state key {2. of Rolling and Automation, Northeastern university, Shenyang 110819, china Northeastern Univ State Key Lab Rolling & Automat Shenyang 110819 Peoples R China

Single welding thermal–cycles with different input linear energies (ILE)(15, 2., 30, 40, 50 kJ/cm) and peak temperatures (PT) (900, 1050, 12.0, 1300, 1350 ℃) were simulated by MMS-300 to study the correlation of toughness and microstructure in heat-affected zone (HAZ) of a X80 pipeline. The evolution characteristics of microstructure were investigated by OM, SEM and EBSD. The results show that numerous polygonal ferrites and grain boundary ferrites appear, and the sizes apparently decrease as the heat input decreases. Heat input in single welding should be less than 35 kJ/cm to ensure well Charpy impact toughness. The toughness of course grain zone is the lowest when welding heating temperature is 1350 ℃ and it is the weakness part in welded zone. The uniformity of prior austenite grain is worsened as increasing the heat input. Moreover, the characteristics of M-A constituents and high angle grain boundaries (HAGB) are influenced by heat input and PT. In the case of low heat input and PT, higher density of HAGBs, dispersed and fine M-A constituents were observed. Otherwise, with high heat input (≥40 kJ/cm), the effective grain size is almost the diameter of prior austenite grain, and it will decrease the density of HAGB, moreover, coarse M-A constituents which are prone to crack initiation will be generated, thus, the impact toughness of the coarse grain zone will be worsened obviously in welding HAZ.

关键词： X80 pipeline steel welding simulation heat-affected zone impact toughness

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EFFECT OF ORIENTATION ON STRESS RESPONSE,FRICTION STRESS AND BACK STRESS DURING CYCLIC DEFORMATION IN Al SINGLE CRYSTALS

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Acta metallurgica Sinica(English Letters) 1993年第1期6卷 67-72页

作者： XIA Yuebo ZHANG Tianyi state key {2. for Fracture and Failure of Materials.Institute of metal research,Academia Sinica.Shenyang.china DENG Jun Shenyang Polytechnical university.china Associate Professor,Institute of metal research,Academia Sinica,Shenyang 110015,china

The symmetrical push-pull fatigue tests at strain amplitude of 2.10~3 with different slip orientation of Al single crystals,were carried out at room temperature in *** peak stresses of various cycles were measured an... 详细信息

关键词： crystal orientation cyclic deformarion stress response energy loss slip morphology

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Deformation-induced α_2.γ Interfaces in a Hot-deformed Ti-45Al-10Nb Alloy

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Journal of Materials Science & Technology 1998年第2期14卷 132-138页

作者： Jinguo WANG Lichun ZHANG and Guoliang CHEN (state key Lab. for Advanced {2.s and Materials, university of Science and Technology Beijing, Beijing 100083, china )Henqiang YE(Lab. of Atomic Imaging of Solids, Institute of {2. research, Chinese Academy state key Lab. for Advanced {2.s and Materials University of Science and Technology Beijing Beijing 100083 China Lab. of Atomic Imaging of Solids Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China

The structure change of α2.γ interface in a Ti-45Al-10Nb alloy induced by hot deformation was investigated by conventional and high-resolution transmission eIectron microscopy. Two types of hot deformation induced special α2.γ intedeces, coherent intedeces with high density of ledges and semi-coherent α2.γ intedeces were found to be due to the absorption of mobile dislocations into the α2.γ inteface. For the misoriented semi-coherent α2.γ interfaces, the densities of dislocation ledges increase with the misoriented angle between (111)γ and (0001)α2.planes, and 1/3[111] Frank partial dislocations were involved in the dislocation ledges. Formation mechanism of these deformation-induced α2.γ interfaces was discussed to be related to the role of α2.γ interface5 adjusting the deformation as a dislocation sink absorbing the slipping dislocations in the γ phase

关键词： Al Ti Interfaces in a Hot-deformed Ti-45Al-10Nb Alloy Deformation-induced

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Phase Relations in TiAl+Nb System

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Journal of Materials Science & Technology 1994年第5期10卷 359-366页

作者： Jingguo WANG Guoliang CHEN and Zuqing SUN (state key Lab. for Advanced {2. Materials, university of Science and Technology Beijing, Beijing, 100083, china)Hengqiang YE (Lab. of Atomic Imaging of Solids, Institute of {2. research, Academia Sinica, Sh Univ of Science and Technology Beijing China

The microstructures and phases of ternary TiAl+Nb alloys containing 50-60 at.-%Al, 0-2. at.-%Nb have been studied using transmission electron microscopy (TEM) and X-ray powder diffraction. The phases present in the alloys and their distribution were found to be a sensitive function of composition. The phase relations between γ-TiAl and γ1 (a new ordered ternary intermetallic compound based on γ-TiAl) were determined. Essentially single γ phase was determined for alloys with relativety low Nb content (≤10 at.-%Nb). the γ1 phase was determined to exist in the composition range containing higher Nb contents (15-2. at.-%Nb). Between γ and γ1 phases, with intermediate Nb contents there is a transitional phase γ1 (a superstructure of γ-TiAl). As for the influence of Al concentration on the phase relations. the γ1 phase was inclined to form in the alloys with relatively high Al contents. The ordering transformation of γ, to γ1 is a continuous ordering process and the transition may be second order.

关键词： TiAl nm PA Phase Relations in TiAl+Nb System Chen

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Fabrication and properties of binder for powder extrusion molding

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Rare metals 2003年第2期22卷 98-102页

作者： ZHOUJicheng HUANGBaiyun SchoolofPhysicsScienceandTechnology CentralSouthUniversityChangsha410083China statekey{2.forPowdermetallurgy CentralSouthUniversityChangsha410083China

By optimizing formulation and fabrication methods, a new binder forplasticizing powder extrusion molding of hard metal, with excellent integrated properties anduniform distribution characters, has been developed. Thermal debonding mechanism and the extrudingtheological behaviours have been studied. The technology of fabrication of binder and thermaldebonding process have also been investigated. Using the novel binder, the hard-metalextrusion-molding rods with diameter up to 2.mm, have been manufactured.

关键词： powder metallurgy binder powder extrusion molding thermal debonding rheology hard metal

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STRAIN　INDUCED　STRUCTURAL　TRANSITION　OF　INTERFACES　AND　TWINS　IN　A　HOT－DEFORMED　DUAL－PHASE　TIAL　ALLOY

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Acta metallurgica Sinica(English Letters) 1995年第Z1期8卷 273-286页

作者： CHEN GuoFiang WANG Jinguo ZHANG Lichun and YE Hengqiang(state key {2. for Advanced metals and Materials, university of Science and Technology Beijing, Beijing, 100083, P. R. china {2. of Atomic Imaging of Solids, Institute of metal Researc Beijing Univ of Science and Technology Beijing China

The structure characteristics of a2.γinterfaces and the features of deformation twins in a quasi-isothermal forged Ti-45Al-10Nb alloy were studied by highresolution transmission electron microscopy. Three types of strain induced a2.γinterfaces and two types of strain induced twin boundaries were identified The most,important features are high density of ledges and the existence of I/3[111] Frank partial dislocation. Mechanisms for the formation these interfaces were proposed Two types of deformation twins were observed These deformation twins always start from the ledges it seems that ledges at interfaces are important features of interfacial structure for the mechanical behavior of alloys.

关键词： strain induced structural transition interfacial structure,deformation twins intermetallic TiAl alloy HREM

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X-ray Study on the Ring-substituted Phthalocyanines:Crystal Structure of metal Free 1,4,8,11,15,18,2.,2.-Octa-butyloxyphthalocyanine

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Chinese Journal of Structural Chemistry 2002年第6期21卷 617-620页

作者： WANG Jun-Dong HUANG Jin-LingCAI Jin-Wan CHEN Nai-Sheng(Department of Chemistry, Fuzhou university, and state {2. laboratory of Structural Chemistry,Fuzhou 350002. china) Department of Chemistry Fuzhou University State Key Laboratory of Structural Chemistry Fuzhou 350002

The crystal structure of 1,4,8,11,15,18,2.,2.-octa-butyloxyphthalocyanine was determined by X-ray diffraction methods. The crystal is of triclinic, space group P 1 with a = 14.0780(3), b = 14.3480(4), c = 17.0090(2. A, α = 72.156(2., β = 86.193(2., r= 73.655(2.°, C64H82.8O8, Mr = 1091.38, Z = 2. V = 3137.5(1) A3, Dc= 1.155 g/cm3, F(000) = 1172. μ(MoKα) = 0.077 mm-1, the final R = 0.0787 and wR = 0.2.40 for 5795 observed reflections with I ≥ 2.(I). The steric congestion between the neighboring butyloxy groups distorts the core of phthalocyanine into a saddle shape conformation. In the crystal lattice, molecules overlap to each other with π-π interaction but the extent of overlap is different along the three axial directions.

关键词： phthalocyanine crystal structure

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