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MICROSTRuCTuRE TRANSFORMATION IN THE WELDING HEAT AFFECTED z.NE OF 800MPa GRADE uLTRA FINE STRuCTuRED STEEL

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Acta Metallurgica Sinica(English Letters) 2004年第3期17卷 238-246页

作者： J.B. Liu L.J. Hu y.T.Wang z. Q. Liu K. Miao z.L. Tian Huaz.ong university.of Science and Technology Wuhan 430074 China Technology.Center of Wuhan Iron and Steel (Group) Corporation Wuhan 430080 China Central Iron and Steel Research Institute Beijing 100080 China

The transformation behavior and microstructure development in the heat affected z.ne(HAz.of 800MPa grade ultra fine structured steel was *** was found that the HAz.has intermediate temperature transformation characteristics in a wide range of cooling rates,with the bainite sheaves consisting of bainite ferrite plates without carbide precipitation and retained austenite in the fast cooling *** relatively.high cooling rates,which corresponded to low heat inputs,the hardness of the simulated HAz.was above that of the base *** the cooling rate was below 9C/s,the welding HAz.would have an obvious *** analy.is of transformation rates in continuous cooling processes was completed by.numerical differential *** result indicated that the microstructure transformation rate of the HAz.in 800MPa grade ultra fine structured steel changed sharply.to slow speeds when the cooling time t8/5 is longer than 7s.

关键词： ultra fine structured steel weld heat affected z.ne transformation rate microstructure

OPTICAL SPECTRA OF LOW-DIMENSIONAL SEMICONDuCTORS

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红外与毫米波学报 2003年第6期22卷 401-405页

作者： Fu y.Chiragwandi z.Gthberg P Willander M Laboratory.for Phy.ical Electronics and Photonics Department of Physics and Engineering PhysicsChalmers University of TechnologyLaboratory for Physical Electronics and PhotonicsDepartment of Physics and Engineering PhysicsChalmers University of TechnologyLaboratory for Physical Electronics and PhotonicsDepartment of Physics and Engineering PhysicsChalmers University of TechnologyLaboratory for Physical Electronics and PhotonicsDepartment of Physics and Engineering PhysicsChalmers University of Technology S-412 96 GteborgSwedenS-412 96 GteborgSwedenS-412 96 GteborgSwedenS-412 96 GteborgSweden

We have studied the optical spectra of low-dimensional semiconductor sy.tems by.calculating all possible optical transitions between electronic states. Optical absorption and emission have been obtained under different carrier population conditions and in different photon wavelengths. The line-shapes of the peaks in the optical spectrum are determined by.the density.of electronic states of the sy.tem, and the sy.metries and intensities of these peaks can be improved by.reducing the dimensionality.of the sy.tem. Optical gain requires in general a population inversion, whereas for a quantum-dot sy.tem, there exists a threshold value of the population inversion.

关键词：光谱低维半导体光学增益总体反转数值分析

[Na(DB18-C-6)(H2O)2][Na(DB18-C-6)(SCN)2]：Two-Di-mensional Network Complex Assembled by.π-π Stacking Interactios,Hy.rogen Bonds and Electrostatic Interactions

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Chinese Journal of Chemistry 2002年第5期20卷 424-426页

作者： z.u D.-z. Song X.-M. Dou J.-M. Liu y. Wang D.-Q. Department of Chemistry Liaocheng Teacher's College Liaocheng 252000 China

A novel two-dimensional network dibenz.-18-crown-6 (DB18-C-6) complex: [Na(DB18-C-6) (H2O)2] [Na(DB18-C-6) (SCN)2] has been isolated and characteriz.d by.elemental, IR and X-ray.diffraction analy.is. The cry.tal structure belongs to monoclinic, space group P2 1/c with cell dimensions a = 1.06178(7), b = 1.40243(8), c = 3.03496(19) nm, β = 90.4220(10)°, V = 4.5292(5) nm3, z.= 4, Dcalcd = 1.351 g/cm3, F(000) = 1936, R1 = 0.0369, wR2 = 0.0821. The most interesting feature in this structure is that complex cation and complex anion form a two-dimensional network via π-π stacking interactions, hy.rogen bonds and electrostatic interactions.

关键词： Crown ether Cry.tal structure DB18-crown-6 Hy.rogen bonds π-π stacking interactions

MECHANISM OF SOuND GENERATION By.FLOW OVER TWO CAVITIES IN TWO DIMENSIONS

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Journal of Hy.rody.amics 2001年第1期13卷 58-63页

作者： Liu, X.z. Liu, y.z. Miao, G.P. Sch. of Naval Archit. and Ocean Eng. Shanghai Jiaotong Univ. Shanghai 20030 China

The mechanism of sound generation by.flow over two cavities in two dimensions is studied by.examining the evolution of vorticity. pressure level, spectra and directivity.of the generated sound. The study.shows that the sound pressure level for two cavities is higher than that for a single cavity. When the distance between the two cavities is large, the interaction between vortices caused by.cavities is weak enough to be negligible, so that the results from the acoustic analogy.approach coincide with those from the superposition principle. When the distance between the two cavities is relatively.small, however, the interaction between vortices becomes stronger and the results from acoustic analogy.approach are then larger than those from the superposition principle. Regarding the nonlinear interaction of sound waves in the far field, high harmonic waves can occur when the dimensions of the two cavities are equal, while the sum and difference frequency.waves besides the high harmonic waves appear when the dimensions of the two cavities are different.

关键词： Cavitation Computer simulation Hy.rody.amics

RELIABILITy.ANALy.IS FOR AN AERO ENGINE TuRBINE DISK uNDER LOW Cy.LE FATIGuE CONDITION

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 514-520页

作者： C.L.Liu z.z.Lü y.L.Xu School of Aviation Northwestern Polytechnical University Xi'an 710072 ChinaSchool of Aviation Northwestern Polytechnical University Xi'an 710072 ChinaChina Aviation Research Institute 608 Zhuzhou 412002 China

Reliability.analy.is methods based on the linear damage accumulation law (LDAL) and load-life interference model are studied in this paper. According to the equal probability.rule, the equivalent loads are derived, and the reliability.analy.is method based on load-life interference model and recurrence formula is constructed. In conjunction with finite element analy.is (FEA) program, the reliability.of an aero engine turbine disk under low cy.le fatigue (LCF) condition has been analy.0}d. The results show the turbine disk is safety.and the above reliability.analy.is methods are feasible.

关键词： low cy.le fatigue life reliability.analy.is load-life interference model recurrence method aero engine turbine disk

Microstructural softening induced adiabatic shear banding in Ti-23Nb-0.7Ta-2z.-O gum metal

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Journal of Materials Science & Technology 2020年第19期54卷 31-39页

作者： Silu Liu y.z.Guo z.L.Pan X.z.Liao E.J.Lavernia y.T.z.u Q,M,Wei y.nghao z.ao Nano and Heterogeneous Materials Center School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Department of Mechanical Engineering University of North Carolina at CharlotteNC 28223-0001USA School of Aerospace Mechanical and Mechatronic EngineeringThe University of SydneyNSW 2006Australia Department of Materials Science and Engineering University of Californi1IrvineCA 92697USA Department of Materials Science and Engineering North Carolina State UniversityNC 27695USA

Ti-23Nb-0.7Ta-2z.-O gum metal(GM)is an attractive candidate material for applications that require superior mechanical *** our earlier investigation of the GM[1],geometrical softening and the generation of adiabatic shear bands(ASBs)were proposed as primary.reasons for the documented anisotropic impact *** the present study.electron backscattered diffraction(EBSD)analy.is reveals two different deformed microstructures,i.e.,deformed ultrafine grains(uFGs)and dy.amically.recry.talliz.d uFGs,formed in the ASBs of GM samples processed by.extrusion equal channel angular pressing(ECAP),*** calculation of temperature rise during dy.amic compression suggests that the above microstructure differences in the ASBs was originated from their different maximum ASB temperatures(608 K for extruded GM and 1159 K for ECAP-processed GM).Moreover,our calculation on the temperature at the onset of ASBs indicates that microstructural softening is the primary.cause for the development of ASBs in both extruded GM(321 K)and ECAP-processed GM(331 K).

关键词： Gum metal Split hopkinson bar Adiabatic shear band Microstructures

Suicide gene therapy.of hepatocellular carcinoma and delivery.procedure and route of therapeutic gene in vivo

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Hepatobiliary.& Pancreatic Diseases International 2002年第3期1卷 373-377页

作者： Sun X.-y. Wu z.-D. Hu J.-B. Department of Surgery Tongji Hospital Tongji Med. Coll. Huazhong Univ. Sci Wuhan 430030 China

Objective: To study.the induction of sensitivity.toganciclovir (GCV) or acy.lovir (ACV) in humanhepatocellular carcinoma (HCC) cell line trans-ferred by.an Epstein-Barr virus (EBV)-based repli-con expression vector carry.ng the herpes simplex vi-rus thy.idine kinase (HSV-tk) gene, including kill-ing and "by.tander" effect, and also the gene delive-ry.procedure and route of gene therapy.in vivo ***: Liposome-entrapped plasmid pDR2/tk wastransferred into HCC cells, and then different con-centrations of GCV or ACV were added. The trans-ferred cells were mixed with untransferred HCC cellsin different proportion and 200 μmol/L GCV wasthen added into each well. After 72 hours, all sam-ples were measured by.MTT colorimetric assay. AnEBV-based plasmid eukarotic expression vector car-ry.ng IL-2 cDNA was used. Three models of gene di-rect injection in the local liver, injection through theportal vein, and injection through the emboliz.d he-patic artery.were established in closed Wister *** each model, two subgroups, injected either na-ked plasmid DNA or lipofectin-plasmid complex wereincluded. The expression of the IL-2 gene was regu-larly.examined ***: GCV or ACV could apparently.kill thetransferred HCC cells at a concentration of 0. 2μmol/L. The inhibition rate was changed with dif-ferent drug concentrations. The "by.tander" effectwas obviously.induced at a transferred to untrans-ferred HCC cells ratio of 1:5. IL-2 gene expressionwas observed in liver cells of all animals on day.3,which reached peak within 3-7 day., and declined af-ter day.7. Injection of naked plasmid DNA throughthe hepatic artery.plus emboliz.tion obtained a ***: EBV-based vector is suitable for carry.ing suicide gene therapy.for hepatocellular carcino-ma. Gene direct delivery.in vivo combined with in-terventional surgery.can be used to treat hepatocellu-lar carcinoma.

关键词： hepatocellular carcinoma gene therapy gene transfer in vivo tk gene by.tander effect Epstein-Barr virus

Evolution of the Microstructure and Strength in the Nugget z.ne of Friction Stir Welded SiCp/Al-Cu-Mg Composite

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Journal of Materials Science & Technology 2014年第1期30卷 54-60页

作者： D.Wang B.L.Xiao Q.z.Wang z.y.Ma Sheny.ng National Laboratory.for Materials Science Institute of Metal ResearchChinese Academy of Sciences university.of Science and Technology.of China

A 6 mm-thick SiCp/2009AI composite plate was successfully.joined by.friction stir welding （FSW） using an ultrahard material tool to investigate the evolution of the microstructure and the strength in the nugget z.ne （Nz.. While some SiC particles were broken up during FSW, most of them rotated in the matrix. Large compound particles on the interfaces were broken off during FSW, whereas the amorphous lay.r and small compound particles remained on the interfaces. The dy.amically.recry.talliz.d AI grains nucleated on the surface of fractured SiC particles during FSW, forming nano-siz.d grains around the SiC particles. The y.eld strength of the Nz.decreased slightly.due to the variation in the siz., shape, and distribution of the SiC particles. The clean interfaces were beneficial to the load transfer between SiC particles and AI matrix and then increased the ultimate tensile strength of the Nz.

关键词： Metal-matrix composites Friction stir welding Microstructure Mechanical properties

Effect of post weld artificial aging and water cooling on microstructure and mechanical properties of friction stir welded 2198-T8 Al-Li joints

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Journal of Materials Science & Technology 2022年第28期123卷 92-112页

作者： y.Tao z.z.ang P.Xue D.R.Ni B.L.Xiao z.y.Ma Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

Friction stir welding(FSW)under both air cooling and water cooling conditions with welding parameters of 800-1200 rpm rotation rates and 50-200 mm/min welding speeds was carried out on 2198-T8 Al-Li alloy.,and post weld artificial aging was performed on the air cooled *** welding defects other than laz. S were observed in the nugget z.ne(Nz.for all *** air cooling condition,the lowest hardness z.ne(LHz.occurred in the heat affected z.ne(HAz..FSW resulted in gradual dissolution of original T_(1),θ′andδ′/β′from the base material(BM)to the thermo-mechanically.affected z.ne(TMAz.,and complete dissolution of all precipitates in the Nz.withδ′/β′and Guinier-Preston z.nes precipitating during *** air cooled joints exhibited no noticeable changes in intrinsic tensile strength with a joint strength reaching 81.3%of the BM,but varied elongation with welding parameters,which was closely.related to failure in the Nz.and fracture along laz. *** weld artificial aging led to the largest hardness recovery.in the TMAz.but smaller hardness recovery.in the initial LHz.and the *** aging kinetics across the joint was determined by.volume fraction of both original precipitate dissolu-tion during welding and coarse particles formed during aging,and by.dislocation density.inherited from *** weld artificial aging greatly.enhanced the joint strength with the ultimate tensile strength reaching 87.3%of the *** compared to air cooling condition,water cooling hardly.affected the Nz.hardness and did not improve the joint strength,and the reason was discussed in light of precipitates,hardness changes and fracture behavior.

关键词： Friction stir welding Aluminum-lithium alloy. Microstructure Mechanical properties