检索结果-南通市图书馆

Journal of Materials Science & Technology 2013年第12期29卷 1116-1122页

作者： z.A.luo G.M.Xie z.Y.Ma G.l.Wang G.D.Wang State Key laboratory of Rolling and Automation Northeastern University Shenyang National laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

As-extruded zK60 and zK60-Y magnesium alloy plates were successfully processed via friction stir processing （FSP） at a tool rotation rate of 1600 r/rain and a traverse speed of 200 mm/min. FSP resulted in the formation of equiaxed recrystallized microstructures with the average grain sizes of ,-8.5 and -4.7 μm in the zK60 and zK60-Y alloys, respectively. Moreover, FSP broke and dispersed the Mgzn2 and W-phase （Mg3zn3Y2） particles and dissolved Mgzn2 phase in the FSP zK60 alloy. With the addition of rare earth element yttrium （Y） into the zK60 alloy, the ratio of the high angle grain boundaries （HAGBs） in the FSP alloys increased from 64% to 90%, and a certain amount of twins appeared in the FSP zK60-Y alloy. The maximum elongation of 1200% and optimum strain rate of 3 X 10-3 s-1 achieved at 450 °C in the FSP zK60-Y alloy were substantially higher than those of the FSP zK60 alloy. This is attributed to the fine grains with high ratio of HAGBs and the distribution of a large number of dispersed second phase particles with high thermal stability in the FSP zK60-Y alloy. Grain boundary sliding was identified as the primary deformation mechanism in the FSP zK60 and zK60-Y alloys from the superplastic data analyses and surficial morphology observations.

关键词： Magnesium alloy Friction stir processing Rare earth element Microstructure Superplasticity

Magneto optics and time resolved terahertz spectrocopy

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2018年第7期27卷 112-119页

作者： T Dong z G Chen N l Wang International Center for Quantum Materials School of PhysicsPeking UniversityBeijing 100871China Institute of Physics Chinese Academy of SciencesBeijing 100190China

Exploring, manipulating, and understanding new exotic quantum phenomena in condensed-matter systems have gen- erated great interest in the scientific community. Static and time resolved optical spectroscopies after photoexcitations are important experimental tools for probing charge dynamics and quasiparticle excitations in quantum materials. In Syner- getic Extreme Condition User Facility （SECUF）, we shall construct magneto-infrared and terahertz measurement systems and develop a number of ultrafast femtosecond laser based systems, including intense near to mid-infrared pump terahertz probe. In this article, we shall describe several systems to be constructed and developed in the facilities, then present some examples explaining the application of magneto optics and time resolved spectroscopy techniques.

关键词： magneto-optics infrared spectroscopy mid-infrared pump terahertz probe

Mechanical Properties of a low-thermal-expansion Aluminum/Silicon Composite Produced by Powder Metallurgy

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2014年第4期30卷 417-422页

作者： Y.Q.liu S.H.Wei J.z.Fan z.l.Ma T.zuo National Engineering & Technology Research Center for Nonferrous Metal Matrix Composites Beijing General Research Institute for Nonferrous Metals

AI matrix composite containing high volume fraction silicon has been promising candidate for lightweight and low-thermal-expansion components. Whereas, optimization of its mechanical properties still is an open challenge. In this article, a flexile powder metallurgy processing was used to produce a fully dense AI-4.0Cu （wt%） alloy composite reinforced with 65 vol.% Si particles. In this composite, Si particles were homogenously distributed, and the particle size was refined to the range of 3-15 μm. Tensile and flexural strength of the composite were 282 and 455 MPa, respectively, about 100% and 50% higher than the best properties reported in literature. The measured fracture toughness of the composite was 4.90 MPa m1/2. The improved strength of 65%Si/AI was attributed to the optimized particle characteristics and matrix properties. This investigation is expected to provide a primary understanding of the mechanical behaviors of Si/AI composites, and also promote the structural applications of this low-thermal-expansion material.

关键词： Aluminum matrix composite Powder metallurgy Mechanical properties Coefficient of thermal expansion Fracture

Spectral measurements of hypervelocity flow in an expansion tunnel

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2019年第1期35卷 24-31,I0002页

作者： C.K.Yuan K.zhou Y.F.liu z.M.Hu z.l.Jiang State Key laboratory of High-Temperature Gas Dynamic Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Sciences. University of Chinese Academy of Sciences Beijing 100049China China Academy of Aerospace Aerodynamics Beijing 100074China

Atmospheric reentry vehicles and planetary probes fly through the atmosphere at hypervelocity speed. At such speed, there is a significant proportion of heat load to the vehicle surface due to radiative heating. Accurate prediction needs a good knowledge of the radiation spectrum properties. In this paper, a high-speed camera and spectrograph coupled to an intensified charge-coupled device have bee n impleme nted to inv estigate the rad i at io n flow over a semi-cylinder model. The experiments were carried out in the JF16 expansi on timnel with secondary shock velocity of 7.9 km·s^-1. Results show that the emissio n spectrum comprises several atomic lines and molecular band systems. We give detailed data of the radiation spectrum, shock shape, shock detached distance and radiation intensity varying with space and wavelength. This valuable experimental dataset will be helpful to validate computational fluid dynamics codes and radiation models, which equates to increased prediction accuracy of radiation heating. Also, some suggestions for spectral measurement in hypervelocity flow field were list in the end.

关键词： Spectral measurement Hypervelocity flow Radiation Expansion tunnel

Basic features of the multiscale interaction between tearing modes and slab ion-temperature-gradient modes

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2019年第12期28卷 237-247页

作者： l Wei z X Wang J Q li z Q Hu Y Kishimoto Key laboratory of Materials Modification by laser Ionand Electron Beams(Ministry of Education)School of PhysicsDalian University of TechnologyDalian 116024China Southwestern Institute of Physics Chengdu 610041China Graduate School of Energy Science Kyoto UniversityGokashoUjiKyoto 1-0011Japan

Nonlinear interaction between tearing modes(TM) and slab ion-temperature-gradient(ITG) modes is numerically investigated by using a landau fluid model. It is observed that the energy spectra with respect to wavenumbers become broader during the transition phase from the ITG-dominated stage to TM-dominated stage. Accompanied with the fast growth of the magnetic island, the frequency of TM/ITG with long/short wavelength fluctuations in the electron/ion diamagnetic direction decreases/increases respectively. The decrease of TM frequency is identified to result from the effect of the profile flattening in the vicinity of the magnetic island, while the increase of the frequencies of ITG fluctuations is due to the eigenmode transition of ITG induced by the large scale zonal flow and zonal current related to TM. Roles of zonal current induced by the ITG fluctuations in the instability of TM are also analyzed. Finally, the electromagnetic transport features in the vicinity of the magnetic island are discussed.

关键词： magnetic reconnection tearing modes magnetohydrodynamics drift waves nonlinear phenomena

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

在线全文

学校读者我要写书评

暂无评论

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

作者： Y.Tao z.zhang 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 alloys,and post weld artificial aging was performed on the air cooled *** welding defects other than lazy S were observed in the nugget zone(Nz)for all *** air cooling condition,the lowest hardness zone(lHz)occurred in the heat affected zone(HAz).FSW resulted in gradual dissolution of original T_(1),θ′andδ′/β′from the base material(BM)to the thermo-mechanically affected zone(TMAz),and complete dissolution of all precipitates in the Nz withδ′/β′and Guinier-Preston zones 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 lazy *** 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 alloys Microstructure Mechanical properties

Role of seed size, phenology, oogenesis and host distribution in the specificity and genetic structure of seed weevils (Curculio spp.) in mixed forests

在线全文

学校读者我要写书评

暂无评论

Integrative zoology 2018年第3期13卷 267-279页

作者： Harold ARIAS-lEClAIRE Raúl BONAl daniel GARCÍA-lÓPEz Josep Maria ESPElTA CREAF Centre for Ecological Research and Forestry ApplicationsCerdanyola del Vallès08193Spain Exact and Natural Sciences School State Distance University of Costa RicaUNEDMercedes de Montes de OcaSan JoséCosta Rica Forest Research Group INDEHESAUniversity of ExtremaduraPlasenciaSpain DITEG Research Group University of Castilla-La ManchaToledoSpain zoology Department Autonomous University of BarcelonaCerdanyola del VallèsSpain

Synchrony between seed growth and oogenesis is suggested to largely shape trophic breadth of seed-feeding insects and ultimately to contribute to their co-existence by means of resource partitioning or in the time when infestation *** we investigated:(i)the role of seed phenology and sexual maturation of females in the host specificity of seed-feeding weevils(Curculio spp.)predating in hazel and oak mixed forests;and(ii)the consequences that trophic breadth and host distribution have in the genetic structure of the weevil *** analyses were used to establish unequivocally host specificity and to determine the population genetic *** identified 4 species with different specificity,namely Curculio nucum females matured earlier and infested a unique host(hazelnuts,Corylus avellana)while 3 species(Curculio venosus,Curculio glandium and Curculio elephas)predated upon the acorns of the 2 oaks(Quercus ilex and Quercus pubescens).The high specificity of *** coupled with a more discontinuous distribution of hazel trees resulted in a significant genetic structure among *** addition,the presence of an excess of local rare haplotypes indicated that *** populations went through genetic expansion after recent ***,these effects were not observed in the more generalist Curculio glandium predating upon ***,co-existence of weevil species in this multi-host-parasite system is influenced by both resource and time *** what extent the restriction in gene flow among *** populations may have negative consequences for their persistence in a time of increasing disturbances(*** in Mediterranean areas)deserves further research.

关键词： Corylus avellana Curculio spp. genetic structure Quercus spp. trophic breadth

Tailoring precipitation/properties and related mechanisms for a high-strength aluminum alloy plate via low-temperature retrogression and re-aging processes

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第25期120卷 15-35页

作者： l.G.Hou H.Yu Y.W.Wang l.You z.B.He C.M.Wu D.G.Eskin l.Katgerman l.z.zhuang J.S.zhang State Key laboratory for Advanced Metals&Materials University of Science&Technology BeijingBeijing 100083China BCAST Brunel University LondonKingston LaneUxbidge Middlesex UB83PHUnited Kingdom Institute of mineral resources Chinese Academy of Geological SciencesBeijing 100037China Nanjing Advanced Transportation Equipment New Technology Research Institute Nanjing 211800China Tomsk State University Tomsk634050Russian Federation Katgerman Aluminium Technology van Beuningenlaan 102334CC LeidenNetherlands Department of Materials Science and Engineering Delft University of TechnologyMekelweg 22628CD Delftthe Netherlands

The retrogression and re-aging(RRA)processes,aimed mainly at tailoring intergranular precipitates,could significantly improve the corrosion resistance(i.e.,stress corrosion cracking resistance)without considerably decreasing the strength,which signifies that an efficient control of the size,distribution and evolution of intergranular and intragranular precipitates becomes critical for the integrated properties of the(mid-)thick high-strength Al alloy *** to RRA process with retrogression at200℃ (T77),this study investigated the impact of a modified RRA process(MT77)with lower retrogression temperatures(155-175℃ )and first-stage under-aging on the properties of a high-strength AA7050 Al alloy,in combination with detailed precipitate *** study showed that the strength/microhardness of the RRA-treated alloys decreased with raising retrogression temperature and/or prolonging retrogression time,along with the increased electrical *** rapid responsiveness of microstructure/property typical of retrogression at 200℃ was obviously postponed or decreased by using MT77 process with longer retrogression time that was more suitable for treating the(mid-)thick *** the other hand,higher retrogression temperature facilitated more intragranularηprecipitates,coarse intergranular precipitates and wide precipitate free zones,which prominently increased the electrical conductivity alongside a considerable strength loss as compared to the MT77-treated *** the preferred MT77 process,the high strength approaching T6 level as well as good corrosion resistance was ***,though a relatively homogeneous through-thickness strength was obtained,some small discrepancies of properties between the central and surface areas of an 86-mm thick 7050 Al alloy plate were observed,possibly related to the quenching *** precipitate evolution and mechanistic connection to the properties were discussed and reviewed for high-strengt

关键词： Aluminum alloy Heat treatment Precipitation Strength Grain boundary

An On-line Galvanic Cell Generated Electrochemiluminescence and Flow Injection Determination of Calcium in Milk and Vegetable

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical letters 2003年第6期14卷 599-602页

作者： luo l.R. lü J.G. zhang z.J. Department of Chemistry Shaanxi Normal University Xi'an 710062 China

An on-line Ag/Al galvanic cell is investigated and employed to generate electrochemiluminescence (ECl). The potential of the galvanic cell could be adjusted by varying the components of flow reagent. The cell performed perfect capability of supplying a stable potential for ECl generation. Based on the weak ECl of calcein blue could be greatly sensitized by the presence of calcium in alkaline solution, calcium contents in milk samples and in cabbage were assayed and the results were compared with those from ICP-AES method.

关键词： On-line galvanic cell electrochemiluminescence calcium.

Different Diffusion Behavior of Cu and Ni Undergoing liquidesolid Electromigration

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2014年第12期30卷 1235-1242页

作者： M.l.Huang z.J.zhang H.T.Ma l.D.Chen Electronic Packaging Materials laboratory School of Materials Science & Engineering Dalian University of Technology IC Packaging Department Xi'an Institute of Microelectronic Technology

The diffusion behavior of Cu and Ni atoms undergoing liquidesolid electromigration（l-S EM） was investigated using Cu/Sn/Ni interconnects under a current density of 5.0 103A/cm2 at 250℃. The flowing direction of electrons significantly influences the cross-solder interaction of Cu and Ni atoms, i.e., under downwind diffusion, both Cu and Ni atoms can diffuse to the opposite interfaces; while under upwind diffusion,Cu atoms but not Ni atoms can diffuse to the opposite interface. When electrons flow from the Cu to the Ni, only Cu atoms diffuse to the opposite anode Ni interface, resulting in the transformation of interfacial intermetallic compound（IMC） from Ni3Sn4into（Cu,Ni）6Sn5and further into [（Cu,Ni）6Sn5t Cu6Sn5], while no Ni atoms diffuse to the opposite cathode Cu interface and thus the interfacial Cu6Sn5 *** electrons flow from the Ni to the Cu, both Cu and Ni atoms diffuse to the opposite interfaces,resulting in the interfacial IMC transformation from initial Cu6Sn5into（Cu,Ni）6Sn5and further into[（Cu,Ni）6Sn5t（Ni,Cu）3Sn4] at the anode Cu interface while that from initial Ni3Sn4into（Cu,Ni）6Sn5and further into（Ni,Cu）3Sn4at the cathode Ni interface. It is more damaging with electrons flowing from the Cu to the Ni than the other way.

关键词： Cu/Sn/Ni Electromigration Cross-solder interaction Interfacial reaction Diffusion