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Nanostructured Ti29.7Ni50.3Hf20 high temperature shape memory alloy processed by high-pressure torsion

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Journal of Materials Science & Technology 2020年第17期52卷 218-225页

作者： A.Shuitcev D.V.Gunderov b.Sun L.Li R.Z.Valiev Y.X.Tong Institute of Materials Processing and Intelligent Manufacturing College of Materials Science and Chemical EngineeringHarbin Engineering UniversityHarbin150001China Institute of Physics of Advanced Materials Ufa State Technical University of AviationUfa450000Russia Center of Testing and Analysis College of Materials Science and Chemical EngineeringHarbin Engineering UniversityHarbin150001China Laboratory for Mechanics of Advanced bulk Nanomaterials for Innovative Engineering Applications Saint-Petersburg State UniversitySaint-Petersburg199034Russia

High-pressure torsion(HPT)processing under a pressure of 6.0 GPa was applied to Ti29.7Ni50.3Hf20(at.%)*** types of structure were observed after HPT with 3 revolutions:first one is the mixture of amorphous phase and retained nanocrystalline;second is the alternating bands of amorphous phase and high defect density *** a result,post deformation annealing(PDA)at 500-700℃leads to the non-uniform distribution of martensite and parent phase *** grains of martensite are twice larger compared to that of parent *** nanocrystalline and ultrafine grains form after annealing at 500-600℃and 700℃,*** twinning mechanism does not change with the reduction of martensitic grains up to^35 *** relationship between strength and grain size in Ti29.7Ni50.3Hf20 alloy obeys the classical Hall-Petch relationship with a coefficient of 10.80±0.39 GPa nm^1/2.

关键词： TiNiHf Nanocrystalline alloy Amorphous structure High-pressure torsion Hall-Petch relationship

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.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

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约翰的归来

约翰的归来

Analysis of local crystallographic orientation in an annealed Ti60 billet

作者： W.E.b.·杜波依斯(W.E.b. Du bois)

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Journal of Materials Science & Technology 2019年第4期35卷 591-595页

作者： Z.b.Zhao Z.Liu Q.J.Wang J.R.Liu R.Yang Institute of Metal Research Chinese Academy of Sciences School of Materials Science and Engineering University of Science and Technology of China

A heterogeneous microstructure in terms of local orientation distribution is often found in near-α titanium alloys. The presence of large regions with similar crystallographic orientation, called ‘macrozones',could drastically decrease the fatigue performance of titanium alloys. The present work reports on the crystallographic orientation of a near-α titanium alloy, Ti60, billet after annealing in an α+β phase *** texture was found to be weak, and no obvious macrozone was found in our measured zone where the variant selection is suppressed. Meanwhile, in-depth electron backscattered diffraction(EbSD) analysis was applied to evaluate the final microstructure, and the mechanisms by which they formed were analyzed.

关键词： Titanium alloys Microstructure Texture Heat treatment EbSD

Aerodynamic shape optimization of an urban maglev train

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Acta Mechanica Sinica 2021年第6期37卷 954-969,I0002页

作者： Z.X.Sun M.Y.Wang L.Y.Wei F.b.Kong G.W.Yang Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing100190China School of Engineering Science University of Chinese Academy of SciencesBeijing101408China CRRC Tangshan Co. Ltd TangshanHebei063000China

With rapid development of urban rail transit,maglev trains,benefiting from its comfortable,energy-saving and environmentally friendly merits,have gradually entered people's *** this paper,aiming at improving the aerodynamic performance of an urban maglev train,the aerodynamic optimization design has been *** improved two-point infill criterion has been adopted to construct the cross-validated Kriging ***,the multi-objective genetic algorithm and complex three-dimensional geometric parametrization method have been used,to optimize the streamlined head of the *** optimal shapes have been *** reveal that the optimization strategy used in this paper is sufficiently accurate and time-efficient for the optimization of the urban maglev train,and can be applied in practical *** to the prototype of the train,optimal shape benefits from higher lift of the leading car and smaller drag of the whole *** analysis reveals that the length and height of the streamlined head have a great influence on the aerodynamic performance of the train,and strong nonlinear relationships exist between these design variables and aerodynamic *** conclusions drawn in this study offer the chance to derive critical reference values for the optimization of the aerodynamic characteristics of urban maglev trains.

关键词： Urban maglev train Aerodynamic characteristics Cross validation Kriging model Genetic algorithm

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基于随机暴雨移置方法的城市设计暴雨分析

水科学进展 2020年第4期31卷 583-591页

作者：周正正刘曙光 Daniel b Wright 同济大学水利工程系上海200092 Department of Civil and Environmental Engineering University of WisconsinMadison WI 53706USA

城市地区暴雨洪灾发生频繁,合理计算设计暴雨是解决城市洪涝的重要前提。采用随机暴雨移置方法(Stochastic Storm Transposition,SST),设定暴雨移置区并提取出暴雨目录,通过区域性概率重采样与暴雨空间变换相结合的方式进行降雨频率分析... 详细信息

城市地区暴雨洪灾发生频繁,合理计算设计暴雨是解决城市洪涝的重要前提。采用随机暴雨移置方法(Stochastic Storm Transposition,SST),设定暴雨移置区并提取出暴雨目录,通过区域性概率重采样与暴雨空间变换相结合的方式进行降雨频率分析,估计本地化的极端暴雨频率。以上海地区为例,研究发现暴雨移置区内暴雨分布具有空间异质性,暴雨随机移置概率不均,计算得到的设计暴雨方案包含了降雨时空分布信息,在不同重现期下设计暴雨的时空结构存在变异性,说明传统方法中采用的简化雨型和均一化空间分布假设会增加设计暴雨的不确定性。

关键词：设计暴雨随机暴雨移置法城市流域上海市

The Ⅳ International Symposium ProGEO on the Conservation of the Geological Heritage

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Episodes 2006年第1期29卷 51-52页

作者： W. A. P. Wimbledom J. b. brilah Countryside Council for Wales/Cyngor Cefn Gwlad Cymru Castleton Court Fortran Road St Mellons Cardiff CFI OLT UK Earth Sciences Department University of Minho Campus de Gualtar 4710-057 braga PORTUGAL

The Ⅳ International Symposium ProGEO on the Conservation of the Geological Heritage was held between 13-16 September 2005 at braga organised by ProGEO （European Association for the Conservation of the Geological Heritage） and by the Earth Sciences Department of the University of Minho. The braga symposium builds on the earlier International Symposia, at Digne （1991）, Roma （1996）, and Madrid （1999）, and at ProGEO conferences hosted in countries and regions, too numerous to list--as well as workshops at the beijing and Firenze International Geological Congresses. These meetings have set the agenda for geoheritage （geosite, geo（morph）ological site） protection in the last ten years and introduced the ideas of comparative geosite inventories for countries and regions, of National Geoparks （with nested, protected geosite groups）, promoted the integration of geoconservation in strong national nature conservation, as well as links to landscape （Dublin 2002 conference） and geoarchaeological conservation.

关键词：地质资源国际座谈会学术讨论地质工作

Surface hardness,thermal,optical,and photon attenuation coefficients assessment for dysprosium-doped tellurite glasses

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Journal of Rare Earths 2023年第7期41卷 1083-1090,I0004页

作者： Hesham M.H.Zakaly D.E.Abulyazied H.A.Saudi b.M.Alotaibi Shams A.M.Issa Institute of Physics and Technology Ural Federal UniversityYekaterinburg620002Russia Faculty of Science Al-Azhar UniversityAssuit BranchAssuit71524Egypt Polymer Lab Department of PetrochemicalsEgyptian Petroleum Research InstituteNasr CityCairoEgypt Department of Physics Faculty of ScienceUniversity of TabukTabukSaudi Arabia Physics Department Faculty of ScienceAl-Azhar University(Girls Branch)Nasr CityCairoEgypt Department of Physics College of SciencePrincess Nourah Bint Abdulrahman UniversityP.O.Box 84428Riyadh11671Saudi Arabia

Using a melt-cooling process with the host glass,Dy_(2)O_(3)(1 wt%,2 wt%,3 wt%,and 4 wt%) doped tellurite glasses were produced.A(65-x)TeO_(2)-20b_(2)O_(3)-10Al_(2)O_(3)-SGeO_(2)-xDy_(2)O_(3) glass system was analyzed by Xray *** patterns have a hump at 2θ=27°-29° and no sharp peaks,indicating that all the glass samples are *** Vickers microhardness determines how resistant a glass is to persistent deformation produced by a harder *** scanning calorimetry(DSC) at 300-550℃ was used to evaluate the thermal properties of the Dy_x glass *** glass transition temperature T_g(small endothermic peak),start crystallization temperature T_x and crystallization temperature T_c can all be seen on the DSC thermogram(exothermic peaks).The UV-Vis transmittance and absorption spectra were *** optical data show that the values of E_d^(ir),E_g^(Ind) and E_U decrease as the amount of Dy_(2)O_(3)increases,indicating a narrowing of the tails due to localized states in the forbidden gap.A concentration quenching event occurs when Dy^(3+) concentrations are above a certain threshold(1%).The addition of Dy_(2)O_(3) increases glass density,while the addition of other Dy(Ⅲ) oxides increases sample *** radiation shielding values change as a consequence of density *** sample with the highest amount of Dy_(2)O_(3)(Dy_(4)) has stronger radiation shielding characteristics;hence,it is superior in terms of shielding outcomes at all energy *** Dy_x samples can be used in various forms of ionizing radiation shielding.

关键词： Melt-cooling process DSC Dysprosium(Ⅲ)oxides Surface hardness Photon attenuation Rare earths

Topological transverse thermoelectrics:A new way forward?

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The Innovation 2023年第6期4卷 23-24页

作者： Shubham Yadav b.M.Anil Kumar Satya N.Guin Department of Chemistry Birla Institute of Technology and SciencePilani-Hyderabad CampusHyderabad 500078India

Electronic structure is one of the most fundamental factors that decide the physical properties of a *** the past 18 years,a deeper fundamental understanding of the electronic band structure of material has resulted in the development of topological band theory,which has reclassified solid-state materials into two different classes:topologically trivial and topologically *** nontrivial systems provide a new opportunity for material design for fundamental and functional applications from experimental and theoretical viewpoints.

关键词： material. topological nontrivial