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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

Rapid solidification and metastable phase formation during surface modifications of composite Al-Cr cathodes exposed to cathodic arc plasma

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Journal of Materials Science & Technology 2021年第35期94卷 147-163页

作者： Mehran Golizadeh Francisca Mendez Martin Stefan Wurster Johann p.Mogeritsch Abdellah Kharicha Szilard Kolozsvári Christian Mitterer Robert Franz Department of Materials Science Montanuniversitat LeobenFranz Josef-Straβe 188700 LeobenAustria Erich Schmid Institute of Materials Science Austrian Academy of SciencesJahnstraβe 12.8700 LeobenAustria Department of Metallurgy Montanuniversitat LeobenFranz Josef-Straβe 188700 LeobenAustria plansee Composite Materials GmbH Siebenbiirgerstraβe 2386983 Lechbruck am SeeCermany

A combination of both conventional and advanced high-resolution characterization techniques was applied to study the modified layers on the surface of three composite Al-Cr arc cathodes with identical nominal composition of Al-50 at.%Cr but varying powder grain *** results revealed that the modified layers consist mainly of metastable phases such as Cr solid solution,high temperature cubic Al8 Cr5,supersaturated Al solid solution,and icosahedral *** metastable phase formation indicates that high cooling rates were involved during the solidification of molten material produced in the arc craters during cathode spot *** average cooling rate was estimated to be 10^(6)K/s based on secondary dendrite arm spacing measurements and supporting phase-field based *** formation mechanisms of the modified layers are discussed based on the obtained results and the current literature.

关键词： Cathodic arc Rapid solidification Quasicrystal Arc crater Macroparticle phase-field simulation

Some Aspects of the Diurnal and Semidiurnal Tidal Wind Field in Meteor Zone

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Advances in Atmospheric Sciences 1989年第3期6卷 357-364页

作者： p.C.S.Devara G.Chandrasekhar M.I.Ahmed Indian Institute of Tropical Meteorology Pune 411005IndiaDepartment of PhysicsAndhra UniversityWaltair 530003.IndiaDepartment of PhysicsAndhra UniversityWaltair 530003.India

The diurnal and semidiurnal tidal wind field variations in the altitudes between 80 and 100 km of the earth's atmosphere over a mid-latitude station are studied by means of the phases of the zonal and meridional wind measurements made at Atlanta (34 ° N, 84 ° W). The rotation of diurnal tidal wind vector is seen to be clockwise at lower heights (80-86 km), swinging between clockwise and anti-clockwise at intermediate heights (88-96 km) and anti-clockwise at higher heights (96-100 km). The senses of rotation of diurnal and semidiurnal tidal wind vectors are compared between the stations located in the same and opposite hemispheres. The results are consistent with the tidal theory in the case of Atlanta and Adelaide (35°S, 139 ° E) whereas in the case of other stations considered in the present study, they showed marked variations.

关键词： ph Some Aspects of the Diurnal and Semidiurnal Tidal Wind Field in Meteor Zone Wind

Geometrical Scale-Sensitive Fatigue properties of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si Alloys With α/β Lamellar Microstructures

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Journal of Materials Science & Technology 2014年第12期30卷 1284-1288页

作者： B.Zhang Z.M.Song L.M.Lei L.Kang G.p.Zhang Key Laboratory for Anisotropy and Texture of Materials Ministry of Education Northeastern University Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences AVIC Commercial Aircraft Engine Co. Ltd.

Fatigue properties of the Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy sheets containing different numbers of α/β Widmansttten colonies in the thickness direction of the sheets were investigated by tensionetension fatigue testing. It is found that fatigue properties of the Ti alloy either in low- or high-stress amplitude regimes become more sensitive to the sheet thickness of the Ti alloy as the sheet thickness is comparable to the length scale of the Widmansttten colonies. The basic mechanism of such length scale-sensitive fatigue properties in the Ti alloy was elucidated.

关键词： Fatigue Ti alloy Microstructure Size effect

Characterization,spectroscopic investigation of defects by positron annihilation,and possible application of synthesized pbO nanoparticles

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Chinese physics B 2021年第2期30卷 400-407页

作者： Sk Irsad Ali Anjan Das Apoorva Agrawal Shubharaj Mukherjee Maudud Ahmed p M G Nambissan Samiran Mandal Atis Chandra Mandal Department of physics University of BurdwanGolapbagBurdwan 713104West BengalIndia Department of physics A.P.C.Roy Government CollegeSiliguriDarjeeling 734010West BengalIndia Applied Nuclear physics Division Saha Institute of Nuclear Physics1/AF BidhannagarKolkata 700064India Department of physics Government General Degree College at PedongKalimpong 734311West BengalIndia

Nanocrystalline samples of highly pure lead oxide were prepared by the sol-gel route of synthesis.X-ray diffraction and transmission electron microscopic techniques confirmed the nanocrystallinity of the samples,and the average sizes of the crystallites were found within 20 nm to 35 *** nanocrystallites exhibited specific anomalous properties,among which a prominent one is the increased lattice parameters and unit cell *** optical band gaps also increased when the nanocrystallites became smaller in *** latter aspect is attributable to the onset of quantum confinement effects,as seen in a few other metal oxide *** annihilation was employed to study the vacancy type defects,which were abundant in the samples and played crucial roles in modulating their *** defect concentrations were significantly larger in the samples of smaller crystallite *** results suggested the feasibility of tailoring the properties of lead oxide nanocrystallites for technological applications,such as using lead oxide nanoparticles in batteries for better performance in discharge rate and *** also provided the physical insight into the structural build-up process when crystallites were formed with a finite number of atoms,whose distributions were governed by the site stabilization energy.

关键词： lead oxide nanocrystals positron annihilation sol-gel processes

Bionic Design and Finite Element Analysis of Elbow in Ice Transportation Cooling System

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Journal of Bionic Engineering 2010年第3期7卷 301-306页

作者： Dejun Miao~(1,2), Xiuhua Sui~3, Linjing Xiao~3 1. Key Laboratory of Mine Hazard prevention and Control (Ministry of Education, China), Shandong University of Science and Technology, Qingdao 266510, p. R. China 2. School of Architecture, Tsinghua University, Beijing 100084, p. R. China 3. College of Mechanical and Electronic Engineering, Shandong University of Science and Technology, Qingdao 266510, p. R. China Key Laboratory of Mine Hazard prevention and Control (Ministry of Education China) Shandong University of Science and Technology Qingdao P. R. China School of Architecture Tsinghua University Beijing P. R. China College of Mechanical and Electronic Engineering Shandong University of Science and Technology Qingdao P. R. China

With the increase in mining depth, mine heat harm has appeared to be more prominent. The mine heat harm could be resolvedor reduced by ice refrigeration. Thus, ice transportation through pipeline becomes a critical problem; typically flowresistance occurs in the elbow. In the present study, according to the analysis of the surface morphology of fish scale, abiomimetic functional surface structure for the interior wall of elbow is designed. Based on the theory of liquid-solid two phaseflow, a CFD numerical simulation of ice-water mixture flowing through the elbow is carried out using finite element *** experiments of pressure drop and flow resistance for both bionic and common elbows are conducted to test theeffect of the bionic elbow on flow resistance reduction. It is found that with the increase in the ice mass fraction in the ice-watermixture, the effect of bionic elbow on resistance reduction becomes more obvious.

关键词： bionic elbow two phase flow ice transportation flow resistance reduction pressure loss

Synthesis and photoluminescent performance of novel europium(Ⅲ) carboxylates with heterocyclic ancillary ligands

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Rare Metals 2022年第4期41卷 1342-1352页

作者： priyanka Dhankhar Rekha Devi Sushma Devi Sangeeta Chahar Mandeep Dalal V.B.Taxak S.p.Khatkar priti Boora Department of Chemistry Maharshi Dayanand UniversityRohtak 124001India

Five novel europium(Ⅲ)complexes with 2-[4-(dibutylamino)-2-hydroxybenzoyl]benzoic acid(DAHB)as primary ligand and bathophenanthroline(batho),2,2’-bipyridyl(bipy),5,6-dimethyl-1,10-phenanthroline(dmph),1,10-phenanthroline(phen)as ancillary ligands were syn-thesized via solution precipitation *** structural formulae of synthesized complexes were speculated to be Eu(DABH)_(3)·2H_(2)O(C1),Eu(DABH)_(3)·batho(C2),Eu(DABH)_(3)·bipy(C3),Eu(DABH)_(3)·dmph(C4)and Eu(DABH)_(3)·phen(C5)by elemental analysis,infrared spectroscopy and proton nuclear magnetic resonance spec-troscopy(^(1)H-NMR).The photoluminescent properties and thermal stability of the complexes were investigated by photoluminescent spectroscopy and thermogravimetric analysis(TG-DTG),*** Commission Inter-nationale de I’Eclairage(CIE)color coordinates,Judd–Ofelt intensity parameter(Ω_(2)),total quantum yield,intrinsic quantum efficiency and energy transfer dynamics of com-plexes were also *** excitation spectra of com-plexes are extended up to visible *** complexes exhibit characteristic photoemission of Eu^(3+)metal ion with high color purity in red region attributed to efficient energy transfer from ligand to metal *** replacement of water molecules from coordination sphere of europium ion by ancillary ligands results in enhancement of luminescent properties of the C2–C5 complexes,indicating that ancillary ligands act as additional light harvesting centers in sensiti-zation *** thermal studies show that these complexes are suitable for meeting the requirement of temperature for fabrication of OLEDs devices.

关键词： photoluminescence Europium Sensitization Aromatic carboxylic acid Energy transfer dynamics

Degradation and fate of 2,4-dinitroanisole(DNAN)and its intermediates treated with Mg/Cu bimetal:Surface examination with XAS,DFT,and LDI-MS

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Journal of Environmental Sciences 2023年第7期129卷 161-173页

作者： Andrew Mai Emese Hadnagy Qiantao Shi Lotanna Ezeonu Jason p.Robbins Simon G.podkolzin Agamemnon Koutsospyros Christos Christodoulatos Center for Environmental Systems Stevens Institute of TechnologyHobokenNJ 07030USA School of Engineering and Technology University of Washington TacomaTacomaWA 98402USA

A novel Mg-based bimetal reagent(Mg/Cu)was used as an enhanced reductive system to degrade insensitivemunition 2,4-dinitroanisole(DNAN),a contaminant found in *** ofDNANwas significantly impacted by dissolved oxygen and studied in anoxic and oxic bimetal systems(i.e.,purging with N2,air,or O_(2) gas).Degradation occurred through sequential nitroreduction:first one nitro group was reduced(ortho or para)to form short-lived intermediates 2-amino-4-nitroanisole or 4-amino-2-nitroanisole(2-ANAN or 4-ANAN),and then subsequent reduction of the other nitro group formed 2,4-diaminoanisole(DAAN).The nitro-amino intermediates demonstrated regioselective reduction in the ortho position to 2-ANAN;Regioselectivity was also impacted by the anoxic/oxic *** O_(2)-purging DNAN degradation rate was slightly enhanced,but most notably O_(2) significantly accelerated DAAN *** also further degraded only in the oxygenated Mg/Cu *** of DNAN byproducts to the reagent occurred regardless of anoxic/oxic condition,resulting in a partition of carbon mass between the adsorbed phase(27%-35%)and dissolved phase(59%-72%).Additional surface techniqueswere applied to investigate contaminant interaction with *** functional theory(DFT)calculations identified preferential adsorption structures for DNAN on Cu with binding through two O atoms of one or both nitro groups.X-ray absorption spectroscopy(XAS)measurements determined the oxidation state of catalyticmetal Cu and formation of a Cu-O-N bond during *** desorption ionization mass spectrometry(LDI-MS)measurements also identified intermediate 2-ANAN adsorbed to the bimetal surface.

关键词： Insensitive munition Magnesium bimetal Reductive degradation Adsorption Surface analysis DFT DNAN Oxic

High Resolution Synchrotron Diffraction Study on Charge Density Distribution of Ampicillin Trihydrate

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Chinese Journal of Chemical physics 2017年第1期30卷 50-62,I0001页

作者： C. Anzline S. lsrael R. Niranjana Devi R. A. J, R.Sheeba p. Richard Rajkumar Research and postgraduate Department of physics The American college Madurai 625002 Tamil Nadu India Mother Teresa Women＇s University Kodaikanal 624102 Tamil Nadu India Research and postgraduate Department of physics Madura College Madurai 625001 Tamil IVadu India

Charge density distribution in ampicillin trihydrate was investigated experimentally. Results were compared with the quantum calculations using density functional theory. The charge derived properties including Mulliken atomic charges, dipole moment, and molecular electrostatic potential were calculated. The multipole analysis was done for the refinement of experimental population parameters. The structure factors obtained from multipole treat- ment were used for the construction of Fourier maps. Topological properties of the charge distribution were discussed and the characteristics of （3, -1） critical points were analyzed.

关键词： Charge density Multipole analysis Density functional theory Electrophilicity index