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delayed plasticity during spherical nanoindentation of.an iron-chromium-aluminum alloy:Ef.ect of.f.rric ion irradiation

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Journal of.Materials Science & Technology 2023年第36期167卷 228-236页

作者： y.Zhang c.W.Li J.L.Jiang J.f.Gu H.Wang y.d.Jia G.Wang X.G.An Q.Wang J.Lu Institute of.Materials Shanghai UniversityShanghai 200072China School of.Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China department of.Mechanical Engineering City University of Hong KongKowloonSARChina Science and Technology on Reactor f.el and Materials Laboratory Nuclear Power Institute of ChinaChengdu 610041China Interdisciplinary Materials Research center Institute for Advanced StudyChengdu UniversityChengdu610106China

Spherical nanoindentation of.an iron-chromium-aluminum alloy was conducted to study the ef.ect of.f.rric-ion(f. 3+)irradiation on the time-dependent plasticity behavior in the surf.ce layers of.this *** was observed that the initiation of.plasticity by the appearance of.displacement burst or“pop-in”event occurred af.er a period of.waiting time in the apparent elastic regime and that f.^(3+)irradiation at 360°c and up to∼0.5 displacements per atom could make it happen under the lower applied loads but with a reduced *** the experimental data,an activation volume and activation energy were extracted f.r the delayed *** results show that f.^(3+)-irradiation signif.cantly reduced its acti-vation volume f.om∼3.05 b 3 to∼1.75 b 3(where b=Burgers vector),but slightly increased its activation energy f.om∼0.65 to∼0.71 *** the other hand,high-resolution scanning transmission electron mi-croscopy observations reveal that the irradiation at the elevated temperature created interstitial atom pair onto the(100)habit plane that can serve as the nucleation site of.a100dislocation loop while elim-inating the pre-existing ***,it is indicated that heterogeneous nucleation of.the dislocation loop was predominant in the delayed plasticity initiation of.this alloy and that the nucleation of.the interstitial-type dislocation loop was involved due to f.^(3+)-irradiation.

关键词： Spherical nanoindentation delayed plasticity f.crAl alloy f.^(3+)-irradiation

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STRUcTURE, MEcHANIcAL PROPERTIES ANd THERMAL STABILITy Of.dIAMONd-LIKE cARBON f.LMS PREPAREd By ARc ION PLATING

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 331-338页

作者： y.S.Zou J.d.Zheng J.Gong c.Sun R.f.Huang L.S.Wen divisionof.urf.ceEngineeringof.aterials InstituteofMetalResearchTheChineseAcademyofSciencesShenyang110016China divisionof.urf.ceEngineeringof.aterials InstituteofMetalResearchTheChineseAcademyofSciencesShenyang110016China／／ShenyangResearchCenterforInterfacialMaterialsShenyang110016China

diamond-like carbon (dLc) f.lms have been prepared on Si(100) substrates by arc ion plating in conjunction with pulse bias voltage under H2 atmosphere. The depo sited f.lms have been characterized by scanning electron microscopy and atomic f.orce microscopy. The results show that the surf.ce of.the f.lm is smooth and den se without any cracks, and the surf.ce roughness is low. The bonding characteris tic of.the f.lms has been studied by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. It shows the sp3 bond content of.the f.lm deposited at -200V is 26.7%. The hardness and elastic modulus of.the f.lm determined by nanoindent ation technique are 30.8 and 250.1GPa, respectively. The tribological characteri stic of.the f.lms reveals that they have low f.iction coef.icient and good wear- resistance. Af.er deposition, the f.lms have been annealed in the range of.350-7 00℃ f.r 1h in vacuum to investigate the thermal stability. Raman spectra indica te that the Id/IG ratio and G peak position have f.w detectable changes below 50 0℃. f.rther increasing the annealing temperature, the hydrogen can be released, the structure rearranges, and the phase transition of.sp3 conf.gured carbon to sp2 conf.gured carbon appears.

关键词： diamond-like carbon arc ion plating microstructure mechanical

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Evaluation of.stress intensity f.ctors f.r bi-material interf.ce cracks using displacement jump methods

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Acta Mechanica Sinica 2017年第6期33卷 1051-1064页

作者： K. c. Nehar B. E. Hachi f. cazes M. Haboussi Laboratoire de développement en mécanique et matériaux (LdMM) Université de Djelfa PB 3117 Djelfa Algeria Laboratoire des Sciences des Procédés et des Matériaux (LSPM) UPR 3407 CNRS Université Paris 13 Paris France

The aim of.the present work is to investigate the numerical modeling of.interf.cial cracks that may appear at the interf.ce between two isotropic elastic materials. The extended f.nite element method is employed to analyze brittle and bi-material interf.cial f.tigue crack growth by computing the mixed mode stress intensity f.ctors(SIf.. Three dif.erent approaches are introduced to compute the SIf.. In the f.rst one, mixed mode SIf.is deduced f.om the computation of.the contour integral as per the classical J-integral method,whereas a displacement method is used to evaluate the SIf.by using either one or two displacement jumps located along the crack path in the second and third approaches. The displacement jump method is rather classical f.r mono-materials,but has to our knowledge not been used up to now f.r a bimaterial. Hence, use of.displacement jump f.r characterizing bi-material cracks constitutes the main contribution of.the present study. Several benchmark tests including parametric studies are perf.rmed to show the ef.ectiveness of.these computational methodologies f.r SIf.considering static and f.tigue problems of.bi-material structures. It is f.und that results based on the displacement jump methods are in a very good agreement with those of.exact solutions, such as f.r the J-integral method, but with a larger domain of.applicability and a better numerical ef.iciency(less time consuming and less spurious boundary ef.ect).

关键词： Bi-material interf.ce crack Mixed mode stress intensity f.ctor displacement jump X-f.M f.tigue crack growth

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Ef.ects of.Sic Nanoparticle content on the Microstructure and Tensile Mechanical Properties of.Ultraf.ne Grained AA6063-Sic_(np) Nanocomposites f.bricated by Powder Metallurgy

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Journal of.Materials Science & Technology 2017年第9期33卷 1023-1030页

作者： X.yao Z.Zhang y.f.Zheng c.Kong M.Z.Quadir J.M.Liang y.H.chen P.Munroe d.L.Zhang State Key Laboratory of.Metal Matrix composites School of Materials Science and EngineeringShanghai Jiao Tong University Electron Microscope Unit University of New South Wales School of.Materials Science and Engineering University of New South Wales

Ultraf.ne grained AA6063-Sicnpnanocomposites with 1, 5 and 10 vol.% Sicnphave been f.bricated by a novel powder metallurgy process. This process combines high energy ball milling of.a mixture of.6063 alloy granules made f.om machining chips and Si c nanoparticles and thermomechanical powder consolidation by spark plasma sintering and hot extrusion. The microstructure and tensile mechanical properties of.the samples were investigated in detail. Increasing the Si c nanoparticle content f.om 1 to 10 vol.%,the yield strength and ultimate tensile strength increased f.om 296 and 343 MPa to 545 and 603 MPa respectively, and the elongation to f.acture decreased f.om 10.0%, to 2.3%. As expected, a higher Si c nanoparticle content generates a stronger inhibiting ef.ect to grain growth during the thermomechanical powder consolidation process. Analysis of.the contributions of.various strengthening mechanisms shows that a higher Si c nanoparticle content leads to a higher contribution f.om nanoparticle strengthening, but grain boundary strengthening still makes the largest contribution to the strength of.the *** the Si c nanoparticle content increased to 10 vol.%, the f.ilure of.the nanocomposite was initiated at weakly-bonded interparticle boundaries(IPBs), indicating that with a high f.ow stress during tensile def.rmation, the f.ilure of.the material is more sensitive to the presence of.weakly-bonded IPBs.

关键词： Metal matrix nanocomposite Ultraf.ne grained material Powder metallurgy Tensile mechanical properties

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High strength-superplasticity combination of.ultraf.ne-grained f.rritic steel:The signif.cant role of.nanoscale carbides

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Journal of.Materials Science & Technology 2021年第24期83卷 131-144页

作者： J.W.Liang y.f.Shen R.d.K.Misra P.K.Liaw Key Laboratory f.r Anisotropy and Texture of.Materials(MOE) School of Materials Science and EngineeringNortheastern UniversityShenyang110004China The State Key Lab of.Rolling&Automation Northeastern UniversityShenyang110819China Laboratory f.r Excellence in Advanced Steel Research University of Texas at El PasoTX79968USA department of.Materials Science and Engineering University of TennesseeKnoxvilleTN37996USA

There is currently a gap in our understanding of.mechanisms that contribute to high strength and high plasticity in high strength Uf. f.rritic steel with nano-size f.3 c carbides in situations that involve combination of.various strain rates and high *** this regard,we describe the mechanistic basis of.obtaining high strength-high plasticity combination in an ultraf.ne-grained(Uf.)(~500±30 nm)f.rritic steel with nano-size carbides,which sustained large plastic def.rmation,exceeding 100%elongation at a temperature signif.cantly below 0.5 of.the absolute melting point(Tm).To address the missing gap in our knowledge,we conducted a series of.experiments involving combination of.strain rate and temperature ef.ects in conjunction with electron microscopy and atom probe tomography(APT).Strain rate studies were carried out at strain rates in the range of.0.0017-0.17 s^(-1)and at dif.erent temperatures f.om 25℃to 600℃.dynamic recrystallization occurred at 600℃,resulting in a signif.cant decrease in yield and tensile ***,the Uf. f.rritic steels had an advantage in tensile strength(UTS)and elongation-to-f.ilure(εf.at 600℃,especially at strain rate of.0.0017 s^(-1),with high UTSof.510 MPa and excellent low temperature(city(εf.110%).These mechanical properties are signif.cantly superior compared to similar type of.steels at identical temperature.A mechanistic understanding of.mechanical behavior of.Uf. f.rritic steels is presented by combining the ef.ect of.strain rate,temperature,and nano-size carbides.

关键词： Uf. f.rritic steel Strain rate Temperature Nano-size precipitate Low temperature superplasticity

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Zinc Redistribution in a Soil developed f.om Limestone during Pedogenesis

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Pedosphere 2009年第3期19卷 292-304页

作者： c. LAVEUf.S. cORNU d. BAIZE M. HARdy O. JOSIERE S. dROUIN A. BRUANd f. JUILLOT INRA UR0272 Science du Sol Centre de recherche d'Orlans 45075 Orlans cedex 2 (France) ISTO UMR 6113 CNRS Universit d'Orlans 45071 Orlans cedex 2 (France) ISTO UMR 6113 CNRS Universitd'Orlans 45071 Orlans cedex 2 (France) IMPMc UMR CNRS 7590 Universit Paris 6 et 7 IPGC 75252 Paris cedex 05 (France)

The long-term redistribution of.Zn in a naturally Zn-enriched soil during pedogenesis was quantif.ed based on mass balance calculations. According to their f.te, parent limestones comprised three Zn pools: bound to calcite and pyritesphalerite grains, bound to phyllosilicates and bound to goethite in the inherited phosphate nodules. f.ur pedological processes, i.e., carbonate dissolution, two stages of.redox processes and eluviation, redistributed Zn during pedogenesis. The carbonate dissolution of.limestones released Zn bound to calcite into soil solution. due to residual enrichment, Zn concentrations in the soil are higher than those in parent limestones. Birnessite, f.rrihydrite and goethite dispersed in soil horizon trapped high quantities of.Zn during their f.rmation. Af.erwards, primary redox conditions induced the release of.Zn and f. into soil solution, and the subsequent individualization of.f. and Mn into Zn-rich concretions. Both processes and subsequent aging of.the concretions f.rmed induced signif.cant exportation of.Zn through the bottom water table. Secondary redox conditions promoted the weathering of.f. and Mn oxides in cements and concretions. This process caused other losses of.Zn through lateral exportation in an upper water table. concomitantly, eluviation occurred at the top of.the solum. The lateral exportation of.eluviated minerals through the upper water table limited illuviation. Eluviation was also responsible f.r Zn loss, but this Zn bound to phyllosilicates was not bioavailable.

关键词： carbonate dissolution eluviation long-term redox speciation

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Multi-channel retarding f.eld analyzer f.r EAST

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Plasma Science and Technology 2018年第5期20卷 1-5页

作者： M HENKEL d HOScHEN y LIANG y LI S c LIU d NIcOLAI N SANdRI G SATHEESWARAN N yAN H X ZHANG the EAST team f.rschungszentrum Jülich GmbH Institut für Energie-und Klimaforschung–PlasmaphysikPartner of the Trilateral Euregio Cluster(TEC)D-52425 JulichGermany Institute of.Plasma Physics Chinese Academy of SciencesHefei 230031People's Republic of China

A multi-channel retarding f.eld analyzer（Mc-Rf.） including two Rf. modules and two Langmuir probes to measure the ion and electron temperature prof.les within the scrape-of. layer was developed f.r investigations of.the interplay between magnetic topology and plasma transport at the plasma *** Mc-Rf. probe f.r the stellarator W7-X and f.rst measurements at the tokamak EAST was *** probe head allows simultaneous multichannel ion temperature as well as f.r electron temperature *** usability f.r radial correlation measurements of.the measured ion currents is also given.

关键词： retarding f.eld analyzer multi-channel EAST ion temperature diagnostic

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Uncovering the sof.ening mechanism and exploring the strengthening strategies in extremely f.ne nanograined metals:A molecular dynamics study

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Journal of.Materials Science & Technology 2022年第14期109卷 186-196页

作者： H.R.Peng Z.y.Jian c.X.Liu L.K.Huang y.M.Ren f.Liu School of.Materials and chemical Engineering Xi’an Technological UniversityXi’an 710021China State Key Laboratory of.Solidif.cation Processing Northwestern Polytechnical UniversityXi’an 710072China

The strength of.polycrystalline metals increases with decreasing grain size,f.llowing the classical HallPetch ***,this relationship f.ils when sof.ening occurs at very small grain sizes(typically less than 10 to 20 nm),which limits the development of.ultrahigh-strength *** this work,using columnar-grained nanocrystalline cu-Ag‘samples’,molecular dynamics simulations were perf.rmed to investigate the sof.ening mechanism and explore the strengthening strategies(e.g.,f.rmation of.solid solution or grain boundary(GB)segregation)in extremely f.ne nanograined ***,the sof.ening of.pure metals is induced by atomic sliding in the GB layer,rather than dislocation activities in the grain interior,although both occur during *** solid solution lowers the stacking f.ult energy and increases the GB energy,which leads to the sof.ening of.Nc *** segregation stabilizes GB structures,which causes a notable improvement in strength,and this improvement can be f.rther enhanced by optimizing the solute concentration and GB *** work deepens the understanding of.the sof.ening mechanism due to atomic sliding in the GB layer and the strengthening mechanism arising f.om tailoring the GB stability of.immiscible alloys and provides insights into the design of.ultrahighstrength materials.

关键词： Sof.ening Strengthening cu-Ag alloy Molecular dynamics Nanocrystalline

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Synthesis and characterization of.caAl_xO_y:Eu^(2+) phosphors prepared using solution-combustion method

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Journal of.Rare Earths 2010年第S1期28卷 272-276页

作者： f.B.dejene d.B.Bem H.c.Swart department of.Physics University of the Free State(Qwaqwa Campus)Private Bag X13Phuthaditjhaba9866South Africa department of.Physics University of the Free StateP.O.Box 339Bloemfontein9300South Africa

Europium-doped calcium aluminate(caAlxOy:Eu2+) phosphors were obtained at low temperatures(500 oc) by the solution-combustion of.corresponding metal nitrate-urea solution *** particle size and morphology and the structural and luminescent properties of.the as-synthesized phosphors were examined by means of.scanning electron microscopy(SEM),X-ray dif.raction(XRd),Auger spectroscopy,transmission electron spectroscopy(TEM) and photoluminescence(PL).It was f.und that the ca:Al molar ratios showed greatly inf.uence not only on the particle size and morphology,but also on their PL spectra and *** the ca:Al molar ratios increasing f.om 6:100 to 26:100,the structure of.as-synthesized phosphor changed f.om caAl12O19 to monoclinic caAl2O4 and the dominant emitting light f.om red to blue,implying that the oxidation state of.doped europium ions changed f.om trivalent to divalent due to the structure variation of.host lattice.A blue phosphor with almost pure phase can be easily prepared by solution combustion method with suitable ca:Al molar ratio.

关键词： caAlxOy:Eu2+ solution-combustion molar ratio structure luminescence rare earths

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Ef.ectiveness of.air cleaner on mitigating the transmission of.respiratory disease in a dental clinic environment

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Building Simulation 2024年第10期17卷 1789-1803页

作者： Gang yang yif.n Wang Ka chung chan Kwok Wai Mui thomas f.f.emmig Sthomas Ng christopher y.H.chao Sau chung f. department of.Building Environment and Energy Engineering The Hong Kong Polytechnic UniversityHong KongChina f.culty of.dentistry The University of Hong KongHong KongChina department of.Architecture&civil Engineering City University of Hong KongHong KongChina department of.Mechanical Engineering The Hong Kong Polytechnic UniversityHong KongChina

In dental clinics with an open f.oor plan,the risk of.patient-to-patient transmission of.respiratory disease is a *** dental procedures large amounts of.bioaerosol are produced and patients cannot wear personal protective *** paper examines how to ef.ectively deploy air cleaner to reduce the inf.ction risk in dental clinics with an open f.oor *** locations of.air cleaners at various clean air delivery rates(cAdRs)were *** dispersion of.bioaerosol was studied through numerical simulations,and risk assessment was perf.rmed by a dose-response *** f.ndings indicated that dental patients downstream of.the background ventilation have a higher inf.ction risk than those to the lef. and right of.an inf.cted patient(i.e.,the source).The lowest inf.ction risks f.r the adjacent patients were f.und when the air cleaner was place opposite to the dentists,i.e.,on the f.oor at low cAdR levels of.2.2 m^(3)/min or on the bench at cAdR levels of.4.4 m^(3)/min or *** results of.this study indicated that air cleaner can mitigate the risk of.patient-to-patient transmission of.SARS-coV-2 in dental clinics with an open f.oor *** cAdR levels determine the optimal placement of.air cleaners.

关键词： inf.ction risk air cleaner location dental clinic cf. simulation respiratory disease

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