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Hardening and toughening effects of intermediate nanosized structures in a confined amorphous alloy film

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journal of Materials Science & Technology 2022年第23期118卷 44-53页

作者： z.Q.Chen M.C.li X.Tong y.zhao j.y.Xie S.W.Guo P.huang F.Wang H.b.Ke b.A.Sun W.H.Wang Songshan Lake Materials Laboratory Dongguan 523808China Institute of Physics Chinese Academy of SciencesBeijing 100190China Xinjiang Key Laboratory of Solid State Physics and Devices and School of Physical Science and Technology Xinjiang UniversityXinjiangUrumqi 830046China Key Laboratory of LCR Materials and Devices of yunnan Province School of Materials and EnergyYunnan UniversityKunming 650091China State-Key Laboratory for Mechanical behavior of Material Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong UniversityXi’an 710049China National Demonstration Center for Experimental Mechanics Education Xi’an Jiaotong UniversityXi’an 710049China

The plastic deformation of amorphous alloys is well known to be localized into shear bands(Sbs),which are believed to stem from the atomic-scale flow defects,i.e.,shear transformation zones(STzs).yet,the bridge between the mesoscopic Sbs and the atomic-scale STzs remains poorly *** this work,through thermally activating pronouncedβrelaxations in the well-designed crystalline-layer confined amorphous(CLCA)Ni W alloy films,we experimentally captured and observed an intermediate nanosized structure termed as“nano shear bands”(NSbs)with a typical size of 1–2 nm in thickness and5–10 nm in *** influences of such NSb structures on the macroscale deformation behavior were systematically *** was found that NSbs lead to both hardening and toughening effects for the CLCA films,as they promote multiple and controlled shear banding deformation,which results in enhanced *** intermediate NSb structure could connect the microstructural characteristics and macroscopic plasticity in amorphous alloys and may provide new insights for understanding the microscopic deformation mechanism of amorphous alloys as well as tuning/designing their properties.

关键词： Amorphous alloys Nano shear band Hardening Toughening Crystallization

Single crystal growth, structural and transport properties of bad metal RhSb2

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Chinese Physics b 2020年第3期29卷 1-6页

作者： D S Wu y T Qian z.y.liu W Wu y j li S H Na y T Shao P zheng G li j G Cheng H M Weng j L Luo beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China

We have successfully grown an arsenopyrite marcasite type RhSb2 single crystal, and systematically investigated its crystal structure, electrical transport, magnetic susceptibility, heat capacity, and thermodynamic properties. We found that the temperature-dependent resistivity exhibits a bad metal behavior with a board peak around 200 K. The magnetic susceptibility of RhSb2 shows diamagnetism from 300 K to 2 K. The low-temperature specific heat shows a metallic behavior with a quite small electronic specific-heat coefficient. No phase transition is observed in both specific heat and magnetic susceptibility data. The Hall resistivity measurements show that the conduction carriers are dominated by electrons with ne = 8.62 × 10^(18) cm^(-3) at 2 K, and the electron carrier density increases rapidly above 200 K without change sign. Combining with ab-initio band structure calculations, we showed that the unusual peak around 200 K in resistivity is related to the distinct electronic structure of RhSb_2. In addition, a large thermopower S(T) about -140 μV/K is observed around 200 K, which might be useful for future thermoelectric applications.

关键词： single crystal growth ab-initio band calculations susceptibility heat capacity thermodynamic transport properties

Improving the hard magnetic properties by intragrain pinning for Ta doped nanocrystalline Ce-Fe-b alloys

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journal of Materials Science & Technology 2019年第9期35卷 1877-1885页

作者： j.S.zhang W. li X.F. liao H.y. yu L.z. zhao H.X. zeng D.R. Peng z.W. liu School of Materials Science and Engineering South China University of TechnologyGuangzhou510640China Innovative Center for Advanced Materials (ICAM) Hangzhou Dianzi UniversityHangzhou310012China

To develop Ce based permanent magnets with high performance/cost ratio, Ta doping is was employed to enhance the magnetic performance of Ce-Fe-b alloys. For melt spun Cei7Fe78-xTaxb6 (x = 0-1) alloys, the coercivity Hc increases from 439 to 553 kA/m with increasing x value from 0 to 0.75. Microstructure characterizations indicate that Ta doping is helpful for grain refinement. A second phase of Tab2 is observed in Ce17Fe77.25Tao.75b6 alloy, which acts as the pinning center of the magnetic domains, resulting in the change of coercivity mechanism from nucleation type to nucleation +pinning type. The micromagnetic simulation confirms that non-magnetic particles within hard magnetic phase can increase the demagnetization field around them and it is crucial for preventing the further magnetization reverse by pinning effect. Take the advantage of Ta doping for enhancing the coercivity, Ce content of Ce-Fe-b alloy can be further cut down to increase the remanence jr due to the reduced volume fraction of CeFe2 phase and increased Fe/Ce ratio. As a result, a good combination of magnetic properties with Hc = 514 kA/m, jr = 0.49 T, and the maximum energy product (bH)max = 36 kj/m^3 have been obtained in Ce15Fe79.25Tao.75b6 alloy. It is expected that the present work can serve as a useful reference for designing new permanent magnetic materials with low-cost.

关键词： Melt-spinning Permanent magnets Second phase Coercivity mechanism Thermal stability

Expected energy spectrum of cosmic ray protons and helium below4 PeV measured by LHAASO

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Chinese Physics C 2019年第7期43卷 86-96页

作者： L.Q.yin S.S.zhang z.Cao b.y.bi C.Wang j.L.liu L.L.Ma M.j.yang y.zhang z.y.you z.z.zong Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences University of Chinese Academy of Science Institut für Astronomie und Astrophysik Eberhard Karls Universit?t Kunming University Institut de Physique Nucléaire d’Orsay IN2P3-CNRS Université Paris-Sud China Nuclear Power Engineering Co. Ltd.

The Large High Altitude Air Shower Observatory(LHAASO) is a composite cosmic ray observatory consisting of three detector arrays: kilometer square array(KM2 A), which includes the electromagnetic detector array and muon detector array, water Cherenkov detector array(WCDA) and wide field-of-view Cherenkov telescope array(WFCTA). One of the main scientific objectives of LHAASO is to precisely measure the cosmic rays energy spectrum of individual components from 10^14 eV to 10^18 eV. The hybrid observation will be employed by the LHAASO experiment, in which the lateral and longitudinal distributions of extensive air shower can be observed simultaneously. Thus, many kinds of parameters can be used for primary nuclei identification. In this paper, high purity cosmic ray simulation samples of the light nuclei component are obtained using multi-variable analysis. The apertures of 1/4 LHAASO array for pure proton and mixed proton and helium(H&He) samples are 900 m^2 Sr and1800 m^2 Sr, respectively. Prospect of obtaining proton and H&He spectra from 100 TeV to 4 PeV is discussed.

关键词： LHAASO hybrid measurement energy spectrum composition TMVA

A practical model for efficient anti-fatigue design and selection of metallic materials:Ⅰ.Model building and fatigue strength prediction

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journal of Materials Science & Technology 2021年第11期70卷 233-249页

作者： R.liu P.zhang z.j.zhang b.Wang z.F.zhang Laboratory of Fatigue and Fracture for Materials Shi-changxu Innovation Center for Advanced MaterialsInstitute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China

The high cost and low efficiency of fatigue tests are bottleneck problem for the anti-fatigue design of metallic *** this problem,a theoretical fatigue model is proposed in this study,the possible applications have also been *** results would be introduced in two serial papers,in which the first paper focuses on the model building and the applications on fatigue strength prediction;the second paper put emphasis on the influencing factors of the model parameters and the applications on fatigue strength *** this first paper,a theoretical model is proposed considering both the strength and plastic restrictions of fatigue *** the model builds up a brief relationship among yield strength(y),tensile strength(T)and fatigue strength(F),it is named as the y-T-F *** the verification with fatigue strength data covering various kinds of metallic materials and loading conditions,this y-T-F model exhibits both generality and *** the y-T-F model,the efficient fatigue strength prediction could be conducted by brief linear fitting and calculation,just through yield strength,tensile strength and several known fatigue strength ***,through its deduced y-F model,the analytical formula of fatigue strength continuously changing with materials strengthening can be obtained,as well as the maximum value of fatigue strength and corresponding critical yield *** summary,the y-T-F model would be useful for reducing the fatigue tests,thus providing new possibilities on the efficient anti-fatigue design and selection of metallic materials.

关键词： yield strength Tensile strength Plasticity Fatigue strength Anti-fatigue design

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Optimization of N18 zirconium Alloy for Fuel Cladding of Water Reactors

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journal of Materials Science & Technology 2012年第7期28卷 606-613页

作者： b.X. zhou M. y. yao z.K. li X.M. Wang j. zhoua C.S. Long Q. liu b.F. Luan Laboratory for Mierostructures Shanghai University Shanghai 200444 China Institute of Materials Shanghai University Shaxighai 200072 China Northwest Institute for Non-ferrous Metal Research Xian 721014 China Key Laboratory for Nuclear Fuel and Materials Nuclear Power Institute of China Chengdu 610041 China College of Material Science and Engineering Chongqing University Chongqing 400044 China

In order to optimize the microstructure and composition of N18 zirconium alloy （zr-1Sn-0.35Nb-0.35Fe-0.1Cr, in mass fraction, %）, which was developed in China in 1990s, the effect of microstructure and composition variation on the corrosion resistance of the N18 alloy has been investigated. The autoclave corrosion tests were carried out in super heated steam at 400 ~C/10.3 MPa, in deionized water or lithiated water with 0.01 mol/L liOH at 360 ~C/18.6 MPa. The exposure time lasted for 300-550 days according to the test temperature. The results show that the microstructure with a fine and uniform distribution of second phase particles （SPPs）, and the decrease of Sn content from 1% （in mass fraction, the same as follows） to 0.8% are of benefit to improving the corrosion resistance; It is detrimental to the corrosion resistance if no Cr addition. The addition of Nb content with upper limit （0.35%） is beneficial to improving the corrosion resistance. The addition of Cu less than 0.1% shows no remarkable influence upon the corrosion resistance for N18 alloy. Comparing the corrosion resistance of the optimized N18 with other commercial zirconium alloys, such as zircaloy-4, zIRLO, E635 and Ell0, the former shows superior corrosion resistance in all autoclave testing conditions mentioned above. Although the data of the corrosion resistance as fuel cladding for high burn-up has not been obtained yet, it is believed that the optimized N18 alloy is promising for the candidate of fuel cladding materials as high burn-up fuel assemblies. based on the theory that the microstructural evolution of oxide layer during corrosion process will affect the corrosion resistance of zirconium alloys, the improvement of corrosion resistance of the N18 alloy by obtaining the microstructure with nano-size and uniform distribution of SPPs, and by decreasing the content of Sn and maintaining the content of Cr is discussed.

关键词： zirconium alloys Corrosion resistance Composition variation Microstructure

NUMERICAL STUDy OF TURbULENT IMPINGING jET WITH A REFINED k-ε MODEL

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journal of Hydrodynamics 2000年第4期12卷 8-15页

作者： Xu, j.L. Xu, z. huang, S.j. zhang, K.y. Xiao, M. 2nd Dep. Nanjing Univ. of Aeron. and Astron. Nanjing 210016 China

A refined k-Ε model re-considering the fluctuating pressure diffusion term in the dissipation rate equation (Ε-equation) is provided and used in the numerical study of circular semi-confined turbulent impinging jet. The results are compared with those of the standard k-Ε model and show that the predicting ability of the refined k-Ε model is much improved, especially for the turbulent kinetic energy k. So it is necessary to consider the effect of the fluctuating pressure diffusion term and to model this term correctly and exactly in the near wall region with the great adverse pressure gradient, where the effect of the pressure fluctuating is important. Therefore we can conclude that the new modeling idea expressed in this paper is correct and effective.

关键词： Computer simulation jets Mathematical models Turbulence

STUDy ON THE UCST AND LCST IN PHb/ PbHE-SOLVENT SySTEM

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Chinese Chemical Letters 1996年第1期7卷 93-94页

作者： zhang H.F. liu j.y. Wang S.b. Song F.j. Mo z.S. Changchun Inst. of Applied Chemistry Chinese Academy of Sciences Changchun 130022

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关键词： LCST bTUDy ON THE UCST AND LCST IN PHb PbHE-SOLVENT SySTEM

Cenozoic plants from Tibet:An extraordinary decade of discovery,understanding and implications

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Science China Earth Sciences 2023年第2期66卷 205-226页

作者： zhekun zHOU jia liu linlin CHEN Robert A.SPICER Shufeng li jian huang Shitao zHANG yongjiang huang linbo jIA jinjin HU Tao SU CAS Key Laboratory of Tropical Forest Ecology Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesMengla666303China CAS Key Laboratory for Plant Diversity and biogeography of East Asia Kunming Institute of BotanyChinese Academy of SciencesKunming650204China School of Environment Earth and Ecosystem SciencesThe Open UniversityMilton KeynesMK76AAUK Faculty of Land Resource Engineering Kunming University of Science and TechnologyKunming650093China State Key Laboratory of Paleobiology and Stratigraphy Nanjing Institute of Geology and PaleontologyChinese Academy of SciencesNanjing210008China

Plant fossils play an important role in understanding landscape evolution across the Tibetan Region,as well as plant diversity across wider eastern *** the last decade or so,paleobotanical investigations within the Tibet Region have led to a paradigm shift in our understanding of how the present plateau formed and how this affected the regional climate and *** is because:(1)Numerous new taxa have been *** all the Cenozoic records of new plant fossil species reported from the Tibet(Xizang)Autonomous Region 45 out of 63(70%)were documented after *** these,many represent the earliest records from Asia,or in some cases worldwide,at the genus or family level.(2)These fossils show that during the Paleogene,the region now occupied by the Tibetan Plateau was a globally significant floristic exchange *** on paleobiogeographic studies,grounded by fossil evidence,there are four models of regional floristic migration and exchange,i.e.,into Tibet,out of Tibet,out of India and into/out of Africa.(3)Plant fossils evidence the asynchronous formation histories for different parts of the Tibetan *** most of the Paleogene,there was a wide east-west trending valley with a subtropical climate in central Tibet bounded by high(>4 km)mountain systems,but that by the early Oligocene the modern high plateau had begun to form by the rise of the valley *** reconstructions using radiometrically-dated plant fossil assemblages in southeastern Tibet show that by the earliest Oligocene southeastern Tibet(including the Hengduan Mountains)had reached its present elevation.(4)The coevolution between vegetation,landform and paleoenvironment is evidenced by fossil records from what is now the central Tibetan *** the Paleocene to Pliocene,plant diversity transformed from that of tropical,to subtropical forests,through warm to cool temperate woodland and eventually to deciduous shrubland in response to landscape evolution from a seas

关键词： Tibetan Plateau Cenozoic Paleobotany Flora Central valley biodiversity

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