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Unsteady three-dimensional MHD flow of the micropolar fluid over an oscillatory disk with Cattaneo-Christov double diffusion

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Applied Mathematics and Mechanics(English Edition) 2019年第10期40卷 1471-1486页

作者： A.RAUF S.A.SHEHzAD z.ABBAS t.HAYAt Department of Mathematics COMSATS University Islamabad Sahiwal 57000 Pakistan Department of Mathematics The Islamia University of Bahawalpur Bahawalpur 63100 Pakistan Department of Mathematics Quiad-i-Azam University Islamabad 44000 Pakistan

Cattaneo-Christov heat and mass flux models are considered rather than Fourier and Fick laws due to the presence of thermal and concentration transport hyperbolic phenomena. the generalized form of the Navier-Stokes model is considered in hydromagnetic flow. three-dimensional (3D) unsteady fluid motion is generated by the periodic oscillations of a rotating disk. Similarity transformations are used to obtain the normalized fluid flow model. the successive over relaxation (SOR) method with finite difference schemes are accomplished for the numerical solution of the obtained partial differential non-linear system. the flow features of the velocity, microrotation, temperature, and concentration fields are discussed in pictorial forms for various physical flow parameters. the couple stresses and heat and mass transfer rates for different physical quantities are explained via tabular forms. For better insight of the physical fluid model, 3D fluid phenomena and two-dimensional (2D) contours are also plotted. the results show that the micropolar fluids contain microstructure having non-symmetric stress tensor and are useful in lubrication theory. Moreover, the thermal and concentration waves in Cattaneo-Christov models have a significance role in the laser heating and enhancement in thermal conductivity.

关键词： three-dimensional (3D) flow micropolar fluid magnetohydrodynamics (MHD) Cattaneo-Christov theory oscillatory disk

Magnetization reversal of antiferromagnetically coupled perpendicular anisotropy films driven by current

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Journal of Materials Science & technology 2018年第5期34卷 832-835页

作者： X.t.zhao Y.Q.zhao W.Liu z.M.Dai t.t.Wang X.G.zhao z.D.zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

By inserting an ultrathin Pt layer at Co/Ru interface,we established antiferromagnetic coupling with outof-plane magnetization in Co/Ru/Co film stacks fabricated by *** achieve configuration suitable for free layer,the magnetic properties of the stacks have been investigated by changing the thickness of Co,Ru and Pt layers using an orthogonal wedges *** is found that magnetic properties for upper Co layer thinner than 0.5 nm are sensitive to little change in Ru *** continuity of upper Co layer by slightly increasing the thickness can effectively increase the squareness of minor *** switching magnetization of synthetic antiferromagnetic（SAF） structure is achieved by DC current under an in-plane static magnetic field of ± 500 *** structure is very promising for free layer in spintronic application.

关键词： Magnetic materials Multilayer structure Wedge Exchange coupling Antiferromagnetic

Remarkably high fracture toughness of HfNbtatizr refractory high-entropy alloy

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Journal of Materials Science & technology 2022年第28期123卷 70-77页

作者： X.J.Fan R.t.Qu z.F.zhang Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Nano Science and technology Institute University of Science and Technology of ChinaSuzhou 215132China

High-entropy alloys(HEAs)with face-centered cubic(FCC)phase such as CoCrFeMnNi or CoCrNi generally exhibit ultra-high fracture toughness but relatively low *** contrast,body-centered cubic(BCC)HEAs often display higher strengths,but the few reports on fracture toughness measurement demonstrate low toughness *** we show that the BCC HfNbtatizr refractory HEA,which possesses a combination of high strength,good tensile ductility and excellent high-temperature properties,also exhibits a remarkably high fracture *** using the"single specimen"compliance method for J-integral measurement according to the AStM E1820–17 standard,its fracture toughness K_(JIC)was experimentally determined to be 210 MPa m^(1/2),which renders this HEA among the toughest metallic *** excellent damage tolerance makes the HEA promising for applications as high-temperature structural materials such as in aerospace field.

关键词： High-entropy alloys BCC structure Fracture toughness J-integral

Magneto optics and time resolved terahertz spectrocopy

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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

ISOCHRONOUS StRESS-StRAIN CURVES OF LOW ALLOY StEEL CROSS-WELD-SPECIMEN At HIGH tEMPERAtURE

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 612-617页

作者： C.W.Ma F.z.Xuan z.D.Wang S.t.tu East China University of Science and technology Shanghai 200237 ChinaEast China University of Science and Technology Shanghai 200237 ChinaEast China University of Science and Technology Shanghai 200237 ChinaEast China University of Science and Technology Shanghai 200237 China Nanjing University of Technology Nanjing 210009 China

In this work, a parametric approach is presented and utilized to determine the creep properties of weldments; then the model of creep strain for cross weld specimen is given. On the basis of the experimental results, attempt has been made to establish equations of the isochronous stress-strain for weld joint that can predict the function of loading and service time in use of the creep data of base metal and weld metal.

关键词： isochronous stress-strain curve creep deformation high temperature welded joint low alloy steel

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

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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

PREDICtION OF CARBON CONCENtRAtION AND FERRItE VOLUME FRACtION OF HOt-ROLLED StEEL StRIP DURING LAMINAR COOLING

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Acta Metallurgica Sinica(English Letters) 2007年第4期20卷 251-257页

作者： Y.t. zhang C.z. Wang D.z. Li Y.Y. Li School of Material Science and Engineering Shenyang Ligong University Shenyang 110168 China Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

A phase transformation model was presented for predicting the phase fraction transformed and the carbon concentration in austenite for austenite to ferrite transformation during laminar cooling on run-out table in hot rolling strip mill. In this model, the parameter k in Avrami equation was developed for carbon steels. the wide range of chemical composition, the primary austenite grain size, and the retained strain were taken into account. It can be used to predict the ferrite volume fraction and the carbon concentration in austenite of hot-rolled steel strip during laminar cooling on run-out table. the coiling temperature controlling model was also presented to calculate the temperature of steel strip. the transformation kinetics of austenite to ferrite and the evolution of carbon concentration in austenite at different temperatures during cooling were investigated in the hot rolled Q235B strip for thickness of 9.35, 6.4, and 3.2mm. the ferrite volume fraction along the length of the strip was also calculated. the calculated ferrite volume fraction was compared with the log data from hot strip mill and the calculated results were in agreement with the experimental ones. the present study is a part of the prediction of the mechanical properties of hot-rolled steel strip, and it has already been used on-line and off-line in the hot strip mill.

关键词： carbon concentration ferrite volume fraction laminar cooling hot rolling

High-performance multilayer WSe2 field-effect transistors with carrier type control

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Nano Research 2018年第2期11卷 722-730页

作者： Pudasaini, Pushpa Raj Oyedele, Akinola zhang, Cheng Stanford, Michael G. Cross, Nicholas Wong, Anthony t. Hoffman, Anna N. Xiao, Kai Duscher, Gerd Mandrus, David G. ward, thomas z. Rack, Philip D. Department of Materials Science and Engineering University of Tennessee Knoxville USA Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak Ridge USA Bredesen Center for Interdisciplinary Research and Graduate Education University of Tennessee Knoxville USA Materials Science and technology Division Oak Ridge National Laboratory Oak Ridge USA

In this stud high-performance multilayer WSe2 field-effect transistor （FEt） devices with carrier type control are demonstrated via thickness modulation and a remote oxygen plasma surface treatment. Carrier type control in multilayer WSe2 FEt devices with Cr/Au contacts is initially demonstrated by modulating the WSe2 thickness. the carrier type evolves with increasing WSe2 channel thickness, being p-type, ambipolar, and n-type at thicknesses 〈 3, - 4, and 〉 5 nm, respectively. the thickness-dependent carrier type is attributed to changes in the bandgap of WSe2 as a function of the thickness and the carrier band offsets relative to the metal contacts. Furthermore, we present a strong hole carrier doping effect via remote oxygen plasma treatment. It non-degenerately converts n-type characteristics into p-type and enhances field-effect hole mobility by three orders of magnitude. this work demonstrates progress towards the realization of high-performance multilayer WSe2 FEts with carrier type control, potentially extendable to other transition metal dichalcogenides, for future electronic and oDtoelectronic alpplications.

关键词： transition metaldichalcogenide field-effect transistors carrier control plasma treatment carrier mobility

Intrinsic Strength Asymmetry Between tension and Compression of Perfect Face-Centered-Cubic Crystals

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Acta Metallurgica Sinica(English Letters) 2016年第8期29卷 755-762页

作者： R.F.Wang J.Xu R.t.Qu z.Q.Liu z.F.zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

the strength asymmetry between tension and compression is a typical case of mechanical response of *** we achieve the intrinsic strength asymmetry of six face-centered-cubic perfect crystals（Cu,Au,Ni,Pt,Al and Ir）through calculating the ideal tensile and compressive strength with considering the normal stress effect and the competition between different crystallographic *** results show that both the intrinsic factors（the ideal shear strength and cleavage strength of low-index planes）and the orientation could affect the strength asymmetry,which may provide insights into understanding the strength of ultra-strong materials.

关键词： Perfect crystal Strength asymmetry tension Compression