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Magnetic Properties of Ni Nanoparticles and Ni(C) Nanocapsules

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Journal of Materials Science & Technology 2002年第2期18卷 99-100页

作者： z.J.Li G.h.Wen 等 ShenyangNationalLaboratoryforMaterialsScienceandInternationalCentreforMaterialsPhysics InstituteofMetalResearchChineseAcademyofSciencesShenyang110016China DepartmentofPhysics H

Structure and magnetic properties of Ni nanoparticles and Ni(C) nanocapsules were studied. The carbon atoms hardly affect the lattice of Ni to form Ni-C solid solution or nickel carbides. The large thermal irreversibility in zero-field-cooled and zero-field magnetization curves indicates magnetic blocking with a wide energy barrier. Saturation magnetization, remanent magnetization and coercivity of Ni(C) nanocapsules decrease with increasing temperature.

关键词： Nanoparticles Nanocapsules Magnetic properties

Detonation initiation developing from the Richtmyer-Meshkov instability

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Acta Mechanica Sinica 2007年第4期23卷 343-349页

作者： h.h.Teng z.L.Jiang z.M.hu LhD.Institute of Mechanics,CAS.Beijing 100080,China LhD Institute of Mechanics CAS Beijing 100080 China

Detonation initiation resulting from the Richtmyer-Meshkov instability is investigated numerically in the configuration of the shock/spark-induced-deflagration interaction in a combustive gas mixture. Two-dimensional multi-species Navier-Stokes equations implemented with the detailed chemical reaction model are solved with the dispersion-controlled dissipative scheme. Numerical results show that the spark can create a blast wave and ignite deflagrations. Then, the deflagration waves are enhanced due to the Richtmyer-Meshkov instability, which provides detonation initiations with local environment conditions. By examining the deflagration fronts, two kinds of the initiation mechanisms are identified. One is referred to as the deflagration front acceleration with the help of the weak shock wave, occurring on the convex surfaces, and the other is the hot spot explosion deriving from the deflagration front focusing, occurring on the concave surfaces.

关键词： hot spot Deflagration front acceleration Detonation initiation Richtmyer-Meshkov instability

Phase stability,electronic,elastic and thermodynamic properties of Al-RE intermetallics in Mg-Al-RE alloy:A first principles study

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Journal of Magnesium and Alloys 2015年第3期3卷 197-202页

作者： h.L.Chen L.lin P.L.Mao z.Liu School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China

Electronic structure and elastic properties of Al_(2)Y,Al_(3)Y,Al_(2)Gd and Al_(3)Gd phases were investigated by means of first-principles calculations from CASTEP program based on density functional theory(DFT).The ground state energy and elastic constants of each phase were calculated,the formation enthalpy(Δh),bulk modulus(B),shear modulus(G),Young's modulus(E),Poisson's ratio(ν)and anisotropic coefficient(A)were *** formation enthalpy shows that Al_(2)RE is more stable than Al_(3)RE,and Al-Y intermetallics have stronger phase stability than Al-Gd *** calculated mechanical properties indicate that all these four intermetallics are strong and hard brittle phases,it may lead to the similar performance when deforming due to their similar elastic *** total and partial electron density of states(DOS),Mulliken population and metallicity were calculated to analyze the electron structure and bonding characteristics of the ***,phonon calculation was conducted,and the thermodynamic properties were obtained and further discussed.

关键词： First-principles calculation Phase stability Electronic structure Elastic properties Thermodynamic properties

Dynamic experiment and numerical simulation of frozen soil under confining pressure

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Acta Mechanica Sinica 2020年第6期36卷 1302-1318,I0004页

作者： W.R.Tang z.W.zhu T.T.Fu z.W.zhou z.h.Shanggua Applied Mechanics and Structural Safety Key Laboratory of Sichuan Province School of Mechanics and EngineeringSouthwest Jiaotong UniversityChengdu610036China Northwest Institute of Eco-Environment and Resources State Key Laboratory of Frozen Soil EngineeringChinese Academy of SciencesLanzhou730000China

With the development of cold region engineering,it is crucial to study the mechanical properties of frozen *** practice,frozen soil is inevitably subject to impact loading,making the study of frozen soil under impact loading necessary for engineering in cold *** split–hopkinson pressure bar(ShPB)is an important experimental means for obtaining the dynamic performance of *** this study,an ShPB experiment was conducted on frozen soil under confining *** frozen soil exhibited an evident strain rate effect and temperature effect under confining *** ShPB experiment on frozen soil under confining pressure was simulated numerically using LS-DYNA software and the holmquist–Johnson–Cook(hJC)material model.A loading simulation with passive confining pressure and active confining pressure was completed by adding an aluminum sleeve and applying a constant *** simulation results obtained using the above methods were in good agreement with the experimental *** strength of the frozen soil under confining pressure was greater than that of the uniaxial impact,and there was an evident confining pressure ***,the confining pressure provided by passive confinement was larger than that provided by active *** passive confining pressure energy absorption efficiency was higher than for the active confining pressure due to the need to absorb more energy under the same damage *** frozen soil exhibited viscoplastic failure characteristics under confining pressure.

关键词： Frozen soil-Dynamic experiment Confining pressure Split-hopkinson pressure bar Numerical simulation

STRUCTURE AND PROPERTIES OF RE-Ni-B-Al_2O_3 COATING MATERIAL

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Acta Metallurgica Sinica(English Letters) 1997年第1期10卷 56-60页

作者： z.C Guo X.W Yang, h.K lin, z.Y Wang and M. Wang(Department of Metallurgy, Kunming University of Science and Technology Kunming 650093, China) Kunming Univ of Science and Technology Kunming China

The effects of heat treatment temperature on the hardness, wear resistance and structure of a coating material consisting of Ni-0.45wt% RE4.8wt% B-6.2wt% Al2O3 have been discussed. The results showed that the hachess and wear resistance of the composite material reach the optimal values when heating temperature rises to 350℃ and 500℃ respectivelg. X-ray diffraction and scanning electron microscopy indicate that the composite material is amorphous in the as-coating state. The crystallized temperature of Ni-B alloy is increased when RE and Al2O3 particles are inserted. The hardness and wear resistance of the composite are raised obviously with addition of RE and Al2O3 particles.

关键词： RE-Ni-B-Al_2O_3 composite material amorphous structure

MICROSTRUCTURE AND MEChANICAL PROPERTIES OFP/M TiAl ALLOYS AND ThE TEMPERATURE EFFECT

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Acta Metallurgica Sinica(English Letters) 1998年第6期11卷 417-424页

作者： z.M.Sun h.hashimoto S.Sumi Y.h.Park T.Abe z.h.Shan Tohoku Natl Industrial Research Inst Sendai Japan

Two intermetallic compounds of Ti-50at.%Al and Ti-48at.%Al-2at.%Cr were prepared with a mechanical alloying and pulse discharge sintering process. The as-sintered material shows a microstructure of equiaxed gamma grain with sub-micron size. heat treatments in Vacuum at different temperatures up to 1573 K were conducted on the sintered materials. The microstructure of the material coarsened considerably after heat treatment at temperatures higher than 1523 K. The mechanical properties of the as-sintered and the heat treated materials were measured at temperatures up to 973 K, with four-point bending tests. Experimental results indicate that the addition of Cr increases the fracture strength of the intermetallic compound at room temperature and at elevated temperatures as well. The bending fracture strength increases with increasing testing temperature up to about 873 K and a decrease following up. Both fracture strength and fracture strain of the material were found to be improved by heat treatment. (Edited author abstract) 10 Refs.

关键词： titanium aluminide mechanical alloying heat treatment mechanical property temperature

Synthesis of self-assembled nanorod vanadium oxide bundles by sonochemical treatment

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Journal of Natural Gas Chemistry 2009年第3期18卷 312-318页

作者： Y.h.Taufiq-Yap Y.C.Wong z.zainal M.z.hussein Centre of Excellence for Catalysis Science and Technology Faculty of ScienceUniversiti Putra Malaysia Department of Chemistry Faculty of ScienceUniversiti Putra Malaysia

Self-assembled nanorod of vanadium oxide bundles were synthesized by treating bulk V2O5 with high intensity sonochemical technique. The synthesized materials were characterized by X-ray diffraction （XRD）, scanning electron microscope （SEM）, transmission electron microscope （TEM） and temperature-programmed reduction （TPR） in h2. Catalytic behaviour of the materials over anaerobic n-butane oxidation was studied through temperature-programmed reaction （TPRn）. Catalytic evaluation of the sonochemical treated V2O5 products was also studied on microreactor. XRD patterns of all the vanadium samples were perfectly indexed to V2O5. The morphologies of the nanorod vanadium oxides as shown in SEM and TEM depended on the duration of the ultrasound irradiation. Prolonging the ultrasound irradiation duration resulted in materials with uniform, well defined shapes and surface structures and smaller size of nanorod vanadium oxide bundles. h2-TPR profiles showed that larger amount of oxygen species were removed from the nanorod V2O5 compared to the bulk. Furthermore, the nanorod vanadium oxide bundles, which were produced after 90, 120 and 180 min of sonochemical treatment, showed an additional reduction peak at lower temperature （-850 K）, suggesting the presence of some highly active oxygen species. TPRn in n-butane/he over these materials showed that the nanorod V2O5 with highly active oxygen species showed markedly higher activity than the bulk material, which was further proven by catalytic oxidation of n-butane.

关键词： nanorod vanadium oxide sonochemical treatment butane oxidation

STUDY ON MORPhOLOGY OF ChROMIUM IN ChILLED Cu-0.14%-2.0%Cr ALLOYS

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Acta Metallurgica Sinica(English Letters) 2004年第5期17卷 655-660页

作者： h.W.Yang z.K.Fan SchoolofMaterialScienceandEngineering Xi＇anUniversityofTechnologyXi＇an710048China SchoolofMaterialScienceandEngineering Xi＇anUniversityofTechnologyXi＇an710048China

The morphology of chromium in chilled Cu-Cr alloys with 0.14%-2.0% Cr has been studied. The results showed that eutectic Cr phase takes a fibrous shape, and pre-eutectic Cr is dendritic in the studied chilled Cu-Cr alloy. During solute treatment of the eutectic and super-eutectic Cu-Cr alloys, only part of chromium particles dissolved in copper phase, some fiber and dendritic chromium still remained. Forging before solute treatment can reduce the size of primary Cr particles, which benefits the aging structure.

关键词： morphology of Cr Cu-Cr alloy chilling forging

INVESTIGATION OF LASER BEAM WELDING PROCESS OF Az61 MAGNESIUM-BASED ALLOY

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Acta Metallurgica Sinica(English Letters) 2006年第4期19卷 287-294页

作者： h.Y. Wang z.J. Li Industrial Center Shenzhen Polytechnic Shenzhen 518055 China

Laser welling process of Az61 magnesium alloys is investigated using a special CO2 laser experimental system. The effect of processing parameters including laser power, welling speed, and protection gas flow at the top and bottom is researched. The results show that an ideal well bead can be formed by choosing the processing parameters properly. An optimized parameter range is obtained by a large number of experiments. Among them, laser power and welling speed are the two main parameters that determine the well width and dimensions. The protect gas flow rate has a slight effect on the well width, but it directly effects the surface color of the well. The test results for typical welds indicate that the microhardness and tensile strength of the well zone are better than that of the base metal A fine-grained well region has been observed and no obvious heat-affected zone is found. The well zone mainly consists of small α-Mg phase, （α ＋ Al12Mg17）, and other eutectic phases. The small grains and the eutectic phases in the joint are believed to play an important role in the increase of the strength of wells for Az61 magnesium alloys.

关键词： magnesium alloy laser beam welding laser power welling speed