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self-propagating high temperature synthesis of Mosi_2 matrix composites

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Rare Metals 2006年第3期25卷 225-230页

作者： Akhtar Farid s.h. Islam Materials science and Engineering s.h.ol State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China

Mosi2 is presently regarded as the most important material for electrical heating and as one with huge potential for high temperature structural uses. Mosi2 and Mosi2 matrix composites were prepared by self-propagating high temperature synthesis （shs）. Pure Mosi2 was obtained and a compound of Mosi2 and Wsi2was synthesized in the form of predominant solid solution （Mo,W）si2. By adding aluminum of 5.5 at.% to Mo-si, the crystal structure of Mosi2 changed into a mixture of tetragonal Cllb Mosi2and hexagonal C40 Mo（si,Al）2. The （Mo,W）si2-Mo（si,Al）2-W（si,Al）2 composite materials were synthesized by adding aluminum of 5.5 at.% to Mo-W-si. however, if the amount of the added aluminum was not larger than 2.5 at.%, it did not have any significant effect. shs is an effective technology for synthesis of Mosi2 and Mosi2 matrix composites.

关键词： powder metallurgy Mosi2 matrix composites self-propagating high temperature synthesis molybdenumtungsten disilicide molybdenum aluminosilicide

Ideals Whose First Two Betti Numbers Are Close

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Algebra Colloquium 2015年第4期22卷 671-676页

作者： Keivan Borna s.h. hassanzadeh Faculty of Mathematical sciences and Computer Kharazmi University Tehran Iran School of Mathematics Institute for Research in Fundamental Sciences (IPM) Tehran Iran Faculty of Mathematical sciences and Computer Kharazmi University Tehran Iran Institute of Mathematics Universidade Federal de Rio de Janeiro Brasil

For an ideal I of a Noetherian local ring （R, m, k） one hasβR1（I） -β0R（I） ≥-1. It is demonstrated that some residual intersections of an ideal I for whichβ1R（I） -β0R（I） = -1 or 0 are perfect.

关键词： Betti numbers linlkage theory perfect Gorenstein ideals residual intersection

Investigation of Micro Formability of Bulk Amorphous Alloy in the supercooled Liquid state Based on Fluid Flow and Finite Element Analysis

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Journal of Materials science & Technology 2009年第2期25卷 277-280页

作者： M. Cheng s.h. Zhang Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

Research results on the viscous flow deformation behavior of bulk amorphous alloy in different systems are reviewed. The material exhibits an ideal Newtonian fluid at a high temperature. Analytical solution of lamellar fluid flow behavior is used to discuss the viscous flow behavior of the bulk amorphous alloy in the supercooled liquid state. A material model, which describes such deformation behavior of Mg6oCusoYlo amorphous alloy, is introduced into the finite element method of microformin8 process. surface feature size was investigated and found not sensitive to the micro formability. Bulk amorphous alloy may possibly be applied to microelectro-mechanical-systems （MEMs） fabrication.

关键词： Bulk amorphous alloy supercooled liquid state Micro formability Lamellar fluid flow

CFD-DEM simulation of a pseudo-two-dimensional spouted bed comprising coarse particles

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Particuology 2019年第2期17卷 171-180页

作者： B. Mahmoodi s.h. hosseini G. Ahmadi llam Gas Treating Company llam Iran Department of Chemical Engineering llam University llam 69315-516 Iran Department of Mechanical and Aeronautical Engineering Clarkson University Potsdam NY 13699-5725 USA

In the present study, computational fluid dynamics (CFD) and the discrete element method (DEM) are used in conjunction with the Eulerian-Lagrangian method to simulate a pseudo-two-dimensional spouted bed comprising coarse 6-mm particles. The open-source OpenFOAM code is used to solve the governing equations. The predicted vertical particle velocity along the bed axis, particle velocity profiles in the radial directi on, power spectral den sity, time-averaged particle velocity vectors, bed pressure drop, and solid flow pattern are evaluated and compared with existing experimental data. Good agreement is found between the CFD-DEM results and the measured data. It is also shown that the present CFD-DEM model accurately predicts the particle flow pattern throughout the bed. It is found that the drag force, solid stresses, and gravity play important roles in the CFD-DEM simulation of a spouted bed comprising coarse particles.

关键词： CFD-DEM Pseudo-2D spouted bed hydrodynamics Coarse particles

Mathematical modeling and simulation of the interface region of a tri-layer composite material,brass-steel-brass,produced by cold rolling

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International Journal of Minerals,Metallurgy and Materials 2009年第2期16卷 189-196页

作者： h. Arabi s.h. seyedein A. Mehryab B. Tolaminejad s.h.ol of Metallurgy and Materials Engineering Iran University of Science and TechnologyIUSTNarmakTehranIran

The object of this study was to find the optimum conditions for the production of a sandwich composite from the sheets of brass-steel-brass. The experimental data obtained during the production process were used to validate the simulation program, which was written to establish the relation between the interface morphology and the thickness reduction amount of the composite. For this purpose, two surfaces of a steel sheet were first prepared by scratching brushing before inserting it between two brass sheets with smooth surfaces. Three sheets were then subjected to a cold rolling process for producing a tri-layer composite with various thick- nesses. The sheet interface after rolling was studied by different techniques, and the bonding strength for each rolling condition was determined by peeling test. Moreover, a relation between interfacial bonding strength and thickness reduction was found. The simulation results were compared with the experimental data and the available theoretical models to modify the original simulation program with high application efficiency used for predicting the behavior of the interface under different pressures.

关键词： sandwich composite cold rolling mathematical simulation metallic bonding interface

EMBRITTLEMENT OF A Cr-Mo LOW-ALLOY sTEEL DUE TO LOW-TEMPERATURE NEUTRON IRRADIATION

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Acta Metallurgica sinica(English Letters) 2006年第1期19卷 20-26页

作者： s.h. song L. Q. Weng Department of Materials science and Engineering Shenzhen Graduate School HarbinInstitute of Technology Shenzhen 518055 China

Embrittlement of a Cr-Mo2.25CrlMo steel stemming from neutron irradiation at 270℃ is studied by virtue of small punch testing in conjunction with scanning electron microscopy. The ductile-brittle transition temperature determined by the small punch test is much lower than that determined by the standard Charpy test. There is some irradiation-induced embrittlement effect after the steel is irradiated for 46 days with a neutron dose rate of 1.05×10^18dpa/s （displacement per atom per second）.

关键词： irradiation embrittlement segregation low alloy steels pressure vessel

Effect of solid solution supersaturation on Precipitation of γ′ in Rapidly Quenched Ni-Al Binary Alloys

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Journal of Materials science & Technology 2009年第1期25卷 130-134页

作者： A. samadi A. Abdollah-zadeh s. Behrouzghaemi s.h. Razavi Department of Materials Engineering Tarbiat Modarres University P.O. Box 14115-143 Tehran Iran Department of Materials and Metallurgical Engineering Iran University of Science and Technology (IUST) Narmak#16846 Tehran Iran

The effect of solid solution supersaturation on the precipitation of γ＇ in rapidly quenched Ni-AI binary alloys containing 11.6, 14.2 and 16.5 at. pct AI was investigated. The samples were solutioned at 1250℃, quenched in iced brine, and then analyzed by electron microscopy and XRD （X-ray diffraction） techniques. In Ni-11.6 at. pct Al alloy, ordering and phase separation took place simultaneously, resulting in a uniform distribution of γ＇. A transition from uniform to bimodal γ＇ phase distribution occurred in the composition range between 14.2 and 16.5 at. pct Al. This transition was accompanied by changes in the morphology of γ＇ precipitates. The microstructural observations were discussed in view of both kinetics and crystallographic considerations.

关键词： Ni-Al system heat treatment γ' precipitation Lattice mismatch

CORROsION BEhAVIOR OF A ZIRCONIUM-TITANIUM BAsED PhOs.h.NIC ACID CONVERsION COATING ON AA6061 ALUMINIUM ALLOY

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Acta Metallurgica sinica(English Letters) 2008年第4期21卷 269-274页

作者： s.h. Wang C.s. Liu F.J. shan Key Laboratory for Anisotropy and Texture of Materials Ministry of Education Northeastern University Shenyang 110004 China Material ＆ Chemical Engineering College Liaoning University of Technology Jinzhou 121001 China

The conversion coating was formed by dipping AA6061 in a fluorotitanate/zirconate acid and amino trimethylene phos.h.nic acid （ATMP） solution at room temperature. The formation process and the anti-corrosion performance of the conversion coating were investigated using electrochemical test and salt spray test （ssT）, respectively. The electrochemical test shows that the Zr/Ti and ATMP coating improves the corrosion resistance of AA6061 as good as the chromate （VI） coating. But the results of ssT show that the corrosion resistance of Zr/Ti and ATMP coating is not as good as the chromate （VI） coating. The corrosion area is less than 2% after 72 h.

关键词： Corrosion resistance Fluorotitanate/zireonate acid Phos.h.nic acid Aluminium alloy Conversion coating

Free vibration and transient response of double curved beams connected by intermediate straight beams

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 37-62页

作者： R.A.JAFARI-TALOOKOLAEI h.GhANDVAR E.JUMAEV s.KhATIR T.CUONG-LE s.h.ol of Mechanical Engineering Babol Noshirvani University of Technology Department of Mechanical Engineering Faculty of Engineering New Uzbekistan University University of Business and science Center for Engineering Application and Technology solutions Ho Chi Minh City Open University

This paper investigates the free vibration and transient response of interconnected structures including double curved beams and intermediate straight beams,which are all constructed from functionally graded porous(FGP) materials. The strain potential and kinetic energies of each beam along with the work done by the external force are calculated. Additionally, a higher-order beam element is introduced to derive stiffness and mass matrices, along with the force vector. The curved and straight beams are discretized, and their assembled stiffness, mass matrices, and force vectors, are *** conditions at the joints are used to derive the total matrices of the entire structure. subsequently, the natural frequencies and transient response of the system are determined. The accuracy of the mathematical model and the self-developed computer program is validated through the comparison of the obtained results with those of the existing literature and commercial software ANsYs, demonstrating excellent ***, a comprehensive study is conducted to investigate the effects of various parameters on the free vibration and transient response of the considered structure.

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