检索结果-南通市图书馆

ThE COUPLED FEM ANALYSIS OF ThE TRANSIENT TEMPERATURE FIELD DURING INERTIA FRICTION WELDING OF Gh4169 ALLOY

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2007年第4期20卷 301-306页

作者： L.W. Zhang j.B. Pei Q.Z. Zhang C.D. Liu W.h. Zhu S. Qu j.h. Wang The State Key Laboratory for Materials Modification by Laser Ion and Electron Beams Dalian University of Technology Dalian 116023 China School of Materials Science and Engineering Dalian University of Technology Dalian 116023 China Shenyang Li Ming Aero-Engine Group Corporation Shenyang 110043 China

The inertia friction welding process is a non-linear process because of the interaction between the temperature field and the material properties as well as the friction force. A thermo-mechanical coupled finite element model is established to simulate the temperature field of this process. The transient temperature distribution during the inertia friction welding process of two similar workpieces of Gh4169 alloy is calculated. The region of the circular cross-section of the workpiece is divided into a number of four-nodded isoparametric elements. In this model, the temperature dependent thermal properties, time dependent heat inputs, contact condition of welding interface, and deformation of the flash were considered. At the same time, the convection and radiation heat losses at the surface of the workpieces were also considered. A temperature data acquisition system was developed. The temperature at some position near the welding interface was measured using this system. The calculated temperature agrees well with the experimental data. The deformation of the flash and the factor affecting the temperature distribution at the welding interface are also discussed.

关键词： inertia friction welding temperature field numerical simulation finite element method

Superplasticity of fine-grained Mg-10Li alloy prepared by severe plastic deformation and understanding its deformation mechanisms

在线全文

学校读者我要写书评

暂无评论

journal of Magnesium and Alloys 2024年第1期12卷 316-331页

作者： h.T.jeong S.W.lee W.j.Kim Department of Materials Science and Engineering Hongik UniversityMapo-guSangsu-dong 72-1Seoul 121-791Republic of Korea

The superplastic behavior and associated deformation mechanisms of a fine-grained Mg-10.1 Li-0.8Al-0.6Zn alloy(LAZ1011)with a grain size of 3.2μm,primarily composed of the BCCβphase and a small amount of the hCPαphase,were examined in a temperature range of 473 K to 623 *** microstructural refinement of this alloy was achieved by employing high-ratio differential speed *** best superplasticity was achieved at 523 K and at strain rates of 10^(-4)-5×10^(-4)s^(-1),where tensile elongations of 550±600%were *** the heating and holding stage of the tensile samples prior to tensile loading,a significant increase in grain size was observed at temperatures above 573 ***,it was important to consider this effect when analyzing and understanding the superplastic deformation behavior and *** the investigated strain rate range,the superplastic flow at low strain rates was governed by lattice diffusion-controlled grain boundary sliding,while at high strain rates,lattice diffusion-controlled dislocation climb creep was the rate-controlling deformation *** was concluded that solute drag creep is unlikely to *** the late stages of deformation at 523 K,it was observed that grain boundary sliding led to the agglomeration of theαphase,resulting in significant strain *** mechanism maps were constructed forβ-Mg-Li alloys in the form of 2D and 3D formats as a function of strain rate,stress,temperature,and grain size,using the constitutive equations for various deformation mechanisms derived based on the data of the current tests.

关键词： Magnesium-lithium alloy Superplasticity Severe plastic deformation Grain size Grain growth

Fabrication of ultrafine Nd-Fe-B powder by a modified reduction-diffusion process

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2006年第z2期25卷 223-226页

作者： jANG T.S. lee D.h. ChOI C.j. SEO W.S. lee Y.h. Department of Electronic Materials Engineering Sunmoon University Korea Powder Materials Research Center Korea Institute of Machinery and Materials Korea Advanced Materials Analysis & Evaluation Center Korea Institute of Ceramic Engineering and Technology Korea

In order to obtain ultrafine Nd-Fe-B powder, a spray-dried precursor was treated by reduction-diffusion (R/D) process. And, unlike the conventional R/D process, calcium reduction that is a crucial step for the formation of Nd2Fe14B was performed without conglomerating the precursor with Ca powder. By adopting this modified process, it is possible to synthesize the hard magnetic Nd2Fe14B at the reaction temperature as low as 850 ℃. The average size of Nd2Fe14B particles that are uniformly distributed in the optimally treated powder was h thin layers of Nd-rich phase. Typical magnetic properties of such powder without eliminating impurity CaO were ihc=～5.9 kOe, Br=～5.5 kG, and (Bh)max=～6 MGOe.

关键词： NdFeB powder spray drying reduction-diffusion process Nd2Fe14B magnetic powder

A COMPUTERIZED SYSTEM ON KINETIC ANALYSIS AND EVALUATION OF GAS/SOLID REACTIONS

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2003年第6期16卷 495-506页

作者： j.h. Liu, j. Y. Zhang and S.K. WeiSchool of Metallurgical and Ecological Engineering, University of Science & Technology Beijing, Beijing 100083, China School of Metallurgical and Ecological Engineering University of Science & Technology Beijing

The present paper presents the structure, features and functions of a computerized system on kinetic analysis and evaluation of gas/solid reactions, KinPreGSR. Kin-PreGSR is a menu driven system, can be operated with MS Windows as workbench in a PC computer. It has been developed using visual C++ with FoxPro hybrid coding technique.KinPreGSR combines the characteristics of gas/solid reactions with the kinetic models as well as mass and heat transfer equations. The database files were established for the apparent activation energies of some reduction and decomposition reactions to allow the prediction of the reaction kinetics to some extents. Outputs can be displayed using graphical or numerical forms. Examples regarding the oxide reduction and carbonate decomposition under isothermal conditions are given to show those functions.

关键词： gas/solid reaction kinetics computer system evaluation anal-ysis

Ω and φ in Au + Au collisions at (s_(NN))^(1/2)= 200 and 11.5 GeV from a multiphase transport model

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2017年第8期41卷 71-77页

作者： Y. j. Ye j.h. Chen Y.G. Ma S.Zhang C. Zhong Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 China University of Chinese Academy of Sciences Beijing 100049 China ShanghaiTech. University Shanghai 200031 China

Within the framework of a multiphase transport model, we study the production and properties of Ω andφ in Au ＋ Au collisions with a new set of parameters for （s（NN））^（1/2）= 200 GeV and with the original set of parameters for （s（NN））^（1/2）= 11.5 GeV. The AMPT model with string melting provides a reasonable description at （s（NN））^（1/2）= 200 GeV,while the default AMPT model describes the data well at （s（NN））^（1/2）= 11.5 GeV. This indicates that the system created at top RhIC energy is dominated by partonic interactions, while hadronic interactions become important at lower beam energy, such as （s（NN））^（1/2）= 11.5 GeV. The comparison of N（Ω^＋＋Ω^-）/[2N（φ）] ratio between data and calculations further supports the argument. Our calculations can generally describe the data of nuclear modification factor as well as elliptic flow.

关键词： multi-strangeness particles AMPT RhIC

A transmission electron microscopy study of microscopic causes for localized-corrosion morphology variations in the AA7055 Al alloy

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

journal of Materials Science & Technology 2018年第10期34卷 1719-1729页

作者： X.B. Yang j.h. Chen G.h. Zhang L.P. huang T.W. Fan Y. Ding X.W. Yu Center for high-Resolution Electron Microscopy College of Materials Sdence and Engineering Hunan University Changsha Hunan 410082 China Department of Applied Physics School of Physics and Electronics Hunan University Changsha Hunan 410082 China

By Using （scanning） transmission electron microscopy, localized-corrosion morphology variations of the AA7055 AIZn（Cu）Mg alloy with different thermal processes and their underlying microscopic causes were investigated systematically. Our study shows that the corrosion resistance of the nanoscale precipitates varies with their structure type and Cu-content. just like the Al-matrix, the early-stage precipitates are corrosion resistant, as compared with the ηp/η-precipitates without high Cu-content. With a high Cu-content, however, the η-precipitates become most corrosion resistant among all phases involved. hence, tailoring the precipitate microstructure and chemistry though thermal processes may change the overall corrosion morphology and improve corrosion resistance property of the alloy.

关键词： Aluminum alloys Precipitates Corrosion Electron microscopy

Welcome to our new Editorial Board Members of the journal of Infrared and Millimeter Waves at 60th anniversary of SITP and happy new year 2019

在线全文

学校读者我要写书评

暂无评论

红外与毫米波学报 2019年第1期38卷 1-2页

作者： M.h. Zhang h. Shen Z.X. Li X. Liu j.h. Chu 不详

It is a great honor to introduce *** hu and *** Du as our new Editorial Board Member of the journal of Infrared and Millimeter Waves at 60th anniversary of the Shanghai Institute of Technical Physics(SITP)of the Chinese Academy of *** celebrated its 60th year of existence on October 28,2018,with a scientist and engineer academic conference to commemorate the six decades of its history,to honor the six decades that SITP has devoted to developing science and technology in frontier areas of infrared *** was cofounded by CAS and Fudan University on October 28,1958.

关键词： Editorial Board Members SITP

A Proposed Core Catcher System and Thermite Experimental Results

在线全文

学校读者我要写书评

暂无评论

journal of Energy and Power Engineering 2011年第11期5卷 1005-1014页

作者： h.Y. Kim j.h. Kim K.S. ha j.h. Song j.h. Park Thermal hydraulics Safety Research Division Korea Atomic Energy Research Institute Daejeon 305-353 Korea

To prevent direct contact of the melt and basemat concrete of the cavity in a postulated core melt accident, a core catcher concept is suggested. Upon ablation of the sacrificial layer on top of the core catcher while molten core material is discharged, a mixture of water and gas is injected from below. It is expected that a simultaneous injection of water and gas could prevent a possible steam explosion/spike and also suppress the rapid release of steam which might result in fast over-pressurization of the containment. A test facility for the core catcher using a thermite reaction technique for the generation of the melt was designed and constructed at Korea Atomic Energy Research Institute （KAERI）. The first series of tests were performed by using a mixture of Al, Fe2O3, and CaO as a stimulant. As a first try, only water was injected from the bottom of the melt through five water injection nozzles when the melt front reached the water injection nozzles. A description of the test facility for the core catcher, the thermite composition, and the methods of experiment is included. The test results are discussed.

关键词： Core catcher corium cooling sacrificial layer water injection severe accidient thermite reaction.

Design of small-area multi-bit antifuse-type 1 kbit OTP memory

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

journal of Central South University 2009年第3期16卷 467-473页

作者：李龙镇 lee j.h.KIM T h jIN K h PARK M h hA P B KIM Y h Department of Electronic Engineering Changwon National University Department of Computer Science and Technology Yanbian University

A multi-bit antifuse-type one-time programmable （OTP） memory is designed, which has a smaller area and a shorter programming time compared with the conventional single-bit antifuse-type OTP memory. While the conventional antifuse-type OTP memory can store a bit per cell, a proposed OTP memory can store two consecutive bits per cell through a data compression technique. The 1 kbit OTP memory designed with Magnachip 0.18 μm CMOS （complementary metal-oxide semiconductor） process is 34% smaller than the conventional single-bit antifuse-type OTP memory since the sizes of cell array and row decoder are reduced. And the programming time of the proposed OTP memory is nearly 50% smaller than that of the conventional counterpart since two consecutive bytes can be compressed and programmed into eight OTP cells at once. The layout area is 214 μm× 327 μ,, and the read current is simulated to be 30.4 μA.

关键词： multi-bit OTP programming time antifuse memory data compression