检索结果-南通市图书馆

Determination of phase equilibria in the Ni-Ta-Zr system at 1223 K

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2003年第3期22卷 160-163页

作者： PAN Ximiao and JIN ZhanpengPhase Diagram and materials Design Center, school of materials science and engineering, Central South University, Changsha 410083, china Phase Diagram and materials Design Center School of Materials Science and Engineering Central South University Changsha 410083

The phase equilibrium relations of the ternary Ni-Ta-Zr system at 1223 K wereinvestigated by means of diffusion triple and electron probe microanalysis (EPMA) techniques. Twoternary compounds were found and a series of tie lines and tie triangles have been determined. Themaximum solubility of Ta in NiZr_2 is about 13.5% (atom fraction). The corresponding tentativeisothermal section at this temperature was constructed based on current experimental information.

关键词： phase diagram diffusion triple nickel EPMA Ni-Ta-Zr system

High-temperature oxidation behavior of Al_2O_3/TiAl matrix composite in air

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2009年第5期52卷 1273-1282页

作者： AI TaoTao1,WANG Fen2 & FENG XiaoMing1 1 Department of materials science and engineering,Shaanxi University of Technology,Hanzhong 723003,china 2 school of materials science and engineering,Shaanxi University of science and Technology,Xi’an 710021,china 1. Department of materials science and engineering Shaanxi University of Technology Hanzhong 723003 China 2. school of materials science and engineering Shaanxi University of Science and Technology Xi’an 710021 China

The oxidation behavior of Al2O3/TiAl in situ composites fabricated by hot-pressing technology was in-vestigated at 900℃ in static *** results indicate that the mass gains of the composites samples decrease gradually with increasing Nb2O5 content and the inert Al2O3 dispersoids effectively increase the oxidation resistance of the *** higher the Al2O3 dispersoids content,the more pro-nounced the *** primary oxidation precesses obey approximately the linear laws,and the cyclic oxidation precesses follow the parabolic *** oxidized sample containing Ti2AlN and TiAl phases in the scales exhibits excellent oxidation *** oxide scale formed after exposure at 900 ℃ for 120 h is multiple-layered,consisting mainly of an outer TiO2 layer,an intermediate Al2O3 layer,and an inner TiO2+Al2O3 mixed *** the outer layer to the inner layer,TiO2+Al2O3 mixed layer presents the transit of Al-rich oxide to Ti-rich oxide mixed *** the substrate,cross-section micrograph shows a relatively loose layer,and micro-and macro-pores remain on this layer,which is a transition layer and transferres from Al2O3+TiO2 scale to *** thickness of oxide layer is about 20 μ*** is also found that continuous protective alumina scales can not be observed on the surface of oxida-tion *** ions diffuse outwardly to form the outer TiO2 layer,while oxygen ions transport inwardly to form the inner TiO2+Al2O3 mixed *** long-time intensive oxidation exposure,the internal Al2O3 scale has a good adhesiveness with the outer TiO2 *** obvious spallation of the oxide scales *** increased oxidation resistance by the presence of in situ Al2O3 particulates is at-tributed to the enhanced alumina-forming tendency and thin and dense scale ***2O3 particu-lates enhance the potential barrier of Ti ions from M/MO interface to O/MO interface,thereby the TiO2 growth rate decreases,which is also beneficial to improve the oxidation resistance.

关键词： Al2O3/TiAl matrix composite oxidation resistance high temperature

Effects of Na/K ratio on the phase structure and electrical properties of Na_xK_(1-x)NbO_3 lead-free piezoelectric ceramics

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2010年第2期29卷 220-225页

作者： ZHANG Qian, ZHANG Boping, Li Haitao, and SHANG Pengpeng school of materials science and engineering, University of science and Technology Beijing, Beijing 100083, china school of materials science and engineering University of Science and Technology Beijing

Lead-free piezoelectric NaxK1-xNbO3（x = 0.3-0.8）（NKN） ceramics were fabricated by normal sintering at 1060°C for 2 *** and electrical properties of the ceramics were investigated with a special emphasis on the influence of Na *** grain size of the produced dense ceramic was decreased by increasing Na content.A discontinuous change in the space distance was found at the composition close to Na0.7K0.3NbO3 ceramic, which indicates the presence of a transitional composition between two different orthorhombic phases, which is similar to the behavior of morphotropic phase boundary（MPB） in NaxK1-xNbO3 *** MPB-like behavior contributes to the enhanced piezoelectric coefficient d33 of 122 pC/N, planar-mode electromechanical coupling coefficient kP of 28.6%, and dielectric constant εr of 703, respectively for the Na0.7K0.3NbO3 *** temperature TC and the transitional temperature TO-T from orthorhombic to tetragonal phase are observed at around 420°C and 200°C, respectively.

关键词： lead-free piezoelectric ceramics NKN sintering morphotropic phase boundary(MPB)

Effect of non-cyanide zincation process parameters on the microstructure of the zincation layer on A356 alloys

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2007年第S1期26卷 313-317页

作者： ZHU Zhaojun1),and HUANG Xiaomei2)1) school of materials science and engineering,Harbin Institute of Techmology,Harbin 150001,china 2) College of materials science and Chemical engineering,Harbin engineering University,Harbin 150001,china Harbin Inst Technol Sch Mat Sci & Engn Harbin 150001 Peoples R China Harbin Engn Univ Coll Mat Sci & Chem Engn Harbin 150001 Peoples R China

The effects of non-cyanide zincation process parameters on the microstructure of the zincation layer on A356 alloy were investigated by scanning electronic *** the increasing of zincation time,the zinc grain size and the number density increase gradually,and the zinc grains adhere each *** zinc grain obtained in the double-dipping process is finer,compacter and more homogeneous than that obtained in the single-dipping *** the increasing of the zincation temperature,the morphology of zinc grains changes from spherical shape to flake-like ***,higher zincation temperature results in the flaking off of the zincation layer from the *** optimized zincation temperature is 20-30 ℃.The quality of the zincation layer obtained in a low concentration,non-cyanide and multi-element zincation solutions is much better than these obtained in conventional high concentration zincation solution,dilute zincation solutions or a dilute zincation solution containing *** addition,the matrix alloy and the pre-treatment also have significant influence on the morphology of the zincation layer.

关键词： non-cyanide zincation solution zincation time zincation temperature morphology

Early Age Compressive Strength of Pastes by Electrical Resistivity Method and Maturity Method

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(materials science) 2011年第5期26卷 983-989页

作者：肖莲珍 school of materials science and engineering Wuhan Institute of Technology

The compressive strength development of Portland cement pastes was investigated by the electrical resistivity method and the maturity *** experiments were carried out on the cement pastes with different water-cement ratios at different curing *** results show that the application of the maturity method has limitation to obtain the *** is found that both of the compressive strength and the electrical resistivity follow hyperbolic trend for all the *** hyperbolic equation of each mix is obtained to estimate the ultimate resistivity value which can probably be *** relationship between electrical resistivity and compressive strength of the cement pastes is established based on the test results and interpreted by the empirical Archie equation and a strength-porosity *** relationship between the electrical resistivity after temperature correction and the compressive strength was linear and independent of curing temperature and water-cement ratio.

关键词： electrical resistivity cement hydration compressive strength maturity method

Blank design optimization for stepped-section profile ring rolling

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2010年第6期53卷 1612-1619页

作者： QIAN DongSheng & HUA Lin school of materials science and engineering,Wuhan University of Technology,Wuhan 430070,china 1. school of materials science and engineering Wuhan University of Technology Wuhan 430070 China

A stepped-section ring consists of two rectangular section rings,a big ring and a small ring,joined *** kind of ring is difficult to process by the ring rolling technique because of its complex cross-sectional *** a reasonable blank design is *** this paper,four blank designs,one is a rectangular cross-section and the other three are stepped-sections with different step volumes,are proposed and compared with each other using theoretical analysis,FE simulation and *** is shown that three of the designs can lead to volume flow from small ring into big ring during rolling,which is disadvantageous for shape formation and dimensional precision;however,the other design may result in good ring shape and high dimensional ***,the optimal blank design is determined to be the one in which the volumes of the big and small rings of the initial blank are equal to those of the final rings,respectively.

关键词： ring rolling stepped-section ring optimization design FE simulation

Melt-spun Al_(70-X)Si_(30)Mn_X (X=0,3,5,7,10) anode in lithium-ion batteries

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2009年第8期52卷 2288-2294页

作者： SUN ZhanBo1, LI XuePeng1, WANG XiaoDong1, HU Qing1, ZHAO MingShu1, ZHU YaoMin2, LI Yan2 & SONG XiaoPing1 1 school of science, State Key Laboratory for Mechanical Behavior of materials, Xi’an Jiaotong University, Xi’an 710049, china 2 school of materials science and engineering, Henan University of science and Technology, Luoyang 471003, china 1. school of science State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong University Xi’an 710049 China 2. school of materials science and engineering Henan University of Science and Technology Luoyang 471003 China

Al70-XSi30MnX (X=0, 3, 5, 7, 10, mol%) ribbons were prepared by melt spinning. A supersaturated solid solution of Si and Mn in fcc Al and some microstructures consisting of nano grains were obtained. Some alloys with nano-sized grains exhibited high discharge capacities and favorable cycle properties. The capacity of more than 400 mAh/g could be obtained in melt-spun Al67Si30Mn3 alloy after 20 cycles and more than 300 mAh/g after 40 cycles. Li/Si and Li/Al compounds in the anodes of pure Al and pure Si were not detected in Al-Si-Mn alloys inserted by Li. It is considered that the formation of the supersaturated solid solution and refinement of microstructures have prevented the alloys from the forming the compounds with superfluous Li. As a result, the electrochemical properties have been improved.

关键词： Al-Si-Mn alloy melt spinning microstructure electrochemical property

Phase transition in the Zr_(60)Al_(15)Ni_(25) bulk metallic glass subjected to rolling at room temperature

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2006年第6期49卷 655-662页

作者： YAN Zhijie1, 2, LI Jinfu1, ZHOU Yaohe1 & WU Yanqing3 1. State Key Laboratory of Metal Matrix Composites, school of materials science and engineering, Shanghai Jiao Tong University, Shanghai 200030, china 2. school of materials science and engineering, Taiyuan University of science and Technology, Taiyuan 030024, china 3. school of Environmental science and engineering, Shanghai Jiao Tong University, Shanghai 200030, china State Key Laboratory of Metal Matrix Composites School of Materials Science engineering Shanghai Jiao Tong University Shanghai 200030 China school of materials science engineering Taiyuan University of Science Technology Taiyuan 030024 China school of Environmental science engineering Shanghai Jiao Tong University Shanghai 200030 China

The microstructure evolution of the Zr60Al15Ni25 metallic glass during rolling at room temperature is investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC); high-resolution transmission electron microscopy (HREM). The results show that the values of full width at half maximum (FWHM) of the XRD patterns; exothermic enthalpy ΔH of DSC plots do not monotonically change with the variation of deformation degrees . As is not large than 20%, the values of FWHM; ΔH are lower than that of the as-cast state. When reaches 30%, the values of FWHM; ΔH become larger than that of the as-cast state, while their values begin to decrease again as reaches about 85%. These results indicate that the reversible transitions between ordered; disordered atomic configurations occur during rolling, which is further verified by the HREM images. The reversible phase transition can be explained by the competition between the diffusion controlled reordering; shear-induced disordering during rolling.

关键词： metallic glasses, plastic deformation, phase transformations, shear bands.

Three-Dimensional and Cross-sectional Characteristics of Normal Grain Growth Based on Monte Carlo Simulation

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and materials 1998年第3期12卷 129-133,139页

作者： Xiaoyan Song Guoquan Liu(Material science and engineering school, University of science and Technology Beijing, Beijing 100083, china)(Department of materials science and engineering, Hebei University of Technology, Tianjin 300130, china) Material science and engineering school University of Science and Technology Beijing Beijing 100083 China Departments of materials science and engineering Hebei University of Technology Tianjin 300130 China

An appropriate Monte Carlo method was developed to simulate the three-dimensional normal grain growth more completely. Comparative investigation on the three-dimensional and the cross-sectional characteristics of normal grain growth was done. It was found that the time exponent of grain growth determined from cross-section exhibits the same rule of increasing slowly with time and approaching the theoretical value n = 0.5 of steadygrain growth as the three-dimensional (3-D) system. From change of the number of grains per unit area with timemeasured in cross-section, the state of 3-D normal grain growth may be predicted. The gtain size distribution incross-section is different from that in 3-D system and can not express the evolution characteristic of the 3-D distribution. Furthermore, there exists statistical connection between the topological parameters in cross-section and thosein three-dimensions.

关键词： Monte Carlo simulation normal grain growth three-dimension cross-section characteristics