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Analysis for twinning and slip in face-centered cubic crystals under axisymmetric co-deformation

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science {1.(Technological sciences) 2006年第5期49卷 521-536页

作者： CHEN Zhiyong1,2, CAI Hongnian1, zhang Xinming2, WANG Fuchi1 & TAN Chengwen1,3 1. {1. of material science and engineering, beijing Institute of technology, beijing 100081, china 2. {1. of material science and engineering, Central South {1.}, Changsha 410083, china 3. {1. of material science and engineering, beijing {1.} of Aeronautics and Astronautics, beijing 1.0083. china school of {1. {2. and engineering Beijing Institute of Technology Beijing China school of {1. {2. and engineering Central South University Changsha China school of {1. {2. and engineering Beijing University of Aeronautics and Astronautics Beijing China

The maximum work principle of Bishop-Hill was developed to analyze the axisymmetric co-deformation in face-centered cubic crystals (f.c.c.) for twinning on {1.1. 1.2.and slip on {1.1. 1.0 systems. The influence of ξ , the ratio of critical re- solved shear stress for twinning to slip, on the yield stress states and corresponding active slip or/and twinning systems for orientations in the standard stereographic triangle of cubic crystal was investigated systematically. The Taylor factors and the anisotropy of yield strength for three important orientations [1.0], [1.0] and [1.1. in orientation space were analyzed. It is found that the yield strength asymmetry for the case of axisymmetric de- formation of tension and compression can be explained based on the microscopic theory of crystal plasticity. The concept of orientation factor for twinning ability was proposed and the deformation mechanism map in the orientation space was established for the case of axisymmetric deformation. The deformation texture formation and development of f.c.c. crystals with low stacking fault energy for axisymmetric tension can be explained qualita- tively on the basis of analyzed results.

关键词： twinning slip face-centered cubic crystals axisymmetric co-deformation Bishop-Hill maximum work principle yield strength anisotropy

Reaction Sintering of Fe-Al Powder Mechanically Activated

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International Journal of Minerals,Metallurgy and materials 1998年第4期12卷 233-236页

作者： Chengchang jia Xiaosen Lu Jun Zhao Zizhang xie({2. science and engineering school, university of science and technology beijing, beijing 1.0083. china) (beijing Hard Metal Factory, beijing 100055, china) material {1. and {2. school University of Science and Technology Beijing Beijing 100083 China beijing Hard Metal Factory Beijing 100055 China

The mixture of Fe and Al powder was mechanically activated and sintered to study a non-melting methodof producing the intermetallics Fe3Al. High-energy ball milling was used as an activation method, X-ray diffractionand SEM were chosen to analyze the materials variation before and after activation and sintering, and hot press ofFe-Al powder was inveshgated to compare mechanical activation with sintering. The results show that combiningmechanical activation with reaction sintering can complete the transformation from pure Fe and Al powder to intermetallics. It is difficult to do the transformation by either mechanical activation or hot press.

关键词： intermetallic compound sintering metal powder mechanical activation

Effect of the silicon powder content on the properties of Al_2._3-SiC-Me composites

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science {1.(Technological sciences) 2009年第1期52卷 193-197页

作者： zhang ZhiHui1, RUAN GuoZhi1 & CHEN YunBo1,2.1 {1. of {2. science and engineering, Shandong university of science and technology, Qingdao 2.6510, china 2.Institute of {2. engineering, china Academy of Machinery science and technology,{1.} school of {1. {2. and engineering Shandong University of Science and Technology Qingdao China Institute of material {1. China Academy of Machinery Science and Technology Beijing China

By means of transient plastic phase process, the Al2.3-SiC-Me composites were produced throungh adding metal aluminium and silicon-powder to Al2.3-SiC materials. Under the condition of the same content of silicon and aluminium mixed-powder, the effect of silicon powder addition on properties of Al2.3-SiC-Me composites was studied by means of XRD and EPMA analyses in the temperature range of 300℃―1.00℃. The results indicated that the content of metal phase in the sample at 1.00℃ increases with increasing silicon powder content. At the same time, when the temperature is lower than 1.00℃, the strength of samples gradually increases with increasing temperature. However when the temperature is higher than 1.00℃, the strength of samples gradually decreases with increasing temperature, and this change is very small. The results also indicated that at the same sintering temperature, the sample with 6% silicon powder has the maximum strength.

关键词： composites strength ceramic

Surface Metallurgy of Nickle Base Superalloy

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International Journal of Minerals,Metallurgy and materials 1999年第1期13卷 47-49页

作者： Xu zhang Zhongmin Yang Jianxin Dong Xishan xie Yuan Gao Zhong Xu ({2. science and engineering school, university of science and technology beijing, beijing 1.0083. china)(Institute of Surface engineering, Taiyuan university of technology, Taiyua material {1. and {2. school University of Science and Technology Beijing Beijing 100083 China Institute of Surface engineering Taiyuan University of Technology Taiyuan 030024 China

The Double Glow Plasma Surface Alloying Technique, the Xu-Tee Process, is a new method to produce high quality alloying layer on the surface of less expensive materials. By using thes technique, the surface alloying layer similar to superalloy Inconel 62. has been obtained on the surface of three kinds of melallic materials (low carbon steel, industrial pure iron, stainless steel Cr{2.Ni9). The results of the composition and microstructure analyzed by Scanning Electron Microscopy (SEM) and X-Ray Uffrachon (XRD) show that the alloying layer consistS of y matrix and several precipitates (Laves intermetallic phase and carbide etc.). The electrochemical corrosion results show that the surface alloying layer formed on the surface of stainless steel and industrial pure iron have better corrosion resistance than that of nickel base alloy inconel 62. and stainless steel Cr{2.Ni9 in 3.5%NaCl solution. The exper iments indicate that it is an effective way to obtain the gradient surface alloying layer on the surfaces of steels by using Double Glow Plasma Surface Alloying Technique.

关键词： double glow nickel base alloy plasma surface alloying

Modified HDDR Process for Producing Anisotropic NdFeB Powders

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Journal of university of science and technology beijing 2001年第2期8卷 111-114页

作者： Xubo Liu, Yue Ming, Yaofu Xiao, Qi Zeng, Zhengyi zhang, Run Wang ({1. {2. and engineering school, university of science and technology beijing, beijing 1.0083. china) (beijing Institute of Aeronautical {1.s, beijing 100095, {1.}) material Sci. and {1. {2. University of Science and Technology Beijing 100083 China

The effect of HDDR (hydrogenation-decomposition-desorption-recombination process) treating conditions on magnetic anisotropy of Nd1.FebalCo1.B7Ga1.r0.1.powders has been studied. It is found that increasing recombination temperature is effective for magnetic anisotropy formation, but at the cost of reducing the coercive force. The microstructure analysis (TEM) indicates that the NdFeB recombination nucleation takes place markedly during the transition range from decomposition stage to recombination stage, in which both temperature and H-2.pressure change sharply. In order to create a more stable treatment condition for recombination nucleation, a modified HDDR process is established in which the conventional continuous transition range is divided into several stages. The experimental results have proved that such a process can effectively enhance the remanence of the magnet powders with high certainty, while only cause a little reduction in coercivity.

关键词： HDDR anisotropy NdFeB

INFLUENCE OF ASSOCIATED AND SEPARATE PRECIPITATION OF γ″ AND γ′ ON STRUCTURE STABILITY IN INCONEL71. AND MODIFIED ALLOYS

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Acta Metallurgica Sinica(English Letters) 1993年第6期6卷 410-414页

作者： DONG jianxin xie Xishan zhang Shouhua{1.,beijing,china doctorate student,Department of materials science and engineering,university of science and technology beijing,beijing {1.}china Univ of science and {1. Beijing Beijing China

The precipitation behavior in Inconel 71. and modified alloys has been studied by means of *** structure of associated precipitation and compact morphology of γ″+γ′ were ob- tained by modifying the contents of Al,Ti and *** results show that the com- pact morphology of γ″+γ′ has the best structure stability at higher *** of the transformation γ″→δ in alloy 71. the dissolution of strengthening phases in modified alloy leads {2. degradation.

关键词： superalloy structure stability associated precipitation compact morphology Inconel 71.

Chemical Extraction Preparation of Delithiated Cathode materials of Li-ion Battery

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Journal of Wuhan university of {1.({2.s science) 2009年第6期24卷 863-866页

作者：闫时建 school of {1.s {2. and engineering Taiyuan University of Science and Technology

A method of conventional chemical reaction to prepare delithiated cathode materials of Li-ion battery was introduced. The cathode material of Li-ion battery was mixed with oxidizing agent Na2.2.8 in water solution, and the solution was stirred continuously to make the chemical reaction proceed sufficiently, then the reaction product was filtered and finally the insoluble delithiated cathode material was obtained. A series of tests were conducted to verify the composition, crystal structure and electrochemical property of the delithiated cathode materials were all desirable. This method overcomes the shortcomings of battery charging preparation and chemical extraction preparation employing other oxidizing agents.

关键词： chemical extraction delithiated cathode material Li-ion battery

Effects of binders on the performance of electric double-layer capacitors of carbon nanotube electrodes

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Progress in Natural science:{1.s International 2005年第5期15卷 453-457页

作者： LI Chensha1.*, WANG Dazhi1. {2. Baoyou2. WANG Xiaofeng1. CAO Maosheng3 and LIANG Ji1.1. Department of Mechanical {1., Tsinghua university, beijing 1.0084, china 2. Center for Analysis and Measurement, Harbin Institute of technology, Harbin 1.0001. china 3. school of material science and {1., Tsinghua university, beijing 1.0084, china) Dept. of Mech. Eng. Tsinghua Univ. Beijing 100084 China Ctr. for Analysis and Meas. Harbin Inst. of Technol. Harbin 150001 China Sch. of Mat. Sci. and Eng. Tsinghua Univ. Beijing 100084 China

Polarizable electrodes of electric double layer capacitor (EDLCs) were made from carbon nanotubes. Effects of different binders, which are phenolic resin (PF) and polytetrafluoroethylene (PTFE), on the properties of polarizable electrodes are studied. Results indicate that the microstructure, pore size distribution and specific capacitance of the electrodes with PTFE binder are superior to those electrodes with PF binder after carbonization. The suitable binder (PTFE) for carbon nanotubes electrodes is proposed.

关键词： carbon nanotubes electric double-layer capacitors phenolic resin polytetrafluoroethylene.

Effect of bond length and radius on superconducting transition temperature for FeAs-based superconductors

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science {1.(Physics,Mechanics & Astronomy) 2010年第1期53卷 59-63页

作者： CHEN Ning 1 , LIU Yang 1 , JIA YaKui 1 , QU ShaoPeng 1 , zhang WanJie 1 & LI Yang 2.1 {1. of {2. science and engineering, university of science and technology beijing, beijing 1.0083. china 2.Department of engineering science and {2.s, {1.} of Puerto Rico at Mayaguez, Mayaguez PR 00681-9044, USA school of {1. {2. and engineering University of Science and Technology Beijing Beijing China Department of engineering {1. and {2.s University of Puerto Rico at Mayaguez Mayaguez USA

By comparing the data of lattice parameters of more than 50 new FeAs-based high temperature superconductors in two syetems, the effect of bondlength on superconducting transition temperature (T C ) was found that, for both FeAs superconductor systems with similar ionic radii of cation A, the bond length L As-A between Arsenic atom and its nearest neighbor cation at the A site is in an inverse proportion to T C , i.e. the larger the bond length L As-A , the lower the T C . In addition, we also found a noticeable effect of ionic radius on T C , in which deviation from the tendency line of bond length vs. T C decreases with the increasing ionic radius. Both bond length-T C and ionic radii-T C relations indicate that the interaction of cation A and As ion have significant effect on superconductivity. The analysis on the electronic structure indicates that there exists the proximity of the secondary-outer p-orbit of the cation A and the 4s orbit of the As ion, both in energy space and in real space. Some high frequency individual vibrating modes would be established through exchange coupling on their inner orbits. It is worth of mention that the superconducting condensation is influenced by the interaction between the cation A and the As atoms.

关键词： lattice constant FeAs-based superconductor superconducting transition temperature