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Dislocation evolution with rheological forming of metal

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中国有色金属学会会刊：英文版 1999年第3期9卷 623-628页

作者： Luo Yingshe(罗迎社) Guo Xiaogang(郭小刚) Mei Yafu(梅亚夫) Hu Yungui(胡云贵) res inst Fundamental mech & Mat engn Xiangtan 411105 Peoples R China

It is known that some internal defects exist in metal materials. Preliminary attempt to relate dislocation evolution with metal rheological forming was done. By the attempt, it is learned that the evolution of dislocation density ρ(x, y, t) is essentially the change of n independent internal variables q α(α=1, 2, …, n) with material. The preliminary research in theory and experiments showed that dislocations piling up could be avoided. One can improve the internal microstructure and mechanical properties of products by rheological forming method.

关键词： dislocation metal rheological forming

Modeling and Simulation of Iron-Carbon Phase Transformation During Tempering of Steel

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稀有金属材料与工程 2012年第S1期41卷 6-12页

作者： Dong-ying Ju1,Xiao-hu Deng 2 1Department of mechanical Engineering,Saitama institute of Technology,Saitama,Japan 2 Advanced Science research Laboratory,Saitama institute of Technology,Saitama,Japan Saitama inst Technol Dept Mech Engn Saitama Japan Saitama inst Technol Adv Sci Res Lab Saitama Japan

Tempering is final process used in heat treatment of steel *** is important to improve the toughness and ductility of the quenched steel without a great loss of the hardness and ***,the traditional tempering process is hard to satisfy requirements of combination mechanical properties with low cost.A quantitative model is developed to simulate the micro-structural evolution during tempering process of carbon steel by modifying the previous Ju and Inoue's *** model takes into account tempering parameters,carbon content and morphology for iron-carbon *** of carbon atoms,precipitation of transition carbides(ε-carbide),decomposition of retained austenite and precipitation of cementite can be predicted *** precipitation of carbides is modeled by considering the competitive precipitations ofε-carbide and *** kinetics of decomposition of retained austenite into ferrite and cementite is depicted by the modified Avrami *** validate the model,it is applied to simulate the tempering process of the as-quenched plain carbon *** volume fractions of iron-carbon phase are calculated at different tempering temperature and *** is indicated that tempering time has greater effect on the volume fraction of carbides at high temperature *** calculated results are reasonable consistent with the theoretical descriptions.

关键词： tempering phase transformation kinetics transition carbide cementite

EFFECTS OF MICROSTRUCTURE ON THE MACROSCOPIC ELASTO-PLASTIC PROPERTIES OF METAL MATRIX COMPOSITES

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Acta mechanica Solida Sinica 1996年第1期9卷 52-58页

作者： Chen, HR Su, XF Tang, LM DALIAN UNIV TECHNOL RES INST ENGN MECHDALIAN 116023PEOPLES R CHINA

The generalized self-consistent finite-element iterative averaging method was adopted to analyze the elasto-plastic tensile properties of SiC whiskers reinforced aluminum matrix composites. The effects of varying fiber's aspect ratio and volume fraction on the macroscopic elasto-plastic deformation of the composites were studied. By the analysis of microscopic stress fields, the relation between the propagation of the elasto-plastic region in the matrix and the macroscopic elasto-plastic deformation of composites was discussed. It was found that the propagation of the plastic region in the matrix between the fiber's ends would affect prominently the elasto-plastic tensile behaviour of the composites. It was shown that the characterization of the stress-strain response in terms of the 0.2% offset yield strength is incomplete.

关键词： metal-matrix composites microstructure macroscopic elasto-plastic behaviour microscopic plastic region generalized self-consistent finite-element iterative averaging method

Colloid-facilitated effects on migration of radionuclides in fractured rock with a kinetic solubility-limited dissolution model

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Nuclear Science and Techniques 2010年第6期21卷 339-346页

作者： Jen, Chun-ping Tien, Neng-chuan Chung Cheng Univ Dept Mech Engn Taipei 62102 Taiwan Ind Technol res inst Energy & Environm Res Labs Hsinchu 31040 Taiwan

Nuclides can move with groundwater either as solutes or colloids,where the latter mechanism generally results in much shorter traveling time as the nuclides interact strongly with solid phases,such as *** the performance assessment,it is therefore essential to assess the relative importance of these two transport mechanisms for different *** relative importance of colloids depends on the nature and concentration of the colloids in ***(Pu),neptunium(Np),uranium(U) and americium(Am) are four nuclides of concern for the long-term emplacement of nuclear wastes at potential repository *** four actinides have a high potential for migrating if attached to iron oxide,clay or silica colloids in the *** sorption of the actinides by colloids in the groundwater may facilitate the transport of these nuclides along potential flow *** solubility-limited dissolution model can be used to assess the safety of the release of nuclear waste in geological disposal ***,it has been assumed that the solubility of the waste form is *** a nuclide reaches its solubility limit at an inner location near the waste form,it is unlikely that the same nuclide will reach its solubility limit at an outer location unless this nuclide has a parent *** is unlikely that the daughter nuclides will exceed their solubility limit due to decay of their parent *** present study investigates the effect of colloids on the transport of solubility-limited nuclides under the kinetic solubility-limited dissolution(KSLD) boundary condition in fractured *** release rate of the nuclides is proportional to the difference between the saturation concentration and the inlet aqueous concentration of the *** presence of colloids decreases the aqueous concentration of nuclides and,thus,increases the release flux of nuclides from the waste form.

关键词：核素迁移胶体浓度溶解度动力学裂隙岩体模型地下水溶质锕系元素

INTERVAL PARAMETER PERTURBATION METHOD FOR EVALUATING THE BOUNDS ON NATURAL FREQUENCIES OF STRUCTUres WITH INTERVAL PARAMETERS

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Acta mechanica Solida Sinica 1998年第1期11卷 56-62页

作者： Qiu Zhiping Gu Yuanxian Beijing Univ Aeronaut & Astronaut Inst Solid Mech Beijing 100083 Peoples R China Dalian Univ Technol Res Inst Engn Mech Dalian 116023 Peoples R China

For structural parameters with uncertainties, interval mathematicscan , in the case where the probabilistic distribution density ofuncertain variables is unavailable, deal with the influ- ence ofuncertainties in structural parameters on the response of *** order to evaluate the re- gion containing natural frequencies ofstructures with interval parameters, the interval parameter per-turbation method is presented in this paper. The advantage of thepresent method is its computational efficiency in evaluating theregion containing natural frequencies. A numerical example is used toil- lustrate the efficiency of the method proposed.

关键词： region containing natural freuqency interval mathematics intervalparameter perturbation method

Microstructural Characteristics and Stability in a RapidlySolidified Al-Fe-Nb-Si Alloy

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Journal of Materials Science & Technology 1997年第6期13卷 515-517页

作者： Guan, SK Shen, NF Gong, YL Hu, HQ zhengzhou Univ Technol Dept Mat Sci & Engn Zhengzhou 450002 Peoples R China Cent China Petr & Nat Gas Dev Corp Henan Province Zhengzhou 450002 Peoples R China Univ Sci & Technol Beijing Inst Mat Beijing 100083 Peoples R China

The microstructure and stability in a rapidly solidified Al-Fe-Nb-Si alloy were studied by using transmission electron microscopy (TEM) with energy dispersive X-ray spectrometry (EDXS) and X-ray diffraction technique. It is shown that the addition of Nb to Al-Fe-Si alloy may increase undercooling of melt, and form the featureless zone structure, the size of the intercellular phases and the distance between intercellulars of Al-Fe-Nb-Si alloy are two times smaller than that of AI-Fe-V-Si alloy under the same conditions. Further, the microstructure of the featureless zone has the better thermal stability after annealing at 623 K for 24 h.

关键词： Aluminum alloys

Ultrasonic Frequency Fast-Convert Pulse Plasma Spraying Power Supply Topology

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稀有金属材料与工程 2011年第S4期40卷 297-301页

作者： Zhang Wei1,Qi Bojin1,Xu Haiying21School of mechanical Engineering and Automation,BeiHang University,Beijing 100191,China2Beijing Aeronautical Manufacturing Technology research institute,Beijing 100024,China BeiHang Univ Sch Mech Engn & Automat Beijing 1000191 Peoples R China Beijing Aeronaut Mfg Technol res inst Beijing 100024 Peoples R China

Considering the high DC current and high pulse frequency characteristic of ultrasonic frequency fast-convert pulse plasma spraying process,a special power supply topology was proposed,which was composed of the mutual independent base current circuit and peak current *** current circuit was consisted of four parallel direct current power supplies,which was not only to meet the requirements of high power output,but also improved the reliability of power *** on the Boost circuit topology,a peak current circuit was designed,which could reduce effectively the output inductance influence and output ultrasonic frequency pulse high current with fast-convert rising and falling *** on the above techniques,the Ultrasonic frequency fast-convert pulse plasma spraying power supply was *** can output 5-1000A base current,0-250A peak current,and the pulse current frequency band is 20-100kHz,10%～80% duty ratio and pulse current change rate over 50A/μs.

关键词： Ultrasonic frequency pulse Fast-convert Plasma spraying

Combined adjustment project of national astronomical geodetic networks and 2000' national GPS control network

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Progress in Natural Science:Materials International 2005年第5期15卷 435-441页

作者： YANG Yuanxi1*, ZHA Ming2, SONG Lijie3, WEI Ziqing1, WANG Zhouping2, OUYANG Guichong2, XU Bilin2, WU Xiaoping3 and WANG Junqin4(1. Xi'an research institute of Surveying and Mapping, Xi'an 710054, China 2. Xi'an Informational and Technical Center of Surveying and Mapping, Xi'an 710054, China 3. zhengzhou institute of Surveying and Mapping, zhengzhou 450052, China 4. The First Surveying Team of Tianjin, Tianjin 300140, China) Xi'an res. inst. of Surveying and Mapping Xi'an 710054 China Xi'an Info. and Technical Ctr. of Surveying and Mapping Xi'an 710054 China zhengzhou inst. of Surveying and Mapping Zhengzhou 450052 China First Surveying Team of Tianjin Tianjin 300140 China

The combined adjustment project of the nationwide astronomical geodetic networks and 2000' national GPS control network involve 48519 terrestrial observational stations and 2666 GPS observational stations. In the terrestrial network, 25107 stations are height fixed and 23412 stations are in three dimensions. 440793 terrestrial observations and 183668 unknowns are involved in the adjustment. The three-dimensional observational models for the adjustment have been established. The crustal deformation influences and corrections are researched. Fast methods of solving partitioned adjustment for super large-scale geodetic network have been studied. The standard deviations of three-dimensional coordinates for all stations are evaluated. As a result of the combined adjustment, a unified national geodetic network with nearly 50000 stations is established, the high accurate three-dimensional geocentric coordinates are obtained. The standard deviation for geoid is averagely 0.2 m, for vertical deflection is about 1.5″, for the horizontal position is about 0.12 m, for the geodetic height is about 0.14 m, and for the three-dimensional position is averagely 0.3 m.

关键词： astronomical geodetic network GPS network combined adjustment datum geocentric coordinates.

Age-hardening of surface aged hardening alloy

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中国有色金属学会会刊：英文版 2000年第6期10卷 788-790页

作者：李忠厚刘小萍赵金香徐重 Taiyuan Univ Technol Res Inst Surface Engn Taiyuan 030024 Peoples R China

Steel T8 treated by plasma surface decarburizing was alloyed by the Xu Tec process with Co,W and Mo. An alloyed layer of Fe Co W Mo with low carbon content was formed on the surface of the high carbon steel, thus an advanced gradient composite was produced. The specimens then were treated by the solution and aging treatments. The characteristics of age hardening of the alloying layer were studied. The hardness of the surface layer increases from HV200 to HV1 200 after the solution treatment at 1 190 ℃ and aging at 400 ℃ for 30 min. The results show that the surface aged high speed steel possesses not only high surface hardness, but also enough bulk strength. [

关键词： high carbon steel plasma decarburizing age hardening surface aged hardening alloy(