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Numerical Study of Scale Effects of Ultra-Thin Nickel Beams

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Journal of Rare Earths 2004年第Z2期22卷 170-173页

作者： Li Lei Xie Shuisheng Yang Haoqiang Huang Guojie general research institute for non-ferrous metals Beijing 100088China General Research Institute for Non-Ferrous MetalsBeijing 100088China General Research Institute for Non-Ferrous MetalsBeijing 100088China General Research Institute for Non-Ferrous MetalsBeijing 100088China

Recent experiments have shown that metallic materials display significant size effects when the characteristic length scale of non-uniform plastic deformation is close to a micron. Couple stress plasticity has been developed to explain such phenomena by Fleck and Hutchinson. The mechanical behaviors of ultra-thin nickel beams in different boundary conditions were studied with the hybrid element developed for couple stress plasticity before. Strong scale effects are found when the beam's thickness is close to the material characteristic length scale. Such phenomena will disappear if the beam' s thickness is greatly larger than the material characteristic length scale. The scale effect is the beams inherent property and it does not change with the change of support conditions.

关键词： scale effect MEMS couple stress plasticity hybrid element

Effect of homogenization on microstructure and properties of WE91 alloys

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Journal of Rare Earths 2013年第8期31卷 830-836页

作者：马鸣龙张奎李永军李兴刚石国梁 State Key Laboratory for non-ferrous metals and Processes Beijing General Research Institute for Non-Ferrous Metals

The microstructure and properties of the Mg-9Y-1MM-0.6Zr alloy were studied by scanning electron microscopy, optical microscopy, transmission electron microscopy, hardness and tensile testing. Homogenization was confirmed, and the solidification model was established. The as-cast alloy was mainly composed of ct-Mg and eutectic structures. The suitable homogenization pa- rameters were 535℃ for 18 h. Most of the eutectic structure dissolved in this process. Only the Mg4.26Y95.74 and Mg12 （MM） phases were remained in, and only a few microstructure occurred for prolonged time. The ultimate tensile strength of the alloy increased up to 232 MPa after homogenization, but the yield strength and the elongation were almost as same as the as-cast state. In the as-cast al- loys the cracks started in the eutectic structure, and then intergranular fracture occurred, but in the homogenate alloys residual phases became the source of the cracks and then tmnscrystalline fracture took place. The most important roles of homogenization were the decomposition of the eutectic structure, furthermore the intergranular fracture turned into a transcrystalline fracture, which was one of the main reasons to increase the strength of the alloys.

关键词： rare earth magnesium alloy homogenization microstructure mechanical property

Homogenization heat treatment of Mg-7.68Gd-4.88Y-1.32Nd-0.63Al-0.05Zr alloy

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Journal of Rare Earths 2014年第5期32卷 445-450页

作者：张国栋李兴刚马鸣龙李永军石国梁袁家伟张奎 State Key Laboratory for Fabrication and Processing of non-ferrous metals Beijing General Research Institute for Non-ferrous Metals

The microstructures and mechanical properties of the Mg-7.68Gd-4.88Y-1.32Nd-0.63A1-0.05Zr magnesium alloy were investigated both in the as-cast condition and after homogenization heat treatment from 535 to 555 ℃ in the time range 0-48 h by op- tical microscopy, scanning electron microscopy and hardness measurement. The as-cast alloy consisted of ct-Mg matrix, Mgs（Y0.5Gd0.5） phase which is a eutectic phase, strip of Al2（Y0.6Gd0.4） phase, little A13Zr and Mg（Y3Gd） phase. With the increasing of homogenization temperature and time, the Mgs（Y0.5Gd0.5） phase was completely dissolved into the matrix. The Al2（Y0.6Gd0.4） phase was almost not dissolved which impeded grain boundaries motion making the grain size almost not changed in the process of ho- mogenization. The optimum homogenization condition was 545 ℃/16 h. The tensile strength increased, yield strength decreased and the plasticity improved obviously after 545 ℃/16 h homogenization treatment.

关键词： Mg-Gd-Y-Nd-AI alloy homogenization second phase hardness rare earths

Comparison of measurements and simulation results in 300mm CZ silicon crystal growth

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Rare metals 2007年第6期26卷 607-610页

作者： GAO Yu TU Hailing ZHOU Qigang DAI Xiaolin XIAO Qinghua general research institute of non-ferrous metals Beijing 100088

A special thennat modeling tool, CrysVUn, which was developed by Crystal Growth Laboratory （CGL） of Fraunhofer institute of Integrated Systems and Devices Technology in Erlangen of Germany, was used for numerical analysis of growth interface situation. The heat transportation, argon flow and melt convection have been considered. Cauchy＇s first and second laws of motion have been the governing partial equations for stress calculation. The measurement results and simulation results were compared and the interface shape and thennat stress distribution during 300 mm Czochralski （CZ） silicon crystal growth with different growth rates were predicted.

关键词： silicon simulation interface growth rate

Annulus electromagnetic stirring for preparing semisolid A357 aluminum alloy slurry

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中国有色金属学会会刊：英文版 2009年第5期19卷 1104-1109页

作者：白月龙徐骏张志峰石力开 general research institute for non-ferrous metals

The effects of pouring temperature and annulus gap width on the microstructure of the semi-solid A357 aluminum alloy slurry prepared by annulus electromagnetic stirring(AEMS)technology were *** results show that low pouring temperature and narrow annulus gap are advantageous to obtaining the small spherical primaryα(Al)*** lower the pouring temperature is and the smaller the annulus gap width is,the more uniform,the smaller and the more spherical the microstructure is. The microstructures obtained by the ordinary electromagnetic stirring and AEMS were *** results indicate that the primaryα(Al)particles are globular,small and distribute homogeneously in the slurry obtained by *** in the slurry obtained by the ordinary electromagnetic stirring,the primaryα(Al)particles are small dendrites in the edge of the slurry and they are large and rosette-like or dendritic in the inner of the slurry.

关键词：电磁搅拌制备温度金浆料半固态铝环形浇注温度水泥浆

Microstructure evolution of 7050 aluminum alloy during hot deformation

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Transactions of nonferrous metals Society of China 2010年第2期20卷 189-194页

作者：李俊鹏沈健闫晓东毛柏平闫亮明 general research institute for non-ferrous metals

Hot compression of 7050 aluminum alloy was performed on Gleeble 1500D thermo-mechanical simulator at 350 ℃ and 450 ℃ with a constant strain rate of 0.1 s-1 to different nominal strains of 0.1, 0.3 and 0.7. Microstructures of 7050 alloy under various compression conditions were observed by TEM to investigate the microstructure evolution process of the alloy deformed at various temperatures. The microstructure evolves from dislocation tangles to cell structure and subgrain structure when being deformed at 350 ℃, of which dynamic recovery is the softening mechanism. However, continuous dynamic recrystallization (DRX) occurs during hot deformation at 450 ℃, in which the main nucleation mechanisms of DRX are subgrain growth and subgrain coalescence rather than particle-simulated nucleation (PSN).

关键词： microstructure evolution dynamic recovery dynamic recrystallization hot deformation 7050 alloy

Preparation of semi-solid slurry at power frequency by annulus electromagnetic stirring method

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中国有色金属学会会刊：英文版 2009年第S3期19卷 531-536页

作者：白月龙徐骏张志峰石力开 general research institute for non ferrous metals

The effect of stirring frequency on the semi-solid A357 aluminum alloy microstructure was investigated by annulus electromagnetic stirring(AEMS) method. The microstructures obtained by AEMS method and ordinary electromagnetic stirring(EMS)method were compared and analyzed. The results show that the primary α(Al) particles become more spherical and fine, and disperse uniformly in a liquid matrix with increasing stirring frequency, and higher stirring frequency is advantageous to obtain the fine spherical semi-solid microstructure by AEMS. Compared with the microstructures obtained at stirring frequency of 50 Hz in EMS, the fine spherical and uniformly distributed semi-solid microstructures can be still obtained at stirring frequency of 50 Hz in AEMS, so stirring frequency of 50 Hz is recommended in AEMS to save investment cost on frequency-conversion facilities.

关键词： A357 aluminum alloy semi-solid electromagnetic stirring slurry preparation

Transmission　Electron　Microscope　Study　of　YBCO/CeO_2/Si Superconducting Multilayer Films

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Journal of Rare Earths 1997年第2期15卷 43-49页

作者：李灏刘安生古宏伟陈岚锋 general research institute for non-ferrous metals Beijing 100088 China

YBa 2Cu 3O 7- x (YBCO) thin film has been deposited on Si substrate with CeO 2 buffer layer and shows a relatively high critical transport current density J c exceeding 1 0×10 6 A/cm 2 at 77 K in zero magnetic field. The orientation relationship of the multilayer films has been studied. The (001) plane of YBCO film is parallel to the (100) plane of Si substrate. The CeO 2 buffer layer consists of many small(40 nm×100 nm) column like crystal grains which have different orientations. Although the theoretical lattice mismatch between CeO 2 and Si is very small(about 0 4%), CeO 2 can not grow epitaxially on Si substrate yet. Because of habit growth, YBCO grows with c orientation preference on scattered oriented CeO 2. A thin amorphous layer between Si and CeO 2 has been observed. There exist several Y 2BaCuO 5(211 phase) grains in the interface of CeO 2 and YBCO. A 123 and 248 phase miscellany region and several Y 2O 3 inclusions have been observed.

关键词： Rare earths Microstructure YBCO Film Multilayer

Evolution of Hydrogen Storage Alloys Prepared by Special Methods

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Journal of Rare Earths 2004年第Z1期22卷 222-227页

作者： Guo Hong Zhang Ximin Jing Hai Li Chengdong Xu Jun National Engineering and Technology research Center for non-ferrous metals Composites General Research Institute for Non-Ferrous Metals Beijing 100088 China National Engineering and Technology Research Center for Non-Ferrous Metals Composites General Research Institute for Non-Ferrous Metals Beijing 100088 China National Engineering and Technology Research Center for Non-Ferrous Metals Composites General Research Institute for Non-Ferrous Metals Beijing 100088 China National Engineering and Technology Research Center for Non-Ferrous Metals Composites General Research Institute for Non-Ferrous Metals Beijing 100088 China National Engineering and Technology Research Center for Non-Ferrous Metals Composites General Research Institute for Non-Ferrous Metals Beijing 100088 China

Microstructure characteristics and electrochemical properties of hydrogen storage alloys prepared by gas atomization, melt spinning and strip casting respectively were *** advantages, disadvantages and research development of the above methods for preparing hydrogen storage alloys were *** strip casting is a new special means for preparing AB5 rare earth hydrogen storage alloys of high performance and low cost, and the study of the strip casting for preparing hydrogen storage alloys is presented specially.

关键词： hydrogen storage alloys gas atomization melt spinning strip casting rare earths