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Microstructure Characteristics and Apparent Viscosity of Hypereutectic Al-2.%Si Alloy Melt During Semi-solid State Stirring

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Journal of university of science and Technology {2. 2001年第2期8卷 126-128页

作者： Yanjun Li, Weimin Mao, Zisheng Zhen, Xueyou Zhong (material science and Engineering {2., university of science and Technology beijing, beijing 100083. china) Univ Sci & Technol beijing Mat Sci & Engn Sch Beijing 100083 Peoples R China

The microstructural evolution and apparent viscosity of hypereutectic Al-2.%Si alloy during semi-solid state shearing were studied with a Searte type viscometer. When the alloy melt was continuously stirred from 72. degreesC to eutectic temperature, the primary Si crystals were gradually changed from elongated platelets to near-spherical shapes. It was found that some nondendritic a-phase formed when the melt was stirred below 585 degreesC. The experiment showed that the semi-solid stirring had strong effect on inhibiting the anisotropic growth of Si crystals during solidification. The apparent viscosity of the alloy melt increased slowly with the decreasing of temperature before the formation of nondendritic alpha -phase, which caused the dramatic increase of apparent viscosity.

关键词： hypereutectic Al-Si alloy solidification structures apparent viscosity

Theory for Constructing Generalized Synchronization and Applications

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International Journal of Minerals,Metallurgy and materials 2000年第3期14卷 225-228页

作者： Xiaodan Zhang, Lequan Min (Applied science school, {2. of science and Technology beijing, beijing 100083. china) Applied science school University of Science and Technology Beijing Beijing 100083 China

The approaches for constructing directionally coupled generalized synchronization (GS) systems are presented, which are available for the driving system and the respond system that are in GS via a given diffeomorphi... 详细信息

关键词： Chaos generalized synchronization predictability

Adhesion of NiCu Films DC Biased Plasma-Sputter-Deposited on MgO (001)

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International Journal of Minerals,Metallurgy and materials 2000年第3期14卷 218-221页

作者： Hong Qiu, Mituru Hashimoto ( beijing Keda-Tianyu Microelectronic material Technology Development Corporation,{2. Applied science school, university of science and Technology beijing,{2. Department of Applied Phys beijing Keda-Tianyu Microelectronic material Technology Development Corporation Beijing 100083 China Applied science school University of Science and Technology Beijing Beijing 100083 China Department of Applied Physics and Chemistry University of Electro-Communications 1-5-1 Chofugaoka Chofu-shi Tokyo 182-8585 Japan

NiCu films about 60nm thick were deposited on MgO (001) substrates at 2.0℃ by DC plasma-sputtering at 2.7kV and 8mA in pure Ar gas using a Ni90Cu10 target. A DC bias voltage of 0, 60, 110 or 140V was applied to the substrate during deposition. The adhesion of the film to the substrate was studied using a scratch test as a function of . The application of is very effective in increasing the adhesion of the film to the substrate. In conclusion, the adhesion increases with cleaning the substrate surface by sputtering off impurity admolecules during the film initial formation due to the energetic Ar ion particle bombardment.

关键词： NiCu film plasma-sputter-deposition negative bias voltage adhesion

Comparison of Some Methods on Prediction of Activity Interaction Coefficient

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International Journal of Minerals,Metallurgy and materials 1998年第1期12卷 13-15页

作者： Changxiang Xiang Ningxin Zhang (Applied science school, {2. of science and Technology beijing, beijing 100083. china) Applied science school University of Science and Technology Beijing Beijing 100083 China

Based on Miedema's semiempirical formation enthalpy model for binary alloys, free volume theory and ageneral solution model, a new model for prediction of activity interaction coefficient ε is proposed. The calculatedresults are better in agreement with the experimental values than the two previous models. The related theories andmodels are discussed according to the degree of agreement with experimental values.

关键词： Miedema's semiempirical formation enthalpy model activity interaction coefficient free volume theory similarity coefficient

Redistribution of Boron during Ferrite Reaction in Nb-B Microalloyed Steel

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International Journal of Minerals,Metallurgy and materials 1998年第4期12卷 223-227页

作者： Shanwu Yang Xinlai He(Applied science school, {2. of science and Technology beijing, beijing 100083. china) Applied science school University of Science and Technology Beijing Beijing 100083 China

By contrast of microstructure and boron distribution in the same area of samples, the behavior of boronduring ferrite reaction in Nb-B microalloyed steel was studied. Boron atoms have segregated to original austeniteboundaries betfore ferrite reaction starts during isothermal treatment. The concentration of boron in small Pieces offerrite foming along austenite boundaries may be remarkably higher than that in austenite matrix, but it will reducegradually when the ferrite continuously grows. There is no obvious boron segregation on interface of γ/α and α/α.These facts indicate that ferrite growth is not controlled by diffusion of boron in austenite.

关键词： boron segregation ferrite reaction microalloyed steel

Preparation of semi-solid AlSi7Mg alloy slurry with big capability

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Rare Metals 2010年第6期29卷 642-645页

作者： LI Sha and MAO Weimin school of materials {2. and Engineering,university of {2. and Technology beijing,beijing 100083.china school of materials {2. and Engineering University of Science and Technology Beijing Beijing China

Semi-solid AlSi7Mg alloy slurry was prepared by low superheat pouring and weak traveling-wave electromagnetic *** effects of pouring temperature and stirring power on the microstructure of AlSi7Mg alloy slurry were *** results show that the semi-solid AlSi7Mg alloy slurry of 5 kg can be *** new technology can save energy and make the pouring process *** the pouring temperature is decreased at a stirring power of 0.41 kW,the shape of primary α-Al grains gradually changes from dendritic-like to *** the alloy melt is poured at the temperature（630°C） with a certain superheat,the pouring process becomes easier,and the spherical microstructure of AlSi7Mg alloy slurry can be prepared by the weak traveling-wave electromagnetic *** the pouring temperature is 630°C,increasing the stirring power appropriately can result in better spherical primary α-Al grains,but if the stirring power is increased to a certain value（1.72.kW）,the shape of primary α-Al grains does not obviously improve when the stirring power is continually increased.

关键词： aluminum alloys metal forming semisolid slurry electromagnetic stirring microstructure

Recycling of Spent Nickel-Cadmium Batteries

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International Journal of Minerals,Metallurgy and materials 2000年第2期14卷 126-131页

作者： Xanghua Kong Pingnan Wu(Metallurgy school, university of {2. and Technology beijing, beijing 100083. china) Metallurgy school University of Science and Technology Beijing Beijing 100083 China

A technique for recycling spent nickel-cadmium batteries, which makes separaion of cadmium and nickel possible, is developed by laboratory-scale experiments. NH3-H2.O3 aqueous solution was used in this leaching technique. Since neutralization and/or solvent extraction were not required in the separation procedure of nickel and cadmium, the closed systemizaion of the process becomespossible. Experimental results show that, (1) if the NH3 concentraion of leaching solution is sufficiently high and the ratio of H2.O3 toNH3 is properly adjusted, both Ni(OH)2.and Cd(OH)2.react with NH, and quickly dissolve into leaching solution, and (2. Ni(OH)2.can beconverted into insoluble NiO by calcination at 500℃, and CdO from Cd(OH)2.by calcination maintains good solubility in NH3-H2.O3aqueous solution. As a conclusion, the recycling technique characterized by two step leaching can be developed based on such changesin dissolution behavior by calcination. Meanwhile, the yields of 99.8% for nickel and 97.6% for cadmium are obtained, and the puritiesof Recycling of Spent Nickel-Cadmium BatterieRecycling of Spent Nickel-Cadmium Batteries Recycling of Spent Nickel-Cadmium Batteriesrecovered nickel and cadmium are 99.9% and 98.6%, respectively.

关键词： nickel-cadmium batteries recycling, ammonia leaching closed system environmental protection

Equilibrium Precipitation of Niobium Carbonitride in Austenite

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International Journal of Minerals,Metallurgy and materials 1998年第3期12卷 119-122页

作者： Fuming Wang Wenchao Li(Applied science school, {2. of science and Technology beijing, beijing 100083. china) Applied science school University of Science and Technology Beijing Beijing 100083 China

The equilibrium between niobium carbonitride and austenite has been studied. Experimentally, X-raydiffaction technique was adopted to verify that the precipitates have the same composition and structure. Theoretical-ly, Hillert and Staffansson's regular model about stoichimetric phase was used to describe the thermodynamic proper-ties of multi-component precipitate. Calculated results agree well with experimental values from literatures.

关键词： equilibrium niobium precipitate, austenite

Electrochemical Characteristic of Decarburization Reaction

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International Journal of Minerals,Metallurgy and materials 1999年第1期13卷 27-30页

作者： Xionggang Lu Fushen Li Lifen Li Kouchih Chou (Applied science school, {2. of science and Technology beijing, beijing 100083. china)(material science and Engineering school, Shanghai {2., Shanghai 2.0072. china) Applied science school University of Science and Technology Beijing Beijing 100083 China material science and Engineering {2. Shanghai University Shanghai 200072 China

The electrochemical mechanism of the reaction between Fe-C melts and CaO-SiO2.Al2.3-FeOx slag systems has been carried out. The experimental results suggest that the final content of carbon in melt increases as the partial oxygen pressure of gas decreases no matter whether there is electronic conductor or not. However, the final content of carbon in the system with electronic conductor is much lower than that without electronic conductor. It can be deduced that the transfer ability of oxygen in slag is dominated by electrons. When an electronic conductor exists, an easy pathway for the electrons is provided and the oxygen transfer rate is accelerated.

关键词： melt-slag reaction decarburization electrochemistry electronic conductor