XU Yourong ZHANG Henghua CHEN Darning XIE Fuchun XU Mingyu Shanghai University of Science and Technology
,
Shanghai
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ChinaCHEN Lanying SU Baorong QIAN Hongbin Shanghai Optics and Fine Mechinery Research Institute
,
Academia Sinica
,
Shanghai
,
China XU Yourong
,
professor
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Department of Materials Science and Engineering
,
Shanghai University of Science and Technology
,
Shanghai 201800
,
China
金属学报(英文版)
Effect of laser scanning speed on phase constitution,microstructure,microhardness and wear resistance of laser-cladding hard facing alloy Stellite 12 has been investigated by means of a cross-flow-type CO_2 laser of 1.5 kW.The laser-cladding layer on the alloy consists of ma- trix phase of suppersaturated solid solution γ(Co,Cr)and complex hexagonal carbide M_7C_3.Under certain condition,at higher laser scanning speed,the suppersaturated solubility of elements increases in γ(Co,Cr),and the precipitation of the complex carbtde M_7C_3 de- creases,so the microhardness increases and the wear resistance decreases.But at slower laser scanning speed,more complex carbide M_7C_3 may precipitate,and the wear resistance may be improved.Therefore,it is believed that the principal factor in improving wear resistance is the precipitation of carbide M_7C_3,while increment of microhardness is the suppersaturated solu- bility of elements in matrix phase γ(Co,Cr).
关键词:
laser-cladding
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null
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null
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null
LI Laifeng XING Zhongshu Institute of Metal Research
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Academia Sinica
,
Shenyang
,
China XING Zhongshu
,
professor
,
Institute of Metal Research
,
Academia Sinica
,
Shenyang 110015
,
China
金属学报(英文版)
The solubilities of Ce,Nd and Y in α-Fe at 873 to 1153 K have been deter mined by means of electron microprobe quantitative analyses.The temperature dependences of the solubilities were obtained from the experimental data.The results have been compared with those deter- mined by three other technigues,very good agreement was obtained between the results of all these techniques.
关键词:
α-Fe
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null
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null
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null
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null
SUN Jian LIN Dongliang Shanghai Jiaotong University
,
Shanghai
,
China LIN Dongliang
,
professor
,
Department of Materials Science
,
Shanghai Jiaotong University
,
Shanghai 200030
,
China
金属学报(英文版)
Equilibrium equation of point defects in Ll_2 type intermetallic compounds was established to calculate the relations of the concentration of antisite defects and vacancies and bulk composi- tion in Ni_3Al.The examination of temperature effects on the point defects cleared up the mis. understanding of the properties of the“constitutional point defects”in Ni_3Al.
关键词:
intermetallic compound
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null
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null
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Campbell Laird(Dept. of Materials Science & Engineering
,
University of Pennsylvania
,
Philadelphia
,
PA 19104-6272
,
USA)Pedro Peralta(Center for Materials Science
,
Los Alamos National Laboratory
,
MaU Stop K765
,
Los Alamos
,
NM 87545-0001
,
USA)
材料科学技术（英文）
The mechanisms of fatigue crack propagation are breifly reviewed in relation to Professor McClintock's contributions to the early development of the field. The most securely established understanding has been obtained for those mechanisms of propagation involving plasticity-inducedgeometrical changes to the crack tip during tensile and compressive straining (the plastic blunting process). The roles of more complex factors in controlling the kinetics of crack propagation,which cause the magnitude of the Paris exponent to exceed 2, remain to be elucidated. Recentlyobtained results revealing the interconnection between the slip behaviour at the crack tip, theplastic blunting process and the dislocation structures present in the material before the crackencounters them are reported.
关键词:
WU Chuansong
,
CAO Zhenning
,
WU Lin Harbin Institute of Technology
,
Harbin
,
China
金属学报(英文版)
A model is established to analyze three-dimensional fluid flow and heat transfer in TICweld pools with full penetration.It considers the deformation of the molten pool surfaceat the condition of full penetrated workpieees,takes the are pressure as the drivingforce of the pool surface deformation,and determines the surface configuration of weldpool based on the dynamic balance of arc pressure,pool gravity and surface tension atdeformed weld pool surface. The SIMPLER algorithm is used to calculate the fluid flowfield and temperature distribution in TIG weld pools of stainless steel workpieces.TIGwelding experiments are made to verify the validity of the model.It shows the calculatedresults by the model are in good agreement with experimental measurements. professor,Dept of Welding Engineering,Harbin Institute of Technology,Harbin 150006,China
关键词:
KEY WORDS TIG weld pool
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null
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null
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null
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International Journal of Hydrogen Energy
Various carbon additives were mechanically milled with LiBH(4)/MgH(2) composite and their hydrogen storage behaviors were investigated. It was found that most of the carbon additives exhibited prominent effect on the host material. Among the various carbon additives, purified single-walled carbon nanotubes (SWNTs) exhibited the most prominent effect on the kinetic improvement and cyclic stability of Li-Mg-B-H system. Results show that LiBH(4)/MgH(2) composite milled with 10 wt.% purified SWNTs additive can release nearly 10 wt.% hydrogen within 20 mm at 450 degrees C, which is about two times faster than that of the neat LiBH(4)/MgH(2) sample. On the basis of hydrogen storage behavior and structure/phase investigations, the possible mechanism involved in the property improvement upon carbon additives was discussed. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.
关键词:
Hydrogen storage;Lithium borohydride;MgH(2);Carbon;Mechanical;milling;arc-discharge method;libh4;nanotubes;composites;hydride
International Journal of Hydrogen Energy
Identification of effective catalyst is a subject of great interest in developing MgH(2) system as a potential hydrogen storage medium. In this work, the effects of typical titanium compounds (TiF(3), TiCl(3), TiO(2), TiN and TiH(2)) on MgH(2) were systematically investigated with regard to hydrogen sorption kinetics. Among them, adding TiF(3) leads to the most pronounced improvement on both absorption and desorption rates. Comparative studies indicate that the TiH(2) and MgF(2) phases in situ introduced by TiF(3) fail to explain the superior catalytic activity. However, a positive interaction between TiH(2) and MgF(2) is observed. Detailed comparison between the effect of TiF(3) and TiCl(3) additive suggests the catalytic role of F anion. XPS examination reveals that new bonding state(s) of F anion is formed in the MgH(2) + TiF(3) system. On the basis of these results, we propose that the substantial participation of F anion in the catalytic function contributes to the superior activity of TiF(3). (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.
关键词:
Hydrogen storage;Kinetics;Hydride;Catalyst;aluminum hydrides;storage materials;magnesium;improvement;composite;metals;nb2o5;tif3;fe
