PANG Dexing WANG Jingtang DING Bingzhe LI Zhixian Institute of Metal Research
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Academia Sinica
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Shenyang
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China WANG Jingtang
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Professor
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Institute of Metal Research
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Academia Sinica
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Shenyang 110015
,
China
金属学报(英文版)
The glass transition in amorphous semi-conducting Se has been studied by DSC thermal ana- lysis,infrared absorption spectra and positron annihilation measurements.The results show that the glas transition seems to be reasonably explained from the viewpoints of MDS model and valence alternation pair theory proposed by Mott,Kaster et al.,respectively.
关键词:
amorphous Se
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null
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null
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null
CUI Jianzhong MA Longxiang Northeast University of Technology
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Shenyang
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China Department of Metals Forming
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Northeast University of Technology
,
Shenyang
,
China
金属学报(英文版)
The method controlling grain shape in TMT processing and the effect of grain shape on char- acteristic parameters in superplastic deformation were discussed.The accommodation velocity of grahl boundary sliding,which is the dominant mechanism in superplastic deformation,and the contribution of each mechanism to the total strain,as influenced by grain shape,were ana- lyzed.Grain shape has been shown to be an essential structural factor for superplasticity.Then an analysis was made about the effect of grain shape on the region transition strain rate so that a new concept,critical aspect for superplasticity,was worked out.These predictions were compared with the measured results in an Al-Zn-Mg alloy.
关键词:
superplastic deformation
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null
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null
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null
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null
R. P. Liu
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Z. J. Dong and Y. H. Wei( 1)Harbin Research Institute of Welding
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Harbin 150080
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China 2)National Key Laboratory of Advanced Welding Production Technology
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HIT
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Harbin 150001
,
China)
金属学报(英文版)
This paper has analyzed the influences of the heat input of welding arc, the latent heat of solidifica- tion,fluid flow of liquid metal on the heat conductivity pertaining to welding solidification crack of stainless steels. As a result,two - dimensional heat conduction models with prescribed heat flux mov- ing along the the have been developed that can simulate welding arc, convection and radiation heat loss from top and bottom surfaces of the workpiece. Finally, the finite element model was used to ana- lyze and calculate the temperature field.
关键词:
stainless steel
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null
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null
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null
田华
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李春义
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杨朝合
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山红红
催化学报
在固定床微反装置内,对动物油在USY, HZSM-5, ANA, Al2O3和SiO2催化剂上的反应行为进行了研究. 结果表明,脂肪酸酯分子一般先发生脱羧和脱羰反应(主要是 C - O 键的断裂), 初始裂化反应产生的大分子烃类及其含氧衍生物会在催化剂的酸性位上发生二次裂化和脱氧等反应. USY和HZSM-5分子筛的酸性强,有利于二次裂化,生成较多的液化气和汽油; 在具有弱酸位、大孔的Al2O3催化剂上,发生温和的二次裂化反应,转化率略低; 而在非酸性的大孔SiO2催化剂及无孔的ANA分子筛上,二次裂化反应被显著抑制,转化率更低,产物中存在大量的含氧衍生物. 热裂化反应会产生较多的CO2, 而催化裂化反应会产生相对较多的CO.
关键词:
动物油
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分子筛
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催化剂
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初始裂化
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二次裂化
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酸性
H. Pang
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Z.H. Jin
金属学报(英文版)
The microstructure of Al-Fe- V-Si-Nd alloy prepared by rapid solidification (RS) pro-cessing was studied by X-ray diffraction (XRD), transmission electron microscopy(TEM) and high resolution electron microscopy (HREM). The phase selection of thealloy during solidification and the nucleation behavior of Al8Fe4Nd phase were ana-lyzed witinin the framework of time-dependent nucleation theory. The incubation timefor Al8Fe4Nd phase was found shorter and the nucleation rate higher than those ofα-Al. The results indicate the nucleation of Al8Fe4Nd phase is heterogeneous and thedispersoids of Al8Fe4Nd form as primary particles from the liquid, which is consistentwith experimental observation.
关键词:
Al-Fe based alloy
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null
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null
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null
C. Q. Wang
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X. J. Zha
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C. Q. Zhang
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S. Q. Yang
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C. Z. Wang( 1)National Lab of Advanced Welding Technology
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HIT
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Harbin 150001
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China 2)Shanghai Institute of Metallurgy
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Chinese Academy of Science
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Shanghai 200050
,
China)
金属学报(英文版)
Solder joint reliability is one of critical problems detemining whether Sirface Mount Technology (SMT) can be used in the prohotion of important electronic products. Optimizing solder joint shape is one of effective ways to improve SMT solder joint reliability.In this paper. based on the theorem of minimum potential energy, an energy model of 3 - D solder joint shape is established,and the forma- tion of solder joint is numerically simulated by Surface Ecolver program. On the basis of the prediction of SMT solder joint shape,the mechanical model of analyzing solder joint reliability is established. An elasto - plasto - creep mateial model and its mechanical constitutive equaton are established for SnPb solder alloy, and the stress/strain response of SMT solder joint under thermal cyclical loabing is ana- lyzed with nonlinear 3 - D FEM. The fatigue life of solder joint is predicted according to Coffin- Manson fatigue life model. An integrated system for Predicting and analyzing SMT solder joint shape and reliability(PSAR) is developed.The system can analyze efficiently SMT solder joint reliability with the variation of structural parameters in the joint and give the optimal structure.
关键词:
SMT
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null
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null
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马永
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牛晓燕
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李志刚
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树学锋
兵器材料科学与工程
doi:10.3969/j.issn.1004-244X.2008.05.002
以方沸石ANA为例,采用二维轴对称有限元模型,对其纳米压痕实验进行有限元模拟,考察摩擦、压深和压头尖端半径对模拟结果的影响.摩擦因数除了对卸载后Von.Mises应力分布有很大的影响外.对模拟结果的影响较小;压深对弹性能、塑性能、硬度、弹性恢复、应力,以及压痕接触面轮廓有明显的影响;尖端半径小于150 am时对模拟结果无影响.
关键词:
方沸石ANA
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纳米压痕
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数值模拟
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接触面轮廓
XIE Changsheng SUN Peizhen ZHAO Jiansheng CHEN Yuqiu Huazhong University of Science and Technology
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Wuhan
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China XIE Changsheng Associate Professor
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Department of Mechanical Engineering No.2
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Huazhong University of Science and Technology
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Wuhan 430074
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China
金属学报(英文版)
The microstructures of Fe-Mn-Ni-Cr steels with medium carbon and the effect of alloy ele- ments on them have been investigated by means of X-ray diffraction quantitative phase ana- lyses,metallography and hardness tests.The volume fraction of martensite in steels quenched at 1100℃ can be expressed as: f_M~(1100)=162.643-15.482Mn-7.36Ni-4.286(Cr+Mo+V) Based on this expression,the quasi-equilibrium microstructure diagram has been obtained.It is shown that the effect of Mn on the austenite stability is greater than that of Ni.The equiva- lent [Ni]=2.104Mn+Ni and equivalent [Cr]=Cr+Mo+V. The driving force for martensite transformation at M_s point has been calculated to he drastically decreased by element Mn.
关键词:
quasi-equilibrium microstructure diagram
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null
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null
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