LI Yugui
,
HUANG Qingxue
,
SHEN Guangxian
,
XIAO Hong
,
PANG Siqin
,
WANG Jianmei
钢铁研究学报(英文版)
With rollers as elastic bodies and workpieces as elastoplastic bodies, the rolling problem can be viewed as a friction elasticplastic contact problem. With fewer assumptions in the simulation of striprolling process, a boundary element method (BEM) for twodimensional elastoplastic finite strain and finite deformation analysis of contact problems with friction was presented. All the equations for contact problems, which include multinonlinearities, were obtained. Incremental and iterative procedures were used to find contact pressure and friction stress. Moreover, initial strain rate algorithm and workhardening material behavior can be assumed in the plastic analysis. Several examples were presented, and the results of contact pressure and friction stress were in excellent agreement with those of analysis.
关键词:
boundary element method;contact problem;elastoplastic finite deformation;rolling
Materials Research Bulletin
Through analysis of the latest experimental results reported in the literature and obtained in our laboratory, we have extended our previous quantum confinement/luminescence center model for the photoluminescence mechanism of porous Si and of nanometer-silicon-particle-embedded Si oxide films (G.G. Qin and Y.Q. Jia, Solid State Commun. 86, 559 (1993)). We consider that there are three main types of competitive photoexcitation/photoemission processes and that the process in which photoexcitation occurs in the nanometer silicon particles (NSPs) while photoemission occurs in the luminescence centers (LCs) in the SiOx layers very close to the NSPs is usually the major one. We discuss under what conditions the other two types of processes will dominate. We believe that the extended quantum confinement/luminescence center model is a physical model that is suitable for the photoluminescence from silicon oxide films embedded with NSPs or nanometer Ge particles (NGPs), as well as from oxidized porous Si. (C) 1999 Elsevier Science Ltd.
关键词:
oxides;luminescence;defects;blue-light emission;visible luminescence;optical-properties;nanocrystals;mechanism;dependence;sio2-films;absorption;spectra;defects
Applied Physics Letters
The Si/Si oxynitride superlattices, with three periods, have been grown using the two-target alternation magnetron sputtering technique. The thicknesses of Si oxynitride layers and Si layers in the superlattices are 2.0 and 1.4 nm, respectively. Visible electroluminescence (EL) from a semitransparent Au film/(Si/Si oxynitride) superlattice/p-Si structure has been observed. Each EL spectrum of the structure has a dominant peak around 640 nm, a weaker peak around 520 nm, and a shoulder around 820 nm. By comparing the EL from the semitransparent Au film/(Si/Si oxynitride) superlattice/p-Si structure with that from a semitransparent Au film/Si oxynitride film/ p-Si structure, we found that the EL efficiency of the former structure is about 2-4 times of that of the latter one. (C) 1998 American Institute of Physics.
关键词:
chemical-vapor-deposition;silicon-nitride films;optical-properties;spectra
Physica Status Solidi a-Applied Research
The interdiffusion of Mo-Si and Ti-Si multilayers is investigated by an in situ X-ray diffraction technique. It is found that the behavior of the interdiffusion in both multilayers is quite different. Both positive and negative interdiffusion take place in Ti-Si multilayers during annealing, while only positive interdiffusion occurs in Mo-Si multilayers. Accompanying interdiffusion, the process of solid state amorphization reaction plays a dominant role in Ti-Si multilayers, on the contrary, the crystallization process was the main process in Mo-Si multilayers. In addition, a transient amorphization process at early stage of annealing is observed in Mo-Si multilayers for the first time.
关键词:
amorphous si;alloy;films;phase
文娇
,
刘畅
,
俞文杰
,
张波
,
薛忠营
,
狄增峰
,
闵嘉华
功能材料与器件学报
利用高分辨率X射线衍射(HRXRD)和拉曼光谱(Raman spectrum)研究了由扩散引起Si/SiGe/Si异质结中Si/SiGe异质界面互混的现象.结果表明:应变弛豫前Si/SiGe异质界面互混程度随热载荷的增加而增强;Si/SiGe异质界面的硼(B)浓度梯度抑制了界面互扩散.总之,Si/SiGe互扩散作用越强诱发Si/SiGe异质界面越粗糙,从而导致器件性能恶化.
关键词:
Si/SiGe互扩散
,
热载荷
,
硼浓度梯度
材料科学技术（英文）
By Ar+ sputtering onto Si wafers which were surrounded by Mo plates, uniform cones over a large area on the Si surface were formed. Scanning electron microscopic study showed that the cones were formed on the entire surface of the Si wafer. The dimensions of the uniform cones were one micrometer in diameter and 5similar to6 micrometer's high. They were further characterized by means of cross-sectional transmission electron microscopy, with the technique of micro-diffractions. It was found that the cone contained a pure Si regime and a Mo-rich regime. In the binary Mo-Si zone, we identified three distinct areas vertically: (1) domains of Mo-induced Si ordered structures, (2) a small volume of a new Mo3Si2 structural variant, intergrown with the Si ordered structure, and (3) a small amount of pure Mo nanoparticles covering the surface of the cones. The formation of the large and uniform cones may provide a new surface configuration for potential applications in surface science and technology.
关键词:
Si cones;ordered structure;Mo silicide;copper seed cones;resolution electron-microscopy;surface;growth
X.L.Ma
,
N.G.Shang
,
C.S.Lee
,
S.T.Lee
材料科学技术（英文）
By Ar+ sputtering onto Si wafers which were surrounded by Mo plates, uniform cones over a large area on the Si surface were formed. Scanning electron microscopic study showed that the cones were formed on the entire surface of the Si wafer. The dimensions of the uniform cones were one micrometer in diameter and 5~6 micrometers high. They were further characterized by means of cross-sectional transmission electron microscopy, with the technique of micro-diffractions. It was found that the cone contained a pure Si regime and a Mo-rich regime. In the binary Mo-Si zone, we identified three distinct areas vertically: (1) domains of Mo-induced Si ordered structures, (2) a small volume of a new Mo3Si2 structural variant, intergrown with the Si ordered structure, and (3) a small amount of pure Mo nanoparticles covering the surface of the cones. The formation of the large and uniform cones may provide a new surface configuration for potential applications in surface science and technology.
关键词:
Si cones
,
null
,
null
Kai TANG
,
Merete Tangstad
金属学报(英文版)
Phase equilibria in the Si-rich domain of the Si-Fe system have been reassessed based on the recent DTA experimental results. Thermodynamic properties of liquid phase have been reassessed using the associated solution model. The properties of DIAMOND_A4 mixture phase have been added in order to evaluate the phase equilibria for the pure silicon materials. The assessed system is able to reproduce the experimental values in the whole composition range of the Si-Fe system.
关键词:
Si-Fe; Thermodynamic
,
null
,
null
,
null
Xiangxin XUE
,
Yinchang CHE and Hegui DU(Department of Metallurgy
,
Northeastern University
,
Shenyang
,
110006
,
China)
材料科学技术（英文）
Activitibs of Si in binary Cu-Si and ternary Cu-Ti-Si melts were measured at 1 550℃ by using a method of chemical equilIbrium between gas and liquid. The activity interaction coefficients of Si in the melts have been determined from the experimental data (lny = -5.69. s = 6.69. P2: = -26.22. E; =-43.96) and activity interaction coefficients of Ti in binary Cu-Ti melt at 1550℃ has been estimated from Sommer's data based on the regular solution model (lny =-1 .10. : = 2.95.p:=-2.10).
关键词:
Scripta Materialia
Three-dimensional atom probe has been applied to investigate the solubility of Si in Al(3)SC in an Al-0.16Sc-0.05Si alloy. It was found that L1(2)-structured Si-containing Al(3)Sc precipitates formed after the alloy was aged at 300 degrees C. Results of first-principles calculation indicated that Si atoms tend to substitute Al sites in Al(3)Sc, and thus the precipitates can be represented as (Al,Si)(3)Sc. The (Al,Si)(3)SC was found to have a dramatic precipitation-strengthening effect in the cast alloy. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
关键词:
Aluminium alloys;Ageing;3DAP;Precipitation;Hardness test;aluminum-alloys;coherency loss;evolution;zr
