E.L. Zhang
,
B.Yang
,
S.Y. Zeng and Q.C. Li(School of Materials Science and Engineering
,
Harbin Institute of Technology
,
BOX 428
,
Harbin 150001.)China)M.Z.Ma (Jiamusi University Jiamusi 154002
,
China)
金属学报(英文版)
The reaction process and mechanistn of reaction synthesis of TiC in Al-Ti-C system have been investigated in detail by observing the microstructure of the water quenched preform with SEM and EDX. The results showed that the reaction processing can be divided into three stages: aluminium powder is melted firstly, then titanium dissolves in the melted aluminium and Al3Ti is formed around titanium powder, titanium concentrates around carbon powder and a Ti-rich layer is observed around carbon pariicles,in which titanium atom reacts with carbon atom to synthesize TiC;TiC precipitates out of the melt, and diffuses out of the layer. A solution-precipitation mechanism and a reaction model were set up based on the experimental results.
关键词:
kinetic process
,
null
,
null
,
null
Solid State Communications
Considering the image potential, we calculate the binding energies of a shallow donor impurity placed on the centre of a quantum box using the variational approach. The results we have obtained show that there is a great difference of the effects of image potential between the cases including impurity ion image potential and including the image potentials of impurity ion and electron simultaneously. The results also show that the image potential is important, especially when the dimensions of quantum box become small.
关键词:
well;gaas-ga1-xalxas;states
L. H. Lang
,
D. C. Kang
,
S. H. Zhang
,
Z. R. Wang
,
S. J. Yuan
,
K. B. Nielsen and J. Dancket 1) Department of Materials Engineering
,
Harbin Institute of Technology
,
Harbin 150001
,
China 2) Aalberg University
,
Denmark
金属学报(英文版)
In this paper, the forming features of tapered rectangular box during hydrodynamic deep drawing are studied by means of FEM.The effect rules of square blank corner corner amount on body wrinkling are recognized and corresponding methods are discussed. At last, the results of FEM are verified by experi- ment.
关键词:
sheet metal forming
,
null
,
null
Qunqiang FU
材料科学技术（英文）
At first, a series of finite element method (FEM) simulation tests were used to find the critical forming conditions of hot-galvanized sheet steel during the rectangular box drawing processing when constant blank holder forces were applied. According the test results, the reasonable alteration scope of initial variable blank holder force (VBHF) was as 1.9~2.3 T. Then, based on the test productions of blank holder force, 12 typical VBHF curves were applied to perform the simulation tests by the simulation software of DYNAFORM. The simulation test results showed that VBHF had great effects on drawing formability of hot-galvanized sheet steel during the rectangular box drawing. However, the different VBHF curves were applied to control the whole drawing and it would get great different effects. At the same tine, the VBHF had great effects on the maximum thick thinning ratio, but had little effect on the maximum thick incrassation ratio. So, reasonable application of the VBHF would greatly decrease the fractures. When the VBHF profile is taken as curve L, the best effect of drawing formability could be obtained. When curve I is used, contrary effect could be gotten. The other types of curves would cause effects between above two types of VBHF curves. Finally, the actual tests were applied to check the validity of the FEM simulation tests. The results show that the FEM simulation tests are good ways for predicting and optimizing the VBHF.
关键词:
Drawing process
,
变压边力
,
热镀锌钢板
王茹
,
张正选
,
俞文杰
,
毕大炜
,
陈明
,
刘张李
,
宁冰旭
功能材料与器件学报
doi:10.3969/j.issn.1007-4252.2011.02.017
本研究工作采用硅离子注入和高温退火工艺对SIMOX材料的BOX层进行总剂量辐射加固.辐射实验结果证明了该加固方法的有效性.PL谱和HRTEM图像显示了硅离子注入及退火工艺在材料的BOX层中引入了Si纳米晶,形成电子陷阱能级,有效俘获电子,从而提高了材料BOX层的抗总剂量辐射能力.
关键词:
绝缘体上硅
,
注氧隔离
,
总剂量辐照
,
纳米晶
Microelectronics Journal
The Stark shift of the electronic energy levels in semiconducting rectangular quantum boxes with different sizes is investigated by the use of variational solutions to the effective-mass approximation for electric fields of various orientations with respect to the center axis of the box. The asymptotic expansions of the Stark shift are given in the limits of low and high fields, respectively; they clearly indicate that the Stark shift is a quadratic function of the electric field for low electric fields and is an approximate linear function of the electric field for high electric fields. Likewise, our results also show that the largest Stark shift is obtained for the field directed along the diagonal in a cubic box, and is found for the low field directed along a side of the box and for the high field along the diagonal in a rectangular one. The large Stark shift of the electron and hole trapped in a quantum box leads to an obvious reduction of the interband recombination. (C) 2008 Elsevier Ltd. All rights reserved.
关键词:
quantum boxes;Stark effect;optical-absorption;exciton energies;field;well;wires
李敏
,
王树元
,
彭友舜
,
秦秀娟
,
邵光杰
电镀与精饰
doi:10.3969/j.issn.1001-3849.2011.03.002
以辛基酚聚氧乙烯(10)醚为有机添加剂,阴极电沉积制备了ZnO薄膜.经超声处理后,用X-射线衍射仪和光致发光光谱仪研究了ZnO薄膜的结构、应力状态和发光性能的变化.结果表明:样品的结晶性能变差,晶格内部的压应力变为张应力,于λ=395 nm处的激子发光峰和λ=580nm处的黄光发光峰强度比减小,同时发光谱中又出现了于λ=428 nm的蓝光峰.分析认为λ位于580 nm处的黄光发射是由VoZni复合缺陷与价带顶的跃迁引起的,而λ位于428 nm的蓝光发射则是由Zni与价带顶之间的跃迁引起.
关键词:
ZnO薄膜
,
超声处理
,
缺陷
,
光致发光
