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排序方式: 共有1806条查询结果,搜索用时 234 毫秒
1.
Wang Xuping Wang Jiyang Hu Xiaobo Zhang Jianxiu Zhao Hongyang Huang Wanxia Zhu Peiping 《中国稀土学报(英文版)》2006,24(Z1)
Langasite single crystal was grown by the Czochralski method and its perfection was assessed by white beam synchrotron radiation topography. It is found that the growth core and the growth striations are the primary growth defects and they show strong X-ray kinematical contrast in the topographs. Another typical defect in LGS crystal is dislocation. The formation mechanisms of these growth defects in LGS crystals were discussed. 相似文献
2.
对三种组织状态的F-M复相钢进行了对称和非对称循环加载条件下的形变研究.结果表明,双相钢的循环变形行为,不仅与组织中位错组态的演变过程有关,同时也受循环载荷大小、类型以及加载方式所影响.分析表明,双相钢的循环硬化、软化行为主要受控于两个基本过程,即循环变形时位错组态演变的物理过程和相间分载应力的转嫁、相间残余应力变化的力学过程. 相似文献
3.
A self‐consistent texture model is implemented in the finite‐element code ABAQUS/Explicit®. Hardening of the slip systems is described by evolution laws for dislocation densities, and the Bauschinger effect is included. With these ingredients the cold rolling of an IF‐steel is simulated and the evolution of texture and anisotropy is examined. The use of the dislocation based hardening law is found to have a significant effect on the evolution of the anisotropic yield surface, but only very little influence on the texture. Furthermore, the hardening model is used to investigate the evolution of dislocation densities in differently oriented grains during plane strain compression. It is found that the dislocation density varies greatly depending on orientation, an observation which can help to explain the orientation dependence of recrystallization. 相似文献
4.
运用电子显微分析和波谱分析等方法对GH2027合金的第二相进行了研究,结果表明,合金晶界相主要是片状M6C和薄膜状M23C6,经波纹图样测得其错配度约为3%,晶内M6C和M23 相似文献
5.
Displacement Discontinuity Method for Fracture Mechanics Analysis of Reissner Plates: Static and Dynamic 总被引:1,自引:0,他引:1
This paper is concerned with the displacement discontinuity method applied to the shear deformable plates (Reissner’s and
Mindlin’s theories) with cracks subjected to static and dynamic loads. Fundamental solutions of dislocation are derived using
the Fourier transform method and the Laplace transformation technique. Boundary integral equations are presented in terms
of rotations/displacement on the crack surfaces. The Chebyshev polynomials of the second kind are used to evaluate the integral
equations with hypersingular kernels on the crack boundaries and determine the stress intensity factors at the crack tips.
Comparisons are made with other numerical solutions to demonstrate the proposed method is accurate both for static and dynamic
problems. 相似文献
6.
Yukio Sato Tomohito Tanaka Fumiyasu Oba Takahisa Yamamoto Yuichi Ikuhara Taketo Sakuma 《Science and Technology of Advanced Materials》2003,4(6):137
SrTiO3 and ZnO bicrystals with various types of boundaries were fabricated in order to examine their current–voltage characteristics across single grain boundaries. Their grain boundary structures were also investigated by high-resolution transmission electron microscopy. In Nb-doped SrTiO3, electron transport behaviors depend on the type of boundaries. Random type boundaries exhibit highly non-linear current–voltage characteristics, while low angle boundaries show a slight non-linearity. On the contrary, undoped ZnO does not exhibit non-linear current–voltage characteristics in any type of boundaries including random ones. It is suggested that the differences observed in current–voltage properties between the two systems are mainly due to the difference in the accumulation behavior of acceptor-like native defects at grain boundaries. A clear non-linearity is obtained by means of Co-doping even for the highly coherent Σ1 boundary in a ZnO bicrystal. This is considered to result from the production of acceptor-like native defects by Co-doping. 相似文献
7.
8.
K. Nakano S. Tomiya M. Ukita H. Yoshida S. Itoh E. Morita M. Ikeda A. Ishibashi 《Journal of Electronic Materials》1996,25(2):213-216
Using electroluminescence (EL) topography and transmission electron microscopy (TEM), we investigated the nonluminescent regions
which form while current is being injected into ZnMgSSe/ZnSSe/ZnCdSe-based blue light emitters. Small dark spots were observed
just after turn-on and spread out forming rough nonluminescent triangles in the <100> directions in the EL image of the active
region. TEM studies showed that the small dark spots are pre-existing stacking faults originating at the substrate/epitaxial
layer interface. The nonluminescent triangles were found to be a dense region of dislocation dipoles and dislocation loops.
Each dipole was aligned along two <110> directions in the {111} planes. The Burgers vectors were of the type a/2<011> inclined
at 45° to the (001) junction plane. 相似文献
9.
10.