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1.
Current-voltage characteristics of Bi2Sr2Ca2Cu3O10 tapes and bulk samples with preferentially oriented crystallites have been measured in zero applied magnetic field and for temperatures close to the mean-field critical-temperature,T
c0. It was shown that the power-law dependence,V=AI
a, valid for two-dimensional systems, does not correctly describe the data, which clearly indicate the existence of a finite critical-current density,J
c. The experimentalI-V curves are fitted quite well with the model which attributes the finite critical-current density to the coupling between the CuO2 double layers. It was found thatJ
c vanishes at a temperature value belowT
c0. This behavior can result from the occurrence of vortex fluctuation-induced layer decoupling and/or from the contribution of entropy to the vortex unbinding process. 相似文献
2.
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5.
Hot band annealing is known to be a prerequisite for good magnetic properties irrespective of manufacturing methods in grain‐oriented Fe‐3 wt.% Si electrical steels. In this study, the effects of hot band annealing on magnetic properties were investigated in 3% grain‐oriented electrical steels of low soluble AI contents and one‐stage cold rolling. Microstructure and precipitate distribution were compared with hot band annealing conditions. Secondary recrystallization behaviour with hot band annealing condition was also discussed. 相似文献
6.
The solidification structure, microstructure evolution during rolling and precipitates with nanometers in dimension of the low carbon steels produced by CSP process with thin slabs have been studied in recent years. Important differences in microstructure and mechanical properties between the CSP products and the conventional one were observed. These differences may arise from the much rapider solidification rate and cooling rate after casting of the thin slabs. Some aspects of the microstructure for the low carbon steels of the CSP thin slabs are summarized and compared with the conventional one. 相似文献
7.
分析现有参加水成球开环控制系统存在的问题,提出一种基于计算机图象识别的技术的水泥预加水成球闭环控制方法。 相似文献
8.
Xigui Song Xiufang BIAN Xiaogang Qi Xiangfa Liu Junyan Zhang Baopei Wang Limin Zhu 《北京科技大学学报(英文版)》2004,11(1)
To obtain the finer primary silicon crystals, the proprietary Al-P master alloy was adopted to modify the eutectic Al-Si alloys and the most suitable modification process was made in the experiments. The SEM (Scanning Electron Microscope) and DSC (Differential Scanning Calorimeter) analysis indicate that the Al-P modifier has more advantages over Cu-P and Fe-P modifier in easily addition, no elemental alteration and less undercooling of primary silicon′s solidification, which suggests the Al-P master alloy is an effective modifier of eutectic Al-Si alloys. 相似文献
9.
We propose a numerical simulation technique to model the process of diffusional creep and stress relaxation that occurs in
Cu-damascene interconnects of integrated circuit devices in processing stage. The mass flow problem is coupled to the stress
analysis through vacancy flux and equilibrium vacancy concentration. The technique is implemented in a software package that
seamlessly integrates the problem-oriented code with commercially available finite element program MSC.Marc. It is utilized
to model the Coble creep phenomenon by introducing the nanoscale grain boundary region having the thickness on the order of
several layers of atoms. As an illustration, the two-dimensional problem of stress relaxation in a single grain subjected
to prescribed displacements and tractions is examined. 相似文献
10.
M. KAMAYA 《Fatigue & Fracture of Engineering Materials & Structures》2004,27(6):513-521
Understanding short crack behaviour is essential for predicting the lifetime of light water reactor components. However, crack growth rates of short cracks are unsteady due to microstructural obstacles such as grain boundaries. On the other hand, the statistical behaviour of short cracks can be deduced from crack size distributions. Some papers have pointed out that the crack size distributions obtained by stress corrosion cracking tests showed a kink in the distribution line. This kink suggests that the short crack growth rate is slow compared with that of long cracks. And it can be thought that the slow growth rate is caused by the microstructural obstacles. This study investigated the influence of grain boundaries on the short crack growth behaviour of intergranular stress corrosion cracking. A crack growth simulation model, which considered the mechanical effects of the crack kink and bifurcation by grain boundaries, was developed. The crack depth distribution obtained by the simulation also exhibited a kink in the distribution line as seen in the experimental results. This suggests that grain boundaries play an important role in short crack growth behaviour. 相似文献