30Cr1Mo1V钢蠕变性能研究

测试了３０Ｃｒｆ１Ｍｏ１Ｖ钢的蠕变极限，通过透射电镜对稳态是为阶段位错的结构、分布、组态及其运动方式进行了探讨。试验结果表明，蠕变稳态阶段位错的运动是以滑移为主，稳态蠕变速率受位错的攀移控制。     

A dislocation-density-based 3D crystal plasticity model for pure aluminum

A dislocation-density-based crystal plasticity finite-element model (CPFEM) is developed in which different dislocation densities evolve. Based upon the kinematics of crystal deformation and dislocation interaction laws, dislocation generation and annihilation are modeled. The CPFEM model is calibrated for pure aluminum using experimental stress–strain curves of pure aluminum single crystal from the literature. Crystallographic texture predictions in plane-strain compression of aluminum are validated against experimental observations in the literature. The framework is implemented in ABAQUS with user interface UMAT subroutine.     

Continuum and atomistic modeling of electromechanically-induced failure of ductile metallic thin films

A multiscale modeling approach is presented for the analysis of electromechanically-induced void morphological evolution and failure in ductile metallic thin films, which are used for device interconnections in integrated circuits. Self-consistent mesoscopic simulations of surface morphological evolution are combined with atomistic calculations of surface properties and molecular-dynamics (MD) simulations of plastic deformation mechanisms in the vicinity of void surfaces. Results are presented that demonstrate a coupled mode of surface instability that leads to formation of electromigration-induced slit-like features and stress-induced crack-like features on void surfaces. In addition, MD results are presented for the dislocation-mediated mechanism and the kinetics of void growth in ductile metallic systems subject to hydrostatic and biaxial tensile strains. The incorporation of MD-derived constitutive information for plastic deformation into the mesoscopic analysis and simulation framework also is discussed.     

Crack induced slip processes in 3D

The paper presents three-dimensional molecular dynamic simulations of bcc iron single crystals with embedded cracks of two different orientations. The cracks are loaded in tension mode I. The results show that crack stability or crack growth is significantly influenced by the temperature and mutual orientation of the crack and slip planes at the crack front. Various slip processes induced by the crack may have different consequences for crack stability. The results from molecular dynamic simulations are compared with continuum models, experimental observations, and our previous plane strain simulations.     

Dislocation mobility and electronic effects in semiconductor compounds

In situ transmission electron microscopy experiments provide a unique way to investigate in real time the dislocation behaviour at a microscopic scale and to decide which elementary process controls the dislocation glide in semiconductors. In this review the experimental results obtained on different semiconductors are presented and discussed. Particular attention is devoted to the radiation-enhanced glide process.     

Passivation and gettering of defective crystalline silicon solar cell

Different polycrystalline silicon and single-crystalline silicon with dislocations were used for passivation and gettering processes. These materials have defects and more impurity in the crystal. The dominant increase of electronic performance was found for wafers with more defects by using a different casting method. The wafers of single crystalline silicon with dislocations also have higher increase of efficiency of cell in comparison with that wafer without dislocations during oxide passivation processes used. POCl₃ was used for gettering processes. Single-crystal wafer with or without dislocations was used for comparison of gettering.     

Electro-elastic stress analysis for a wedge-shaped crack interacting with a screw dislocation in piezoelectric solid

The electro-elastic stress investigation on the interaction problem of a screw dislocation near the tip of a semi-infinite wedge-shaped crack in piezoelectric material has been carried out. Explicit closed-form analytical solutions are obtained for the stress intensity factor (SIF) and the electric displacement intensity factor (EDIF) of the crack, as well as the force on dislocation. The derivation is based on the conformal mapping method and the perturbation technique. The dislocation has Burger's vector normal to the isotropic basal plane, with a line force and a line charge being applied at the core of the dislocation. The influence of the location and the wedge angle of the crack on the image force of the dislocation has been discussed in detail. At the same time the effect of the dislocation on the crack behavior has been also examined under different configurations. Two types of PZT materials are used to numerically illustrate the influences of the wedge angle and the location of the dislocation on the image force and the crack intensities. Results obtained in the current study can be fully reduced to various special cases available in the literatures.     

Internal friction in microcrystalline magnesium reinforced by alumina particles

Using internal friction measurement, changes in the microstructure of microcrystalline magnesium and magnesium with 3 vol.% of Al₂O₃ microparticles and nanoparticles, due to thermal treatment, have been investigated. Materials have been thermally treated at increasing temperature and then the amplitude dependence of the logarithmic decrement was measured at room temperature. The thermal treatment influences the amplitude-dependent component of the decrement in composite with nanoparticles while in composite with microparticles no influence has been estimated. Thermal stresses induced in the composites due to a difference between thermal expansion coefficient of matrix and ceramic particles may create new dislocations during the cooling from elevated temperatures. Density of new dislocations depends on the particle size. The thermal stresses can achieve yield stress in the matrix and micro-glide of newly created dislocations as well as their annihilation may occur.     

Microstructure Studies of GaInAsSb/GaSb Heterostructure

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