Copper single crystal specimens with the longitudinal axis parallel to the [013] double-slip-orientation were grown through Bridgman technique. The fatigue tests were performed using a symmetric tension-compression lo...Copper single crystal specimens with the longitudinal axis parallel to the [013] double-slip-orientation were grown through Bridgman technique. The fatigue tests were performed using a symmetric tension-compression load mode at room temperature in an open-air and a 0.5 mol/L NaCl solution, respectively. The dislocation microstructures were observed with scanning electron microscopy (SEM) by the electron channeling contrast (ECC) and transmission electron microscopy (TEM). The results show that the saturation dislocation microstructures during the corrosion fatigue in the aqueous solution of 0.5 mol/L NaCI, mainly consisted of labyrinth, wall and vein dislocation structures, which differs from the dislocation structures of the walls and veins in an open-air environment.展开更多
By combining grain boundary (GB) and its influence zone, a micromechanic model for polycrystal is established for considering the influence of GB. By using the crystal plasticity theory and the finite element method f...By combining grain boundary (GB) and its influence zone, a micromechanic model for polycrystal is established for considering the influence of GB. By using the crystal plasticity theory and the finite element method for finite deformation, numerical simulation is carried out by the model. Calculated results display the microscopic characteristic of deformation fields of grains and are in qualitative agreement with experimental results.展开更多
A dislocation interaction model has been proposed for cyclic deformation of fcc crystals.Ac- cording to this model,cyclic stress-strain responses and saturation dislocation structures of a crystal are associated with ...A dislocation interaction model has been proposed for cyclic deformation of fcc crystals.Ac- cording to this model,cyclic stress-strain responses and saturation dislocation structures of a crystal are associated with the modes and intensities of dislocation interactions between slip systems active in the crystal; and,hence,may be predicted by the location of its tensile axis in the crystallographic triangle.This model has successfully explained the different behaviours of double-slip crystals and multi-slip behaviours of some crystals with orientations usually con- sidered as single-slip ones.展开更多
The symmetrical push-pull fatigue tests at strain amplitude of 2×10~3 with different slip orientation of Al single crystals,were carried out at room temperature in air.The peak stresses of various cycles were mea...The symmetrical push-pull fatigue tests at strain amplitude of 2×10~3 with different slip orientation of Al single crystals,were carried out at room temperature in air.The peak stresses of various cycles were measured and the stress-strain hysteresis loops for selected cy- cles were recorded.The energy losses.friction stresses,back stresses and shape展开更多
Cyclic stress-strain responses and dislocation structure of copper single crystals with various tensile axes were systematically studied and compared with each other.Experimental results reveal that the evolution of m...Cyclic stress-strain responses and dislocation structure of copper single crystals with various tensile axes were systematically studied and compared with each other.Experimental results reveal that the evolution of microscopic dislocation configurations in a crystal and, accordingly,its macroscopic cyclic behaviours are closely related with its orientation.Re- markable secondary slip has been observed in some crystals with orientations well inside the crystallographic triangle, which are usually considered as single-slip ones.Their cyclio behaviours and dislocation structures at saturation are similar to those of their neighbouring multi-slip crystals.These results have constructed the experimental basis for the newly pro- posed dislocation interaction model Jor cyclic deformation of fee crystals,which will be des- cribed in the second part of this article.展开更多
文摘Copper single crystal specimens with the longitudinal axis parallel to the [013] double-slip-orientation were grown through Bridgman technique. The fatigue tests were performed using a symmetric tension-compression load mode at room temperature in an open-air and a 0.5 mol/L NaCl solution, respectively. The dislocation microstructures were observed with scanning electron microscopy (SEM) by the electron channeling contrast (ECC) and transmission electron microscopy (TEM). The results show that the saturation dislocation microstructures during the corrosion fatigue in the aqueous solution of 0.5 mol/L NaCI, mainly consisted of labyrinth, wall and vein dislocation structures, which differs from the dislocation structures of the walls and veins in an open-air environment.
文摘By combining grain boundary (GB) and its influence zone, a micromechanic model for polycrystal is established for considering the influence of GB. By using the crystal plasticity theory and the finite element method for finite deformation, numerical simulation is carried out by the model. Calculated results display the microscopic characteristic of deformation fields of grains and are in qualitative agreement with experimental results.
文摘A dislocation interaction model has been proposed for cyclic deformation of fcc crystals.Ac- cording to this model,cyclic stress-strain responses and saturation dislocation structures of a crystal are associated with the modes and intensities of dislocation interactions between slip systems active in the crystal; and,hence,may be predicted by the location of its tensile axis in the crystallographic triangle.This model has successfully explained the different behaviours of double-slip crystals and multi-slip behaviours of some crystals with orientations usually con- sidered as single-slip ones.
文摘The symmetrical push-pull fatigue tests at strain amplitude of 2×10~3 with different slip orientation of Al single crystals,were carried out at room temperature in air.The peak stresses of various cycles were measured and the stress-strain hysteresis loops for selected cy- cles were recorded.The energy losses.friction stresses,back stresses and shape
文摘Cyclic stress-strain responses and dislocation structure of copper single crystals with various tensile axes were systematically studied and compared with each other.Experimental results reveal that the evolution of microscopic dislocation configurations in a crystal and, accordingly,its macroscopic cyclic behaviours are closely related with its orientation.Re- markable secondary slip has been observed in some crystals with orientations well inside the crystallographic triangle, which are usually considered as single-slip ones.Their cyclio behaviours and dislocation structures at saturation are similar to those of their neighbouring multi-slip crystals.These results have constructed the experimental basis for the newly pro- posed dislocation interaction model Jor cyclic deformation of fee crystals,which will be des- cribed in the second part of this article.
