A crystal plasticity finite element model was developed for the drawing deformation of pure copper micro wire,based on rate-dependent crystal plasticity theory.The impact of wire diameter compression ratio on the micr...A crystal plasticity finite element model was developed for the drawing deformation of pure copper micro wire,based on rate-dependent crystal plasticity theory.The impact of wire diameter compression ratio on the micro-mechanical deformation behavior during the wire drawing process was investigated.Results indicate that the internal deformation and slip of the drawn wire are unevenly distributed,forming distinct slip and non-slip zones.Additionally,horizontal strain concentration bands develop within the drawn wire.As the wire diameter compression ratio increases,the strength of the slip systems and the extent of slip zones inside the deformation zone also increase.However,the fluctuating stress state,induced by contact pressure and frictional stress,results in a rough and uneven wire surface and diminishes the stability of the drawing process.展开更多
Single-crystalline Ga-doped SnO2 nanowires and SnO2：Ga2O3 heterogeneous microcombs were synthesized by a simple one-step thermal evaporation and condensation method. They were characterized by means of X-ray powder d...Single-crystalline Ga-doped SnO2 nanowires and SnO2：Ga2O3 heterogeneous microcombs were synthesized by a simple one-step thermal evaporation and condensation method. They were characterized by means of X-ray powder diffraction （XRD）, field-emission scanning electron microscopy （FE-SEM）, energy-dispersive X-ray spectroscopy （EDS）, transmission electron microscopy （TEM） and selected-area electron diffraction （SAED）. FE-SEM images showed that the products consisted of nanowires and mierocombs that represent a novel morphology. XRD, SAED and EDS indicated that they were single-crystalline tetragonal SnO2. The influence of experimental conditions on the morphologies of the products is discussed. The morphology of the product showed a ribbon-like stem and nanoribbon array aligned evenly along one or both side of the nanoribbon. It was found that many Ga2O3 nanoparticles deposited on the surface of the microcombs. The major core nanoribbon grew mainly along the [110] direction and the self-organized branching nanoribbons grew epitaxially along [110] or [110] orientation from the （110） plane of the stem. A growth process was proposed for interpreting the growth of these remarkable SnO2：Ga2O3 heterogeneous microcombs. Due to the heavy doping of Ga, the emission peak in photoluminescence spectra has red-shifted as well as broadened significantly.展开更多
Mechanical properties, corrosion behavior and hydrogen absorption of zirconium alloys are related to the texture resulting from prior forming processes. In order to investigate the high temperature deformation behavio...Mechanical properties, corrosion behavior and hydrogen absorption of zirconium alloys are related to the texture resulting from prior forming processes. In order to investigate the high temperature deformation behavior of α-Zr, compression tests at 700 ℃, microstructure measurements via EBSD, and visco-plastic self-consistent modeling were performed. Twinning activity was negligible at strain rates ε≤1s^-1. The strain rate sensitivity m=0.17 seemed to be the same for all slip modes. Material parameters were fitted to reproduce the mechanical anisotropy and deformed texture, and were validated by comparing the simulated and measured strain anisotropy. The best-fit simulation showed that at high temperatures prismatic slip was the easiest deformation mode and pyramidal <c+a> was the hardest, but basal slip and pyramidal slip operated easily and in large amount.展开更多
基金the National Natural Science Foundation of China(Nos.U21A2051,52173297,52071133)the R&D Projects of Henan Academy of Sciences of China(No.220910009)+2 种基金the Key R&D and Promotion Projects of Henan Province of China(No.212102210441)the Joint Fund of Henan Science and Technology R&D Plan of China(No.222103810037)the Zhongyuan Scholar Workstation Funded Project of China(No.214400510028).
文摘A crystal plasticity finite element model was developed for the drawing deformation of pure copper micro wire,based on rate-dependent crystal plasticity theory.The impact of wire diameter compression ratio on the micro-mechanical deformation behavior during the wire drawing process was investigated.Results indicate that the internal deformation and slip of the drawn wire are unevenly distributed,forming distinct slip and non-slip zones.Additionally,horizontal strain concentration bands develop within the drawn wire.As the wire diameter compression ratio increases,the strength of the slip systems and the extent of slip zones inside the deformation zone also increase.However,the fluctuating stress state,induced by contact pressure and frictional stress,results in a rough and uneven wire surface and diminishes the stability of the drawing process.
基金This work was supported by the National Natural Science Foundation of China （No.20671027）, and the Natural Science Foundation of Anhui province, China （No.050440904）.
文摘Single-crystalline Ga-doped SnO2 nanowires and SnO2：Ga2O3 heterogeneous microcombs were synthesized by a simple one-step thermal evaporation and condensation method. They were characterized by means of X-ray powder diffraction （XRD）, field-emission scanning electron microscopy （FE-SEM）, energy-dispersive X-ray spectroscopy （EDS）, transmission electron microscopy （TEM） and selected-area electron diffraction （SAED）. FE-SEM images showed that the products consisted of nanowires and mierocombs that represent a novel morphology. XRD, SAED and EDS indicated that they were single-crystalline tetragonal SnO2. The influence of experimental conditions on the morphologies of the products is discussed. The morphology of the product showed a ribbon-like stem and nanoribbon array aligned evenly along one or both side of the nanoribbon. It was found that many Ga2O3 nanoparticles deposited on the surface of the microcombs. The major core nanoribbon grew mainly along the [110] direction and the self-organized branching nanoribbons grew epitaxially along [110] or [110] orientation from the （110） plane of the stem. A growth process was proposed for interpreting the growth of these remarkable SnO2：Ga2O3 heterogeneous microcombs. Due to the heavy doping of Ga, the emission peak in photoluminescence spectra has red-shifted as well as broadened significantly.
基金Projects(51531005,51421001,51371202,51505046)supported by the National Natural Science Foundation of ChinaProject(106112017CDJQJ138803)supported by the Fundamental Research Funds for the Central University of China
文摘Mechanical properties, corrosion behavior and hydrogen absorption of zirconium alloys are related to the texture resulting from prior forming processes. In order to investigate the high temperature deformation behavior of α-Zr, compression tests at 700 ℃, microstructure measurements via EBSD, and visco-plastic self-consistent modeling were performed. Twinning activity was negligible at strain rates ε≤1s^-1. The strain rate sensitivity m=0.17 seemed to be the same for all slip modes. Material parameters were fitted to reproduce the mechanical anisotropy and deformed texture, and were validated by comparing the simulated and measured strain anisotropy. The best-fit simulation showed that at high temperatures prismatic slip was the easiest deformation mode and pyramidal <c+a> was the hardest, but basal slip and pyramidal slip operated easily and in large amount.
