The micro orientation theological behavior of AZ61 Mg alloy during net-shape forming of tensile specimens via close-die pressing of extruded preformed and the effect of the press deformation rate on the microstructure...The micro orientation theological behavior of AZ61 Mg alloy during net-shape forming of tensile specimens via close-die pressing of extruded preformed and the effect of the press deformation rate on the microstructure characteristics were characterized with electron back-scattering diffraction(EBSD)orientation imaging microscopy and metallography.The results indicate that the intensity distribution of basal{0001}<1010>texture on the cross-section of the extruded perform is uniform and parallel to the extrusion direction.Subjected to pressing in extrusion direction,deformation shear stress leads to grain rotation and basal texture {0001}<1010>deviation from the extrusion direction,spreading in the direction perpendicular to pressing direction.The texture intensity increases with the press deformation rate and reaches its peak value at 50%,which is considerably lower than the value reached in extrusion deformation.Then,the texture intensity decreases with the press deformation rate reversely.展开更多
The meso-structure mineral composition and fracture mechanism of uniaxial compressed mudstone samples at high temperature were analyzed by XRD and scanning electron microscopy. The effect of tem- perature on mudstone ...The meso-structure mineral composition and fracture mechanism of uniaxial compressed mudstone samples at high temperature were analyzed by XRD and scanning electron microscopy. The effect of tem- perature on mudstone composition and fracture mechanism were studied from a meso-structural per- spective, and the relationship between meso-structure and macro-mechanical characteristics at high temperature was revealed. The findings demonstrated that the fluctuation in diffraction intensity of kao- linite in the mudstone caused the fluctuation in its mechanical properties. The overall structure under- went a phase change around 600℃, which led to the sudden change in the mechanical properties of mudstone samples. When the temperature reached 600 ℃, the crystalline state worsened and kaolinite disappeared; however, some illite was produced, indicating that the chemical reaction of the structure and sudden drop of bearing capacity of the mudstone. Mudst0ne fracturing at high temperature involves mainly intergranular and transgranular fractures, which are typical in micro-brittle tensile failure. Con- sidering the macro-fracture characteristics of mudstone, the results suggested that macro-fracture under external force corresoonds to the meso-fracture.展开更多
Zinc oxide（ZnO） microrod arrays were synthesized on Si substrate by a vapor phase transport（VPT） method in a tube furnace.The obtained ZnO microrods are characterized by scanning electron microscopy（SEM） and X-r...Zinc oxide（ZnO） microrod arrays were synthesized on Si substrate by a vapor phase transport（VPT） method in a tube furnace.The obtained ZnO microrods are characterized by scanning electron microscopy（SEM） and X-ray diffraction（XRD）.The photoluminescence（PL） measurement indicates that the ZnO microrods have a strong ultraviolet（UV） emission centered at ~391 nm and a defect-related emission centered at ~530 nm.After the microrods were coated with graphene oxide（GO）,the PL intensity of the hybrid microstructure is quenched compared with that of the bare one at the same excitation condition,and the PL intensity changes with the concentration of the GO.The fluorescence quenching mechanism is also discussed in this work.展开更多
基金Project(CSTC2007AA4008)supported by the Scientific and Technological Project in Chongqing of China
文摘The micro orientation theological behavior of AZ61 Mg alloy during net-shape forming of tensile specimens via close-die pressing of extruded preformed and the effect of the press deformation rate on the microstructure characteristics were characterized with electron back-scattering diffraction(EBSD)orientation imaging microscopy and metallography.The results indicate that the intensity distribution of basal{0001}<1010>texture on the cross-section of the extruded perform is uniform and parallel to the extrusion direction.Subjected to pressing in extrusion direction,deformation shear stress leads to grain rotation and basal texture {0001}<1010>deviation from the extrusion direction,spreading in the direction perpendicular to pressing direction.The texture intensity increases with the press deformation rate and reaches its peak value at 50%,which is considerably lower than the value reached in extrusion deformation.Then,the texture intensity decreases with the press deformation rate reversely.
基金financial support from the National Natural Science Foundation of China(Nos.51074166,51104128,51322401 and 51204159)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20120095110013)+1 种基金the Science and Technology Projects of Urban and Rural Housing Ministry of Construction of China(No.2011-k3-5)the‘‘Blue Project’’of Jiangsu Province are greatly appreciated
文摘The meso-structure mineral composition and fracture mechanism of uniaxial compressed mudstone samples at high temperature were analyzed by XRD and scanning electron microscopy. The effect of tem- perature on mudstone composition and fracture mechanism were studied from a meso-structural per- spective, and the relationship between meso-structure and macro-mechanical characteristics at high temperature was revealed. The findings demonstrated that the fluctuation in diffraction intensity of kao- linite in the mudstone caused the fluctuation in its mechanical properties. The overall structure under- went a phase change around 600℃, which led to the sudden change in the mechanical properties of mudstone samples. When the temperature reached 600 ℃, the crystalline state worsened and kaolinite disappeared; however, some illite was produced, indicating that the chemical reaction of the structure and sudden drop of bearing capacity of the mudstone. Mudst0ne fracturing at high temperature involves mainly intergranular and transgranular fractures, which are typical in micro-brittle tensile failure. Con- sidering the macro-fracture characteristics of mudstone, the results suggested that macro-fracture under external force corresoonds to the meso-fracture.
基金supported by the National Natural Science Foundation of China(Nos.1140428911404328 and 11547227)+1 种基金the Key Technologies R&D Program of Henan Province(No.142102210642)the High-level Talents Research and Startup Foundation Projects for Doctors of Zhoukou Normal University(No.ZKNU2015104)
文摘Zinc oxide（ZnO） microrod arrays were synthesized on Si substrate by a vapor phase transport（VPT） method in a tube furnace.The obtained ZnO microrods are characterized by scanning electron microscopy（SEM） and X-ray diffraction（XRD）.The photoluminescence（PL） measurement indicates that the ZnO microrods have a strong ultraviolet（UV） emission centered at ~391 nm and a defect-related emission centered at ~530 nm.After the microrods were coated with graphene oxide（GO）,the PL intensity of the hybrid microstructure is quenched compared with that of the bare one at the same excitation condition,and the PL intensity changes with the concentration of the GO.The fluorescence quenching mechanism is also discussed in this work.
