The deformation microstructure evolution of single crystal copper wires produced by OCC method has been studied with the help of TEM, EBSD; OM. The results show that there are a small number of dendrites; twins in the...The deformation microstructure evolution of single crystal copper wires produced by OCC method has been studied with the help of TEM, EBSD; OM. The results show that there are a small number of dendrites; twins in the undeformed single crystal copper wires. However, it is difficult to observe these dendrites in deformed single crystal copper wires. The structure evolution of deformed single crystal copper wires during drawing process can be divided into three stages. When the true strain is lower than 0.94, macroscopic subdivision of grains is not evident,; the microscopic evolution of deformed structure is that the cells are formed; elongated in drawn direction. When the true strain is between 0.94; 1.96, macroscopic subdivision of grains takes place,; the number of microbands located on {111}; cell blocks is much more than that with the true strain lower than 0.94. When the true strain is larger than 1.96, the macroscopic subdivision of grains becomes more evident than that with the true strain between 0.94; 1.96,; S-bands structure; lamellar boundaries will be formed. From EBSD analysis, it is found that part of 100 texture resulting from solidifying is transformed into 111; 112 due to shear deformation, but 100 texture component is still kept in majority. When the true strain is 0.94, the misorientation angle of dislocation boundaries resulting from deformation is lower than 14°. However, when the true strain arrives at 1.96, the misorientation angle of some boundaries will be greater than 50°,; the peak of misorientation angle distribution produced by texture evolution is located in the range between 25°; 30°.展开更多
By using electron backscatter diffraction（EBSD） and transmission electron microscopy（TEM）, the effect of Si content on microstructure characteristics of three as-extruded Ale SieM g alloys was investigated. Result...By using electron backscatter diffraction（EBSD） and transmission electron microscopy（TEM）, the effect of Si content on microstructure characteristics of three as-extruded Ale SieM g alloys was investigated. Results showed that the density of coarse Si particles played a critical role in dynamic recrystallization. Dynamic recrystallization rarely occurred in S1 alloy with less Si content; however, it happened in the Si-rich zones in S2 alloy with a medium Si content. And a mature recrystallization was observed in S3 alloy with high Si content. Although deformation was carried out at high temperature, particle-stimulated dynamic recrystallization occurred in Si-rich zones.展开更多
The micro- and nanostructures of human dental enamel were investigated by transmission electron microscopy （TEM） and electron backscatter diffraction （EBSD）. For this purpose, TEM slices were prepared from teeth b...The micro- and nanostructures of human dental enamel were investigated by transmission electron microscopy （TEM） and electron backscatter diffraction （EBSD）. For this purpose, TEM slices were prepared from teeth by focused ion-beam milling. These slices enabled TEM and transmission-EBSD （t-EBSD） investigations to be performed, while standard EBSD on bulk tooth samples resulted only in Kikuchi patterns. On the TEM slices, t-EBSD enabled automated mapping. The TEM images and the EBSD data dearly elucidated the arrangement of the hydroxyapatite crystals on the nanometer scale. Information regarding the crystallographic orientation of the apatite grains enabled the deduction of novel nanotechnological building principles of the enamel structure based on a chain-like arrangement of the crystallites.展开更多
Hot compression test was carried out at 1000 ~C to investigate the dynamic recrys- tallization nucleation mechanism of a nickel-base superalloy. It was found that the bulging of original grain boundaries was inhibited...Hot compression test was carried out at 1000 ~C to investigate the dynamic recrys- tallization nucleation mechanism of a nickel-base superalloy. It was found that the bulging of original grain boundaries was inhibited by carbides and deformation twins at the boundaries. Recrystallized nuclei evolved from the subgrains of dislocation re- configuration along original grain boundaries, and the growth of the potential nuclei was carried out by the coalescence of subgrains. The necklace structure of recrys- tallized grains along original grain boundaries was attributed to the strain gradient from grain boundary to grain interior.展开更多
This study investigates the microstructure and local corrosion behavior of an Al-Mg-Si-Cu alloy,which has been subjected to cold-rolling with different deformation strain ratios(DSRs)and followed by artificial aging.A...This study investigates the microstructure and local corrosion behavior of an Al-Mg-Si-Cu alloy,which has been subjected to cold-rolling with different deformation strain ratios(DSRs)and followed by artificial aging.Accelerated corrosion tests show that peak-aged samples with a small DSR(5-10%)are sensitive to inter-granular corrosion(IGC)along both the normal and rolling directions.When the DSR increases to medium strength(20-40%),IGC sensitivity decreases along both directions and corrosion propagates anisotropically.When the DSR is 60-80%,IGC sensitivity along the normal direction continues to decrease,but increases along the rolling direction,indicating pronounced corrosion anisotropy.Microstructural characterization reveals the decreased IGC sensitivity is mainly attributed to a reduction in element segregation at high-angle grain boundaries and the kinked and discontinuous grain boundary corrosion paths.The increased IGC sensitivity along the rolling direction could be related to the significantly flattened grains.展开更多
基金Supported by the National Natural Science Foundation of China (Grant Nos. 50471098 and 59971033)the Natural Science Foundation of Shaanxi Province, China (Grant No. 2003E101)the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institution of MOE, China
文摘The deformation microstructure evolution of single crystal copper wires produced by OCC method has been studied with the help of TEM, EBSD; OM. The results show that there are a small number of dendrites; twins in the undeformed single crystal copper wires. However, it is difficult to observe these dendrites in deformed single crystal copper wires. The structure evolution of deformed single crystal copper wires during drawing process can be divided into three stages. When the true strain is lower than 0.94, macroscopic subdivision of grains is not evident,; the microscopic evolution of deformed structure is that the cells are formed; elongated in drawn direction. When the true strain is between 0.94; 1.96, macroscopic subdivision of grains takes place,; the number of microbands located on {111}; cell blocks is much more than that with the true strain lower than 0.94. When the true strain is larger than 1.96, the macroscopic subdivision of grains becomes more evident than that with the true strain between 0.94; 1.96,; S-bands structure; lamellar boundaries will be formed. From EBSD analysis, it is found that part of 100 texture resulting from solidifying is transformed into 111; 112 due to shear deformation, but 100 texture component is still kept in majority. When the true strain is 0.94, the misorientation angle of dislocation boundaries resulting from deformation is lower than 14°. However, when the true strain arrives at 1.96, the misorientation angle of some boundaries will be greater than 50°,; the peak of misorientation angle distribution produced by texture evolution is located in the range between 25°; 30°.
基金financially supported by the Jiangsu Graduated-student Innovation Program of China (CXZZ-0146)the Scientific Research Foundation of Graduate School of Southeast University (YBJJ1235)
文摘By using electron backscatter diffraction（EBSD） and transmission electron microscopy（TEM）, the effect of Si content on microstructure characteristics of three as-extruded Ale SieM g alloys was investigated. Results showed that the density of coarse Si particles played a critical role in dynamic recrystallization. Dynamic recrystallization rarely occurred in S1 alloy with less Si content; however, it happened in the Si-rich zones in S2 alloy with a medium Si content. And a mature recrystallization was observed in S3 alloy with high Si content. Although deformation was carried out at high temperature, particle-stimulated dynamic recrystallization occurred in Si-rich zones.
文摘The micro- and nanostructures of human dental enamel were investigated by transmission electron microscopy （TEM） and electron backscatter diffraction （EBSD）. For this purpose, TEM slices were prepared from teeth by focused ion-beam milling. These slices enabled TEM and transmission-EBSD （t-EBSD） investigations to be performed, while standard EBSD on bulk tooth samples resulted only in Kikuchi patterns. On the TEM slices, t-EBSD enabled automated mapping. The TEM images and the EBSD data dearly elucidated the arrangement of the hydroxyapatite crystals on the nanometer scale. Information regarding the crystallographic orientation of the apatite grains enabled the deduction of novel nanotechnological building principles of the enamel structure based on a chain-like arrangement of the crystallites.
基金supported by the National Basic Research Program of China (No.2010CB631203)the National Natural Science Foundation of China (No.50841025)
文摘Hot compression test was carried out at 1000 ~C to investigate the dynamic recrys- tallization nucleation mechanism of a nickel-base superalloy. It was found that the bulging of original grain boundaries was inhibited by carbides and deformation twins at the boundaries. Recrystallized nuclei evolved from the subgrains of dislocation re- configuration along original grain boundaries, and the growth of the potential nuclei was carried out by the coalescence of subgrains. The necklace structure of recrys- tallized grains along original grain boundaries was attributed to the strain gradient from grain boundary to grain interior.
基金supported by the National Natural Science Foundation of China(91960202,52171020,51701219)the CAS Project for Young Scientists in Basic Research(YSBR-025)+1 种基金the Youth Innovation Promotion Association CAS(2022188)the National Key R&D Program of China(2021YFC2800503 and 2022YFB3708300)。
基金supported by the National Natural Science Foundation of China(Nos.51831004,52001119,11427806,and 51671082)the National Key Research and Development Program of China(No.2016YFB0300801)the Fundamental Research Funds for the Central Universities。
文摘This study investigates the microstructure and local corrosion behavior of an Al-Mg-Si-Cu alloy,which has been subjected to cold-rolling with different deformation strain ratios(DSRs)and followed by artificial aging.Accelerated corrosion tests show that peak-aged samples with a small DSR(5-10%)are sensitive to inter-granular corrosion(IGC)along both the normal and rolling directions.When the DSR increases to medium strength(20-40%),IGC sensitivity decreases along both directions and corrosion propagates anisotropically.When the DSR is 60-80%,IGC sensitivity along the normal direction continues to decrease,but increases along the rolling direction,indicating pronounced corrosion anisotropy.Microstructural characterization reveals the decreased IGC sensitivity is mainly attributed to a reduction in element segregation at high-angle grain boundaries and the kinked and discontinuous grain boundary corrosion paths.The increased IGC sensitivity along the rolling direction could be related to the significantly flattened grains.
