In this paper, the orange peel defect in the surface range of the st14 steel sheet has been investigated using the electron backscattered diffraction (EBSD) technique. It has been found that the orange peel defect in ...In this paper, the orange peel defect in the surface range of the st14 steel sheet has been investigated using the electron backscattered diffraction (EBSD) technique. It has been found that the orange peel defect in the st14 steel sheet was resulted from the local coarse grains which were produced during hot-rolling due to the critical deformation in dual-phase zone. During deep drawing, the coarse grains with {100}<001> microtexture can slip on the {112}<111> slip system to form bulging and yields orange peel defects, while the coarse grains with {112}<110> orientation do not form the defect as the Schmid factor of {112}<111> slip system in it equals zero.展开更多
We present a coaxial detection of the backscattered electrons in SEM. The lens-aperture has been used to filter in energy and focus the backscattered electrons. This particular geometry allows us to eliminate the low ...We present a coaxial detection of the backscattered electrons in SEM. The lens-aperture has been used to filter in energy and focus the backscattered electrons. This particular geometry allows us to eliminate the low energy backscattered electrons and collect the backscattered electrons, which are backscattered close to the incident beam orientation. The main advantage of this geometry is adapted to topographic contrast attenuation and atomic number contrast enhancement. Thus this new SEM is very suitable to analyze the material composition.展开更多
A new parallel Monte Carlo simulation method of secondary electron (SE) and back scattered electron images (BSE) of scanning electron microscopy (SEM) for a com plex geometric structure has been developed. This paper ...A new parallel Monte Carlo simulation method of secondary electron (SE) and back scattered electron images (BSE) of scanning electron microscopy (SEM) for a com plex geometric structure has been developed. This paper describes briefly the si mulation method and the modification to the conventional sampling method for the step length. Example simulation results have been obtained for several artifici al structures.展开更多
The Ni samples were electroformed from additive-free(AF) and saccharin-containing(SC) sulfamate solutions, respectively. In situ backscattered electron(BSE) imaging, electron backscatter diffraction(EBSD), and electro...The Ni samples were electroformed from additive-free(AF) and saccharin-containing(SC) sulfamate solutions, respectively. In situ backscattered electron(BSE) imaging, electron backscatter diffraction(EBSD), and electron-probe microanalysis(EPMA) were used to investigate the effect of annealing on the deformation behaviors of the AF and SC samples. The results indicate that columnar grains of the as-deposited AF sample had an approximated average width of 3 μm and an approximated aspect ratio of 8. The average width of columnar grains of the as-deposited SC sample was reduced to approximately 400 nm by the addition of saccharin to the electrolyte. A few very-large grains distributed in the matrix of the SC sample after annealing. No direct evidence indicated that S segregated at the grain boundaries before or after annealing. The average value of the total elongations of the SC samples decreased from 16% to 6% after annealing, whereas that of the AF samples increased from 18% to 50%. The dislocation recovery in grain-boundary areas of the annealed AF sample was reduced, which contributed to the appearance of microvoids at the triple junctions. The incompatibility deformation between very-large grains and fine grains contributed to the brittle fracture behavior of the annealed SC Ni.展开更多
The full energy distribution of backscattered electrons from the elastic peak do wn to the true-secondary electron peak for heavy metals, Ta, W, Pt and Au, in Au ger electron spectroscopy in the EN(E) mode has been st...The full energy distribution of backscattered electrons from the elastic peak do wn to the true-secondary electron peak for heavy metals, Ta, W, Pt and Au, in Au ger electron spectroscopy in the EN(E) mode has been studied with a Monte Carlo simulation method, which includes cascade-secondary-electron production. The sim ulation model is based on the use of a dielectric function for describing inelas tic scattering and secondary excitation, and on the use of Mott cross sections f or elastic scattering. A systematic comparison between the calculated and experi mental spectra measured with a cylindrical mirror analyzer has been made for pri mary energies ranging from 1 to 5keV. Excellent agreement was obtained for these heavy metals on the backscattering background at primary energies in the keV re gion. A significant contribution of cascade secondary electrons to the measured spectra on the low-energy side was found.展开更多
Prticle-in-cell（PIC） simulations demonstrated that,when the relativistic magnetron with diffraction output（MDO） is applied with a 410 kV voltage pulse,or when the relativistic magnetron with radial output is appli...Prticle-in-cell（PIC） simulations demonstrated that,when the relativistic magnetron with diffraction output（MDO） is applied with a 410 kV voltage pulse,or when the relativistic magnetron with radial output is applied with a 350 kV voltage pulse,electrons emitted from the cathode with high energy will strike the anode block wall.The emitted secondary electrons and backscattered electrons affect the interaction between electrons and RF fields induced by the operating modes,which decreases the output power in the radial output relativistic magnetron by about 15%（10%for the axial output relativistic magnetron）,decreases the anode current by about 5%（5%for the axial output relativistic magnetron）,and leads to a decrease of electronic efficiency by 8%（6%for the axial output relativistic magnetron）.The peak value of the current formed by secondary and backscattered current equals nearly half of the amplitude of the anode current,which may help the growth of parasitic modes when the applied magnetic field is near the critical magnetic field separating neighboring modes.Thus,mode competition becomes more serious.展开更多
The Al-Si-Mg alloy which can be strengthened by heat treatment is widely applied to the key components of aerospace and aeronautics. Iron-rich intermetallic compounds are well known to be strongly influential on mecha...The Al-Si-Mg alloy which can be strengthened by heat treatment is widely applied to the key components of aerospace and aeronautics. Iron-rich intermetallic compounds are well known to be strongly influential on mechanical properties in Al-Si-Mg alloys. But intermetallic compounds in cast Al-Si-Mg alloy intermetallics are often misidentified in previous metallurgical studies. It was described as many different compounds, such as AlFeSi, Al8Fe2Si, Al5（Fe, Mn）3Si2 and so on. For the purpose of solving this problem, the intermetallic compounds in cast Al-Si alloys containing 0.5% Mg were investigated in this study. The iron-rich compounds in Al-Si-Mg casting alloys were characterized by optical microscope（OM）, scanning electron microscope（SEM）, energy dispersive X-ray spectrometer（EDS）, electron backscatter diffraction（EBSD） and X-ray powder diffraction（XRD）. The electron backscatter diffraction patterns were used to assess the crystallographic characteristics of intermetallic compounds. The compound which contains Fe/Mg-rich particles with coarse morphologies was Al8FeMg3Si6 in the alloy by using EBSD. The compound belongs to hexagonal system, space group P6_2m, with the lattice parameter a=0.662 nm, c=0.792 nm. The β-phase is indexed as tetragonal Al3FeSi2, space group I4/mcm, a=0.607 nm and c=0.950 nm. The XRD data indicate that Al8FeMg3Si6 and Al3FeSi2 are present in the microstructure of Al-7Si-Mg alloy, which confirms the identification result of EBSD. The present study identified the iron-rich compound in Al-Si-Mg alloy, which provides a reliable method to identify the intermetallic compounds in short time in Al-Si-Mg alloy. Study results are helpful for identification of complex compounds in alloys.展开更多
A three-dimensional heat flux model for deep-penetrating electron beam welding(EBW)is established to mathematically describe the physical heat generation process during interaction between electrons and the dynamic mo...A three-dimensional heat flux model for deep-penetrating electron beam welding(EBW)is established to mathematically describe the physical heat generation process during interaction between electrons and the dynamic molten pool free surface.Monte Carlo method is used to determine the electron-target interaction,and random distribution of initial electrons,progressive trajectory tracing and electron backscattering models are used to describe the spatial distribution of electrons absorption.The model is verified in preset keyholes and applied in the simulation on electron beam welding process,and the calculated bead shape shows a good consistency with experimental results.展开更多
By using the Monte Carlo method, we simulated the trajectories of coaxial backscattering electrons corresponding to a new type of scanning electron microscope. From the calculated results, we obtain a universal expres...By using the Monte Carlo method, we simulated the trajectories of coaxial backscattering electrons corresponding to a new type of scanning electron microscope. From the calculated results, we obtain a universal expression, which describes with good accuracy the backscattering coefficient versus film thickness under all conditions used. By measuring the coaxial backscattering coefficient and using this universal formula, the thickness of thin films can be determined if the composition is known.展开更多
In this study,we explored the deformation mechanisms of Mg single crystals using a combination of scanning electron microscopy and electron backscattered diffraction in conjunction with a dedicated four-point bending ...In this study,we explored the deformation mechanisms of Mg single crystals using a combination of scanning electron microscopy and electron backscattered diffraction in conjunction with a dedicated four-point bending tester.We prepared two single-crystal samples,oriented along the<1120>and<1010>directions,to assess the mechanisms of deformation when the initial basal slip was suppressed.In the<1120>sample,the primary{1012}twin(T1)was confirmed along the<1120>direction of the sample on the compression side with an increase in bending stress.In the<1010>sample,T1 and the secondary twin(T2)were confirmed to be along the<1120>direction,with an orientation of±60°with respect to the bending stress direction,and their direction matched with(0001)in T1 and T2.This result implies that crystallographically,the basal slip occurs readily.In addition,the<1010>sample showed the double twin in T1 on the compression side and the tertiary twin along the<1010>direction on the tension side.These results demonstrated that the maximum bending stress and displacement changed significantly under the bend loading because the deformation mechanisms were different for these single crystals.Therefore,the correlation between bending behavior and twin orientation was determined,which would be helpful for optimizing the bending properties of Mg-based materials.展开更多
Using a scanning electron microscope (SEM) in the back-scattered electron (BSE) mode the composition of multi-element specimens may be determined based on the strong dependence of emission coefficient η on the averag...Using a scanning electron microscope (SEM) in the back-scattered electron (BSE) mode the composition of multi-element specimens may be determined based on the strong dependence of emission coefficient η on the average atomic number of elements Z. The output video signal of the usual BSE detectors is produced from their sensors, and the larger proportion of high-energy electrons with modified spectrum is added. Since η = is/ip (is and ip currents of specimen and probe), better accuracy must be achieved by direct measurements those currents on the specimen surface. Here, an experimental model of a current detector for a presented specimen is described. The cage is mounted on the carousel of the moving specimen stage. The input of the preamplifier is connected to the specimen holder in the form of a disk, the diameter of which is 12 mm. When the probe along its surface scanned, the input potential begins to pulsate with a negative polarity. The output of this preamplifier is connected to a small light-emitting diode, which creates intensity-modulated radiation in the chamber. Thus created the light video signal will be picked up by the photomultiplier of the E-T detector. The modes of true SE and BSE are set by applying tens bias volts of various polarities to the specimens or the cage itself.展开更多
基金This work was supported by the National Natural Science Foundation of China under grant No.50171040.
文摘In this paper, the orange peel defect in the surface range of the st14 steel sheet has been investigated using the electron backscattered diffraction (EBSD) technique. It has been found that the orange peel defect in the st14 steel sheet was resulted from the local coarse grains which were produced during hot-rolling due to the critical deformation in dual-phase zone. During deep drawing, the coarse grains with {100}<001> microtexture can slip on the {112}<111> slip system to form bulging and yields orange peel defects, while the coarse grains with {112}<110> orientation do not form the defect as the Schmid factor of {112}<111> slip system in it equals zero.
基金the National Natural Science Foundation of China!10045001
文摘We present a coaxial detection of the backscattered electrons in SEM. The lens-aperture has been used to filter in energy and focus the backscattered electrons. This particular geometry allows us to eliminate the low energy backscattered electrons and collect the backscattered electrons, which are backscattered close to the incident beam orientation. The main advantage of this geometry is adapted to topographic contrast attenuation and atomic number contrast enhancement. Thus this new SEM is very suitable to analyze the material composition.
基金This work wus supporeal by the National Naturul Science Foundation of China(No.10025420 and No.90206009).
文摘A new parallel Monte Carlo simulation method of secondary electron (SE) and back scattered electron images (BSE) of scanning electron microscopy (SEM) for a com plex geometric structure has been developed. This paper describes briefly the si mulation method and the modification to the conventional sampling method for the step length. Example simulation results have been obtained for several artifici al structures.
基金financially supported by the China Scholarship Council(No.201606460015)the support of the H.Nakano laboratory of Kyushu University for the study
文摘The Ni samples were electroformed from additive-free(AF) and saccharin-containing(SC) sulfamate solutions, respectively. In situ backscattered electron(BSE) imaging, electron backscatter diffraction(EBSD), and electron-probe microanalysis(EPMA) were used to investigate the effect of annealing on the deformation behaviors of the AF and SC samples. The results indicate that columnar grains of the as-deposited AF sample had an approximated average width of 3 μm and an approximated aspect ratio of 8. The average width of columnar grains of the as-deposited SC sample was reduced to approximately 400 nm by the addition of saccharin to the electrolyte. A few very-large grains distributed in the matrix of the SC sample after annealing. No direct evidence indicated that S segregated at the grain boundaries before or after annealing. The average value of the total elongations of the SC samples decreased from 16% to 6% after annealing, whereas that of the AF samples increased from 18% to 50%. The dislocation recovery in grain-boundary areas of the annealed AF sample was reduced, which contributed to the appearance of microvoids at the triple junctions. The incompatibility deformation between very-large grains and fine grains contributed to the brittle fracture behavior of the annealed SC Ni.
基金This work was supported by the National Natural Science Foundation of China(No.10025420 and No.90206009).
文摘The full energy distribution of backscattered electrons from the elastic peak do wn to the true-secondary electron peak for heavy metals, Ta, W, Pt and Au, in Au ger electron spectroscopy in the EN(E) mode has been studied with a Monte Carlo simulation method, which includes cascade-secondary-electron production. The sim ulation model is based on the use of a dielectric function for describing inelas tic scattering and secondary excitation, and on the use of Mott cross sections f or elastic scattering. A systematic comparison between the calculated and experi mental spectra measured with a cylindrical mirror analyzer has been made for pri mary energies ranging from 1 to 5keV. Excellent agreement was obtained for these heavy metals on the backscattering background at primary energies in the keV re gion. A significant contribution of cascade secondary electrons to the measured spectra on the low-energy side was found.
基金supported by National Natural Science Foundation of China(No.61302010)the Foundation of Science and Technology on High Power Microwave Laboratory,Central University Foundation(2013KW07)Work at the University of New Mexico in USA was supportedby ONR Grant N00014-13-1-0565
文摘Prticle-in-cell（PIC） simulations demonstrated that,when the relativistic magnetron with diffraction output（MDO） is applied with a 410 kV voltage pulse,or when the relativistic magnetron with radial output is applied with a 350 kV voltage pulse,electrons emitted from the cathode with high energy will strike the anode block wall.The emitted secondary electrons and backscattered electrons affect the interaction between electrons and RF fields induced by the operating modes,which decreases the output power in the radial output relativistic magnetron by about 15%（10%for the axial output relativistic magnetron）,decreases the anode current by about 5%（5%for the axial output relativistic magnetron）,and leads to a decrease of electronic efficiency by 8%（6%for the axial output relativistic magnetron）.The peak value of the current formed by secondary and backscattered current equals nearly half of the amplitude of the anode current,which may help the growth of parasitic modes when the applied magnetic field is near the critical magnetic field separating neighboring modes.Thus,mode competition becomes more serious.
基金supported by National Natural Science Foundation of China (Grant No. 50864002)Guangxi Provincial Natural Science Foundation of China (Grant No. 0991001)
文摘The Al-Si-Mg alloy which can be strengthened by heat treatment is widely applied to the key components of aerospace and aeronautics. Iron-rich intermetallic compounds are well known to be strongly influential on mechanical properties in Al-Si-Mg alloys. But intermetallic compounds in cast Al-Si-Mg alloy intermetallics are often misidentified in previous metallurgical studies. It was described as many different compounds, such as AlFeSi, Al8Fe2Si, Al5（Fe, Mn）3Si2 and so on. For the purpose of solving this problem, the intermetallic compounds in cast Al-Si alloys containing 0.5% Mg were investigated in this study. The iron-rich compounds in Al-Si-Mg casting alloys were characterized by optical microscope（OM）, scanning electron microscope（SEM）, energy dispersive X-ray spectrometer（EDS）, electron backscatter diffraction（EBSD） and X-ray powder diffraction（XRD）. The electron backscatter diffraction patterns were used to assess the crystallographic characteristics of intermetallic compounds. The compound which contains Fe/Mg-rich particles with coarse morphologies was Al8FeMg3Si6 in the alloy by using EBSD. The compound belongs to hexagonal system, space group P6_2m, with the lattice parameter a=0.662 nm, c=0.792 nm. The β-phase is indexed as tetragonal Al3FeSi2, space group I4/mcm, a=0.607 nm and c=0.950 nm. The XRD data indicate that Al8FeMg3Si6 and Al3FeSi2 are present in the microstructure of Al-7Si-Mg alloy, which confirms the identification result of EBSD. The present study identified the iron-rich compound in Al-Si-Mg alloy, which provides a reliable method to identify the intermetallic compounds in short time in Al-Si-Mg alloy. Study results are helpful for identification of complex compounds in alloys.
文摘A three-dimensional heat flux model for deep-penetrating electron beam welding(EBW)is established to mathematically describe the physical heat generation process during interaction between electrons and the dynamic molten pool free surface.Monte Carlo method is used to determine the electron-target interaction,and random distribution of initial electrons,progressive trajectory tracing and electron backscattering models are used to describe the spatial distribution of electrons absorption.The model is verified in preset keyholes and applied in the simulation on electron beam welding process,and the calculated bead shape shows a good consistency with experimental results.
文摘By using the Monte Carlo method, we simulated the trajectories of coaxial backscattering electrons corresponding to a new type of scanning electron microscope. From the calculated results, we obtain a universal expression, which describes with good accuracy the backscattering coefficient versus film thickness under all conditions used. By measuring the coaxial backscattering coefficient and using this universal formula, the thickness of thin films can be determined if the composition is known.
基金Project(51975167) supported by the National Natural Science Foundation,ChinaProject(2022ZX01A01) supported by the Key R&D Program in Heilongjiang Province,China。
基金supported by The AMADA FOUNDATION[grant number AF-2022030-B3]JSPS KAKENHI[grant numbers JP16K05961 and JP19K04065]。
文摘In this study,we explored the deformation mechanisms of Mg single crystals using a combination of scanning electron microscopy and electron backscattered diffraction in conjunction with a dedicated four-point bending tester.We prepared two single-crystal samples,oriented along the<1120>and<1010>directions,to assess the mechanisms of deformation when the initial basal slip was suppressed.In the<1120>sample,the primary{1012}twin(T1)was confirmed along the<1120>direction of the sample on the compression side with an increase in bending stress.In the<1010>sample,T1 and the secondary twin(T2)were confirmed to be along the<1120>direction,with an orientation of±60°with respect to the bending stress direction,and their direction matched with(0001)in T1 and T2.This result implies that crystallographically,the basal slip occurs readily.In addition,the<1010>sample showed the double twin in T1 on the compression side and the tertiary twin along the<1010>direction on the tension side.These results demonstrated that the maximum bending stress and displacement changed significantly under the bend loading because the deformation mechanisms were different for these single crystals.Therefore,the correlation between bending behavior and twin orientation was determined,which would be helpful for optimizing the bending properties of Mg-based materials.
文摘Using a scanning electron microscope (SEM) in the back-scattered electron (BSE) mode the composition of multi-element specimens may be determined based on the strong dependence of emission coefficient η on the average atomic number of elements Z. The output video signal of the usual BSE detectors is produced from their sensors, and the larger proportion of high-energy electrons with modified spectrum is added. Since η = is/ip (is and ip currents of specimen and probe), better accuracy must be achieved by direct measurements those currents on the specimen surface. Here, an experimental model of a current detector for a presented specimen is described. The cage is mounted on the carousel of the moving specimen stage. The input of the preamplifier is connected to the specimen holder in the form of a disk, the diameter of which is 12 mm. When the probe along its surface scanned, the input potential begins to pulsate with a negative polarity. The output of this preamplifier is connected to a small light-emitting diode, which creates intensity-modulated radiation in the chamber. Thus created the light video signal will be picked up by the photomultiplier of the E-T detector. The modes of true SE and BSE are set by applying tens bias volts of various polarities to the specimens or the cage itself.
