Electron Backscatter Diffraction(EBSD) has been used in conjunction with a Scanning Electron Microscope(SEM) combined with a focused ion beam(FIB) instrument to obtain three dimensional(3D) high resolution characteriz...Electron Backscatter Diffraction(EBSD) has been used in conjunction with a Scanning Electron Microscope(SEM) combined with a focused ion beam(FIB) instrument to obtain three dimensional(3D) high resolution characterizations of crystalline microstructures.This work reports on continued development that has proceeded on this technique.The technique is based on automated in-situ serial sectioning using the FIB and characterization of the sections using automated EBSD or orientation imaging microscopy(OIM).The technique extends the powerful features of two dimensional OIM into the third spatial dimension.This allows additional descriptive microstructural parameters to be obtained,for example the morphology and the crystallographic indices of interface planes.This paper provides an overview of the technique and shows results from two different samples: pearlite colonies in a high carbon steel and twin related grain triplets in a NiCo thin film.展开更多
The effect of grain size(in the range from 4 μm to 12 μm) on the hydrogen embrittlement(HE) of 304 austenitic stainless steel(ASS) was studied. HE susceptibility result shows that HE resistance increases with grain ...The effect of grain size(in the range from 4 μm to 12 μm) on the hydrogen embrittlement(HE) of 304 austenitic stainless steel(ASS) was studied. HE susceptibility result shows that HE resistance increases with grain refinement. Electron backscattered diffraction kernel average misorientation(EBSD-KAM)mapping shows that the strain localization can be mitigated by grain refinement. Hence, strain localization sites which act as highways for hydrogen diffusion and preferred crack initiation sites can be reduced along with grain refinement, leading to a high HE resistance. Meanwhile, grain size shows no influence on the strain induced martensite(SIM) transformation during the hydrogen charging slow strain tensile test(SSRT). Hence, the SIM formed during hydrogen charging SSRT is not responsible for the different HE resistance of 304 ASSs with various grain sizes. Hydrogen diffusion is supposed to be controlled by a competition between short-circuit diffusion along random grain boundary(RGB) and hydrogen trapping at dislocations, leading to a maximum hydrogen diffusion coefficient in the 304 ASS with an average grain size of 8 μm.展开更多
An increasing {110} orientation degree behavior was observed during etching of chemical vapor deposition （CVD） diamond films by partially melting Ce-7%Fe alloys. In order to accurately investigate this phenomenon, t...An increasing {110} orientation degree behavior was observed during etching of chemical vapor deposition （CVD） diamond films by partially melting Ce-7%Fe alloys. In order to accurately investigate this phenomenon, the X-ray diffraction method was used to identify the changes in the surface crystal orientation of the diamond films etched by Ce-7%Fe alloys, and evolution of orientation along the growth direction of the un-etched diamond film was analyzed by electron backscattering diffraction （EBSD）, and then the morphology of etched diamond surface was observed by scanning electron microscopy （SEM）. The results showed that the {110 } orientation degree of diamond surface increased due to the anisotropy in diamond etching with Ce-7%Fe, which was verified by the etching ＂pit＂ in SEM micrographs.展开更多
文摘Electron Backscatter Diffraction(EBSD) has been used in conjunction with a Scanning Electron Microscope(SEM) combined with a focused ion beam(FIB) instrument to obtain three dimensional(3D) high resolution characterizations of crystalline microstructures.This work reports on continued development that has proceeded on this technique.The technique is based on automated in-situ serial sectioning using the FIB and characterization of the sections using automated EBSD or orientation imaging microscopy(OIM).The technique extends the powerful features of two dimensional OIM into the third spatial dimension.This allows additional descriptive microstructural parameters to be obtained,for example the morphology and the crystallographic indices of interface planes.This paper provides an overview of the technique and shows results from two different samples: pearlite colonies in a high carbon steel and twin related grain triplets in a NiCo thin film.
基金financially supported by the National Natural Science Foundation of China (No. U1608257)
文摘The effect of grain size(in the range from 4 μm to 12 μm) on the hydrogen embrittlement(HE) of 304 austenitic stainless steel(ASS) was studied. HE susceptibility result shows that HE resistance increases with grain refinement. Electron backscattered diffraction kernel average misorientation(EBSD-KAM)mapping shows that the strain localization can be mitigated by grain refinement. Hence, strain localization sites which act as highways for hydrogen diffusion and preferred crack initiation sites can be reduced along with grain refinement, leading to a high HE resistance. Meanwhile, grain size shows no influence on the strain induced martensite(SIM) transformation during the hydrogen charging slow strain tensile test(SSRT). Hence, the SIM formed during hydrogen charging SSRT is not responsible for the different HE resistance of 304 ASSs with various grain sizes. Hydrogen diffusion is supposed to be controlled by a competition between short-circuit diffusion along random grain boundary(RGB) and hydrogen trapping at dislocations, leading to a maximum hydrogen diffusion coefficient in the 304 ASS with an average grain size of 8 μm.
基金Project supported by the Fundamental Research Fund for the Central Universities (YWF-10-B01)
文摘An increasing {110} orientation degree behavior was observed during etching of chemical vapor deposition （CVD） diamond films by partially melting Ce-7%Fe alloys. In order to accurately investigate this phenomenon, the X-ray diffraction method was used to identify the changes in the surface crystal orientation of the diamond films etched by Ce-7%Fe alloys, and evolution of orientation along the growth direction of the un-etched diamond film was analyzed by electron backscattering diffraction （EBSD）, and then the morphology of etched diamond surface was observed by scanning electron microscopy （SEM）. The results showed that the {110 } orientation degree of diamond surface increased due to the anisotropy in diamond etching with Ce-7%Fe, which was verified by the etching ＂pit＂ in SEM micrographs.
