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
In this study,the effect of hydrogen on dislocation and twinning behavior along various grain boundaries in a high-manganese twinning-induced plasticity steel was investigated using an in situ micropillar compression ...In this study,the effect of hydrogen on dislocation and twinning behavior along various grain boundaries in a high-manganese twinning-induced plasticity steel was investigated using an in situ micropillar compression test.The compressive stress in both elastic and plastic regimes was increased with the presence of hydrogen.Further investigation by transmission electron backscatter diffraction and scanning transmission electron microscope demonstrated that hydrogen promoted both dislocation multiplication and twin formation,which resulted in higher stress concentration at twin-twin and twin-grain boundary intersections.展开更多
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X.Lu and D.Wang acknowledge the financial support from the Research Council of Norway through the project MHEAT(294689)and HyLINE(294739)。
文摘In this study,the effect of hydrogen on dislocation and twinning behavior along various grain boundaries in a high-manganese twinning-induced plasticity steel was investigated using an in situ micropillar compression test.The compressive stress in both elastic and plastic regimes was increased with the presence of hydrogen.Further investigation by transmission electron backscatter diffraction and scanning transmission electron microscope demonstrated that hydrogen promoted both dislocation multiplication and twin formation,which resulted in higher stress concentration at twin-twin and twin-grain boundary intersections.
