Wu W, Schaeublin R
Laboratory for Nuclear Materials, Paul Scherrer Institute, Villigen PSI, Switzerland.
Institute of Advanced Structure & Technology, Beijing Institute of Technology, Beijing, China.
J Microsc. 2019 Jul;275(1):11-23. doi: 10.1111/jmi.12797. Epub 2019 May 8.
For end-on screw dislocations and inclined dislocations within thin transmission electron microscopy (TEM) foil, TEM diffraction contrast image is largely modified around piercing point due to free surface relaxation. Based on many-beam Schaeublin-Stadelmann equations, TEM diffraction contrast images simulation of inclined dislocations within thin pure Fe TEM foil are performed and the difference between isotropic and anisotropic dislocation models are studied. Image force are superposed onto bulk elastic field of dislocation in thin foil, the elastic distortions nearby the two emerging points of a straight inclined dislocation located in an elastically isotropic/anisotropic thin foil are expressed as semianalytical solution in Fourier space, and the semianalytical image stress solutions in Fourier space are implemented into CUFOUR for studying free surface relaxation effect on TEM diffraction contrast of dislocation. Simulation results suggest that the diffraction contrast at the ends of dislocation is modified drastically by image forces, and effects of anisotropy cannot be neglected. LAY DESCRIPTION: For end-on screw dislocations and inclined dislocations within thin transmission electron microscopy (TEM) foil, TEM diffraction contrast image is largely modified around piercing point due to free surface relaxation. Based on many-beam Schaeublin-Stadelmann equations, TEM diffraction contrast images simulation of inclined dislocations within thin pure Fe TEM foil are performed and the difference between isotropic and anisotropic dislocation models are studied. Image force are superposed onto bulk elastic field of dislocation in thin foil, the elastic distortions nearby the two emerging points of a straight inclined dislocation located in an elastically isotropic/anisotropic thin foil are expressed as semianalytical solution in Fourier space, and the semianalytical image stress solutions in Fourier space are implemented into CUFOUR for studying free surface relaxation effect on TEM diffraction contrast of dislocation. Simulation results suggest that the diffraction contrast at the ends of dislocation is modified drastically by image forces, and effects of anisotropy cannot be neglected.
对于薄透射电子显微镜（TEM）箔片中的端接螺旋位错和倾斜位错，由于自由表面弛豫，TEM衍射衬度图像在穿透点周围会发生很大改变。基于多束Schaublin-Stadelmann方程，对纯铁薄TEM箔片中倾斜位错的TEM衍射衬度图像进行了模拟，并研究了各向同性和各向异性位错模型之间的差异。像力叠加在薄箔中位错的体弹性场上，位于弹性各向同性/各向异性薄箔中的直倾斜位错的两个出射点附近的弹性畸变在傅里叶空间中表示为半解析解，并且将傅里叶空间中的半解析像应力解应用于CUFOUR中，以研究自由表面弛豫对位错TEM衍射衬度的影响。模拟结果表明，位错端部的衍射衬度会因像力而发生剧烈改变，各向异性的影响不可忽略。
对于薄透射电子显微镜（TEM）箔片中的端接螺旋位错和倾斜位错，由于自由表面弛豫，TEM衍射衬度图像在穿透点周围会发生很大改变。基于多束Schaublin-Stadelmann方程，对纯铁薄TEM箔片中倾斜位错的TEM衍射衬度图像进行了模拟，并研究了各向同性和各向异性位错模型之间的差异。像力叠加在薄箔中位错的体弹性场上，位于弹性各向同性/各向异性薄箔中的直倾斜位错的两个出射点附近的弹性畸变在傅里叶空间中表示为半解析解，并且将傅里叶空间中的半解析像应力解应用于CUFOUR中，以研究自由表面弛豫对位错TEM衍射衬度的影响。模拟结果表明，位错端部的衍射衬度会因像力而发生剧烈改变，各向异性的影响不可忽略。
