Diffraction contrast images of small stacking fault tetrahedra in f.c.c. metals

Abstract

Abstract Transmission electron microscopy images of stacking fault tetrahedra (SFTs) are studied in detail both experimentally and by image simulation. Experimental dark-field diffraction contrast images of SFTs are examined under various conditions. The image contrast of stacking faults and stair-rod dislocations are simulated based on standard multi-beam dynamical theory, and the image contrast of very small SFTs (< 2.6 nm) is calculated by the multi-slice method. The correspondence between experimental and calculated results under systematically varied conditions is quite satisfactory. Stacking faults make a larger contribution to the total SFT image than stair-rod dislocations. The images are generally smaller than the SFT. The difference in size depends on many parameters such as deviation from the Bragg condition, location in the foil, and specimen thickness. However, the difference is always smaller than the fringe spacing in the stacking fault image, and is generally smaller at a larger deviation ...