Convergent beam electron diffraction (CBED) was used to profile the thickness of aluminium alloys foils prepared by using the twinjet electropolishing method. The two-beam CBED condition was obtained by exciting the {200} and {111} aluminium diffracted g-vector. The aluminium alloy foil thicknesses were calculated at different distances from the sample hole edge. In areas where only one Kossel-Mӧllenstedt (K-M) minima fringe was obtained, the thickness was determined by matching the experimental with simulated convergent beam diffraction pattens. In areas far away from the sample edge, the thickness of foils was high enough to generate at least two (K-M) minima fringes, required for linear regression fitting.
Samples Being Thin Enough for Achieving Atomic Scale Magnification: To achieve highest possible magnification with the highest resolution and observe the nanometer-scale features of the microstructure in aluminum alloys, it is important to obtain samples which are as thin as we possibly can get to. The samples must be so thin that they can be transparent to the electron beam. To have a clear picture of how profile of a thin sample should look like, advanced microscopes were used where the electrons are concentrated in very narrow areas over the sample. The electron beam going through the sample, experiences a physic phenomenon known as diffraction, which is recorded below the sample, and thickness is calculated out of it. By concentrating the electron beam to different points over the sample, thickness profile was reconstructed. This is imperative for building up reference profiles for check and compare of samples used in transmission electron microscopy.