Scanning and transmission electron microscope investigation of preferential thinning during ion beam milling of an Al–Ag alloy containing γ precipitate plates and the subsequent effects on microanalysis

This paper demonstrates how a combination of high-resolution field-emission gun scanning and transmission electron microscope (TEM) techniques, including bright-field TEM imaging, two-detector secondary electron imaging, energy-dispersive X-ray spectroscopy (EDXS) and energy-filtering transmission electron microscopy (EFTEM), can be used to unambiguously determine the degree of preferential thinning during ion beam milling of an Al alloy containing thin plate-shaped precipitates, and illustrates the problems incurred by differential thinning of specimens on EDXS data and EFTEM images.