High-resolution transmission electron microscopy (HRTEM): Image processinganalysis of defects and grain boundaries in nanocrystalline materials

A brief overview of the application of the high resolution transmission ele ctron microscopy (HRTEM) method is given: the principle of HRTEM image form ation in an electron microscope; different modes of image formation; the ro le of contrast transfer function (CTF) in HRTEM image formation; definition and improvement of electron microscope resolution. As an example, the imag e processing of HRTEM micrographs of mechanically alloyed ZrO2-10mol% Y2O3 powders was performed in order to obtain information about alloying and tra nsformation at the atomic level. In this work the results obtained by applying the CRISP program to analyse the HRTEM photographs of mechanically alloyed nanocrystalline materials are presented. The investigation is focused on the following regions: a) the g rain boundary region; b) the region of stacking faults; c) the region of ov erlapping layers of zirconia and yttria. Fourier filtering revealed at the atomic level one possible sequence of all oying that occurred at the grain boundary, on the stacking faults and in th e overlapping layers. Performing the Fourier filtering with different filte ring mask, it was possible to isolate the separate planes introduced into t he correct order of particular family of m-ZrO2 lattice. The introduced pla nes belonging to m-ZrO2 lattice. Since they were identified in correspondin g FT, from which the filtering was performed, it was possible to give an in terpretation about the transformation due to the mechanical alloying observ ed in the particular HRTEM image.