SEM Specimen Preparation by Broad Ion Beam Etching For Enhanced Channeling and Orientation Imaging

Abstract It is well known that the “channeling contrast” and EBSD pattern formation, which is the basis for “orientation imaging microscopy” (OIM), is highly sensitive to specimen surface quality in SEM studies. Typically, specimens for these studies are prepared by a combination of mechanical grinding then chemical etching or electropolishing. As an alternative to the chemical step(s) in this technique, we report a method based upon broad ion beam etching equipment [1]. This alternative method is more universal and reliable for enhanced channeling contrast and EBSD/OIM of metallic materials. A variety of polycrystalline metallic specimens were etched in an instrument dedicated for etching and coating SEM specimens [1] and examined in the SEM for channeling contrast and OIM mapping. Fig. la is a SEM image of an annealed titanium sheet specimen in as-received condition showing a well-defined surface texture. It can be seen that channeling contrast is absent, presumably due to the existence of a surface layer formed during the manufacturing process.