Corrosion Investigation with Focused Ion Beam and SEM Technology

A strong relationship exists between the properties of the materials and the microstructure. Within the metals, small changes in the heat treatments, may significantly affect the microstructure. Consequently, the mechanical characteristics change. The microstructure also influence their corrosion behavior. The main diagnostic techniques allow the observation of surface events. Nonetheless, a simultaneous relation to the depth gives considerable information on the severity, the penetration and the extent of localized corrosion. Furthermore, the interaction between the metal surface and the main protection systems, such as coating, is a key issue to get durable structures. The focused ion beam FIB and SEM technology proved to be useful for the in-situ characterization of corrosion related issues. The FIB cross sections of pits, intermetallic particles and coatings give additional microstructural information on localized corrosion as well as on the coating / metal interface, which are not always evident to detect with conventional diagnostic techniques.