Microscopy Techniques to Analyse the Characteristics of the Metallic Materials
Microscopy techniques are powerful tool to evaluate the characteristics of the metallic alloys, as microstructure, chemical composition and crystalline orientation. Optical Microscopy (OM) is technique that allows analysing the microstructure and crystalline orientation of these materials. This microscopy technique is characterised by fast processing, low cost and being non-destructive. The imagines of OM are obtained via the light reflexion or transmitting with the material. Although optical microscopy is an excellent analysis technique, it presents certain limitations, as the inability to determine the chemical composition of material. Scanning Electron Microscopy (SEM) can rapidly analyse the microstructure and the chemical composition of the metallic alloys with a high resolution. SEM uses accelerated electrons to get pictures of the metallic materials features. Accelerate electrons interact with the atoms and electrons from surface layers of the material, which generates diverse types of the electrons and radiations. According to the type of electrons or radiation, different kinds of the materials characteristics can be seen. This technique provides good imagens of the characteristics of the material without producing damage, though the crystalline orientation is non-determinable via SEM. For this reason, both analysis techniques are complementary. Although OM and SEM are important tools to evaluate the metallic alloys, these materials must be pre-treated to be able to be characterised. The pre-treatment comprises of a mirror-to-polish and subsequent, etching process that defines the type of visible characteristics of metallic materials. In this chapter, the pre-treatment, OM and SEM to analyse the characteristics of the metallic alloys will be discussed.