Argon bam cross sectioning

xamination of material cross sections often provides essential information about the crystal structure, layer or film thicknesses, existence of voids or cracks, and other properties that might impact performance and reliability. Many mechanical methods are available to prepare specimen cross sections for scanning electron microscope (SEM) observation, particularly for metallographic sample preparation. However, mechanical polishing presents several problems: • In composite materials with different hardness values, the polished surface becomes uneven as the softer components are cut faster and more easily than the harder components; • In soft materials, particles of hard abrasive can be buried in the material being polished; • In materials with voids, the edges of the voids can stretch and deform; • For metals, due to the strain caused by mechanical polishing on the polished surface, the information about the crystal structure by means of electron back-scatter diffraction (EBSD) can becomes difficult or impossible to see; • Fine features such as hairline cracks and small voids can get smeared shut and will not be recognized as such; and • Water-soluble phases are challenging to preserve, even with kerosene or oil instead of water. Microtome methods An ultra microtome and focused ion beam (FIB) are also often used to prepare cross sections of specimens. The ultra microtome is mainly for preparation of soft materials, such as biological and polymer specimens. Microtome preparation requires embedding of the sample with possible additional staining to reveal certain features or components; this is a lengthy procedure that requires a great deal of skill, and could sometimes lead to unforeseen artifacts in the resulting specimens. The FIB is a powerful tool when precise positioning of a cross section is required. However, the size of the resulting cross section is very limited, and use of heavy gallium ions can cause some damage to the sample surface. TECH SPOTLIGHT