Analytical electron microscopes are used in the microcharacterization of materials. The scanning electron microscope (SEM) makes possible the study of the fine structure of surfaces, while the transmission electron microscope (TEM) yields data about internal structure and composition. Each instrument may be used in multiple modes to result in different but complementary data from the same material.

MICROCHARACTERIZATION LAB I: SEM

SEM:
Click on the picture to see SEM micrographs of the surface of the broken ends of metal slugs of various compositions. The slugs were prepared during a lab session demonstrating mechanical properties of materials using the Instron to stretch the slugs to their breaking point. The SEM reveals that the materials have different microstructure that, in part, accounts for their different behavior under strain.

MICROCHARACTERIZATION LAB II: TEM and X-ray energy dispersive spectroscopy (EDS)

TEM:
Click on the picture to see TEM micrographs showing cross-sections of the fractured metals described above. The TEM yields brightfield images that show internal structures, darkfield images that indicate corresponding crystalline materials, diffraction patterns showing the arrangement of the crystal planes, and lattice images showing the spacing between the rows of atoms making up a crystalline material.

X-RAY EDS:
Click on the picture to see EDS spectra from the metal samples showing their elemental composition.

CROCIDOLITE ASBESTOS: A problem resolved by TEM and x-ray EDS.

Asbestos is a commonly-occurring environmental hazard. According to government regulations, both elemental and compositional analyses, at a level satisfied only by the use of TEM coupled with EDS, are mandated by law before an area may be declared environmentally safe from asbestos contamination. Click on the image to view examples of these complementary data types.