Tomographic Atom Probe
	Atom probe tomography (APT) is an ultra high resolution microanalytical technique for the characterization of compositional variations in materials on the atomic and nanometer scale. This tomographic technique produces three-dimensional images of the internal structure of metals and semiconductors by the reconstruction of thousands of two-dimensional slices each containing a few atoms.  The resulting data are the spatial coordinates and the mass-to-charge ratios and hence the elemental identities of the atoms in the sampled volume.  Approximately a million  to 3 million  atoms are obtained in each experiment. These data may be visualized by a variety of representations including three dimensional atom maps, isoconcentration surfaces, two-dimensional composition slices and concentration profiles. The atom-by-atom data may also be statistically analyzed to provide unique characterization of the solute distribution in the material, solute segregation and the partitioning of atoms into different phases. Atom probe tomography has been applied to many areas of material science including phase transformations, solute clustering, ordering, radiation damage, superalloys, intermetallics, bulk metallic glasses, thin films and alloy design.