  Interfaces play critical roles in materials, and are usually both
structurally and compositionally complex microstructural features. The precise
characterization of their nature in three-dimensions at the atomic-scale is one
of the grand challenges for microscopy and microanalysis, as this information
is crucial to establish structure-property relationships. Atom probe tomography
is well-suited to analyzing the chemistry of interfaces at the nanoscale.
However, optimizing such microanalysis of interfaces requires great care in the
implementation across all aspects of the technique, from specimen preparation
to data analysis and ultimately the interpretation this information. This
article provides critical perspectives on key aspects pertaining to spatial
resolution limits and the issues with compositional analysis that can limit the
quantification of interface measurements. Here, we use the example of grain
boundaries in steels, however the results are applicable for the
characterization of grain boundaries and transformation interfaces in a very
wide range of industrially relevant engineering materials.
