Measuring grain-boundary segregation in nanocrystalline alloys: direct validation of statistical techniques using atom probe tomography

Atom probe tomography (APT) is used to investigate grain-boundary segregation of W solute atoms in nanocrystalline Ni. For the heat-treated specimens used here, the grain structure can be observed in the APT data, enabling direct composition analyses across individual grain boundaries. These direct measurements are used to validate methods proposed in earlier work, which determine the average segregation state in nanocrystalline materials through statistical analysis of the solute distribution, without knowledge of the boundary positions. Good agreement is demonstrated between the two experimental techniques.