The anatomy of grain boundaries: Their structure and atomic-level solute distribution

The full macroscopic parameters of grain boundaries in a nanostructured ferritic alloy have been experimentally measured. A new atom-probe-tomography-based method determines the five degrees of freedom of the orientation relationship of the adjacent grains, and the local variations in the habit plane and solute excesses for tungsten and chromium across the grain boundary with a spatial resolution of up to 1 nm × 1 nm. The method also distinguishes ultrafine precipitates and ferrite–ferrite regions for a full description of the grain boundary.