Figure 1. a: Nanocrystalline Al–0.5Ag atom probe reconstruction. b: Approximately one million atom slice from the region of interest marked in (a) showing grain boundary and indexed pole information in each grain. c–f: The plane orientation extraction and spatial dis- tribution map results from each indexed pole.
planes detected within these pole regions of the reconstruc- tion (Fig. 1c–1f). The algorithm works by producing a 1D spatial distribution map (SDM) along a range of different directions in 3D. A 1D SDM is a histogram of atomic dis- tances along a particular directional component, within a given region of interest (ROI). A fast Fourier transform (FFT) is then applied to each SDM and the signal intensity is plotted over the range of directions, expressed in polar angles. The highest signal corresponds to the normal to the sets of detected planes. A clear maximum could be observed for all families of planes. Finally, the SDMs corresponding to the maximums in each pole region are provided, the
peak-to-peak distance of which should be close to the actual plane spacings in the analyzed sample. This information can then be used to determine the
orientation of each grain relative to the detector and further, the misorientation between each of the grains. The polar angles can be converted to Cartesian unit vectors within the specimen frame using the following sets of equations:
