Point-by-point compositional analysis for atom probe tomography

This new alternate approach to data processing for analyses that traditionally employed grid-based counting methods is necessary because it removes a user-imposed coordinate system that not only limits an analysis but also may introduce errors. We have modified the widely used ''binomial'' analysis for APT data by replacing grid-based counting with coordinate-independent nearest neighbour identification, improving the measurements and the statistics obtained, allowing quantitative analysis of smaller datasets, and datasets from non-dilute solid solutions. It also allows better visualisation of compositional fluctuations in the data. Our modifications include:. using spherical k-atom blocks identified by each detected atom's first k nearest neighbours. 3D data visualisation of block composition and nearest neighbour anisotropy. using z-statistics to directly compare experimental and expected composition curves. Similar modifications may be made to other grid-based counting analyses (contingency table, Langer-Bar-on-Miller, sinusoidal model) and could be instrumental in developing novel data visualisation options. Crown Copyright (C) 2014 Published by Elsevier B.V. This is an open access article under the CC BY license