Abstract
Boosting is a family of supervised learning algorithm that convert a set of weak learners into a single strong one. It is popular in the field of object tracking, where its main purpose is to extract the position, motion, and trajectory from various features of interest within a sequence of video frames. A scientific application explored in this study is to combine the boosting tracker and the Hough transformation, followed by principal component analysis, to extract the location and trace of grain boundaries within atom probe data. Before the implementation of this method, these information could only be extracted manually, which is time-consuming and error-prone. The effectiveness of this method is demonstrated on an experimental dataset obtained from a pure aluminum bi-crystal and validated on simulated data. The information gained from this method can be combined with crystallographic information directly contained within the data, to fully define the grain boundary character to its 5 degrees of freedom at near-atomic resolution in three dimensions. It also enables local atomic compositional and geometric information, i.e. curvature, to be extracted directly at the interface.
Highlights
Atom probe tomography (APT) is a microscopy and microanalysis technique that maps the position of millions of atoms from a material in three-dimensions with subnanometer spatial resolution
The technique relies on the effect of intense electric fields to cause the desorption and ionization of the atoms that constitute the surface of a sharp, needle-shaped specimen
The Al3+ peak, which is a sign that the electric field is locally slightly less elevated, often correlated with regions that are less affected by residual gas, is not observed in the GB mass spectrum
Summary
Atom probe tomography (APT) is a microscopy and microanalysis technique that maps the position of millions of atoms from a material in three-dimensions with subnanometer spatial resolution. The technique relies on the effect of intense electric fields to cause the desorption and ionization of the atoms that constitute the surface of a sharp, needle-shaped specimen. The ions are accelerated away from the specimen’s surface by the electric field and collected by a position-sensitive, time-resolved particle detector. The high curvature of the specimen’s tip (radius of curvature in the range of 20–200 nm) makes the electrostatic field highly divergent, and provides a very high magnification, in the range of 106, to the image formed by the impact of the ions on the detector. The elemental identity of each atom is revealed through time-offlight mass spectrometry [1].
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