Simulation of Heterogeneous Atom Probe Tip Shapes Evolution during Field Evaporation Using a Level Set Method and Different Evaporation Models

TL;DR

This paper develops a level set simulation method to model the complex shape evolution of heterogeneous atom probe tips during evaporation, highlighting the impact of evaporation laws and interface curvature on reconstruction artifacts.

Contribution

It introduces a novel level set based model for simulating heterogeneous tip shape evolution in atom probe tomography, improving interface representation and accounting for different evaporation laws.

Findings

The level set model qualitatively agrees with finite element and literature data.

Asymmetric shape evolution reveals complex evaporation behavior of heterogeneous tips.

Evaporation laws significantly influence tip shape evolution.

Abstract

In atom probe tomography (APT), accurate reconstruction of the spatial positions of field evaporated ions from measured detector patterns depends upon a correct understanding of the dynamic tip shape evolution and evaporation laws of component atoms. Artifacts in APT reconstructions of heterogeneous materials can be attributed to the assumption of homogeneous evaporation of all the elements in the material in addition to the assumption of a steady state hemispherical dynamic tip shape evolution. A level set method based specimen shape evolution model is developed in this study to simulate the evaporation of synthetic layered-structured APT tips. The simulation results of the shape evolution by the level set model qualitatively agree with the finite element method and the literature data using the finite difference method. The asymmetric evolving shape predicted by the level set model demonstrates the complex evaporation behavior of heterogeneous tip and the interface curvature can potentially lead to the artifacts in the APT reconstruction of such materials. Compared with other APT simulation methods, the new method provides smoother interface representation with the aid of the intrinsic sub-grid accuracy. Two evaporation models (linear and exponential evaporation laws) are implemented in the level set simulations and the effect of evaporation laws on the tip shape evolution is also presented.