Reflections on the Analysis of Interfaces and Grain Boundaries by Atom Probe Tomography

Abstract

Interfaces play critical roles in materials and are usually both structurally and compositionally complex microstructural features. The precise characterization of their nature in three-dimensions at the atomic scale is one of the grand challenges for microscopy and microanalysis, as this information is crucial to establish structure–property relationships. Atom probe tomography is well suited to analyzing the chemistry of interfaces at the nanoscale. However, optimizing such microanalysis of interfaces requires great care in the implementation across all aspects of the technique from specimen preparation to data analysis and ultimately the interpretation of this information. This article provides critical perspectives on key aspects pertaining to spatial resolution limits and the issues with the compositional analysis that can limit the quantification of interface measurements. Here, we use the example of grain boundaries in steels; however, the results are applicable for the characterization of grain boundaries and transformation interfaces in a very wide range of industrially relevant engineering materials.

Evolution of substructure in low-interstitial martensitic stainless steel during tempering

“…The width of the segregation profile is notably larger than the one of an actual interface. The degradation of the actual interfacial width is instrument-related and known as the local magnification effect [37]. The effect increases with the inclination of the interface, which is high (>60°) in the present case.…”

Revealing in-plane grain boundary composition features through machine learning from atom probe tomography data

“…The specific axis chosen here coincides with the field evaporation axis that was used in the APT experiment. Choosing this axis has the advantage of minimized APT reconstruction aberration effects [60,84]. Thus, at a certain rotation angle, 𝜃, a GB edge-on configuration is achieved and a clear edge-on GB decoration projection is now present with minimal aberrations in the reconstruction.…”

“…Thus, the 3D reconstruction from APT offers one additional dimension of information to TEM-based techniques, when exploring chemical features in GBs. Typical visualization tools for APT include chemical iso-composition or iso-density surfaces, which help to highlight the location of features with a specific composition or density value [58][59][60]. One-dimensional (1D) line profiles and 2D contour maps can aid to quantitatively displaying of the local composition [61].…”

Atom probe analysis of electrode materials for Li-ion batteries: challenges and ways forward

“…Atom probe tomography (APT) 15 has been proposed as a technique to reveal the three-dimensional distribution of Li in these materials. APT provides compositional mapping with subnanometre resolution 16,17 , and its sensitivity is in principle not related to the atomic weight, hence Li can be readily detected and its distribution analysed. However, there are specific challenges inherent to the analysis of alkali by APT [18][19][20] .…”

“…Atom probe tomography (APT) 15 has been proposed as a technique to reveal the three-dimensional distribution of Li in these materials. APT provides compositional mapping in threedimensions with sub-nanometre resolution, 16,17 and its a Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany. E-mail: b.gault@mpie.…”