Characterisation and Validation of Submicron Structures in a Fe–Al–Nb Alloy Using Inverse Modelling of the P_N Method for EPMA

¹ Central Facility for Electron Microscopy, RWTH Aachen University, Aachen, Germany
² Applied and Computational Mathematics, RWTH Aachen University, Aachen, Germany

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Published online: 29 January 2026

Abstract

Using conventional matrix correction methods, the spatial resolution of EPMA is limited by the size of the electron interaction volume. Secondary and back-scattered electron imaging techniques achieve higher spatial resolution, but can only provide structural information at the surface of the sample. In this study, we present a method for reconstructing complex three-dimensional material structures in EPMA by means of inverse modelling, based on the deterministic spherical harmonic P_N method for simulating electron transport in solids. We apply this approach to characterise submicron structures in an Fe-Al-Nb alloy, where the structural features are smaller than the interaction volume. The accuracy of the reconstructed material structure is further validated by comparing with cross-sectional micro-structural information obtained via FIB/SEM tomography.