Calculating the Fractal Dimension of Surface Topography Obtained by Scanning Electron Microscopy and Atomic Force Microscopy

Alternative methodologies to analyze and quantify surface morphology using techniques such as Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) are of great interest to researchers. This study presents an approach using fractal dimension (D) analysis to characterize FeCrAl alloy plates oxidized in an air atmosphere at 750, 800, 850, and 900 °C for 24 h. SEM and AFM surface traces were used to determine the fractal dimensions via Rescaled Range (R\S) analysis using the BENOIT program; with this, it is expected that the fractal dimension results are between 1 ≤ D ≤ 2. The fractal dimension analysis describes with precision the surface morphology, given that local topographic features are represented by the analyzed traces. The experimental results demonstrate that D increases with the oxidation temperature for both techniques, which correlated with an increase in surface roughness. Specifically, SEM results in D values of 1.402, 1.545, 1.557 and 1.583, while AFM results in values of 1.494, 1.561, 1.573 and 1.593 at respective temperatures. Fractal dimension analysis is a robust tool for quantifying micro- and nanostructured roughness. This approach allows researchers to track surface changes induced by thermal, mechanical, or environmental processes, thus transforming SEM into a quantitative complementary technique.