Quantitative fast Fourier transform based arrangement analysis of porous anodic oxide formed by self-organized anodization of FeAl intermetallic alloy

• FeAl intermetallic alloy was anodized in sulfuric acid.
• Porous oxide was obtained.
• Fast Fourier Transform based arrangement analysis was done.
• Since 15 V, two-step anodizing improves arrangement.
• The greater voltage the better final arrangement of the pores.

FeAl intermetallic alloy was anodized in 20 wt% sulfuric acid at 0 °C for 1 min at the voltage ranging from 5 to 20 V with a step of 2.5 V. Based on the FE-SEM images, fast Fourier transformed (2D-FFT) quantitative arrangement analysis of the porous oxide was performed for the oxide formed after the first and the second step of anodization. It was found that for voltages below 15 V FFT-derived regularity ratio values for both steps are comparable. For 15 V and greater voltages regularity ratio of the obtained anodic oxide is much better while a two-step procedure is employed. Conducted research revealed that two-step self-organized anodization improves regularity of the porous oxide formed on FeAl intermetallic alloy. Moreover, regularity ratio increases rapidly with the anodizing voltage for the second step of anodization.