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 20 wt%, sulfuric acid at 0 degrees 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 anodizatidn. (C) 2015 Elsevier B.V. All rights reserved.