<p>In Al–Si–Cu–Fe alloys, localized cerium conversion coating (CeCC) deposition on intermetallic (IM) particles is strongly influenced by surface preparation. Here, we investigate how single-step etching (NaOH only) and multi-step etching and pickling (NaOH + HNO₃​) preparation times affect CeCC nucleation and growth on Cu-rich θ-Al₂Cu and Fe-rich β-Al₅FeSi IMs in directionally solidified Al-7Si-2Cu-1Fe and Al-7Si-1Fe alloys. The reactivity of surface was characterized with AFM–SKPFM and surface coverage of CeCC deposits characterized with SEM. A quantitative analysis was performed to discern the effects of different surface preparation procedures on CeCC deposition. Single-step NaOH activates both IMs but leaves substantial Al(OH)₃​ smut on θ-containing alloys, which elevates local pH yet introduces variability in coating coverage. In contrast, multi-step etching removes smut, ensuring more consistent CeCC on θ-Al₂Cu driven primarily by cathodic activity of the IMs. Fe-rich β-Al₅FeSi IMs exhibit nearly 100% coverage even after a short 30&#xa0;s NaOH etch and 0.5&#xa0;h CeCC treatment, whereas Cu-rich θ-Al₂Cu requires 120&#xa0;s NaOH etching plus HNO₃​ pickling for reliable coverage. Prolonged CeCC times promote lateral deposit growth on both IM types when using single-step NaOH, but such growth is absent for θ-Al₂Cu in multi-step samples. These findings reveal that Al(OH)₃​ smut, coupled with local Volta potential and alkaline microenvironments, governs IM reactivity during conversion coating formation. Accordingly, single-step NaOH is sufficient for Fe-rich alloys, while multi-step etching is recommended for Cu-rich alloys. This work provides insights into optimizing surface preparation for improved and predictable CeCC deposition on distinct intermetallic phases.</p>