Optimizing the Corrosion Parameters and Assessing Corrosion Inhibitions for Cast Cu45Mn25Al15Fe5Cr5Ni5 HEA in Nitric Acid Solution via DOE and RSM Analysis

The corrosion performance of the cast Cu₄₅Mn₂₅Al₁₅Fe₅Cr₅Ni₅ HEA was examined in HNO₃ solutions of varying concentrations (0.5%, 1%, 5%, and 10%). The microstructure and elemental composition of the alloy were examined using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Corrosion behavior was assessed through the weight-loss method at room temperature. To gain a thorough understanding of the corrosion parameters, both statistical analysis and interaction plots were utilized. Central composite design (CCD) was applied to investigate the primary and interaction effects of these parameters on the response. The optimal parameters for maximizing output were determined. Response Surface Methodology (RSM) with conditions of 24 h, 5% HNO3 concentration, and a pH of 0.248 predicted a maximum fit of 81.64%. RSM also allows for more detailed analyses of the individual and interaction effects between the variables. The corrosion rate (CR) increased with higher HNO₃ concentrations. When 0.5% HNO₃ was used, the inhibitor additions of Nano-TiO₂, Nan-SiO₂, or Nano-ZnO resulted in decreased CR values from 1.04 mm/y to 0.11, 0.12, or 0.22 mm/y, respectively.