Optimization of the Experimental Parameters Affecting the Corrosion Behavior for Mg–Y–Zn–Mn Alloy via Response Surface Methodology

Abstract

This paper optimizes experimental parameters on controlling corrosion performance of the Mg-rare-earth alloys with long period stacking ordered structure using response surface methodology. Different NaCl concentrations, temperatures, and varying pH values are selected as input parameters. The corrosion current density (icorr) and open circuit potential (OCP) are used as the multiple responses to evaluate the corrosion performances. The corrosion surface morphology and corrosion mechanism of the Mg alloys are also investigated by scanning electron microscopy for the optimization. Analysis of variance (ANOVA) has given the impact of individual factors and interactions on the corrosion rate. The results indicated that the three test parameters had significant impacts in controlling the corrosion behavior of Mg alloy. Moreover, the increased NaCl concentration decreased the pitting potential (Epit) of the target materials. Filiform corrosion can be detected in high pH solutions, whereas the matrix suffered from severe dissolution phenomenon in low pH solutions. High temperature aggravated the local destruction and dissolution of the protective film. The interaction of the experimental parameters showed a sizable influence on corrosion performance.