Effect of experimental aging on the performance of Al-7.9Mg-13.3Zn and Al-10.5Mg-8.6Zn alloys as sacrificial anodes

Abstract 
Light aluminum alloys have a great importance in industry owing to generally accessible costs, low density, good machinability, and corrosion resistance under certain environments. The present work studies aging treatments that preform important roles on the distribution and microstructural changes of two AlMg-Zn alloys, and the resulting effect on the corrosion behavior. The experimental AlMg-Zn alloys were cast and then heat treated at 200 °C, after the solubilization treatments were made, using different treatment times. These alloys showed important changes in their corrosion mechanisms, but mainly, corrosion started at AlxMgyZnz complex phases in both alloys. The optimal corrosion rates were reached after 5 and 24 h of heat treatment. These results were obtained through electrochemical techniques in NaCl solutions, and by metallographic analysis using SEM and optical microscopy.