Influence of microalloying additions on Al-Mg alloy. Part 1: Corrosion and electrochemical response

A range of custom alloys based on the Al-4Mg-0.4Mn system were produced with selected quaternary microalloying additions. Alloying elements studied include silicon, zinc, lead, titanium, tin, zirconium, strontium and neodymium. To characterise the corrosion response, electrochemical tests were carried out in 0.1M NaCl, supplemented by constant immersion tests and basic microstructural characterisation by means of scanning electron microscopy (SEM). Optical profilometery was used to determine the form and intensity of localised corrosion. The results indicate that low level quaternary alloying additions can have a marked influence on specific aspects of the first order correlation between chemistry, microstructure, hardness and corrosion.