Corrosion behavior of Al–3Mg–0.2Sc alloy processed by high-pressure torsion and thermal treated

Abstract

This work aims at evaluating the effect of microstructure on the corrosion behavior of an Al–Mg–Sc alloy processed by high-pressure torsion (HPT) and annealed from 523 to 773 K. The corrosion resistance of the annealed alloy was evaluated by using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests in 3.5% (wt.%) NaCl solution. The EIS and polarization analyses suggested a higher corrosion resistance of the Al–Mg–Sc alloy that presented a more homogeneous grain distribution. The Al alloy samples were characterized by scanning electron microscopy (SEM) after the polarization tests. The heterogeneity of the microstructure, but also the formation of a high density of grain boundaries during HPT processing, and a change in the structure of grain boundaries, including the formation of grain boundary segregations of alloying elements, affected the corrosion behavior of the HPT processed and thermal annealed Al–Mg–Sc alloy.

Keywords

• Aluminum alloy
• Corrosion
• High-pressure torsion
• Ultrafine microstructure
• Grain distribution