Simultaneous improvement in corrosion resistance and hardness of a model 2xxx series Al-Cu alloy with the microstructural variation caused by Sc and Zr additions

The microstructural variation caused by Sc and Zr additions to a 2xxx series Al-Cu alloy was studied in the context of corrosion and hardness. The addition of Sc and Zr led to microstructural refinement, a decrease in corrosion current density, and a reduction in the extent of pitting and intergranular corrosion; whilst hardness increased. Such an improvement in properties was attributed to the variation of alloy microstructure. It was also noted that an often unreported W-phase (Al_xCu_5-6ScZr_y≈0.3), containing Zr, was ‘cathodic’ relative to the Al-matrix in the Al-Cu-Sc-Zr alloy.