Influence of micro-alloying with silver on microstructure and mechanical properties of Al-Cu alloy

The present study aims to investigate the microstructure and mechanical properties of Al-Cu-Zn-Fe-Ti-Mg alloy (≈ 2219 Al-alloy), micro-alloyed with silver (Ag in the range 0 − 0.1 wt%), under different thermo-mechanical process conditions. Investigation of the microstructure of cast alloys revealed the presence of intermetallic CuAl2 and metastable Al-Cu-Fe-Zn-Si-Mn phases at the grain boundary regions. The as-cast dendritic structure was eliminated by heat treatment and subsequent rolling process resulting in improved mechanical properties. The strength and hardness increased with the increase in silver content up to 0.07 wt% in combination with reasonable ductility. Maximum strength for the alloy was achieved in the rolled and age hardened condition. Fractographic studies revealed brittle failure in as-cast alloys, whereas the heat treated alloys exhibited features typical of ductile failure.