Thermal analysis of Al-Cu-Mg-Si alloy with Ag/Zr additions

Heat-treatable aluminium alloys are widely used for structural applications. Their strength is obtained through age hardening phenomena, that are sensitive to microalloying. In the present paper the results of thermal analyses on the ageing behaviour of an Al–Cu–Mg–Si alloy with silver and zirconium additions are presented. Specimens were water quenched after solution heat treatment, then aged at 453 K and a hardness-versus-time plot was drawn. Samples representative of different ageing conditions were subjected to DSC scans. Peaks were identified taking into account and Q phases precipitation sequences. Solution treated samples showed GP///Q sequence, while in peak aged condition GP and precipitation peaks disappeared and a reduction of peak area was observed, witnessing the concurrent presence of and phases at peak hardness condition. Experimental data were compared with results from analogous investigations performed on a conventional commercial Al–Cu–Mg–Si alloy.