(Fig. 2a), polygonal-shape π-AlSiMgFe (Fig. 3a) and light grey β-AlFeSi (Fig. 4a). Figs. 2–4b, show the EDX spectrums corresponding with the analysed phases. These intermetallic phases where identified by comparing their characteristics with those of phases found in microstructural observations carried out previously by others authors [12–15]. The Mg2Si dissolution in the aluminium α matrix is the main reason for the age hardening, due to the formation of a fine dispersion of coherent precipitates, in accordance with the book published by Polmear [16].