with those measured for the T6 condition, the principal effect of this treatment being, in fact, the increasing of the ductility of the material with an increase in mechanical properties respect to the as-thixo alloy. From this point of view the best conditions appear (T6 ones) to be 160◦C 4 h and200◦C 4 h. An extensive evaluation of longitudinal sections of tensile tested samples was finally carried out by scanning electron microscopy. In all the observed conditions the fracture propagates in the eutectic region around the globules (Fig. 9). The fracture surfaces of the as thixo and T5 specimens revealed a brittle behaviour as clearly shown in Fig. 10. On the contrary,the specimens in the T6 condition revealed a ductile behaviour demonstrated by the presence of dimples around the bigger particles visible in the microstructure (Fig. 11). The described behaviour was evidenced in all the fracture surfaces and was due to the solution treatment prior of the ageing one of the material (Fig. 12).