The thixocasting technology is now widely used in the production of components designed for the automotive industry. One of the major reasons is that it permits the design of products characterized by lower weights and very complex geometries in a single step cycle with respect to traditional techniques and materials. By using thixoforming it is also possible to improve the tool life, the mechanical properties of the components and realize net shape products [1]. The alloys from the Al-Si system are the most widely used in the foundry industry thanks to their good castability and highstrengthtoweightratio;themicrostructureofsuch materialsconsistsofaprimaryphase,aluminumorsilicon and an eutectic mixture of these two elements. These materials contain many impurities: such alloying elements partly go into solid solution in the matrix and partly form intermetallic particles during the solidification process [2]. Among cast aluminium alloys, A356 ranks as one of the commercially important alloys used in automotive applications, on account of its excellent casting characteristics and good mechanical properties. For these reasons, the A356 is one of the candidate alloys to perform the shaping of aluminium alloysinthesemisolidstateorthixocastingthathasbecome a widely accepted industrial process in the last years [3]. Thixotropic aluminium alloy used at a liquid fraction of around 50% presents, with respect to its 100%liquidhomologueusedinconventionalhighpressure die casting, three major difference [4]: (i) a much higher viscosity, that permits to inject the material at relatively high speeds; (ii) a lower heat content allowing a considerable increase in production rate; and