Liquid AI -Si alloys are usually given special treatments before they are cast to obtain finer or modified matrix and eutectic structures, leading to improved proper ties. For many years, sodium additions to hypoeutectic and eutectic AI -Si melts have been recognized as the most effective method of modifying the eutectic morphology, although most of the group IA or IIA elements have significant effects on the eutectic s tructure. Unfortunately, many of these approaches also have associated several founding difficulties, such as fading, forming dross in presence of certain alloying elements, reduced fluidity, etc. ln recent years, antimony additions to AI -Si castings have attracted considerable attention as an alternative method of refining the eutectic structure. Such additions eliminate many of the difficulties listed above and provide permanent (i.e. non -fading) refining ability. In this paper, the authors summarize work on antimony treatment of Al -Si based alloys.

The paper deals with the impact of technological parameters on the mechanical properties and microstructure in AlSi12 alloy

using squeeze casting technology. The casting with crystallization under pressure was used, specifically direct squeeze

casting method. The goal was to affect crystallization by pressure with a value 100 and 150 MPa. From the experiments we

can conclude that operating pressure of 100 MPa is sufficient to influence the structural characteristics of the alloy AlSi12.

The change in cooling rate influences the morphology of the silicon particles and intermetallic phases. A change of excluded

needles to a rod-shaped geometries with significantly shorter length occurs when used gravity casting method. At a pressure

of 100 MPa was increased of tensile strength on average of 20%. At a pressure of 150 MPa was increased of tensile strength

on average of 30%. During the experiment it was also observed, that increasing difference between the casting temperature

and the mold temperature leads to increase of mechanical properties.