The paper deals with the impact of technological parameters on the heat transfer coefficient 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. The pressure applied to the melt causes a significant increase of

the coefficient of heat transfer between the melt and the mold. There is an increase in heat flow by approximately 50% and the heat

transfer coefficient of up to 100-fold, depending on the casting conditions. The change in cooling rate influences the morphology of the

silicon particles and intermetallic phases. A change of excluded needles to a rod-shaped geometry with significantly shorter length occurs

when used gravity casting method. By using the pressure of 150 MPa during the crystallization process, in the structure can be observed an

irregular silica particles, but the size does not exceed 25 microns.