319 alloy has been selected for the study in the present work due to its wide use in many applications. 319 alloy is used in automotive and aerospace industry for the complicated castings which must comply high strength requirements. In practice, the most common elements with the modifying effect are strontium, sodium and antimony. The addition of these elements leads to a change in the shape of eutectic silicon, resulting in an increase of the mechanical characteristics and the microstructure. An experimental program has been undertaken to explore the effect of antimony on chosen mechanical properties and the microstructure of investigated alloy. An analysis of the results of these experimental works is made in order to determine an optimum Sb (Al-10% Sb) addition to produce material exhibiting desirable properties. Experimental works have showed that the addition of the Al-10% Sb results in similar or even higher mechanical properties than the conventional 319 alloy. Based on the carried out experiments the best combination of mechanical properties has been achieved by the addition of 2 000 ppm Al-10% Sb.
 A.K. Dahle, K. Nogita, S.D, McDonald, C. Dinnis, L. Lu, Eutectic modification and microstructure development in Al- Si alloys, Materials Science and Engineering A 413-414, 243-248 (2005).
 F.C. Dimayuga, Veredelung von Aluminium-Silicium- Legierungen mit Strontium, Natrium und Antimon, Giesserei Praxis 23/24 (1991).
 C.M. Dinnis, A.K. Dahle, J.A. Taylor, Three - dimensional analysis of eutectic grains in hypoeutectic Al-Si alloys, Materials Science and Engineering A 392, 440-448 (2005).
 J.E. Gruzleski, B.M. Closset, The Treatment of Liquid Aluminum-Silicon Alloys, USA: American Foundrymen’s Society Illinois (1990).
 D. Kube, F.J. Klinkenberg, S. Engler, Einfluß von Antimon und Wismut auf die Veredelung und die Porosität bei der Legierung AlSi9Cu3. Giesserei 9/8 (1998).
 Medlen, D., Bolibruchová, D., 2011. Influence of antimony on the mechanical properties and gas content of alloy AlSi6Cu4. Archives of Foundry Engineering 11,73-78 (2011).
 D. Medlen, D. Bolibruchová, Influence of remelting on the properies of AlSi6Cu4 alloy modified by antimony, Archives of Foundry Engineering 12, 81-86 (2012).
 F.J. Tavitas-Medrano, J.E. Gruzleski, F.H. Samuel, S. Valtierra, Effect of Mg and Sr-modification on the mechanical properties of 319-type aluminum cast alloys subjected to artificial aging. Mater Sci Eng A 480, 356-364 (2008).
 N. Tenekedjiev, B.M. Closset, Microstructures and thermal analysis of strontium treated aluminum-silicon alloys, American Foundrymen’s Society Illinois 1990.
 M. Warmuzek, Aluminium-Silicon Casting Alloys: An atlas of microfractographs. ASM International, Materials Park, USA 2004.