Abstract: The paper deals with the influence of molybdenum, zirconia and cobalt on the AlSi10Mg (Cu) alloy microstructure. The work methodology was focused on the analysis of phases morphology for material alloyed with Mo, Zr and Co. Molybdenum in the AlSi10MgCu alloy creates phases with skeletal morphology bounded on iron phases Al(Fe, Mn, Mo)Si. Used heat treatment has softened these phases and is a prerequisite for increasing the strength characteristics and hardness. By alloying the alloy with zirconium to isolate Al3Zr phases, which represent a strong nucleation potential for α-Al. It has been confirmed that Al3Zr particles do not tend to interact with other elements. The results of experiments show that cobalt affects the morphology of iron phases. The findings of this study can provide further insight into the transition metals in Al-Si-Mg-Cu alloys and the potential for developing a new generation of heat-resistant alloys based on Al-Si.