Modification of molten metal is performed for the eutectic and subeutectic silumins prior to its casting by using strontium, which has a time-limited effect up to 1-1.5 hours. Beryllium is used in order to prolong the modifying effect. The aim of the experiment is to examine both the distribution and the effect of beryllium in the structure on the temporary extension of the modification in the Al-Si alloys in combination with strontium modifier. Beryllium is used as a master AlBe 5 alloy, and samples are cast by gravity casting in a preheated metal moulding. Chemical analysis is performed by means of spectral analysis. Specimens are evaluated by using a confocal microscope. The elements' distribution in the AlSi 7 Mg 0.3 alloy microstructure, with emphasis on the distribution of Sr and Be as the individual structural components, is investigated using a scanning electron microscope with EDS analyser.