Abstract: There exist Marked differences between effects of modification with some elements or. eutectic Al-Si alloys. In this paper, (111)si of single crystal silicon seeds immersed into melts of Al-22wt% Si alloy treated with Na, Sr, rare-earths and Sb were analyzed by XPS and AES in order to detect the adsorbability of these elememts. Results show that Na and Sr Can be adsorbed on (111)si but rare-earths and Sb can not be. Modifying agents are then divided into two types: adsorbable and non-adsorbable, and different modification mechanisms of the two types are suggested.

Key words: aluminum alloy, eutectic, modification, silicon, surface analysis