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γ-Al₂O₃ particles form inevitably in liquid Al- alloys during liquid-handling and casting processes. Such oxide particles may act as potential nucleation sites during solidification. Recent research revealed that native γ-Al₂O₃ particles exhibit different potency for nucleating solid Al, which may reduce the number of potential nucleation sites in the liquid. Chemical segregation at the liquid/oxide interface may modify the substrates’ nucleation potency. In this paper, we investigated prenucleation at the Al(<i>l</i>)/γ-Al₂O₃ interface with segregation of Sc, Y and La (Group 3) atoms using an ab initio molecular dynamics simulation technique. Our results revealed that the segregation of Sc, Y and La results in a reconstruction of the Al atoms adjacent to the substrates and consequently a rough substrate surface. Present investigation opens a new path for manipulating solidification processes via chemical segregation at the liquid/substrate interface.