Abstract:Solidification process ofα(Al)-Mg₂Ge pseudobinary eutectic alloys in Al-Mg-Ge system has been studied by directional solidification and electron microscopy techniques. It was demonstrated that the morphology of the primary crystal of phase Mg₂Ge is octahedron enclosed with {111} planes and Mg₂Ge is the favored nucleating phase during eutectic solidification of this alloy. The branching process during solidification fits the mechanism of branching in the preferred growth direction. First, the primary branching occurs in the [110] direction of the primary crystal of Mg₂Ge, and then the second branching appears in the [110] direction of the primary branch. It progresses in this way till stable growth.

Key words: eutectic solidification　mechanism　branching　preferred growth direction　nucleation