Morphologies and growth mechanisms of α-Al(FeMn)Si in Al-Si-Fe-Mn alloy

In this paper, the morphologies of α-Al(FeMn)Si phase in Al-6Si-4Fe-2Mn alloy were investigated in three-dimensional space by observing the fractograph. Under the experimental condition, two kinds of morphologies were obtained, rhombic dodecahedron and dendrite. The rhombic dodecahedron are covered by twelve {1 1 0} faces due to their lower growth rates. The effects of constitutional supercooling and cooling rate are thought to be reasons for the development of dendrite crystals, which also exhibits typical crystallographic features. Combining with the crystal shapes obtained at different growth stages, the growth mechanisms of both rhombic dodecahedron and dendrite were discussed.