Phase selection and re-melting-induced anomalous eutectics in undercooled Ni–38 wt% Si alloys

On the origin of anomalous eutectic growth from undercooled melts: Why re-melting is not a plausible explanation

“…Such a structure would strongly resemble the anomalous eutectic observed here and does, we believe, offer a plausible origin of the anomalous eutectic without invoking extensive remelting of the primary solid (Ag-Cu eutectic cells/dendrites). As such, the model proposed here aligns with that of [3,7,11,14,21] who have previously suggested a role for uncoupled growth in the formation of the anomalous eutectic, although the mechanism giving rise to this uncoupled growth is different.…”

“…However, as pointed out by [20], there are few systems in which eutectic growth is reported at undercoolings  200 K, these being limited to systems in which at least one phase is an intermetallic compound. Recently Lai et al [21] have demonstrated that in the Ni-Si system anomalous eutectic formation is accompanied by a double recalescence event, a phenomenon also observed in Ag-Cu [5].…”

Metastable solidification pathways of undercooled eutectic CoSi–CoSi2 alloys

“…Rapid solidification of undercooled eutectic alloys has attracted considerable interest in past decades due to their unique competitive nucleation and growth mechanisms. In particular, many studies have been carried to understand non-equilibrium phenomena such as metastable solidification behavior and a morphological transition from regular lamellar eutectic to anomalous eutectic in a number of eutectic systems such as Ni-Sn [1][2][3], Ni-Si [4,5] Co-Sn [6,7], Ag-Cu [8,9], and Co-Si [10][11][12][13][14]. Solidification microstructures of those alloys have been shown to depend on experimental conditions.…”