Existence of seaweed structures in rapidly solidified Ni3Ge intermetallic

The congruently melting, single phase intermetallic β-Ni3Ge has been subject to rapid solidification via drop-tube processing. A range of morphologies are observed in this material including spherulites, dendrites (which may display either orthogonal or non-orthogonal side-branching), a recrystallized structure and dendritic seaweed with increasing departure from equilibrium. In the case of the seaweed structure only, a progressive transition from high undercooling morphologies near the nucleation point to low undercooling morphologies is evident as growth proceeds. This appears to indicate that unlike normal dendritic growth, seaweed growth does not reach a steady-state and may in fact be more akin to growth at a planar interface.