Primary dendrite spacing in land-fast polar sea ice

摘要

When an impure melt is subjected to unidirectional solidification, microsegregation occurs at the solid-liquid interface and the solidification front develops a cellular, dendritic or lamellar structure [1-5]. These solidification features are observed in both natural and engineering materials, and are known to affect their mechanical properties. Sea ice is a prime example of a natural material that exhibits impurity entrapment [6,7] and grain-scale substructure very similar to binary alloys [8-15]. Salt entrapment and dendritic microstructure in sea ice has been explained by modelling the natural solidification of sea-water as that of a dilute solution of l-bO-NaCl solution [16, 17] because NaCl is the major impurity species.