Local supersaturation during melting in a temperature gradient

A homogeneous single-phase Al–Cu alloy was exposed to a steep temperature gradient for a short time interval, melting of the sample at the hot end was interrupted at intermediate stages. In the resolidified microstructure, the local supersaturation was determined by analysing concentration profiles across former liquid films at grain boundaries and adjacent zones in the grain interior. Already at moderate heating rates (3 K/s) significant supersaturations occurred and were quantified.