Theoretical description of slow non-monotonic relaxation processes in Al–Y melts

The slow non-monotonic relaxation processes, which have been recently fixed in Al–Y melts, are described theoretically. The theoretical description is based on the Cahn–Hilliard theory and functional methods of non-equilibrium dynamics. In terms of the suggested approach the reasons of this relaxation kinetics are non-linearity of the system near to the liquidus line, which sharply increases with Y concentration, and strong initial heterogeneity of the melt on the concentration of Y atoms. According to our analysis one can conclude that the non-monotonic temporal dependence of viscosity is caused by the Ostwald ripening processes in the rich in yttrium areas. •We develop the theoretical explanation of slow non-monotonic relaxation processes in Al–Y melts.•We believe the reason of this relaxation kinetics is non-linearity of the system near liquidus line.•We obtain the analytical expressions for the temporal dependence of the Al–Y melts viscosity.•We conclude that the slow non-monotonic relaxation is caused by the Ostwald ripening processes.