Nominal vs. active supersaturation of solutions during homogeneous nucleation: An application to Al-Zr and Al-Sc alloys.
Following the formalism of the Classical Nucleation Theory beyond the ideal solution approximation, this paper considers a difference between the active solute supersaturation (given by the solute thermodynamic activity ratio) and the nominal supersaturation (given by the solute concentration ratio) due to formation of subcritical transient solute clusters, called heterophase fluctuations. Based on their distribution function, we introduce a simple universal equation that couples the nominal supersaturation of a metastable solution with its active supersaturation and a function of the interface energy and temperature. The applicability of this approach is illustrated by fitting of some simulation data on nucleation in supersaturated Al-Zr and Al-Sc solid solutions.
Publisher URL: http://arxiv.org/abs/1707.08777