Solubility diagram of the Cu-Ni nanosystem

The application of equilibrium thermodynamics to a nanosystem changes Gibbs's rule of geometrical thermodynamics. This fact leads to the necessity to reconsider the phase diagram and solubility curve concepts. The notions of 'solubility diagram', 'solidus', 'liquidus' are used to discuss the case of phase transition in Cu-Ni nanoparticles. It is shown that, in the limit where thermodynamic arguments remain valid, the solubility diagrams of nanoparticles are functions of their size and nucleation mode. This is demonstrated for different sizes.