Nonergodic correction to a binary mixture phase diagram

• Nonergodic correction results in a bifurcation of phase separation line.
• Two critical and one triple points appear due to this bifurcation.
• Microheterogeneous state may exist as a separate nonergodic phase.
• This situation is typical for the eutectic binary systems.

For a binary mixture with limited miscibility of the components, the correction to the equation of state that arises from the finite diffusion velocity is discussed. It is shown that this correction corresponds to a nonergodic microheterogeneity of the mixture. We suggest that the above microheterogeneity may be accounted as corresponding fluctuations of the chemical potential. The mean square of these fluctuations CC is an additional thermodynamic variable, and the nonergodic microheterogeneity is an equilibrium property of every binary mixture with limited miscibility. The experimental status of this statement is discussed for eutectic and monotectic systems.