The non-extensive spinodal line: implications for the early stage solid-solid precipitation in alloys

Non-equilibrium thermodynamic processes are characterized by deviations from Boltzmanns distribution for the microstates, which leads to the breakup of extensivity of thermodynamic state variables. Tsalllismethod allows to take account of this effect by introducing a parametric expression for the systems entropy. The authors had shown previously that Tsallisentropy allows to move the spinodal line arbitrarily close to the binodal lines of a phase separating phase diagram in the Bragg-Williams approximation and interpreted experimental findings on the early stage precipitation in metallic alloys. The present work investigates this effect using the Bethe approximation.