Polymorphism of iron in binary systems

A method is developed to determine the boundaries of equilibrium α-and γ-phase fields in iron-based binary systems with closed and open γ fields. The equilibrium lines are plotted using the deviations of the difference in the free energies of the iron polymorphic modifications from the corresponding values for pure iron. An expression is obtained to quantitatively describe the boundaries of the α-γ and γ-δ transformations depending on the alloy composition and temperature.