On two-phase coherent equilibrium in binary alloys

The effect of coherency stresses on two-phase equilibria is treated adopting Williams' approach that the Gibbs energy of the coherent state is obtained by simple adding the elastic energy to the Gibbs energy of the unstressed state. Under those circumstances the general equilibria conditions are reasonably simple and may be applied in practical calculationss for alloys where the thermodynamic data are available. The stability of the coheren state is discussed in terms of Gibbs energy diagrams. Some general features and the inapplicability of the phase rule are furthers discussed. In addition the coherent α-γ equilibrium in the binary FeMn system is calculated assuming simple geometrys and applying assessed thermodynamic functions.