Ternary Diagrams S.J.T.U. Phase Transformation and Applications Page 15/34 In an isothermal section Three-phase field may exist:no degrees of freedom,and the composition of those phases will be fixed F=C-P+1 F-C-P Overall XA=FaxAa+Faxap+FxA.r composition,O xB=FaxBa+FnxB+FxB.y Xc=Faxca +Fpxc.B+Fxc.r Figure 9.21 Three-phase equilibrium. SJTU Thermodynamics of Materials Spring2008©X.J.Jin Lecture 18 Phase Diagram IVPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2008 © X. J. Jin Lecture 18 Phase Diagram IV Page 15/34 Ternary Diagrams In an isothermal section Three-phase field may exist: no degrees of freedom, and the composition of those phases will be fixed = − PCF +1 A A, A, A,γγββαα = + + xFxFxFx B B, B, B,γγββαα = + + xFxFxFx C C, C, C,γγββαα = + + xFxFxFx −= PCF